Performance of clear vacuum-formed thermoplastic retainers depending on retention protocol: a systematic review

The Common Retention Practices Among Orthodontists from Different Countries

Objective

To investigate the most common retention practices, factors influencing the retention protocol, and the differences among orthodontists regarding retention practices.

Methods

An online validated questionnaire was anonymously sent to 3,000 orthodontic residents and clinicians. The survey consisted of 19 questions regarding the participants' demographics, prescribed retention appliances, factors affecting retention appliance choices, and adjunctive retention procedures. Descriptive statistics, Chi2 and Kendall's Tau-b tests were applied.

Results

Five hundred fifty-five orthodontic residents and clinicians, 53.3% males and 46.7% females, completed the survey, indicating a response rate of 18.5%. Although participants' demographics, type of treatment and pre-treatment malocclusion influence the choice of retention protocols, thermoplastic retainers (TR) were the most popular retention regime for the maxillary arch for both adults (47.4%) and adolescents (42.3%). Bonded retainers (BR) were the favored option for the mandibular arch (44.9% of adults and 40.7% of adolescents). The degree of arch expansion (64.1%) and the degree of interdigitation (50.1%) after treatment were the most influential factors for the choice of the preferred type of retainers by the respondents. 68.6% of the participants thought professional retention guidelines would be useful.

Conclusion

Thermoplastic retainers were the most common retention appliances for adults and adolescents in the maxilla. At the same time, BR was the most favored retainer in the mandibular arch, with clinical experience, practice setting, and malocclusion- and treatment-related factors influencing the type of the chosen appliance. The demographic differences and the uneven participation in the survey need to be considered while interpreting the findings of this study.

Comparison of 2 different wear protocols of vacuum-formed retainers with respect to the conventional parameters and 3-dimensional superimpositional analysis

INTRODUCTION

This study aimed to compare the effectiveness of 2 different wear protocols of vacuum-formed retainers (VFR) in terms of angular and linear displacement of teeth using 3-dimensional (3D) superimpositional analysis and conventional model parameters.

METHODS

The study was conducted on 2 groups, each consisting of 17 patients randomly assigned to the part-time group or full-time group of VFR wearing after a nonextraction treatment. While conventional model measurements were assessed on 3D dental casts, 3D tooth movements were evaluated by digitally superimposed scans of casts acquired at 4-time points (debonding and 1, 3, and 6 months after debonding). Regarding conventional parameters, the difference between time-dependent changes among the groups was tested using the nonparametric Brunner-Langer and parametric linear mixed models. Considering 3D measurements, comparisons of groups were made using the Student t tests.

RESULTS

There were no significant intergroup differences regarding conventional model parameters at any time (P >0.05). Significant intergroup differences were observed regarding angular and linear relapses in the labiolingual direction for maxillary and mandibular incisors, as well as the rotational relapses for maxillary left canine and mandibular right lateral incisor, which were greater in the part-time group in the first month and at the end of 6 months (P <0.05).

CONCLUSIONS

Conventional model parameters appear to play a debatable role in evaluating the effectiveness of a retainer wear regimen. Three-dimensional analysis of tooth movements revealed that part-time VFR wear was less effective in retaining labiolingual and rotational tooth movements for the first month after debonding.

Treatment stability with bonded versus vacuum-formed retainers: a systematic review of randomized clinical trials

BACKGROUND

In orthodontics, the retention phase can be considered challenging and unpredictable. Therefore, evidence obtained from different retention protocols is important to facilitate clinical decision-making.

OBJECTIVES

This systematic review aimed to compare the clinical effectiveness of bonded versus vacuum-formed retainers (VFRs) regarding their capacity to maintain treatment stability, periodontal effects, and failure rates.

SEARCH METHODS AND ELIGIBILITY CRITERIA

Ten databases comprising published and unpublished literature were systematically searched up to August 2021. Randomized clinical trials (RCTs) comparing both retainers were included.

DATA COLLECTION AND ANALYSIS

The risk of bias (RoB) evaluation was performed with the Cochrane Collaboration RoB Tool 2.0. All steps of the screening phase and RoB assessment were performed independently by two reviewers. The Grade of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to evaluate the certainty of the evidence.

RESULTS

Initial database search yielded 923 studies. After duplicates removal and full-text assessment, five RCTs remained. Overall, the studies presented Low RoB, except one study judged with 'Some concerns'. Based on the included studies, on a short-term (3-6 months) and long-term (4 years) basis, bonded retainers (BRs) were more effective to maintain treatment stability than VFRs in the lower arch. However, from 12 to 24 months both retainers presented the same efficacy. In the upper arch, the retainers were equally effective. BRs were associated with greater plaque and calculus accumulation than VFRs after 12 months. The retainers' failure rates were similar in the upper arch on the first year of retention; however, after 2 years VFRs showed significantly greater failure rates. Contrarily, BRs presented greater failure rates in the lower arch than VFRs.

LIMITATIONS

The findings of the included studies may be influenced by different factors related to the unpredictability of relapse.

CONCLUSIONS

Most of the evidence generated in this systematic review derived from a moderate level of certainty. In the lower arch, BRs are more effective than VFRs to maintain treatment stability in the initial 6 months of retention and in the long term. In the upper arch, both retention protocols are equally effective.

REGISTRATION

Regist0ration number: PROSPERO CRD42020199392.

FUNDING

Coordination for the Improvement of Higher Educational Personnel (CAPES, Process code-001).

Assessment of the effect of vacuum-formed retainers and Hawley retainers on periodontal health: A systematic review and meta-analysis

Background

Recently, increasing attention has been paid to the periodontal health of orthodontic patients in the maintenance stage in clinical practice. The focus of this meta-analysis was to compare the effects of vacuum-formed retainers (VFR) and Hawley retainers (HR) on periodontal health, in order to provide a reference for clinical selection.

Methods

From the establishment of the database until November 2020, a large number of databases were searched to find relevant randomized control trials, including the Cochrane Library databases, Embase, PubMed, Medline via Ovi, Web of Science, Scopus, Grey Literature in Europe, Google Scholar and CNKI. Related literature was manually searched and included in the analysis. Two researchers screened the literature according to relevant criteria. The size of the effect was determined using RevMan5.3 software, and the mean difference and 95% confidence intervals (CI) were used to estimate the results using a random effects model.

Results

This meta-analysis included six randomized controlled trials involving 304 patients. The results of the meta-analysis showed that there was no statistical difference in sulcus probing depth status between the VFR group and the HR group, including at 1, 3, and 6 months. Compared with the VFR group, the HR group showed a lower gingival index at 1 month (mean difference = 0.12, 95%CI: 0.06 to 0.19) and 3 months (mean difference = 0.11, 95%CI: 0.06 to 0.17), while there was no statistically significant difference at 6 months (mean difference = 0.10, 95%CI: -0.07 to 0.27). The plaque index of the HR group also showed a good state at 1 month (mean difference = 0.06, 95%CI: 0.01 to 0.12), 3 months (mean difference = 0.12, 95%CI: 0.08 to 0.16), and 6 months (mean difference = 0.19, 95%CI: 0.09 to 0.29). Subgroup analysis of PLI showed that when all teeth were measured, PLI status was lower in the HR group at 6 months (mean difference = 0.32, 95%CI: 0.18 to 0.46). PLI status was also low for the other teeth group (mean difference = 0.15, 95%CI: 0.08 to 0.22).

Conclusion

Our meta-analysis showed that patients using the Hawley retainer had better periodontal health compared with those using vacuum-formed retainers. However, more research is needed to look at the periodontal health of patients using these two retainers.

The origin and evolution of the Hawley retainer for the effectiveness to maintain tooth position after fixed orthodontic treatment compare to vacuum-formed retainer: A systematic review of RCTs

OBJECTIVE

This systematic review aims to summarize the effectiveness and patient compliances of Hawley retainer (HR) compared to vacuum-formed retainers (VFR) and provide the best clinical evidence related to the use of these retainers for maintaining tooth position following fixed orthodontic appliance so that orthodontists can decide which are the most appropriate methods and retainers to use for each individual patient.

MATERIALS AND METHODS

We searched the Cochrane Library, EMBASE, PubMed, Web of Science, Orthodontic journals, and relevant articles for eligible studies. Only RCTs studies were included; no restrictions on publication status or language were applied until May 20, 2019. We collected the study related to the effectiveness of these two retainers. Furthermore, patient-reported outcomes, survival time, cost-effectiveness, occlusal contact, and adverse effect on gingival and speech articulation were also collected.

RESULTS

We finally included fifteen articles in the qualitative synthesis. No significant difference was observed in patients who had worn the retainers on a full-time or part-time, basis in both HR and VFR in terms of the change in arch widths and arch lengths. VFR appeared to be better at preventing relapses of incisor irregularity than HR. Patient satisfaction with VFR was higher than with HR, and there was no difference in survival rates for both types of retainers. In terms of cost-effectiveness, occlusal contacts, and gingival health, there were a few studies with limited evidence to compare these retainers. For speech articulation, VFR was less affected in comparison to HR.

CONCLUSIONS

We found that wearing VFR provides better relapse prevention of incisor irregularity than HR in both arches, indicating their usefulness in clinical practice. However, there is no evidence to show that the pattern of time duration wearing these retainers provides excellent stability. Overall, there are insufficient high-quality RCTs to provide additional evidence, and further high-quality RCTs research is needed.

Development of a clinical practice guideline for orthodontic retention

OBJECTIVES

To develop a clinical practice guideline (CPG) for orthodontic retention (OR).

MATERIALS AND METHODS

The CPG was developed according to the AGREE II instrument and EBRO (Dutch methodology for evidence-based guideline development). Reporting was done according the RIGHT statement. A Task Force developed clinical questions regarding OR. To answer these questions, a systematic literature search in PubMed and EMBASE was performed. Two independent researchers identified and selected studies, assessed risk of bias using Cochrane RoB tool and rated quality of evidence using GRADE. The Task Force formulated considerations and recommendations after discussing the evidence. The concept CPG was sent for commentary to all relevant stakeholders.

RESULT

One systematic review-with 15 studies-met the inclusion criteria. In case of low evidence and lack of outcome measures, expert-based considerations were developed. Over four meetings, the Task Force reached consensus on considerations and recommendations, after which the concept CPG was ready for the commentary phase. After processing the comments, the CPG was presented to the Dutch Association of Orthodontists, whereafter authorization followed.

LIMITATIONS

The paucity of evidence-based studies concerning OR and the reporting of measurable patient outcomes.

CONCLUSION

This CPG offers practitioner recommendations for best practice regarding OR, may reduce variation between practices and assists with patient aftercare. A carefully chosen retention procedure for individual patients, combined with clear information and communication between orthodontist, dentist and patient will contribute to long-term maintenance of orthodontic treatment results.

A systematic review of orthodontic retention systems: The verdict

INTRODUCTION

Retention during both the active and passive phases of treatment has given rise to numerous publications concerning its efficacy, the range of systems available and its variability over time. There are currently many different retention protocols regularly used by orthodontists; however, their efficacy and duration are still subject to debate. There is as yet no consensus as to which retention protocol is the most effective or for how long the retention device needs to be worn. The aim of this research was to perform a systematic review of the scientific literature in order to evaluate the efficacy of the different retention systems and clinical protocols among those most widely used, so as to make recommendations beneficial to both patient and practitioner.

MATERIALS AND METHODS

A search of the literature was performed in the following databases: PubMed (MEDLINE), ScienceDirect and Cochrane Library. The search was limited to publications in English and French during the period 2006-2016.

RESULTS

Out of 1952 references initially identified, 17 articles corresponded to our inclusion criteria. The results show that: fixed retention is more effective than removable retainers for the maintenance of incisor alignment during the first six months of retention; there is no significant difference in efficacy between the different fixed retention systems; there is no significant difference in efficacy between the vacuum-formed systems and the Hawley retainer; part-time use of removable retainers (between 8-10h/day) is sufficient; the most widely used retention protocol combines a vacuum-formed splint or Hawley retainer in the upper arch with mandibular fixed retention.

CONCLUSION

Despite the large number of studies devoted to orthodontic retention only a few articles corresponded to the methodological criteria of bio statistical analysis. Also, on account of the variations in experimental protocols, the levels of proof relating to the efficacy of different systems are very weak. Research into this topic should first seek to normalize methods of analysis and then perform randomized controlled long-term trials to shed light on this problem.

Periodontal health and compliance: A comparison between Essix and Hawley retainers

INTRODUCTION

Many studies on removable retainers have focused on retention efficacy and characteristics. However, studies on plaque accumulation, periodontal health, breakages, and patient compliance are still lacking. Thus, in this study, we aimed at evaluating these parameters in 2 groups of young patients wearing Essix or Hawley retainers for a 6-month period.

METHODS

Seventy subjects were included. Periodontal health was investigated by measuring the plaque, gingival, calculus, and bleeding on probing indexes. Evaluations were performed at 1, 3, and 6 months of wearing. Accumulation of plaque on the retainers was also evaluated. Furthermore, compliance on wearing retainers and breakage data were collected by specific questionnaires.

RESULTS

Subjects wearing Essix retainers had significantly higher levels of plaque, gingival, and calculus indexes and increased percentages of bleeding sites, compared with subjects wearing Hawley retainers. The Essix group also had increased accumulations of plaque and calculus on the retainers. Nonetheless, subjects of the Essix group had better overall experiences, self-perceptions, and comfort compared with those of the Hawley group. Essix retainers had higher incidences of little and serious breakages compared with Hawley retainers.

CONCLUSIONS

Our results suggest that Essix retainers are well accepted by patients for their esthetic and oral comfort characteristics. However, Essix retainers may cause greater accumulations of plaque on both teeth and retainers, presumably because of inhibition of the cleaning effect of saliva caused by the thermoplastic material or the reduced opportunity for good hygiene on the retainer.