Histological and immunohistochemical evaluation of low-level laser therapy to prevent root resorption during orthodontic tooth movement

Abstract

The orthodontic tooth movement is a complex biological process that induces periodontal tissue reactions in response to biomechanical forces and leads to a remodeling process for subsequent alveolar bone resorption on the pressure side and bone apposition on the tension side. When heavy forces are applied, beside these changes in bone tissue, structural alterations may occur on the dental tissue due to loss of cementoblatic layer, which exposes teeth to osteoclasts, resulting in a pathological process of root resorption. Low-level laser therapy is capable of photobiomodulation, either through a bio-inhibiting or bio-stimulating process in a cellular and molecular level, depending on protocol. Thus, the purpose of this study is to evaluate the effects of low level laser therapy in reducing areas of root resorption during tooth movement in mice. The sample will consist in 45 rats on which it will be induced tooth movement for 14 days, using an appliance proposed by Heller and Nanda (1979) and modified by Martins-Ortiz (2004) and divided into groups with and without laser irradiation. The study will evaluate the acceleration of tooth movement through dental linear measurements on dental casts, semi-quantitative histomorphometric analysis and immunohistochemical analysis and through the presence and extent of root resorption in histological sections. (AU)