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The effects of radiotherapy on the endogenous proteases of sound and restored dentin

Grant number: 15/20297-3
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): March 01, 2016
Effective date (End): January 31, 2019
Field of knowledge:Health Sciences - Dentistry - Dental Clinics
Principal researcher:Ana Cecília Corrêa Aranha
Grantee:Sandra Ribeiro de Barros da Cunha
Home Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated scholarship(s):17/01777-0 - The effects of ionizing radiation on the distribution of cysteine-cathepsins in restored and sound dentin, BE.EP.DR

Abstract

According to the World Health Organization, in 2012, about 14.1 million new cancer cases worldwide were recorded, and more than 32.6 million people already diagnosed and living with the disease for at least five years. Oral cancer can affect the lips, oral mucosa, hard and soft palate, gums, tongue and salivary glands. It is considered a worldwide public health problem, since it is closely correlated to the use of tobacco and alcohol occurring a synergistic association with habits of poor oral hygiene. This cancer had a worldwide estimate of about 300 000 new cases for the year 2012. Currently there are several types of treatment for different types and locations of cancer, but we can say that the most commonly used treatments are surgery, radiotherapy and chemotherapy, making the tripod of cancer treatment. Despite the advantage of preserving tissue structure, radiation therapy in head and neck generally results in oral complications that affect oral mucosa, bones, muscles, dental structures and salivary glands. When the oral cavity is exposed to higher doses of radiation, clinical consequences including hyposalivation, mucositis, loss of taste, trismus, osteoradionecrosis and caries related to radiation therapy should be considered as the most common side effects.Regarding the restorative material of choice in patients irradiated it is a consensus in the literature that the dentist's first option is the composite resin, since glass ionomers suffers an early erosion due to dry mouth and decreased pH in the oral cavity, while the composite resin presents a greater integrity and longevity of the restoration.More recently, Tjäderhane et al., 2013, and Mazzoni et al., 2013 showed that changes in pH caused by dentin conditioning acids, the acid monomer and resin monomers of the adhesive itself can modulate the activation and expression of MMPs and CTs, resulting the increased degradation of collagen fibers within the hybrid layer.With the evolution of cancer treatment and the current longevity of teeth in the oral cavity, it is essential that the dentist is aware of the radiation changes in the oral cavity and can act correctly in both - pre and post cancer treatment.This study aims to analyze the location and activity of endogenous proteases on, irradiated in vitro and in vivo and sound dentin restored with different adhesives and the influence of these endogenous proteases on the properties of restorative materials in three different times.This study will be divided into two distinct phases:Fase 1: assessment of the location and activity of MMP-2 and -9 and CT-B and K and nanohardness between, irradiated in vitro and in vivo and sound teeth. Fase 2: Assessment of the location and activity of MMP-2 and -9 and CT-B and K in adhesive restorations before and after radiotherapy in vitro (C70Gy) identify whether there is a relationship between the activity of MMPs and CTs and influence in nanohardness of adhesives, composite and hybrid layer in three different times (24hrs, 6 months and 12 months after the restorative procedure).