Evaluation of anti-proteolytic potential by in situ zymography of bioactive dentifrices on sound and post-radiotherapy dentin

• Grant number: 23/09002-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2023
• End date: November 30, 2024
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Linda Wang
• Grantee: Hugo Bertoni Braga
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The diversity of possibilities of alteration of dentin substrate determines preventive and interventional actions according to the involved condition. Based on Person-Centered Care (PCC), shared actions with patients make the results more effective and long lasting. In this purpose, dentifrices are inexpensive and well-accepted vehicles. In the last years, the use for diverse actions transcended their prescription. Patients submitted to head and neck radiotherapy are susceptible to fast-evolution radiation caries lesions, even after preventive dental treatment. Besides the concept of high-fluoride content dentifrices, the current market launched interesting options with bioactive ingredients with distinct mechanisms of action aimed to reinforce the dentin structure and preserve more than heal. This in vitro, parallel and blindedstudy aims to analyze the anti-proteolytic potential by in situ zymography and mineralization degree by surface microhardness of dentin treated with bioactive dentifrices on sound and submitted dentin to radiotherapy. Sixty sound human third molars will be carefully selected and half will be subjected to radiotherapy protocol.Following, they will be randomized into groups according to the dentifrice: Biomin F (bioglass)-B, 5% S-PRG paste (xerogel)- SPRG, Elmex Erosion (chitosan and tin)-E, Clinpro 5000 (high F, fTCP)-CP, Colgate Total 12 (control)-CT and no brushing control)-C, which will be prepared as slurries (1:3 with deionized water) and activelyapplied for 30s. For the in situ zymography (n=5), 0.1mm slices will be prepared after the dentifrice application during cycling to be incubated with gelatin conjugated withfluorescein for 48h on 37 oC. Specimens will be assessed by Laser Confocal and Eletronic Scanning Microscopy to surface and longitudinal characterization and the gelatinolytic activity will be quantified by means of in situ zymography. For surfacemicrohardness (n=5), Knoop indentation will be performed (KHN, 10KgF, 10s) before and after dentifrice treatment. Surface characterization will be made by confocal and electron scanning microscopies (n=3), besides Energy Dispersive Spectroscopy. Datawill be quantified and, in the case of normal distribution, they will be analyzed by 2-way ANOVA and post-hoc Tukey tests (p<0.05); in the absence of normal distribution, they will be logarithmized to allow the parametric factorial analysis described above.