The Study On Design And Accuracy Of CAD/CAM Surgical Guide

Objectives:Combined with the technologies including computed tomography, optical scanning, image processing, reverse engineering and rapid prototyping manufacturing, the study has researched the fabrication and accuracy of the CAD/CAM surgical guide.Methods:1. CT date was imported to Mimics software to be reconstructed. Optical scan data and CT data were registered in Geomagic software. The surgical guides were designed in Geomagic software after the registration and were fabricated using rapid prototyping manufacturing. Implant alternatives were used representing the implant position and were recorded using an optical scanner. Deviations were calculated in Geomagic software. Data was assessed using one‐way ANOVA (α=0.05).2. The metal guide was a block with twelve holes fabricated using a5‐axes CNC milling workstation. Twelve holes were divided into four groups (2.2mm in Group A,2.8mm in Group B,3.5mm in Group C and4.2mm in Group D) according to the diameters of Straumann drills (Straumann Institue, Waldenburg, Switzerland). In each group, three holes were milled with varying tolerance between the drill and the sleeve (0.04,0.10,0.16mm). Drilling was executed in the model composed of resin box and metal guide. Angular discrepancy was investigated using an optical scanner and calculated in Geomagic software. Data was assessed using two‐way ANOVA (α=0.05).Results:1. The results of the angular discrepancy and longitudinal discrepancy at the entry point and the apex point of CAD/CAM surgical guides were2.551±1.336°,0.677±0.261mm and1.152±0.349mm (mean±SD) separately.2. Two‐way ANOVA demonstrated that tolerance between drill guide and drill did not significantly affect the angular discrepancy in each group (P＞0.05).Conclusions:1. The fabrication of the CAD/CAM surgical guides combined with computed tomography, optical scanning, image processing, reverse engineering and rapid prototyping manufacturing was feasible. The accuracy of the CAD/CAM surgical guides was similar to those of commercial implant systems, which was suitable for clinical application.2. Precision and stable surgical guides with tolerance of0.16mm between drill guide and drill allowed placement as accurate as guides with tolerance of0.04and0.10mm.