The association between thread pitch and cortical bone thickness influences the primary stability of orthodontic miniscrew implants: a study in human cadaver palates

Abstract

Objective: The purpose of this study was to mathematically evaluate the influence of variations in thread pitch and cortical bone thickness on the maximum insertion torque (MIT) and implant stability (IS) of miniscrew implants (MIs).

Methods: Sixty custom made MIs with a 0.4-, 0.6-, 0.8-, 1.0-, or 1.2-mm thread pitch,12 for each pitch, were randomly placed into the palates of 10 embalmed human maxillae. The MIT was measured with a hand-operated digital torque reader screwdriver with a holding guide, and the IS test was performed using Anycheck. Conebeam computerized tomography was used to measure the cortical bone thickness(CBT) at each MI site. One-way ANOVA, Tukey post hoc test, Pearson's correlation,and multiple linear regression models were performed using the SPSS program.

Results: The MIT and IS tests demonstrated a pitch-dependent decrease. The pitch had a strong negative correlation with MIT and IS, while the CBT had a strong positive correlation with those outcomes. The association between pitch and CBT significantly influenced MI primary stability. Moreover, a strong correlation was found between MIT and IS.

Conclusions: The MI primary stability, MIT, and IS are strongly influenced by theassociation between MI thread pitch and CBT.

Keywords: Cortical bone thickness; Human study; Miniscrew implants; Primary stability; thread pitch.