Chlorhexidine effect on rehydration of irradiated dentin with Er:YAG laser after aging

Author(s)

Daniel Galafassi

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2012-02-03

Examining board members

Silmara Aparecida Milori Corona; Bruno Carlini Junior; Vinícius Rangel Geraldo Martins; Fernanda de Carvalho Panzeri Pires de Souza; Camila Tirapelli

• Advisor: Silmara Aparecida Milori Corona

Abstract

This in vitro study evaluated the bond strength of dentin prepared with Er: YAG laser or turbine, rehydrated with chlorhexidine or deionized water after artificial saliva storage and thermocycling. One hundred twenty human third molars were sectioned in order to expose the dentin surface (n=10). The specimens were equally and randomly divided according to treatment [Er:YAG laser + deionized water rehydration (LW), Er:YAG laser + chlorhexidine 2% rehydration (LC), bur on high-speed turbine + deionized water rehydration (BW) and bur on high-speed turbine + chlorhexidine 2% rehydration (BC)]. After dentin preparation, the specimens were etched with 35% phosphoric acid, washed and dried with air. The dentin rehydration method was performed with deionized water or chlorhexidine 2% by applying 1.5!L of each solution. An etch and rinse adhesive system was then applied and the samples were restored with a composite. In each group, the specimens were sub-divided in accordance with the aging method [24 hours artificial saliva storage, no thermocycling (NA); 6 months of artificial saliva storage, 12.000 thermocycling (6A); 12 months of artificial saliva storage, 24.000 thermocycling (12 A)]. After each aging period, each tooth was sectioned in order to obtain 4 sticks with a cross-sectional area of 1.0 mm2, which were submitted to microtensile test using the Universal Test Machine (0.5 mm/min). For the adhesive interface analysis by SEM, 36 healthy third molars (n=3) were restored and aged as the protocol used for the adhesive test. The two-way ANOVA showed no significant differences for the interaction between the factors and for the aging factor. Tukey test 5% showed that the LC group had the lowest bond strength values. The adhesive interface analysis by SEM showed that the irradiated groups presented irregular hybrid layer and cracks and the aging did not affect the adhesive interface morphology. The rehydration with chlorhexidine negatively influenced the bond strength of the preparation with the Er:YAG laser. The artificial saliva aging and thermocycling did not interfere with dentin bond strength. (AU)

• FAPESP's process: 08/09042-0 - EFFECT OF CHLORHEXIDINE ON HYBRID LAYER PRESERVATION AND BOND STRENGTH ON DENTIN PREPARED WITH ER:YAG LASER: IN VITRO STUDY
• Grantee: Daniel Galafassi
• Support Opportunities: Scholarships in Brazil - Doctorate