Clinical and radiographic comparison of the effects of two types of fixed retainers on periodontium - a randomized clinical trial

Keeping the teeth in line: Exploring the necessity of bonded retainers in orthodontics: A narrative review

In most recent studies, long-term retention after orthodontic treatment has been hypothesized that may be necessary to maintain the stability of the dentition and avoid post-treatment changes. The bonded fixed retainer is characterized by its clinical effectiveness, patient acceptance, and lack of patient complaints as compared with a removable retainer. An electronic database (such as PubMed, PubMed Central, Web of Science, Science Direct, Cochrane Library, Scopus, and ResearchGate) has been collected using specific keywords. Of the 152 articles, only randomized clinical trials that investigated different types of fixed retainers or compared fixed with removable retainers were illustrated in tables and included in this review. The present review has gone some way towards enhancing our understanding of the bonded fixed retainer, types, material, bonding methods, and how to improve its the success rate, besides the importance of new technology in fixed orthodontic retention.

Influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth in an intact periodontium - a randomized, clinical controlled trial

OBJECTIVE

Aim of this randomized clinical controlled trial was to evaluate the influence of fixed orthodontic steel retainers on gingival health and recessions of mandibular anterior teeth.

MATERIALS AND METHODS

After end of the orthodontic treatment, patients were randomly assigned into the test (fixed steel retainer) or control group (modified removable vacuum-formed retainer). Periodontal parameters (periodontal probing depth: PPD; recession: REC; bleeding on probing: BOP) as well as plaque and gingival index were assessed on mandibular anterior teeth directly before attaching/handing over the retainer (baseline: BL), 6 and 12 months after orthodontic treatment.

RESULTS

37 patients (test: n = 15, mean age: 16.1±4.2 years; control: n = 17, mean age: 17.1±5.4 years) completed the study. REC and PPD failed to show significant pairwise differences. The number of patients showing gingival health in the area of the mandibular anterior teeth (test: BL n = 10, 6 months n = 9, 12 months n = 11; control: BL n = 10, 6 months n = 16, 12 months n = 15) revealed a significant difference for the intra-group comparison between BL and 6 months in the control group (p = 0.043). The inter-group comparisons failed to show significant differences.

CONCLUSION

Young orthodontically treated patients with fixed steel retainers show in 73.3% healthy gingival conditions after one year which are comparable to the control group (88.2%). Gingival recessions were in a clinically non-relevant range at any time of the examination.

CLINICAL TRIAL NUMBER

DRKS00016710.

Retention procedures for stabilising tooth position after treatment with orthodontic braces

BACKGROUND

Without a phase of retention after successful orthodontic treatment, teeth tend to 'relapse', that is, to return to their initial position. Retention is achieved by fitting fixed or removable retainers to provide stability to the teeth while avoiding damage to teeth and gums. Removable retainers can be worn full- or part-time. Retainers vary in shape, material, and the way they are made. Adjunctive procedures are sometimes used to try to improve retention, for example, reshaping teeth where they contact ('interproximal reduction'), or cutting fibres around teeth ('percision'). This review is an update of one originally published in 2004 and last updated in 2016.

OBJECTIVES

To evaluate the effects of different retainers and retention strategies used to stabilise tooth position after orthodontic braces.

SEARCH METHODS

An information specialist searched Cochrane Oral Health Trials Register, CENTRAL, MEDLINE, Embase and OpenGrey up to 27 April 2022 and used additional search methods to identify published, unpublished and ongoing studies.  SELECTION CRITERIA: Randomised controlled trials (RCTs) involving children and adults who had retainers fitted or adjunctive procedures undertaken to prevent relapse following orthodontic treatment with braces. We excluded studies with aligners.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened eligible studies, assessed risk of bias and extracted data. Outcomes were stability or relapse of tooth position, retainer failure (i.e. broken, detached, worn out, ill-fitting or lost), adverse effects on teeth and gums (i.e. plaque, gingival and bleeding indices), and participant satisfaction. We calculated mean differences (MD) for continuous data, risk ratios (RR) or risk differences (RD) for dichotomous data, and hazard ratios (HR) for survival data, all with 95% confidence intervals (CI). We conducted meta-analyses when similar studies reported outcomes at the same time point; otherwise results were reported as mean ranges. We prioritised reporting of Little's Irregularity Index (crookedness of anterior teeth) to measure relapse, judging the minimum important difference to be 1 mm.

MAIN RESULTS

We included 47 studies, with 4377 participants. The studies evaluated: removable versus fixed retainers (8 studies); different types of fixed retainers (22 studies) or bonding materials (3 studies); and different types of removable retainers (16 studies). Four studies evaluated more than one comparison. We judged 28 studies to have high risk of bias, 11 to have low risk, and eight studies as unclear.  We focused on 12-month follow-up.  The evidence is low or very low certainty. Most comparisons and outcomes were evaluated in only one study at high risk of bias, and most studies measured outcomes after less than a year. Removable versus fixed retainers Removable (part-time) versus fixed   One study reported that participants wearing clear plastic retainers part-time in the lower arch had more relapse than participants with multistrand fixed retainers, but the amount was not clinically significant (Little's Irregularity Index (LII) MD 0.92 mm, 95% CI 0.23 to 1.61; 56 participants). Removable retainers were more likely to cause discomfort (RR 12.22; 95% CI 1.69 to 88.52; 57 participants), but were associated with less retainer failure (RR 0.44, 95% CI 0.20 to 0.98; 57 participants) and better periodontal health (Gingival Index (GI) MD -0.34, 95% CI -0.66 to -0.02; 59 participants). Removable (full-time) versus fixed   One study reported that removable clear plastic retainers worn full-time in the lower arch did not provide any clinically significant benefit for tooth stability over fixed retainers (LII MD 0.60 mm, 95% CI 0.17 to 1.03; 84 participants). Participants with clear plastic retainers had better periodontal health (gingival bleeding RR 0.53, 95% CI 0.31 to 0.88; 84 participants), but higher risk of retainer failure (RR 3.42, 95% CI 1.38 to 8.47; 77 participants). The study found no difference between retainers for caries.  Different types of fixed retainers Computer-aided design/computer-aided manufacturing (CAD/CAM) nitinol versus conventional/analogue multistrand One study reported that CAD/CAM nitinol fixed retainers were better for tooth stability, but the difference was not clinically significant (LII MD -0.46 mm, 95% CI -0.72 to -0.21; 66 participants). There was no evidence of a difference between retainers for periodontal health (GI MD 0.00, 95% CI -0.16 to 0.16; 2 studies, 107 participants), or retainer survival (RR 1.29, 95% CI 0.67 to 2.49; 1 study, 41 participants). Fibre-reinforced composite versus conventional multistrand/spiral wire  One study reported that fibre-reinforced composite fixed retainers provided better stability than multistrand retainers, but this was not of a clinically significant amount (LII MD -0.70 mm, 95% CI -1.17 to -0.23; 52 participants). The fibre-reinforced retainers had better patient satisfaction with aesthetics (MD 1.49 cm on a visual analogue scale, 95% CI 0.76 to 2.22; 1 study, 32 participants), and similar retainer survival rates (RR 1.01, 95% CI 0.84 to 1.21; 7 studies; 1337 participants) at 12 months. However, failures occurred earlier (MD -1.48 months, 95% CI -1.88 to -1.08; 2 studies, 103 participants; 24-month follow-up) and more gingival inflammation at six months, though bleeding on probing (BoP) was similar (GI MD 0.59, 95% CI 0.13 to 1.05; BoP MD 0.33, 95% CI -0.13 to 0.79; 1 study, 40 participants). Different types of removable retainers Clear plastic versus Hawley When worn in the lower arch for six months full-time and six months part-time, clear plastic provided similar stability to Hawley retainers (LII MD 0.01 mm, 95% CI -0.65 to 0.67; 1 study, 30 participants). Hawley retainers had lower risk of failure (RR 0.60, 95% CI 0.43 to 0.83; 1 study, 111 participants), but were less comfortable at six months (VAS MD -1.86 cm, 95% CI -2.19 to -1.53; 1 study, 86 participants). Part-time versus full-time wear of Hawley There was no evidence of a difference in stability between part-time and full-time use of Hawley retainers (MD 0.20 mm, 95% CI -0.28 to 0.68; 1 study, 52 participants).

AUTHORS' CONCLUSIONS

The evidence is low to very low certainty, so we cannot draw firm conclusions about any one approach to retention over another. More high-quality studies are needed that measure tooth stability over at least two years, and measure how long retainers last, patient satisfaction and negative side effects from wearing retainers, such as tooth decay and gum disease.

Fixed and removable orthodontic retainers, effects on periodontal health compared: A systematic review

The aim of this systematic review is to analyze the properties of the different types of orthodontic retainers, identify their differences and define which type of device is most effective and less harmful to periodontal health.

Methods

A literature search was carried out by a reviewer by consulting PubMed, Lilacs, Embase, Medline full text, Scopus, Web of Science, Cochrane library, and Science Direct electronic databases for biomedical and health literature as well as the grey literature and setting up the search from December 2010 without any restriction about articles languages.

Results

The results showed that patients who wear retainers for a long period have significant differences in clinical parameters compared to patients without retainers. The type of retainer chosen also significantly influences the overall periodontal health of patients. Fixed retainers, both glass-fibre reinforced and steel wire retainers, proved to be the retainer type with the highest plaque and calculus accumulation values compared to removable retainers. In addition, among fixed retainers, glass-fibre reinforced retainers proved to be those that mostly promote the plaque and calculus accumulation in the application site.

Conclusion

Fixed retainers are the best devices to maintain the alignment of mandibular anterior teeth in the long term. Among these devices, stainless steel lingual retainers, plain or braided, should remain the first choice. Although they are also susceptible to periodontal complications, their effect on periodontal health can be considered statistically insignificant if compared to glass-fibre reinforced retainers which, showing worse periodontal complications, should not be used.

Comparison of multistranded wire and fiber-reinforced composite retainers effects on periodontium: A randomized clinical trial

INTRODUCTION

Fixed orthodontic retainers are very important for treatment stability; however, adverse effects on the health of periodontium can be caused as a result of deposition of plaque and calculus.

OBJECTIVES

To compare and determine the effects of two mandibular fixed lingual retainers on the periodontal status, and to test the null hypothesis that there would be no significant difference on the periodontium health between the patients using fiber-reinforced composite (FRC) or multistranded wire (MSW) fixed retainers.

METHODS

A total of 60 subjects were recruited, out of which 6 were excluded and 2 dropped out during the study. Hence, 52 subjects with mean age of 21.5 ± 3.6 years were included in the study. The sample was composed by 8 males (15.4%) and 44 females (84.6%). The participants were randomly divided into two groups: Group 1 received fiber-reinforced composite retainer, while Group 2 received multistranded wire retainer. After insertion, plaque index, calculus index, gingival index and bleeding on probing were compared, after three months (T1), six months (T2), nine months (T3) and twelve months (T4), using Mann-Whitney test with p-value ≤ 0.05 as significant.

RESULTS

It could be seen that the health of periodontium deteriorated with the passage of time from T1 to T4 in both group of retainers. However, no statistically significant differences were found between the two groups (p> 0.05).

CONCLUSION

The results of the study indicate that there was no significant difference on the health of periodontium between the patients with FRC and MSW fixed retainers, hence, the null hypothesis was accepted.

Analysis of the effectiveness of the fiber-reinforced composite lingual retainer: A systematic review and meta-analysis

INTRODUCTION

Orthodontic fixed retainers are preferred as they depend less on patient compliance. Recently, researchers tried to use fiber-reinforced composite (FRC) to replace the multistranded stainless-steel wire (MSW) of the fixed retainers to enhance the mechanical properties and esthetics. This systematic review aimed to analyze the effectiveness of the FRC retainers.

METHODS

We searched the electronic databases (May 1, 2021), including Medline, the Cochrane Library, EMBASE, PubMed, Web of Science, and CINAHL. We applied no language or date restrictions in the searches of the databases. Only randomized controlled trials (RCTs) and prospective clinical controlled trials were included. The revised Cochrane risk of bias tool for randomized trials and risk of bias in nonrandomized studies of interventions were used to evaluate the risk of bias in RCTs and non-RCTs, respectively. The outcomes were pooled using Review Manager 5.4. The primary outcome of this review was teeth relapse, and the secondary outcomes were bonded retainer failure rate, adverse effect on oral health, and patient's satisfaction.

RESULTS

Eleven out of 99 studies, which included 873 participants, were used in this review, with the follow-up ranging from 6 months to 6 years. Ten studies compared the FRC retainers with MSW retainers, and 1 study compared FRC retainers with a different fiber material. Ten studies were RCT, and 1 was non-RCT. There was 0.39 less relapse with the FRC retainers than with MSW retainers (mean difference, -0.39; 95% confidence interval [CI], -0.41 to -0.37; P <0.00001). There was no statistically significant difference in the failure rate between the FRC and MSW with the whole retainer as an outcome unit risk ratio of 1.72 (95% CI, 0.57-5.14; P = 0.33) or with the teeth an as outcome unit risk ratio of 0.85 (95% CI, 0.47-1.52; P = 0.58). There was insufficient evidence to conduct the meta-analysis of the adverse effect on oral health and patient satisfaction.

CONCLUSIONS

Low-quality evidence is available to suggest that the effectiveness of the FRC is comparable to the MSW with no significant difference in the failure rate. However, we have very low certainty on these results. It is worth conducting future robust clinical studies to assess the effectiveness of FRC retainers with long follow-up.

Periodontal status in long-term orthodontic retention patients up to 10 years after treatment - a cross-sectional study

OBJECTIVE

To assess periodontal status in long-term orthodontic retention patients and investigate possible risk indicators.

MATERIALS AND METHODS

Plaque index (PI), gingival index (GI), probing pocket depth (PPD), gingival recessions (GR) and calculus were recorded in 211 patients with or without fixed retainers.

RESULTS

Periodontal parameters were within the limits of clinically healthy periodontium. The use of fixed retainers was associated with higher PI in the maxilla (ß = 1.10 [0.37]; p <.05). Older age was associated with higher PI in the mandible (ß = 0.27 [0.11]; p <.05). Smoking was associated with gingival bleeding on both palatal (ß = 0.63 [0.16]; p < .01) and labial sides in the maxilla (ß = 0.46 [0.20]; p <.05). Smoking was also associated with increased prevalence of GR in the mandible (ß = 0.24 [0.07]; p <.01), while use of snuff had similar effect on the labial side in the maxilla (ß = 0.35 [0.08]; p <.01). Higher age (ß = 0.05 [0.02]; p <.05) and the presence of a retainer (ß = 0.23 [0.07]; p < .05) were associated with calculus accumulation on the lingual side in the mandible.

CONCLUSION

The present observational study suggest that long-term fixed retainers alone have no detrimental effect on the periodontium. Additional factors may increase the risk of plaque deposits and increased probing pocket depths. Further prosepective studies are needed to confirm the present outcome.

A comparative assessment of failures and periodontal health between 2 mandibular lingual retainers in orthodontic patients. A 2-year follow-up, single practice-based randomized trial

INTRODUCTION

The objective of this study was to compare the survival rates and periodontal health in patients with 3-strand round twisted (RT) vs 8-strand rectangular braided (RB) fixed retainers bonded to all 6 anterior teeth in the mandible.

METHODS

A total of 133 patients completing orthodontic treatment (median age, 24.6 years; 25th percentile, 17.2 years; 75th percentile, 32.4 years; minimum, 15.1 years; maximum, 49.8 years) were randomly allocated in a 1:1 ratio to receive either an RT or RB wire retainer. Inclusion criteria were all mandibular permanent incisors and canines present, no active caries, no restorations, no fractures on the mandibular incisors and canines, no periodontal disease. Patients with poor oral hygiene before debonding were excluded from the trial. The primary outcome was any first-time retainer failure. Secondary outcomes were periodontal index, bleeding on probing, plaque index, gingival index, and probing depth. Randomization was accomplished with random permuted blocks of size 4, 6, or 8 with allocation concealed in sequentially numbered, opaque, sealed envelopes. Blinding was not possible in this trial. Patients were evaluated at baseline, 3, 6, 12, 18, and 24 months after placement of the retainer. Retainer survival was assessed using Cox regression. Periodontal parameters were reported at each time point and generalised estimating equations were used to assess the effect of treatment, time, tooth and treatment X time interaction on the indices.

RESULTS

Baseline characteristics were similar between groups; in 1 patient, the intervention was discontinued. During 2-year follow-up 37 of 66 (56.1%, RT group) and 32 of 66 (48.5%, RB group) retainers failed at least once (log-rank test, P = 0.55). The adjusted hazard ratio was 0.69 (95% confidence interval, 0.42-1.12; P = 0.13). Neither age nor gender was a predictor of failure. All periodontal parameters (periodontal index, bleeding on probing, plaque index, gingival index, and pocket depth) were comparable between groups and remained relatively stable during follow-up.

CONCLUSIONS

The overall risk for first-time failure was high and amounted to 52.3% (56.1% in the RT group and 48.5% in the RB group). There was no difference in terms of survival or periodontal health between the examined retainers.

What causes failure of fixed orthodontic retention? - systematic review and meta-analysis of clinical studies

BACKGROUND

Orthodontic retention aims to maintain optimal teeth positions after active treatment. The stability is affected by numerous factors, including patients' individual features, thus retention should be adjusted in the most optimal way. Bonding a retainer makes retention less dependent on patient's compliance.

QUESTIONS ARISE

What wire or fiber splint type provides the best treatment stability? What materials should be used to bond the wire or fiber splint? Should be the bonding procedure be direct or indirect? The aim of the study is to assess and synthesize available controlled trials investigating failures of fixed retainers.

METHODS

Literature searches of free text and MeSH terms were performed in Scopus, Web of Science, Embase and PubMed Central in order to find studies, referring to failures of fixed retention (12th February 2021). The keywords were: ("orthodontic retainers AND failure AND wire"). The framework of this systematic review according to PICO was: Population: orthodontic patients; Intervention: fixed orthodontic retainer bonding; Comparison: Different protocols of fixed orthodontic retention applied; Outcomes: failure rate, survival rate. Three different specific scales from the Cochrane Collaboration Handbook were used, according to each study type. Additionally, a meta-analysis was conducted to compare the effectiveness of retention using fiber reinforced composite and multistranded steel wire.

RESULTS

The search identified 177 potential articles: 114 from PubMed, 41 from Scopus, 20 from Web of Science and 2 from Embase. After excluding studies inconsistent with selection criteria, 21 studies were included and subjected to qualitative analysis. The main outcome investigated was failure rate. This systematic review has some potential limitations due to the heterogeneity of design between included studies.

CONCLUSIONS

No retainer is proved to guarantee a perfect stability of dental alignment. The retainer should be bonded to all adherent teeth, preferably with additional use of bonding resin. No wire or fiber splint present superior characteristics concerning failure rate. Fiber reinforced composite retention is more sensitive to operator skills, and with imperfect bonding technique, failure rate is much higher. During the first 6 months after bonding retainer the patient should be under frequent control. The study protocol was registered in PROSPERO database with the number CRD42021233406.

Orthodontic retention protocols: an evidence-based overview

In view of the diversity of orthodontic presentations, a single optimal retention protocol does not exist, with approaches tailored based on pre-treatment characteristics, treatment-induced changes and general patient characteristics. However, orthodontic practitioners should be responsive to the best available evidence to formulate optimal retention protocols in terms of appliance type, design and regimen, in particular. Based on a comprehensive search strategy, we discuss fundamental aspects concerning orthodontic retention of particular interest both to orthodontists and general dentists. These include stability and periodontal outcomes, cost-effectiveness, patient experiences, survival and failure rates of retainers, and the duration of retention.

Fixed retention: pitfalls and complications

Long-term stability of orthodontic treatment results is problematic. Long-term or even lifelong retention with bonded retainers is being increasingly used among clinicians. Bonded retainers can provide an efficient and attractive method of retention, particularly because they require minimal compliance from patients. However, the use of bonded retainers is associated with relatively frequent complications, such as detachments of the adhesive layer or wire fractures, as well as unexpected complications with potentially severe consequences with associated periodontal and general health risks. It is imperative that the whole dental team are aware of these pitfalls and complications, and appreciate how to minimise and address these.

Side effects of twistflex retainers-3D evaluation of tooth movement after retainer debonding

PURPOSE

Evaluation of tooth movement after retainer debonding in retainer-associated misalignment cases.

METHODS

This pilot study is based on a retrospective data analysis. Adult patients (age 25.5 ± 4.9 years) wearing fixed twistflex retainers and having visible retainer-associated misalignment were included and examined for tooth movement after retainer debonding. Orthodontic study models were taken at retainer debonding (t0) and 14 (±1) weeks later (t1). They were digitally superimposed using 2D/3D dental imaging software and tooth movement was analyzed in all three dimensions.

RESULTS

A total of 23 teeth (12 upper teeth: 10 incisors, 2 canines; 11 lower teeth: 7 incisors, 4 canines) were analyzed. Mean overall tipping was 1.11 ± 0.82° in the mesial/distal direction (angulation, x‑axis), 2.02 ± 1.9° in the buccal/lingual direction (inclination, y‑axis) and 1.28 ± 0.99° around the tooth axis (z-axis). Mean overall bodily movement was 0.30 ± 0.31 mm in the mesial/distal direction (angulation, x‑axis), 0.10 ± 0.13 mm in the buccal/lingual direction (inclination, y‑axis), and mean in- or extrusion 0.22 ± 0.24 mm (z-axis). Mean tipping and bodily movement were more pronounced in the upper jaw.

CONCLUSION

The present data shows that tooth movement after debonding of twistflex retainers can be expected in misalignment cases.

The effects of fixed orthodontic retainers on periodontal health: A systematic review

INTRODUCTION

The objective of this systematic review was to assess the available evidence in the literature for the effects of fixed orthodontic retainers on periodontal health.

METHODS

The following databases were searched up to August 31, 2019: Medline, EMBASE, the Cochrane Oral Health Group's Trials Register, CENTRAL, ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. Randomized controlled trials (RCTs), controlled clinical trials, cohort studies of prospective and retrospective design, and cross-sectional studies reporting on periodontal measurements of patients who received fixed retention after orthodontic treatment were eligible for inclusion. The quality of the included RCTs was assessed per the revised Cochrane risk of bias tool for randomized trials (RoB 2.0), whereas the risk of bias of the included cohort studies was assessed using the Risk Of Bias In Nonrandomized Studies of Interventions tool. A modified version of the Newcastle-Ottawa scale was used for cross-sectional studies.

RESULTS

Eleven RCTs, 4 prospective cohort studies, 1 retrospective cohort study, and 13 cross-sectional studies fulfilled the inclusion criteria. The quality of evidence was low for most of the included studies. In contrast to the general consensus, 2 RCTs, 1 prospective cohort study, and 2 cross-sectional studies reported poorer periodontal conditions in the presence of a fixed retainer. The results of the included studies comparing different types of fixed retainers were heterogeneous.

CONCLUSIONS

According to the currently available literature, orthodontic fixed retainers seem to be a retention strategy rather compatible with periodontal health, or at least not related to severe detrimental effects on the periodontium.

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.

Comparison of Stability of the Results of Orthodontic Treatment and Gingival Health between Hawley and Vacuum-formed Retainers

Aim: Retention is one of the stages of orthodontic treatment, which is an attempt to retain teeth in their corrected positions after active treatment with the use of fixed orthodontic appliances. The aim of the present study was to compare the stability of the results of orthodontic treatment and the gingival health between Hawley retainer (HR) and vacuum-formed retainer (VFR) with two different thicknesses. Materials and methods: In this randomized clinical trial, 66 patients undergoing comprehensive orthodontic treatment in a private office were evaluated after completion of treatment. The subjects were randomly assigned to three groups. At the end of orthodontic treatment, the subjects in all the groups received a fixed bonded retainer in the mandible; in the maxilla, group I received an HR, group II received a VFR with a thickness of 1.5 mm, and group III received a VFR with a thickness of 1 mm. The American Board of Orthodontics objective grading system (ABO-OGS) index was used at the end of treatment (before the delivery of the retainers) and 6 months after the use of retainers to evaluate the stability of the results of orthodontic treatment. Gingival index (GI) was used at the two above-mentioned intervals to evaluate gingival health. The ABO-OGS measurements were carried out on dental casts by a clinician who was blinded to the types of retainers the patients wore. Data were analyzed with Statistical Package for the Social Sciences (SPSS) version 20, using proper statistical analyses. Results: Six months after the delivery of retainers, ABO-OGS and GI scores with the 1.5 mm VFR were higher than those in the two other groups, with no significant differences between the three groups. There were no significant differences between the ABO-OGS scores before the delivery of retainers and 6 months after the use of retainers in any of the study groups. In the HR and 1.5 mm VFR groups, there were significant differences in GI scores between the period before the delivery of the retainers and 6 months after their delivery; however, in the 1 mm VFR group, no significant differences were observed in GI scores between the two time intervals. Conclusion: Hawley retainer and 1 mm thick and 1.5 mm thick VFRs were equally effective in preserving and stabilizing the results of orthodontic treatment during the 6-month interval after the completion of orthodontic treatment. In addition, there were no significant differences between the three retainers in relation to gingival health. Clinical significance: The VFR might be a good alternative for HR due to its better esthetic appearance and greater popularity with orthodontic patients. Keywords: American Board of Orthodontics model grading system, American Board of Orthodontics objective frading system, Gingival index, Hawley retainers, Vacuum-formed retainers.

Gingival condition associated with two types of orthodontic fixed retainers: a meta-analysis

Background

The maintenance of gingival health around orthodontic fixed retainers (FRs) is difficult and different designs have been proposed.

Objective

The goal of this systematic review was to analyse whether FR designs that allow unobstructed interproximal flossing, compared with the ones that do not, improve gingival parameters.

Search methods

Detailed individual database search strategies for Cochrane Library, 'Latin' American and 'Caribbean' Health Sciences Literature, PubMed, Scopus, and Web of Science were developed. Grey literature was also considered.

Selection criteria

Clinical trials and cross-sectional studies that compared two types of FRs (plain and waved) were included and evaluated.

Data collection and analysis

Study selection, data extraction, and risk of bias (RoB) assessment were performed individually and in duplicate. The methodology quality was assessed using the MAStARI RoB tool.

Results

Four studies met the inclusion criteria, and all presented moderate RoB. While two of those studies found a statistically significant difference in gingival parameters, the other two did not report differences. A meta-analysis was conducted based on two of the selected studies, which performed evaluations of plaque index (PI) and calculus index (CI). The results revealed no differences on PI between wave FR and plain FR of 0.46 (0.24 to 0.69) and no differences on CI of 0.12 (-0.10 to 0.33). Regarding comfort, no clear differences were identified.

Conclusions

There is not enough scientific evidence to support or not an association between FR design and gingival health, flossing frequency, or patient comfort.

Registration

PROSPERO - CRD42016030059.

Effects of different orthodontic retention protocols on the periodontal health of mandibular incisors

OBJECTIVES

To test the following two hypotheses: 1) different types of retainers result in distinct levels of biomarkers in gingival crevicular fluid (GCF) and 2) the retainer bonded to all mandibular anterior teeth induces more detrimental outcomes to the periodontium.

SETTING AND SAMPLE POPULATION

The Department of Orthodontics at the University of Florida. The population consisted of individuals in the retention phase of orthodontic treatment.

MATERIAL AND METHODS

This was a cross-sectional study that enrolled 36 individuals. Subjects in group 1 had retainers bonded to the mandibular canines only. Group 2 consisted of individuals having retainers bonded to all mandibular anterior teeth. Group 3 included patients using mandibular removable retainers. After clinical examination, GCF was collected from the mandibular incisor and biomarker levels were compared between the groups.

RESULTS

Plaque accumulation and gingivitis differed significantly among groups, with the highest median values in group 2 subjects. Pairwise comparison of the groups with respect to gingivitis showed significant differences between groups 1 and 2. Significant differences among groups were detected for RANKL, OPG, OPN, M-CSF, MMP-3, and MMP-9. The ratio RANKL/OPG was significantly higher in group 2 subjects, with pairwise comparisons indicating that groups 1 and 2 differed from group 3.

CONCLUSION

An association was found between orthodontic retention groups and GCF biomarker levels, which should be further explored in longitudinal studies. The presence of retainers bonded to all anterior teeth seems to increase plaque accumulation and gingivitis.

The effects of fixed and removable orthodontic retainers: a systematic review

OBJECTIVE

In the view of the widespread acceptance of indefinite retention, it is important to determine the effects of fixed and removable orthodontic retainers on periodontal health, survival and failure rates of retainers, cost-effectiveness, and impact of orthodontic retainers on patient-reported outcomes.

METHODS

A comprehensive literature search was undertaken based on a defined electronic and gray literature search strategy (

PROSPERO

CRD42015029169). The following databases were searched (up to October 2015); MEDLINE via OVID, PubMed, the Cochrane Central Register of Controlled Trials, LILACS, BBO, ClinicalTrials.gov, the National Research Register, and ProQuest Dissertation and Thesis database. Randomized and non-randomized controlled clinical trials, prospective cohort studies, and case series (minimum sample size of 20) with minimum follow-up periods of 6 months reporting periodontal health, survival and failure rates of retainers, cost-effectiveness, and impact of orthodontic retainers on patient-reported outcomes were identified. The Cochrane Collaboration's Risk of Bias tool and Newcastle-Ottawa Scale were used to assess the quality of included trials.

RESULTS

Twenty-four studies were identified, 18 randomized controlled trials and 6 prospective cohort studies. Of these, only 16 were deemed to be of high quality. Meta-analysis was unfeasible due to considerable clinical heterogeneity and variations in outcome measures. The mean failure risk for mandibular stainless steel fixed retainers bonded from canine to canine was 0.29 (95 % confidence interval [CI] 0.26, 0.33) and for those bonded to canines only was 0.25 (95 % CI: 0.16, 0.33). A meta-regression suggested that failure of fixed stainless steel mandibular retainers was not directly related to the period elapsed since placement (P = 0.938).

CONCLUSION

Further well-designed prospective studies are needed to elucidate the benefits and potential harms associated with orthodontic retainers.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial

OBJECTIVE

Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers.

METHODS

In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05).

RESULTS

In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146).

CONCLUSIONS

Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.