Effect of chitosan experimental solution with natural extracts on physical, morphological and adhesive properties of root dentin

Author(s)

Tatiana Carvalho Montes

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2018-06-12

Examining board members

Simone Cecilio Hallak Regalo; Cesar Penazzo Lepri; Marcelo Oliveira Mazzetto; Paulo Vinicius Soares

• Advisor: Regina Guenka Palma Dibb

Abstract

The aim of this study was to analyze the changes in root dentin permeability and morphology when treated with a chitosan experimental solution containing green tea (EGCG) and gardenia fruit (genipin) naturals extracts, through the dentin hydraulic conductance measurement and morphology and to evaluate its effect on bond strength in composite resin restorations, through the microtensile test. Specimens were made from the root dentin of bovine incisors. For the dentin permeability test and laser confocal microscopy analysis, 45 dentin disks with 4mm diameter and 1mm thickness were used, divided into 3 groups (n = 15): control (C), Dessensibilize Nano P (NP ) and chitosan experimental solution (ES). Three measurements of dentin permeability were performed: Minimum permeability (smear layer presence on the dentin discs outer face); maximum permeability (removal of smear layer with 6% citric acid) and post-cycling permeability/treatments (citric acid 0.3% erosive cycling and desensitizing treatments), with laser confocal microscopy after the erosive challenge (maximum permeability) and at the end of the cycling/treatments. Thereafter, 30 specimens of 6 x 6mm were divided into groups (n = 10) according to the desensitizing treatment (control - without treatment; Desensibilize Nano P; chitosan experimental solution) for microtensile test. The desensitizing agents were applied to the surface of the demineralized dentin after exposure to hydrochloric acid (pH 1.2), thereafter a 4mm plateau of composite resin was made. The restored specimens were cut into 1x1 mm fragments and taken to the universal test machine for testing at a 0.5 mm / min speed with a 500 N load cell. The fracture patterns were analyzed in a confocal laser microscope. Mann-Whitney test (α = 5%) was used for comparisons of maximum and minimum permeability to post-cycling / treatments within each group and between groups. For microtraction, in means comparison between groups, ANOVA 1 criteria with Tukey test (α = 5%) was used. The data obtained from the difference between the final and the initial for dentin tubules number, area and perimeter were submitted to the Kruskal-Wallis test (α = 5%). The NP and ES groups showed a significant decrease in dentin permeability for all analyzes, but in the control group there was an increase in the hydraulic conductance. ES did not influence in dentin bond strength of composite resins, however, NP25 reduced it significantly. The largest number of dentinal tubules obliterations was verified in ES group. It can be concluded that ES decrease dentin permeability, closed dentin tubules without negatively affected the adhesion. (AU)

• FAPESP's process: 16/12786-7 - Efficacy of experimental chitosan solution with natural extracts in permeability and dentinal tubule occlusion
• Grantee: Tatiana Carvalho Montes
• Support Opportunities: Scholarships in Brazil - Master