Relationship between mandibular dental and basal bone arch forms for severe skeletal Class III patients

Introduction: The purpose of this study was to analyze the relationship between the mandibular dental and basal bone arch forms for severe skeletal Class III patients by using 3-dimensional digital models. Methods: Thirty-three virtual pretreatment mandibular models were created with a laser scanning system. The most prominent part of the center of the clinical crown where an orthodontic bracket would be placed (FA) and the most prominent point on the soft-tissue ridge at the mucogingival junction (WALA) were used to represent the dental and basal arch forms, respectively. Results: A moderate-to-high correlation between the FA and WALA curves was found, especially in the canine (r = 0.61) and molar (r = 0.91) areas. The WALA curve's radius of curvature in the anterior teeth areas was greater than that of the FA curve (WALA, 22.47; FA, 18.18). In the canine and molar areas, the coefficients of variation of FA (6.70%, 6.01%, 15.30%, and 9.97%) were greater than those of WALA (5.42%, 3.88%, 8.53%, and 7.22%). For the FA and WALA points, the coefficients of variation of the canine area were greater than those of the molar area. Conclusions: Both curves were individualized. A moderate-to-high correlation was found between the dental and basal bone arch forms. Compared with the WALA points, the FA points are located more lingually. The individual differences were found to be significantly greater in the canine region.