Abstract
OBJECTIVES: this in vivo study reports on mechanical torque data as well as the biological evaluation up to 6 weeks after placement of implants with a unique wide knife thread design in a goat iliac crest model. We hypothesized that implants with this thread design would show substantial primary stability at a continuous level toward secondary stability. METHODS: 64 MegaGen Anyridge® implants were used with diameters 3.5 mm, 4.0 mm, 5.0 mm and 6.0 mm (n = 8). Implants were placed monocortically in the iliac crest of 16 healthy female Saanen goats, both on the right (for torque measurements) and left side (for histology/-morphometry). Torque-in at implant installation and torque-out at 2 and 6 weeks of implantation was measured, as well as bone-to-implant contact (BIC) and bone-area between the screw threads (BA). RESULTS: Histology showed intimate bone-to-implant contact with a maturating trabecular structure between 2 and 6 weeks. Torque values showed a dependency on implant diameter. For all implant diameters, torque-in values were similar to torque-out values at 2 weeks. At 6 weeks however, all torque-out values were significantly increased. BIC and BA percentages showed similar values for all diameters at both 2 and 6 weeks. CONCLUSIONS: These results prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants in the goat iliac crest model. The increased torque-out values at 6 weeks without increasing BIC and BA percentages correlate with the observed maturation of bone-to-implant contact quality over time. CLINICAL SIGNIFICANCE: It is a challenge to optimize implants with continuous primary stability and rapid transition into secondary stability to minimize the duration of the lag-phase. The results of this study prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants. Consequently, the data from this work are important for the treatment of individual patients 'translating' these findings into clinical implant procedures.
