Abstract
ObjectiveThis Cross-sectional study used cone-beam computed tomography (CBCT) to evaluate the difference in the alveolar bone of the anterior teeth between high-angle adults with severe skeletal Class II malocclusions and Class III malocclusions.Materials and methodsThe CBCT archives from 62 high-angle adults were selected from patients of the Stomatology Hospital of Peking University between October 2017 to January 2018. The 62 high-angle adult subjects were divided into the following 2 groups based on their sagittal jaw relationships: severe skeletal Class II and severe skeletal Class III. Vertical bone level (VBL), alveolar bone area (ABA), and thickness of alveolar bone were measured at 2 mm, 4 mm, and 6 mm below and above to the cemento-enamel junction (CEJ) level, as well as at the apical level. Then, independent samples t-test were conducted for statistical comparisons.ResultsIn the maxillary incisors, the labial VBL was smaller in the patients in skeletal Class III group than those in skeletal Class II group (P<0.05). On the labial side, the ABA was significantly thinner in patients in skeletal Class II group than those in skeletal Class III group, especially in terms of the maxillary central incisors’ ABA at 4 mm and 6 mm above the CEJ level (P<0.05), in terms of apical ABA and total ABA of the maxillary lateral incisors (P<0.05). The alveolar bone thickness around maxillary lateral incisors was significantly thinner in patients of skeletal Class II than that of patients of skeletal Class III, especially regarding the apical level on the labial side (P<0.05). The ABA of the mandibular alveolar bone in the area of the lower anterior teeth was significantly thinner in patients in skeletal Class III group than those in skeletal Class II group, especially in terms of apical ABA, total ABA on the labial and lingual sides, and ABA at 6 mm below the CEJ level on the lingual side (P<0.05). In the mandibular lateral incisors, the alveolar bone thickness was significantly thinner in patients in skeletal Class III group than it was in patients in skeletal Class II group, especially regarding the apical level on the lingual side (P<0.05).ConclusionsThe ABA and the alveolar bone thickness of the mandibular anterior teeth were significantly thinner in the severe high-angle group of skeletal Class III adult patients than in the sample of severe high-angle skeletal Class II adult cases. Our study firstly revealed that the roots of the maxillary central and lateral incisors were placed more labially in the subjects of severe high-angle skeletal Class II than in those of severe high-angle skeletal Class III, especially in the lateral incisors.
Highlights
Skeletal Class II and skeletal Class III malocclusions, which affect the patient’s facial appearance, masticatory function and mental health, are the most common malocclusions in orthodontic patients
The alveolar bone area (ABA) was significantly thinner in patients in skeletal Class II group than those in skeletal Class III group, especially in terms of the maxillary central incisors’ ABA at 4 mm and 6 mm above the cemento-enamel junction (CEJ) level (P
The ABA of the mandibular alveolar bone in the area of the lower anterior teeth was significantly thinner in patients in skeletal Class III group than those
Summary
Skeletal Class II and skeletal Class III malocclusions, which affect the patient’s facial appearance, masticatory function and mental health, are the most common malocclusions in orthodontic patients. A delineation of the limits of orthodontic tooth movement prior to the start of treatment would be extremely beneficial whether using orthodontic therapy alone or using a combination of orthodontic and orthognathic therapy. Alveolar bone remodeling is affected by the orthodontic force, the morphology of alveolar bone and the balance of the muscles of lip and tongue [1,2]. Excessive retraction or proclination of the anterior teeth may result in iatrogenic sequelae, such as root absorption, alveolar bone loss, dehiscence, fenestration, and gingival recession [3,4]. Morphometric evaluation of alveolar bone of anterior teeth might be a good model to explain the therapeutic limitation of orthodontic tooth movement. The advent of cone-beam computed tomography (CBCT) has allowed more extensive studies evaluating alveolar bone morphology in the anterior region. CBCT has been found to be valuable in that it is more accurate for assessing bony architecture or quantifying bone volume than traditional radiographic images such as panoramic or periapical views [5,6]
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