Evaluation of the anterior dentoalveolar relationship in skeletal Class III malocclusion patients with different vertical facial patterns using cone-beam computed tomography.

OBJECTIVES: To measure and compare labiolingual inclinations of the teeth and alveolar bone and the anterior dentoalveolar inclination in patients with skeletal Class III malocclusions with different vertical facial patterns using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: Based on the inclusion and exclusion criteria, 84 CBCT images of patients with untreated skeletal Class III malocclusion were selected. There were 28 patients each in the hypo-, normo-, and hyperdivergent groups. The labiolingual inclinations of the teeth, the corresponding alveolar bone, and the anterior dentoalveolar inclinations were measured and analyzed statistically. RESULTS: The inclinations of the mandibular canine and corresponding alveolar bone were smaller in the hypodivergent group than in the hyperdivergent group. The inclination of the alveolar bone and the maxillary dentoalveolar inclination were smaller in the hyperdivergent group than in the hypodivergent group. CONCLUSIONS: There were differences in the inclination of the teeth, corresponding alveolar bone, and dentoalveolar inclinations at different positions among skeletal Class III patients with different vertical facial patterns. The roots were generally located on the labial side of the alveolar bone.

Dehiscence and fenestration of skeletal Class III malocclusions with different vertical growth patterns in the anterior region: A cone-beam computed tomography study.

INTRODUCTION: This study aimed to evaluate the incidence and distribution of alveolar bone dehiscence and fenestration in skeletal Class III malocclusions with different vertical growth patterns in the anterior region using cone-beam computed tomography (CBCT). METHODS: In this retrospective study, 84 patients with skeletal Class III malocclusions who underwent CBCT were selected. This study included 28 patients with hypodivergence (mean age, 22.9 ± 3.9 years), 28 with normodivergence (mean age, 21.0 ± 3.0 years), and 28 with hyperdivergence (mean age, 21.0 ± 3.7 years). Teeth in the anterior region were examined using CBCT to detect dehiscence and fenestration. The incidences of dehiscence and fenestration in the anterior teeth region were recorded, and statistical analysis was conducted using SPSS software (version 25.0, IBM, Armonk, NY). RESULTS: Among the patients with skeletal Class III malocclusions, dehiscence and fenestration were prone to occur in the mandible. Dehiscence and fenestration were more prevalent in patients with hyperdivergence compared with in patients with hypodivergence and normodivergence. CONCLUSIONS: Dehiscence and fenestration are prevalent among patients with skeletal Class III malocclusion. Furthermore, the occurrence of alveolar bone defects is higher in patients with hyperdivergence.

Analysis of dental and basal bone arch form correlations in skeletal Class â ¡ malocclusion.

INTRODUCTION: This study aimed to establish mathematical equations to describe the dental and basal arch forms in skeletal Class II malocclusion and to investigate correlations between these forms to facilitate clinical diagnosis and treatment design. METHODS: Cone-beam computed tomography images of 60 patients (30 each with skeletal Class II malocclusion and normal occlusion) were subjected to 3-dimensional volume rendering, image reconstruction, and measurement. Using a computer program written in Java on the Eclipse platform (Eclipse Foundation, Ottawa, Canada), a beta function was used to establish mathematical models of dental and basal bone arch forms, and model-fitting was performed. RESULTS: A mathematical model was developed to describe the dental and basal arch forms in skeletal Class II malocclusion. The maxillary and mandibular dental arch lengths were significantly longer in skeletal Class II malocclusion than in normal occlusion, whereas the width of the maxillary molar segment was smaller. The maxillary molar and mandibular intercranial segments in the basal arch were significantly longer in skeletal Class II malocclusion than in normal occlusion, whereas the mandibular intercranial segment width was smaller. CONCLUSIONS: The dental arch and basal bone arch forms in the maxilla and mandible follow individual curves, described by a beta function. In skeletal Class II malocclusion, the dental and basal arches are discrepant in horizontal and anteroposterior dimensions, which should be considered during orthodontic treatment planning to improve arch matching.

[The characteristics of the arch form of skeletal Class II malocclusion].

OBJECTIVE: To study the characteristics of the arch form of skeletal Class III malocclusion and provide references for diagnosis and treatment plan. METHODS: 7 indexes in dental casts of 47 patients with skeletal Class III malocclusion and 50 individuals with normal occlusion were measured respectively. And differences between corresponding upper and lower measurements were calculated. Independent samples t-test was employed for comparing between the two groups by SPSS 17.0. RESULTS: Compared with normal occlusion sample, Class III malocclusion group had smaller anterior segment lengths and larger canine angles (P<0.05). Differences between upper and lower first premolar widths were larger in males with skeletal Class III malocclusion. And differences between upper and lower anterior segment lengths were smaller in males with skeletal Class III malocclusion (P<0.05). CONCLUSION: Arch widths of patients with skeletal Class III malocclusion are basically normal. The lengths of anterior segment are smaller and the anterior arch forms are straighter.