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The present systematic review was done to assess the available literatures on changes in the number of occlusal contacts (NOC), occlusal contact surface areas, and occlusal force distribution (OFD) with vacuum-formed retainers (VFRs) or clear overlay retainers during retention and to compare them with other retainers. Six electronic databases (Web of Science, Scopus, PubMed, Cochrane Library, Lilacs, and Google Scholar) were searched. Randomized controlled trials (RCTs) and controlled clinical trials (CCTs) reporting on occlusal contact changes with VFRs were included. A total of nine articles were included in this review: three RCTs, five prospective controlled trials (PCTs), and one CCT. The Cochrane risk of bias tool and ROBINS-I tool were used for risk of bias assessment. The three RCTs showed moderate risk of bias, and out of five CCTs, four showed low risk of bias, and one showed moderate risk of bias. One CCT showed a low risk of bias in the ROBINS-I tool. Two out of four studies reported improved occlusal surface area (OSA) with VFRs when assessed at the end of six months and 12 months; one out of four studies reported improved NOC; and one study reported a decrease in OFD anteriorly and an increase in OFD posteriorly after two months of retention. On comparison between the groups, the other retainer groups showed more NOCs compared to VFRs. The limited available evidence suggests an increase in OSA and no change in NOCs and OFD with VFRs during retention. No significant differences between VFRs and other retainers for OSA and OFD were noted, and more NOCs were noted for other retainer groups., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Singh et al.)

Objective: This single center parallel, randomized controlled trial aimed to determine the propensity of microbial adherence on vacuum-formed retainers (VFRs) with different surface roughness imprints., Materials and Methods: Thirty-six patients debonded from fixed appliances at a teaching institution were allocated by block randomization stratified for gender to three groups [VFRs fabricated on conventional, fused deposition modeling (FDM) or stereolithography apparatus (SLA) working models]. Participants wore the VFRs for three months full-time followed by three months part-time. VFRs were collected after each follow-up for Streptococcus and yeast counts. Surface roughness was measured indirectly on the working models using a 3D optical surface texture analyzer. Blinding was not feasible due to appliance appearance. The trial was registered [NCT03844425 ( ClinicalTrials.gov )] and funded by the Universiti Malaya Dental Postgraduate Research Grant (DPRG/14/19)., Results: Thirty participants (eleven conventional, ten FDM, and nine SLA) were analyzed after six dropped out. No harms were reported. Microbial counts between the groups were not significantly different. There were more microbes in the lower VFRs than upper VFRs (total count: p<0.05; effect size, 0.5 during full-time wear and 0.4 during part-time wear). SLA had significantly (p<0.05) smoother surface than FDM (effect size, 0.3) and conventional models (effect size, 0.5). Microbial adherence was not associated with working model surface roughness., Conclusion: Microbial adherence on VFRs was not influenced by degree of surface roughness imprints from working models., Clinical Relevance: 3D printed models can be used to make VFRs. Lower VFRs tended to accumulate oral microbes, potentially increasing the oral health risk in the lower arch., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Diligent wear of removable orthodontic retainers requires prolonged adherence and is invariably necessary to preserve optimal results. Patient-informed behaviour-change interventions represent a promising and novel means of enhancing adherence to removable retainer wear. The aim of this study was to describe the development of a patient-informed mobile application designed to enhance retainer wear., Methods: App development encompassed consideration of participant preferences, social media posts, available interventions and behaviour change theories. Qualitative methods including analysis of publicly-available retainer-related posts on Twitter (n = 827) and one-to-one interviews were undertaken. Audio-recorded one-to-one interviews were undertaken to identify patient preferences in relation to features, content and design of the application. A criterion-based purposive sample of participants wearing vacuum-formed retainers for at least 4 years was used (n = 15). Thematic analysis of transcribed data was undertaken. These data were triangulated to inform design and content of the application., Results: The need to facilitate communication with the treating clinician, responsive reminder and tracking systems, and access to useful and engaging written and visual information, in addition to other personalised and interactive features were considered important. Concerns related to retainer wear shared on Twitter informed an exhaustive list of frequently-asked questions. Application features were mapped to relevant theoretical constructs. Determinants of existing behavioural change theories were also used to link application features to retainer wear and maintenance., Conclusions: A holistic process involving both patient and professional input can be useful in informing the development of mobile applications. The orthodontic application ("My Retainers") will undergo further scrutiny in relation to its effectiveness in inducing behavioural change and concerning patient experiences prior to finalisation., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Objective: To explore factors influencing adherence to vacuum-formed retainer wear over a minimum period of four years., Design: A qualitative study based on a randomised controlled trial assessing the effectiveness of orthodontic retainers., Setting: Institute of Dentistry, Queen Mary University of London., Participants: Fifteen participants wearing vacuum-formed retainers for at least four years., Methods: One-to-one semi-structured interviews were undertaken on a criterion-based purposive sample of participants wearing vacuum-formed retainers. The interviews were audio-recorded, transcribed verbatim and analysed using Framework Methodology., Results: High self-reported levels of adherence in the early stages of retention were linked to a desire to maintain orthodontic outcomes and the negative perception of potential post-treatment changes. However, adherence typically reduced over time due to a combination of factors including the negative impact of retainers on quality of life and pragmatic issues related to retainer wear. Network support was found to be important in the short and long term, with instances of self-directed wear and negative beliefs concerning the importance of retainer wear and predisposition to post-treatment changes. Lack of follow-up appointments and immaturity of participants prompted independent decisions to cease retainer wear., Conclusions: Six key influencers of prolonged adherence with vacuum-formed retainer wear were identified. Future strategies to improve adherence should account for these while also being responsive to time elapsed since debond and patient age.

Objective: To evaluate retention protocols and use of vacuum-formed retainers (VFRs) among specialist orthodontists., Design: Postal/electronic (e-) questionnaire., Setting: Republic of Ireland., Participants: Members of the Dental Council of Ireland Specialist Register of Orthodontists and/or Orthodontic Society of Ireland., Methods: A pilot-tested questionnaire was distributed to 123 eligible specialist orthodontists. Questions addressed respondent demographics, preferred retainer choice in the maxillary and mandibular arches, prescribed wear protocols, VFR characteristics and factors influencing retainer choice. Statistical analyses were performed using PASW® version 18., Results: The response rate was 82%. VFRs were the most commonly chosen retainer, prescribed by 53% of respondents in the maxilla and 33% in the mandible. Full-time followed by part-time wear of removable retainers (RRs) was the wear protocol favoured by the majority (70-76%). Full occlusal coverage was the VFR design favoured by 93%. VFR sheet thicknesses of 1.0 mm (68%) and 0.75 mm (16%) were most commonly prescribed. Seventeen per cent were aware that their patients used their VFRs as a receptacle for dental bleaching gel. Life-time wear of retainers was advised by 67-78%. The operator factor that most influenced retainer choice was the pre-treatment situation (88%)., Conclusions: VFRs were the most common retainer choice in the maxilla and mandible with full-time wear followed by part-time wear of RRs favoured by most. Full occlusal coverage with a thickness of 1.0 mm was the VFR design prescribed by the majority. More than one in six specialist orthodontists were aware that their patients used their VFRs as a receptacle for dental bleaching gel.