An in vitro comparison of the dimensional stability of four 3D-printed models under various storage conditions

OBJECTIVES

To investigate the dimensional stability of various 3D-printed models derived from resin and plant-based, biodegradable plastics (PLA) under specific storage conditions for a period of up to 21 weeks.

MATERIALS AND METHODS

Four different printing materials, including Draft V2, study model 2, and Ortho model OD01 resins as well as PLA mineral, were evaluated over a 21-week period. Eighty 3D-printed models were divided equally into two groups, with one group stored in darkness and the other exposed to daylight. All models were stored at a constant room temperature (20°C). Measurements were taken at 7-week intervals using the Inspect 3D module in OnyxCeph software (Image Instruments GmbH, Chemnitz, Germany).

RESULTS

Dimensional change was noted for all of the models with shrinkage of up to 0.26 mm over the study period. Most contraction occured from baseline to T1, although significant further contraction also arose from T1 to T2 (P < .001) and T1 to T3 (P < .001). More shrinkage was observed when exposed to daylight overall and for each resin type (P < .01). The least shrinkage was noted with Ortho model OD01 resin (0.16 mm, SD = 0.06), and the highest level of shrinkage was observed for Draft V2 resin (0.23 mm, SD = 0.06; P < .001).

CONCLUSIONS

Shrinkage of 3D-printed models is pervasive, arising regardless of the material used (PLA or resin) and being independent of the brand or storage conditions. Consequently, immediate utilization of 3D printing for orthodontic appliance purposes may be preferable, with prolonged storage risking the manufacture of inaccurate orthodontic retainers and appliances.

Elemental composition, corrosion resistance and mechanical properties of computer-aided design and computer-aided manufacturing fixed retainers versus conventional fixed retainers

PURPOSE

To investigate the elemental composition, corrosion resistance, and mechanical properties of computer-aided design and computer-aided manufacturing (CAD-CAM) retainers versus conventional fixed retainers (FRs).

METHODS

Eight different retainer wires were investigated. Energy dispersive X-ray spectroscopy was used to determine the elemental composition. Leakage was analysed according to ISO 10271:2020 guidelines. Hardness was tested using the Vickers method with a load of 0.3 kg. The tensile force and tensile strength were evaluated. Multiple comparisons among wires of hardness, tensile force, and strength were conducted using the Welch t-test, with Bonferroni correction.

RESULTS

Nickel was present in all wires. The CAD-CAM-FR wire, which contained more nickel than the other wires, had no measurable leakage. The gold-plated wires had the highest total leakage, but did not exceed the ISO standard limit. The hardness of the stainless-steel twisted wires was the highest and that of the CAD-CAM-FR wire was the lowest. The tensile strength of the CAD-CAM-FR wire was significantly lower than that of the other wires and similar to the other twisted-wire retainers.

CONCLUSION

The CAD-CAM-FR wire is likely to have high corrosion resistance and flexibility due to its low hardness.

Stability, survival, patient satisfaction, and cost-minimization of CAD/CAM versus conventional multistranded fixed retainers in orthodontic patients: a 2-year follow-up of a two-centre randomized controlled trial

BACKGROUND

CAD/CAM (computer-aided design/computer-aided manufacturing) fixed retainers (FRs) as an alternative to multistranded FRs to maintain orthodontic treatment outcome.

OBJECTIVES

The primary aim was to compare CAD/CAM versus conventional multistranded FRs in terms of stability until 2 years. Secondary outcomes were failure rates, patient satisfaction, and cost-minimization.

TRIAL DESIGN

2-arm parallel, two-centre randomized controlled trial.

METHODS

Patients were randomized to CAD/CAM or conventional FRs in both arches, in a 1:1 ratio and blocks of four. Allocation concealment was secured by using sequentially numbered envelopes. Patients were blinded. FRs were bonded at the end of treatment, and patients were recalled after 12 and 24 months. First-time retainer failures were recorded and digital impressions were taken. Arch widths and lengths, as well as Little's Irregularity Index (LII), were measured. Additionally, patients answered satisfaction questionnaires. Linear mixed models were applied for measurements and patient satisfaction. Survival analyses were estimated with Kaplan-Meier curves, along with Cox-regression modelling. Cost-minimization analysis was undertaken.

RESULTS

One hundred and eighty-one patients were randomized (98 in Centre 1, and 83 in Centre 2): 90 in CAD/CAM and 91 in conventional group. One hundred and fifty three patients attended T24 follow-up. There were no significant differences in LII and arch dimensions between groups for failure-free patients. Within 24 months, 34% maxillary CAD/CAM FRs and 38% maxillary conventional FRs failed, along with 42% mandibular CAD/CAM FRs and 40% mandibular conventional FRs, with no significant difference in survival between groups (hazard ratios conventional to CAD/CAM: maxillary arch: 1.20 [P = 0.46], mandibular arch: 0.98 [P = 0.94]). There were no significant differences in patient satisfaction between groups. No harms were observed. Cost-minimization analysis showed that CAD/CAM FRs were slightly cheaper than conventional FRs.

CONCLUSIONS

There were no clinically significant differences in LII, arch widths, and lengths between CAD/CAM and conventional FRs after 24 months. There were no differences in failures and patient satisfaction between groups. CAD/CAM FRs were slightly cheaper than conventional FRs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04389879.

Stability and failure rate during 3 years of fixed retention: A follow-up of an randomized clinical trial on adolescents with four different lingual retainers

OBJECTIVE

To evaluate stability outcomes and failure rates associated with four types of lingual retainers: (1) dead-soft wire, (2) multistrand stainless steel (SS) wire, (3) CAD/CAM nitinol, and (4) connected bonding pads (CBPs) after 3 years of retention.

METHODS

This study enrolled 96 patients (66 females, 30 males) with a median age of 19 years with four types of lingual retainers: (1) 0.016 × 0.022-inch dead-soft wire, (2) 0.0215-inch five-strand SS wire, (3) 0.014 × 0.014-inch CAD/CAM nitinol wire, and (4) CBPs. The irregularity index, intercanine distances, and arch lengths were obtained and used to evaluate mandibular stability. Failure rates were also assessed during this study. Data were statistically analysed.

RESULTS

Irregularity increased, whereas intercanine width and arch length decreased after 3 years of retention. The greatest irregularity was associated with the CBPs and the least with the CAD/CAM retainers. Changes in stability measurements were significantly higher in the dead-soft wire and CBPs than those in the CAD/CAM nitinol and multistrand SS wires. Parallel to these changes, the frequency of failure yielded similar results with the same significance between the groups. The failure rate of CBPs, in contrast to the CAD/CAM nitinol and multistrand SS wires, was significantly higher in the right quadrant (P < .05).

CONCLUSION

After taking the 3-year results into consideration, CAD/CAM nitinol and multistrand SS wires were found to be more successful than the others in maintaining mandibular stability. The most failures were observed with CBPs after 3 years of retention.

Environmental sustainability of post-orthodontic dental retainers: a comparative life-cycle assessment of Hawley and Essix retainers

BACKGROUND

Environmental sustainability has been brought into the limelight due to the global climate crisis. This crisis is driven by human activities and even the healthcare sector is no exception. Within dentistry, orthodontics is a large global market; hence, the use of post-orthodontic retainers has a significant environmental footprint. The aim of this study was to determine the environmental sustainability of post-orthodontic retention using Hawley and Essix retainers.

MATERIALS AND METHODS

A comparative life-cycle assessment (LCA) was carried out to compare the environmental impact of both retainers. All inputs and outputs were accounted for using the Ecoinvent database, v3.7.1, and openLCA software. Sixteen impact categories were used to determine their environmental burden.

RESULTS

Of the 16 impact categories, the Hawley had a greater environmental burden than the Essix retainer in 12 categories. The Hawley's most significant contributors to its impact values are factory manufacturing and in-house production, with an average of 41.45% and 52.52%, respectively. For the Essix, the greatest contributor is factory manufacturing, with an average of 64.63%. However, when factoring in the lifespan of the retainers, the Essix would have a greater environmental impact than the Hawley retainer.

LIMITATIONS

This study employed a comparative LCA. There were also assumptions made, but these were supported by research.

CONCLUSIONS

On the basis of the evidence gathered in this study, Hawley retainers are more environmentally sustainable than Essix retainers. These results would better enable clinicians to factor in the environmental impact and make informed decisions on the choice of retainer type.

Impact of fixed orthodontic retainers on oral health-related quality of life: a longitudinal prospective study

OBJECTIVE

The aim of the present study was to assess the impact of orthodontic retainers on oral health-related quality of life (OHRQoL) in the short and long terms after orthodontic treatment.

METHODS

Data from 45 patients up to three years after orthodontic treatment (T0) were analyzed. Patients were reassessed four years (T1) after T0. OHRQoL was measured using the OHIP-14 (Oral Health Impact Profile-14) questionnaire. The presence of a fixed retainer in the upper and/or lower arches, sex, and age were the predictive variables evaluated at T0 and T1. The occurrence of retainer fracture at T0 was clinically evaluated. Due to the COVID-19 pandemic, clinical examination on T1 was not possible, so the OHIP-14 and the self-perception of changes in teeth position and fracture of retainers were examined using an on-line questionnaire.

RESULTS

At the initial examination, the presence of upper retainers had a negative impact on quality of life (p=0.018). The OHIP-14 value increased significantly from T0 to T1 (p=0.014), regardless of the presence of retainers. The fracture or debonding of the retainer reported by the patient was the only variable that had a negative impact on OHRQoL (p=0.05).

CONCLUSION

The use of fixed upper retainers suggests a negative impact on the quality of life of the orthodontic patient after the end of orthodontic treatment. This impact, however, is negligible in the long term, except when associated with fracture or debonding. This study emphasizes the need for continuous follow-up of orthodontic patients during the retention period.

Orthodontic Retainers and the Stability of the Maxillary Arch in Unilateral Cleft lip and Palate Patients: A Systematic Review

OBJECTIVE

The aim of this systematic review was to elucidate the role of orthodontic retainers on the stability of compensatory orthodontic treatment in patients with unilateral cleft lip and palate.

METHODS

Five electronic databases (PubMed, Scopus, Web of Science, LILACS, and LIVIVO) and the grey literature (OpenGrey and Google Scholar) were investigated, according to the population, exposure, comparator, outcomes and Study design eligibility criterion. The risk of bias assessment was determined based on the Risk of Bias In Nonrandomized Studies of Exposure (ROBINS-E) and the level of evidence with the GRADE tool.

RESULTS

Three studies were included: two presented moderate risk of bias and one high. A moderate level of evidence revealed a mean value of 0.6 mm of intercanine relapse distance, and great variability between the data, regardless of the use or type of retention or rehabilitation. Relapse in the posterior region showed clinical significance, from -1 to -1.7 mm, especially in individuals who did not use retention, except in patients with symmetrical arches with Hawley retainer, where this value varies from -0.2 ± 0.63 mm.

CONCLUSIONS

Orthodontic retainers do not seem essential to prevent relapse at anterior maxillary dimensions after compensatory orthodontic treatment in patients with unilateral cleft lip and palate. Relapse in the posterior region can achieve greater clinical significance, which highlights the need for prolonged use of Hawley retainers and periodic evaluation of the stability of treatment results. Prospective studies with a longer follow-up can improve the certainty of the evidence.

Comparison of efficacy of thermoplastic retainer with round and rectangular bonded lingual wire retainer in the mandible two years after orthodontic treatment: a randomised controlled trial

OBJECTIVE

To analyse three protocols in maintaining the stability of orthodontic therapy results and their effect on gingival health.

MATERIALS AND METHODS

Sixty-six subjects (pre-therapeutic age 11-18 years; 68% female) randomly allocated into three retention groups of equal size were analysed. The first group had a 0.673 × 0.268 mm (0.027 × 0.011 inches) rectangular braided steel retention wire bonded to the lingual surfaces of all mandibular teeth from canine to canine, and the second group had a 0.406 mm (0.016 inches) round twisted steel wire. The third group was the control, without wires, and only with vacuum-formed retainers. All three groups had vacuum-formed removable retainers in the maxilla. The frequency of wire detachment/breakage/loss of retainer, the occurrence of crowding of mandibular incisors, and changes in intercanine width and gingival health were monitored.

RESULTS

Incidence and severity of relapse differed between groups (p = 0.001 and 0.049) being most common in the removable retainer group (incidence 68.2%; severity 0.7 ± 1.0 mm), followed by the round wire group (36.4%; 0.5 ± 1.2 mm) and rectangular wire group (13.6%; 0.1 ± 0.1 mm). The intercanine width decreased more without a bonded retainer (incidence 68.2%; severity 0.5 ± 0.7 mm) and with the round wire more (45.5%; 0.5 ± 0.7 mm) than with the rectangular (27.3%; 0.1 ± 0.3 mm). The difference was significant for incidence (p = 0.025), but not severity. Detaching of the wires/breakage/loss of retainer was similar. There were no significant differences in the accumulation of biofilm, calculus and gingivitis between appliances.

CONCLUSION

A rectangular wire is the most effective in retention, and the impact of retention appliances on gingival health is similar.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05121220. Registered 02 October 2021 - Retrospectively registered.

CLINICAL RELEVANCE

Studying guidelines for reducing relapse, proper use of materials and appliances, the behavior of retention wires according to their profile in the retention phase, and possibilities of maintaining oral health will contribute to improving the stability of orthodontic therapy results.

Masticatory muscle activity and oral health-related quality of life in patients wearing clear thermoplastic versus wrap-around retainers : A randomized controlled trial

AIM

To evaluate the surface electromyography (sEMG) activity of the superficial masseter and anterior temporalis muscles at rest, during maximum voluntary clenching (MVC), and mastication, over 6 months of wearing clear thermoplastic or wrap-around retainers. Furthermore, the patients' oral health-related quality of life was assessed using the Oral Impacts on Daily Performance (OIDP) index at 6 months.

MATERIALS AND METHODS

Sixty patients aged 14-39 years (19 males/41 females) who received upper and lower retainers after finishing orthodontic treatment were recruited. The patients were randomly divided into a clear thermoplastic retainer group (n = 30) or a wrap-around retainer group (n = 30). The sEMG activity was recorded at retainer delivery (T0), after 3 months (T1), and after 6 months of wearing (T2). The OIDP index was evaluated at T2.

RESULTS

None of the sEMG parameters for the masseter and temporalis muscles were different between the two groups at T0, T1, or T2. Over the period of 6 months, both masticatory muscles in both groups demonstrated increased sEMG activity during MVC and mastication; however, only the temporalis muscle demonstrated decreased normalized sEMG activity at rest (P < 0.05). The frequency and severity of the OIDP in the eating aspect at T2 was low and similar in both groups.

CONCLUSIONS

sEMG activity of the two masticatory muscles tended to increase during MVC and mastication, while temporalis muscle activity tended to decrease at rest during the observation period, regardless of retainer type. Notably, these sEMG changes did not affect the patients' subjective masticatory function.

Relapse and failure rates between CAD/CAM and conventional fixed retainers: a 2-year follow-up of a randomized controlled clinical trial

BACKGROUND

Retention has been always considered a major challenge in orthodontics. Recently computer-aided design/computer-aided manufacturing (CAD/CAM) fixed retainers (FRs) have been introduced as a marked development in retainer technology, offering potential advantages.

OBJECTIVE

The objective of this study was to compare the differences in relapse and failure rates in patients treated with FRs using CAD/CAM technology, lab-based technique, and chairside method.

TRIAL DESIGN

A double-blinded, prospective, randomized controlled clinical trial was conducted over a 2-year period at a single centre.

METHODS

INTERVENTIONS

These patients were divided into three groups: CAD/CAM group with multistranded Stainless Steel wires (CAD/CAM, n = 14), lab group with the same multistranded wires (lab, n = 15), and a chairside group with Stainless Steel Ortho-FlexTech wires (chairside, n = 14).

OUTCOMES

Inter-canine width (ICW) and Little's irregularity index were digitally measured from scans at the orthodontic debonding (T1), 6-month retention (T2), 1-year retention (T3), and 2-year retention (T4) visits. All forms of failure were documented and analyzed.

RANDOMIZATION

Participants were randomly assigned to the three groups using online randomization software (randomization.com) by a statistician who was not involved in the study.

BLINDING

Patients were blinded in terms of the FR group to which they were each randomly assigned. The principal investigator was blinded upon data analysis since patients' records were coded to minimize observer and measurement bias.

RESULTS

Initially 81 patients were assessed for eligibility. Seventy-five patients were randomly allocated into the three study groups. After 2-year follow-up, 43 patients came back for the follow-up and were analyzed. The CAD/CAM group showed significantly less reduction in ICW compared to the chairside group at all time intervals (P < .05) and compared to the lab group at 6 months (P = .038). In terms of LII, the CAD/CAM group exhibited significantly less change than the chairside and lab groups at all time intervals (P < .05). The CAD/CAM group had the lowest failure rate (21.4%), followed by chairside group (28.6%) and then lab group (33.3%), however the differences were insignificant. No harms were observed in the current study.

CONCLUSION

Within 2 years of fixed retention, CAD/CAM FRs showed significantly less relapse than lab-based and chairside FRs. However, there was no significant difference in failure rates among the groups.

TRIAL REGISTRATION

NCT05915273.

Mechanical properties of materials for 3D printed orthodontic retainers

AIM

The purpose of this study was to compare the mechanical properties of materials used for orthodontic retainers made by direct 3D printing and thermoforming.

The prevalence of the failure of fixed orthodontic bonded retainers: a systematic review and meta-analysis

OBJECTIVES

To systematically assess the scientific literature for the prevalence of failure rate of fixed orthodontic bonded retainer (FOBR).

METHOD

Randomized clinical trials (RCTs) and prospective non-RCTs involving participants who had FOBR fitted were included. The Cochrane Central Register of Controlled Trials, Web of science, MEDLINE, and EMBASE via OVID were searched from inception to January 2023. Risk of bias was assessed using the Cochrane RoB 2 and Newcastle-Ottawa tools. The main outcome was the failure rate of FOBRs. The secondary outcome was to identify factors that can influence the failure of FOBR. Meta-analyses and sensitivity analyses were undertaken using Revman, version5.4. A random-effects model was used. Quality assessment using Grading of Recommendations Assessment, Development, and Evaluation.

RESULTS

Thirty-four studies (25 RCTs and 9 prospective clinical studies) (3484 participants) were included in this review. The overall failure rate of bonded retainers, after excluding high-risk studies, was 35.22% (95% confidence interval [CI] 27.46-42.98). The failure rate is increased with the duration of follow up; with short-term follow-up rate 24.18% (95% CI 20.16-28.21), medium-term follow up 40.09% (95% CI 30.92-49.26), and long-term follow up 53.85% (95% CI 40.31-67.39). There is a low level of evidence to suggest there is no statistically significant difference in the failure rate of fixed retainers using direct versus indirect bonding methods, using liquid resin versus without liquid resin, and fibre-reinforced composite retainers compared to multi-stranded stainless steel retainers.

DISCUSSION

There is low-quality evidence to suggest that the failure rate of FOBR is relatively high. There is a need for high-quality, well-reported clinical studies to assess factors that can influence the failure rate of FOBR.

REGISTRATION

CRD42021190910.

Stability of maxillary anterior teeth during retention and 1 year after removal of retention-an RCT on adolescents retained with two different bonded retainers and a vacuum-formed retainer

BACKGROUND

Maxillary bonded and removable retainers maintain teeth in correct positions following orthodontic treatment. There is insufficient evidence regarding the capacity of the retention methods to stabilize the maxillary teeth both during and after retention.

OBJECTIVE

To evaluate retention capacity and 1-year post-retention changes in the irregularity of maxillary anterior teeth and single anterior tooth contact point discrepancy (CPD) of two bonded and one removable retention method.

TRIAL DESIGN

Three-arm parallel group single-centre randomized controlled trial.

METHODS

Ninety adolescent patients treated with fixed orthodontic appliances were enrolled. After gaining informed consent, the patients were randomized in blocks of 30 by an independent person into one of three groups: A) bonded retainer 13-23; B) bonded retainer 12-22; and C) removable vacuum-formed retainer. The primary outcomes were changes in Little's irregularity index (LII) and single CPD measured on digitalized casts before retention (T1), after 2 years of retention (T2), and 1-year post-retention (T3).

BLINDING

The digital casts were blinded for the outcome assessor.

RESULTS

Data on all 90 patients were analysed according to intention-to-treat principles. Changes in LII during retention were 0.3 mm in group A, 0.6 mm in group B, and 1.0 mm in group C. No significant differences between the groups were seen (P > 0.05). Changes during post-retention were 1.1 mm in group A, 0.5 mm in group B, and 0.4 mm in group C. Group A showed more significant changes than groups B and C (P = 0.003). During the whole post-treatment period, no significant differences were shown between the groups (P > 0.05). CPD did not differ significantly between the groups at any point.

HARMS

Three patients showed changes of LII over 3 mm or CPD over 2 mm during the post-retention period, and two accepted to be realigned.

LIMITATIONS

The trial was a single-centre study evaluating 1-year post-retention changes.

CONCLUSIONS

The changes were clinically insignificant during and after the retention period. Thus, all three methods showed equal retention capacity.

TRIAL REGISTRATION

www.clinicaltrials.com (NCT04616755).

Effects of three orthodontic retainers on periodontal pathogens and periodontal parameters

The objective of this study was to compare and evaluate the changes in periodontal pathogens and periodontal status within 6 months of wearing three orthodontic retainers, namely, vacuum-formed retainer (VFR), Hawley retainer (HR), and lingual fixed retainer (LR). In total, 48 patients who underwent orthodontic treatment with ordinary metal brackets were divided into VFR, HR, and LR groups (n = 16 per group). Saliva samples were collected at the time of debonding (T0) and after 1 month (T1), 3 months (T2), and 6 months (T3). Porphyromonas gingivalis (Pg) and Aggregatibacter actinomycetemcomitans (Aa) were quantitatively analyzed using real-time PCR. Gingival index (GI), plaque index (PLI), and probing depth (PD) were measured at the four time points to evaluate changes in periodontal state. SPSS20.0 software was used to analyze the data, and P < 0.05 was considered statistically significant. The trial was registered at the Chinese Clinical Trial Registry (ChiCTR2300073704), the registration was retrospective. Compared to baseline (T0) values, Pg, Aa, GI, PLI, and PD were significantly decreased in all three groups 1 month after wearing the retainer (p < 0.05). Significant differences were observed in Aa at T3 among the three groups, whereby the HR group exhibited significantly better results compared to the VFR and LR groups (p < 0.05). Differences were found among the three groups' Porphyromonas gingivalis at T3, and the HR group was significantly better than the VFR and LR groups (P < 0.05). From T1 to T2, GI, PLI, and PD of the three groups tended to be stable, however differences were observed at T3, with the PLI and PD of the HR group being the lowest among the three groups (p < 0.05). Regardless of the type of retainer used, the periodontal condition of patients was significantly improved after removal of the metal brackets. After 6 months of retainer use, the Hawley retainer was superior to vacuum-formed retainer and lingual fixed retainer with regard to Pg, Aa, and periodontal clinical parameters.

An assessment of the impact of adhesive coverage and wire type on fixed retainer failures and force propagation along two types of orthodontic retainer wires: an in vitro study

OBJECTIVES

To evaluate the force required to promote the failure of fixed orthodontic retainers with different adhesive (composite) coverage and to assess the presence and extent of force propagation with two different orthodontic retainer wires.

MATERIALS AND METHODS

Ortho-FlexTech and Ortho-Care Perform (0.0175 inches), each of 15-cm length, were bonded on acrylic blocks with different adhesive surface diameters (2 mm, 3 mm, 4 mm, and 5 mm). The samples (n = 160) were subjected to a tensile pull-out test, and debonding force was recorded. Fixed retainers using two different wires and 4-mm adhesive diameter were bonded on acrylic bases resembling a maxillary dental arch (n = 72). The retainers were loaded occluso-apically until the first sign of failure while being video recorded. Individual frames of the recordings were extracted and compared. A force propagation scoring index was developed to quantify the extent of force transmission under load.

RESULTS

A 4-mm adhesive surface diameter required the highest debonding force for both retainer wires with significant differences compared with 2 mm (P < .001; 95% confidence interval [CI]: 8.69, 21.69) and 3 mm (P = .026; 95% CI: 0.60, 13.59). Force propagation scores were significantly higher for Ortho-Care Perform.

CONCLUSIONS

Based on this laboratory-based assessment, consideration should be given to the fabrication of maxillary fixed retainers using a minimum of 4-mm diameter composite coverage on each tooth. Force appeared to propagate more readily with Ortho-Care Perform than with a flexible chain alternative. This may risk stress accumulation at the terminal ends with potential for associated unwanted tooth movement in the presence of intact fixed retainers.

Effect of the quality of orthodontic finishing on the stability of anterior tooth alignment

OBJECTIVES

To evaluate whether the quality of orthodontic finishing influences long-term stability of anterior tooth alignment.

MATERIALS AND METHODS

This retrospective study evaluated 38 patients. Data were obtained at the beginning of treatment (T0), at the end (T1), and at least 5 years after T1 (T2). At this point, the individuals were no longer wearing retainers. Anterior tooth alignment was measured using Little's index (LI). Effect on alignment stability was tested with multiple linear regression using LI-T0, LI-T1, intercanine width difference T1-T0, overbite (T1), overjet (T1), age, gender, time without retention, and presence of third molars as predictor variables. Well-aligned (LI < 1.5 mm) and misaligned (LI > 1.5 mm) cases were compared at T2.

RESULTS

At T2, the alignment stability in the upper arch was inversely associated with the alignment quality (R2 = 0.378, P < .001) and directly associated with overbite (R2 = 0.113, P = .008) at T1. Posttreatment changes caused cases finished with poor alignment to become similar to those finished with excellent alignment (P = .917). In the mandible, posttreatment changes were directly associated only with overjet (R2 = 0.152, P = .015) and well-finished cases displayed better alignment than poorly finished cases (P = .011). Other variables showed no significant association.

CONCLUSIONS

In arches without retention, better quality of orthodontic finishing does not guarantee the stability of anterior alignment. In the maxilla, long-term changes were more significant the greater the overbite and the better the quality of alignment at end of treatment. In the mandible, changes were not dependent on the quality of finishing but were associated with greater overbite at T2.

A comparative evaluation of mechanical wear of adhesives used for bonded retainers that underwent brushing for 1 hour under 36 mm of linear action, using computer-aided 3D scan-an in vitro study

OBJECTIVES

The aim of the present study was to comparatively evaluate the mechanical wear of adhesives used in bonded retainers.

MATERIALS AND METHODS

Eighty mandibular acrylic teeth were included in the study that were divided into 4 different groups based upon the composite used. Each acrylic tooth was bonded with a retainer wire and composite of their respective group (Heliosit, Restofill, Tetric-N-flow, and Filtek Z350 XT). These bonded acrylic teeth were subjected to 3D scan in order to evaluate the volume and surface area of the composite. The 3D scans were recorded using MEDIT 3D scanner. After evaluating, the samples were subjected to brushing with the aid of a custom-made brushing simulator using a toothbrush with soft bristles and toothpaste slurry. The samples were subjected to 1 hr of brushing. These samples were again subjected to 3D scans to evaluate (post-test volume and surface area) and underwent statistical analysis.

RESULTS

The results showed the Heliosit group exhibited the highest mean volume (1.76 mm3) and surface area (4.81 mm2) difference between the pre-test and post-test values whereas the least mean volume difference (1.10 mm3) and surface area difference (3.21 mm2) were seen in the Tetric-N-flow group.

CONCLUSION

All the four composites underwent change in the mean surface area and volume after being subjected to brushing, suggesting that the composites routinely used for bonding fixed bonded lingual retainers are subjected to changes due to abrasion. The Heliosit group, which showed least filler loading among the 4 composites, exhibited least resistance to wear, whereas the Tetric-N-flow group which had highest filler loading among the composites exhibited highest resistance to wear.

CLINICAL RELEVANCE

The most crucial phase during orthodontic treatment is the retention phase. This phase is responsible for the long-term results of the treatment. The retainers that are placed in the oral cavity are subjected to changes due to oral environment, chemical changes, and mechanical changes. These changes have a direct effect on the retainers, which tend to alter their properties. Thus, the effects of these changes are to be studied thoroughly.

Evaluation of orthodontic retention and retainer content on the Reddit social media website

BACKGROUND

Social media can provide insight into patient experiences with health care. The aim of this study was to evaluate the content regarding orthodontic retention and retainers on the social media website, Reddit.

METHODS

A systematic search for relevant content submitted over a 12-month period on the Reddit forum, r/braces, was conducted. Qualitative analysis of the initial posts for themes and subthemes was conducted by two investigators. Responding comments to the initial posts were assessed for supportiveness for each initial poster and alignment with the evidence-base. Quantitative assessment was via descriptive statistics.

RESULTS

A total of 271 initial posts and 984 comments satisfied the inclusion/exclusion criteria. All initial posts were by patients. Just 1.12% (n = 11) of the comments appeared to be provided by oral health professionals. Most initial posts were negative (50.18%; n = 136), and most comments were positive (70.42%; n = 693). Alignment with the evidence-base was high among the comments (67.89%; n = 668). Eight main themes were identified with concerns regarding the negative impact of retention and retainers on quality of life, compliance with retention protocols and relapse commonly expressed. Concern regarding fear of relapse when waiting for the initial or renewal of retainers was a novel finding. More negative sentiments about orthodontists were expressed than positive.

CONCLUSIONS

Reddit is a supportive and reliable environment for patients regarding orthodontic retention and retainers. The content evaluation suggested deficiencies in communication processes between clinicians and patients. Greater engagement of the orthodontic profession in the provision of supportive and evidence-based information on an individual patient basis and through appropriate information channels is required.

A comparison of CAD/CAM-based fixed retainers versus conventional fixed retainers in orthodontic patients: a systematic review and network meta-analysis

OBJECTIVE

Comparing computer-aided design and computer-aided manufacturing (CAD/CAM) fixed retainers and conventional fixed retainers for their effectiveness in orthodontic patients using systematic review and meta-analysis of literature.

SEARCH METHODS

A comprehensive search was conducted in MEDLINE, Web of Science, EMBASE, Scopus, Cochrane's CENTRAL, Google Scholar, Ovid, and LILACS up to May 2023, with no language or date restrictions.

SELECTION CRITERIA

Only randomized clinical trials (RCTs) that complied with PICO questions were included, and the Cochrane Risk of Bias 2.0 (RoB 2) tool was used to assess the risk of bias in the included studies.

DATA COLLECTION AND ANALYSIS

Using custom-piloted forms, relevant data were retrieved from the included studies. Then a random-effects inverse variance meta-analysis was used to pool the results. Primary outcomes were stability of treatment results measured through dental cast measurements and periodontal status, while secondary outcomes were failure rates and patient-reported outcomes.

RESULTS

Seven RCTs with 601 participants were included in the review. In the short term (≤6 months), the meta-analysis showed no significant differences in inter-canine distance or arch length between CAD/CAM and conventional fixed retainers in mandibular retainers. However, for Little's irregularity index, single-stranded stainless-steel retainers were notably worse than Ni-Ti CAD/CAM retainers at 3 and 6 months, while multi-stranded stainless-steel retainers only diverged from CAD/CAM at the 6-month milestone, despite the overall clinical inconsequence of these changes. CAD/CAM retainers were associated with a lower plaque index than traditional retainers but no significant difference in gingival index. Failure rates did not differ significantly between CAD/CAM and other types of retainers in mandibular retainers. Nonetheless, one study had a high amount of CAD/CAM retainer failures leading to the study being stopped.

CONCLUSIONS

In the short term, CAD/CAM fixed retainers show promise as an alternative to traditional retainers. They may enhance periodontal health, as indicated by lower plaque index scores than conventional retainers. However, extensive research is needed to determine the long-term durability and effectiveness of CAD/CAM retainers in orthodontic treatment, particularly regarding their failure rate. Until comprehensive evidence is available, the use of CAD/CAM retainers should be tailored for each case.

REGISTRATION

The protocol for this systematic review was registered at PROSPERO with the ID CRD42023412741.

Assessment of the effectiveness of two different orthodontic retention protocols

INTRODUCTION

The main goal of orthodontic retention is to keep the teeth in their corrected positions. Fixed or removable retainers are the most common types of retainers used during the retention phase. For the maxilla, various types of retainers have been described, including the vacuum-formed retainers and Hawley retainers. Fixed retainers are used for the lower jaw.

Diagnostic compatibility of various fixed orthodontic retainers for head/neck MRI and dental MRI

OBJECTIVES

To evaluate the diagnostic MRI compatibility of different fixed orthodontic retainers using a high-resolution 3D-sequence optimized for artifact reduction.

MATERIALS AND METHODS

Maxillary and mandibular retainers made of five different materials were scanned in vitro and in vivo at 3 T MRI using an MSVAT-SPACE sequence. In vitro, artifact volumes were determined for all maxillary and mandibular retainers (AVmax; AVmand). In vivo, two independent observers quantified the extent of artifacts based on the visibility of 124 dental and non-dental landmarks using a five-point rating scale (1 = excellent, 2 = good, 3 = acceptable, 4 = poor, 5 = not visible).

RESULTS

Rectangular-steel retainers caused the largest artifacts (AVmax/AVmand: 18,060/15,879 mm3) and considerable diagnostic impairment in vivo (mean landmark visibility score ± SD inside/outside the retainer areas: 4.8 ± 0.8/2.9 ± 1.6). Smaller, but diagnostically relevant artifacts were observed for twistflex steel retainers (437/6317 mm3, 3.1 ± 1.7/1.3 ± 0.7). All retainers made of precious-alloy materials produced only very small artifact volumes (titanium grade 1: 70/46 mm3, titanium grade 5: 47/35 mm3, gold: 23/21 mm3) without any impact on image quality in vivo (each retainer: visibility scores of 1.0 ± 0.0 for all landmarks inside and outside the retainer areas).

CONCLUSIONS

In contrast to steel retainers, titanium and gold retainers are fully compatible for both head/neck and dental MRI when using MSVAT-SPACE.

CLINICAL RELEVANCE

This study demonstrates that titanium and gold retainers do not impair the diagnostic quality of head/neck and dental MRI when applying an appropriate artifact-reduction technique. Steel retainers, however, are not suitable for dental MRI and can severely impair image quality in head/neck MRI of the oral cavity.

Effect of bonded and removable retainers on occlusal settling after orthodontic treatment: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to summarize the effectiveness of bonded and removable retainers (the Hawley and Essix retainers) in terms of improving occlusal settling (occlusal contact points/areas) after orthodontic treatment. We searched the Cochrane Library, PubMed, CINAHL Plus, and Dental & Oral Sciences Source (DOSS), as well as SIGLE, Google Scholar and ClinicalTrials.gov for eligible studies. We included randomized and non-randomized controlled trials along with cohort studies. Studies that reported occlusal contacts/areas during retention with fixed bonded and removable retainers were included. To assess the quality of the randomized controlled trials (RCTs), the Cochrane Collaboration risk-of-bias (RoB) tool was utilized, whereas the Newcastle-Ottawa Scale (NOS) was used to assess the quality of cohort studies.We included 6 articles in our systematic review after scrutinizing 219 articles and eliminating the illegible ones based on duplication, titles, abstracts, and objectives. Bonded retainers (BRs) allowed faster and better posterior occlusal settling as compared to the Hawley retainer (HR). However, HR showed good occlusal settling in the anterior dental arch. The Essix retainer (ER) showed a decrease in occlusal contact during the retention phase. Meta-analysis showed no statistically significant difference between BRs and removable retainers. In conclusion, HR allowed better overall occlusal settling as compared to other retainers. However, BRs allowed faster settling in the posterior tooth region. The Essix retainer showed poor settling of occlusion. Overall, there is an insufficient number of high-quality RCTs to provide additional evidence, and further high-quality RCTs are needed.

FIBER REINFORCED COMPOSITE RETAINERS MAY BE AS EFFECTIVE AS MULTISTRANDED STAINLESS-STEEL WIRES IN FAILURE RATES AND MINIMAL ADVERSE EFFECT, BUT SUPERIOR IN TERMS OF RELAPSE AND PATIENT SATISFACTION

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Liu S, Silikas N, Ei-Angbawi A. Analysis of the effectiveness of the fiber-reinforced composite lingual retainer: A systematic review and meta-analysis. Am J Orthod Dentofacial Orthop. 2022 Aug 26:S0889-5406(22)00,432-2. doi: 10.1016/j.ajodo.2022.07.003. Epub ahead of print. PMID: 36,031,511.

SOURCE OF FUNDING

Not reported.

TYPE OF STUDY/DESIGN

Systematic review with meta-analysis of data.

Comparison of microleakage and shear bond strength of ribbon and twisted wire retainers bonded on human mandibular incisors with two different types of adhesives with and without primer: An in-vitro study

BACKGROUND AND OBJECTIVES

Shear bond strength and microleakage are the success factors of fixed retainers. Recently, primer-free composites were introduced to reduce chair time. The main objectives of this study were to compare the shear bond strength (SBS) and microleakage of GC Ortho Connect^TM Flow (OF) and Transbond^TM XT (TXT) with two types of common retainer wires (0.0175-inch twisted wire and 0.028×.0.008-inch ribbon dead soft wire retainers). The secondary objectives of the study were to compare enamel-adhesive interface and wire-adhesive interface microleakages.

MATERIALS AND METHODS

This in vitro study was conducted on 132 human mandibular incisors (96 for bond strength and 36 for microleakage). The teeth were randomly divided into four groups for use of ribbon and twisted wires with OF and TXT adhesives. The bond strength was measured by a universal testing machine. Microleakage was evaluated by the dye penetration test using 0.05% fuchsine. Data were analysed by two-way ANOVA (alpha=0.05).

RESULTS

No significant difference was noted in bond strength among the four groups (P>0.05). However, the microleakage of OF was significantly higher than that of TXT at both the enamel-adhesive and wire-adhesive interfaces (P<0.001). The microleakage at the wire-adhesive and enamel-adhesive interface was not significantly different in groups 1 and 4 and was significant in group 2 and 3.

CONCLUSION

Type of adhesive significantly affected the microleakage, and OF resulted in higher microleakage than TXT at both the enamel-adhesive and wire-adhesive interfaces. Type of wire had no significant effect on microleakage. Although OF showed comparable SBS to TXT, its higher microleakage may compromise its successful long-term clinical service.

Mechanical Properties of 3D Printed Orthodontic Retainers

Orthodontic retention is the final important stage of orthodontic treatment, the aim of which is to consolidate the functional and aesthetic position of teeth. Among adults, fixed retainers made of different types of wires are the most common. The aim of this study was to analyse the mechanical properties of a new generation of fixed orthodontic retainers-printed by 3D printers.

MATERIALS AND METHODS

The study was conducted using samples made of Nextdent MFH C&B N1 resin in the form of cuboid bars with nominal dimensions of width b = 3 mm, thickness d = 0.8 mm; 1 mm; 1.2 mm, length l = 30 mm for each type. The influence of the thickness of the retainers on their strength under loaded conditions was evaluated. Flexural strength, elastic properties, deflection, and creep were compared. The samples were aged in an artificial saliva bath at 37 ± 1 °C during the strength tests.

RESULTS

It was shown that differences in the thickness of the samples affected their elastic and strength properties. The highest average flexural modulus, the highest deflection, creep, and strength was characteristic of the samples with the highest thickness (1.2 mm). Samples with an average thickness of 1 mm had the lowest modulus of elasticity.

CONCLUSIONS

The mechanical properties of 3D printed retainers show that they can be an alternative to metal retainers and the procedure of making new retainers, especially when patients have aesthetic requirements or allergies to metals.

A Comparative Assessment of Three Mandibular Retention Protocols: A Prospective Cohort Study

PURPOSE

Fixed retainers have been advocated for the prevention of anterior mandibular crowding after orthodontic treatment. However, limited data is available to help clinicians choose a retention protocol that is acceptable in terms of stability, emergencies, and side effects in the long term. It was the aim of this study to assess survival and alignment stability of the 0.016" x 0.022" stainless steel wire compared to more common protocols.

MATERIALS AND METHODS

Three different mandibular fixed retention protocols were compared in 600 consecutive patients: 1. 0.0215" multistrand wire (MW) with separate curing of resin and composite; 2. 0.016" x 0.022" stainless-steel wire with simultaneous curing of resin and composite (SS1C); and 3. 0.016" x 0.022" stainless-steel wire with separate curing of resin and composite (SS2C). The hazard rate for detachment across wire groups was assessed with a Cox frailty model.

RESULTS

Incisor alignment was maintained with all retention wires. One incisor with unexpected torque change was observed in group MW. The average annual emergency rate was below 2% for all three protocols. Fewer emergency visits were found in patients with solid steel wires than with multistrand wires. Detachment of the wire is the most common cause of emergency visits with no difference between wire types. Multistrand wires were more often damaged than were solid steel wires. There was no evidence that direct application of the composite on the uncured primer influenced retainer adhesion to the enamel.

CONCLUSIONS

The mandibular anterior teeth can be predictably stabilised with a 0.016" x 0.022" stainless steel wire..

Evaluation of relapse with thermoplastic retainers equipped with microsensors

OBJECTIVES

To examine relapse with thermoplastic retainers equipped with microsensors 1 year after treatment.

MATERIALS AND METHODS

A total of 42 patients (29 females, 13 males) treated with four premolar extractions were included in this study. Thermoplastic appliances equipped with TheraMon microsensors (Handelsagentur Gschladt, Hargelsberg, Austria) were used to assess daily wear time (DWT), and the patients were monitored at 2-month intervals for a period of 12 months. At the end of the follow-up, the following two groups were formed based on the mean DWT: short wear time (SWT; <9 h/d) and long wear time (LWT; ≥9 h/d). Digital models were constructed before treatment (T0), at debonding (T1), and 6 months (T2) and 12 months (T3) after debonding. Little's Irregularity Index (LII) and the intercanine and intermolar widths, arch lengths, overjet, and overbite were calculated based on the digital models. Data were analyzed statistically.

RESULTS

Irregularity and overjet increased, whereas transverse measurements and arch lengths decreased with time in both groups. During the retention period, overbite decreased in the SWT group but increased in the LWT group. There were significant differences between groups only in mandibular irregularity. The LII values of the SWT group were significantly higher than those of the LWT group for the T1-T2 and T1-T3 time intervals (P < .05).

CONCLUSIONS

A mean DWT less than 9 hours/day was inadequate for controlling irregularity within clinically acceptable limits. A wear time of at least 9 h/d is recommended for the maintenance of mandibular anterior alignment.

Comparative assessment of relapse and failure between CAD/CAM stainless steel and standard stainless steel fixed retainers in orthodontic retention patients

OBJECTIVES

To compare relapse and failure rates of computer-aided design/computer-aided manufacturing (CAD/CAM) and standard fixed retainers.

MATERIALS AND METHODS

This single-center, single-blinded, prospective randomized clinical trial included 46 patients who completed active orthodontic treatment and complied with retention visits. The patients were randomly assigned to three groups: CAD/CAM group with multistranded stainless steel wires (CAD/CAM, n = 16), Lab group with the same multistranded wires (lab, n = 16), and control group with stainless steel Ortho-FlexTech wires (traditional, n = 14). Intraoral scans were obtained at placement of fixed retainers (T1), 3-month visit (T2), and 6-month visit (T3) and measured for intercanine width and Little's Irregularity Index. Failures were recorded.

RESULTS

The CAD/CAM group experienced less intercanine width decrease than the traditional group at 3 months (mean difference, 0.83 ± 0.16 mm; 95% confidence interval [CI], 0.44-1.22; P < .001) and 6 months (mean difference, 1.23 ± 0.40 mm; 95% CI, 0.19-2.27; P < .05). The CAD/CAM group experienced less increase in Little's Irregularity Index compared with the lab group within 3 months (mean difference, 0.81 ± 0.27 mm; 95% CI, 0.12-1.49; P < .05). Failures from greatest to least were experienced by the lab group (43.8%), the CAD/CAM group (25%), and the traditional group (14.3%).

CONCLUSIONS

Within 6 months of bonding fixed retainers, CAD/CAM fixed retainers showed less relapse than lab-based and traditional chairside retainers and less failures than lab-based retainers.

Three-dimensional analysis of the posttreatment displacements of mandibular anterior teeth with rigid and flexible lingual retainers

INTRODUCTION

The purpose of this study was to analyze any posttreatment changes in the positions of mandibular anterior teeth retained by 2 different fixed retention methods (rigid or flexible) and their effectiveness in minimizing postorthodontic tooth movement.

METHODS

Thirty patients were selected for inclusion in this retrospective study. Group I consisted of 15 patients with 0.032-in stainless steel rigid retainers bonded to canines only. Group II consisted of 15 patients with 0.0215-in twisted stainless steel flexible retainer bonded to all mandibular anterior teeth. Geomagic Control (3DS Systems, Rock Hill, SC) software was used to quantify the changes between selected points. Paired t test was used for intragroup comparisons in all 3 coordinates, and an independent-sample t test was used for intergroup comparison.

RESULTS

In the transverse dimension, significant intergroup differences were found in displacements of distoincisal points of the right lateral (P <0.05) and left central incisors (P <0.01). In the sagittal dimension, significant intergroup differences were found in the displacements of mesioincisal point of the right central incisor (P <0.05) and distoincisal point of the left central incisor (P <0.01). Examining total displacement, there were significant intergroup differences in mesioincisal point on the right central incisor, distoincisal point on the left lateral incisor (P <0.05).

CONCLUSIONS

Our results suggested that central incisor contacts were more likely to shift with the rigid retainers, especially in sagittal and transverse dimensions. However, no statistically or clinically significant changes were noted in the third-order or vertical positions of the teeth with either retention method.

One-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers

OBJECTIVES

To compare the clinical effectiveness of Hawley retainers (HRs) and modified vacuum-formed retainers (mVFRs) with palatal coverage in maintaining transverse expansion during a 12-month retention period.

MATERIALS AND METHODS

Data were collected from postorthodontic treatment patients who met the inclusion criteria. A total of 35 patients were randomly allocated using a centralized randomization technique into either mVFR (n = 18) or HR group (n = 17). The outcome assessor and data analyst were blinded to the retention method. Dental casts of patients were evaluated at debond, 3 months, 6 months, and 12 months of retention. Intercanine width (ICW), interpremolar width (IPMW), interfirst molar mesiobuccal cusp width 1 (IFMW1), and interfirst molar distobuccal cusp width 2 (IFMW2) were compared between groups over time using mixed analysis of variance.

RESULTS

No statistically significant differences were found between the two groups for ICW (P = .76), IPMW (P = .63), IFMW1 (P = .16), and IFMW2 (P = .40) during the 12-month retention period.

CONCLUSIONS

The null hypothesis could not be rejected. HR and mVFR had similar clinical effectiveness in the retention of transverse expansion cases during a 12-month retention period.

Anterior openbite malocclusion in adults: Treatment stability and patient satisfaction in National Dental Practice-Based Research Network patients

OBJECTIVES

To investigate stability and satisfaction in adult anterior open bite (AOB) patients at least 9 months post-treatment, as well as patient and practitioner factors that may be associated with stability and satisfaction.

MATERIALS AND METHODS

Practitioners and their adult AOB patients were recruited through the National Dental Practice-Based Research Network. Data on patient and practitioner characteristics, treatment recommendations and factors were previously collected. Treatment stability was determined by assessing post-treatment intraoral photographs. Patient satisfaction was determined from post-treatment questionnaires. Treatment was categorized into aligners, fixed appliances, temporary anchorage devices, and orthognathic surgery. Extractions were also investigated. Retention type was categorized into vacuum-formed, Hawley-style, or bonded retainers, and regimens were classified as full-time or part-time wear.

RESULTS

Retention data collected from 112 patients had a mean post-treatment time of 1.21 years. There were no statistically significant differences in stability between treatment groups. Depending on whether a qualitative index or a millimetric measure was employed, stability ranged from 65% to 89%. Extractions and less initial lower incisor proclination were associated with higher stability in patients treated with fixed appliances only. High satisfaction was reported by patients at retention. There were no clear differences in stability or satisfaction among retention types or regimens.

CONCLUSIONS

The stability of adult AOB orthodontic treatment was high, regardless of treatment or retainer modality. Satisfaction in adult AOB patients was high, regardless of retention type or regimen.

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.

Transfer accuracy of four different lingual retainer transfer methods using digital orthodontic models: An in vivo comparative study

OBJECTIVES

To compare the transfer accuracy of four different lingual retainer (LR) transfer methods using three-dimensional digital models.

MATERIALS AND METHODS

Four groups of 17 patients each were created: finger transfer (FT), silicone key transfer (SKT), acrylic resin transfer (ART), and indirect bonding (IDB). At the end of orthodontic treatment, the mandibular dental casts of patients were scanned with the LR wire. Then, intraoral scanning of the mandibular arches was performed after bonding the retainer wires. Linear and angular measurements were made using software on superimposed digital models.

RESULTS

Horizontal and vertical errors among the teeth were not significantly different among the FT, SKT, and ART groups. However, in the IDB group, linear transfer errors showed significant differences among the different teeth. The tip and rotation errors in the FT group were not significantly different among the teeth. The angular errors were lower in canines than in the incisors. In all measured parameters, the SKT group showed the lowest errors, whereas the FT group had the highest transfer errors in all parameters except vertical.

CONCLUSIONS

Among the transfer methods tested, SKT was determined to have the highest clinical accuracy.

Effects of different lingual retainers on periodontal health and stability

OBJECTIVES

To evaluate the effects of different lingual retainers on periodontal health and stability of mandibular anterior teeth at the 1-year follow-up.

MATERIALS AND METHODS

One hundred thirty-two patients were randomly allocated to four groups using different lingual retainers: group 1, 0.016 × 0.022-in dead-soft wire; group 2, 0.0215-in 5-strand stainless steel wire; group 3, 0.014 × 0.014-in computer-aided design/computer-aided manufacturing nitinol retainer (Memotain); group 4, connected bonding pads. Plaque, gingival, and calculus indexes were used to evaluate periodontal health, and Little's irregularity index, intercanine width, and arch length measurements were performed to evaluate stability. All measurements were performed at each time point (debonding and 3, 6, 9, and 12 months).

RESULTS

The mean value of the gingival index obtained in group 3 was lower than the mean value for all other groups. The mean value of the calculus index was the lowest in group 3, and there was a significant difference between group 3 and groups 1 and 2. No differences were found among the groups in terms of plaque index, intercanine width, and arch length. The least irregularity was obtained in groups 2 and 3. There were no significant differences between these groups and groups 1 and 4.

CONCLUSIONS

Gingival inflammation and calculus accumulation were the lowest in group 3 (Memotain). The irregularity for Memotain and stainless steel retainers was less than or the other groups. However, no clinically significant worsening of periodontal health or relapse were seen in any groups after 1 year.

Orthodontic retention: what's on the horizon?

Orthodontic retention remains one of the great challenges in orthodontics. In this article, we discuss what is on the horizon to help address this challenge, including biological approaches to reduce relapse, treating patients without using retainers, technological developments, personalised medicine and the impact of COVID-19 on approaches to orthodontic retention.

Physiological and Immunological Changes Associated with Oral Microbiota When Using a Thermoplastic Retainer

Background: The study examined the oral microbiota, physiological and immunological changes in patients using thermoplastic retainers during three months of use. Methods: The study included several steps. Firstly, 10 swabs were collected from the buccal and palatal surfaces of the teeth of the patients, approximately 2 mL of saliva was collected from the same patients and 2 mL of saliva was collected from 10 healthy people to measure the pH and secretory IgA level. This was followed by the isolation and identfication of the bacterial isolates in the patient samples. Then, isolate susceptibility toward chlorhexidine (CHX) and their adhesion ability to thermoplastic retainer surfaces was measured. In addition to that the study estimated the numbers of Lactobacillus and Streptooccus mutans colonies during three months and finally, a comparsion of pH acidity and IgA level between the patients and healthy people was performed. The results showed the predominant bacteria during the three months were Lactobacillus spp. and Streptococcus spp. followed by different rates of other bacteria. Raoultella ornithinolytica showed more resistance to CHX while Lactobacillus spp. showed more sensitivity. Streptococcus mutans colony levels were higher than Lactobacillus spp. colonies during the three months, also S. mutans had the highest value in adherence to retainer thermoplastic. Finally, pH acidity showed a highly significant difference (p ≤ 0.05) in the third month, like IgA levels (p ≤ 0.05). Conclusions: According to the results obtained from the current study, the researchers noted that the thermoplastic retainers helped change the oral cavity environment.

An Audit of Orthodontic Retention Protocol in a Tertiary Health Institution: A 3-Year Retrospective Study

BACKGROUND

The aim of this study was to determine the retention practices following orthodontic treatment in a tertiary health institution in Nigeria.

METHODS

A retrospective study conducted in the Orthodontic Clinic of the Lagos University Teaching Hospital over a 3-year-period. Data on the type of retainers used and the retention practices in the upper and lower arches were obtained from case files of patients who had completed orthodontic treatment in the institution. Statistical analysis was performed using IBM SPSS software version 23.

RESULTS

The demographic variables comprised of 136 subjects; 93 females (68.4%) and 43 males (31.6%). Their ages ranged from 9-44 years with a mean age of 18.96 ± 6.75. Class I malocclusion was the most common malocclusion pattern (84.6%), followed by Class II (10.3%) and Class III (5.1%). Removable retainers were more commonly used and accounted for retention carried out in 85.3% of the study population. There was a preference for the use of removable retainers in the upper arch; the Hawley retainer being the most used (79.4%). In the lower arch however, no form of retention was carried out for majority of the patients after orthodontic treatment (86.8%). However, when done, the fixed lingual retainer was the most frequently used (13.2%).

CONCLUSION

The Hawley retainer was the predominant retainer in this study. The fixed lingual retainer was the most frequently used in the lower arch. Longitudinal studies are required to determine efficacy of different types of retention following orthodontic treatment.

Fixed Orthodontic Retainers Do Not Seem to Adversely Affect Periodontal Health

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

The effects of fixed orthodontic retainers on periodontal health: A systematic review. Arn M, Dristas K, Pandis N, Kloukos D. Am J Orthod Dentofacial Orthop 2020;157:156-64.

SOURCE OF FUNDING

Information is not available and the authors did state any specific funding for this study and report no potential conflicts of interest.

TYPE OF STUDY/DESIGN

Systematic review.

[Factors playing a part in the failure of retention wires]

Retention plays an important part during orthodontic treatment. Orthodontic treatment can be divided into 2 phases: an active phase in which treatment is carried out with orthodontic appliances and a second, passive phase with retention, with which an attempt is made to prevent a return to the original or another position. In practice, fixed retainers with a retention wire are usually chosen because of the many advantages of such wires. Even though fixed retention is now the gold standard in orthodontic follow-up, it does fail fairly often. In particular, because the procedures for manufacturing and placing are technically sensitive. A number of studies report that on average 34.9% (range of 10.3-47%) of the bonded retention wires come loose after an average of 2 years. A number of factors play a part in this. Based on the literature, it is possible to make some practical recommendations on the lifespan of a retainer.

Long-term Effectiveness of Maxillary and Mandibular Bonded Orthodontic Retainers

PURPOSE

This retrospective cohort study investigated the long-term effectiveness of one type of maxillary and 2 types of mandibular fixed lingual retainers.

MATERIALS AND METHODS

Eighty orthodontic patients in retention for 10-15 years were included. Irregularity index, intercanine width, overjet (OJ) and overbite (OB) were measured on plaster models at 3 occasions: (T1) pre-treatment, (T2) post-treatment and (T3) 10-15 years post-treatment. Analyses assessed the effect of the retainer type and time on mandibular irregularity, intercanine width and retainer failure.

RESULTS

In the mandible, the irregularity index increased (0.43 mm) between T2 and T3 for the 0.027" β-titanium (TMA) retainers bonded to canines only while it was stable (-0.02 mm) for the 0.016" x 0.022" braided stainless steel retainers (SS6) bonded to all six anterior teeth. The intercanine width was relatively stable in both groups during the entire observation period. In the maxilla, the irregularity index was stable between T2 and T3 (+0.07 mm). The intercanine width increased (+2.02 mm) during treatment T1-T2 and was stable (-0.02 mm) in the retention phase T2 to T3.

CONCLUSIONS

In the mandible, SS6 retainers were slightly more effective in maintaining alignment compared to the TMA retainers. In the maxilla, the SS4 retainers without canine extensions were effective in maintaining alignment. All retainers were effective in maintaining the intercanine width.

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.

Lower fixed retainers: bonded on all teeth or only on canines? A systematic review

OBJECTIVE

To evaluate the stability after orthodontic treatment between two types of lower fixed retainers: those bonded onto all anterior teeth or those bonded only onto the canines.

MATERIALS AND METHODS

The following electronic databases were consulted: PubMed, Scopus, Web of Science, Cochrane Library, Lilacs, OpenGrey, ClinicalTrials, and Google Scholar. No restriction of language or year were applied. After selection of studies, risk-of-bias evaluation and qualitative synthesis of the included studies were performed using The Cochrane Collaboration's tool for randomized studies and the "Risk of Bias in Non-randomized Studies of Interventions" (ROBINS-I) tool for nonrandomized studies, and a summary of the overall strength of evidence was presented using the "Grading of recommendations, assessment, development and evaluation" tool.

RESULTS

Among the 180 studies retrieved from the searches, five were included in this review. Three of them showed a low risk of bias, while two presented a high risk of bias. With regard to stability, two studies reported better stability for retainers bonded to all six teeth, while the other three showed no difference. The retainer bonded to all teeth presented a higher breakage rate in one study.

CONCLUSIONS

Stability seems better with lower fixed retainers bonded on all anterior teeth. The breakage rate may not change according to the bonding. However, studies with greater methodological soundness are necessary to reach a more reliable conclusion.

Level of satisfaction in the use of the wraparound Hawley and thermoplastic maxillary retainers

OBJECTIVE

To compare the level of satisfaction in the use of wraparound Hawley and thermoplastic maxillary retainers.

MATERIALS AND METHODS

The study sample included 70 orthodontic patients (24 males and 46 females), who were in the retention stage (mean age = 20.80 years). All patients wore the two types of maxillary retainer for 1 month each, along with a 3×3 fixed mandibular retainer. After the use of each retainer, the patients responded to a questionnaire evaluating the level of satisfaction with their use of the maxillary retainer. Intergroup comparison was performed by independent t tests. Chi-square test was used to evaluate preference for the type of retainer by gender.

RESULTS

The thermoplastic retainer was better for swallowing and the wraparound Hawley appliance was better for hygiene and durability. The other factors evaluated (adaptation, speech, comfort, esthetics, satisfaction, and fitting) did not show significant differences between the retainers. There was also no significant difference in preference for the appliances.

CONCLUSIONS

Regarding the overall satisfaction and the preference, there was no difference between the wraparound Hawley and thermoplastic retainers. The wraparound Hawley appliance was better in hygiene and resistance than the thermoplastic retainer; and the thermoplastic appliance was better than the wraparound Hawley for swallowing fluids and saliva.

Orthodontic Retainers: A Contemporary Overview

AIM

The aim of this article is to provide an insight into the various modalities of retention and types of appliance used in achieving this objective.

BACKGROUND

Maintaining the orthodontically treated teeth in their corrected position is a challenging and ominous task since the inception of this specialty. Orthodontic retainers play a pivotal role in preventing posttreatment tooth movement, thereby maintaining the esthetic, function, and stability of the stomatognathic system.

RESULTS

An extensive study of literature suggests that there are significant variations in the results describing the effectiveness, cost factors, survival times, oral hygiene status, and regimen of various orthodontic retention appliances. In terms of patient's satisfaction and speech articulation, vacuum-formed retainers (VFRs) are better than Hawley retainers. Occlusal contacts are better achieved with Hawley retainers than VFRs.

CONCLUSION

Currently, there is insufficient high-quality evidence in favor of a particular retention appliance/regime or protocol. There is a need for further evidence-based high-quality studies/randomize controlled trial studies (RCTs) to evaluate different orthodontic retention appliances and regime after the orthodontic treatment.

CLINICAL SIGNIFICANCE

Irrespective of the appliance, the patients should be prepared for a long-term or indefinite retention phase following orthodontic treatment to prevent relapse.

[Treatment of class II for growing patients by clear aligners: which protocol?]

INTRODUCTION

Skeletal class II, frequently associated with retromandibular and overjet > 2 mm, lead to functional and aesthetic damage, that orthodontic treatment has to correct. The aim of this article is to describe a treatment protocol by aligners for class II growing patients according to the value of the class II and the maturity state of cervical vertebrae.

MATERIALS AND METHODS

Through clinical cases, this article will present three different therapeutic approaches depending on the growth state.

RESULTS

The study of the auxologic potential and determination of the bone age (radiological analysis of the maturation of the cervical vertebrae) will allow to determine the best moment to treat class II and the most appropriate therapeutic attitude according to growing state.

DISCUSSION

This study before treatment is essential to adapt an individualized clinical protocol to each patient. In this way, aligners are devices that respond well to this imperative because they are customizable in view of the strategy and the treatment plan considered by the practitioner. We must keep in mind, however, that with any therapy, it is essential to ensure good patient compliance.