Influence of the tooth position, guided sleeve height, supporting length, manufacturing methods, and resin E-modulus on the in vitro accuracy of surgical implant guides in a free-end situation.

Abstract

The study aims to evaluate the effect of tooth position, sleeve height, supporting length, resin E-modulus, and manufacturing method on the accuracy of dental implants placed in vitro fully guided in a lower jaw free-end situation. Using resin clones of a patient case providing a free-end situation 384 implants has been experimentally placed guided. The accuracy of postoperative implant position analyzed depending on the tooth position (first and second molar), sleeve height (2 and 6mm), supporting length (tooth no. 37-33 and 37 43), resin E-modulus (<2,000, >2,000, and >3,000MPa), and manufacturing method (milled, printed). To determine the three-dimensional accuracy angular deviation, mean crestal, apical deviation, and the linear vertical deviation at apex were calculated separately for each group (n=12). The accuracy of implant placement using milled guides was affected only by the tooth position, indicating stronger deviation of implants replacing second molars than first molars. Considering printed guides, the implant position was influenced by tooth position, sleeve height, and supporting length. Linear vertical deviation >1mm was found for printed materials with the lowest E-modulus at tooth position no. 37. Logistic regression analysis revealed a significant lower odds for linear vertical deviation >1mm for materials with higher E-modulus (OR: 0.04; 95% CI:0.01-0.97; p=.048) and higher ratio for smaller sleeve height (OR: 2.77; 95% CI:1.20-6.38; p=.017). Accuracy of implant placement in a free-end situation lacking distal tooth support is superior for milled as compared to 3D-printed surgical guides. When using 3D-printed surgical guides, smaller sleeve heights and extended tooth support improve the accuracy of implant placement.