Aim: This study aimed to evaluate the bond strength of adhesively cemented lithium disilicate restorations to dentin by applying different pretreatments and cleaning methods.

Material and Methods: Twenty-five human posterior teeth were mounted in an acrylic mold, flattened to expose mid-coronal dentin, and divided into five groups based on different pretreatments and cleaning methods prior to adhesive cementation. After cementation, the teeth were sectioned to obtain 1 mm² specimens, yielding 15 specimens in each group that were subjected to aging and thermocycling process, followed by a microtensile bond test and failure mode assessment.

Results: The highest bond strength values were in the control group and in the group that was treated with fluoride and where the temporary cement was removed using pumice, whereas the lowest values were in groups that were cleaned by excavator irrespective of whether they were treated with fluoride or not. However, all groups showed mainly cohesive failure without any statistically significant differences.

Conclusions: To eliminate any possible negative impact of eugenol on adhesion to dentin, surface cleaning by rotational brush and pumice is recommended prior to cementing lithium disilicate restorations.

Objective. The aim of the study was to examine the fracture strength of fully anatomical monolithic high translucent Y-TZP, yttria-stabilized tetragonal zirconia polycrystal, crowns and to compare them with monolithic low translucent Y-TZP crowns in different thicknesses. Materials and methods. 80 standardized crowns were made out of a master model resembling a first mandibular molar made in composite material; 40 crowns made of Lava Zirconia by 3M ESPE, a monolithic low translucent Y-TZP material, and 40 crowns made of Lava Plus by 3M ESPE, a monolithic high translucent Y-TZP material. In each group ten crowns of the thicknesses 1.0 mm, 0.7 mm, 0.5 mm and 0.3 mm were made. All crowns underwent thermocycling and preload to simulate aging and normal wear. Finally the specimens were placed in a testing jig and underwent load to fracture. Results. No significant difference was found when comparing the two materials. When comparing the materials in each thickness a significant difference was found in the 0.5 mm group where the high translucent YTZ-P had a higher mean fracture strength value. A significant difference was seen between the different thicknesses within both groups. The strength increased with added thicknesses. Conclusions. The low translucent and high translucent monolithic YTZ-P perform equally well. The use of high translucent monolithic Y-TZP could result in more aesthetic results and the minimal invasive preparation could lead to a reduction in biological complications. This could be beneficial for the patient since the results suggest that even a thin restoration sustains reasonable load in an in vitro environment. Clinical studies are needed to confirm this suggestion.

Purpose To evaluate the influence of the framework designs on the stress distribution within tooth-supported partially veneered fixed dental prostheses (FDPs) made of translucent zirconia under simulated loads using a three-dimensional finite element analysis (3D-FEA). Material and Methods For a linear 3D-FEA, simplified 3D solid models of prepared abutment teeth (first premolar and first molar) with different 3-unit FDPs were created. The models with different FDP designs-monolithic zirconia (control); semi-monolithic zirconia with 0.3 mm veneer thickness (SM0.3); semi-monolithic zirconia with 0.5 mm veneer thickness (SM0.5); semi-monolithic zirconia with 0.5 mm veneer thickness supported with cap design (SMC), and semi-monolithic zirconia with 0.5 mm veneer thickness supported with wave design (SMW)-were analyzed using 3D-FEA. The elastic properties of the components (bone, dentine, cement, translucent zirconia, and veneering porcelain) were obtained from the published data for FEA. Simulated static loading forces (300 N) were applied at 10 degrees oblique direction over six points in the occlusal surfaces of the FDPs. Maximum principal stress, shear stress, and safety factor were calculated and analyzed among the different models. Results Semi-monolithic with cap design showed the smallest maximum principal stress levels in the veneering porcelain compared to all other models (SM0.3, SM0.5, SMW). The SM0.3 had lower maximum principal stress levels in the veneering porcelain compared to SM0.5. Regarding stresses in the zirconia framework, all models had comparable results in maximum principal tensile stresses, except SMW had a lower value. Maximum principal stress levels were located in the veneer component of SM0.3, SM0.5, and SMW, whereas, such levels were observed in the cervical areas of the zirconia frameworks of SMC and control. The SM0.3 had the highest maximum shear stress levels at the zirconia-veneer interface, while SMW had the lowest shear values. The 3D-FEA models with different FDP designs showed different minimum safety factor levels. Conclusions Framework and veneer designs play a significant role in the stress distribution of the partially veneered zirconia FDPs under loading. The FDPs with zirconia frameworks with cap design minimize the maximum principal tensile stress in the veneering porcelain. The FDPs with 0.3-mm-veneering porcelain show low maximum principal tensile stress in the veneering porcelain, but highest maximum shear stress at the zirconia-veneer interface. The FDPs with wave design of zirconia frameworks minimize the maximum shear stress considerably.

Purpose: The aim of this study was to describe different designs of semimonolithic crowns made of translucent and high-translucent zirconia materials and to evaluate the effect on fracture resistance and fracture mode. Methods: One hundred crowns with different designs were produced and divided into five groups (n=20): monolithic (M), partially veneered monolithic (semimonolithic) with 0.3 mm buccal veneer (SM0.3), semimonolithic with 0.5 mm buccal veneer (SM0.5), semimonolithic with 0.5 mm buccal veneer supported by wave design (SMW), and semimonolithic with 0.5 mm buccal veneer supported by occlusal cap design (SMC). Each group was divided into two subgroups (n=10) according to the materials used, translucent and high-translucent zirconia. All crowns underwent artificial aging before loading until fracture. Fracture mode analysis was performed. Fracture loads and fracture modes were analyzed using two-way ANOVA and Fisher’s exact probability tests (P≤0.05). Results: SM0.3 design showed highest fracture loads with no significant difference compared to M and SMW designs (P>0.05). SM0.5 design showed lower fracture loads compared to SMW and SWC designs. Crowns made of translucent zirconia showed higher fracture loads compared to those made of high-translucent zirconia. M, SM0.3, and all but one of the SMC crowns showed complete fractures with significant differences in fracture mode compared to SMW and SM0.5 crowns with cohesive veneer fractures (P≤0.05). Conclusion: Translucent and high-translucent zirconia crowns might be used in combination with 0.3 mm microcoating porcelain layer with semimonolithic design to enhance the esthetic properties of restorations without significantly decreasing fracture resistance of the crowns. If 0.5 mm porcelain layer is needed for a semimonolithic crown, wave design or cap design might be used to increase fracture resistance. In both cases, fracture resistance gained is likely to be clinically sufficient as the registered fracture loads were high in relation to expected loads under clinical use.

Abstract Objective: To evaluate fracture strength of veneered translucent zirconium dioxide crowns designed with different porcelain layer thicknesses. Materials and Methods: Sixty crowns, divided into six groups of 10, were used in this study. Groups were divided according to different thicknesses of porcelain veneer on translucent zirconium dioxide cores of equal thickness (0.5 mm). Porcelain thicknesses were 2.5, 2.0, 1.0, 0.8, 0.5 and 0.3 mm. Crowns were artificially aged before loaded to fracture. Determination of fracture mode was performed using light microscope. Results: Group 1.0 mm showed significantly (p ≤ .05) highest fracture loads (mean 1540 N) in comparison with groups 2.5, 2.0 and 0.3 mm (mean 851, 910 and 1202 N). There was no significant difference (p>.05) in fracture loads among groups 1.0, 0.8 and 0.5 mm (mean 1540, 1313 and 1286 N). There were significantly (p ≤ .05) more complete fractures in group 0.3 mm compared to all other groups which presented mainly cohesive fractures. Conclusions: Translucent zirconium dioxide crowns can be veneered with minimal thickness layer of 0.5 mm porcelain without showing significantly reduced fracture strength compared to traditionally veneered (1.0–2.0 mm) crowns. Fracture strength of micro-veneered crowns with a layer of porcelain (0.3 mm) is lower than that of traditionally veneered crowns but still within range of what may be considered clinically sufficient. Porcelain layers of 2.0 mm or thicker should be used where expected loads are low only.

Aim> To investigate the load-bearing capacity and failure mode of monolithic zirconia fixed dental prostheses (FDPs) fabricated with different connector designs and embrasure shaping methods. Materials and methods> Seventy 4-unit zirconia FDPs (with 2 premolar pontics) were fabricated and divided into 7 groups (n = 10) according to the different connector designs gained by using different embrasure shaping methods. The groups were as follows: monolithic FDPs fabricated with sharp embrasures, monolithic FDPs fabricated with blunt embrasures, monolithic FDPs fabricated with blunt embrasures and no occlusal embrasures, 2 groups of monolithic FDPs fabricated with blunt embrasures and interproximal separations made with diamond discs at the soft stage and at the fully sintered stage, and monolithic FDPs fabricated with blunt embrasures and interproximal separation accentuated by localized porcelain build-up. A final group of fully veneered traditional zirconia FDPs to be used as a control group were fabricated with default milling settings. The FDPs were artificially aged and loaded to fracture. Load to fracture and failure modes were analyzed by 1-way ANOVA, Tukey post-hoc test, and Fisher exact test (α = 0.05). Results> The FDPs fabricated with interproximal porcelain separation showed significantly the highest load to fracture (1038 N ± 82) of all groups (p < 0.001), with no significant difference compared to the FDPs with no occlusal embrasures (934 N ± 175) (p ˃ 0.29). The FDPs fabricated with blunt embrasures showed significantly higher load to fracture (873 N ± 115) compared to the FDPs in control group (689 N ± 75) and the FDPs with sharp embrasures (417 N ± 87) (p < 0.001). There were no significant differences between the FDPs with sharp embrasures (417 N ± 87) and the FDPs with interproximal discs separations (467 N ± 94; p ˃ 0.23). Failure mode of the FDPs fabricated with sharp embrasures and interproximal discs separations differed significantly compared to the FDPs in the other groups (p < 0.001). Conclusions> Sharp embrasures and interproximal separations made with diamond discs significantly decrease the load-bearing capacity of monolithic zirconia FDPs compared to FDPs made with blunt embrasures. Blunt embrasures in combination with localized porcelain build-up produce FDPs with high load-bearing capacity in relation to loads that might be expected under clinical use. This article is protected by copyright. All rights reserved.

Objective: The objective of this study was to compare dental student’s real/practical results at an Objective Structured Clinical Examination (OSCE) with their self-assessed results. These results were compared depending on gender. Introduction: There are several studies published comparing differences in self-assessment between women and men in theoretical exams. However, knowledge is lacking in regards to clinical examinations. At theoretical examinations, it has been found that men tend to over-estimate their performance more frequently than women do. Whether these differences in self-assessment exist because men tend to over-estimate themselves, women tend to under-estimate themselves, a combination of both or that self-assessments actually are consistent with the results at the examination, vary between different studies. Materials and methods: All students (35 women and 16 men) at the sixth semester at Malmö Dental School were examined with an OSCE with 13 stations. The student’s real results at OSCE were compared with their self-assessment at each station. The assessments were compared regarding gender. Results: At most of the 13 stations there were no significant differences in over- and under-estimation regarding women and men. It was more difficult for men to assess their performance regarding impression with alginate. These misjudgments were mainly caused by over-estimation. There were no results indicating that women under-estimate their performance at greater extent than men. Conclusion: Contrary to studies where gender differences concerning self-assessment in theoretical examinations are observed, the present study found no significant differences in over- and under-estimation between women and men.

The aim of this study was to compare porcelain-veneered implant-supported FDPs based on zirconium dioxide and titanium respectively. Sixteen patients received 18 implant-supported partial fixed dental prostheses (FDPs); 8 titanium-based and 10 zirconia-based. The FDPs were randomized between the two material groups. Follow-up of the patients was performed at 3 months and thereafter once a year. An assessment protocol based on the California Dental Association (CDA) quality assessment system was used. Results: All patients were seen at follow-up. The mean time of clinical service at follow-up was 15,2 months (range 12-24 months). All restorations were in place and all patients were satisfied with the treatment. No technical complications were noted in either group. Minor biological complications, in the form of plaque and/or mucositis, not affecting the survival of the restorations were noted for six of the titanium-based restorations and two of the zirconia-based restorations. The difference between the two material groups was not statistically significant. The outcomes of both materials were comparable. Short term data from this study suggests that porcelain-veneered implant-supported partial FDPs based on zirconia and titanium are satisfactory and equal treatment options. This conclusion is however preliminary as it is based on a small number of patients and short-term follow-up. Long-term follow-up of larger groups of patients is needed before more definite conclusions can be made.

OBJECTIVE: To assess the outcomes of implant-supported full-arch fixed dental prostheses (ISFAFDPs) and the supporting implants.

MATERIAL AND METHODS: This retrospective study included patients treated with ISFAFDPs at one specialist clinic. Implant/prosthesis failure and complications were the outcomes analyzed. Survival analysis methods were used.

RESULTS: A total of 709 patients with 869 ISFAFDPs (4,797 implants) were included, with a mean ± SD follow-up of 10.7 ± 7.2 years. A total of 353 implants and 62 prostheses failed. Estimated cumulative survival rates were as follows: 93.3% (95% CI 91.3, 95.3) after 10 years and 87.1% (95% CI 83.4, 90.8) after 20 years. Implants installed in bruxers, smokers, and maxilla had a lower survival than implants installed in non-bruxers, non-smokers, and mandible, respectively. A total of 415 ISFAFDPs (47.8%) presented technical complications, of which 67 (7.7%) presented only occurrences of loss/fracture of implant access hole sealing. Bruxism was a factor to exert a higher risk of screw loosening (HR 3.302; also in younger patients), screw fracture (HR 4.956), ceramic chipping/fracture (HR 5.685), and loss/fracture of acrylic teeth (HR 2.125; this last complication with higher risk also in men, in maxillae, and when the opposing jaw presented natural dentition or fixed prostheses). Patients with bruxism had a statistically significant higher risk of prosthesis failure than non-bruxers (HR 3.276).

CONCLUSIONS: ISFAFDPs presented good long-term prognosis. Failure of several supporting implants was the main reason for failure. The results of the present study strongly suggest that bruxism is an important contributor to implant and prosthesis failure, as well as to an increased prevalence of technical complications in ISFAFDPs.

The aim of this study was to compare the clinical outcomes of implant-supported overdentures (ODs) with either bar-clip or ball attachments. The implant, prosthesis failure, and technical complications were the outcomes analyzed in this retrospective clinical study conducted in a specialty clinic. Seventy-five patients with 242 implants supported by 76 ODs (36 maxillary, 40 mandibular) were included in the study and followed up for 88.8 ± 82.9 months (mean ± standard deviation). Bar-clip and ball attachments were used in 78.9% and 21.1% of the cases, respectively. Forty-three implant failures (17.8%) in 17 prostheses (17/76; 22.4%) were observed in this study. The average period of implant failure was 43.3 ± 41.0 months, and most of them were maxillary turned implants. The bar-clip system demonstrated more complications in the attachment parts compared to the ball attachment system. Poor retention of the prosthesis was similar between the two systems. Loss of implants resulted in the failure of 10 ODs in this study. ODs opposed by natural dentition or fixed prostheses presented with more complications. The Cox proportional hazards model did not show a significant effect on prosthesis failure for any of the factors. These findings indicated that patients with ODs need constant maintenance follow-ups to address the technical complications and perform prosthodontic maintenance regardless of the attachment system used.

BACKGROUND: The oral rehabilitation with fixed restorations supported by the combination of teeth and dental implants has been advocated in some cases.

PURPOSE: To assess the clinical outcomes of these prostheses. Fixed restorations supported by the combination of teeth and dental implants.

MATERIALS AND METHODS: This retrospective study included all patients treated with combined tooth-implant-supported fixed dental prostheses (FDPs) at one specialist clinic. Abutment/prosthesis failure and technical complications were the outcomes analyzed.

RESULTS: A total of 85 patients with 96 prostheses were included, with a mean follow-up of 10.5 years. Twenty prostheses failed. The estimated cumulative survival rate was 90.7%, 84.8%, 69.9%, and 66.2% at 5, 10, 15, and 20 years, respectively. The failure of tooth and/or implant abutments in key positions affected the survival of the prostheses. There were seven reasons for prostheses failure, with the loss of abutments exerting a significant influence. Bruxism was possibly associated with failures. Prostheses with cantilevers did not show a statistically significant higher failure rate. No group had a general higher prevalence of technical complications in comparison to the other groups.

CONCLUSIONS: Although combined tooth-implant-supported FDPs are an alternative treatment option, this study has found that across 20 years of service nearly 35% the prostheses may fail.

BACKGROUND: Implant-supported fixed partial dentures (ISFPDs) are one of the most common options to rehabilitate partially edentulous patients.

PURPOSE: To assess the clinical outcomes of ISFPDs.

METHODS: This retrospective study included all patients treated with ISFPDs with 2 to 6 prosthetic units at one specialist clinic. Implant/prosthesis failure and technical complications were the outcomes analyzed.

RESULTS: Six hundred and forty-two patients with 876 ISFPDs (2241 implants) were included, followed up for 108.0 ± 76.2 months. Eighty-eight prostheses and 112 implants (26 before, 86 after prosthesis installation) failed. The estimated CSR of ISFPDs at 30 years was 72.7%. Smokers presented lower implant survival than nonsmokers. Two hundred and ninety-nine ISFPDs (33.2%) presented technical complications. Bruxism was a factor to exert a higher risk of screw and implant fracture, and ceramic chipping. ISFPDs with cantilever presented higher risk of failure, and screw loosening/fracture. Prostheses supported by implants with internal abutment connection or with two pontics had higher risk of presenting ceramic chipping. Extension of the prosthesis did not seem to exert influence on prosthesis failure/complications.

CONCLUSIONS: ISFPDs presented good long-term prognosis. Implant failure was the main reason for ISFPD failure. The results suggest that bruxism and the presence of cantilever may contribute to the increased rate of mechanical complications and prosthesis failure.

Objective: To retrospectively assess the clinical outcomes of implant‐supported single crowns and the supporting implants. Material and Methods: This retrospective study included all patients treated with implant‐supported single crowns at one specialist clinic. Implant and prosthesis failure, and mechanical/technical complications (ceramic fracture/chipping; crown loss of retention/mobility; crown failure/fracture; loosening/loss/fracture of prosthetic screw; implant failure/fracture) were the outcomes analyzed. Any condition/situation that led to the removal/replacement of crowns was considered prosthesis failure. Results: 438 patients with 567 crowns were included. Mean±SD follow‐up of 183.4±69.3 months. 37 implants (6.5%) and 54 crowns (9.5%) failed. If only technical problems were considered, the crown failure rate decreased to 4.1% (23/567). Most common reasons for crown failure: esthetic issue (n=12), crown constantly mobile (n=9), change to another type of prosthesis together with other implants (n=8), crown fracture (n=7), crown in infraposition in comparison to adjacent teeth (n=7). The odds of crown failure were shown to be statistically significantly higher for the following factors: younger patients, maxillary crowns, and screw‐retained crowns. Loose prosthetic screw was much more prevalent in screw‐retained than in cemented crowns. Ceramic fracture/chipping was more prevalent in screw‐retained crowns, maxillae, females. Crown fracture was more prevalent in ceramic crowns, screw‐retained crowns, maxillae, posterior region, females. However, these differences were statistically significant only for crown fractures in females. Conclusions: The odds of crown failure were significant for some factors, but one must keep in mind that non‐technical complications are as common as technical ones as reasons for the replacement of implant‐supported single crowns.

(1) Background: This paper aimed to compare the cleanliness of clinically well-documented implant systems with implants providing very similar designs. The hypothesis was that three well-established implant systems from Dentsply Implants, Straumann, and Nobel Biocare were not only produced with a higher level of surface cleanliness but also provided significantly more comprehensive published clinical documentation than their correspondent look-alike implants from Cumdente, Bioconcept, and Biodenta, which show similar geometry and surface structure. (2) Methods: Implants were analyzed using SEM imaging and energy-dispersive X-ray spectroscopy to determine the elemental composition of potential impurities. A search for clinical trials was carried out in the PubMed database and by reaching out to the corresponding manufacturer. (3) Results: In comparison to their corresponding look-alikes, all implants of the original manufacturers showed-within the scope of this analysis-a surface free of foreign materials and reliable clinical documentation, while the SEM analysis revealed significant impurities on all look-alike implants such as organic residues and unintended metal particles of iron or aluminum. Other than case reports, the look-alike implant manufacturers provided no reports of clinical documentation. (4) Conclusions: In contrast to the original implants of market-leading manufacturers, the analyzed look-alike implants showed significant impurities, underlining the need for periodic reviews of sterile packaged medical devices and their clinical documentation.

Purpose: After some initial setbacks in the 1970s, ceramic implants seem to be a promising alternative to titanium implants. Since the surface of an implant system represents the interface to surrounding biologic structures, the study focuses on cleanliness and surface topography. Clinical documentation of the corresponding systems completes the picture and allows a better evaluation of zirconia implant systems. Materials and Methods: Five different ceramic implant systems were selected randomly and purchased via blind-shopping: Z5s (Z-Systems), ZiBone (COHO), W implant (TAVDental), ceramic. implant (vitaclinical), and BioWin!/Standard Zirkon Implantat (Champions-Implants/ZV3 system). Three samples of each implant system underwent scanning electron microscopy (SEM) imaging and elemental analysis (EDS). Where appropriate, subsequent Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was performed to identify the chemical nature of impurities. Surface topography was evaluated, and a search for clinical trials in the PubMed database, on the websites and by written request to each dental implant manufacturer, was performed. Results: Surfaces of Champions implants (ZV3) and Z-Systems implants were relatively clean, whereas the other investigated surfaces of vitaclinical, TAV Dental, and ZiBone implants all displayed organic contaminations on their surfaces. Four of the investigated ceramic implants showed a moderately rough implant surface. Only the vitaclinical ceramic.implant had minimal surface roughness. Three ceramic designs—vitaclinical, ZV3, and Z-Systems—had clinical trials documented with up to 3 years of follow-up and results varying between 82.5% and 100% survival. TAV Dental W and ZiBone implant systems lacked properly conducted clinical recording of results. Conclusion: The results of this study showed that it is technically possible to produce zirconia implants that are largely residue-free. On the other hand, the variety of significant residues found in this analysis raises concerns, as contamination may lead to undesirable biologic effects. The lack of clinical studies in peer-reviewed journals does not seem to be relevant for the approval of marketing, nor does the lack of surface cleanliness. In the authors’ opinion, a critical analysis of these aspects should be included in a more stringent future analysis prior to the marketing of oral implant systems.

Purpose: To systematically evaluate and compare the clinical performance of lithium disilicate (LDS)and zirconium dioxide (ZrO2)-based ceramic monolithic crowns in the posterior dentition. Materials and Methods: Treatment was administered by two experienced general dental practitioners in two public dental health care clinics. Forty-four patients received 60 crowns randomized to be either LDS or ZrO2 and cemented with resin cement. Evaluations were performed after 3 years using California Dental Association criteria. Results: The mean follow-up time was 40 months (range: 31 to 50). No crown fractured during the observation time, and no chip-off fractures occurred. The success rate for ZrO2 was 80%, and the survival rate was 93.3%. For LDS, the success rate was 89.7%, and the survival rate was 100%. Survival after 3 years for all crowns together was 96.6%, and success was 84.7%. There was no significant difference between the two materials. Conclusion: Crowns made of monolithic translucent ZrO2 and LDS show equal and promising clinical results from a short-term perspective. There seems to be a difference between how patients and professionals rate crowns concerning esthetics (color and shape), with patients rating the restorations more favorably.

Purpose: To assess the clinical outcomes of maxillary overdentures supported by dental implants by conducting a literature review. Materials and Methods: An electronic search was undertaken in March 2019. Eligibility criteria included publications reporting cases of implant-supported maxillary overdentures with follow-up information. Results: A total of 131 publications were included (1,478 overdentures supported by 6,681 implants). The mean number of attachments per overdenture was 3.8 ± 1.2 (range: 1 to 9), and a bar-clip system was used in about half of the cases. The prostheses were followed up for a mean of 47.9 ± 32.8 (range: 1 to 240) months. A total of 401 implants (6.0%) failed in 219 patients (14.8%), and 55 prostheses (3.7%) failed at a mean of 40.2 ± 53.2 (range: 6 to 240) months after placement. Most of the failures happened within the first year after placement for both implants (52.1%) and prostheses (41.8%). Patients with fewer implants per prosthesis presented higher prosthesis failure rates than patients with more implants per prosthesis. The cumulative survival rate for dental implants after 19 years was 70.4%, and for implant-supported maxillary overdentures was 79.8%. Presence of palatal coverage and/or metallic structure/reinforcement does not seem to have an influence on failure rate. Of the most commonly used attachment systems, the ball/O-ring and the Ceka were the ones with the highest rates of patients having at least one implant failure. Conclusion: Most of the prosthesis failures were due to loss of implants, and the first year was the most critical period for failures. The number of dental implants placed per patient seemed to have an impact on the occurrence of overdenture failure.

Objectives/aim To analyze and compare costs of different prosthetic rehabilitations for the edentulous maxilla. Materials and methods Patients with edentulous maxillae were rehabilitated with either of three implant-supported prosthetic protocols; removable overdenture supported by 2 implants (ISOD 2), fixed dental prostheses supported by 4 (ISFAFDP 4) or 6 (ISFAFDP 6) implants. Cost of treatment and costs during follow-up were registered and compared. Results Twenty-four patients were included: six patients received ISOD 2 treatment, eight patients received ISFADP 4 treatment and ten patients received ISFADP 6 treatment. Initial costs for ISFAFDP 6 were higher than costs for ISFAFDP 4 and ISOD 2, but there were no differences in cost for maintenance i.e., the ISOD treatment remained the least costly treatment alternative after 1-year follow-up. Discussion The lack of difference in cost for maintenance and repair over the first year suggests that implant-supported overdentures will remain the least costly treatment option for the edentulous maxilla, at least in a short-term perspective. Conclusions Removable maxillary overdentures supported by 2 implants may be a valid low cost treatment option.

The purpose of the study was to investigate the influence of multiple factors on the survival of tooth-supported single crowns and assess the biological and technical complications. This retrospective study included patients rehabilitated with single crowns with a minimum follow-up time of 6 months after delivery. The cumulative survival rate was calculated over the maximum period of follow-up time and reported in a life-table survival analysis. Univariate and multivariate Cox regression was used to evaluate the associations between clinical covariates and crown failure. The included cohort group consisted of 1037 single crowns delivered in 401 patients and followed for a mean of 134.8 ± 80.2 months. Cumulative survival rate was 89.9% and 80.9% after 5 and 10 years and 70.5% and 61.8% after 15 and 20 years, respectively. The main reasons for single crown failure were loss of retention, tooth loss, and fracture. Anterior placement, non-vital abutments, and bruxism significantly influenced the survival of single crowns. The survival of single crowns was not influenced by patient's age and sex, location of the crowns in relation to the jaws, type of tooth, presence of post and core, and type of crown material, treatment providers, or smoking. Anterior placement, non-vital abutments, and bruxism are factors suggested to increase the risk of single crown failure and the prevalence of technical and biological complications.

Background: Tooth-supported fixed dental prosthesis (FDP) is one of the most reliable treatment options to replace missing teeth. The longevity of the treatment could, however, be affected by several general and local factors, especially bruxism.

Objective: To investigate the influence of bruxism on the long-term survival of tooth-supported FDPs in bruxers compared to a matched group of nonbruxers, taking several clinical variables into account.

Materials and methods: The present retrospective cohort study was based on records of patients treated with 3-7-unit tooth-supported FDPs with a minimum follow-up time of 6 months after prosthesis delivery. The criteria for the diagnosis of "possible" and "probable" sleep or awake bruxism were used. A matched group of nonbruxers was selected on the basis of similarities in four factors, patients' gender and age, number of prosthetic units of the FDPs, and follow-up time. The paired-samples t-test or Wilcoxon signed rank test were used to compared mean values between the two groups. Contingency tables of categorical data were analyzed by McNemar's test.

Results: The cohort group consisted of 62 noncantilevered FDPs in each group, followed up for a mean of 110.1 and 106.5 months (bruxers and nonbruxers, respectively). Tooth-supported FDPs in bruxers presented significantly higher failure rate than in nonbruxers (32.3% vs. 25.8%, respectively; p = 0.001). Loss of retention and tooth loss were the main reasons for failures in both groups. For nonsmokers, the FDP failure rate was higher in nonbruxers. Technical and biological complications were significantly more prevalent in bruxers compared to nonbruxers.

Conclusions: Bruxism is suggested to increase technical and biological complications and FDP failure.

PURPOSE: To assess the influence of several factors on the survival of tooth-supported fixed partial dentures (FPDs) with vital and non-vital abutments.

MATERIALS AND METHODS: The present retrospective cohort study was based on the records of patients treated with 3-to-7-unit tooth-supported FPDs with a minimum follow-up time of 6 months after prosthesis delivery. Cumulative survival rate (CSR) was calculated over the maximum follow-up period. Cox regression models were used to evaluate the association between the clinical covariates and prosthesis failure.

RESULTS: A total of 331 FPDs in 229 patients were included. The CSRs were 90.1% and 77.6% after 5 and 10 years and 67.9% and 52.1% after 15 and 20 years, respectively. Tooth-supported FPD failure was more prevalent within the first years of prosthesis delivery. Loss of one or more abutment teeth and loss of prosthesis retention were the main reasons for failure. Smoking and type of prosthesis material significantly influenced the survival of FPDs. Abutment vitality, position of the non-vital abutment, or prosthesis length did not show any significant influence on the occurrence of prosthesis failure.

CONCLUSION: Smoking and the type of prosthesis material are suggested to contribute to an increased rate of FPD failure irrespective of abutment vitality.

PURPOSE: To evaluate the survival rate of full-coverage tooth-supported fixed prosthetic restorations, single crowns (SCs), and fixed dental prostheses (FDPs), taking into consideration the potential influence of tooth-vitality, presence and type of post, and type of prosthetic restoration material.

MATERIALS AND METHODS: In October 2022, two authors independently conducted a search in PubMed, Web of Science, and Scopus electronic databases as well as a hand search to identify clinical human studies on full-coverage SCs and FDPs supported by vital and/or non-vital abutments and/or a combination of both, with a minimum observation period of 24 months.

RESULTS: Out of 4198 studies identified through the database search and 22 through hand searching, 26 studies fulfilled the inclusion criteria and were included in the analysis of the present systematic review. Included studies scored six points and more according to Newcastle-Ottawa Scale (NOS). The highest estimated 5-year survival rate was observed for (metal-ceramic and all-ceramic) SCs on vital teeth (98.3%; 95% CI [98.1, 98.6%]) and all ceramic SCs on non-vital teeth with fiber post (95.0%; 95% CI [94.5-95.4%]). Metal-ceramic SCs on vital teeth (97.1%; 95% CI [95.6-98.7%]) showed a statistically significant higher estimated 5-year survival rate compared to metal-ceramic SCs with cast metal post (90.7%; 95% CI [87.4-94.0%], P < 0.001), fiber post (91.3%; 95% CI [90.9-91.6%], P < 0.001) and without post (85.7%; 95% CI [80.7, 90.6%], P < 0.032). All-ceramic SCs with fiber post had a statistically significant higher estimated 5-year survival rate (95.0%; 95% CI [94.5-95.4%]) compared to metal-ceramic SCs on non-vital teeth with fiber post (91.3%; 95% CI [90.9-91.6%], P < 0.001). SCs (all-ceramic and metal-ceramic) with fiber post had a statistically significantly higher estimated 5-year survival rate of (92.7%; 95% CI [92.4-92.9%]) than SCs made of metal-ceramic and retained by cast metal post (90.7%; 95% CI [87.4-94.0%], P < 0.001). For FDPs, the 5-year survival rate was significantly higher for FDPs on vital abutments (84.9%; 95% CI [75.9, 93.9%]) compared to FDPs retained by non-vital abutment/s (81.3%; 95% CI [80.3, 82.2%], P = 0.049) irrespective to presence, type of post, and FDPs material. The results are limited by the limited number of studies and the presence of uncontrolled confounding clinical variables.

CONCLUSIONS: Within the limitations of the study, tooth vitality is suggested to contribute positively to the survival of SCs and FDPs.

AIM: To compare the amount of remaining cement excess after cementation of implant-supported zirconia crowns with zinc phosphate or calcium aluminate glass ionomer cement.

MATERIALS AND METHODS: Twenty zirconia crowns were cemented on dental implant abutments using a calcium aluminate glass ionomer cement (n = 10) and zinc phosphate cement (n = 10). After removal of cement excess, remaining cement excess were measured with pixel area calculation method and by weighing. Differences in amount of remaining cement excess were analyzed using Independent Samples t-Test. Level of significance was set at p = 0.05.

RESULTS: Zinc phosphate cement had a significantly greater amount of remaining cement excess than calcium aluminate glass ionomer cement in terms of total number of pixels (p = 0.002) and amount in grams (p = 0.005).

CONCLUSION: The study suggests that the amount of remaining cement excess can be affected by the type of cement. Calcium aluminate glass ionomer cement may be a more suitable choice for cement-retained dental implant restorations, and possibly reduce the risk of complications related to cement excess such as peri-implant disease. Further studies are needed to verify the results from the present study.

Purpose: To investigate the impact of different extents of misfit between a restoration and the supporting implant on veneer fractures in screw-retained implant-supported metal-ceramic fixed dental prostheses (FDPs). Materials and Methods: A finite element analysis (FEA) model of a five-unit screw-retained metal- ceramic FDP supported by three implants was constructed, replicating a previous in vitro study. Eight different gap configurations at the single terminal implant, ranging from 0 to 150 μm, were tested. All setups were tested after clamping and with a load of 200 N applied. Maximum stress within the FDP was calculated. Results: The stress increased with each increase in misfit size above 30 μm, with the relationship between gap size and stress being linear up to 100-μm misfit. Above 100 μm, the stress increase accelerated. The stress pattern within the FDP changed with increasing gap size, confirming the findings of a previously conducted in vitro experiment for a misfit of 150 μm. Conclusion: The results of the FEA were in agreement with in vitro observations, validating the predictive value of FEA for technical complications. A misfit between an FDP and a supporting implant implies an increased risk of veneer fracture. Above a misfit of 30 μm, the stress levels are likely to be high enough to cause veneer fracture, and the risk increases disproportionately for misfit above 100 μm.

Because new zirconia materials are constantly being developed, the aim was to identify and qualitatively synthesize research on how processing and time-related factors affect the properties of high translucent (HT) zirconia intended for monolithic restorations. Cochrane Library, PubMed, Scopus, Web of Science, and reference lists were searched for in vitro and clinical studies. Eligibility and risk of bias were assessed. A synthesis of 142 publications was performed. HT 3Y-TZP was the most common, followed by 5YSZ, 4YSZ, and multilayer. In the laboratory, HT 3Y-TZP should be sintered according to the manufacturer’s recommendation and polished before glazing to favour strength, roughness, and wear behaviour. In the clinic, polishing is necessary after grinding to favour roughness and aging resistance. Over time, when using hydrothermal aging, t–m phase transformation and reduced translucency are expected, without affecting the strength and roughness. The strength of 4YSZ and 5YSZ is unaffected. However, the time-related methods are of questionable clinical significance. The evidence of all other factors’ effects on the properties of HT zirconia is lacking or limited; thus, these factors are of relevance for future research. There is a high heterogeneity of study designs and methods, and the results are brand-dependent.

Abstract Objective. The aim of the study was to provide data on the fracture strength of monolithic high translucent Y-TZP crowns and porcelain-veneered high translucent Y-TZP crown cores and to compare that data with the fracture strength of porcelain-veneered Y-TZP crown cores and monolithic lithium disilicate glass-ceramic crowns. Materials and methods. Sixty standardized crowns divided into six groups (n = 10) were fabricated: monolithic high translucent Y-TZP crowns, brand A, monolithic high translucent Y-TZP crowns, brand B, veneered high translucent Y-TZP crown cores, brand A, veneered high translucent Y-TZP crown cores, brand B, heat-pressed monolithic lithium disilicate crowns and veneered Y-TZP crown cores. All crowns were thermocycled, cemented onto dies, cyclically pre-loaded and finally loaded to fracture. Results. The monolithic Y-TZP groups showed significantly higher fracture strength (2795 N and 3038 N) compared to all other groups. The fracture strength in the veneered Y-TZP group (2229 N) was significantly higher than the monolithic lithium disilicate group (1856 N) and the veneered high translucent Y-TZP groups (1480 N and 1808 N). Conclusions. The fracture strength of monolithic high translucent Y-TZP crowns is considerably higher than that of porcelain-veneered Y-TZP crown cores, porcelain-veneered high translucent Y-TZP crown cores and monolithic lithium disilicate crowns. The fracture strength of a crown made of monolithic high translucent Y-TZP is, with a large safety margin, sufficient for clinical use for the majority of patients. Porcelain-veneered Y-TZP crown cores show higher fracture resistance than monolithic lithium disilicate crowns.

AIM: To describe the implementation of a digital tool for preparation validation and evaluate it as an aid in students' self-assessment. METHODS: Students at the final semester of skills laboratory training were asked to use a digital preparation validation tool (PVT) when performing two different tasks; preparation of crowns for teeth 11 and 21. The students were divided into two groups. Group A self-assessed and scanned all three attempts at 21 ("prep-and-scan"). Group B self-assessed all attempts chose the best one and scanned it ("best-of-three"). The situation was reversed for 11. The students assessed five parameters of the preparation and marked them as approved (A) or failed (F). These marks were compared with the information from the PVT. The students also completed a questionnaire. Each question was rated from 1 to 5. Teachers' opinions were collected at staff meetings throughout the project. RESULTS: Most students in the "prep-and-scan" groups showed an increase in agreement between their self-assessment and the information from the PVT, whereas students in the "best-of-three" groups showed lower levels of agreement. All students rated the PVT positively. Most strongly agreed that the tool was helpful in developing skills (mean 4.15), easy to use (mean 4.23) and that it added benefits in comparison to existing assessment tools (mean 4.05). They did not however, fully agree that the tool is time efficient (mean 2.55), and they did not consider it a substitute for verbal teacher feedback. Teachers' feedback suggested advantages of the tool in the form of ease of use, visual aid and increasing interest and motivation during skills laboratory training however, they did not notice a reduction in need of verbal feedback. CONCLUSIONS: Within the limitations of the study, our conclusion is that a digital PVT may be a valuable adjunct to other assessment tools in skills laboratory training.

Aim: Self-assessment ability is a crucial skill for any professional. Training self-assessment leads to improved capabilities and should be performed continuously during the dental education. Using different tools for self-assessment creates variation and improves motivation to continue training. The aim of the present study was to implement a newly developed tool for preparation validation in skills lab training and evaluate students’ as well as teachers’ experiences using a questionnaire. Materials and Methods: The Faculty of Odontology in Malmö works with a problem based approach towards learning and strongly encourages self-assessment in the learning situation. The Prep Validation program from the KaVo Dental Teacher system is a newly introduced program with multiple applications – one being the possibility to be used for self-assessment. When students do skills lab training they can use the instrument to scan their own preparation and then compare it to the unprepared tooth as well as the teacher´s master preparation. The visual image provides an immediate feedback which is easy to interpret. Students can assess their preparation in comparison with the master preparation and make adjustments accordingly. The program was used for two different preparation types in the prosthetic rehabilitation skills lab training of dental students (n=59). They were asked to answer a questionnaire afterwards. The questionnaire consisted of four questions concerning whether the tool helped in developing skills, whether it reduced time to reach the required standard of preparation, whether it was easy to use and if it provided added benefits in comparison to existing self-assessment tools (forms used for self- and peer-assessment) and teacher feedback respectively. Results: The results are currently being processed. Preliminary interpretation suggests that students’ experiences are divided where some consider the Prep Validation program a valuable tool and others do not. The first group appreciates the immediate visual feedback, easy unbiased interpretation and considers the tool to be simple to use, reduce the total time needed for them to reach the required standard of preparation and reduce the need for teacher feedback. The other group of students does not regard the tool to provide added benefits in comparison to existing self-assessment tools and teacher feedback. Conclusions: A preliminary conclusion is that some students appreciate the visual aids of the program whereas others manage well without it. Different students favor different tools to use for self-assessment to help their skills lab training.

ABSTRACTThe loss of teeth can affect a person’s appearance and functions such as eating and speaking. There is thus a need for prosthetic re-habilitation to improve quality of life. For many patients, a fixed dental restoration is preferred, and a common restoration is a por-celain-fused-to-metal bridge retained by teeth or implants. Metal-based restorations can potentially cause adverse reactions though, and this is indication for the search for alternative materials. All-ceramic materials are characterized by strong atomic bonds that make them reluctant to react with the environment, and thus unlikely to cause adverse reactions. All-ceramic materials have other attractive material properties and excellent aesthetic proper-ties and have been successfully used in dentistry, mostly for smaller anterior restorations. Ceramics do not withstand tensile forces as well as metals though, and are susceptible to brittle fractures. The connector area is especially prone to fracture.During later years, a new type of ceramic material, based on zir-conium dioxide, has been developed. Yttria-stabilized tetragonal zirconia polycrystals, Y-TZP, has a unique ability to resist crack propagation by being able to transform from one crystalline phase to another, and the resultant volume increase stops the crack and inhibits it from propagating. This material has the potential to be used for larger restorations and in the molar area. Not enough in-formation, however, is available on clinical follow-up of zirconia-based restorations, especially long-term, and information on all-ceramic restorations supported by implants is lacking.The over-all aim of this thesis was to evaluate how to design zir-conia-based restorations to achieve increased fracture resistance and evaluate the clinical performance of implant-supported zirco-nia-based restorations.In paper I implant-supported all-ceramic fixed partial dentures of two different ceramic materials were compared; a zirconia-toughened alumina material (group 1) and a densely sintered Y-TZP material (group 2). Eighteen patients were randomly divided between the two groups. At the one-year follow-up, all restorations were in function and no complete fractures were noted. Fractures of the veneering material were noted, however. There was a signifi-cant difference between the two materials; 54% of the restorations in group 2 showed veneer fractures compared to 8% of the restora-tions in group 1. Paper IV is a five-year follow-up of the same patient groups. All restorations were still in function without complete fractures, but an increase in veneer fractures was noted; 69% of the restorations in group 2 showed veneer fractures compared to 17% in group 1.In paper II the fracture strength was evaluated for 4-unit Y-TZP fixed dental prostheses frameworks with different connector di-mensions; 2.0, 2.5, 3.0, 3.5 and 4.0 mm. The results showed a sig-nificant increase in load at fracture for each increase in connector diameter and recommendations for clinically relevant connector dimensions were suggested. In paper III implant-supported Y-TZP fixed full-arch mandibular dentures were evaluated. At the three-year follow-up all restora-tions were in function and no complete fractures were noted. Frac-tures of the veneering material were however noted in nine of the ten patients, at 34% of the units. In paper V the fracture strength of crowns with different types of Y-TZP core materials and different core design and veneering ma-terials was evaluated. The crowns were cemented onto tooth-like abutments, except for one group cemented onto implant-like tita-nium abutments. The results showed significantly higher loads at fracture and different fracture mode for crowns with anatomically shaped cores compared to simple cores with even thickness. Crowns supported by implant-like titanium abutments showed sig-nificantly higher loads at fracture than did those supported by tooth-like abutments. Type of core-material and veneering material did not influence the results.

Metallfria zirkoniumdioxid-baserade konstruktioner fungerar. Totalfrakturer förekommer inte på implantatstödda konstruktioner, däremot noteras en hög förekomst av frakturer i ytkeramen. Hänsyn till designen av innerkärna/broskelett är mycket betydelsefull för ett bra resultat.

Objective: to compare fracture load and fracture mode of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and metal-ceramic (MC) molar crowns using a modified test set-up to produce fractures similar to those seen in vivo, i.e. fractures of the veneering material rather than complete fractures. Materials and methods: 13 high-noble-alloy MC and 13 Y-TZP molar crowns veneered with porcelain were manufactured. The crowns were artificially aged before final load to fracture. Load was applied using a 7mm diameter steel ball exerting force on the cusps with stresses directed toward the core-veneer interface. Fracture surface analysis was performed using light- and scanning electron microscopy. Results: The test design produced fractures of the veneering material rather than complete fractures. MC crowns withstood significantly (p>.001) higher loads (mean 2155 N) than Y-TZP (mean 1505 N) crowns yet both endure loads sufficient for predictable clinical use. Fracture mode differed between MC and Y-TZP. MC crowns exhibited fractures involving the core-veneer interface but without core exposure. One Y-TZP crown suffered a complete fracture, all others displayed fractures of the veneering material involving the core-veneer interface with core exposure. Conclusions: The test set-up produces fractures similar to those found in vivo and may be useful to evaluate the core-veneer interface of different material systems, both metals and ceramics. The study confirms suggestions from previous studies of a weaker core-veneer bond for Y-TZP compared to MC crowns.

Abstract Objectives: The aim of this study was to evaluate the effect of different types and design of zirconia frameworks as well as the effect of different veneering ceramics on the fracture strength of crowns. The importance of different abutment materials was also evaluated. Materials and methods: Eighty cores, 40 in a fully-sintered zirconia material and 40 in a pre-sintered zirconia material were made. Twenty cores of each material were made with a core of even thickness shape (ES) and 20 were made with a core with anatomical shape (AS). The cores were divided into subgroups and veneered with one of two different veneering ceramics: a porcelain and a glass-ceramic material. In total eight groups of 10 crowns were made. They were all cemented onto abutments made of resin. One extra group of 10 AS, pre-sintered zirconia cores veneered with glass-ceramic were made and cemented onto titanium abutments. All crowns underwent thermocycling and mechanical pre-load and were finally loaded until fracture. Results: AS crowns withstood significantly higher loads than ES crowns (P-value <0.001), and crowns with titanium abutments withstood significantly higher loads than crowns supported by abutments made of inlay pattern resin (P-value <0.001). Three types of fracture were noted: minor and major fracture of the veneering ceramic, and complete fracture through core and veneer. ES crowns showed significantly more major fractures of the veneering ceramic than AS crowns. Conclusions: This in vitro study indicates that the design of the core, as well as the abutment support, significantly influences fracture load and fracture mode of yttria-stabilized tetragonal zirconia polycrystals crowns.

Objectives: The purpose of this study was to evaluate the clinical performance of two- to five-unit implant-supported all-ceramic restorations and to compare the results of two different all-ceramic systems, Denzir® (DZ) and In-Ceram Zirconia® (InZ). Methods: Eighteen patients were treated with a total of 25 two- to five-unit implant-supported fixed dental prostheses. Nine patients were given restorations of the DZ system and the other nine were given restorations of the InZ system. The restorations were cemented with zinc phosphate cement onto customized titanium abutments and were evaluated after one, three and five years. Results: At the five-year follow-up, all restorations were in function; none had fractured. Superficial cohesive (chip-off) fractures were, however, observed in 9 of the 18 patients (11 of 25 restorations). Sixteen units in the DZ group (9 of 13 restorations) and 3 in the InZ group (2 of 12 restorations) had chip-off fractures. The difference between the two groups regarding frequency of chip-off fractures was statistically significant (P<0.05 at FDP level and P<0.001 at unit level). Conclusion: The results suggest that all-ceramic implant-supported fixed dental prostheses of two- to five-units may be considered a treatment alternative. The DZ system as used in this study, however, exhibits an unacceptable amount of veneering porcelain fractures and thus cannot be recommended for the type of treatment evaluated in this trial. Poor compatibility or problems with the bond mechanisms between veneer and framework could not explain the chip-off fractures. Factors concerning veneering porcelain need to be further evaluated.

PURPOSE: The aim of this study was to evaluate the clinical performance of two- to five-unit implant-supported all-ceramic restorations and to compare the results of two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ). MATERIALS AND METHODS: Eighteen patients were treated with a total of 25 two- to five-unit implant-supported fixed dental prostheses. Nine patients were given DZ system restorations and 9 were given InZ system restorations. The restorations were cemented with zinc phosphate cement onto customized titanium abutments and were evaluated after 1, 3, and 5 years. RESULTS: At the 5-year follow-up, all restorations were in function; none had fractured. However, superficial cohesive (chip-off) fractures were observed in 9 of 18 patients (11 of 25 restorations). Sixteen units in the DZ group (9 of 13 restorations) and 3 in the InZ group (2 of 12 restorations) had chip-off fractures. The difference between the two groups regarding frequency of chip-off fractures was statistically significant (P < .05 at the FDP level and P < .001 at the unit level). CONCLUSION: The results suggest that all-ceramic implant-supported fixed dental prostheses of two to five units may be considered a treatment alternative. The DZ system, however, exhibited an unacceptable amount of veneering porcelain fractures and thus cannot be recommended for the type of treatment evaluated in this trial. Poor compatibility or problems with the bond mechanisms between the veneer and framework could not explain the chip-off fractures. Stress distribution, as well as other factors concerning the veneering porcelain, need to be evaluated further.

Objective. The purpose of this pilot study was to evaluate the long-term clinical performance of implant-supported full-arch zirconia-based fixed dental prostheses (FDPs). Materials and methods. Ten patients received full-arch zirconia-based (Cercon) mandibular FDPs supported by four implants (Astra Tech). Nine patients received 10-unit FDPs and one patient received a 9-unit FDP. The FDPs were cemented onto individually prepared titanium abutments and were evaluated at baseline and after 12, 24, 36 and 96 months. Results. Nine patients attended the 8-year follow-up. None of the restorations showed bulk fracture, all FDPs were in use. Fractures of the veneering porcelain were, however, observed in eight patients. A total of 36 out of 89 units (40%) showed such fractures. Patient satisfaction was excellent despite the veneering material fractures. Conclusion. Results from this 8-year pilot study suggest that implant-supported full-arch zirconia-based FDPs can be an acceptable treatment alternative.

PURPOSE: The aim of this study was to evaluate the long-term clinical performance of and patient satisfaction with implant-supported all-ceramic fixed dental prostheses (FDPs) and to compare two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ). MATERIALS AND METHODS: A total of 18 patients received 25 partial FDPs; 13 DZ, and 12 InZ. RESULTS: Of these patients, 17 attended the 10-year follow-up. None of the restorations had fractured. Fractures of the veneering porcelain were observed in nine patients; two from the InZ group and seven from the DZ group. All FDPs were in use, and all patients were fully satisfied with the treatment. CONCLUSION: Results from this long-term follow-up suggest that implant-supported all-ceramic FDPs are an acceptable treatment alternative.

Reported clinical success rates of all-ceramic fixed partial dentures (FPDs) made of high-strength oxide ceramics range between 82.5% and 100%. The main cause of all-ceramic FPD failure is fracture in the connector area. There is, however, no consensus on what connector dimensions are adequate. The aim of this in-vitro study was, therefore, to compare the fracture strength of four-unit Y-TZP FPD cores designed with different connector diameters. A total of 40 four-unit FPD cores supported by end abutments and having two pontics were manufactured in Procera Zirconia. Five groups of FPD cores with connector dimensions of 2.0, 2.5, 3.0, 3.5 and 4.0 mm were produced. All FPD cores underwent a firing programme according to the manufacturer's recommendations for the veneering porcelain, a cyclic preload, thermocycling and finally, load until fracture. Fracture strength was significantly higher for each increase in connector diameter except for the 2.0-mm and 2.5-mm diameters where all fractures occurred during preload. All FPD cores fractured in the connector area. Within the limitations of this in-vitro study, a minimum diameter of 4.0 mm is recommended for all-ceramic zirconia-based FPDs with long spans or replacing molars. Clinical studies are, however, needed to determine adequate connector dimensions.

PURPOSE: The development of high-strength oxide ceramic materials has led to increased interest in all-ceramic fixed dental prostheses (FDPs). Success rates reported in clinical studies for all-ceramic FDPs based on high-strength oxide ceramic materials reportedly approach those of porcelain-fused-to-metal FDPs. These reconstructions, however, are still of limited size and have mainly concerned FDPs supported by natural teeth. The purpose of this study was to evaluate the clinical performance of multiunit all-ceramic FDPs supported by dental implants. MATERIALS AND METHODS: Ten patients received mandibular yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) FDPs manufactured according to the Cercon technique and supported by four Astra Tech implants. Nine patients received 10-unit FDPs and one patient received a 9-unit FDP. The FDPs were cemented with Panavia F 2.0 onto individually prepared titanium abutments. The FDPs were evaluated at baseline and after 12, 24, and 36 months. RESULTS: At the 3-year follow-up, all FDPs were in use, and all patients were fully satisfied with their treatment. None of the reconstructions had fractured. Superficial chip-off fractures of the veneering porcelain were, however, observed in nine patients (34 of 99 units, 34%). CONCLUSION: Results from this 3-year study suggest that implant-supported full-arch Y-TZP FDPs manufactured according to the Cercon technique should be viewed as a treatment alternative cautiously. A better understanding of the factors resulting in chip-off fractures is needed, together with longer follow-up studies involving larger numbers of patients, before the material and technique can be recommended for general use.

The development of high-strength oxide ceramic materials has led to increased interest in all-ceramic fixed dental prostheses (FDPs). Success rates reported in clinical studies on such reconstructions are close to those of porcelain fused to metal (PFM) FDPs. These reconstructions however, are still of limited size and have so far only concerned FDPs supported by natural teeth. Objectives: The purpose of this study was to evaluate the clinical performance of mutli-unit all-ceramic FDPs supported by dental implants. Methods: Ten patients received all-ceramic FDPs designed according to the Cercon® technique and supported by four AstraTech implants in the lower jaw. Nine patients received ten-unit prostheses and one patient received a nine-unit FDP. The FDPs were cemented with Panavia F2.0 onto preparable titanium abutments. The FDPs were evaluated at baseline, twelve, twenty-four and thirty-six months. The surface and marginal integrity were rated according to the California Dental Association (CDA) quality assessment system. Results: At the three-year follow up all FDPs were in use and all patients reported that they were fully satisfied with the treatment. None of the reconstructions had fractured. Superficial cohesive, chip-off, fractures of the veneering porcelain were, however, observed in nine patients. A total of 34 of 99 units (34%) showed such chip-off fractures. Corresponding results for the twelve-month and twenty-four month follow-ups were 14% and 19% respectively. Most patients were unaware of the fractures, some fractures were adjusted by polishing but no FDPs were in need of replacement. Conclusion: Results from this three-year study suggest that multi-unit all-ceramic implant-supported FDPs designed according to the Cercon® technique may be considered a treatment alternative. Better understanding of the factors behind chip-off fractures is necessary togehter with long-term follow-up studies before the material and technique can be recommended for general use.

The purpose of this study was to evaluate the clinical performance of two to five-unit implant-supported all-ceramic reconstructions and to compare the results of two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ). Eighteen patients were treated with a total of 25 two- to five-unit implant-supported reconstructions. Nine patients were given reconstructions of the DZ system and the other nine reconstructions of the InZ system.The reconstructions were cemented with zinc phosphate cement onto preparable titanium abutments and were evaluated after 6 and 12 months. At the 12-month follow-up, all reconstructions were in function; none had fractured. Superficial cohesive (chip-off) fractures were, however, observed in 6 of the 18 patients (8 of 25 reconstructions). Nine units in the DZ group (in 7 of 13 reconstructions) and one in the InZ group (1 of 12 reconstructions) had chip-off fractures. The difference between the two groups regarding frequency of chip-off fractures was statistically significant (P < 0.01). Marginal integrity was rated excellent at 34 abutments (56%) and acceptable at 27 (44%). Results from this 12-month trial suggest that all-ceramic implant-supported fixed partial dentures of two- to five-units may be considered a treatment alternative. When comparing the two ceramic systems under study, however, this study concludes that the DZ system exhibits an unacceptable amount of veneering porcelain fractures and thus cannot be recommended for the type of treatment evaluated in this trial. Further studies and long-term follow-ups must be performed before the materials and technique can be recommended for general use.

Purpose: This Review aimed to evaluate the documented clinical success of zirconia-based crowns in clinical trials. Materials and Methods: Electronic databases were searched for original studies reporting on the clinical performance of tooth- or implant-supported zirconia-based crowns including PubMed, Cochrane Library and Science Direct. The electronic search was complemented by manual searches of the bibliographies of all retrieved full text articles and reviews as well as hand search of the following journals: International Journal of Prosthodontics, Journal of Oral Rehabilitation, International Journal of Oral & Maxillofacial Implants and Clinical Oral Implants Research. Results: The search yielded 3,216 titles. Based on pre-established criteria, 42 full-text articles were obtained. While 16 studies fulfilled the inclusion and exclusion criteria, only 3 randomized controlled trials were reported. Seven studies reported on tooth-supported and four on implant-supported crowns, and 5 studies reported on both types of support. Ten studies on tooth-supported and 7 on implant-supported crowns provided sufficient material for statistical analysis. Life table analysis revealed cumulative 5-year survival rates of 95,9% for tooth-supported and 97,1% for implant-supported crowns respectively. For implant-supported crowns the most common reasons for failure were technical (veneering material fractures). For tooth-supported crowns technical (veneering material fractures, loss of retention) and biological (endodontic/periodontic) reasons for failure were equally common. The most common complications for implant-supported crowns were veneering material fractures and bleeding on probing. For tooth-supported crowns the most common complications were loss of retention, endodontic treatment, veneering material fractures, and bleeding on probing. Conclusion: The results suggest that the success rate of tooth-supported and implant-supported zirconia-based crowns is adequate, similar, and comparable to that of conventional porcelain-fused-to-metal crowns. These results are, however, based on a relatively few studies, many that are not controlled clinical trials. Well-designed studies with large patient groups and long follow-up times are needed before general recommendations for the use of zirconia-based restorations can be provided.

Purpose: To assess and compare the clinical outcomes of three different types of all-ceramic posterior monolithic tooth-supported crowns. Materials and Methods: A total of 71 patients received 90 all-ceramic crowns randomized to be either high-translucency zirconia (ZC), high-translucency zirconia with a partial buccal veneer (ZC-V), or lithium disilicate glass-ceramic (LDS). All treatments were performed by four general dentists. Choice of material was blinded. Baseline and subsequent annual evaluation were based on modified California Dental Association (CDA) criteria. A questionnaire was used to include patient-reported outcomes and to compare them to the crown quality rating performed by dentists. Results: A total of 66 patients with 84 crowns were examined after 3 years. The survival rate was 98.8%. No crowns fractured during the observation period. One ZC-V crown failed due to loss of retention, and three complications were noted: loss of retention occurred in one ZC crown, and two ZC crowns needed to be endodontically treated. There was no significant difference between the different crowns regarding marginal integrity, surface, or anatomical form. Both patients and examining dentists rated the crowns favorably regarding esthetics, patients more than dentists. Conclusion: Posterior lithium disilicate glass-ceramic crowns and translucent zirconia crowns with or without a partial buccal veneer show excellent and promising clinical outcomes from a short-term perspective. Patients and dentists rate the restorations favorably concerning esthetics and function.

The purpose was to evaluate the bond strength between adhesive cement and translucent zirconia in comparison to conventional zirconia. Four brands of translucent zirconia (BruxZir HT, Lava™ Plus, Prettau Anterior, and Prettau Zirconia) and one conventional zirconia (Kavo Everest ZS) were evaluated. Specimens were divided into groups depending on the pretreatment of the cementation surface of the zirconia: as-produced, hydrofluoric acid treatment, or sandblasted. The groups underwent three different procedures of artificial aging: water storage (24 h), 5,000 thermocycles, or long-term aging, (water storage 150 days including 37,500 thermocycles) before shear bond strength testing. Sandblasting treatment increased the bond strength significantly for all the brands of zirconia, irrespective of artificial aging procedures, in comparison to the control group. Bond strength between adhesive cement to translucent zirconia is equivalent to conventional zirconia. Sandblasting creates a cementation surface that is more durable than as-produced or hydrofluoric-acid-treated, irrespective of type of zirconia.

The aim was to make an inventory of the current literature on the clinical performance of tooth- or implant-supported zirconia-based FDPs and analyse and discuss any complications. Electronic databases, PubMed.gov, Cochrane Library, and Science Direct, were searched for original studies reporting on the clinical performance of tooth- or implant-supported zirconia-based FDPs. The electronic search was complemented by manual searches of the bibliographies of all retrieved full-text articles and reviews, as well as a hand search of the following journals: International Journal of Prosthodontics, Journal of Oral Rehabilitation, International Journal of Oral & Maxillofacial Implants, and Clinical Oral Implants Research. The search yielded 4,253 titles. Sixty-eight potentially relevant full-text articles were retrieved. After applying pre-established criteria 27 studies were included. Twenty-three studies reported on tooth-supported and 4 on implant-supported FDPs. Five of the studies were randomized; comparing Y-TZP based restorations with metal-ceramic or other all-ceramic restorations. Most tooth-supported FDPs were FDPs of 3-5units, whereas most implant-supported FDPs were full-arch. The majority of the studies reported on 3-5 year follow-up. Life table analysis revealed cumulative 5-year survival rates of 93.5% for tooth-supported and 100% for implant-supported FDPs. For tooth-supported FDPs the most common reasons for failure were; veneering material fractures, framework fractures and caries. Cumulative 5-year complication rates were 27.6% and 30.5% for tooth- and implant-supported FDPs respectively. The most common complications were veneering material fractures for tooth- as well as implant-supported FDPs. Loss of retention occurred more frequently in FDPs luted with zinc-phosphate or glass ionomer cement compared to those luted with resin cements. The results suggest that the 5-year survival rate is excellent for implant-supported zirconia-based FDPs, despite the incidence of complications, and acceptable for tooth- supported zirconia-based FDPs. These results are, however, based on a relatively small number of studies, especially for the implant-supported FDPs. The vast majority of the studies are not controlled clinical trials and have limited follow-up. Thus interpretation of the results should be made with caution. Well-designed studies with large patient groups and long follow-up times are needed before general recommendations for the use of zirconia-based restorations can be provided.

OBJECTIVE: The aim of this study was to evaluate the influence of combining primers and cements from two different resin cement systems on the microtensile bond strength (muTBS) between zirconia and human dentin.

MATERIALS AND METHODS: A total of 120 specimens of zirconia cemented to dentin were allocated into eight groups based on cement type (RelyX Ultimate or Panavia V5) and primers (Tooth Primer, Clearfil Ceramic Primer and Scotchbond Universal Adhesive) combinations, applied to dentin or ceramic surfaces. Following artificial aging with 5000 thermocycles, muTBS tests were conducted. Statistical analysis was performed using One-way ANOVA and Tukey's post hoc tests (p </= 0.05), and failure modes were assessed.

RESULTS: The Panavia V5 cement system demonstrated the highest bond strength (19.4 +/- 4.4 MPa), significantly higher than the other groups except when RelyX cement was used with Panavia primers (16.9 +/- 3.7 MPa). Cohesive fractures within the cement layer were the predominant failure mode.

CONCLUSIONS: The combination of primers from different adhesive cement system brands may significantly affect the bonding effectiveness. Therefore, using products from a single product line of the same adhesive cement system, and following the manufacturer's recommendations for indications and use, is crucial for a more predictable clinical outcome.

OBJECTIVE: Technical complications such as veneer fractures are more common in implant-supported than tooth-supported restorations. The underlying causes have not been fully identified. The aim of this study was to evaluate whether misfit between the restoration and the implant may affect the risk of veneer fractures. MATERIALS AND METHODS: Twenty standardized five-unit implant-supported metal-ceramic fixed dental prostheses (FDP)s were manufactured and fixed in acrylic blocks. The test group consisted of ten FDPs fixed with a 150-μm misfit at the distal abutment. The remaining ten FDPs were fixed without misfit and acted as a control group. All FDPS underwent cyclic loading for a total of 100,000 cycles at 30-300 N. The FDPs were checked for cracks or chip-off fractures regularly. After cyclic load, the retorque value of all abutment screws was checked. RESULTS: Cracks within the veneering porcelain were noted in nine FDPs in the test group and one FDP in the control group. This difference was statistically significant (P < 0.001). Fractures of the veneering porcelain occurred in three FDPs in the test group. No fractures occurred in the control group. This difference was not statistically significant. There were no significant differences in retorque values neither between the groups nor between different abutment positions in the FDPs. CONCLUSIONS: Within the limitations of this in vitro pilot trial, it is suggested that misfit between a restoration and the supporting implant may increase the risk of cracking and/or chipping of the veneering porcelain for metal-ceramic FDPs.