Effect of the interfacial area measurement parameters on the push-out strength between fiber post and dentin

Abstract Purpose To verify the influence of different instruments and operators on the bonding interfacial area and on the push-out bond strength values. Material and methods Fifteen anterior human teeth ( n =15) were selected, cleaned and standardized to 15 mm length. Root canals were prepared in 12 mm and the fiber posts were cemented using the RelyX U-100 cement. Three slices were obtained per tooth ( N =45) and submitted to the push-out bond strength test. The bonding interfacial area (mm 2 ) of each specimen was calculated based on the disc slice dimensions: coronal and apical diameter and height. The bonding area of each specimen was used to calculate the bond strength (Mpa). The dimensions were analyzed by different operators, using two instruments: G1 – Operator A with a digital caliper; G2 – Operator A with a stereomicroscope; G3 – Operator B with a digital caliper; G4 – Operator B with a digital stereomicroscope; G5 – Operator C with a digital caliper; G6 – Operator C with a stereomicroscope. The mean area was submitted to inter-operator and intra-operator analyses, while the mean area and mean of bond strength were submitted to the 2-way ANOVA with repeated measures and the Tukey test ( α =0.05). Results The inter-operator kappa was 0.83 to the digital caliper and 0.91 to the stereomicroscope, while the intra-operator kappa was 0.76. The operator and the measurement instrument influenced the interfacial bonding area ( p =0.000 and p =0.001) and the push-out bond strength values ( p =0.000 and p =0.000, respectively) of the disc slices. Conclusion The final push-out bond strength values are influenced by the measuring instrument and by the measurer operator.