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.

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.

Six years long term evaluation of a class II division 1 patient treated with Herbst appliance and 2 miniscrews in the lower arch as anchorage reinforcement: A case report.

BACKGROUND: Efficacy of orthopaedic treatment of class II growing patients have been reported to be partially effective, depending on appliance efficacy, patient compliance, growth spurt and other variables. Different approaches have been proposed both removable and fix, with different results, and a dento-alveolar compensation was always reported. In order to limit or avoid such dental compensation skeletal anchorage reinforcement of functional appliances have been proposed, with promising results. OBJECTIVE: The aim of the present report is to evaluate the dento-skeletal effects after 6 years of growing class II patient treated with Herbst and two miniscrews in the lower arch as anchorage reinforcement.

Success rate of surface-treated and non-treated orthodontic miniscrews as anchorage reinforcement in the lower arch for the Herbst appliance: A single-centre, randomised split-mouth clinical trial.

BACKGROUND: Surface treatment of miniscrews was implemented to determine whether its application increased bone-to-surface contact and enhanced the interlock between the device and the surrounding bone. OBJECTIVES: To compare the success rate of surface-treated and non-treated orthodontic miniscrews used as reinforcement of anchorage during treatment with the Herbst appliance. TRIAL DESIGN: Split-mouth design with an allocation ratio of 1:1. METHODS: Eligibility criteria to enrol patients were skeletal and dental class II patients with a retrusive chin, use of the Herbst appliance to correct malocclusion, need for skeletal anchorage using a miniscrew both in the left and right side of the mouth, absence of systemic diseases, absence of using drugs that alter bone metabolism, and good oral hygiene. Patients received self-drilling miniscrews without surface treatment and with surface treatment. Both types presented a 1.4 or 1.2 mm diameter. Miniscrews were inserted between the first molar and second premolars or between the two premolars. The force applied to the screws was an elastic chain from the head of the miniscrews to a direct button applied on the canines. The success rate of each type of miniscrew was considered the primary outcome, and the association of success with demographical, clinical, and geometrical characteristics was investigated. Differences were tested by the generalised linear mixed effects model for the split-mouth design. Differences with a P-value < 0.05 were selected as significant. RANDOMISATION: A randomisation list was created for the mouth side assignment. BLINDING: The study was single blinded with regard to the statistical analysis. RESULTS: Thirty-nine miniscrews of the non-treated type and 39 miniscrews of the surface-treated type were inserted in 39 patients (23 female and 16 male, mean age: 15.55 ± 7.91) recruited between March 2018 and December 2020 with a split-mouth study design. The mean therapy duration was 9.3 months (SD = 1.31). No differences in failure rate were observed between miniscrew types. No serious harm was observed. CONCLUSIONS: The success rate of surface-treated and non-treated miniscrews showed no significant differences. REGISTRATION: This trial was not registered.

Influence of incisor position control on the mandibular response in growing patients with skeletal Class II malocclusion.

INTRODUCTION: This study aimed to test whether control in maxillary and mandibular incisor position, during treatment with an acrylic splint Herbst appliance, could influence the mandibular response in growing patients with skeletal Class II malocclusion. METHODS: The lateral cephalograms of 61 patients (mean age, 12.3 years; standard deviation, 1.6) with skeletal and dental Class II malocclusion were retrospectively analyzed both at baseline and after Herbst appliance removal, using a modified Pancherz cephalomeric analysis. Forty-five patients had received miniscrew in the mandibular arch to control mandibular incisor anchorage. In 21 patients, the maxillary incisors had been proclinated before starting the treatment for deepbite and maxillary incisor lingual inclination. All the patients were categorized a posteriori into 2 homogeneous groups, according to dental overjet reduction: 30 patients with dental overjet reduction (DR) and 31 patients without dental overjet reduction (NDR). RESULTS: Both groups presented a significant skeletal correction. However, the change was significantly greater in the NDR group than in the DR group (P <0.01). The mandibular bone base reached a median value of 4.0 mm (interquartile range, 2.5) in the NDR group vs 1.1 mm (interquartile range, 2.8) in the DR group (P <0.001). The 2 groups were also significantly different in terms of the positional change of maxillary incisor, which was proclinated in group NDR and lingualized in group DR (P <0.001). CONCLUSIONS: The results showed that dental control of overjet was beneficial to improve the effectiveness of Herbst treatment in increasing mandibular length in growing patients with skeletal Class II malocclusion.

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.

Herbst appliance anchored to miniscrews in the upper and lower arches vs standard Herbst: A pilot study.

INTRODUCTION: The aim of this pilot study was to present the preliminary results of Class II malocclusion treatment using a skeletally anchored Herbst appliance with miniscrews inserted in the maxillary and mandibular arches to improve anchorage control and skeletal effects. METHODS: The treatment group (TG) consisted of 13 patients (10 males [M], 3 females [F]; mean age of 12.8 years) with Class II Division 1 malocclusion who were treated with the Herbst appliance and miniscrews inserted in the maxillary and mandibular arches. They were compared with a control group (CG) of 13 patients (10 F, 3 M, mean age of 12.2 years) with Class II Division 1 malocclusion treated with the standard Herbst appliance without miniscrews. Lateral cephalograms were taken before and after Herbst treatment, and cephalometric analysis was performed. RESULTS: In the TG group SNB (°) increased by 2.9°, whereas in CG group SNB (°) increased by 1.1° (P = 0.017). ANB (°) decreased in both groups: -3.3° in the TG group vs -1.3° in the CG group (P = 0.014). Pg-OLp distance increased in both groups: 5.70 mm in the TG group and 0.8 mm in the CG group (P = 0.022). Mandibular incisors proclined 1.6° in the TG group and 3.7° in the CG group. CONCLUSIONS: Herbst treatment reinforced with 4 miniscrews (2 in each arch) increased the orthopedic effect of treatment in growing patients with Class II malocclusion.

Four TADs supported Herbst mechanics: A case report.

The Herbst appliance (HA) is considered an efficient method to treat class II malocclusion characterized by mandibular retrusion. Nevertheless, HA is although hampered by side effects reducing its therapeutic potentialities. The association between HA and TADs in the lower arch has proved to be very effective in controlling lower incisor flaring. This case report shows that the insertion of TADs in both arches offers a satisfactory control of the vertical dimension, by avoiding a maxillary clockwise inclination.

Comparison of complications in the conventional telescopic Herbst rod and tube and Manni telescopic Herbst: A retrospective clinical study.

OBJECTIVES: To compare the prevalence of clinical complications between two different telescopic Herbst systems: the conventional telescopic system, with traditional rod and tube (RMS), and the Manni telescopic Herbst appliance (MTH). MATERIALS AND METHODS: Ninety subjects treated with RMS were compared to 89 patients treated with MTH. All of the complications that occurred were reported, and percentages of prevalence were calculated. RESULTS: MTH showed a significantly lower percentage of reversible complications (that did not require appliance removal) when compared to the reversible complications during RMS treatment (20.2% vs 51.1%). No statistically significant differences were found between RMS and MTH regarding irreversible complications (that required appliance removal and full re-make). All of the irreversible complications occurred after reversible complications in the RMS group, while most of the irreversible complications in the MTH group occurred without any previous reversible complication. CONCLUSIONS: MTH exhibited a smaller number of clinical complications during Class II skeletal malocclusion therapy.

Bone-anchored intermaxillary elastics in an asymmetric Class II malocclusion: A case report.

PURPOSE: A 13-year-old male patient, presenting a Class II, division 1 malocclusion and crowding was treated by an innovative technique. METHODS: After rapid palatal expansion by a Hyrax appliance, the teeth were bonded with straightwire brackets. Two miniscrews were inserted, one per side, in the mandibular buccal bone between the roots of the mandibular first molar and the second premolar. On the right side, the miniscrew implant was connected to the hook clamped on a 0.021×0.028″ SS wire with a twisted SS ligature in order to maintain the inclination of the frontal incisors during the Class II mechanics. On the left side, where the Class II relationship was more marked, intermaxillary elastics were applied from the upper left hook clamped on the archwire to the lower first molar and a power chain (100g) was stretched from the lower left hook to the miniscrew implant. Class II correction was accomplished using sequential Class II elastics of progressive strength coupled with rectangular stainless steel wires. RESULTS: After 22 months of active treatment, the results were balanced facial esthetics and a good occlusion. CONCLUSIONS: This dual anchorage set-up of Class II elastics reinforced with TADs produced protrusive action on the mandible with minimal side effects and with no significant change in the vertical dimension during the sagittal correction of the Class II malocclusion.