Clinical Assessment of Primary Implant Stability Parameters Using a Stereolithographic Surgical Guide

Purpose: The objective of this investigation was to determine if there was a correlation between the circumferential mean bone density calculated quantified using computed tomography (CT), maximum applied insertion torque value, and the implant stability quotient (ISQ). Materials and Methods: Medical grade CT was utilized in conjunction with rapid prototyping to fabricate a stereolithographic (SLA) surgical guide. Nineteen self-tapping dental implants (OsseospeedTX ™) with a length ≥ 11mm were placed in eight patients using a SLA surgical guide, either tooth-mucosa supported or bone-supported. The circumferential mean bone density was quantified pre-operatively using CT in Hounsfield (HU) units using Facilitate™ computer-guided implant software. The maximum applied insertion torque value was recorded using the W&H ImplantMed™. Primary stability was quantified in ISQ values with the wireless Ostell™Mentor instrument using resonance frequency analysis (RFA) at the time of dental implant placement. Three measurements were taken from the buccal and lingual for a total of six measurements for each dental implant using RFA. The Pearson correlation coefficient was implemented to determine the presence of positive correlations between the parameters of circumferential mean bone density calculated using CT; the mean bone densities calculated using CT at the coronal, midcrestal, apical regions; maximum applied insertion torque value, and the implant stability quotient (ISQ). The linear regressions for the Pearson correlation coefficient were converted to p-values using biostatistics software (Systat™ software 13;Systat Software, Inc., Chicago, IL). A positive correlation amongst the parameters was reported when p-value < 0.05. Results: There was a positive correlation found between the circumferential mean bone density and the maximum applied insertion torque values for all implants (r = 0.862, p < 0.001). No correlation was found between circumferential mean bone densities and the mean ISQ values (r = 0.275, p > 0.05). No correlation was found between the measurements of mean ISQ values and the maximum applied insertion torque values (r = 0.056, p > 0.05). Conclusion: A mean maximum applied insertion torque value of 33.2 Ncm for all dental implants was correlated with the circumferential mean bone densities calculated using CT pre-operatively. Since no correlation was found between circumferential mean bone density and the mean ISQ vales or between maximum applied insertion torque and the ISQ. It seems rationale to conclude that the high mean ISQ value of 72 ± 2.80 for all dental implants was a result of the surgical approach implemented using computer-guided implant software to maximize the length of a potential implant site to ≥ 11mm.