EFFECT OF LOW LEVEL LASER THERAPY AND EPIDERMAL GROWTH FACTOR ON IN VITRO BIOLOGICAL SEALING INDUCTION

Abstract

The attachment of connective tissue to the surface of abutments of dental implants prevents the apical migration of the junctional epithelium and the consequent bone crest reabsorption. When bacterial contamination and peri-implant inflammation take place, cells lose their potential to adhere to the substrate, resulting in apical migration of the epithelium what compromises this aesthetic treatment. The use of therapies to accelerate or enhance cell adhesion, inducing an effective biological sealing may improve the aesthetic and functional conditions in prosthetic rehabilitation. Therefore, the aim of this study is to assess the effects of low level laser therapy (LLLT) and the impregnation of titanium (Ti) and zirconia (ZrO2) surfaces with epidermal growth factor (EGF) on adhesion and metabolism of human oral mucosa cells exposed or not to lipopolysaccharide (LPS) of Porphyromonas gingivalis (P. gingivalis) or tumor necrosis factor ± (TNF-±). For this purpose, gingival fibroblasts and epithelial cells will be seeded on Ti and ZrO2 discs, simulating an in vitro biological sealing. In groups with EGF, the growth factor will be applied to the surfaces of both materials before cell seeding. Then, the cells will be irradiated for 3 times at 24-h intervals using doses of 0.5 J/cm2; 1.5 J/cm2 and 3.0 J/cm2 according to the established groups and TNF-± or P. gingivalis LPS will be applied for 24 h. Cell viability (MTT assay), collagen quantification (Sirius Red), gene expression of VEGF, IL-6, IL-8 and TNF-± (qPCR), synthesis of VEGF, IL-6, IL-8 and TNF-± (ELISA) as well as expression of e-cadherin and phalloidin (immunofluorescence) and cell morphology analysis (MEV) will be assessed. Specific statistical testes will be selected and then used to analyze the obtained data at 5% significance level.