Factors affecting molar root and periodontal hard tissue changes after orthodontic anterior molar closure of missing tooth spaces explored based on CBCT three-dimensional reconstruction

AbstractOBJECTIVE: To correlate the molar teeth and their periodontal conditions after orthodontic anterior removal of the molars to close the gap of missing teeth and to provide risk factor analysis and prognostic assessment for the treatment of such cases.METHODS: Twenty-six orthodontic patients (5 males and 21 females) with a total of 42 teeth were selected to undergo full-mouth orthodontic treatment due to the absence of the first/second molar and the molar bone volume was recorded by cone-beam computed tomography (CBCT) scanning before (T0) and after (T1) the treatment, and the root volume and the bone volume of the molar teeth were calculated by three-dimensional reconstruction of the CBCT. Afterwards, the correlation analysis was performed between the molar root volume change and bone volume condition and age, gender, density, width, height of the alveolar bone in the edentulous area, edentulous gap and root condition.RESULTS: The amount of alveolar bone loss and root resorption in the anteriorly displaced molars after treatment was less than 20%. There was a statistically significant correlation between age and pre-treatment periodontal condition, distal mesial and buccal bone loss; there was a statistically significant correlation between alveolar bone width in the edentulous area and pre-treatment periodontal condition and buccal bone loss; there was a statistically significant correlation between edentulous gap and post-treatment periodontal changes and buccal bone loss; there was a statistically significant correlation between gender and lingual bone loss; and there was a statistically significant correlation between root resorption and pre-treatment There was a statistically significant correlation between the width of the alveolar bone in the edentulous area; there was no statistically significant correlation between the density and height of the alveolar bone in the edentulous area and the periodontal condition.CONCLUSION: Orthodontic closure of the missing tooth gap by orthodontic interproximal molar removals does not result in severe root resorption, periodontal destruction, or loss of molar bone height, and there is a possibility of improvement in periodontal condition and an increase in bone height. Closure of the missing gap by orthodontic proximal-medial movement of the molars is a feasible method with a predictable prognosis.