Purpose: The purpose of this in vitro study was to assess the accuracy of two surgical guides of differing size, as well as evaluate possible deformation of surgical guides following sterilization.

Material and methods: Sixty maxillary 3D-printed models were fabricated with the first premolar missing. Sixty surgical guides were preoperatively designed (3Shape Implant Studio) and fabricated using a digital light-processing printer (Vida, Envisiontec). Thirty guides were designed with the support of four teeth and thirty guides with the support of six teeth. Sixty dental implants were inserted using fully guided surgery, digital scan of dental implants was performed (Atos Core 135, GOM). The surgical guides were sterilized using steam heat. Corresponding datasets of the planned and final dental implant position as well as datasets of pre- and post-sterilization were analyzed (GOM Inspect 2017, GOM Metrology). For implant position, deviation at entry point; deviation at apex; vertical deviation; horizontal deviation (mm) and angular deviation (degrees) was measured. For post-sterilization evaluation, central sleeve position (mm) and angular deviation (degrees) was measured.

Results: No statistically significant differences in implant position deviation were found between the groups (p < 0.05). A statistically significant difference was found in angular deviation between the groups (p = 0.031).

Conclusion: The results in this study indicate a similar accuracy of a surgical guide with two mesial respectively distal tooth supports in comparison to a guide with three mesial and three distal tooth supports. Larger guides appear to be more affected by heat sterilization with regard to angular deviation.