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  • 1. Aziman, Cinar
    et al.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    A comparative study on image quality of two digital intraoral sensors.2019In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 48, no 7, p. 1-5, article id 20190063Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The aims of this study were to evaluate the subjective image quality and reliability of two digital sensors. In addition, the image quality of the two sensors evaluated by specialists and general dentists were compared. METHODS: 30 intraoral bitewings from five patients were included in the study, 15 were exposed with a Dixi sensor (CCD-based) and 15 with a ProSensor (CMOS-based) using modified parallel technique. Three radiologists and three general dentists evaluated the images in pair. A five-point scale was used to register the image quality. Visual grading characteristics (VGC) analysis was performed to compare the image quality and the observer agreement was assessed in terms of intra class correlation co-efficient. RESULTS: No statistically significant difference was found on image quality between the sensors. The average scores of the observer agreement were moderate with an average of 0.66 and an interval of 0.30 to 0.87, suggesting that there was a large variation on preference of image quality. However, there was a statistically significant difference in terms of the area under the VGC- curves between the specialist group and the general dentist group ( p = 0.043), in which the specialist group tended to favor the ProSensor. CONCLUSIONS: Subjective image quality of the two intraoral sensors were comparable when evaluated by both general and oral radiologists. However, the radiologists seemed to prefer the ProSensor to the Dixi as compared to general dentists. Inter- observer conformance showed a large variation on the preference of the image quality.

  • 2. Borg, Anna
    et al.
    Klintström, Eva
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Evaluation of low-dose multislice computed tomography, on image quality, in a group of orthognathic patients2018Conference paper (Other academic)
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  • 3.
    Brogårdh-Roth, Susanne
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Månsson, Johanna
    Ridell, Karin
    Malmö högskola, Faculty of Odontology (OD).
    Alward, Lubna
    Malmö högskola, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Ekberg, EwaCarin
    Malmö högskola, Faculty of Odontology (OD).
    Five years' follow-up of dental fear and anxiety, experience of dental care and oral health behaviour in Swedish preterm and full-term adolescents2017In: BMC Oral Health, ISSN 1472-6831, E-ISSN 1472-6831, Vol. 17, article id 145Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: There is rising concern about how preterm birth affects long-term health later in life. The various effects that preterm birth have on developmental outcomes, cognitive profiles and medical health may also affect levels of cooperation in the dental care situation in addition to general oral health and other oral health-related habits. Oral health is an integral part of one's general health and well-being; however, less is known about how prematurity affects oral health and other related areas such as dental care, and including dental fear and anxiety (DFA) in individuals during adolescence and adulthood. This is considered of special interest to study, as preterm children during the preschool and school period were reported to have behavioural problems during dental treatments and less than favourable oral hygiene. METHODS: A questionnaire was used of self-report design and structured into behavioural aspects relating to dental treatment, oral health-related factors, and medical health. This questionnaire at 17-19 years of age was a follow-up from 12 to 14 years of age and considered a predictor for planning future dental care for this group of patients. The 145 participating adolescents were all preterm, born between 23 and 32 weeks of gestation and 140 full-term controls, born ≥37 weeks of gestation. RESULTS: Dental fear and anxiety, oral health behaviour, and intake of sweets and sugary drinks of 17-19-year old adolescents born preterm was comparable to that of the full-term control group. Medical health problems as well as the intake of sweets and sugary drinks increased from the time of early adolescence to late adolescence in both groups. CONCLUSIONS: Preterm as well as full-term adolescents between 17 and 19 years of age are satisfied with their dental care and display low prevalence of dental fear and anxiety (DFA). The findings in this study indicate that adolescents born very preterm and extremely preterm are well prepared for transition to dental care in adult life with expectations of being able to take responsibility for their oral health. KEYWORDS: Adolescent; Born preterm; Dental care; Oral health behaviour

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  • 4.
    Cederhag, Josefine
    et al.
    Malmö University, Faculty of Odontology (OD).
    Iskanderani, Durer
    Malmö University, Faculty of Odontology (OD). Department of Oral & Maxillofacial Radiology, KingAbdulaziz University, Jeddah, Saudi Arabia;.
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD). Specialized Pain Rehabilitation, Skåne University Hospital, Lund, Sweden.
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). Section of Oral and Maxillofacial Radiology, Department ofClinical Dentistry, University of Bergen, Bergen, Norway.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Visibility of anatomical landmarks in the region of the mandibular third molar, a comparison between a low-dose and default protocol of CBCT2023In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 81, no 6, p. 449-455Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Optimization of radiographic examinations is essential for radiation protection. The objective of the study was to investigate the clinical applicability of a low-dose CBCT protocol as compared to the default for pre-surgical evaluation of mandibular third molars.

    MATERIAL & METHODS: Forty-eight patients (62 teeth) referred for pre-surgical mandibular third molar investigation were recruited after justification for CBCT. Two CBCT scans of each site were made using a default protocol and a low-dose protocol (Veraviewepocs 3D F40, J Morita Corp, Kyoto, Japan). The low-dose protocol had the same tube potential (90 kV) and exposure time (9.4 s) as the default, but with reduced tube current, from 5 mA to 2 mA. Four observers evaluated the visibility of five relevant anatomical variables. Image quality was ranked on a 3-point scale as diagnostically acceptable, doubtful, or unacceptable. The Wilcoxon signed-rank test compared differences between the two protocols. The significance level was set at p ≤ .05.

    RESULTS: No significant differences were found between the two protocols for any observer regarding the visibility of the relationship and proximity between the roots and the mandibular canal; root morphology; and possible root resorption of the second molar. The periodontal ligament differed significantly in visibility between the two protocols (p ≤ .05).

    CONCLUSIONS: This study indicates that a low-dose CBCT protocol with a 60% reduction of the tube current provides, in most cases, acceptable image quality for pre-surgical assessment of mandibular third molars. Optimization of CBCT protocols should be a priority according to recommended guidelines.

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  • 5.
    Cederhag, Josefine
    et al.
    Malmö University, Faculty of Odontology (OD).
    Kadesjö, Nils
    Medical Radiation Physics, Karolinska University Hospital, Stockholm, Sweden.
    Nilsson, Mats
    Department of Medical Radiation Physics, Lund University, Malmö, Sweden.
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD). Specialized Pain Rehabilitation, Skåne University Hospital, Lund, Sweden; Scandinavian Center for orofacial Neurosciences, Malmö University, Malmö, Sweden.
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). Section of Oral and Maxillofacial Radiology, Department of Clinical Dentistry, University of Bergen, Bergen, Norway.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Comparison of absorbed doses and organ doses measured with thermoluminescent dosimeters and Gafchromic film for cone beam computed tomography examination of the posterior mandibular region in a head phantom2023In: Oral surgery, oral medicine, oral pathology and oral radiology, ISSN 2212-4403, E-ISSN 2212-4411, Vol. 136, no 6, p. 769-776Article in journal (Refereed)
    Abstract [en]

    Objectives: We aimed to map the correlation between thermoluminescent dosimeters (TLDs) and Gafchromic film for measuring absorbed doses and to compare minimum, maximum, and mean absorbed doses over larger regions of interest and at various craniofacial organs and tissues during cone beam computed tomography (CBCT) exposure of the mandibular third molar region.

    Study design: We positioned TLDs at 75 measurement points in a head phantom. Gafchromic film was cut to the same shape as the 5 levels of the phantom and was placed on top of the TLDs. Both dosimetry methods thus included the surface of each level simultaneously. CBCT scans were made using a 5 × 5 cm field of view and a rotation angle of 200°. Measurements included absorbed dose distributions, doses at all 75 points, and minimum, maximum, and mean doses within organs and tissues.

    Results: The correlation of point-dose measurements at all TLD sites with doses measured on film was strong (R2 = 0.9687), with greatest correlation at lower doses (<2 mGy). Large deviations between TLD and film measurements of minimum and maximum doses and absorbed doses to the organs occurred at all 5 levels. TLD positioning failed to cover several organ sites; for these, only absorbed dose measurements from the film were available.

    Conclusions: TLDs were unable to sample dose distributions and gradients accurately. The characteristics of Gafchromic LD-V1 film make it a favorable alternative in dental CBCT dosimetry.

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  • 6.
    Cederhag, Josefine
    et al.
    Malmö University, Faculty of Odontology (OD).
    Lundegren, Nina
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Evaluation of Panoramic Radiographs in Relation to the Mandibular Third Molar and to Incidental Findings in an Adult Population2021In: European journal of dentistry, ISSN 1305-7456, Vol. 15, no 2, p. 266-272Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES:  The aim was to evaluate the characteristics of the mandibular third molars, especially in relation to the inferior alveolar nerve. Further aims were to investigate incidental findings in panoramic radiographs in an adult population, and to investigate image quality related to patient positioning.

    MATERIALS AND METHODS:  From a previous study with 451 randomly selected adult participants who lived in Sweden, 442 panoramic radiographs from four dental public health clinics were used. The third molars' characteristics and relation to inferior alveolar nerve were evaluated. Incidental findings and patient positioning were recorded.

    STATISTICAL ANALYSIS:  Frequency analysis was used to investigate the occurrence of all findings and their possible interconnections. Whether the patients' age or gender had an impact or not was also analyzed.

    RESULTS:  The third molars were erupted in vertical position among 73% regardless of age. When retained or semi-retained, they were most commonly in mesioangular positions. The inferior alveolar nerve was located inferior to the roots in 52%, whereas an overlapped position was most common if the third molar was retained (90%), semi-retained (83%) or the age was less than 30 years (66%). Common incidental findings were apical radiolucencies, idiopathic osteosclerosis, and tooth fragments. Suboptimal patient positioning was found in one-third of the radiographs.

    CONCLUSIONS:  Panoramic radiography is a useful method to evaluate third molar prior to surgical removal and may be the only image required. Most incidental findings on panoramic radiographs does not seem to require any further odontological management.

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  • 7.
    Cederhag, Josefine
    et al.
    Malmö University, Faculty of Odontology (OD).
    Truedsson, Anna
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). University of Bergen, Norway.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Radiographic imaging in relation to the mandibular third molar: a survey among oral surgeons in Sweden2022In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 26, p. 2073-2083Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To query the experience of oral surgeons concerning referral routines and preferences for radiographic imaging modality before surgical removal of mandibular third molars and investigate factors that influence imaging modality preferences.

    MATERIALS AND METHODS: Members of the Swedish Association of Oral and Maxillofacial Surgeons (n = 280) were invited to participate in a web-based digital survey concerning their experiences and use of three imaging modalities in pre-surgical assessment of mandibular third molar removal. The survey comprised multiple-choice questions and four cases depicted in images; respondents reported whether they would supplement the cases with other images and, if so, from which modality.

    RESULTS: The response rate was 64%. Panoramic radiographs were most commonly used in pre-surgical planning (response options: always or often), significant difference between professions (p = 0.039), and considered to facilitate treatment planning (87%), as was CBCT (82%); for 51%, CBCT reduced post-operative complications. Preferred modality for localizing the mandibular canal was fairly evenly distributed and for non-complex case, significant difference between subgroups of OMFS surgeons was found (p = 0.003) as to preference for intraoral radiographs.

    CONCLUSIONS: A majority of respondents received a report within 2 weeks of their referral for CBCT and would read the report and view the images before surgery. Image modality preference differed depending on case complexity, with a greater perceived need for CBCT. Profession and practical experience affected choice.

    CLINICAL RELEVANCE: Choice of imaging modality in mandibular third molar assessment is also important from dose delivery and social economy standpoints.

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  • 8.
    Domic, Danijel
    et al.
    Malmö University, Faculty of Odontology (OD).
    Bertl, Kristina
    Malmö University, Faculty of Odontology (OD).
    Ahmad, Salman
    Malmö University, Faculty of Odontology (OD).
    Schropp, Lars
    Aarhus University.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Stavropoulos, Andreas
    Malmö University, Faculty of Odontology (OD).
    Accuracy of cone beam computed tomography is limited at implant sites with a thin buccal bone: A laboratory study2021In: Journal of Periodontology, ISSN 0022-3492, E-ISSN 1943-3670, Vol. 92, no 4, p. 592-601Article in journal (Refereed)
    Abstract [en]

    Background: To evaluate whether buccal bone thickness (BBT), implant diameter, and abutment/crown material influence the accuracy of cone beam computed tomography (CBCT) to determine the buccal bone level at titanium implants.

    Methods: Two implant beds (i.e., narrow and standard diameter) were prepared in each of 36 porcine bone blocks. The implant beds were positioned at a variable distance from the buccal bone surface, thus resulting in 3 BBT groups (i.e., > 0.5-1.0; > 1.0-1.5; > 1.5-2.0 mm). In half of the blocks, a buccal bone dehiscence of random extent ("depth") was created and implants were mounted with different abutment/crown material (i.e., titanium abutments with a metal-ceramic crown and zirconia abutments with an all-ceramic zirconia crown). The distance from the implant shoulder to the buccal bone crest was measured on cross-sectional CBCT images and compared to the direct measurements at the bone blocks.

    Results: While abutment/crown material and implant diameter had no effect on the detection accuracy of the buccal bone level at dental implants in CBCT scans, BBT had a significant effect. Specifically, when BBT was ≤ 1.0 mm, a dehiscence was often diagnosed although not present, i.e., the sensitivity was high (95.8%), but the specificity (12.5%) and the detection accuracy (54.2%) were low. Further, the average measurement error of the distance from the implant shoulder to the buccal bone crest was 1.6 mm.

    Conclusions: Based on the present laboratory study, BBT has a major impact on the correct diagnosis of the buccal bone level at dental titanium implants in CBCT images; in cases where the buccal bone is ≤ 1 mm thick, detection of the buccal bone level is largely inaccurate. This article is protected by copyright. All rights reserved.

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  • 9. Edén Strindberg, Jerker
    et al.
    Hol, Caroline
    Torgersen, Gerald
    Møystad, Anne
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Näsström, Karin
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Comparison of Swedish and Norwegian Use of Cone-Beam Computed Tomography: a Questionnaire Study2015In: Journal of Oral & Maxillofacial Research, ISSN 2029-283X, E-ISSN 2029-283X, Vol. 6, no 4, article id e2Article in journal (Refereed)
    Abstract [en]

    Objectives: Cone-beam computed tomography in dentistry can be used in some countries by other dentists than specialists in radiology. The frequency of buying cone-beam computed tomography to examine patients is rapidly growing, thus knowledge of how to use it is very important. The aim was to compare the outcome of an investigation on the use of cone-beam computed tomography in Sweden with a previous Norwegian study, regarding specifically technical aspects. Material and Methods: The questionnaire contained 45 questions, including 35 comparable questions to Norwegian clinics one year previous. Results were based on inter-comparison of the outcome from each of the two questionnaire studies. Results: Responses rate was 71% in Sweden. There, most of cone-beam computed tomography (CBCT) examinations performed by dental nurses, while in Norway by specialists. More than two-thirds of the CBCT units had a scout image function, regularly used in both Sweden (79%) and Norway (75%). In Sweden 4% and in Norway 41% of the respondents did not wait for the report from the radiographic specialist before initiating treatment. Conclusions: The bilateral comparison showed an overall similarity between the two countries. The survey gave explicit and important knowledge of the need for education and training of the whole team, since radiation dose to the patient could vary a lot for the same kind of radiographic examination. It is essential to establish quality assurance protocols with defined responsibilities in the team in order to maintain high diagnostic accuracy for all examinations when using cone-beam computed tomography for patient examinations.

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  • 10.
    Ekstam, Maria
    et al.
    Malmö University, Faculty of Odontology (OD).
    Sonesson, Mikael
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Effects of premolar extraction and orthodontic treatment in adolescents - a retrospective cephalometric study2023In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850Article in journal (Refereed)
    Abstract [en]

    Objectives: To evaluate the cephalometric effects of premolar extraction on skeletal and dental parameters, and on the soft tissues, in patients subsequently treated with fixed appliances. Prevalence and severity of external apical root resorption due to premolar extraction were also examined.Materials and methods: The dental records of 79 patients treated with fixed appliances were retrieved (groups: extraction, n = 19; non-extraction, n = 60). Pre- and post-treatment statuses of skeletal, dentoalveolar, and soft tissue variables were analyzed on lateral cephalograms to determine change. Periapical radiographs of the maxillary incisors were assessed for external apical root resorption using the Levander & Malmgren index. The t-test, Mann-Whitney U test, chi-squared test, and Kruskal-Wallis test were used to analyze the data. Significance was set at p < .05.Results: Changes in the protrusion and proclination of the incisors and in lip position were significantly different between the groups. Prevalence of external apical root resorption in the two groups was similar.Conclusions: Our findings suggest that extraction therapy affects dentoalveolar traits but not jaw position, nor the risk of root resorption, in patients treated with fixed appliances

  • 11.
    Feng, Xin
    et al.
    Univ Bergen, Fac Med, Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Chen, Yicheng
    Harbin Inst Technol, Sch Energy Sci & Engn, Xi Da Zhi St, Harbin 150001, Peoples R China..
    Cai, Weihua
    Northeast Elect Power Univ, Sch Energy & Power Engn, Changchun Rd 169, Changchun 132012, Peoples R China..
    Lie, Stein Atle
    Univ Bergen, Fac Med, Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). Univ Bergen, Fac Med, Dept Clin Dent, Arstadveien 19, N-5009 Bergen, Norway..
    Aerodynamic characteristics in upper airways among orthodontic patients and its association with adenoid nasopharyngeal ratios in lateral cephalograms2021In: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 21, no 1, article id 127Article in journal (Refereed)
    Abstract [en]

    Background Adenoid hypertrophy among orthodontic patients may be detected in lateral cephalograms. The study investigates the aerodynamic characteristics within the upper airway (UA) by means of computational fluid dynamics (CFD) simulation. Furthermore, airflow features are compared between subgroups according to the adenoidal nasopharyngeal (AN) ratios. Methods This retrospective study included thirty-five patients aged 9-15 years having both lateral cephalogram and cone beam computed tomography (CBCT) imaging that covered the UA region. The cases were divided into two subgroups according to the AN ratios measured on the lateral cephalograms: Group 1 with an AN ratio < 0.6 and Group 2 with an AN ratio >= 0.6. Based on the CBCT images, segmented UA models were created and the aerodynamic characteristics at inspiration and expiration were simulated by the CFD method for the two groups. The studied aerodynamic parameters were pressure drop (Delta P), maximum midsagittal velocity (V-ms), maximum wall shear stress (P-ws), and minimum wall static pressure (P-w). Results The maximum V-ms exhibits nearly 30% increases in Group 2 at both inspiration (p = 0.013) and expiration (p = 0.045) compared to Group 1. For the other aerodynamic parameters such as Delta P, the maximum P-ws, and minimum P-w, no significant difference is found between the two groups. Conclusions The maximum V-ms seems to be the most sensitive aerodynamic parameter for the groups of cases. An AN ratio of more than 0.6 measured on a lateral cephalogram may associate with a noticeably increased maximum V-ms, which could assist clinicians in estimating the airflow features in the UA.

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  • 12.
    Feng, Xin
    et al.
    Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Norway.
    Chen, Yicheng
    School of Energy Science and Engineering, Harbin Institute of Technology, People’s Republic of China.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Cai, Weihua
    School of Energy and Power Engineering, Northeast Electric Power University, People’s Republic of China.
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). Department of Clinical Dentistry, Faculty of Medicine, University of Bergen, Norway.
    The effect of rapid maxillary expansion on the upper airway's aerodynamic characteristics2021In: BMC Oral Health, ISSN 1472-6831, E-ISSN 1472-6831, Vol. 21, no 1, article id 123Article in journal (Refereed)
    Abstract [en]

    BackgroundThe effect of rapid maxillary expansion (RME) on the upper airway (UA) has been studied earlier but without a consistent conclusion. This study aims to evaluate the outcome of RME on the UA function in terms of aerodynamic characteristics by applying a computational fluid dynamics (CFD) simulation.MethodsThis retrospective cohort study consists of seventeen cases with two consecutive CBCT scans obtained before (T0) and after (T1) RME. Patients were divided into two groups with respect to patency of the nasopharyngeal airway as expressed in the adenoidal nasopharyngeal ratio (AN): group 1 was comprised of patients with an AN ratio<0.6 and group 2 encompassing those with an AN ratio<greater than or equal to>0.6. CFD simulation at inspiration and expiration were performed based on the three-dimensional (3D) models of the UA segmented from the CBCT images. The aerodynamic characteristics in terms of pressure drop (Delta P), maximum midsagittal velocity (V-ms), and maximum wall shear stress (P-ws) were compared by paired t-test and Wilcoxon test according to the normality test at T0 and T1.ResultsThe aerodynamic characteristics in UA revealed no statistically significant difference after RME. The maximum V-ms (m/s) decreased from 2.79 to 2.28 at expiration after RME (P=0.057).ConclusionThe aerodynamic characteristics were not significantly changed after RME. Further CFD studies with more cases are warranted.

  • 13.
    Feng, Xin
    et al.
    Univ Bergen, Fac Med, Dept Clin Dent, Bergen, Norway..
    Lie, Stein Atle
    Univ Bergen, Fac Med, Dept Clin Dent, Bergen, Norway..
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD). Univ Bergen, Fac Med, Dept Clin Dent, Bergen, Norway.
    Effect of Rapid Maxillary Expansion on Upper Airway Morphology: A Retrospective Comparison of Normal Patients versus Patients with Enlarged Adenoid Tissue2021In: Journal of Clinical Pediatric Dentistry, ISSN 1053-4628, E-ISSN 1557-5268, Vol. 45, no 3, p. 208-215Article in journal (Refereed)
    Abstract [en]

    Objectives The present study evaluated the effect of rapid maxillary expansion (RME) on the morphology of the upper airway (UA) by calculating cross-sectional areas and volumes and comparing the effect in patients with a normal-sized adenoid with the effect in patients with an enlarged adenoid. Study design: Seventeen patients met the inclusion criteria. We constructed 3D models of the UA on cone-beam computed tomography images to calculate cross-sectional areas and volumes at the levels of the nasopharyngeal, retropalatal, and retroglossal airways. Patients were divided into two groups: group 1 was comprised of patients with an adenoidal nasopharyngeal (AN) ratio < 0.6 and group 2 with an AN ratio >= 0.6. Paired samples t-tests assessed any area and volumetric changes of the UA after RME. Changes in degree of nasal obstruction, calculated as the AN ratio, was then compared for the two groups. An independent samples t-test compared volumetric changes in the nasopharynx between the two groups before and after RME. Results Changes in cross-sectional areas and volumes of the UA due to RME were not significant. The effects of RME on AN ratio (11 % vs 0 %) and nasopharyngeal volume (36.8 % vs 5.97%) were somewhat larger in group 2 patients who had adenoid-associated nasal obstruction compared with group 1 patients with a normal-sized adenoid; however, the differences were not significant. Conclusions After RME, the patients with an enlarged adenoid had more increases in nasopharyngeal volume compared with those with normal adenoid, despite there was no significant difference.

  • 14. Gross, Heidi
    et al.
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Detectability of normal anatomy in digital panoramic radiographs2014In: Swedish Dental Journal, ISSN 0347-9994, Vol. 38, no 4, p. 179-185Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate the image quality of digital panoramic radiographs and its correlation with the detectability of normal anatomical structures. The effects of image enhancement on the detectability were also studied. A total of 500 panoramic images (DICOM format) obtained with a storage phosphor-based digital system were evaluated. The image quality and the detectability of selected normal anatomical structures were evaluated in all images. Images with inadequate image quality were subjected to enhancement after which the detectability of the structures was re-evaluated. Only 9% of the images were classified as having adequate technical quality. The main sources of poor image quality were that the patient's tongue was not held against the palate and incorrect positioning of the patient. Not holding the tongue against the palate was found to have a negative impact on the detectability of maxillary structures. Of the images with horizontal positioning errors the patient's head was rotated to the left in 81% (70 images). The most effective form of enhancement was a combination of increased contrast and decreased brightness. Images in which the tongue was not held against the palate were partially improved, whereas images with positioning errors remained unaffected by this enhancement. In conclusion, most of the panoramic images showed some technical flaws. The marginal bone level and the maxillary area were the most difficult areas to reproduce. Retakes could be avoided in some cases by using image enhancement. However, this should not be regarded as an option to avoid poor image quality.

  • 15.
    Gudac, Jelena
    et al.
    Lithuanian University of Health Sciences, Lithuania.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Machiulskiene, Vita
    Lithuanian University of Health Sciences, Lithuania.
    Prognostic validity of the Periapical and Endodontic Status Scale for the radiographically assessed 2-year treatment outcomes in teeth with apical periodontitis: a prospective clinical study2021In: BMC Oral Health, ISSN 1472-6831, E-ISSN 1472-6831, Vol. 21, no 1, article id 354Article in journal (Refereed)
    Abstract [en]

    Background Endodontic treatment planning and treatment success evaluation are largely based on radiographic assessment of anatomical and treatment-related parameters of teeth with apical periodontitis (AP). This prospective clinical study aimed to assess radiographically the 2-year endodontic treatment outcomes for teeth with AP, and to evaluate prognostic validity of Periapical and Endodontic Status Scale (PESS). Methods A total of 128 patients, representing 176 teeth with AP were examined by cone-beam computed tomography at baseline and at 24 months after endodontic treatment. Treatment outcome was evaluated using estimates of periapical radiolucency and the relationship between anatomical structures and location. The strength of the associations between these and treatment-related parameters was tested by logistic regression analysis. PESS sensitivity and specificity were calculated for every treatment risk group (low, moderate, high) of teeth. Results One hundred and fifty-seven teeth, representing 350 root canals had a positive treatment outcome, while 19 teeth, representing 53 root canals had a negative treatment outcome at 24 months. The probability of negative outcome was 25 times higher in the moderate/high-risk group than in the mild-risk group of teeth (OR = 25.1; 95%CI [12.2-51.5]). Pre-treatment complications and retreatment cases with radiolucency were associated with negative outcomes (OR = 35.9; 95%CI [12.6-102.4]; OR = 26.437; 95%CI [10.9-64.1], respectively). PESS sensitivity and specificity was over 80% in all risk groups except for high risk group, due to very low number of cases. Conclusions Endodontic treatment outcome depends on the severity of periapical changes. The presence of complications and retreatment cases with periapical lesions are associated with negative treatment outcome. The PESS is a valid instrument to predict outcome of teeth with low-moderate treatment risk of AP.

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  • 16.
    Gudac, Jelena
    et al.
    Lithuanian Univ Hlth Sci, Fac Odontol, Clin Dent & Oral Pathol, Eiveniu Str 2, LT-50161 Kaunas, Lithuania..
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Maciulskiene, Vita
    Lithuanian Univ Hlth Sci, Fac Odontol, Clin Dent & Oral Pathol, Eiveniu Str 2, LT-50161 Kaunas, Lithuania..
    The Changes in Size of Periapical Lesions after Root Canal Treatments Assessed by Digital Periapical Radiography and Cone-Beam Computed Tomography: A 2-Years Prospective Clinical Study2022In: Medicina, ISSN 1010-660X, E-ISSN 1648-9144, Vol. 58, no 10, article id 1437Article in journal (Refereed)
    Abstract [en]

    Background and Objectives: There is limited information regarding comparison of long-term dynamics of periapical bone destruction estimated by digital periapical radiography (DPR) and by cone-beam computed tomography (CBCT). This study aimed to compare the radiographically assessed periapical changes of endodontically treated teeth over 2 years of follow-up and to analyse disagreements in periapical lesion size estimates around the same roots using DPR and CBCT. Materials and Methods: A total of 176 endodontically treated teeth, of 128 patients with apical periodontitis, were assessed by DPR and CBCT, at baseline and after 2 years. All periapical radiolucencies were categorised by severity (S0, S1, S2, S3) concerning their size. Descriptive statistics were used to report distribution of the radiolucencies at baseline and at follow-up, and their size transitions over 2 years. Site-specific comparison of the radiolucencies identified by two methods was performed using Z test and Pearson's chi-square test. Results: majority of the detected radiolucencies were scored as S0: 65% and 68% at baseline; 89% and 83% at follow-up, by DPR and CBCT, respectively. Site-specific score comparison showed that disagreements comprised 18% and 20% of the total number of radiolucencies detected by DPR and CBCT, respectively. There were more disagreements between DPR and CBCT within categories S1 and S2 + S3 compared to S0: at baseline, they comprised 17-33% and after two years 62-95% of all detected radiolucencies within the category. 65% of non-matching score transitions over two years occurred between S0 and S1. The CBCT-based evaluation resulted in negative treatment outcomes for 10 more root canals than the DPR-based result. Conclusions: Most remarkable disagreement between DPR and CBCT recordings was observed within the radiolucency categories S2 and S3. However, the diagnostic accuracy of both radiographic methods was questionable as it resulted in a high proportion of non-matching S0-S1 lesion transitions over 2 years.

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  • 17. Gudac, Jelena
    et al.
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Venskutonis, Tadas
    Puisys, Algirdas
    Machiulskiene, Vita
    Comparison of Selected Anatomical and Treatment-related Diagnostic Parameters Estimated by Cone-Beam Computed Tomography and Digital Periapical Radiography in Teeth with Apical Periodontitis2020In: Journal of Oral & Maxillofacial Research, ISSN 2029-283X, E-ISSN 2029-283X, Vol. 11, no 2, article id e4Article in journal (Refereed)
    Abstract [en]

    Objectives: To compare selected anatomical and treatment-related diagnostic parameters estimated by cone-beam computed tomography and by digital periapical radiography in teeth with apical periodontitis, and to evaluate reliability of different examiners in interpretation of images obtained by both methods.

    Material and Methods: Teeth with apical periodontitis were evaluated independently by 2 endodontists and 1 radiologist based on 128 cone-beam computed tomography (CBCT) and 162 digital periapical radiography (DPR) images. Anatomical (size, relation with root, location of periapical radiolucency) and treatment-related (canal obturation length, homogeneity, coronal seal) parameters were assessed. Fleiss kappa reflected inter-observer agreement while intra-examiner agreement was estimated by Cohen's kappa. McNemar and McNemar-Bowker tests served for evaluation of differences between CBCT- and DPR-based estimates.

    Results: Cohen's kappa ranged from 0.62 to 1 for all examiners. Fleiss kappa values were nearly perfect for majority of parameters. Diagnostic discrepancy between methods was found for size of radiolucency that in 15 - 17% cases was larger, and in 25 - 28% smaller in DPR than in CBCT images. DPR revealed 20% of root canals scored as non-obturated while in CBCT - obturation present. Canal obturation was rated as homogenous by CBCT, while absent or non-homogenous by DPR, in 17 - 23%, and 11 - 14% of cases, respectively. Radiologist detected more root perforations in CBCT than in DPR images.

    Conclusions: Good intra- and inter-examiner agreement for anatomical and treatment-related diagnostic parameters was achieved using cone-beam computed tomography and digital periapical radiography methods and demonstrated similar diagnostic capability, although variation regarding root perforations and canal obturation quality was observed.

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  • 18.
    Hajem, Samara
    et al.
    Malmö University, Faculty of Odontology (OD).
    Brogårdh-Roth, Susanne
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    CBCT of Swedish children and adolescents at an oral and maxillofacial radiology department: A survey of requests and indications.2020In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 78, no 1, p. 38-44Article in journal (Refereed)
    Abstract [en]

    This retrospective study investigated requests and indications for cone-beam computed tomography (CBCT) in children and adolescents over a 3-year period at one oral and maxillofacial radiology department. Specific aims were to determine what technical settings were used, which caregivers write the referrals, and how often and for what reasons re-exposure was necessary. Patients

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  • 19.
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Effect of two X-ray tube voltages on detection of approximal caries in digital radiographs. An in vitro study2011In: Clinical Oral Investigations, ISSN 1432-6981, E-ISSN 1436-3771, Vol. 15, no 2, p. 209-213Article in journal (Refereed)
    Abstract [en]

    This study evaluated the effect of two different tube voltages on clinicians' ability to diagnose approximal carious lesions in digital radiographs. One hundred extracted teeth were radiographed twice at two voltage settings, 60 and 70 kV, using a standardized procedure. Seven observers evaluated the radiographs on a standard color monitor pre-calibrated according to DICOM part 14. Evaluations were made at ambient light levels below 50 lx. All observations were analyzed with receiver operating characteristic curves. A histological examination of the teeth served as the criterion standard. A paired t test compared the effects of the two voltages. The significance level was set to p < 0.05. Weighted kappa statistics estimated intra-observer agreement. No significant difference in accuracy of approximal carious lesion diagnosis was found between the two voltage settings. But five observers rated dentin lesions on radiographs exposed at 70 kV better than on radiographs exposed at 60 kV. Intra-observer agreement differed from fair to moderate. There was no significant difference in accuracy of approximal carious lesion diagnosis between digital radiographs exposed with 60 or 70 kV.

  • 20.
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Quality Aspects of Digital Radiography in General Dental Practice2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    ABSTRACT The number of dentists who have converted from conventional film radiography to digital radiography continues to grow. A digital system has numerous advantages, but there are also many new aspects to consider. The overall aim of this thesis was to study how digital radiography was used in general dental practices. The specific aims were to study how different factors affected image quality. To determine whether there were any differences in image quality between conventional film radiographs and digital radiographs, 4863 images (540 cases) were evaluated. The cases had been sent to the Swedish Dental Insurance Office for prior treatment approval. The image quality of digital radiographs was found to be significantly lower than that of film radiographs. This result led to a questionnaire study of dentists experienced in digital radiography. In 2003, a questionnaire was sent to the 139 general practice dentists who worked with digital radiography in Skåne, Sweden; the response rate was 94%. Many general practice dentists had experienced several problems (65%), and less than half of the digital systems (40%) underwent some kind of quality control. One of the weaker links in the technical chain of digital radiography appeared to be the monitor. A field study to 19 dentists at their clinics found that the brightness and contrast settings of the monitors had to be adjusted to obtain the subjectively best image quality. The ambient light in the evaluation room was also found to affect the diagnostic outcome of low-contrast patterns in radiographs. To evaluate the effects of ambient light and technical adjustments of the monitor, a study using standardised set-ups was designed. Seven observers evaluated radiographs of 100 extracted human teeth for approximal caries under five different combinations of brightness and contrast settings on two different occasions with high and low ambient light levels in the evaluation room. The ability to diagnose carious lesions was found to be significantly better in a room with lower ambient light and on a monitor with well-adjusted brightness and contrast values than in a room with bright light and on an unadjusted monitor. In conclusion, many problems with dental digital radiography were identified. Knowledge of digital techniques and how to optimise each link in the system to maintain high radiographic quality at all times must be improved.

  • 21.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Hellén-Halme, Bengt
    Wenzel, Anne
    The effect of aging on luminance of standard liquid crystal display (LCD) monitors2011In: Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics, ISSN 1079-2104, E-ISSN 1528-395X, Vol. 112, no 2, p. 237-242Article in journal (Refereed)
    Abstract [en]

    Abstract OBJECTIVES: The aim of this study was to evaluate the luminance level of monitors as a function of the burning time of the lamp in the monitor and further to evaluate if different areas of the monitor varied in luminance levels at a specific time. MATERIAL AND METHODS: Nine standard liquid crystal display (LCD) monitor models, in total 180 monitors, were evaluated. The monitors' maximal luminance levels were measured, and the burning times of the lamps were noted. The estimated function between burning time and luminance was calculated. On 11 monitors, 9 areas distributed over the full screen were measured to evaluate the extent to which different areas had different luminance levels. RESULTS: Over time, the luminance decreased in all monitor models. No difference was found among the monitor models in how rapidly the luminance levels decreased. Different luminance values were found for different areas on the monitors, but no area deteriorated faster than another. CONCLUSIONS: Standard liquid crystal display monitors undergo gradual deteriorations in luminance levels over time, and these deteriorations are correlated with the time that the monitors have been switched on. The degradation in luminance is similar over all areas of the monitors.

  • 22.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Hol, Caroline
    Møystad, Anne
    Torgersen, Torgild
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Workflow and experiences in Norwegian clinics using dental CBCT units: A questionnaire study2013Conference paper (Other academic)
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  • 23.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Hollender, Lars
    Janda, Martin
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Web-based calibration of observers using MRI of the temporomandibular joint2012In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 41, no 8, p. 656-661Article in journal (Refereed)
    Abstract [en]

    Objectives Research diagnostic criteria for temporomandibular disorders (RDC/TMDs) were proposed in 1992 with the aim of standardizing and testing methods for diagnosing TMDs. RDC/TMDs have so far been lacking standardized methods for imaging and criteria for imaging diagnosis of disorders of the temporomandibular joint (TMJ). Criteria for disorders of the TMJ have recently been proposed for MRI. The aim of this study was to publish MR images of the TMJ on the web and to test the agreement of five observers using the criteria. Methods 20 cases of MRI of the TMJ were published on the web together with the criteria. The MR images were taken in closed and open mouth positions, and sagittal and coronal views. Five observers diagnosed disc position, disc shape, joint effusion and loose calcified bodies in the TMJ. Results In all cases except one, three or more observers agreed upon the diagnosis. All agreed on whether a loose calcified body was present or not. The second best agreement was obtained for disc position in the sagittal view, where all observers agreed in 16 of the 20 cases. For disc position in the coronal view and the evaluation of the disc shape, observer agreement was lower. Conclusion Criteria were useful in order to standardize and simplify evaluation and thereby probably increase the diagnostic outcome among different observers for MRI of the TMJ. We recommend that the criteria be used internationally to facilitate comparisons between different studies.

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  • 24.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Hänsel Petersson, Gunnel
    Malmö högskola, Faculty of Odontology (OD).
    Influence of education level and experience on detection of approximal caries in digital dental radiographs. An in vitro study2010In: Swedish Dental Journal, ISSN 0347-9994, Vol. 34, no 2, p. 63-69Article in journal (Refereed)
    Abstract [en]

    This study evaluated whether variations in education level and experience among dental staff influence the diagnostic accuracy of carious lesions on digital radiographs. Three student groups and a fourth group of general practitioners (Dentists) with more than five years of clinical experience participated in this study.The student groups were (i) dental students in their final (tenth) semester (DS-10), (ii) dental students in the sixth semester (DS-6) who just finished dental radiology training, and (iii) dental hygiene students (DHS) in their final (fourth) semester. Seven observers from each group participated. Standard radiographs of 100 extracted teeth (premolars and molars) were taken. The 28 observers evaluated the images for approximal carious lesions on a standard monitor. All evaluations were made in ambient light below 50 lux. Receiver operating characteristic curves were plotted to assess results. The standard criterion for healthy or carious lesions was a histological examination of sliced teeth. Kappa statistics evaluated intra-observer agreement. For carious lesions that had extended into the dentine, significant differences were found between (i) Dentists and all other groups, (ii) Dentists and DS-10 (p < 0.01), and (iii) Dentists and DS-6 and DHS (p < 0.001). Differences between DS-10 and DHS (p < or = 0.05) were also significant. In this study, education level and experience clearly influenced the diagnostic accuracy of approximal carious lesions that had extended into the dentine on digital radiographs.

  • 25.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Johansson, Curt
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Comparison of the performance of intraoral X-ray sensors using objective image quality assessment2016In: Oral surgery, oral medicine, oral pathology and oral radiology, ISSN 2212-4403, E-ISSN 2212-4411, Vol. 121, no 5, p. e129-e137Article in journal (Refereed)
    Abstract [en]

    Objectives. The main aim of this study was to evaluate the performance of 10 individual sensors of the same make, using objective measures of key image quality parameters. A further aim was to compare 8 brands of sensors. Study Design. Ten new sensors of 8 different models from 6 manufacturers (i.e., 80 sensors) were included in the study. All sensors were exposed in a standardized way using an X-ray tube voltage of 60 kVp and different exposure times. Sensor response, noise, low-contrast resolution, spatial resolution and uniformity were measured Results. Individual differences between sensors of the same brand were surprisingly large in some cases. There were clear differences in the characteristics of the different brands of sensors. The largest variations were found for individual sensor response for some of the brands studied. Also, noise level and low contrast resolution showed large variations between brands Conclusions. Sensors, even of the same brand, vary significantly in their quality. It is thus valuable to establish action levels for the acceptance of newly delivered sensors and to use objective image quality control for commissioning purposes and periodic checks to ensure high performance of individual digital sensors.

  • 26.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Johansson, Curt
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Response to the article "Comparison of the performance of intraoral X-ray sensors using objective image quality assessment"2016In: Oral surgery, oral medicine, oral pathology and oral radiology, ISSN 2212-4403, E-ISSN 2212-4411, Vol. 122, no 6, p. 784-785Article in journal (Refereed)
  • 27.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Johansson, Per-Magnus
    Håkansson, Jan
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Image Quality of Digital and Film Radiographs in Applications Sent to the Dental Insurance Office in Sweden for Treatment Approval2004In: Swedish Dental Journal, ISSN 0347-9994, Vol. 28, no 2, p. 77-84Article in journal (Other academic)
    Abstract [en]

    In July 2002, a new dental insurance program was introduced in Sweden. For all patients over 65 years, prior approval for all prosthetic work would need to be obtained from the Dental Insurance Office. From October to December 2002, 540 cases were randomly selected for evaluation from the 14,624 applications that had been sent from throughout Sweden to the Dental Insurance Office in Lund. Our aims were to appraise the quality of the radiographic examinations and to compare the quality of the digital with the film (X-ray film) radiographs. The radiographic examinations were evaluated as a whole in relation to the proposed treatment and in detail using specific criteria such as density, contrast, unsharpness, angulation, and receptor position error. The quality variables were evaluated as acceptable or unacceptable. A total of 4,687 intra-oral and 206 panoramic radiographs were evaluated. Thirteen per cent of the intra-oral radiographs and 9% of the panoramic radiographs were taken with a digital technique. Most of the digital radiographs—-70% of the intra-oral and 61% of the panoramic radiographs-—were submitted on microdisk. Twentyeight per cent of the intra-oral digital radiographs, however, were submitted on paper. The radiographic quality in 150 cases (28%) were found to be unacceptable for assessment of the proposed treatment. The most common error-—both in digital and X-ray film radiographs-—was in receptor position. Significantly more errors were found in the intra-oral digital radiographs compared to the radiographs taken with X-ray film. Most of the errors in the digital radiographs were detected in the paper copies. In conclusion, it is possible to improve the radiographic quality in applications for treatment approval, and the dentists had more difficulties with the digital technique than with X-ray film.

  • 28.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Lith, Agneta
    Carious lesions: diagnostic accuracy using pre-calibrated monitor in various ambient light levels: an in vitro study2013In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 42, no 8, article id 20130071Article in journal (Refereed)
    Abstract [en]

    Objectives: This study investigated the effect of different monitor calibration modes under various ambient lighting conditions on the ability of observers to recognize proximal carious lesions of varying depths. Methods: 7 observers evaluated 100 teeth for proximal carious lesions on standardized digital radiographs using 3 set-ups: (1) pre-calibrated monitor for high ambient light (higher than 1000 lux), (2) pre-calibrated monitor for low ambient light (less than 50 lux) and (3) Barten calibration (Digital Imaging and Communication in Medicine) on the monitor in dimmed ambient light (less than 50 lux). Receiver operating characteristic curves were plotted for all observations. The criterion standard was histological examination of the teeth. The effects of three conditions were compared using a paired t-test. The level of significance was set to p , 0.05. Results: No significant difference was found in diagnostic accuracy for the detection of any type of proximal carious lesions between the different calibration modes of the monitor according to different ambient light levels. Conclusions: There is no evidence that any difference between ambient light levels affects the ability to detect carious lesions in digital radiographs as long as the monitor was calibrated in accordance with the surrounding light level.

  • 29.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Lith, Agneta
    Effect of ambient light level at the monitor surface on digital radiographic evaluation of approximal carious lesions: an in vitro stud2012In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 41, no 3, p. 192-196Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: This study investigated how ambient light affects the diagnostic accuracy of dental carious lesions on monitors used in dental practice. Specifically, the aim was to evaluate whether a monitor hood for blocking excess ambient light increases practitioners' ability to accurately diagnose carious lesions on digital radiographs under bright ambient light conditions. METHODS: 7 observers evaluated approximal carious lesions on standardized digital radiographs of 100 teeth under 3 ambient light conditions: bright light (> 1000 lx) and dim light (<50 lx) with no monitor hood; and bright light with a hooded monitor. Receiver operating characteristic curves were plotted for all observations. The criterion standard was a histological examination of the teeth. A paired t-test compared the effects of the three lighting conditions. The level of significance was set to p <0.05. Weighted kappa statistics estimated intraobserver agreement. RESULTS: The diagnostic accuracy for dentine lesions was significantly higher in ambient light<50&hairsp ;lx than on monitors with and without a hood in ambient light>1000 lx. For all observers, diagnostic accuracy of dentine lesions under bright light was higher on a hooded monitor than on a monitor without a hood, but this difference was not significant. Intraobserver agreement varied from moderate to good. CONCLUSION: Diagnostic accuracy of those carious lesions that reached into the dentine was significantly higher in ambient light<50 lx than in ambient light>1000 lx. A hooded monitor in bright light was not as effective as a monitor without a hood in dim light

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  • 30.
    Hellén-Halme, Kristina
    et al.
    Malmö University, Faculty of Odontology (OD).
    Lith, Agneta
    Shi, Xie-Qi
    Reliability of marginal bone level measurements on digital panoramic and digital intraoral radiographs2020In: Oral Radiology/Springer, ISSN 0911-6028, E-ISSN 1613-9674, Vol. 36, no 2, p. 135-140Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The aim of this study was to evaluate the reliability of bitewing and panoramic radiographs in marginal bone level measurements in terms of inter- and intra-observer agreement. METHODS: Fifty paired bitewing and panoramic images were used. Eight observers measured marginal bone level at the mesial and distal surfaces of tooth 25 and tooth 35. Thus, in total 100 radiographs of 400 measurements were obtained for each observer. To evaluate intra-observer agreement, three observers re-evaluated the radiographs after a minimum of 1 month. Intra-class correlation coefficient (ICC) was applied to evaluate the inter- and intra-observer agreement. The t test was applied to assess possible difference in measurement between bitewing and panoramic radiographs. RESULTS: The mean ICC value of inter-observer agreement was 0.85 for bitewing and 0.66 for panoramic radiographs. The mean intra-observer agreement was 0.92 and 0.76 for bitewing and panoramic radiographs, respectively. There was no statistically significant difference between bitewing and panoramic radiographs in measurements of marginal bone level on maxillary tooth 25, whereas a statistically significant difference was found between the two image modalities on mandible tooth 35. CONCLUSION: Bitewing examination should be the choice of image modality for assessment of marginal bone level at premolar region due to good to excellent reliability and low radiation dose. However if a panoramic radiograph already exists, a rough estimation of marginal bone level at premolar region is clinically acceptable bearing in mind that the bone height of the mandible premolar region might be overestimated as compared to bitewing radiograph.

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  • 31.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Kristina
    The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging2013In: Journal of Oral & Maxillofacial Research, ISSN 2029-283X, E-ISSN 2029-283X, Vol. 4, no 3, article id e2Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in radiographs obtained using tube voltages of 60 and 70 kV. The aim of this study was, therefore, to evaluate the patient dose resulting from exposures at these tube voltages to obtain intraoral bitewing radiographs. MATERIAL AND METHODS: The absorbed dose distributions resulting from two bitewing exposures were measured at tube voltages of 60 and 70 kV using Gafchromic(®) film and an anatomical head phantom. The dose was measured in the occlusal plane, and ± 50 mm cranially and caudally to evaluate the amount of scattered radiation. The same entrance dose to the phantom was used. The absorbed dose was expressed as the ratio of the maximal doses, the mean doses and the integral doses at tube voltages of 70 and 60 kV. RESULTS: The patient receives approximately 40 - 50% higher (mean and integral) absorbed dose when a tube voltage of 70 kV is used. CONCLUSIONS: The results of this study clearly indicate that 60 kV should be used for dental intraoral radiographic examinations for approximal caries detection.

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  • 32.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, M
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Digital radiography in general dental practice: An investigation of the display monitor's effect on image quality2006Conference paper (Other academic)
    Abstract [en]

    Objectives: The aim of this study was to investigate the quality of radiographs acquired with digital technique in general dental practices, especially regarding factors related to the display monitor. A further aim was to evaluate how the enhancement programs were used by the dentists. Methods: Nine-teen general dental practitioners were visited in their clinics. Ambient light (illuminance) in the room was measured. Different technical parameters of the display monitor were noted. Test images and two phantoms, one low-contrast phantom and one line-pair resolution test phantom were used to control the digital system. The use of the enhancement program available in their equipment was evaluated by noting how the dentist used the program on a checking list which different functions were used. Results: The average illuminance in the operating room was 668 lux. All monitors were colour. The study showed that the amount of “light percentage” set initially in the monitor had to be decreased with in average 17% to optimise the results of the test images. The contrast factor was decreased with in average 10%. The general dental practitioners mostly used the possibility to alter brightness and contrast of the different phantom images to obtain the subjectively best image Conclusion: There is a need to improve the knowledge how to handle the digital equipment in general dental practice. A monitor with good quality has to be a given priority as well as ambient light conditions when you read radiographs. There is a need to develop a standardised quality control for digital dental radiography.

  • 33.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Digital radiography in general dental practice. A field study2007In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 36, no 5, p. 249-255Article in journal (Refereed)
    Abstract [en]

    Abstract Objectives: The aim of this study was to conduct a field study to survey the performance of digital radiography and how it was used by dentists in general dental practice. Methods: Nineteen general dental practitioners were visited at their clinics. Ambient light (illuminance) was measured in the rooms where the monitors were placed. Different technical display parameters were noted. Test images and two phantoms—one low-contrast phantom and one line-pair resolution phantom—were used to evaluate the digital system. How the dentists used the enhancement program was investigated by noting which functions were used. Results: Average illuminance in the operating room was 668 lux (range 190–1250 lux). On radiographs of the low-contrast phantom taken at the clinic, the ability to observe the holes decreased as illuminance increased. On average, the “light percentage” initially set on the monitor had to be decreased by 17% and contrast by 10% to optimise the display of the test images. The general dental practitioners used the enhancement programs most often to alter brightness and contrast to obtain the subjectively best image. Large differences between the clinics were noted. Conclusion: Knowledge of how to handle digital equipment in general dental practice should be improved. A calibrated monitor of good quality should be a given priority, as should proper ambient light conditions. There is a need to develop standardised quality controls for digital dental radiography. Key-words: display monitor, enhancement program, digital radiography, quality

  • 34.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Effect of monitors on approximal caries detection in digital radiographs—standard versus precalibrated DICOM part 14 displays: An in vitro study2009In: Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics, ISSN 1079-2104, E-ISSN 1528-395X, Vol. 107, no 5, p. 716-720Article in journal (Refereed)
    Abstract [en]

    Objectives. The aim of this study was to evaluate if different ways of adjusting brightness and contrast of monitors with different technical standards influence the diagnosis of carious lesions in digital radiographs. Study design. One hundred extracted teeth (premolars and molars) were radiographed. Seven observers evaluated images for approximal carious lesions on 3 monitors: a standard color monitor with brightness and contrast manually adjusted for viewing radiographs, a Digital Imaging and Communication in Medicine (DICOM) part 14 precalibrated color monitor, and a DICOM part 14 precalibrated monochromatic monitor. All evaluations were made in ambient light <50 lux. Receiver operating characteristic curves were plotted to evaluate results. The standard criterion was a histologic examination of sliced teeth. Kappa statistic evaluated intraobserver agreement. Results. No significant difference in accuracy of approximal carious lesion diagnosis was found between the monitors. Intraobserver agreement varied between fair and good. Conclusion. No differences that could affect clinicians’ abilities to detect carious lesions in digital radiographs existed between the standard monitor and the color and monochrome DICOM part 14 precalibrated monitors.

  • 35.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Digital röntgen2008In: Digitala kliniken, Gothia Förlag AB, 2008, p. 29-41Chapter in book (Other academic)
  • 36.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Effect of ambient light and monitor brightness and contrast settings on the detection of approximal caries in digital radiographs.2007Conference paper (Refereed)
    Abstract [en]

    Abstract Aims: The aim of this study was to investigate how brightness and contrast settings of the display monitor and ambient light level (illuminance) in the viewing room affect the clinician’s ability to diagnose carious lesions in digital radiographs. Methods: Standardised radiographs were taken of 100 extracted teeth. Seven observers evaluated the images for approximal carious lesions twice, once under 500-lux and once under 1000-lux room illumination. Radiograph brightness and contrast were varied ±50% and ±6%, respectively, to mimic normal limits of monitor adjustment by an inexperienced user and one optimal setting. Thus, five radiographs of each tooth were made. Receiver operating characteristic (ROC) analyses were performed. Histologic examinations of the teeth served as the criterion standard. A paired t-test was used to evaluate whether differences in the areas under the ROC curves were significant, and kappa was used to evaluate intra-observer agreement. Results: When a monitor with optimal brightness and contrast settings was used to detect approximal carious lesions, ambient light levels less than 50 lux were significantly better than levels above 1000 lux (dentine and enamel lesions, p<0.01; dentine lesions, p<0.02). Increasing the contrast setting of the monitor by 6% did not change these results; 50 lux was still significantly better than 1000 lux (enamel lesions, p<0.01; dentine and enamel lesions, p<0.02) for evaluating radiographs. Intra-observer agreement differed from fair to good. Conclusion: Reducing ambient light to less than 50 lux significantly increased the accuracy of diagnosing approximal carious lesions on a monitor with an optimal brightness setting and an optimal or slightly higher than optimal contrast setting.

  • 37.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Warfvinge, Gunnar
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Effect of ambient light and monitor brightness and contrast settings on the detection of approximal caries in digital radiographs: an in vitro study2008In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 37, no 7, p. 380-384Article in journal (Refereed)
    Abstract [en]

    Objectives: The aim of this study was to investigate how brightness and contrast settings of the display monitor and ambient light level (illuminance) in the viewing room affect the clinician's ability to diagnose carious lesions in digital radiographs. Methods: Standardized radiographs were taken of 100 extracted teeth. Seven observers evaluated the images for approximal carious lesions twice, once under 50 lux and once under 1000 lux room illumination. Monitor brightness and contrast were varied ±50% and ±6%, respectively, to mimic the normal limits of monitor adjustment by an inexperienced user and one optimal setting. This was done by adjusting radiograph brightness and contrast by ±25%. Thus, five radiographs of each tooth were evaluated. Receiver operating characteristic (ROC) analyses were performed. Histological examinations of the teeth served as the criterion standard. A paired t-test was used to evaluate whether differences in the areas under the ROC curves were significant and kappa was used to evaluate intraobserver agreement. Results: When a monitor with optimal brightness and contrast settings was used to detect approximal carious lesions, ambient light levels less than 50 lux were significantly better than levels above 1000 lux (dentin and enamel lesions, P < 0.01; dentin lesions, P < 0.02). Increasing the contrast setting of the monitor by 6% did not change these results; 50 lux was still significantly better than 1000 lux (enamel lesions, P < 0.01; dentin and enamel lesions, P < 0.02) for evaluating radiographs. Intraobserver agreement differed from fair to good. Conclusions: Reducing ambient light to less than 50 lux significantly increased the accuracy of diagnosing approximal carious lesions on a monitor with an optimal brightness setting and an optimal or slightly higher than optimal contrast setting.

  • 38.
    Hellén-Halme, Kristina
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Rohlin, Madeleine
    Malmö högskola, Faculty of Odontology (OD).
    Petersson, Arne
    Malmö högskola, Faculty of Odontology (OD).
    Dental digital radiography: a survey of quality aspects2005In: Swedish Dental Journal, ISSN 0347-9994, Vol. 29, no 2, p. 81-87Article in journal (Refereed)
    Abstract [en]

    The aim was to evaluate the experiences of Swedish general dental practitioners (GDPs) with digital radiography and their opinion on the same, particularly regarding quality issues. A letter was sent to all GDPs in private care in Region Skåne, Sweden, asking whether they used digital radiography (n=513). The response rate was 79%. The number of private GDPs who replied that they used digital radiography was 106. The Public Dental Service in Region Skåne listed 33 GDPs who worked with digital radiography. Based on these answers, a questionnaire was sent to the GDPs working with digital radiography (n=139). The questionnaire comprised 27 questions about the dentists, the system of intra-oral digital radiography, and the GDPs’ experiences of and opinions on issues regarding image quality and quality control. The response rate to the questionnaire was 94%. Almost all, 92%, worked with charge-coupled device (CCD) and complementary metal oxide semiconductor (CMOS) sensors. Most GDPs were satisfied with their digital radiographic system. The majority (65%) experienced problems. Detector failure and trouble with the software were common. The GDPs wrote that they used lower exposure times in digital radiography than traditional film radiography. The estimated reduction in exposure time was said to be between 51% and 75%. Thirtyfive per cent continued to use film parallel with digital radiography. The answers indicated that less than half of the equipment (40%) underwent quality control. Quality controls, when conducted, were undertaken once or twice a year, mainly by technicians from the companies that had sold the digital equipment. Based on the results of the questionnaire, there seems to be a need to improve the maintenance and the quality of digital radiography. It is also important that the GDPs become more aware of the problems that can occur when a new technique is introduced and that they develop the skills to handle these problems.

  • 39. Hol, Caroline
    et al.
    Hellen-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Torgersen, Gerald
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Møystad, Anne
    How do dentists use CBCT in dental clinics? A Norwegian nationwide survey2015In: Acta Odontologica Scandinavica, ISSN 0001-6357, E-ISSN 1502-3850, Vol. 73, no 3, p. 195-201Article in journal (Refereed)
    Abstract [en]

    Objectives. Cone beam computed tomography (CBCT) was introduced to Norwegian dental clinics in 2007. The aim of the study was to investigate how dental clinics use this imaging modality, including factors related to workflow and image quality, and to evaluate dentists' opinions on and experiences of using it. Materials and methods. A web-based 59-item questionnaire regarding the clinical use of CBCT was sent to all 39 CBCT clinics in Norway. Results. Twenty-nine clinics (74%) responded. Most respondents (93%) were from clinics with more than one dentist and 83% had at least one specialist. All clinics had digital intraoral x-ray receptors and all but one had panoramic imaging. The most common indications for CBCT were implant treatment planning (34% of all clinics) and localization of impacted teeth (43% of specialist clinics). Seventy-two per cent of clinics reported an average of four or fewer CBCT examinations each week and 83% of respondents were subjectively satisfied with the image quality. The most commonly used enhancement functions were contrast (97%), brightness (90%) and zoom (86%). Conclusions. The Norwegian CBCT clinics surveyed were fully digitized and had multiple dentists. Periodontists and oral and maxillofacial surgeons were the most frequent specialties represented in the clinics. Clinics with only dental specialists performed more CBCT examinations/week than clinics with general practitioners or both general practitioners and specialists. The most common indications for CBCT examinations were related to treatment planning. This study found some challenges related to image quality and communication within the radiological team.

  • 40.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Ekberg, Ewa Carin
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Web-based educational programme for temporomandibular joint assessment with cone-beam computed tomography.2020In: Journal of Oral Rehabilitation, E-ISSN 1365-2842, Vol. 47, no 11, p. 1330-1336Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To develop and evaluate an educational web-based program for temporomandibular joint (TMJ) assessment using cone-beam computed tomography (CBCT).

    METHODS: A web-based educational program was designed for TMJ assessment using CBCT images. Fifteen CBCT cases of the TMJ (three-dimensional reconstructed volumes) and an assessment module based on image analysis criteria in the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) were added to the program. Thirty-six undergraduate dental students were invited to test the program by assessing all cases twice: before and after 2 months of training. Participants submitted written subjective evaluations of the program.

    RESULTS: The web-based program can be accessed on Malmö University webpage (www.cbct-tmj.mau.se). Despite limited CBCT learning in their undergraduate training and not using the program in the 2-month interval, the students were able to correctly diagnose 80% of the cases at the second assessment. Their diagnoses, however, did not differ significantly from the first assessment. Overall, the students were satisfied with the program and considered it user friendly.

    CONCLUSION: The web-based educational program that was developed in the present study and tested by dental students could be a useful educational tool for TMJ assessment using CBCT.

  • 41.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Assessment of a training programme on detection of temporomandibular joint osseous changes applying pre-defined 2D multiplane cone beam computed tomography reconstructions2018In: Journal of Oral Rehabilitation, E-ISSN 1365-2842, Vol. 45, no 4, p. 282-288Article in journal (Refereed)
    Abstract [en]

    Objectives Osseous changes in temporomandibular joint disorders (TMD) are common indications for cone beam computed tomography (CBCT). The number of such cases is increasing while a number of qualified oral radiologists is limited. This study investigated the usefulness of a training programme for general dental practitioners (GDPs) regarding temporomandibular joint (TMJ) osseous changes detection in CBCT images. Methods We selected CBCT images of 35 TMD cases and chose 5 of them to use in training 7 GDPs on detecting osseous changes in the TMJ. In evaluation directly following training, GDPs assessed the 30 remaining cases. Three qualified radiologists served as reference standard. A 2-month follow-up of training comprising evaluation of the same cases. The cases are assessed according to Ahmad etal (Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 107, 2009, 844) protocol of TMJ osseous changes in CBCT images. ResultsSensitivity and specificity of the CBCT protocol were high, except for some criteria that did not appear in the cases. Average observer sensitivity was 65% while specificity was 87%. Average correct individual response rate was 84%. Mean agreement among the GDPs was 73%. Observer performance had improved at the 2-month follow-up. Conclusion The present educational programme could be a helpful material on recognising possible osseous changes of TMJ and it can be used as a part of a training programme for GDP and for specialist candidates.

  • 42.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Absorbed dose distributions for cone beam computed tomography examinations of the temporomandibular joint in phantoms of an adult and child2018Conference paper (Other academic)
    Abstract [en]

    Introduction To measure absorbed dose with high spatial resolution we have used Gafchromic film which gives an analog-looking dose distribution image compared to point measurements, e.g. TLDs. CBCT examinations of TMJs will produce dose distributions with very steep dose gradients. Over a distance of 2 mm, the absorbed dose can increase/decrease more than a factor of 10. Point measurements using 3x3 mm TLDs will give dose values with high uncertainty when placed in areas with steep dose gradients. Aim The aim was to map the absorbed dose distributions with Gafchromic film, for TMJ investigations using adult and child phantoms. Another aim was to analyze the difference of dose distributions in sensitive organs/tissues between the phantoms. Material and methods Gafchromic films were placed between selected layers of the two head phantoms. The number of films was chosen to well cover the height of the CBCT volume used. The films were scanned in a flatbed scanner and the net pixel values were converted to absorbed dose using a calibration curve. Clinically used examination protocols were applied for three different CBCT units. Outlines of organs/tissues considered at risk were superimposed on the dose distributions. Maximum, minimum and mean doses were calculated. Also, the integrated dose in the phantom was calculated to reflect the total radiation load. Preliminary results and conclusion For CBCT examinations, dose gradients are steep in many organs/tissues considered at risk. Measuring dose distributions with high spatial resolution will give a solid foundation for calculating mean doses in those organs/tissues both for children and adults and will also facilitate comparisons of different examination protocols and of different CBCT units.

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  • 43.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Dose distributions in adult and child head phantoms for panoramic and cone beam computed tomography imaging of the temporomandibular joint2020In: Oral surgery, oral medicine, oral pathology and oral radiology, ISSN 2212-4403, E-ISSN 2212-4411, Vol. 130, no 2, p. 200-208, article id S2212-4403(20)30017-1Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: The aim of this study was to map and compare the distributions of absorbed doses with Gafchromic film for panoramic radiography and cone beam computed tomography (CBCT) examinations of the temporomandibular joint (TMJ) by using adult and child phantoms.

    STUDY DESIGN: Gafchromic films were placed at 5 selected levels of anthropomorphic head phantoms of an adult and a child. Clinical protocols for panoramic and CBCT imaging of the TMJ were used for three 2-dimensional or 3-dimensional dental x-ray units. Mean absorbed doses in a set of radiosensitive tissues within the oral and maxillofacial regions were estimated.

    RESULTS: The absorbed doses varied considerably among and within radiosensitive tissues. The bone surface and the salivary glands received the highest absorbed doses compared with other tissues, in both panoramic and CBCT examinations of the TMJ. The radiation burden to the adult phantom was generally higher than that to the child phantom. Small right and left fields of view were associated with lower amounts of radiation, in contrast to a single larger field of view.

    CONCLUSIONS: The absorbed dose within all radiosensitive tissues varied considerably in relation to examination type, x-ray unit, clinical settings, and patient age. The mean doses were smaller when using 2 (bilateral) 4 × 4 cm volumes than with use of one 14 × 5 cm volume.

  • 44.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Evaluation of a low-dose protocol for cone beam computed tomography of the temporomandibular joint2021In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 50, no 1Article in journal (Other academic)
  • 45.
    Iskanderani, Durer
    et al.
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö University, Faculty of Odontology (OD).
    Alstergren, Per
    Malmö University, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Evaluation of a low-dose protocol for cone beam computed tomography of the temporomandibular joint.2020In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 49, no 6, article id 20190495Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Evaluation of cone beam CT (CBCT) examination with a low-dose scanning protocol for assessment of the temporomandibular joint (TMJ).

    METHODS: 34 adult patients referred for CBCT imaging of the TMJ underwent two examinations with two scanning protocols, a manufacturer-recommended protocol (default) and a low-dose protocol where the tube current was reduced to 20% of the default protocol. Three image stacks were reconstructed: default protocol, low-dose protocol, and processed (using a noise reduction algorithm) low-dose protocol. Four radiologists evaluated the images. The Sign test was used to evaluate visibility of TMJ anatomic structures and image quality. Receiver operating characteristic analyzes were performed to assess the diagnostic accuracy. κ values were used to evaluate intraobserver agreement.

    RESULTS: ) averaged for the low-dose and processed protocols, according to all observers, were 0.931 and 0.941, respectively. Intraobserver agreement was good to very good.

    CONCLUSION: For the CBCT unit used in this study, the low-dose CBCT protocol for TMJ examination was diagnostically comparable to the manufacturer-recommended protocol, but delivered a five times lower radiation dose. There is an urgent need to evaluate protocols for CBCT examinations of TMJ in order to optimize them for a radiation dose as low as diagnostically acceptable (the as low as diagnostically acceptable principle recommended by NCRP).

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  • 46. Liljeholm, Robert
    et al.
    Kadesjö, Nils
    Benchimol, Daniel
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Shi, Xie-Qi
    Cone-beam computed tomography with ultra-low dose protocols for pre-implant radiographic assessment: An in vitro study.2017In: European Journal of Oral Implantology, ISSN 1756-2406, E-ISSN 1756-2414, Vol. 10, no 3, p. 351-359Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To evaluate the ultra-low dose scanning protocols of a newly developed CBCT for pre-implant radiographic assessment. MATERIALS AND METHODS: A total number of 32 CBCT scans were exposed at 90 kV using ProMax 3D's standard (GS) and three ultra-low dose scanning protocols: high, mid and low definition (UL-HD, UL-MD and UL-LD) on eight human dry skulls with simulated soft tissue. The mAs values and the voxel size were 96mAs/200 µm, 28mAs/150 µm, 22.4mAs/200 µm and 7.5mAs/400 µm for scanning protocols GS, UL-HD, UL-MD and UL-LD, respectively. The overall image quality and the precision of anatomical landmarks were assessed on a 4-rank ordinal scale by seven observers. Logistic regression analysis and post-hoc Scheffé test were applied to analyse possible differences in image quality and recognition of the anatomical structures for the three ultra-low dose protocols, compared with the standard protocol. Additionally, observers performed bone quality assessment and bone quantity measurement at 96 predefined 2D cross-sectional images. A Pearson Chi-square test and a paired t-test were used to analyse assessed bone quality and quantity using the four scanning protocols respectively. RESULTS: For the CBCT unit, ProMax 3D, UL-LD was not diagnostically acceptable for pre-implant assessment, whereas the UL-HD and UL-MD were diagnostically acceptable regarding overall image quality, visibility of most anatomical structures and bone quality assessment. However, to recognise the border of mandibular canal and the border of maxillary sinus, standard protocol may be indicated for some cases. No statistically significant differences in bone height measurement were found when applying standard protocol and the three ultra-low dose protocols. CONCLUSIONS: Low-dose scanning protocols may be applied for pre-implant radiographic assessment, although image quality can be hampered if the radiation exposure is too low and the voxel size too large. PMID: 28944361

  • 47.
    Milosavljevic, Aleksandar
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Westerberg, Jane
    Hellen-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    Diagnostic accuracy of carious lesions in digital radiographs at a public dental clinic - can it be improved by optimizing viewing conditions and further education?2016In: Swedish Dental Journal, ISSN 0347-9994, Vol. 40, no 2, p. 235-242Article in journal (Refereed)
    Abstract [en]

    Objective:This study investigated the diagnostic accuracy of digital dental radiography for detecting carious lesions on approximal surfaces before and after optimization of the environment, and after joint training on evaluation and review of x-rays. A further aim was to evaluate differences in diagnostic accuracy between general dental practitioners (GDPs) and dental hygienists (DHs). Materials and methods:One hundred extracted teeth (premolars and molars) underwent standardized radiography. Eleven participants (seven GDPs and four DHs) evaluated digital images for approximal carious lesions in three sessions: (1) at current conditions with no optimization or further training, (2) under optimized viewing conditions, and (3) under optimized viewing conditions after a short educational session. Receiver operating characteristic curves were used to evaluate the results. Histological evaluation was made and served as a criterion standard for differentiating sound teeth and teeth with carious lesions. Kappa statistics evaluated intra-observer agreement. Results: Diagnostic accuracy in the GDP group differed significantly for all types of carious lesions between the first and third evaluations (p=0.002), and also between the second and third (p=0.015). Diagnostic accuracy also differed significantly for carious lesions into the dentin between the first and third evaluations (p=0.010) and between the second and third (p=0.015). Conclusion: Most of the staff had optimized the environment when evaluating digital radiographs. A short educational session highlighting the difficulty of caries diagnostics in digital dental radiography can increase diagnostic accuracy. Diagnostic accuracy in the detection of approximal carious lesions on digital radiographs did not differ between GDPs and DHs.

  • 48.
    Olsson, Lars
    et al.
    Malmö högskola, Faculty of Odontology (OD).
    Nilsson, Mats
    Malmö högskola, Faculty of Odontology (OD).
    Svensson, Björn
    Hellén-Halme, Kristina
    Malmö högskola, Faculty of Odontology (OD).
    The effect of anatomical noise on perception of low contrast in intra-oral radiographs: an in vitro study2016In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 54, no 4, article id 20150402Article in journal (Refereed)
    Abstract [en]

    and discussed of these is random noise. However, recent research has shown that the projected anatomy contributes substantially to noise, especially when detecting low-contrast objects in the images. Our aim, therefore, was to evaluate the extent to which overprojected anatomical noise affects the detection of low-contrast objects in intra-oral images. Methods: Our study used four common sensor models. With each sensor, we took four series of images, three series with and one series without an anatomical phantom present. In each series, we exposed a low-contrast phantom at 18 different exposure times using a standardized method. 4 observers evaluated all 288 images. Results: The low-contrast characteristics differed substantially when imaging low contrast on a homogeneous background compared with imaging low contrast when an anatomical phantom was present. For three of the sensors, optimal exposure times for low-contrast imaging were found, while the fourth sensor displayed a completely different behaviour. Conclusions: Calibrating the low-contrast properties of an imaging system using lowcontrast objects on a homogeneous background is not recommended. On an anatomical background, low-contrast properties are completely different, and these will mimic the clinical situation much more closely, directing the operator how to best use the system. There is a clear demand for further research on this subject. Dentomaxillofacial Radiology (2016) 45, 20150402. doi: 10.1259/dmfr.20150402

  • 49.
    Shi, Xie-Qi
    et al.
    Univ Bergen, Sect Oral Maxillofacial Radiol, Dept Clin Dent, Fac Med, Bergen, Norway..
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Nilsson, Mats
    Skane Univ Hosp, Dept Med Radiat Phys, Malmo, Sweden..
    In response to the letter to the editor regarding "A comparative study on image quality of two digital intraoral sensors-Methodological, ethical and statistical issues"2020In: Dento-Maxillo-Facial Radiology, ISSN 0250-832X, E-ISSN 1476-542X, Vol. 49, no 4Article in journal (Other academic)
  • 50.
    Sonesson, Mikael
    et al.
    Malmö University, Faculty of Odontology (OD).
    Al-Qabandi, Fahad
    Malmö University, Faculty of Odontology (OD).
    Mansson, Sven
    Lund Univ, Skane Univ Hosp, Dept Translat Med, Med Radiat Phys, Malmo, Sweden..
    Abdulraheem, Salem
    Malmö University, Faculty of Odontology (OD).
    Bondemark, Lars
    Malmö University, Faculty of Odontology (OD).
    Hellén-Halme, Kristina
    Malmö University, Faculty of Odontology (OD).
    Orthodontic appliances and MR image artefacts: An exploratory in vitro and in vivo study using 1.5-T and 3-T scanners2021In: Imaging Science in Dentistry, ISSN 2233-7822, E-ISSN 2233-7830, Vol. 51, no 1, p. 63-71Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of this study was to assess the artefacts of 12 fixed orthodontic appliances in magnetic resonance images obtained using 1.5-T and 3-T scanners, and to evaluate different imaging sequences designed to suppress metal artefacts. Materials and Methods: In vitro, study casts of 1 adult with normal occlusion were used. Twelve orthodontic appliances were attached to the study casts and scanned. Turbo spin echo (TSE), TSE with high readout bandwidth, and TSE with view angle tilting and slice encoding for metal artefact correction were used to suppress metal artefacts. Artefacts were measured. In vivo, 6 appliances were scanned: 1) conventional stainless-steel brackets; 2) nickelfree brackets; 3) titanium brackets; 4) a Herbst appliance; 5) a fixed retainer; and 6) a rapid maxillary expander. The maxilla, mandible, nasopharynx, tongue, temporomandibular joints, and cranial base/eye globes were assessed. Scores of 0, 1, 2, and 3 indicated no artefacts and minor, moderate, and major artefacts, respectively. Results: In vitro, titanium brackets and the fixed retainer created minor artefacts. In vivo, titanium brackets caused minor artefacts. Conventional stainless-steel and nickel free brackets, the fixed retainer, and the rapid maxillary expander caused major artefacts in the maxilla and mandible. Conventional stainless-steel and nickel-free brackets caused major artefacts in the eye globe (3-T). TSE with high readout bandwidth reduced image artefacts in both scanners. Conclusion: Titanium brackets, the Herbst appliance, and the fixed retainer caused minor artefacts in images of neurocranial structures (1.5-T and 3-T) when using TSE with high readout bandwidth.

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