A comparison of skeletal and dental changes in patients with a Class II relationship treated with clear aligner mandibular advancement and Herbst appliance followed by comprehensive orthodontic treatment

Precision wings treating skeletal class II in growing patients: a systematic review and meta-analysis

BACKGROUND

Skeletal Class II malocclusion, often associated with mandibular deficiency, is commonly treated with functional appliances. Precision Wings are a functional appliance that provides an alternative approach by combining mandibular advancement with dental alignment.

OBJECTIVE

This systematic review aimed to evaluate the effectiveness of Precision Wings in treating skeletal Class II malocclusion in growing patients.

ELIGIBILITY CRITERIA

Studies assessing the correction of skeletal Class II malocclusion in growing patients treated with Precision Wings were selected according to the PICOS strategy. The PRISMA guidelines were followed.

INFORMATION SOURCES

Unrestricted electronic searches were conducted across seven databases up to February 2025.

RISK OF BIAS AND SYNTHESIS OF RESULTS

The ROBINS-I tool was used to assess the risk of bias (RoB) in non-randomized studies. A random-effects meta-analysis was performed, and the certainty of the evidence was evaluated using the GRADE approach.

RESULTS

Seven studies were included, and data were extracted. Mean differences (MDs) with 95% confidence intervals (CIs) were calculated using random-effects meta-analysis. The findings suggest that Precision Wings may be effective in treating skeletal Class II malocclusion in growing patients through both dental and skeletal changes. Regarding skeletal effects, sagittal changes were limited to the mandible and were of small magnitude, with a reduction in ANB° (MD = -0.81; 95% CI: -1.04 to -0.58; p < 0.001) occurring exclusively due to an increase in SNB° (MD = 0.55; 95% CI: 0.11 to 0.98; p = 0.01), while no significant changes were observed in SNA° (MD = -0.02; 95% CI: -0.42 to 0.38; p = 0.91). The included studies did not report significant vertical effects. Meta-analyses comparing Precision Wings with other functional appliances were not feasible due to the small number of studies evaluating each comparison and the substantial clinical and methodological heterogeneity across the included studies.

CONCLUSION

Although the available scientific evidence on this topic is limited, treatment with Precision Wings appears to offer minimal clinical improvement in mandibular growth for the correction of skeletal Class II malocclusion. To obtain more conclusive findings, future research should prioritize well-structured randomized clinical trials with standardized treatment protocols, extended follow-ups, and consistent cephalometric assessment methods.

Temporomandibular joint condylar/fossa positional changes after Herbst and Xbow treatments in adolescents assessed through cone-beam computed tomography imaging: A randomized controlled trial

INTRODUCTION

This 3-arm parallel randomized clinical trial evaluated the 3-dimensional positional changes (anteroposterior, vertical, and mediolateral) in the condyle and glenoid fossa using different Class II fixed mandibular positioners/appliances (Herbst and Xbow) compared to a control group.

METHODS

A total of 54 patients were included and randomly assigned to 1 of 3 groups (Herbst, Xbow, and control) and followed up for an average of 12.4 months. Two cone-beam computed tomography images corresponding to pretreatment and posttreatment were taken for each patient. The mandibular condyle and glenoid fossa position relative to the reference planes were assessed using Avizo software (Thermo Fisher Science, Berlin, Germany) and landmark-to-plane distance calculation. Reliability was assessed using the intraclass correlation coefficient (ICC). Multivariate analysis of variance was conducted to determine the differences among the groups.

RESULTS

Intrarater reliability displayed high reliability with an ICCx (ICC for x-axis measurements) of 0.99 (95% confidence interval, 0.98-1.00) and ICCy (ICC for y-axis measurements) and ICCZ (ICC for z-axis measurements) of 1.00 (95% confidence interval, 1.00-1.00) with P <0.0026. Regarding all dimensional positional changes (anteroposterior, mediolateral, and vertical), there was no significant difference in means of variations in the orthogonal distance of the condyle and glenoid fossa landmarks based on groups (P >0.05).

CONCLUSIONS

Fixed Class II orthodontic appliances (Herbst and Xbow) did not show condyle or glenoid fossa position changes relative to the reference planes formed by the cranial base and facial landmarks or change in position of the condyle relative to the glenoid fossa compared to the control group.

TRIAL REGISTRATION

The study was registered with the International Standard Randomised Controlled Trial Number registry with registration No. ISRCTN57079737, retrospectively registered on October 21, 2022 (https://www.isrctn.com/ISRCTN57079737?q=ISRCTN57079737&filters=&sort=&offset=1&totalResults=1&page=1&pageSize=10).

PROTOCOL

International Standard Randomised Controlled Trial No. ISRCTN57079737.

FUNDING

This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

Oral Implications of Herbst Device Modification: A Case Report

BACKGROUND

Many studies analyse the effectiveness of the Herbst device in the treatment of dentoskeletal Class II malocclusion due to mandibular retrusion. This fixed device was devised by Emil Herbst for Class II treatment using a bite jumping, i.e., a device that holds the jaw in a forced anterior position. Comparison of the results obtained in numerous studies is difficult because they are often not comparable and not congruent due to a number of variables that prevent standardization.

METHODS

The purpose of the present study is to report some clinical-level considerations that may be important in order to obtain more predictable therapeutic outcomes. The simplified design of the Herbst device offers better patient comfort and easier cleanability but may show some disadvantages, such as less anchorage.

RESULTS

The device was evaluated in conjunction with the multi-bracket phase that preceded Herbst therapy and concluded after the device was removed. The therapy was performed in the absence of skeletal anchorage.

CONCLUSIONS

In our opinion, standardization of therapy according to precise protocols may positively affect the therapeutic outcomes by achieving faster occlusal stabilization, more proper neuro-muscular balance, less stress on anchor units, and shorter treatment time.

Coefficient of efficiency and effectiveness of functional appliances in class II malocclusion treatment : A systematic review

OBJECTIVE

To evaluate the coefficient of efficiency and effectiveness of removable and fixed functional appliances in class II malocclusion treatment.

DATA SOURCES

Search of studies in five databases (Medline via PubMed, Cochrane library, LILACS, SCOPUS, and SciELO) that measured mandibular skeletal changes following functional therapy was conducted until 15 April 2024.

STUDY SELECTION

All study designs including randomized and controlled clinical trials (RCT), prospective and retrospective studies were included. Data were extracted independently by two authors from studies that fulfilled the inclusion criteria. Mandibular length changes of class II patients treated with functional appliances were collated for each retrieved study.

RESULTS

From 6796 potentially eligible studies, 90 were considered for this systematic review. Four were RCTs which were graded with the Cochrane risk of bias tool. Three were assessed as having low and one as having moderate risk of bias. The other 86 studies were graded with the modified Downs and Black tool which revealed that 47 showed low, 38 low/moderate, and 1 a moderate risk of bias. The most commonly assessed appliances were the Twin Block which was used on 783 patients, the Frankel appliance on 573, the Herbst appliance on 530, the Activator on 449, the Forsus appliance on 394, the MARA appliance on 202, and the Bionator on 133, for a total of 3064 treated patients.

CONCLUSION

This systematic review provides conclusive evidence that the Twin Block appliance demonstrated the highest coefficient of efficiency among all the evaluated appliances (0.46 mm/month), while the Forsus fatigue resistant device (FFRD) had the highest coefficient of efficiency among the fixed functional appliances (0.41 mm/month).

Interceptive Treatment of Class II Malocclusion in Pediatric Patients Using Clear Aligner Mandibular Advancement: A Systematic Review Following PRISMA Guidelines

While conventional functional appliances have been widely used to manage Class II malocclusion in growing pediatric patients, advancements in interceptive treatments have introduced aligner mandibular advancement as a modern and aesthetic alternative. Despite its increasing popularity, the effectiveness of aligner mandibular advancement has not been systematically evaluated. This systematic review aimed to evaluate the effectiveness of interceptive aligner mandibular advancement in the treatment of Class II malocclusion in pediatric patients, focusing on skeletal, dental, and soft tissue outcomes. This review adhered to the Preferred Reporting Items for Systematic reviews and Meta-Analyses or PRISMA guidelines. Studies evaluating pediatric patients with Class II malocclusion treated with aligner mandibular advancement were included. The databases searched included PubMed, Cochrane Library, Web of Science, Embase, and Scopus, with searches conducted up to November 30, 2024, to identify relevant articles addressing the PICOS framework (Population, Intervention, Comparison, Outcome, and Study design). The focus questions were: How effective is clear aligner mandibular advancement in the treatment of pediatric patients with Class II malocclusion? What are its associated treatment outcomes? The ROBINS-I tool was used to assess the risk of bias. Data were synthesized narratively due to heterogeneity in study designs and outcomes. Nine studies with 426 participants were included, conducted between 2021 and 2024. Seven studies adopted retrospective designs, one study used a prospective design, and one relied on a survey-based design. Aligner mandibular advancement demonstrated effectiveness in reducing overjet and ANB while maintaining lower incisor inclination compared to conventional functional appliances. Soft tissue improvements were also reported. Patients favored aligner mandibular advancement over conventional functional appliances for its superior comfort, better aesthetics, and less breakage. However, most studies were retrospective, and the lack of randomized controlled trials limited the strength of the evidence. Clear aligner mandibular advancement appears to be an effective approach for managing Class II malocclusions in growing pediatric patients, offering the distinct advantage of maintaining lower incisor inclination compared to other conventional functional appliances. However, the evidence remains limited due to methodological constraints, including the lack of randomized controlled trials, small sample sizes, and inconsistencies in study designs.

Characteristics of skeletal Class II adolescents with favorable facial attractiveness outcomes based on 3D photos after Twin-block treatment

INTRODUCTION

This study aimed to investigate the hard tissue and soft tissue characteristics related to favorable facial attractiveness outcomes of Class II Twin-block treatment to select suitable patients for this therapy.

MATERIAL AND METHODS

A total of 86 skeletal Class II patients who had undergone Twin-block treatment were included in this study. Post-treatment facial attractiveness was assessed by seven orthodontists using visual analog scale (VAS) scores based on 3D photographs. Patients were ranked according to their VAS scores, with the top 26 individuals classified as the favorable group and the bottom 26 as the unfavorable group. Soft tissue and hard tissue measurements were obtained from their 3D photos and lateral cephalograms, and intergroup comparisons were conducted using the independent t-test and Mann-Whitney test.

RESULTS

The favorable group exhibited significantly lower values for Co-pog, FH-MP, L1-APog, Li-H Line, and Total Convexity Angle before treatment, according to independent t-tests and Mann-Whitney tests. Conversely, the favorable group demonstrated significantly higher values for the Wits appraisal, Pog-NB, S-Go/N-Me, Si-H and Ch_R-Li-Ch_L were larger(P < 0.05).

CONCLUSIONS

Patients with low divergent skeletal patterns, a well-developed chin, upright lower incisors, a flat lower lip, and a large amount of skeletal discrepancy between the maxillary and the mandibular are likelier to achieve favorable facial attractiveness outcomes following Twin-block treatment.

Planned and achieved overjet and overbite changes following an initial series of Invisalign® aligners: A retrospective study of adolescent patients

OBJECTIVE

The aim of the present study was to compare the changes in overjet and overbite measurements achieved in adolescent patients following an initial series of Invisalign® aligners (Align Technology, San Jose, California) with those planned by orthodontists via its ClinCheck® digital treatment planning facility.

METHODS

Data provided by Align regarding patients who had completed an initial series of Invisalign® aligner treatment and were less than 18-years old were assessed in relation to pre-treatment, planned and achieved overjet and overbite measurements. Descriptive statistics, Wilcoxon rank-sum, Mann Whitney calculations were computed.

RESULTS

A total of 290 patients satisfied inclusion criteria. The median (interquartile range (IQR)) age was 14.17 (13,15.42) years. The median achieved overjet and overbite changes were less than those planned (p<0.01) with 53.33% of the planned median overjet increase achieved and 52.94% of planned median overjet reduction achieved. Additionally, 58.33% of the planned median overbite increase was achieved and 55.55% of the planned median overbite reduction was achieved. A total of 21.52% patients recorded no change or an increase from pre-treatment to the achieved overjet where reduction was planned, whereas 41.67% recorded no change or a reduction in overjet where increase was planned. A total of 18.72% recorded no change or an increase in overbite where reduction was planned, whereas 20.75% recorded no change or a reduction in overbite where increase was planned.

CONCLUSIONS

Less than 60% of the planned overjet and overbite changes per patient were achieved. Between 18.72 and 41.67% of patients experienced no change or changes in overjet and overbite in the opposite direction to that planned. This is likely to be clinically significant.

Evaluation of modified clear Twin Block aligner in treating adolescents with skeletal class II malocclusion: A two-centre cephalometric study

INTRODUCTION

The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion.

METHODS

A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre-treatment (T1) and post-treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent-sample t-test, paired-sample t-test, ANOVA test and Scheffe's Post Hoc test.

RESULTS

Seventy-five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms-S Vert/Mi in the CTB group (P < .01) and the TB group (P < .001), as well as deep overjet through significant different in S Vert/Is-S Vert/Ii in the CTB group (P < .001) and the TB group (P < .001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities.

CONCLUSIONS

For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance.