This clinical randomized study aimed to evaluate the early plaque formation on nonresorbable polytetrafluoroethylene (PTFE) membranes having either a dense (d‐PTFE) or an expanded (e‐PTFE) microstructure and exposed to the oral cavity.

BACKGROUND Prefabricated myofunctional appliances (PMAs) are widely advocated for correcting Class II division I malocclusion. However, their effectiveness is associated with a high amount of uncertainty within contemporary literature. OBJECTIVES The aim of this review was to systematically examine the available literature regarding the effectiveness of PMAs in treating Class II division 1 malocclusion in children and adolescents. SEARCH METHODS Comprehensive unrestricted electronic searches in multiple databases as well as manual searches were conducted up to August 2018. SELECTION CRITERIA Randomized controlled trials (RCTs) and non-randomized studies (NRS) matching the eligibility criteria. DATA COLLECTION AND ANALYSIS Two independent review authors were directly involved in study selection, data extraction, and bias assessment. The Cochrane risk of bias tool and the ROBINS-I tool were used for assessing the risk of bias. Quantitative pooling of the data was undertaken with a random-effects model with its 95% confidence interval (CI). RESULTS Three RCTs comparing PMAs to activators and three NRS comparing PMAs to untreated controls met the inclusion criteria. On a short-term basis, exploratory quantitative synthesis indicated that the activators were more effective than the PMAs in correcting overjet with a mean difference of (1.1 mm; 95% CI: 0.44 to 1.77). On a long-term basis, there were no significant differences between the two appliances. Qualitative synthesis indicated less favorable soft tissue changes as well as patient experiences and compliance with the PMAs when compared to the activators. However, PMAs were associated with reduced costs compared to customized activators and modest changes when compared to untreated controls. CONCLUSIONS On a short-term basis, low quality of evidence suggests that PMAs were generally less effective than the activators in treating Class II division 1 malocclusion. The main advantage of PMAs seems to be their reduced costs. These results should be viewed with caution, as a definitive need for high-quality long-term research into this area is required. REGISTRATION PROSPERO (CRD42018108564).

Objective The purpose of this study was to assess and relate the societal costs of reducing large overjet with a prefabricated functional appliance (PFA), or a slightly modified Andresen activator (AA), using a cost-minimization analysis (CMA). Design, settings, and participants A multicentre, prospective, randomized clinical trial was conducted with patients from 12 general dental practices. Ninety-seven patients with an Angle Class II, division 1 malocclusion, and an overjet of ≥6 mm were randomly allocated by lottery to treatment with either a PFA or an AA. The PFA and AA groups consisted of 57 and 40 subjects, respectively. Blinding was not performed. Duration of treatment, number of scheduled/unscheduled appointments, and retreatment were registered. Direct and indirect costs were analysed with reference to intention-to-treat (ITT), successful (S), and unsuccessful (US) outcomes. Societal costs were described as the total of direct and indirect costs, not including retreatments. Interventions Treatment with a PFA or an AA. Results The direct and societal costs were significantly lower for the PFA than for the AA group. The number of visits was lower in the PFA group, when ITT was considered, and for the US cases as well. No difference in retreatment rate could be seen between the groups. Limitations Costs depend on local factors and thus should not be generalized to other settings. Harms No harms were detected during the study. Conclusion The success rate of the both appliances was low. However, the PFA was the preferred approach for reduction of a large overjet in mixed dentition, since it minimized costs and there were no difference in clinical outcomes between PFA and AA. Registration This trial was registered at 'FoU i Sverige' (http://www.fou.nu/is/sverige), registration number: 97131. Protocol The protocol was not published before trial commencement.

........................................................................................7 SAMMANFATTNING .....................................................................8 PREFACE .............................................................................................9 ABBREVIATIONS ........................................................................... 11 DEFINITIONS IN SHORT ............................................................. 13 INTRODUCTION ........................................................................... 15 Angle Class II Division 1 .................................................................................. 15 Treatment of large overjet ................................................................................. 16 Removable functional appliances ................................................................... 19 Level of evidence ............................................................................................... 25 AIMS .............................................................................................. 29 PATIENTS AND METHODS ........................................................ 31 Subjects (Paper I-IV) ......................................................................................... 31 Methods .............................................................................................................. 32 Ethical approval ................................................................................................. 39 RESULTS .......................................................................................... 41 Treatment effects Paper I .............................................................................. 41 Discomfort and expectations Paper II ......................................................... 44 Perceptions of the treatment – Paper III ........................................................ 45 Treatment costs Paper IV ............................................................................... 47 DISCUSSION .................................................................................... 49 Limitations and strengths ................................................................................ 49 Subjects .............................................................................................................. 52 Treatment effects .............................................................................................. 52 Patient experience of the treatment ............................................................... 55 Cost evaluation .................................................................................................. 57 Clinical significance of the findings ............................................................... 58 CONCLUSION ................................................................................. 61 FUTURE PERSPECTIVES ............................................................. 63 ACKNOWLEDGEMENTS ............................................................. 65 Grants ................................................................................................................. 67 REFERENCES ................................................................................... 69 APPENDIX I, questionnaire ........................................................... 81 APPENDIX II, paper I-IV .............................................................. 87 Paper I ............................................................................................. 89 Paper II ......................................................................................... 101 Paper III ........................................................................................ 111 Paper IV ........................................................................................ 123

Abstract Background: The purpose of this study was to investigate the amount of functional and social discomfort experienced after 1 and 6 months of appliance wear, comparing a slightly modified Andresen Activator (AA) and a Prefabricated Functional Appliance (PFA). Methods: Ninety-seven patients randomly selected by lottery in an AA (40 subjects), and a PFA (57 subjects) group, with an Angle Class II, Division 1 malocclusion, were eligible for the study. One month and 6 months after start of treatment, a questionnaire, addressing discomfort, perception of treatment need and outcome, was used. Results: The response rate was 69% after 1 month, and 45% after 6 months. The most common discomfort reported was the ‘appliance falling out during sleep’ followed by ’difficulties in remembering it’. The only difference was for pain, which was experienced more extensively in the AA group after 1 month of treatment. The dentist appeared to have the greatest impact on the decision to initiate treatment. Teasing, because of appearance, occurred in 13% of the cases. Conclusions: No difference could be seen between groups for the experience of functional or social discomfort after 6 months of appliance use. Adequate time should be allowed for clarifying treatment difficulties, using treatment need as motivation. Practical implications: The PFA eliminates the need for taking impressions. Furthermore, it can be economically advantageous to both patients and clinicians.

OBJECTIVES The purpose of this study was to compare the clinical effectiveness in reducing large overjet between a prefabricated functional appliance (PFA) and a slightly modified Andresen activator (AA). SETTING AND SAMPLE POPULATION Public Dental Service, Gothenburg, Sweden. PARTICIPANTS, STUDY DESIGN, AND METHODS A multicentre, prospective randomized clinical trial was conducted with patients from 12 general dental practices. One hundred and five patients with an Angle Class II, division 1 malocclusion and an overjet of ≥6mm were eligible for the study. Eight patients were excluded due to various reasons and the sample consisted thus of 97 subjects (44 girls, 53 boys) with a mean age of 10.3 years. The study was designed as intention to treat and the patients were randomly allocated by lottery to treatment with either a PFA or an AA. The PFA and AA group consisted of 57 subjects (28 girls, 29 boys) and 40 subjects (16 girls, 24 boys), respectively. Overjet, overbite, lip seal, and sagittal molar relationship were recorded before, at the end of treatment and 1-year post-treatment. Blinding was not performed. The endpoint of treatment was set to overjet ≤3mm and after this a 6 months retention period followed. RESULTS No significant difference was found in overjet, overbite, sagittal relation, and lip seal between the two groups for the total observation period. The treatment of 40 (70 per cent) patients with PFA and 21 (53 per cent) with AA were considered unsuccessful mainly due to poor compliance. LIMITATIONS No cephalometric records were taken as only patient-centred clinical outcome were used as an indicator for treatment success. The criteria of reduction of overjet to as low as 3mm could have affected the success rate. CONCLUSION No difference in effectiveness could be shown between PFAs and AAs in correcting overjet, overbite, sagittal molar relation, and lip seal. The success rate in treatment with both appliances is, however, low. REGISTRATION This trial was registered in "FoU i Sverige" (http://www.fou.nu/is/sverige), registration number: 97131. PROTOCOL The protocol was not published before trial commencement.

OBJECTIVES The aim of this qualitative study was to explore and describe adolescents' experiences of treatment with removable functional appliances. SETTING AND SAMPLE POPULATION Public Dental Service, Gothenburg, Sweden. MATERIAL AND METHODS Individual interviews focusing on adolescents' experiences of using a removable functional appliance were held with 21 adolescents (12 girls and nine boys). The mean age of the participants was 13.2 years (range 11-15, SD 1.25) at the interview occasion. Interviews were transcribed verbatim and analysed according to a qualitative research approach, phenomenography. RESULTS Outcomes of data analysis emerged in five categories with totally 12 subcategories that describe the adolescents' various conceptions of the treatment. The adolescent's experiences of using removable functional appliance appeared to have a large variation, comprising of the individual approach, feelings and strategies, the dentist role and receiving external support. CONCLUSION Participants developed their own strategies of measurement to see improvement. An active involvement of the adolescents' in the treatment seems to be needed, supported by the dentist at coming appointments, using overjet measurement as a tool for motivation. Furthermore, efforts should be made by clinicians to listen and understand adolescents' needs and requirement before the treatment start.