Effects of fixed functional appliances with temporary anchorage devices on Class II malocclusion: A systematic review and meta‑analysis

Is significant mandibular advancement possible after the peak of puberty? Dento-osseous palatal expansion and the STM4 technique (Skeletal Therapy Manni Telescopic Herbst 4 miniscrews): A case report

INTRODUCTION

Treatment of skeletal class II growing patients often requires the use of functional appliances, aimed at promoting mandibular advancement. Among these, Herbst appliance is recommended for its effectiveness, efficiency, and reduced need for compliance. Despite its skeletal favourable effects, well-known dental compensations can occur, especially when the appliance is not used close to the pubertal peak: upper incisors retroclination, lower incisors proclination, upper molars distalization and lower molars mesialization could reduce the overjet needed for a proper mandibular advancement. To counteract these unfavourable effects skeletal anchorage could be crucial.

AIM

The aim of this case report is to describe and evaluate the effects of using a skeletally anchored Herbst appliance in an 18-year-old (CVM5) male patient with skeletal Class II malocclusion and a convex profile.

TREATMENT PROTOCOL

The treatment started with a tooth-bone-borne palatal expansion, then the upper arch was bonded with pre-adjusted ceramic brackets. After 2months, a Manni Telescopic Herbst (MTH) supported by 4 miniscrews (two in the maxilla and two in the mandible) was applied. To avoid anchorage loss, TADs were connected with elastic chains to the arches. Nine months later, the Herbst was removed, the lower teeth were bonded and the patient wore class 2 elastics to stabilise the occlusion.

RESULTS AND CONCLUSIONS

After 24months the treatment goal was achieved with a considerable improvement of the profile and a clinically significant mandibular advancement (Pogonion moved forward 7mm). A one-year follow-up lateral X-rays showed a good stability of the result.

Evaluation of the Co-Go-Me angle as a predictor in Class II patients treated with Herbst appliance and skeletal anchorage: a retrospective cohort study

Introduction

A condylion-gonion-menton (Co-Go-Me) angle threshold of 125.5° has been introduced as a predictive parameter of cephalometric mandibular response in the orthopedic treatment of growing Class II patients with functional appliances, despite some contradictions in the literature. Considering the lack of studies evaluating the role of skeletal anchorage, this study aims to reassess the threshold of 125.5° in the Co-Go-Me angle as a useful predictor in growing skeletal Class II patients treated with acrylic splint Herbst appliance and two mini-screws in the lower arch (STM2).

Methods

Thirty-five consecutively treated patients (20 males, 15 females; mean age, 11.37 years) with mandibular retrusion were classified into two groups according to their Co-Go-Me baseline values (Group 1, <125.5°; Group 2, >125.5°). The STM2 protocol involved the use of the MTH Herbst appliance with an acrylic splint in the lower arch and two interradicular mini-screws as anchorage reinforcement. Cephalometric analysis was performed by the same operator for each patient at baseline (T0) and at the end of the Herbst phase (T1). The effects of time and group on the variables were assessed by a repeated-measures analysis of variance. The primary research outcome was the difference between the groups in terms of mandibular responsiveness to treatment referred to as the relative difference (T1-T0) in Co_Gn.

Results

The mean duration of the treatment was 9.5 months. No statistically significant differences between groups were detected at baseline, except from the expected SN/GoMe° (p < 0.001) and Co-Go mm (p = 0.028). No statistically significant changes between groups, which were caused by the treatment, were found considering the mandibular sagittal and vertical skeletal parameters. Similarly, no statistically significant differences were found in the dental changes between the high-angle and low-angle patients, apart from the upper molar sagittal position (p = 0.013).

Discussion and conclusions

The 125.5° threshold in the Co-Go-Me value was not a reliable predictive parameter for the mandibular response in growing patients treated with the MTH Herbst appliance and lower skeletal anchorage. Due to its effective control in the sagittal and vertical planes, the STM2 technique might be an appropriate protocol to use in treating skeletal Class II patients, regardless of the growth pattern.

Effects of skeletal anchorage on mandibular rotation with fixed functional appliance therapy in class II malocclusion patients – A systematic review and meta-analysis

Objectives:

The study aimed to systematically investigate the effect of skeletal anchorage on mandibular rotation during FFA therapy during Class II correction in adolescents.

Material and Methods:

The review protocol was registered under the PROSPERO database (CRD42021256690). Electronic searches of databases and screening were performed up to May 2022. Only randomized clinical trials (RCT) and non-randomized controlled trials (non-RCT) were included in the study. Revised Cochrane risk-of-bias tool for RCTs (RoB 2) and risk of bias in non-randomized studies-of interventions tool for non-RCT were used for studies. Meta-analysis was performed and a forest plot was obtained. The primary outcome was mandibular rotation. Other outcomes assessed were angles SNA, SNB, ANB, mandibular incisor proclination, and failure rates of mini-screws and mini plates.

Results:

Twelve studies (eight RCTs and four non-RCTs) were included fulfilling inclusion criteria. Evidence showed a low-to-moderate risk of bias for different domains. Meta-analysis for mandibular rotation revealed a greater increase in mandibular plane angle in patients who received FFA with skeletal anchorage as compared to patients who did not receive skeletal anchorage.

Conclusion:

With or without skeletal anchorage, mandibular rotational changes during FFA therapy are similar. FFA when combined with skeletal anchorage causes more skeletal changes in sagittal parameters than conventional FFA used alone. FFA with skeletal anchorage reduces lower incisor proclination.