Does the fixture thread depth affect the accuracy of implant placement during fully guided immediate implant placement?: A human cadaver study

Background The fixture thread depth reportedly influences the primary stability of dental implant, but its effect on the positional accuracy in immediate implant placement has not been reported previously. Materials and Methods Fifty‐six single‐rooted, anterior and premolar teeth were extracted from six human cadavers, followed by installing either regular‐threaded implants (RT group, N = 30) or deep‐threaded implants (DT group, N = 26) completely relying on the surgical guide. Optical impressions taken after osteotomy and fixture installation were superimposed with the preoperative virtual planning data to measure the vertical, angular, platform and apex deviations that occurred during osteotomy and installation. Results While the osteotomy deviations were similar between the two groups, the angular and apex deviation of the DT group (2.67 ± 2.56°; 1.04 ± 0.49 mm, respectively) were significantly larger than those of the RT group (1.61 ± 1.04°; 0.67 ± 0.41 mm, respectively) during installation (p