Dentin-resin bond evaluation using different dentin conditioning approaches

Author(s)

Maicon Sebold

• Document type: Master's Dissertation
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2017-02-21

Examining board members

Marcelo Giannini; Ivarne Luis Santos Tersariol; Valentim Adelino Ricardo Barão

• Advisor: Marcelo Giannini

Abstract

This study evaluated the effects of different dentin conditioners (37% phosphoric acid; 10-3 solution; ferric oxalate, and nitric acid) on the microtensile bond strength of two adhesive systems, flexural strength and elastic modulus of dentin and the morphology of the resin-dentin interface. Two bonding systems were tested: XP Bond (Dentsply) and One-Step (Bisco). The adhesives were applied on wet (positive control group) and dry (negative control group) dentin after phosphoric acid-etching. The experimental groups consisted in the application of adhesives on dry surfaces after dentin conditioning with 10-3 solution, 6.8% ferric oxalate or 1.4% nitric acid. Eighty human third molars were divided into 10 experimental groups for the bond strength test (n=8). The flexural strength and elastic modulus test required the use of 25 bovine incisors, which were reduced to dentin bars with dimensions of 0.5 mm x 1.7 mm x 7 mm. Adhesive interface analysis was performed under laser scanning confocal microscopy by preparing 30 teeth for the same groups from the bond strength test (n=3). Bond strength data were analyzed by two-way ANOVA (dentin treatment and type of adhesive), whereas results from the flexural strength test were analyzed by one-way ANOVA (dentin treatment). Both strength assays were subjected to the Tukey test. The structures observed in the microscopic evaluation were described and compared amongst groups. Application of XP Bond after dentin treatment with 10-3 solution showed lower bond strength than the positive control group and no statistical difference was detected compared to the negative control group within the same adhesive. Ten-three solution associated with One-Step resulted in bond strength statistically similar to the positive control group and higher than the negative control group of the same bonding system. Nitric acid-conditioning followed by the application of XP Bond produced lower bond strength in comparison to both control groups of XP Bond. Bond strength values found for the association between nitric acid and One-Step were higher than the negative control group and statistically similar to the positive control group of One-Step. Hybrid layer and resin tags formation occurred in all teeth treated with 10-3 solution or nitric acid. Ferric oxalate was not capable to promote hybridization and resulted in the lowest bond strength for XP Bond. Bond strength obtained by the use of One-Step on ferric oxalate-treated dentin presented no statistical differences compared to the negative control group. Dentin elastic modulus was not affected by any of the conditioning agents used. A reduction in dentin flexural strength was observed only for the ferric oxalate group. In conclusion: for the adhesive One-Step, resin-dentin bonds similar to the group where the bonding agent was applied on wet, phosphoric acid-etched dentin can be achieved by the use of 10-3 solution or nitric acid; the conditioning agents tested were not able to affect dentin stiffness; flexural strength was jeopardized by surface treatment with ferric oxalate (AU)

• FAPESP's process: 15/03927-3 - Evaluation of the resin-dentin bond using different approaches in dentin conditioning
• Grantee: Maicon Sebold
• Support Opportunities: Scholarships in Brazil - Master