A multi-center randomized controlled trial to compare a self-ligating bracket with a conventional bracket in a UK population: Part 1: Treatment efficiency

Development and Evaluation of a New Orthodontic Ligature: Frictional Force Analysis

OBJECTIVE

 To evaluate and compare the friction of different ligature modes used in orthodontics, and to propose a new ligature model for conventional brackets ("H low-friction orthodontic ligature).

MATERIALS AND METHODS

 Samples were randomly divided into seven experimental groups: (1) resin H ligature (H3D), designed by the authors of this study and produced in a 3D printer, with conventional bracket; (2) metal H ligature (HFM), with conventional bracket; (3) passive self-ligating bracket (SLP); (4) "8" low-friction unconventional elastic (LT8), with conventional bracket; (5) loose conventional metal ligature (MLS), with conventional bracket; (6) conventional metal ligature fully tightened (MLT), with conventional bracket; (7) conventional elastic ligature (CEL), with conventional bracket-control. All samples were subjected to mechanical static friction testing using the EMIC DL 2000 universal testing machine.

STATISTICAL ANALYSIS

 To assess the normality requirement, the Shapiro-Wilk test was used, which showed a non-normal distribution for the means of the groups (p < 0.05). Therefore, statistical tests were performed to assess the existence of statistically significant differences between the groups through the Kruskal-Wallis, followed by Dunn's test, pairwise comparison, p < 0.05.

RESULTS

 The results obtained showed lower friction values for HFM (0.002 kgf), SLP (0.003 kgf), and LT8 (0.004 kgf)-these did not differ statistically from each other. These were followed by H3D (0.020 kgf), MLS (0.049 kgf), CEL (0.12 kgf), and, finally, MLT (0.21 kgf).

CONCLUSION

 The lowest friction value was found for the metal H ligature, similar to the self-ligating bracket and the "8" low-friction unconventional elastic. The resin H ligature presented intermediate friction values and the highest friction force was found for the MLT group.

Comparative assessment of dental and basal arch dimensions of passive and active self-ligating versus conventional appliances : A randomized clinical trial

PURPOSE

In this parallel, three-arm, single-center randomized trial, the dental and basal arch dimensions after orthodontic treatment using conventional brackets and passive and active self-ligating (SL) brackets were compared.

METHODS

Patients needing comprehensive orthodontic treatment were randomly allocated to the active SL, passive SL, or conventional brackets (control) group. All patients were treated with a standardized arch wires sequence. Eligibility criteria included class I malocclusion in the permanent dentition, crowding (4-6 mm), and adequate oral hygiene. The primary outcome was intermolar width, based on cone beam computed tomography (CBCT) scans. Secondary outcomes were maxillary and mandibular widths in the canines and premolars regions, dental arch depth, buccolingual inclination, and alignment duration. Blinding of outcome assessment was implemented. Patients were followed every 4 weeks until insertion of the stainless steel 0.019 × 0.025 wire. Mean values were computed from CBCT sections, and data were analyzed using a one-way analysis of variance.

RESULTS

In all, 66 patients (ages 18-25 years) were randomized into a 1:1:1 ratio; 7 patients dropped out before treatment initiation. Examining dental arch dimensions in the canine and premolar regions showed that expansion of the maxillary dental arch was greatest in the passive SL brackets group, less in the active SL brackets group, and lowest in the control group (P < 0.01). Changes in maxillary intermolar width between the three groups were not significant, and changes in basal arch dimensions, depth of dental and basal arches, buccolingual inclination, and alignment duration were similar in the three groups.

CONCLUSIONS

Self-ligating brackets were not more effective than conventional brackets when examining intermolar width, basal transverse dimensions, depth of the arch, and alignment duration.

Is there any difference between conventional, passive and active self-ligating brackets? A systematic review and network meta-analysis

AIM

To test the null hypothesis that there was no difference in treatment efficiency between therapies undertaken with conventional (CBs), passive self-ligating (PSLBs) or active self-ligating (ASLBs) brackets.

MATERIALS AND METHODS

An electronic search was performed in 3 data bases (Pubmed, Web of Science, Cochrane Library) from their origin up to January 2019. Additional references were hand searched. Search was strictly restricted to randomized controlled trials (RCTs) and split-mouth design studies (SMDs). RCTs and SMDs were initially processed separately and subsequently combined in a network meta-analysis. The following variables were evaluated: treatment duration, number of visits, occlusal outcomes, alignment rate, transverse arch dimensional changes, incisor position modification, rate of space closure, anchorage loss, bond failure, root resorption, perception of discomfort during the initial phase of alignment, time to ligate in or to untie an archwire, periodontal variables, quality of life.

RESULTS

On 229 papers, 30 RCTs and 9 SMDs were finally included in this study. Out of 85 comparisons, 16 only revealed statistically significant differences. It was quicker to untie and ligate an 0.014 NiTi arch from/in 6 ASLBs anterior ceramic brackets compared to 6 ceramic CBs. It was also more painful to insert and remove an 0.019×0.025 SS wire in/from PSLB's brackets compared to CB's attachments. Compared to conventional brackets, there was less maxillary incisor proclination with PSLBs in non-extraction cases. Moreover, there was less bleeding on probing 4-5 weeks after bonding with PSLBs compared to CBs brackets. The only significant difference between ASLBs and PSLBs was that alignment was 10 days faster with active self-ligating braces compared with passive self-ligating braces even if treatment duration between ASLBs and PSLBs was not significantly different. The network meta-analysis revealed that IMPA was greater in extractions cases with CBs compared with both ASLBs (+2,5°) and PSLBs (+1,6°).

CONCLUSIONS

The vast majority of the studied variables did not show any significant differences between the three types of brackets. The most significant findings were that it was quicker to insert and remove archwires from ASLBs compared to CBs, and it was more painful to insert and remove an 0.019×0.025" stainless steel wire in/from PSLBs compared to CBs. The major difference between ASLBs and PSLBs was that alignment was 10 days faster with active self-ligating braces compared with passive self-ligating braces even if treatment duration between ASLBs and PSLBs was not significantly different. Most of the claims put forward by the suppliers were not substantiated by our network meta-analysis.

The Influence of Friction on Design of the Type of Bracket and Its Relation to OHRQoL in Patients Who Use Multi-Bracket Appliances: A Randomized Clinical Trial

Background and objectives: The aim of this study was to evaluate the influence of friction on design of the type of bracket, patients’ perception of pain and the impact on their oral health-related quality of life. Materials and Methods: A randomized clinical trial was carried out with 90 patients (62.2% women and 37.8% men) with three kinds of fixed multi-bracket appliances: Conventional (GC), fixed multi-bracket low friction (GS) and self-ligating (GA). The VAS (Visual Analogue Scale) was used to determine pain during the first seven days of treatment at different points in time. The patients were also given the OHIP-14 (Oral Health Impact Profile) questionnaire to analyse their oral health-related quality of life (OHRQoL) after the first 30 days of treatment. The ANOVA test was used for the analysis of the variables and the post hoc Bonferroni test for the comparison between groups. Results: Maximum pain was observed between one and two days after the start of treatment. The GC group showed the greatest degree of pain, with maximum values (4.5 ± 2.0) at 24 h. The self-ligation brackets show lower impact on patients’ oral health-related quality of life (0.8 ± 2.2, p < 0.01). Conclusions: Friction in the type of bracket influences pain and the Oral Health-Related Quality of Life of patients who use multi-bracket fixed orthodontics.

Analysing the potential of hydrophilic adhesive systems to optimise orthodontic bracket rebonding

Introduction

Bond failure during fixed orthodontic treatment is a frequently occurring problem. As bracket rebonding is associated with reduced shear bond strength, the aim of the present investigation is to analyse the effect of different innovative rebonding systems to identify optimised rebonding protocols for orthodontic patient care.

Methods

Metallic brackets were bonded to the frontal enamel surfaces of 240 bovine lower incisors embedded in resin bases. Teeth were randomly divided into two major experimental groups: in group 1 a hydrophilic primer (Assure™ PLUS) was compared to commonly used orthodontic adhesives (Transbond XT™, BrackFix®, Grengloo™) and a zero control. In group 2 different rebonding systems were analysed using a hydrophilic primer (Assure™ PLUS), a methyl methacrylate-consisting primer (Plastic Conditioner) and a conventional adhesive (Transbond XT™). All teeth were tested for shear bond strength according to the DIN-13990 standard, the Adhesive Remnant Index and enamel fracture rate.

Results

The hydrophilic primer enhanced shear bond strength at first bonding (Assure™ PLUS 20.29 ± 4.95 MPa vs. Transbond XT™ 18.45 ± 2.57 MPa; BrackFix® 17 ± 5.2 MPa; Grengloo™ 19.08 ± 3.19 MPa; Meron 8.7 ± 3.9 MPa) and second bonding (Assure™ PLUS 16.76 ± 3.71 MPa vs. Transbond XT™ 13.06 ± 3.19 MPa). Using Plastic Conditioner did not seem to improve shear bond strength at rebonding (13.57 ± 2.94). When enamel etching was left out, required shear bond strength could not be achieved (Plastic Conditioner + Assure™ PLUS 8.12 ± 3.34 MPa; Plastic Conditioner: 3.7 ± 1.95 MPa). Hydrophilic priming systems showed decreased ARI-scores (second bonding: 2.63) and increased enamel fracture rates (first bonding: 55%; second bonding 21,05%).

Conclusions

Based on the present study we found that rebonding strength could be compensated by the use of hydrophilic priming systems. The additional use of a methyl methacrylate-consisting primer does not seem to enhance shear bond strength. No etching approaches resulted in non-sufficient bond strength.

Comparison of anchorage loss between conventional and self-ligating brackets during canine retraction - A systematic review and meta-analysis

INTRODUCTION

Anchorage is defined as the resistance to unwanted tooth movement. In orthodontics, loss of anchorage can be detrimental to treatment. The proponents of orthodontic self-ligating brackets (SLB) advocate the use of extremely light forces thereby reducing anchorage burden. Therefore, the aim of this study was to compare anchorage loss during canine retraction between conventional brackets (CB) and self-ligating brackets.

METHODS

An electronic search was conducted on the Cochrane database, Scopus, Web of Science, PubMed, Dental & Oral Science and CINAHL, along with handsearching Google Scholar and clinicaltrials.gov. Randomized or non-randomized clinical trials published in the English language on human subjects were included. Orthodontic patients undergoing canine retraction after premolar extraction bonded with self-ligating brackets as the intervention and conventional brackets as the control group in a split mouth design were included. Primary outcome studied was anchorage loss; secondary outcomes were retraction velocity and total amount of canine retraction. Two researchers carried out data extraction and study selection independently. The risk of bias was calculated using the Cochrane's Risk of Bias Assessment tool. The RevMan software was used for quantitative synthesis of data. Effect estimate of the primary and secondary outcomes was expressed using weighted mean difference and 95% confidence intervals (CIs). Heterogeneity of the studies was evaluated using the Cochrane's test for heterogeneity (I² Test); subgroup and sensitivity analyses were performed to investigate sources of heterogeneity among the studies.

RESULTS

Results of the literature search across all databases yielded 10,439 hits, out of which five studies were included in the qualitative synthesis that met the inclusion criteria. Four studies were randomized control trials (RCTs) where as one was a non-randomized control trial, with 100 subjects included in this systematic review. All studies used a split mouth design. Of the five studies included, only one reported significant differences between CB and SLB for anchorage loss, retraction velocity and total amount of canine retraction (P-value≤0.001). Four studies were included in the meta-analysis, which showed no difference in the amount of anchorage between self-ligating and conventional brackets (weighted mean difference - 0.22; 95% CI [-0.82, 0.38]; P=0.48). Multiple subgroup analyses further revealed there were no significant differences between the intervention and control groups for all outcomes studied.

CONCLUSION

This systematic review and meta-analysis found insufficient evidence to suggest a significant difference in anchorage loss between the CB and SLB groups. The scarcity of current evidence dictates that further studies are needed to canonically establish the clinical superiority of one over the other.

REVIEW REGISTRATION

PROSPERO 2019 CRD42019133217.

Dentoalveolar changes in adults promoted by the use of auxiliary expansion arch: A cbct study

Background

The objective of this study was to evaluate the dentoalveolar effects and the changes of buccal cortical bone in the posterior area after expansion obtained with TMA auxiliary expansion arch in adult patients.

Material and Methods

A retrospective analysis of CT scans of 13 patients (6 male, 7 female) treated at a private clinic, taken immediately before and after the use of an auxiliary expansion archwire, was performed. Mean age at installation of TMA auxiliary expansion arch was 29.23 years (s.d.=9.13) and the mean age when the auxiliary arch was removed was 29.52 years (s.d.=9.16). Mean time of the use of the TMA auxiliary expansion arch was 0.29 years (s.d.=0.09). The patients used fixed appliances and after leveling and alignment, a TMA auxiliary expansion arch was installed, combined with the primary 0.017x0.025-inch thermoactivated Ni-Ti archwire. CBCT scans were taken at T1 and T2. Linear and angular measurements regarding the positioning of maxillary molar, premolars and canines were performed. Intragroup comparison of the variables at T1 and T2 was performed with dependent t tests.

Results

There was statistically significant transverse increase and buccal inclination of all teeth. The cortical bone showed adaptability and displacement in the same direction of tooth movement, but in smaller amounts.

Conclusions

The auxiliary expansion arch proved to be effective to correct dentoalveolar constriction in adult patients, by increasing the buccal dental inclination with larger displacements than the bone crest adaptation and with significant transverse gains.

Key words:Cone-Beam Computed Tomography, Maxillary Expansion, Adult treatment.

Failure patterns of different bracket systems and their influence on treatment duration: A retrospective cohort study

OBJECTIVES

To compare the failure pattern of four different bracket types and to assess its effect on treatment duration.

MATERIALS AND METHODS

A total of 78 white patients (28 male, 50 female) with a mean age of 12.6 years were included in this retrospective cohort study and treated for a mean period of 30.6 months. The patients were treated in a private practice with stainless steel conventionally ligated brackets, ceramic conventionally ligated brackets, stainless steel self-ligating brackets, or nickel-free self-ligating brackets. The loss of at least one bracket during the course of treatment was analyzed with Cox proportional hazards survival analyses and generalized linear regression.

RESULTS

The overall bracket failure rate at the tooth level was 14.1% (217 brackets), with significant differences according to tooth type (between 8.0%-23.4%) and bracket type (between 11.2%-20.0%). After taking confounders into account, patients treated with ceramic brackets lost more brackets (hazard ratio = 1.62; 95% confidence interval = 1.14-2.29; P = .007) than patients with stainless steel brackets. On average, treatment time increased by 0.6 months (95% confidence interval = 0.21-1.05; P = .004) for each additional failed bracket.

CONCLUSIONS

Bracket failure was more often observed with ceramic brackets and was associated with increased treatment duration.

The effect of conventional versus figure-of-eight module ligation on mandibular incisor alignment: a randomised controlled trial

OBJECTIVE

To determine whether using figure-of-eight modules affects the rate of lower incisor alignment compared with conventionally tied modules.

DESIGN

Prospective randomised controlled trial.

SETTING

Orthodontic department at Queen's Hospital, Burton upon Trent, UK.

METHODS

One hundred and twenty participants were randomly allocated to conventional module or figure-of-eight module groups, stratified for extraction or non-extraction lower arch treatment. Eligibility criteria included patients who were 12-15 years of age at the start of treatment, in the permanent dentition, and had mandibular incisor irregularity of 5-10 mm (clinical observation). The primary outcome was the rate of lower incisor alignment during the first 12 weeks of orthodontic treatment. The secondary outcome was bracket failure rate. Lower labial segment alignment was measured on study models using the Little's Irregularity Index at the start (T0) of treatment, at 6 weeks (T1) and 12 weeks (T2). Case records were analysed to assess the number of bracket failures.

RESULTS

The four groups were well matched at baseline with respect to gender, age and irregularity. All patients completed the trial and data were analysed on an intention to treat basis. In both ligation groups, the lower teeth aligned significantly faster when the treatment involved extractions, for the time periods T0-T1 and T0-T2 (p < 0.05). There were no statistically significant differences between conventional module and figure-of-eight module ligation on the rate of alignment (per month) for all three-time periods. The bracket failure rate was also similar in both test groups; 4.08% for conventional and 3.21% for figure-of-eight ligation.

CONCLUSIONS

Ligation with figure-of-eight modules has no clinically significant effect on the rate of lower incisor alignment; it does not seem to hinder or quicken the alignment of teeth. There were no differences in the mean number of bracket failures per person.

Therapeutic efficacy of self-ligating brackets: A systematic review

INTRODUCTION

Over the last few years, the use of self-ligating brackets in orthodontics has progressed considerably. These systems have been the subject of numerous studies with good levels of evidence making it possible to evaluate their efficacy and efficiency compared to conventional brackets. The aim of this study was to evaluate the therapeutic efficacy of self-ligating brackets by means of a systematic review of the scientific literature.

MATERIALS AND METHODS

A systematic study was undertaken in the form of a recent search of the electronic Pubmed database, oriented by the use of several keywords combined by Boolean operators relating to the therapeutic efficacy of self-ligating brackets through the study of tooth alignment, space closure, expansion, treatment duration and degree of discomfort. The search was limited to randomized controlled studies, and two independent readers identified studies corresponding to the selection criteria.

RESULTS AND DISCUSSION

The chosen articles comprised 20 randomized controlled trials. The studies analyzed revealed the absence of significant differences between the two types of system on the basis of the clinical criteria adopted, thereby refuting the hypothesis of the superiority of self-ligating brackets over conventional systems.