Assessment of miniscrew implant stability by resonance frequency analysis: a study in human cadavers

Resonance frequency analysis (RFA) is a reliable, noninvasive method of measuring dental implant stability in vivo. However, the possibility of using this method to assess the stability of miniscrew implant has not been investigated. The purpose of this study was to evaluate the possibility of using RFA to assess the stability of miniscrew implants placed in different sites in the maxillae and mandibles of cadavers.

Ten pairs of dentate maxillas and mandibles were retrieved from human cadavers. Two hundred self-drilling miniscrew implants of 1.5-mm diameter and 8-mm length were systematically inserted into the dentoalveolar bones aided by a 3-dimensional surgical guide. Maximum insertion torque value was recorded during implantation procedures. Assessment of primary stability was carried out immediately after implantation using the RFA method, and implant stability quotient (ISQ) values were recorded. Analysis of variance, the Student t test, and generalized estimating equation regression analyses were used to analyze the data.

A strong correlation was found between maximum insertion torque and ISQ values (r = 0.873). Maximum insertion torque and ISQ values were significantly higher in the mandible (15.8 ± 3.3 N-cm and 71.7 ± 12.1) than in the maxilla (11.8 ± 3.8 N-cm and 56.0 ± 15.8). Miniscrews inserted in the posterior region of the maxilla exhibited the lowest ISQ values. No significant difference among ISQ values of miniscrews inserted in the anterior, middle, or posterior regions of the mandible was observed.

Estimates of implant stability using resonance frequency analysis are highly correlated with maximum insertion torque. Further studies to assess the primary stability of miniscrew implants in the clinical situation are necessary.