Does cortical thickness influence the primary stability of miniscrews? A systematic review and meta-analysis

Objective: To investigate whether there is evidence to support the association between cortical thickness (CtTh) and the primary stability of mini-implants (MI). Materials and Methods: A search was performed including articles published until September 2013. The inclusion criteria comprised observational clinical studies conducted in patients who received monocortical MI for orthodontic anchorage and in vivo or ex vivo experimental studies performed to evaluate the primary stability of MI, studies that evaluated the association between CtTh and MI primary stability, CtTh measurement performed numerically, and MI primary stability evaluated by implant stability quotient value, Periotest value, pull-out strength, or insertion torque. Studies conducted exclusively in artificial bone or finite elements were excluded. Results: Abstract and title reading identified 15 possible articles to be included. After reading the complete text, three were excluded. One article was found by hand searching and another excluded for an overlapping sample. Finally, 12 articles were selected. A positive correlation was found between primary stability and CtTh when studies that evaluated primary stability through PS were grouped (r =.409) and when studies that evaluated stability in humans were grouped (r =.338). Conclusions: There is a positive association between MI primary stability and CtTh of the receptor site. However, there is still a lack of well-designed clinical trials.