The aim of this study was to determine the influence of different frontal bone defect localizations on primary stability values of 2 different implant designs. Eight cow rib segments were prepared before implant installation, as 2 segments with coronal, 2 with middle, and 2 with apical defects and 2 with control. Thirty-two cylindrical and 32 tapered implants were placed in the remaining 4 segments. Implant stability measurements were performed using electronic percussive testing and resonance frequency analysis. No significance was detected between the stability values of the 2 implant designs except the implant stability quotient (ISQ) of control groups. The tapered implants control group showed significantly higher lateral ISQs compared with cylindrical implants (P = 0.033). For both implant types, stability values were significantly lower in coronal defects (P < 0.01). No significant differences were detected in other defect types. Within the limitations of this study, it may be concluded that coronal defects may influence primary stability negatively, compared with middle and apical defects. Although statistically not significant, coronal defects caused lower primary stability values with the tapered design compared with parallel design.