Trueness of artificial teeth for CAD-CAM complete dentures fabricated with additive manufacturing implementing different denture base-tooth offset values: An in vitro study

Statement of problem. Computer -aided design and computer -aided manufacturing (CAD -CAM) removable dentures have become popular. However, evaluations of the effect of denture base -tooth offset (DTO) values on the trueness of artificial teeth are lacking. Purpose. The purpose of this in vitro study was to digitally measure the trueness of the artificial teeth of CAD -CAM dentures fabricated with additive manufacturing using different DTO values and to determine the most accurate DTO value. Material and methods. Seven study groups were formulated based on different DTO values, and 6 maxillary complete dentures were assigned to each group (n=42). A design software program was used to export the monoblock denture as control, the artificial teeth, and 7 different designs of denture bases with DTO values of 0.00, 0.01, 0.03, 0.05, 0.10, 0.15, and 0.20 mm. Denture bases were printed in denture base resin (Denture base RP; formlabs), artificial teeth were printed in tooth -shade resin (Denture teeth A2; formlabs), and both were then assembled and polymerized together. The dentures were scanned (InEos X5; Dentsply Sirona), scan data were imported in a measuring software program (GOM Inspect; GOM GmbH), and registration using local best fit was performed to align data. Color -coded maps for the surface comparison of each denture with the control denture scan were generated. Fitting center points were constructed for each artificial tooth, which were compared with their corresponding points on the data of the control scan. Multiple pairwise comparisons were performed after 1 -way ANOVA to quantify and statistically evaluate the deviation values (alpha=.05). Results. The 0.10 -mm DTO group showed the lowest values when comparing artificial tooth deviations both individually and as types. On comparing the average deviations, statistically significant differences were identified among the 7 groups ( P<.001). A nonstatistically significant difference was identified when the 0.10- and 0.05 -mm DTO groups were compared. Lower deviation values were found in the premolars compared with the molars, in the incisors compared with the canines, and in posterior artificial teeth compared with anterior teeth. Conclusions. The 0.10 -mm DTO value showed the highest trueness for the artificial teeth compared with the other DTO values tested in this study. The 0.05 -mm DTO value is an alternative to the 0.10 -mm DTO value for CAD -CAM dentures constructed by additive manufacturing. Anterior teeth of a CAD -CAM denture showed higher deviation values compared with posterior teeth.