Dentofacial Factors Associated With Upper And Lower Incisor Bony Support

Part ?:Dentofacial traits in association with lower incisor alveolar cancellous bone thickness:a multiple regression analysisObjective:To identify dentofacial anatomic traits associated with lower incisor cancellous bone thickness (LICBT), and then to assess their separate contributions and their combined contributions to the variation of LICBT.Materials and Methods:A consecutive sample of cone beam computed tomography (CBCT) data taken in a university hospital with a same setting was retrospectively reviewed. Among them CBCT data of 252 eligible subjects were reconstructed and measured for LICBT, facial traits and mandibular symphyseal traits. A backward multiple linear regression was employed to explore the association between LICBT and seven representative dentofacial traits.Results:Four dentofacial traits (vertical facial pattern, transverse jaw relationship, lower incisor cervical diameter and mandibular symphyseal width) were identified as significantly associated with lower incisor cancellous bone thickness. The combination of these four factors could predict 64.3% of variations in lower incisor cancellous bone thickness (adjusted R2=0.643). Further comparison of LICBT among different transverse jaw relationships suggested that LICBT of normal (5.94 ± 1.58 mm) group and inferior convergent (5.38±1.32 mm) group were significantly larger than that of crossbite group (4.34 ± 1.27 mm) and superior convergent (4.53 ± 1.67 mm) group.Conclusions:The bony support of lower incisors is significantly associated with several dentofacial traits. Reduced lower incisor bony support was statistically associated with the increased vertical facial pattern, the transverse jaw discrepancy, the thinner mandibular symphyseal width and the smaller lower incisor cervical diameter.Part ?:Dentofacial traits in association with upper incisor alveolar cancellous bone thickness:a multiple regression analysisObjective:To identify dentofacial anatomic traits associated with upper incisor cancellous bone thickness (UICBT), and then to assess their separate contributions and their combined contributions to the variation of UICBT.Materials and Methods:A consecutive sample of cone beam computed tomography data taken in a university hospital with a same setting was retrospectively reviewed. Among them CBCT data of 252 eligible subjects were reconstructed and measured for UICBT, facial traits and upper incisor traits. A backward multiple linear regression was employed to explore the association between UICBT and five representative dentofacial traits.Results:Only vertical facial pattern were identified as being significantly associated with lower incisor cancellous bone thickness. This factor could explain 18.7% of variation in upper incisor cancellous bone thickness (adjusted R2=0.187).Conclusions:The bony support of upper incisors is significantly associated with vertical facial pattern. The more increased vertical facial pattern seems more likely to be associated thiner upper incisor bony support, and vice versa.