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UBC Theses and Dissertations

Comparison of occlusal contacts on mounted dental models to contacts identified on digital 3D models using a new virtual alignment method Straga, Robert William


As 3D imaging of dental models becomes more common in clinical dentistry, the need for accurate images will increase. In order for these 3D models to be of greatest benefit, they will need to be aligned to accurately represent the given presentation of the individuals they represent. This is an important step, since the acquisition of digital models results in two unrelated image files. This study evaluated a new technique for aligning 3D digital dental models using a 3D scan of the anterior teeth in occlusion of articulator mounted models as a “virtual bite registration.” Three-dimensional digital models of one set of epoxy dental models were created using a commercially available 3D laser scanner (Konica Minolta Vivid 910) and Geomagic software. Ten mountings of these same epoxy models were made, and a 3D scan of the anterior teeth in occlusion was made for each mounting. The 3D digital models were registered to the anterior 3D scan, and virtual occlusal contacts were recorded and compared to the actual occlusal contacts recorded on the epoxy models using shimstock and articulating film. Comparison of the new technique to the standards was made using sensitivity, specificity, positive predictive value and negative predictive value analyses. Specificity was high when using both shimstock and articulating film contacts as standards and digital contacts as tests, 0.97 and 0.98 respectively. When comparing the traditional methods of recording contacts to the new digital technique the sensitivity with shimstock as the standard was 0.63 and with articulating film as the standard the sensitivity was 0.54. Positive predictive value and negative predictive value of the digital technique compared to shimstock was 0.52 and 0.98 respectively. Compared to articulating paper the values were 0.76 and 0.96 respectively. Using a scan of the anterior teeth in occlusion as a virtual bite registration represents an appropriate method for aligning 3D digital dental models in an anatomically correct position. The technique described may represent a good technique for future comparison of the alignment of digital models to the alignment found on articulator mounted models or in the patient regardless of hardware and software being used.

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