Chemical degradation of adhesive materials bonded to dentin substrate : mechanical and micromorphologic analysis / Degradação quimica da união de materiais adesivos ao substrato dentinario : analise mecanica e micromorfologica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The purpose of this study was to evaluate the effect of the dynamic chemical challenge pH (DES/RE solutions) and storage regimen on degradation of resin/dentin-bonding using the microtensile bond strength (µTBS) and quantify fluoride release from the adhesive system. Superficial occlusal dentin of extracted human molars was exposed and wet ground with 600-grit SiC paper. Then, teeth were randomly distributed into 2 groups according to adhesive systems (n=4): Clearfil Protect Bond (PB) (Kuraray) and Clearfil SE Bond (SE) (Kuraray). A block of composite resin TPH (Dentsply) with 6 mm thickness was bonded to the tooth with the adhesive systems according to manufacturer s instructions and each thickness with 2 mm was light cured for 40 seconds. After 24 hours in moist environment at 37oC, the specimens were sectioned perpendicular to the bonding area to obtain 1mm2 sectional area sticks, which were randomly divided into 6 groups according to storage regimen: G1 - PBI (immediate-control); G2 - PBC (pH cycling model); G3 - PBW (140 days water storage); G4 - SEI (immediate - control); G5 - SEC (pH cycling model); and, G6 - SEW (140 days water storage). After that, the sticks were submitted to microtensile bond strength (µTBS) test in a Universal machine (Instron) at a crosshead speed of 0.5mm/min. Fluoride concentration in demineralization (n=8) / remineralization (n=8) solutions and deionized water (n=23) was obtained by collecting 0,5 mL of these solutions and 0,05 mL of TISAB III, from 1 to 4 days ( De, Re and deionized water) and 30 days (deionized water). Fluoride release was detected using a fluoride-specific electrode connected to a microprocessor ion analyzer.The data were submitted to ANOVA and Tukey s tests (p<0.05) and Friedman s tests. Microtensile bond strength- µTBS (MPa) mean values were 30.4±11.6 (PBI), 29.5±9.1 (PBC), 27.1±11.6 (PBW), 28.9±11.1 (SEI), 27.1±7.6 (SEC) and 21.3±10.9 (SEW). There was no significantly statistical difference between PB and SE in all conditions of treatment (p>0.05). The PBI and SEI showed significantly higher µTBS values compared to PBW and SEW (p<0.05). The pH cycling model in the PB and SE didn´t show significantly difference on µTBS values when compared immediate and the deionized water storage for 140 days (p>0.05). Fluoride concentrations present in the DES/RE were less than 0.03125 ppm and no in deionized water, regardless of the adhesive system tested. No significantly difference was found between adhesive systems in all conditions. The 140-day water storage decreased the µTBS values from two adhesives systems.

ASSUNTO(S)

tensile strength dentin-bonding agents resistencia a tração adesivos dentinarios

ACESSO AO ARTIGO

Documentos Relacionados