Dental bleaching with violet light: Effects on color change, bonding strength, hybrid layer nanohardness and collagen strength

Author(s)

Ana Carolina Souza Barboza

• Document type: Master's Dissertation
• Press: Araçatuba. 2019-10-22.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araçatuba
• Defense date: 2019-09-02
• Advisor: André Luiz Fraga Briso; Paulo Henrique dos Santos

Abstract

The aimof this project was to investigate the chromatic alteration, bond strength of dentin resin restorations, as well as to analyze the nanohardnessof the hybrid layer and the cohesive strength of dentin collagen, after performing different bleaching techniques. For this, 75 bovine teeth were randomly distributed: Control group; LED Group and GEL Group. Then, 45 teeth (n = 15) were destined to the analysis of the color change, being subsequently prepared, restored and sectioned on sticks. Half of the samples were submitted to the bond strength and mechanical properties tests of the hybrid layer, the remaining 10000 thermal cycles before the evaluations. The remaining 30 teeth were used to analyze collagen cohesive resistance (n = 10), which was performed immediately after bleaching treatments, as well as after collagenase action. The data obtained on color, bond strength, mechanical properties and collagen cohesive resistance were analyzed for normality using the Shapiro-Wilk test and submitted to the two-way ANOVA test with repeated measures and Tukey test (α = 0.05). . There was chromatic alteration in LED and GEL Group, with larger alterations of ∆E, ∆L and ∆b in GEL. In the adhesion test only thermocycling interfered in the results, presenting lower values in all groups. Nanohardness and modulus of elasticity values remained unchanged after the treatments (p> 0.05), while in the collagen cohesive resistance test, in the immediate analysis the GEL Group presented a control difference, presenting 26lower values, being\LED similar to both. . Evaluating the groups after enzymatic degradation, the same behavior is observed. All groups were influenced by enzymatic degradation (p <0.05), with lower resistance values after challenge. Therefore, the use of violet LED showed chromatic alteration, however, to a lesser extent than the use of peroxide-based gels. There were no changes in mechanical and adhesive properties, however, there was less cohesive collagen resistance after gel treatment, as well as after enzymatic degradation in all groups evaluated.after enzymatic degradation in all groups evaluated. (AU)

• FAPESP's process: 17/07000-7 - Dental bleaching with violet light: effects on chromatic change, bonding strength, hybrid layer nanohardness and collagen strength
• Grantee: Ana Carolina Souza Barboza
• Support Opportunities: Scholarships in Brazil - Master