Abstract
The push-out (PO) test and the diametral compression (DC) test were performed to compare the merits of two post-dentin bond strength measurement methods. Compared with the push-out test, the disk in DC provided post-dentin bond strength measurements that were more precise. The load-displacement curves from the DC test were much smoother and more linear up to the point of fracture when compared to those from the PO test. Compared to the PO test, DC is easier to perform for determining the bond strength between posts and dentin. No specimen alignment is needed in the DC test, and it produces a smaller standard deviation in the measured bond strength. The main disadvantage of the DC test, however, is that finite element analysis (FEA) is required to calculate the bond strength. The shear bond strength given by the PO test based on the simple formula is not valid, though, and the peak failure load is dependent on friction at the post-dentin interface.
Highlights
Teeth with extensive loss of coronal hard tissue after endodontic treatment require the placement of posts inside the root canals to support the restorations above[1]
The results showed that the tensile bond strengths measured by the diametral compression (DC) test (15.39 ± 2.00–20.01 ± 2.76 MPa) were higher than the shear bond strength determined by the PO test (5.14 ± 2.66–8.04 ± 3.93 MPa) for both of the materials and pretreatments used in this study (p = 0.000)
The DC test, as an indirect tensile test, induces a tensile stress in the direction transverse to the applied compressive load which splits the round specimen into two halves along the loading diameter and part of the post-dentin interface
Summary
Teeth with extensive loss of coronal hard tissue after endodontic treatment require the placement of posts inside the root canals to support the restorations above[1]. The PO test is commonly used for evaluating the bond strength of intracanal filling materials[8,9,10]. FEA has shown that the fracture-initiating stress is tensile rather than shear, invalidating the formula used to calculate the bond strength. The measurements it produces have a large standard deviation[11,12]. The purpose of this study was to compare the merits of the DC and PO tests and to try to offer an appropriate method to measure the bond strength of intracanal post with root dentin. The null hypothesis was that there was no significant difference between the two methods to measure the post-dentin interfacial bond strength
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