Effect of saliva and blood contamination on microtensile bond strength of fibre posts to composite core

Abstract

Inadequate isolation during placement of fiber post and composite core could contaminate these materials with oral fluids. This research aimed to evaluate the effect of saliva and blood contamination on bond strength between fibre post and composite core, and methods of post decontamination. Fibre posts were divided into three groups: (i) NC – non-contaminated, (ii) S0 – saliva-contaminated and (iii) B0 – bloodcontaminated. The fibre posts were positioned in moulds, composite cores constructed around the posts, then sectioned into sticks for microtensile bond strength testing. To investigate the effect of fibre post decontamination, for each contaminant [Saliva (S), Blood (B)], the posts were decontaminated by; (i) S1, B1 – washing with water from a three-way syringe, (ii) S2, B2 – cleaning with 99.8% ethanol, (iii) S3, B3 – 3% sodium hypochlorite, and (iv) S4, B4 – 2% chlorhexidine solutions. Pre-test failures occurred in all groups except for control group NC and decontamination group S3. Microtensile bond strength was analysed through two approaches: non-parametric Kruskal-Wallis test with pre-test failures assigned value of 0 MPa, and parametric one way ANOVA for analysis of surviving specimens. Kruskal-Wallis test indicated saliva and blood contamination was significantly associated with reduced bond strength, regardless of type of contaminant (p < .001). One way ANOVA demonstrated blood contamination had a more negative effect than saliva on bond strength (p = .142). Kruskal-Wallis test found that cleaning of saliva-contaminated posts with sodium hypochlorite regained bond strength similar to that of non-contaminated posts (p = .237). None of the decontamination methods were effective in recovering bond strength of bloodcontaminated posts. The results indicated that contamination affects the bond between fibre post and composite core, and decontamination methods are not successful in cleaning the post surface to maintain the bond strength. Clinically, every effort must be taken to prevent contamination of the fibre post.