Avaliação da influência de métodos de descontaminação após contaminação com sangue em diferentes momentos do processo adesivo

Abstract

Contamination while restoration procedures are carried out is mentioned in literature as a very frequent event, besides that, there are only a few papers which value this contamination influence in adhesion and possible decontamination methods to be carried out under such an occurrence. So, the aim of this study was to evaluate the influence of decontamination protocols upon dye leakage and push-out bond strength of a dentin adhesive system. It was used a hundred thirty five bovine incisors, which had their labial surface ground to obtain a flat dentine surface where standardized cylindrical cavities were made and they were divided in three groups: A) control without contamination (n = 15); B) contamination prior to the adhesive light activation (Adper Single Bond 2 3M ESPE) (n = 60) and C) contamination after the light activation (n = 60). After the contamination the cavities were divided (n = 15) according to the protocol used: 1) absorbent paper; 2) water; 3) conditioning with phosphoric acid or 4) sodium hypochlorite at 10%. The cavities were restored with the composite (Filtek Z250 3M ESPE), applied to only one increment. After 24 hours the restorations were polished and the specimens were subjected to thermal cycling (500 cycles/5o C a 55oC/30s). The exposure of the stained margins was done through the use of 2% methylene blue dye (pH = 7.0) and digital measurement of the restorations. The specimens cavity floor was ground, exposing the restoration, and they were submitted to the extrusion test (push out) in a universal testing machine. To statistics analysis it was used ANOVA according to two criteria (moment and protocol) and Tukey s test. In the marginal sealing evaluation there was significant statistics in the moment factor (p<0.001) and also in the interaction moment x protocol (p<0.008). The percentage average of stained margins found after light activation was statistically higher than the ones found prior to the light activation (p<0.001). In group B the conditioning protocol showed a percentage average of stained margins statistically higher than the water group (p<0.003), and the paper and hypochlorite groups demonstrated intermediate values. Comparing to group C protocols, it was not detected significant differences. Relating to the extrusion resistance, only the moment factor was statistically significant (p<0.001), while group B values were statistically higher (p<0.05) than the group C ones (5.32+3.03 and 3.4+1.92 MPa respectively). All protocols demonstrated resistance values similar to the control values. Higher resistance values were related to lower values of stained margins. It was concluded that blood contamination after light activation of the adhesive system had an adverse effect in the sealing ability of composite restorations and the different decontamination protocols generally produced similar results