Growth-related differences in maximum laterotrusion and retrusion between children and adults

Evaluation of mandibular motion in adolescents with skeletal class II division 1 malocclusion during mandibular advancement using clear functional aligners: a prospective study

BACKGROUND

This study aimed to evaluate the characteristics of mandibular protrusive condylar trajectory in adolescents with skeletal Class II Division 1 malocclusion and the changes of condylar trajectory during mandibular advancement (MA) treatment using clear functional aligners.

METHODS

This prospective study consisted of a cross-sectional study and a longitudinal study. In cross-sectional study, sixty-one adolescents were divided into two groups: Class I (n = 30) and Class II Division 1 (n = 31). The condylar trajectory was measured and compared using the Mann-Whitney U test. The longitudinal study was the MA treatment group using clear functional aligner and consisted of 16 participants from Class II Division 1group. The condylar trajectory was collected at three-time points: pre-treatment (T1), during MA treatment at approximately 3 months (T2, 105.6 days average), and at the end of MA treatment (T3, 237.6 days average). The changes at T1, T2, and T3, as well as the symmetry between the left and right condyles across all groups, were examined using the Wilcoxon paired test.

RESULTS

A greater increase in the anteroposterior displacement and space displacement during protrusive movements was observed in the Class II Division 1 group compared with that in the Class I group, with a large difference being observed in the left and right condylar movements. The condylar anteroposterior displacement and space displacement decreased significantly at T2 and increased significantly at T3; however, no significant difference was observed between T1 and T3. A significant difference was observed between the condylar movement on the left and right sides at T1; however, no significant difference was observed at T2 and T3.

CONCLUSIONS

Adolescents with Class II Division 1 malocclusion had higher protrusive capacity than those with Class I. Moreover, their left and right condylar motion was more asymmetric. The range of condyle motion decreased first and then increased during MA therapy, and the left and right condyle movement became more symmetrical, which may be the adaptive response of neuromuscular function to the changes in jaw position.

Evaluation of Changes in Condylar Cartilage Thickness Using MRI and Ultrasound Imaging in Patients Treated by Mandibular Advancement With Myofunctional Appliance: An In-Vivo Pilot Study

Introduction

The changes occurring due to growth modulation of the condylar cartilage act as an important mechanism for mandibular advancement using myofunctional appliance therapy. So this study aims to evaluate the condylar cartilage thickness by using MRI and USG in patients undergoing myofunctional appliance therapy for mandibular advancement with the null hypothesis being that there are no changes seen in the thickness of condylar cartilage in growing children.

Materials and methods

A prospective evaluation of samples having skeletal Class-II malocclusion ranging between cervical vertebral maturation index (CVMI) stage II and III, requiring twin block functional therapy was performed. Ten patients were selected randomly who underwent MRI and USG in the open and close positions for the evaluation of condylar cartilage thickness and the dimensional changes in the width of the right and left condyle in mm at T0 and T1.

Result

There was no statistically significant difference between the values interpreted by MRI or USG imaging when compared at T0 and T1 and in the open and closed mouth on the left and right sides. At T0, the mean thickness noted was 0.49 mm and 0.48 mm during opening and closing on the left side and 0.52 mm in both positions on the right side. At T1, the mean thickness noted was 0.8 and 0.79mm during opening and closing on the left side, whereas it was 0.81 mm in both positions on the right side.

Conclusion

The condylar cartilage thickness increases significantly after twin block therapy suggestive of mandibular growth in skeletal class II malocclusion. It can be inferred that both MRI and USG carry equal diagnostic interpretation, as there was no statistically significant difference between the two imaging modalities.

Prevalence of diagnosed temporomandibular disorders among Saudi Arabian children and adolescents

Background

Studies have indicated that the prevalence of symptoms and signs of temporomandibular disorders (TMD) are rare early in childhood, but become more prevalent in adolescents and adulthood. To our knowledge, no study has investigated the prevalence of TMD-diagnoses in children in the general population. The aim was thus to investigate the prevalence of TMD-diagnoses among children and adolescents in the general population using the Research Diagnostic Criteria for TMD (RDC/TMD).

Methods

The current cross-sectional study consisted of 456 children and adolescents, aged between 10 and 18, randomly enrolled from 10 boy’s- and 10 girl’s- schools in Jeddah. The participants first answered two validated questions about TMD-pain, followed by a clinical examination according to RDC/TMD.

Results

One hundred twenty-four participants (27.2 %) were diagnosed with at least one TMD-diagnosis. Myofascial pain was the most common diagnosis (15 %) followed by disc displacement with reduction, arthralgia, myofascial pain with limited mouth opening and osteoarthrosis. Children diagnosed with myofascial pain more often reported orofacial pain, headache and tooth clenching (p < 0.05), whereas children with arthralgia more often reported orofacial pain and tooth grinding than those without a TMD-diagnosis (p < 0.05). Only 18 % of the subjects in the TMD group had sought a dentist or physician for their pain.

Conclusion

TMD was common among children and adolescents in Saudi Arabia. Self-reported orofacial pain and headache as well as bruxism were associated with a TMD-pain diagnosis and disc displacement. A surprisingly low percentage of children and adolescents sought treatment by a dentist or physician for their pains.

Determinação da amplitude dos movimentos mandibulares em crianças do estado da Bahia

RESUMO Objetivo: determinar a amplitude dos movimentos mandibulares de crianças brasileiras, do Estado da Bahia, de acordo com a idade, gênero e altura. Métodos: participaram do estudo 181 escolares de 8 a 12 anos, todos assintomáticos para Disfunção Temporomandibular, segundo o Research Diagnostic Criteria/ Temporomandibular Disorders, RDC/TMD. Realizaram-se as medidas da amplitude da abertura bucal máxima, lateralidade direita, lateralidade esquerda e protrusão. As medidas foram feitas com o paquímetro digital Starret Serie 799. A análise estatística foi STAT versão 11. Aplicou-se a regressão multivariada das medidas obtidas destacando-se gênero, idade e altura como interferentes para amplitude dos movimentos mandibulares (P˂0,05). Resultados: 1. masculino/altura (131,45 ≥ 146,05cm); abertura bucal máxima 48,07 a 50,29mm; lateralidade direita 8,19 a 8,55mm; lateralidade esquerda 7,88 a 8,51mm e protrusão 6,72 a 8,30mm. 2. feminino/altura (129,68 ≥ 142,64cm): abertura bucal máxima 47,15 a 50,71mm; lateralidade direita 7,27 a 8,58mm; lateralidade esquerda 7,66 a 8,21mm e protrusão 6,51 a 7,22mm. 3. masculino /idade: abertura bucal máxima 47,52 a 50,84mm; lateralidade direita 7,76 a 8,85mm; lateralidade esquerda 7,93 a 9,36mm; protrusão 6,60 a 8,50mm. 4. feminino/idade: abertura bucal máxima 47,16 a 50,7mm; lateralidade direita 7,53 a 8,60mm; lateralidade esquerda 7,42 a 8,30mm; protrusão 6,41 a 7,48mm. Conclusão: os valores da amplitude dos movimentos mandibulares de acordo com idade, gênero e altura, para a população estudada, foram descritos e podem contribuir como um referencial que pode auxiliar na avaliação funcional do sistema mastigatório.

Correlation of condylar kinematics in children with gender, facial type and weight

OBJECTIVE

The aim of the study has been to describe the normal range of mandibular movements and condylar kinematics in children as well as to test the null hypothesis that these variables are not associated with gender, facial type and weight.

MATERIALS AND METHODS

The sample was comprised of 92 healthy children (7.2-10.6 years old) and 40 adult controls (18-34.7 years old). Examinations included the maximal mouth opening capacity and laterotrusion to the right and to the left. The condylar path inclination angle was calculated at 3mm and 5mm protrusion of the mandible. Kinematic variables were registered using the ultrasonic JMA system.

RESULTS

Maximal mouth opening capacity averaged 46.73 mm for the children and 53.53 mm for the adults. The mean values of the lateral movements were 9.36 mm to the right and 9.62 mm to the left for the boys, and 9.91 mm and 9.68 mm for the girls, respectively. Mean condylar path inclination in the children was 36.5° (right) and 36.2° (left) at 3mm of protrusive movement, and 34.3° (right) and 34.0° (left) at 5mm of protrusive movement. Associations of the kinematic variables with gender, weight, or facial type were insignificant.

CONCLUSION

Younger school children have not yet reached the maximum mouth-opening capacity. Correlation analysis suggests some weak, but insignificant associations of gender, facial type and weight with mouth opening, laterotrusion and the condylar path inclination angle. The null hypothesis was not rejected.

Variations in the inclination of the condylar path in children and adults

OBJECTIVE

To test the null hypothesis that there are no differences between children and adults in the condylar path inclination angle on the right and left sides.

MATERIALS AND METHODS

A group of 80 children aged 6 to 10 years (subgroups I through V, according to chronologic age) was compared with an adult group with regard to the condylar path inclination angle (CPIA) on the right and left sides. The CPIA was measured using the ultrasonic JMA-System for registration.

RESULTS

During development of the temporomandibular joint the condylar path inclination angle increased with age in the subgroups of children. A significant difference was found in the CPIA between the groups of adults and children. In the group with the oldest children (mean age: 10.3 years) the condylar path inclination angle had reached 81.87% on the right side and 78.85% on the left side compared with the adult group at a 5 mm protrusive path. In the pooled group of children the CPIA amounted to 73.08% on the right side and 72.13% on the left side compared with the values for the adults. No significant difference was found between the right and left CPIA in any group.

CONCLUSION

The hypothesis is rejected. The CPIA on the right and left sides increased with age in the group of children and was significantly smaller in the group of children compared with the group of adults.