Newly defined landmarks for a three dimensionally based cephalometric analysis: A retrospective cone beam CT scan review.
Abstract: Introduction: A patient's anteroposterior (AP) skeletal relationship is an important aspect in orthodontic diagnosis and treatment planning. All two dimensional analyses for skeletal diagnosis are inherently flawed, but the advent of cone beam CT (CBCT) scans has provided the clinician with a new method of analyzing skeletal relationships in three dimensions. The purpose of this study ... read morewas two-fold: 1) Develop new landmarks and a three dimensionally based cephalometric analysis that can differentiate between class I, II and III patients. 2) Compare how well the new analysis can predict molar relationship compared to traditional two dimensional analyses (ANB, Wits and APDI). Methods: Full head CBCT scans of one hundred and five patients (57 class I's, 26 class II's and 22 class III's) with all first molars in occlusion and all primary second molars still present, were obtained from a private office. Invivodental (Anatomage) v5.1 was used to analyze the CBCT scans in the sagittal and axial planes to create new landmarks and a linear three dimensional analysis (µ measurement) based on anterior maxillary and mandibular centroids. One-way ANOVA was used to compare means between groups and volume under curve (VUC) analysis was used to compare how well each analysis could predict the patient's molar relationship. Results: The µ measurement, ANB and Wits could statistically differentiate between the means of class I and III (p < 0.001, p < 0.01 and p < 0.001, respectively), as well as class II and III patients (p < 0.001), but not between class I and II patients. The µ measurement was not a better predictor of molar relationship compared to any of the traditional two dimensional analyses. Conclusion: There is insufficient evidence to conclude that the µ measurement is a reliable three dimensional analysis for diagnosing the patient's skeletal pattern. Further research is needed to define additional landmarks and to develop a true three dimensionally based skeletal analysis.
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Orthodontics.
Advisor: Matthew Miner.
Committee: Vicky Cartsos, Unae Han, Lokesh Suri, and Matthew Finkelman.
Keyword: Dentistry.read less