Effectiveness of incremental vs maximum bite advancement during Herbst appliance therapy in late adolescent and young adult patients

Class II subdivision treatment and stability with asymmetric Herbst appliance: A case report

Non-surgical treatment of Class II subdivision may involve complex mechanics or asymmetric tooth extraction in its resolution. This report demonstrates the result and the short-term stability of Class II subdivision treated with asymmetrically installed Herbst appliance followed by conventional fixed orthodontic appliance. The approach allowed the correction of the unilateral Class II molar relationship and increased overjet, as well as the deviation of dental midlines, with improvement in lip posture and facial profile. The results remained stable two years after treatment, confirming the treatment success.

Comparisons of soft tissue changes after Herbst appliance treatment in three different growth phases

BACKGROUND

This study aimed to compare the soft tissue effects of Herbst appliance in Class II malocclusion patients treated in three different craniofacial growth phases: prepubertal (PRE), circumpubertal (CIR), and postpubertal (POS).

METHODS

In total, 95 patients with Class II Division 1 malocclusion previously treated with a Herbst appliance were analyzed. Through the cervical vertebral maturation stages method, patients were allocated into three groups depending on the growth craniofacial phase at the beginning of treatment: PRE, CIR, and POS. Seventeen cephalometric measures were evaluated from each lateral radiograph before and after Herbst therapy using the Radiocef 2 software (Radio Memory, Belo Horizonte). Intragroup and intergroup treatment changes were compared statistically using a paired t test and MANOVA test, respectively.

RESULTS

Soft tissue thickness changes were related only to mandible; all three mandibular measurements (L1_LL, B_B', and Pog_Pog') showed thickening for the PRE group ranging from 0.92 mm (Pog_Pog') to 2.02 mm (B_B'), and only lower lip thickened overtime for the POS group (L1_LL = 0.99 mm). Soft and hard tissue pogonion displaced anteriorly, but only the soft tissue showed differences among groups; PRE group presented more anterior displacement than POS group (3.61 mm and 1.39 mm, respectively). Hard and soft tissue facial convexity decreased more in the PRE and CIR groups than in the POS group. Mentolabial sulcus depth reduced more in the PRE (1.07 mm) and CIR (1.29 mm) groups than in the POS (0.55 mm) group. Horizontal movement of the skeletal and soft pogonion presented a moderate-high positive correlation (r = 0.783), and hard and soft facial convexity showed a moderate-low positive correlation (r = 0.403).

CONCLUSIONS

Herbst appliance therapy produces soft tissue improvements in the three phases of craniofacial growth, being greater in patients in the PRE and CIR phases.

Three-dimensional skeletal and dentoalveolar sagittal and vertical changes associated with cantilever Herbst appliance in prepubertal patients with Class II malocclusion

INTRODUCTION

This study aimed to assess sagittal and vertical skeletal and dentoalveolar changes through the use of 3-dimensional imaging in prepubertal Class II malocclusion patients treated with a cantilever Herbst appliance (HA). Condyle-glenoid fossa positional changes were also quantified.

METHODS

This retrospective cohort study assessed 22 children (11.2 years ± 1.2) consecutively treated with a cantilever HA for 12 months and 11 untreated children (aged 9.3 ± 0.30 years) that served as controls. Cone-beam computed tomography was performed at baseline (T1) and at the end of the observation period (T2). Movements in the regions of interest were measured as linear displacements from cone-beam computed tomography images through algebraic calculations. A Student t test for independent samples was used for group equivalence testing at T1, and the treatment differences between T2 and T1 were evaluated by 2 analyses of covariance, one considering the expected growth unit as a covariate and the other with an annualized factor.

RESULTS

The largest dental movement was a mesial movement of mandibular molars (3.70 mm), whereas the largest skeletal changes consisted of a larger relative length of the mandible (difference of 1.2 mm) in the HA group than in the control group.

CONCLUSIONS

Within the study limitations (retrospective cohort, historical control group, and sample size), 3-dimensional imaging suggests that HA corrected Class II malocclusion in a predominantly prepubertal sample through more dental than skeletal changes. The changes were more significant in the sagittal than in the vertical direction. In addition, relative stability in the condyle-fossa relationship was noted.

Treatment and posttreatment effects of Herbst appliance therapy on trabecular structure of the mandible using fractal dimension analysis

OBJECTIVES

This controlled study aimed to evaluate the effects of Herbst therapy on the trabecular structure of the condyle and angulus mandible using fractal dimension analysis (FD-A) accompanied by skeletal cephalometric changes.

MATERIAL AND METHOD

The panoramic and cephalometric radiographs of 30 patients with skeletal Class II malocclusion treated with the Herbst appliance (C II-H group, mean age: 15.23 ± 1.08), 30 patients with skeletal Class II malocclusion that received fixed orthodontic treatment (C II-C group, mean age: 15.73 ± 1.38), and 30 patients with skeletal Class I malocclusion (C I-C group, mean age: 15.90 ± 1.30) were selected. FD-A was performed on the superoposterior region (C-SP) and centre of the condyles (C-C) and the mandibular angulus (Ang) on the panoramic radiographs taken at the pretreatment (T0), intermediate stage of treatment (T1), and posttreatment (T2) timepoints just like cephalometric analysis.

RESULTS

Herbst therapy provided a statistically significant increase in SNB, ANS-Me, Na-Me, S-Go, Co-Gn and a decrease in ANB and overjet (P < 0.05). All skeletal changes remained stable during the fixed appliance treatment after Herbst. The FD values in C-C increased (P < 0.05), and C-SP values decreased (P < 0.05) during Herbst therapy, while after removal of the Herbst appliance, no significant change was observed despite an increase in C-SP. The Ang value did not change during Herbst treatment, but then increased significantly (P < 0.05). There was no significant change in the FD values of the C I-C and C II-C groups at any stage of treatment. The C-C and C-SP changes at T1-T0 period, C-SP and Ang changes at T2-T1 period, and C-C, C-SP, and Ang values at T2-T0 period were found higher in C II-H group compared with the C II-C group significantly (P < 0.05).

CONCLUSION

Herbst therapy changed the trabecular structure of the condyles in different directions at the superoposterior and central regions of the condyles, while the structural complexity of the angulus mandible, which did not change during the Herbst treatment, increased during the fixed orthodontic treatment after Herbst.

Changes in the craniofacial structures and esthetic perceptions of soft-tissue profile alterations after distalization and Herbst appliance treatment

INTRODUCTION

The purpose of this prospective clinical trial is to evaluate the changes of soft tissues and designate the esthetic perceptions of children with Class II malocclusion after Herbst appliance therapy and maxillary molar distalization using stereophotogrammetry.

METHODS

Thirty patients were allocated either to Herbst (6 boys and 9 girls; mean age = 11.60 ± 0.82 years) or distalization (4 boys and 11 girls; mean age = 11.46 ± 1.30 years) groups. Dentoskeletal and soft-tissue treatment changes were examined objectively by cephalometric analysis and stereophotogrammetry, respectively. Pre- and posttreatment profile views were evaluated subjectively by orthodontists and laypeople using the 7-point Likert scale. Intra- and intergroup comparisons for the repeated measurements were performed with 2-way variance analysis. Bonferroni test was used for multiple comparisons (P ≤0.05).

RESULTS

Greater skeletal changes were observed in the Herbst group than in the distalization group. Maxillary incisor retrusion and mandibular incisor protrusion were observed in the distalization and Herbst groups, respectively. Stereophotogrammetric measurements showed that mandibular body length and lower and anterior facial height increased in both treatment groups. Convexity angle (P = 0.020) and labiomental angle (P = 0.033) were greater in the Herbst group than the distalization group.

CONCLUSIONS

The skeletal contribution to correction of maxillomandibular discrepancy was greater in the Herbst group than the distalization group. Significant profile improvements were recorded for both groups with treatment. After both treatments, orthodontists were found to have higher rates of detection in the profiles than laypeople. The esthetic contribution of treatments to the facial profile was found similar in both groups.

Angle class II correction: stepwise mandibular advancement or bite jumping? : A systematic review and meta-analysis of skeletal, dental and condylar effects

INTRODUCTION

There is no consensus regarding which mode of activation or mandibular advancement (stepwise [SW] or maximum bite-jumping [BJ]) of fixed or removable functional appliances (FFA; RFA) for correction of Angle class II malocclusion is advantageous to produce dental, skeletal or condylar effects and has the lowest rate of undesired dental or technical side-effects.

METHODS

A systematic search was conducted up to Oct. 20, 2019 in the MEDLINE, EMBASE, Scopus, Central Cochrane Library, and BBO databases. Included were preadolescent, adolescent, and adult humans with initial (pretreatment) Angle class II malocclusion, without further restriction. The intervention group was composed of subjects treated with FFA or RFA in SW mandibular advancement; the control group received BJ advancement. Search terms included prospective randomized and nonrandomized trials in English, German, Spanish, and Portuguese with the primary outcomes of skeletal and dental class II correction, effects on condylar growth, lower incisor proclination, overjet and overbite reduction. The risk of bias (ROB) was assessed using the Cochrane Collaboration's ROB2 tool. Mean differences were calculated and pooled by a meta-analysis using a random effects model.

RESULTS

Data from five randomized controlled trials (RCT) with 401 participants (mean age 13.84 years; SD 1.53) were included; 331 derived from four studies were included in the meta-analysis. The ROB in the selected articles was high. We detected a slightly increased reduction of the ANB (mean difference [MD] -0.95°, 95% confidence interval [CI] -1.80 to -0.10°; I² = 72%) that may be attributed to a slightly more pronounced increase of the SNB angle in SW-advanced mandibles (MD 0.27°; 95% CI -0.47 to 1.00°; I² = 38%). SW advancement tended to reduce the undesired side effect of lower incisor proclination (MD = -1.59°; 95% CI -3.98 to 0.8°; I² = 0%), indicating more pronounced mandibular incisor changes with bite-jumping advancement.

CONCLUSION

There is weak evidence indicating a slightly increased reduction of the ANB and less lower incisor proclination with SW advancement compared to BJ, but the clinical relevance is debatable due to the small overall magnitude and small number of high-quality papers.

REGISTRATION

Prospero #CRD42017075469 (www.crd.york.ac.uk/prospero).

Stepwise versus single-step mandibular advancement with functional appliance in treating class II patients : A meta-analysis

BACKGROUND

Difference in the functional orthopedic effect between stepwise mandibular advancement (SWA) and single-step mandibular advancement (SSA) in Angle class II patients remains unclarified.

OBJECTIVE

To compare the treatment effects of SWA and SSA on skeletal and dentoalveolar changes in class II patients.

METHODS

Randomized controlled trials (RCTs) and nonrandomized studies that compared differences in skeletal and dentoalveolar effects on class II patients between SWA and SSA were identified in PubMed, Embase, CENTRAL, and Web of Science. The grey literature was also searched. The primary outcomes were the mandibular length, L1-MP, and (ANB). Secondary outcomes included Pog sagittal, SNB, overjet, and mandibular plane angle.

RESULTS

Seven studies, including three RCTs and four cohort studies, were retrieved. Meta-analyses revealed pooled mean differences (95% confidence interval) of 0.79 mm (0.45 to 1.12 mm) for Pog sagittal, 0.53° (0.19 to 0.87°) for SNB, -0.51° (-0.83 to -0.20°) for ANB, -0.17° (-0.72 to 0.39°) for the mandibular plane angle, -0.41 mm (-0.90 to 0.09 mm) for overjet, -1.87° (-3.23 to -0.52°) for L1-MP, and 1.03 mm (0.63 to 1.42 mm) for the mandibular length. Publication bias was not observed, except for Pog sagittal. The quality of evidence for each outcome was judged as low (mandibular length, SNB and overjet) and very low (Pog sagittal, ANB, L1-MP and mandibular plane angle).

CONCLUSIONS

Although the magnitude of differences in clinical practice was limited, SWA might be more appropriate because it produces a greater skeletal change and less dental compensation than SSA. As the level of current evidence is low, more high-quality RCTs are needed.

Incremental or maximal mandibular advancement in the treatment of class II malocclusion through functional appliances: A systematic review with meta-analysis

To systematically review the effects of functional appliances (FA) using incremental vs maximal mandibular advancement regarding cephalometric measurements in class II malocclusion individuals and to assess patient-centred-outcomes. Six electronic databases were searched without restrictions up to April 2020. We included randomized and non-randomized controlled trials using identical FA. Trials involving participants who used adjunct appliances, inter-maxillary elastics, who received surgical treatment or that recruited individuals with cleft lip/palate or craniofacial deformity/syndrome were excluded. Risks of bias assessments were performed using the Cochrane risk of bias tool-2 and ROBINS-I tools. Mean differences (MD) with their 95% confidence intervals were calculated from random-effects meta-analyses. The GRADE tool was used to assess the certainty of the evidence. Six studies were included. Low to very low certainty of evidence indicated that incremental mandibular advancement resulted in greater gains in mandibular length (MD = 0.89 [0.38, 1.34], P = .0005), anterior mandibular displacement (MD = 0.73 [0.40, 1.06], P < .0001) and SNB angle (MD = 0.44 [0.02, 0.85], P = .04). No significant differences were found for maxillary, dento-alveolar and upper airway outcomes between construction bite protocols (P > .05). Study design and appliance-related factors influenced the results of the subgroup analyses. Existing evidence is inadequate to assess patient-related response and long-term outcome could not be assessed. Currently, there are a heterogeneous number of studies with low quality and methodological issues can lead to biases that strongly limit an evidence-based conclusion. Weak evidence suggests gains in mandibular skeletal parameters in the short term using FA with incremental mandibular advancement. Randomized trials evaluating key topics such as patient-centred outcomes need to be conducted to guide clinical management. PROSPERO (CRD42019147436).

Mandibular propulsion appliance for adults with Class II malocclusion: a systematic review and meta-analysis

BACKGROUND

The effects of mandibular propulsion appliances in adults have some controversial results. While some authors claim that its use in non-growing patients could produce some dentoskeletal effects, other studies indicate that Class II correction occurs only through significant dental effects.

OBJECTIVE

To evaluate the effects in non-growing Class II patients with mandibular retrusion, promoted by the treatment with mandibular propulsion appliances and determine if they produce mandibular changes.

METHODS

The research was carried out in nine electronic databases and additional manual searches up to July 2019. Selection criteria were no restriction was placed on date and publication language. Randomized or non-randomized clinical trials with/without control were included. They must evaluated non-growing patients with Class II malocclusion, treated with mandibular propulsion appliances; outcomes were assessed before and after treatment.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent examiners in duplicate. The ROBINS-I tool was used to assess the methodological quality of the included studies.

RESULTS

Of the 2824 articles identified, 11 non-randomized clinical articles were selected for qualitative analysis and 8 for quantitative analysis. SNB (0.87°, CI 95% 0.08, 1.66), ANB (-0.82°, CI 95% -1.24 to 0.40) and Pg/OLp [2.3 to 1.2 mm (P < 0.001)] presented smallest but significant mandibular changes with some differences regarding the used appliance. The Herbst appliance showed the largest mandibular changes followed by the SUS appliance when evaluated through Ar-Pg. SNA showed non-significant changes. Overbite (-2.85. CI 95% -3.06, -2.64), Overjet (-5.00.CI 95% -5.45, -4.55) showed significant changes in all devices. Class II correction occurs through a significant labial movement of the mandibular incisors, some lingual inclination of the maxillary incisors and minor skeletal changes.

CONCLUSIONS

All mandibular propulsion appliances examined, showed efficiency in normalizing the Class II malocclusion in adult patients; however, changes were acquired mainly through dentoalveolar changes. Some minor mandibular forward changes was noted, mainly in patients treated with the Herbst appliance. Randomized clinical trials are needed to improve scientific evidence.

REGISTRATION

PROSPERO (code CRD42017067384).

Influence of Vertical Facial Growth Pattern on Herbst Appliance Effects in Prepubertal Patients: A Retrospective Controlled Study

Introduction

The Herbst device is widely used for correction of class II malocclusions; however, most of the researches carried out on the Herbst appliance in literature do not take into account patients with a different mandibular divergence. The aim of this study was to investigate the effects of Herbst on dental and skeletal structures and to evaluate possible influence of vertical facial growth patterns.

Methods

A retrospective study was conducted on lateral cephalograms of 75 growing patients (mean age: 9.9 ± 1.9 years) with class II malocclusion treated with Herbst. Subjects were divided into 3 groups using the mandibular divergence index (SN and GoMe angle). Cephalometric parameters were evaluated using the modified SO (sagittal occlusion) Pancherz's analysis. A statistical analysis was conducted to evaluate differences among groups using ANOVA.

Results

Our study showed differences in response to treatment depending on patient's facial vertical growth pattern. Cranial base angle and mandibular rotation were significantly different (p < 0.05) between hypodivergent patients and normodivergent patients and between hypodivergent and hyperdivergent subjects.

Conclusion

Hypodivergent patients increased their mandibular divergence during treatment to a greater extent than normodivergents; moreover, hyperdivergent patients exhibited a decreased mandibular divergence at the end of the treatment.