EFEITO DO NAOCL A 10% E DA APLICAÇÃO DO COMPÓSITO DE BAIXA VISCOSIDADE SOBRE A RESISTÊNCIA DA UNIÃO COMPÓSITO-DENTINA / EFFECT OF NAOCL 10% AND THE APPLICATION OF LOW-VISCOSITY COMPOSITE ON RESIN/DENTIN BOND STRENGTH

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The aim of this in vitro study was to evaluate the effect of NaOCl 10% as dentin superficial treatment and the application of a low-viscosity composite (LVC) on resin/dentin bond strength. Twenty human third molars, recently extracted, were divided in four experimental groups. The occlusal enamel was removed with a mechanical grinder perpendicular to the long axis of the tooth to expose a flat dentin surface. The teeth were ground flat using 600 grit SiC sandpaper under copious water cooling. A steel matrix with a three-dimensional shape of a trunk of pyramid was confectioned with 5 mm in smaller base side, 6 mm in biggest base side, and 5 mm of height. This matrix was positioned in the center of the flat surface, with the smaller base in close contact with the dentine. Resin walls of 3 mm height were made around of the matrix forming a Class I cavity with dimensions of 5 X 5 X 3 mm of depth (c-factor @ 4.5). The cavities were restored in accordance with 4 followings protocols: G1 (SB), dentin etching + application of the Single Bond adhesive; G2 (NaOCl +SB), dentin etching + application of NaOCl 10% solution + Single Bond adhesive; G3 (SB+FF), superficial dentin etching + application of the Single Bond adhesive + application of the Filtek Flow low viscosity composite; G4 (NaOCl+SB+FF), dentin etching + NaOCl 10% + Single Bond adhesive + Filtek Flow. The cavities were restored with TPH Spectrum composite, in a bulk-filling increment. The teeth were prepared for microtensile bond strength (μTBS). Each sample was sectioned parallel to long axle of the tooth in the mesio-distal and buccal-lingual directions, with thickness of 0,8mm. Thus, were obtained approximately 6 bonded beams specimens of the cavity pulpal floor. The specimens were tested in a Universal Testing Machine (SHIMADZU) in a traction cross-head speed of 0,5mm/min, until fracture. The data were analyzed using a two-way ANOVA and Bonferronis Test for multiple comparisons at the 0.05 significance level. There was no statistical significant difference between adhesive techniques. Statistical significant differences were verified among μTBS means of the LVC associated groups and the LVC no associated groups. The G4 (28.0 MPa) showed the highest μTBS means without statistical significant difference of G3 (26.6 MPa). While, G2 (12.3MPa) showed the lower μTBS mean without statistical significant difference of group G1 (15.9 MPa). There were lost of beams specimens in tooth sections, and was detected a negative Spearmans correlation between beams lost and bond strength values. The use of NaOCl 10 % had no influences on the μTBS. However, the use of LVC, as intermediate material, can provide a stress absorving layer, whereby increasing the resin/dentin bond strengths.

ASSUNTO(S)

desproteinização resistência de união compósito de baixa viscosidade bond strength desproteinization odontologia low-viscosity composite

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