UBC Theses and Dissertations
Digital and clinical registration methods in assessing the fit of tooth-supported components in selective laser melted partial denture frameworks Alabdullah, Sarah Almoheeb
Objectives: Advances in three-dimensional (3D) printing technology have improved the fit of Partial Removable Dental Prostheses (PRDP) frameworks made by Selective Laser Melting (SLM). Conventionally, the gaps between master casts and these PRDPs have been evaluated using clinical replicas. More recently, digital evaluations have provided an alternative way to measure these gaps. The aim of this project was to assess the similarities and differences between digital and conventional methods used to evaluate the fit of SLM PRDP frameworks. Methods: A printed resin master cast, representing a Kennedy class II mod 2 design with 5 pyramidal markers, was made from a dentiform model. 12 SLM Co-Cr PRDP frameworks were fabricated on this master cast by means of a digital design software. Gaps between the frameworks and the cast were assessed using the clinical replica method by inserting a silicone impression material prior to their seating, then measuring the silicon thickness at each marker with a caliper. Digital models of each framework and the master cast were scanned and registered with CloudCompare software also employed to measure 3D gaps at the 5 reference markers and 3 occlusal rests. The results were analyzed by one-way ANOVA and post-hoc Bonferroni tests. Results: The mean gap between the frameworks and master cast for clinical registration was 13.96 ± 7 microns. The mean gap for digital registration was 70.76 ± 24 microns. Statistically significant differences among the pyramidal markers were found in both approaches. There were no statistically significant differences among the frameworks. In both cases gap measurements were well below a 300-micron limit considered clinically acceptable. Conclusion: Both registration methods can help determine whether the fit of an SLM framework is clinically acceptable. Differences in the values they provide are most likely due to unique factors affecting both methods of measurement.
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