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Orthodontic retention: studies of retention capacity, cost-effectiveness and long-term stability
Malmö högskola, Faculty of Odontology (OD).
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Retention strategies, cost-effectiveness and long-term stability oftreatment outcome are essential aspects of orthodontic treatmentplanning.The overall aim of this thesis was to compare and evaluate threedifferent retention strategies, with special reference to short- andlong-term clinical stability and cost-effectiveness. The approach wasevidence-based, hence randomized controlled methodology was usedin order to generate high levels of evidence.This thesis is based on four studies:Papers I and II are based on randomized controlled trials, evaluatingthe stability of treatment outcome after one and two years of retention,using three different retention strategies: a maxillary vacuum-formedretainer combined with a mandibular canine-to-canine retainer; amaxillary vacuum-formed retainer combined with stripping of themandibular anterior teeth and a prefabricated positioner.Paper III presents a cost-minimization analysis of two years ofretention treatment.Paper IV is based on a randomized controlled trial documentingthe results five years post-retention.The following conclusions were drawn:Papers I and II• From a clinical perspective, asssessment after one year ofretention disclosed that the three retention methods weresuccessful in retaining the orthodontic treatment results.• After two years of retention, all three retention methods wereequally effective in controlling relapse at a clinically acceptablelevel.• Most of the relapse occurred during the first year of retention;only minor or negligible changes were found during the secondyear.• The subjects were grouped according to the level ofcompliance (excellent or good). After two years of retentionthere was a negative correlation between growth in bodyheight and relapse of mandibular LII in the group of subjectswith excellent compliance. The group with good complianceshowed a positive correlation (Paper II, Figure 3).• After two years of retention, growth in body height, initialcrowding and gender had no significant influence onmandibular LII (Paper II, Figure 4 and Table 4).Paper III• The cost minimization analysis disclosed that although thethree retention methods achieved clinically similar results, theassociated societal costs differed.• After two years of retention, the vacuum-formed retainer(VFR) in combination with a canine-to-canine retainer (CTC)was the least cost-effective retention appliance.Paper IV• After five years or more out of retention, the three retentionmethods had achieved equally favourable clinical results.Key conclusionsand clinical implicationsThis study compared the short- and long-term outcomes of orthodonticretention by three different methods: a maxillary vacuum-formedretainer combined with a mandibular canine-to-canine retainer;a maxillary vacuum-formed retainer combined with stripping ofthe mandibular anterior teeth and a prefabricated positioner. Allmethods gave equally positive clinical results in both the short-term,i.e. after one and two years of retention, and in the long-term, fiveyears or more post-retention. After two years of retention, the level of compliance affected theretention treatment result. However, no such effect was shown forbody height, the severity of initial crowding or gender.Today, there is increasing emphasis on the importance of economicaspects of healthcare. Of the three methods evaluated in this study,the least cost-effective, after two years of retention, was a vacuumformedretainer combined with a bonded canine-to-canine retainer.The clinical implication of this finding is that in patients meetingthe inclusion criteria, interproximal stripping of the mandibularanterior teeth, or the use of a prefabricated positioner, are highlyappropriate alternatives to a mandibular bonded canine-to-canineretainer.The overall conclusions are that there are a number of effectiveretention methods available and the clinician is not limited to routineuse of a bonded mandibular canine-to-canine retainer. The mostappropriate retention method should be selected on an individual,case to case basis, taking into account such variables as orthodonticdiagnosis, the expected level of patient compliance, patient preferencesand financial considerations.

Place, publisher, year, edition, pages
Malmö University, Faculty of Odontology , 2014. , p. 66
Series
Swedish Dental Journal : Supplement, ISSN 0348-6672 ; 236
National Category
Dentistry
Identifiers
URN: urn:nbn:se:mau:diva-7719Local ID: 18050ISBN: 9789171046031 (print)ISBN: 9789171046048 (print)OAI: oai:DiVA.org:mau-7719DiVA, id: diva2:1404659
Available from: 2020-02-28 Created: 2020-02-28 Last updated: 2022-06-27Bibliographically approved
List of papers
1. Evaluation of orthodontic treatment after 1 year of retention - a randomized trial
Open this publication in new window or tab >>Evaluation of orthodontic treatment after 1 year of retention - a randomized trial
2010 (English)In: European Journal of Orthodontics, ISSN 0141-5387, E-ISSN 1460-2210, Vol. 32, no 5, p. 542-547Article in journal (Refereed)
Abstract [en]

The aim of this study was to use a randomized controlled trial methodology to evaluate and compare three different retention methods. The capacity of the retention methods to retain orthodontic treatment results was in this first phase analysed on a short-term basis, i.e. after 1 year of retention. The subjects were recruited from adolescents undergoing fixed appliance treatment at an orthodontic clinic in the National Health Service (NHS) in Sweden between 2001 and 2007. Seventy-five patients (45 girls and 30 boys with a mean age of 14.4 years at the start of retention) were randomized into three retention systems; a vacuum-formed retainer in the maxilla and bonded canine-to-canine retainer in the mandible (group V-CTC), a vacuum-formed retainer in the maxilla combined with stripping of the 10 proximal surfaces of the lower mandibular anterior teeth (group V-S), and a prefabricated positioner covering the teeth in the maxilla and mandible (group P). The main outcome measures were: Little's irregularity index (LII), intercanine and intermolar width, arch length, overjet, and overbite. Registrations were made before orthodontic treatment, when the fixed orthodontic appliance was removed, and after 12 months in retention. Differences in means between groups were tested by one-way analysis of variance. After 1 year of retention, no clinically significant difference in retention capacity was found between the three retention methods. Small but significant differences (P < 0.05) were observed between the V-CTC and V-S groups regarding mandibular canine width, mandibular arch length, and overbite. In group P, two patients failed to co-operate.

National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-15687 (URN)10.1093/ejo/cjp145 (DOI)000282426900009 ()20080961 (PubMedID)2-s2.0-77957763491 (Scopus ID)10388 (Local ID)10388 (Archive number)10388 (OAI)
Available from: 2020-03-30 Created: 2020-03-30 Last updated: 2024-02-05Bibliographically approved
2. A randomized controlled trial of three orthodontic retention methods in Class I four premolar extraction cases: stability after 2 years in retention
Open this publication in new window or tab >>A randomized controlled trial of three orthodontic retention methods in Class I four premolar extraction cases: stability after 2 years in retention
2013 (English)In: Orthodontics & craniofacial research, ISSN 1601-6335, E-ISSN 1601-6343, Vol. 16, no 2, p. 105-115Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: To evaluate three different retention methods in compliant patients after 2 years of retention. DESIGN: Three group randomized controlled trial. MATERIALS AND METHODS: The sample was recruited from patients having their fixed appliance treatment between 2001 and 2007. Seventy-five patients (45 girls and 30 boys with a mean age of 14.4 years at start of retention) were randomized into three retention methods: vacuum-formed retainer in the maxilla and bonded canine-to-canine retainer in the mandible (Group V-CTC), vacuum-formed retainer in the maxilla combined with stripping of the 10 proximal surfaces of the lower mandibular anterior teeth (Group V-S) and prefabricated positioner covering the teeth in the maxilla and the mandible (Group P). The following linear measurements were performed: Little's irregularity index (LII), intercanine width, intermolar width, arch length, overjet, overbite and body height growth. Registrations were made before orthodontic treatment, at start of retention, after 12 and finally 24 months in retention. Differences in means between groups were tested by one-way analysis of variance (SPSS). RESULTS: After 2 years all three retention methods were successful in retaining orthodontic treatment results. The major part of relapse took place during the 1st year of retention. CONCLUSIONS: All 3 types of retention methods were equally effective in controlling relapse to a clinically acceptable level.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
Keywords
orthodontics, RCT, retention methods, treatment outcome
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-15871 (URN)10.1111/ocr.12011 (DOI)000317289600005 ()23324112 (PubMedID)2-s2.0-84875851437 (Scopus ID)16461 (Local ID)16461 (Archive number)16461 (OAI)
Available from: 2020-03-30 Created: 2020-03-30 Last updated: 2024-02-05Bibliographically approved
3. A cost-minimization analysis of an RCT of three retention methods
Open this publication in new window or tab >>A cost-minimization analysis of an RCT of three retention methods
2014 (English)In: European Journal of Orthodontics, ISSN 0141-5387, E-ISSN 1460-2210, Vol. 36, no 4, p. 436-441Article in journal (Refereed) Published
Abstract [en]

SUMMARY BACKGROUND: There are few cost evaluation studies of orthodontic retention treatment. The aim of this study was to compare the costs in a randomized controlled trial of three retention methods during 2 years of retention treatment. MATERIALS/METHODS: To determine which alternative has the lower cost, a cost-minimization analysis (CMA) was undertaken, based on that the outcome of the treatment alternatives was equivalent. The study comprised 75 patients in 3 groups consisting of 25 each. The first group had a vacuum-formed retainer (VFR) in the maxilla and a cuspid retainer in the mandible (group V-CTC), the second group had a VFR in the maxilla combined with stripping of the incisors and cuspids in the mandible (group V-S), and the third group had a prefabricated positioner (group P). Direct cost (premises, staff salaries, material and laboratory costs) and indirect costs (loss of time at school) were calculated. Societal costs were defined as the sum of direct and indirect costs. RESULTS: The societal costs/patient for scheduled appointments for 2 years of retention treatment in group V-CTC were €497, group V-S €451 and group P €420. Societal costs for unscheduled appointments in group V-CTC were €807 and in group V-S €303. In group P, there were no unscheduled appointments. CONCLUSIONS/IMPLICATIONS: After 2 years of retention in compliant patients, the cuspid retainer was the least cost-effective retention appliance. The CMA showed that for a clinically similar result, there were differences in societal costs, but treatment decisions should always be performed on an individual basis.

Place, publisher, year, edition, pages
Oxford University Press, 2014
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-6552 (URN)10.1093/ejo/cjt070 (DOI)000343323800012 ()24084630 (PubMedID)2-s2.0-84905652863 (Scopus ID)17558 (Local ID)17558 (Archive number)17558 (OAI)
Available from: 2020-02-28 Created: 2020-02-28 Last updated: 2024-02-05Bibliographically approved
4. Five-year postretention outcomes of three retention methods: a randomized controlled trial
Open this publication in new window or tab >>Five-year postretention outcomes of three retention methods: a randomized controlled trial
2015 (English)In: European Journal of Orthodontics, ISSN 0141-5387, E-ISSN 1460-2210, Vol. 37, no 4, p. 345-353Article in journal (Refereed) Published
Abstract [en]

Objective: Comparison of three different retention strategies 5 years or more postretention. Design, Setting, and Participants: Randomized, prospective, single-centre controlled trial. Forty-nine patients (33 girls and 16 boys) were randomly assigned to one of three retention methods during 2 years by picking a ballot shortly before start of retention treatment. Inclusion criteria were no previous orthodontics, permanent dentition, normal skeletal sagittal, vertical, and transversal relationships, Class I dental relationship, space deficiencies, treatment plan with extractions of four premolars followed by fixed straight-wire appliance. Maxillary and mandibular Little's irregularity index (LII), intercanine and intermolar width, arch length, and overbite/overjet were recorded in a blinded manner, altogether 10 measurements on each patient. Significant differences in means within groups assessed by t-test and between groups by one-way analysis of variance. Interventions: Retention methods: removable vacuum-formed retainer (VFR) covering the palate and the maxillary anterior teeth from canine-to-canine and bonded canine-to-canine retainer in the lower arch (group V-CTC); maxillary VFR combined with stripping of the lower anterior teeth (group V-S); and prefabricated positioner (group P). Results: Maxillary mean LII ranged from 1.8 to 2.6 mm, mean intercanine width 33.6-35.3 mm with a significant difference between groups V-S and P, mean intermolar width 46.8-47.4 mm and mean arch length 21.8-22.8 mm. Mandibular mean LII ranged from 2.0 to 3.4 mm with a significant difference between groups V-S and P, mean intercanine width from 25.4 to 26.6 mm, mean intermolar width from 40.8 to 40.9 mm and mean arch length from 16.9 to 17.3 mm. Mean overbite ranged from 1.8 to 2.7 mm and mean overjet from 3.7 to 4.1 mm. Limitations: A single centre study could be less generalizable. Conclusions: The three retention methods disclosed equally favourable clinical results.

Place, publisher, year, edition, pages
Oxford University Press, 2015
Keywords
Oral surgery & medicine, Dentistry
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-15807 (URN)10.1093/ejo/cju063 (DOI)000359669100001 ()25452629 (PubMedID)2-s2.0-84939605358 (Scopus ID)20064 (Local ID)20064 (Archive number)20064 (OAI)
Available from: 2020-03-30 Created: 2020-03-30 Last updated: 2024-02-05Bibliographically approved

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