Customized maxillary incisor position relative to dentoskeletal and soft tissue patterns in Chinese women: A retrospective study

Abstract

Objective: To provide reliable prediction models based on dentoskeletal and soft tissue variables for customizing maxillary incisor positions and to optimize digitalized orthodontic treatment planning.

Methods: This study included 244 Chinese women (age, 18-40 years old) with esthetic profiles after orthodontic treatment with fixed appliances (133 in group I: 1° ≤ The angle between the nasion [N]-A point [A] plane and the N-B point [B] plane [ANB] ≤ 4°; 111 in group II: 4° < ANB ≤ 7°). Dental, skeletal, and soft tissue measurements were performed on lateral cephalograms of the participants. Correlation and multiple linear regression analyses were used to determine the influence of dentoskeletal and soft tissue variables on maxillary incisor position.

Results: The ideal anteroposterior position of the maxillary incisor varied between sagittal skeletal patterns. The position of the maxillary incisor correlated with the sagittal discrepancy between the maxilla and the mandible (ANB), protrusion of the midface, nasal tip projection, development of the chin, and inclination of both the maxillary and mandibular incisors. Distance from the maxillary central incisor to nasion-pogonion plane predicted using multiple linear regression analysis was accurate and could be a practical measurement in orthodontic treatment planning.

Conclusions: Instead of using an average value or norm, orthodontists should customize a patient's ideal maxillary incisor position using dentoskeletal and soft tissue evaluations.

Keywords: Cephalometrics; Customized maxillary incisor position; Dentoskeletal and soft tissue patterns; Mathematical approach.

Figure 1

Reference planes and landmarks used in this study. Reference planes: Frankfort horizontal plane (FH), a plane passing through the porion and orbitale; Esthetic plane (EP), a plane passing through the pronasale and tangent to the chin; Mandibular plane (MP), a plane passing through the menton and tangent to the posterior portion of the lower border of the mandible; Np, a line passing through the nasion and perpendicular to the FH plane; Ap, a line passing through the A point and perpendicular to the FH plane; G’ vert, a line passing through the glabella and perpendicular to the FH plane; Sn vert, a line passing through the subnasale and perpendicular to the FH plane. Landmarks: S, sella; N, nation; Or, orbitale; P, porion; Go, gonion; A, A point; B, B point; Pog, pogonion; Me, menton; ANS, anterior nasal spine; PNS, posterior nasal spine; Prn, pronasale; Sn, subnasale; Ls, labrale superius; Li, labrale inferius; G’, glabella; Pog’, pogonion of soft tissue; Me’, menton of soft tissue.