The effect of a surgeon’s position on the axial inclination 
of dental implants placed freehand: a single-blind study

Objectives: To examine whether a surgeons’ position affects the axial angulation of dental implants placed freehand.
Method and materials: Implants’ axial angulation was assessed on digital panoramic radiographs. An occlusal line was plotted based on the neighboring teeth/crowns. The mesial angle between the long axis of the implant and the occlusal line was measured. In addition, post-hoc ideal implant-positioning planning was done on the panoramic digital image, and the angle of the intersection between the long axis of the actual and post-hoc ideal implant was measured. Student t test for unpaired observations and the Kolmogorov-Smirnov nonparametric tests were utilized to compare the ipsi- and contralateral sides and between clinicians.
Results: Seventy-seven patients (149 implants) were eligible for the study. Implants had slight mesial inclination (mean 97.7 ± 8.7 degrees) which was similar for both the ipsi- (98.2 ± 8.4 degrees) and contralateral sides (97.2 ± 9.1 degrees), P = .491. For the post-hoc planning versus actual placement comparison, the overall median (interquartile range) of implant angular deviation was minimal (−0.25 degrees [−2.98, +3.47]). This was true for both the ipsilateral (−0.5 degrees [−2.9, +2.9]) and contralateral (−0.2 [−4.2, +5.4]) sides, P = .55. For the actual versus post-hoc planning, most observations clustered around the midline (zero to minimal deviation), while for the implant to occlusal plane angle, a tendency towards slight mesial angulation was observed.
Conclusions: Dental implants placed freehand by experienced clinicians have only slight axial deviation as measured from post-hoc optimal position. Implants placed in ipsilateral and contralateral sides and by left- and right-dominant-hand clinicians had similar angulations.