The Utility of Evaluating Primary Stability of Implants Using Accumulated Insertion Torque Values: a Preliminary Study.

Objectives: This preliminary in vitro study aimed to clarify the usefulness of the accumulated torque value as a new method for evaluating primary implant stability.

Material and methods: Implants of different sizes (42-10ST and 37-6ST) and simulated bone blocks of different densities (D1 to D4) were used. The implant osteotomy was prepared following the manufacturer's drilling protocol in simulated bone blocks, and the implants were inserted (n = 10). The implant insertion torque value was measured at 0.05 seconds intervals. The peak value was recorded as the peak torque value (PTV), and the sum of the torque values measured from the start to the end of the implant insertion was recorded as the accumulated torque value (ATV). After implantation, the implant stability quotient (ISQ) was measured. Correlations among ATV, PTV, and ISQ were analysed.

Results: The ATV increased with the density of the simulated bone block. A strong correlation was observed between the PTV value and ATV value (42-10ST [P < 0.05, r = 0.99], 37-6ST [P < 0.05, r = 0.99]). In addition, a correlation was observed between the ATV and ISQ ISQ (42-10ST [P < 0.05, r = 0.81], 37-6ST [P < 0.05, r = 0.83]). The PTV was higher in the 42-10ST group than in the 37-6ST group from D1 to D4.

Conclusions: The accumulated torque value varied according to the density of the simulated bone block, and a correlation was observed with the existing implant stability evaluation method. This suggests that this method may be useful as a novel approach for evaluating primary implant stability.