[Light forces and orthodontic displacement: a critical review].

Light or optimal forces are currently the focus of many clinical studies. In the literature, a positive correlation between light forces and speed of displacement is often acknowledged. Now, the consensus is neither total nor scientific and the existence of an optimum force level is still the center of discussion, as witnessed by numerous publications. With the new scientific analysis techniques and the advances made in biological and genetic research, we need to rethink these viewpoints from both the biological and mechanical standpoints since cellular and molecular transformations account for the series of events leading up to damage-free orthodontic displacement. The aim of this paper is to report on recent data regarding the bio-adaptability of teeth and periodontium to orthodontic forces systems in order to enhance our understanding of the physiology and physiopathology involved. Such understanding is a must if we are to optimize our treatment arsenal and achieve greater control of treatment times which are frequently judged excessive. Copyright 2009 Collège Européen d'Orthodontie. Published by Elsevier Masson SAS.. All rights reserved.