Effects of obesity on periodontal tissues subjected to biomechanical forces

Abstract

Over the past decades obesity has been increasing worldwide and represents a major risk factor for many chronic diseases. Meta-analyses have demonstrated that obesity is also associated with periodontitis, a bacteria-induced inflammatory disease of the tooth-supporting tissues. Obesity is characterized by excess adipose tissue, which secrets bioactive molecules called adipokines. Although the effects of obesity on periodontitis and its therapy are a hot topic of current dental research, it has been largely neglected if obesity also affects the response of periodontal tissues to biomechanical loading, such as orthodontic tooth movement or occlusal forces. Although orthodontic tooth movement and mastication ideally occur in periodontal health, bacterial infection of the biomechanically loaded tissues can occur due to insufficient plaque control. Therefore, the main objective of the proposed in-vivo and in-vitro projects is to study the effects of obesity and adipokines on the actions of biomechanical forces on periodontal cells and tissues in the presence and absence of bacterial infection. Specifically, in an in-vivo study, orthodontic tooth movement in the presence and absence of ligature-induced periodontitis will be performed in Holtzman rats fed either with high-fat or standard diet. Afterwards, periodontal tissue remodeling will be analyzed morphologically by microcomputed tomography and histomorphometry, and protein synthesis of molecules related to inflammation, tissue metabolism and intracellular signaling will be investigated by proteomic analysis. Additionally, in an in-vitro study, periodontal cells will be subjected to biomechanical strain and/or the periodontopathogen Porphyromonas gingivalis in the presence and absence of adipokines. Subsequently, molecules related to inflammation, tissue metabolism, and intracellular signaling will be analyzed, thereby expanding the in-vivo findings with a special focus on adipokines as a possible local obesity-associated pathomechanism. Together, the in-vivo and in-vitro projects will provide novel and critical information on the effects of obesity and adipokines on periodontium subjected to biomechanical forces. By clarifying the role of obesity on periodontal tissues subjected to biomechanical loading and unraveling pathophysiological events, molecules and signaling pathways involved, the proposed pre-clinical project will serve as a basis for a clinical follow-up study, which may open up new orthodontic treatment protocols in overweight and obese individuals. (AU)