Efeito da aplicação de plasma atmosférico não térmico na superfície dentinária e na adesão do material restaurador

Author(s)

Ana Paula Almeida Ayres

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2017-02-17

Examining board members

Marcelo Giannini; Nelson Renato França Alves da Silva; Andre Figueiredo Reis; Américo Bortolazzo Correr; Rafael Pino Vitti

• Advisor: Marcelo Giannini

Abstract

This study aimed to evaluate the influence of non-thermal atmospheric plasma application onto the dentin surface, in the dentin-resin interface and in the bond strength of a universal adhesive system, Scotchbond Universal (3M ESPE). Two times of plasma application were analyzed: 10 and 30 seconds, in etch-and-rinse and self-etch adhesive techniques. In Chapter 1, the morphology and composition of plasma-treated surfaces were determined by Atomic Force Microscopy (n = 3) and Raman Confocal Spectroscopy (n = 5), respectively. Plasma influence in enzymatic activity of metalloproteinases was assessed by in situ Zimography. Microtensile test was used to determine the bond strength (n = 8) after specimen storage for 24 hours, one year and two years. Two aging methods were utilized: "direct water exposure" and "simulated pulpal pressure", which produced differences in bonding effectiveness and in failure pattern distribution. One-year stored specimens in "beam" shape showed prevalence of cohesive within resin failure and the bond strength decreased only for 30 s plasma-treated groups. Although these values did not statistically differ from the other groups after one year. When the samples were stored as restored teeth, with pulp chamber submitted to water column pressure, there was no difference among immediate and one-year bond strength, indicating bonding durability. Control groups showed statistically lower mean values, in etch-and-rinse and self-etch approaches, with predominant adhesive failure. The results from Chapter 1 indicate that plasma application on intact and demineralized dentin did not produce morphologic modifications related to surface roughness, neither alterations in `carbonate¿ and `type I collagen¿ spectrums. Only the `phosphate¿ spectrum decreased after plasma application for 10 s. In etch-and-rinse technique, zimography images of untreated dentin showed greater green fluorescence, which indicates high enzymatic activity, mainly in the hybrid layer. In Chapter 2, the same groups were restored and the samples stored for two years showed a decreased microtensile bond strength (n = 8), in self-etch technique. However, the groups that were plasma-treated kept the immediate bond strength values. Plasma treatment also increased the dentin hydrophilicity and produced higher nanohardness and Young¿s modulus means of the hybrid layer, when compared to control groups. In conclusion, the application of non-thermal atmospheric plasma onto dentin produced better results in the time of 30 s, without significant physical-chemical alterations of dentinal surface, increasing dentin hydrophilicity considerably. Regarding tooth-restoration interface, the treatment produced higher nanohardness (n = 3) and Young¿s modulus (n = 3) means in the hybrid layer, without apparently increase the enzymatic activity in this area. These effects seem to contribute to bonding longevity (AU)

• FAPESP's process: 13/15952-7 - Effect of argon plasma on the dentinal surface and the adhesion of restorative material
• Grantee: Ana Paula Almeida Ayres
• Support Opportunities: Scholarships in Brazil - Doctorate