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UBC Theses and Dissertations

Novel methods to assess three-dimensional tooth movement for the maxillary and mandibular dentitions Alwafi, Abdulraheem Abdullah


Background Dental movement and position analyses are crucial for both clinical and research reasons. Previous studies have used X-rays, including cephalometric radiographs, CBCT, or the digital model superimposition, to assess dental movements and positions. In this dissertation, we develop novel three-dimensional (3D) methodologies using relatively stable landmarks for maxillary and mandibular dentition superimposition, dental movement measurements, and their applications in assessing the efficacy of clear aligner treatment. Methods This dissertation consists of a literature review (chapter 1), maxillary dentition (chapter 2), and mandibular dentition (chapter 3) methodologies for superimposition and dental tooth movement measurement and their application in assessing the efficacy of Invisalign treatment. Additionally, the construction of the long axes of different tooth parts in the anterior segment was demonstrated, compared, and discussed (chapter 4). Finally, chapter 5 includes a discussion, summary, overall strengths and limitations, clinical implications, future directions, and the study’s conclusion Results Our research projects developed novel methodologies to assess tooth movement in maxillary and mandibular dentitions, with high intra- and inter-examiner correlation coefficients (ICCs) agreement. Anteroposterior (AP) and buccolingual translational movements of all posterior teeth appeared to be accurate, with insignificant differences between ClinCheck® predicted and post-treatment digital models (P=1.000). Rotation and torque movements were less accurate with statistical significance (P=0.0012 and 0.00029, respectively). For the mandibular dentition, premolar rotation, incisor tipping, and molar AP movement showed a significant prediction difference at the 5% level. In terms of the long axis measurement, the long axis of the “Crown” appeared to be the furthest from the tooth composite long axis for the “Canine” when compared to the other anterior teeth (P= <0.0001). Conclusion The method developed for maxillary dentition tooth measurement is robust, reliable, user-friendly, and no radiation is involved. Achieving the predicted vertical, rotation, and torque tooth movements seems more challenging for specific maxillary posterior teeth during treatment with Invisalign. The method involving CBCT and dental superimposition to measure the 3D positional changes in the mandibular dentition is robust, reliable, and novel. Finally, determining the actual long axis of a tooth is challenging due to varying tooth morphology, differing imaging quality, and operator segmentation errors.

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