Influence of Augmented Reality Appliances on Tooth Preparation Designs-An In Vitro Study.

The aim of this work was to analyze and compare the tooth structure removal between a free-hand preparation technique and a computer-aided preparation technique using an augmented reality appliance for complete-crowns preparation designs and "root mean square" (RMS) alignment value. Ten upper teeth representatives of all dental sectors were selected from a generic model library as "Standard Tessellation Language" (STL-1) digital files and 3D-printed in an anatomically based acrylic resin experimental model. Then these were randomly assigned to the following tooth preparation techniques: Group A: free-hand preparation technique ( n = 5) (FHT) and Group B: computer-aided preparation technique using an augmented reality appliance ( n = 5) (AR). Experimental models were submitted to a digital impression through an intraoral scan and (STL-2) uploaded into a reverse engineering morphometric software to measure the volumetric reduction in the planned and performed tooth structure (mm 3 ) and RMS using the Student's t -test and the Mann-Whitney non-parametric test. Statistically significant differences were observed between the volumetric reduction in the planned and performed tooth structure (mm 3 ) of the AR and FHT study groups ( p = 0.0001). Moreover, statistically significant differences were observed between the RMS of the planned and performed tooth preparations in both the AR and FHT study groups ( p = 0.0005). The augmented reality appliance provides a more conservative and predictable complete-crowns preparation design than the free-hand preparation technique.