Modified Thurow appliance: a clinical alternative for correcting skeletal open bite

Dentoskeletal effects of the maxillary splint headgear in the early correction of Class II malocclusion

Background

To compare dentoskeletal changes produced by the maxillary splint headgear and cervical headgear appliance during the early phase of Class II treatment, specially the initial overjet and upper incisors position.

Subjects and methods

In this retrospective study, 28 Class II patients treated with the maxillary splint headgear (MSG, mean age 10.1 ± 1.9 years) and 28 Class II patients treated with cervical headgear (CHG, mean age 9.5 ± 1.9 years) were evaluated before and after treatment. Statistical comparisons between the two groups for cephalometric measurements at T1 and for T2-T1 changes were performed by means of independent sample t tests.

Results

The MSG showed a significantly greater reduction of the overjet in comparison to the CHG (− 2.4 mm and − 0.7 mm, respectively) and a significantly greater maxillary incisor uprighting (− 1.8 mm and 0.4 mm, respectively). In the MSG, overjet correction was due mainly to mandibular advancement (3.5 mm), while the correction of molar relationship (3.9 mm) was 64% skeletal and 36% dentoalveolar. In the CHG, the overjet correction was also more skeletal, due to mandibular growth (1.8 mm), while correction of molar relationship (3.5 mm) was 63% dentoalveolar and 37% skeletal.

Conclusions

Both groups showed favorable skeletal mandibular changes, which was more significant in the MSG. Regarding tooth movement, the maxillary splint headgear was more effective in uprighting upper incisors and reducing the overjet than cervical headgear appliance.

Diagnosis and Management of a Unilateral Posterior Open Bite Using a Temporary Anchorage Device (TAD): Case Report and Review of the Literature

This report describes the diagnosis and successful treatment of a unilateral posterior open bite (POB) in a 15-year-old Caucasian boy. Simple mechanics were used to rule out ankylosis of left posterior teeth as the etiological factor of the POB. Thereafter, the same mechanics were continued to expand the unilateral constricted maxilla, to create a space, and to close POB. Sectional biomechanics were applied to avoid undesirable tooth movements. Then, continuous arch wires were employed to coordinate arches and to achieve treatment objectives.

Photoelastic analysis of tension distribution in different orthodontic approaches for closing anterior open bites

BACKGROUND

This study aims to evaluate tension distribution in the anterior region of the mandible during two orthodontic mechanical approaches to treat anterior open bite.

METHODS

It was an in-vitro experimental study, that analyzed 5 models of photoelastic resin, simulating a lower dental arch. The anterior teeth underwent orthodontic forces of the Blue Elgiloy® 0.016" x 0.022" (MEAW technique) and Gummetal® 0.018"x 0.022" (GEAW technique) archwires. Tension distribution was assessed on three different points in the lower dental midline and was measured using a reflection polariscope. The archwires were evaluated with and without anterior elastic bands (6 oz, 170 g) installed between lateral incisors and lower canines, as recommended for anterior open bite.

RESULTS

The highest magnitudes of tension generated by the archwires were observed in the cervical regions of the teeth (on average 50% higher than those at the most apical point) regardless of the technique used. Comparatively, the GEAW technique showed significantly (P<0.05) lower tension values (16 MPa) than the MEAW technique using Blue Elgiloy (24 MPa).

CONCLUSIONS

The GEAW technique showed a more favorable tension distribution pattern than the MEAW approach. The use of elastic bands improved tension distribution, regardless of the technique. The results also suggest that the use of anterior elastic bands in both techniques reduced the tensions released by the intrusive forces generated by the archwires.

Anteroposterior and vertical changes in skeletal class II patients treated with modified Thurow appliance

The aim of this study was to evaluate the post-treatment anteroposterior and vertical alterations in skeletal Class II malocclusion with different maxillary patterns in patients treated with modified Thurow appliance. Forty-five patients (22 girls and 23 boys) with skeletal Class II and angle SN.GoGn ≤ 35 and different maxillary patterns (n = 15), as follows: retrusive (SNA<80°), normal (SNA = 80°- 84°) or protrusive (SNA>84°) maxilla; mean age 9 years at pre-treatment (T1) and 9 years and 10 months at post-treatment (T2), were treated with modified Thurow cervical traction appliance, with expander screw and extraoral face bow with 10° to 20° fold in relation to the intraoral arch. Force of 500 gf was applied and use for 12 to 14 h/day, with fortnightly adjustments. Analysis of variance ANOVA followed by post-hoc Tukey and Kruskal-Wallis test, followed by Mann-Whitney were used (α = 5%). In changes obtained from stage T1 to T2, no statistically significant differences were found among the groups Protrusive, normal and retrusive maxilla for the variables SNB, SN.GoGn, 1.NA, overjet, overbite and Class II discrepancy (right and left) (p>0.05). Angular measurements SNA and ANB in the protrusive maxilla group were significantly greater than in the normal and retrusive maxilla groups (p<0.01). However, in the normal maxilla group these values did not differ significantly from those of the retrusive maxilla group (p>0.05). Within the limits of this study, it may be concluded that the modified Thurow cervical traction appliance was efficient for the correction of skeletal Class II irrespective of the maxillary pattern. The mandible had no significant rotation during treatment.

Open bite: diagnosis, treatment and stability

Open bite has fascinated Orthodontics due to the difficulties regarding its treatment and maintenance of results. This anomaly has distinct characteristics that, in addition to the complexity of multiple etiological factors, have aesthetic and functional consequences. Within this etiological context, several types of mechanics have been used in open bite treatment, such as palatal crib, orthopedic forces, occlusal adjustment, orthodontic camouflage with or without extraction, orthodontic intervention using mini-implants or mini-plates, and even orthognathic surgery. An accurate diagnosis and etiological determination are always the best guides to establish the objectives and the ideal treatment plan for such a malocclusion. This report describes two cases of open bite. At the end of the treatment, both patients had their canines and molars in Class I occlusion, normal overjet and overbite, and stability during the posttreatment period.

Dental and skeletal components of Class II open bite treatment with a modified Thurow appliance

INTRODUCTION

Due to the lack of studies that distinguish between dentoalveolar and basal changes caused by the Thurow appliance, this clinical study, carried out by the School of Dentistry--State University of São Paulo/Araraquara, aimed at assessing the dental and skeletal changes induced by modified Thurow appliance.

METHODS

The sample included an experimental group comprising 13 subjects aged between 7 and 10 years old, with Class II malocclusion and anterior open bite, and a control group comprising 22 subjects similar in age, sex and mandibular plane angle. Maxillary/mandibular, horizontal/vertical, dental/skeletal movements (ANS, PNS, U1, U6, Co, Go, Pog, L1, L6) were assessed, based on 14 landmarks, 8 angles (S-N-ANS, SNA, PPA, S-N-Pog, SNB, MPA, PP/MPA, ANB) and 3 linear measures (N-Me, ANS-Me, S-Go).

RESULTS

Treatment caused significantly greater angle decrease between the palatal and the mandibular plane on the experimental group, primarily due to an increase in the palatal plane angle. ANB, SNA and S-N-ANS angles significantly decreased more in patients from the experimental group. PNS was superiorly remodeled. Lower face height (ANS-Me) decreased in the experimental group and increased in the control group.

CONCLUSIONS

The modified Thurow appliance controlled vertical and horizontal displacements of the maxilla, rotated the maxilla and improved open bite malocclusion, decreasing lower facial height.

Combining traditional techniques to correct anterior open bite and posterior crossbite

The treatment of anterior open bite often requires the use of skeletal anchorage to prevent excessive eruption of the posterior teeth and consequent downward rotation of the mandible. However, this procedure might not always be accomplished. This article reports the successful treatment of an anterior open bite and a posterior crossbite in a young boy, combining traditional techniques and involving high-pull maxillary traction to help growth to correct the skeletal Class II malocclusion without skeletal anchorage. The vertical dentoalveolar contribution of maxillary growth was also favorable to close the bite, whereas cross-elastics corrected the axial inclination of the mandibular posterior teeth, eliminating the inverted posterior crossbite. The open bite was completely closed with edgewise appliances, which also achieved normal overjet, intercuspation, and incisor exposure on smiling. Traditional mechanics for the treatment of open bite and crossbite remain a useful alternative when patients do not accept skeletal anchorage.

Má oclusão Classe I de Angle, com mordida aberta anterior, tratada com extração de dentes permanentes

A mordida aberta é uma anomalia com características distintas que, além da complexidade dos múltiplos fatores etiológicos, traz consequências estéticas e funcionais. Muitas alternativas têm sido utilizadas em seu tratamento, entre elas a grade palatina, forças ortopédicas, ajuste oclusal, camuflagem com ou sem exodontias, mini-implantes ou miniplacas e cirurgia ortognática. O diagnóstico preciso e a determinação da etiologia permitem estabelecer os objetivos e o plano de tratamento ideal para essa má oclusão. O presente relato descreve o tratamento de uma má oclusão Classe I de Angle, com padrão esquelético de Classe II e mordida aberta anterior, realizado em duas fases e que foi apresentado à diretoria do Board Brasileiro de Ortodontia e Ortopedia Facial (BBO), representando a categoria 2, como parte dos requisitos para a obtenção do título de Diplomado pelo BBO.