Three-dimensional monitoring of root movement during orthodontic treatment.

INTRODUCTION: A significant objective of orthodontic treatment is to achieve proper and stable tooth positions that involve not only the crowns, but also their roots. However, the current methods of clinically monitoring root alignment are unreliable and inaccurate. Therefore, the purpose of this study was to develop a methodology that can accurately identify root position in a clinical situation. METHODS: Pretreatment and posttreatment cone-beam computed tomography (CBCT) and extraoral laser scans of study models of a patient were obtained. Threshold segmentation of the CBCT scans was performed, resulting in 3-dimensional surface models. The pretreatment CBCT teeth were isolated from their respective arches for individual tooth manipulation. These isolated pretreatment CBCT teeth were superimposed onto the posttreatment surface scan depicting the expected root position setup. To validate the accuracy of the expected root position setup, it was compared with the true root position represented by the posttreatment CBCT scan. Color displacement maps were generated to measure any differences between the expected and true root positions. RESULTS: Color map analysis through crown superimposition showed displacement differences of 0.148 ± 0.411 mm for the maxillary roots and 0.065 ± 0.364 mm for the mandibular roots. CONCLUSIONS: This methodology has been demonstrated to be an accurate and reliable approach to visualize the 3-dimensional positions of all teeth, including the roots, with no additional radiation applied.

Epidemiology, prognostic factors, and management of malignant odontogenic tumors: an analysis of 295 cases.

OBJECTIVE: To determine the demographic characteristics, prognostic factors, and management for patients diagnosed with a malignant odontogenic tumor (MOT). STUDY DESIGN: The Surveillance, Epidemiology, and End Results (SEER) registry was reviewed for patients diagnosed with MOT from 1973 to 2011. Kaplan-Meier and multivariate Cox regression analyses were performed on patient demographic characteristics and pathologic variables. RESULTS: The SEER database identified 295 MOT patients. The mean age at diagnosis was 50.5 years (range 5-89 years). Of these patients, 61.7% were male and 38.3% were female. The racial composition was 66.4% White, 22% Black, 6.1% Asian, 3.1% Pacific Islander, 0.3% Native American, and 2.1% Other/Unknown. Kaplan-Meier analysis found an overall survival (OS) and disease-specific survival (DSS) at 5 years of 54% and 67%, respectively. Multivariate analysis of the entire cohort found that age and stage were predictors of OS and that age was a predictor for DSS. For stage I/II MOTs, age and surgical therapy were predictors of OS and DSS, respectively. CONCLUSIONS: Here we report the largest study to date investigating demographic characteristics, prognostic factors, and management of MOT patients. Determinants of survival for OS and DSS include age, stage, and surgical therapy.