Purpose: This study aimed at measuring the differences between the two-dimensional (2D) and three-dimensional (3D) radiographic boundaries for molar distalization, and their correlations for the amount of maxillary molar distalization.
Patients and Methods: A total of 250 consecutive adult patients were retrospectively reviewed. All the enrolled patients possessed Angle Class III malocclusion with moderate maxillary crowding and suitable for camouflage treatment. The spatial differences between the 2D and 3D radiographic boundaries were compared and measured. The correlation among the range of the distalization boundary and studied clinical variables were assessed by Pearson correlation and the linear regression to determine the correlation between the 2D and 3D assessments.
Results: There were 21 patients (42 segments) with Angle Class III malocclusion and moderate maxillary dental crowding included for study. According to 3D images, the average sagittal distance from the posterior nasal spine (PNSct) to the posterior border of the maxillary tuberosity (TU) was 1.80 ± 1.81 mm. The shortest distance from the distal border of the TU to the most distal root surface of the maxillary second molar (CT-R) was 5.24 ± 2.26 mm. The corresponding cephalometric distance from the distal height of contour of the maxillary second molar to the PNSceph (Ceph-C) was 5.98 ± 2.62 mm. The 2D measurements were significantly and positively correlated with the 3D measurements with the equation CT-R = 1.606 + (0.608 × Ceph-C). The range of the distalization boundary was not associated with clinical variables including age, Frankfort mandibular plane angle, point A–nasion–point B angle, overjet, midfacial length, and mandibular length.
Conclusions: The PNSceph should not be regarded identical to the three-dimensionally assessed radiographic boundary of maxillary molar distalization. However, the regression equation found in this study provided an alternative to predict the amount of maxillary molar distalization in patients with Class III malocclusion and moderate crowding.
Ye, Jhong-An; Tsai, Chi-Yu; Lee, Yi-Hao; Chang, Yu-Jen; Lin, Shiu-Shiung; Lai, Jui-Pin; and Wu, Te-Ju
"Could Cephalometric Landmarks Serve as Boundaries of Maxillary Molar Distalization? A Comparison Between Two- and Three-Dimensional Assessments,"
Taiwanese Journal of Orthodontics: Vol. 33:
3, Article 1.
Available at: https://www.tjo.org.tw/tjo/vol33/iss3/1
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