Dentin bond strength measurement: experiments and theoretical analysis
Date Issued
2012
Date
2012
Author(s)
Huang, Shih-Hao
Abstract
The success of endodontic and prosthodontic treatments depends on the adequate adhesion between restoration and teeth. Among existing methods, push-out bond test had been widely used to measure the bond strength of intracanal filling materials and dental post. However, the suitability of applying push-out bond test to dental research was rarely discussed. The purposes of this work were to examine the suitability of push-out bond test, and provide a novel technique to measure the bond strength of intracanal materials.
In the first part, we used a 3D finite element with cohesive zone model to simulate the push-out bond procedure. The influences of interfacial properties and experimental setups on the force needed to push the filler out were examined. We found that push-out bond test is more like to measure the retentive ability of filler, rather than the interfacial bond strength only. When using in intracanal filling materials with lower elastic modulus, the punch diameter should be standardized, which the suggesting range is between 0.65 to 0.9 times of filler diameter. It is beyond the limitation of test to compare the bond strength of root canal filling materials by push-out bond test. Therefore, an alternative test method to measure the bond strength is necessary.
In the second part, we provided a novel dentin bond strength measurement technique, which using the resin composite disks, containing a slice of dentin with intracanal post in the center, under diametral compression until fracture. The feasibility of this technique to measure the post-dentin interfacial bond strength was evaluated by acoustic emission (AE) and digital image correlation (DIC). We found that the failure of the composite disk in diametral compression was shown to be caused by debonding at the post-dentin interface. And, the final failure load could be used directly to calculate the bond strength. The advantages of this method included simpler specimen preparation, no premature specimen failure, more consistent failure mode, and smaller variations.
In the final part of this work, we used finite element method to analyze the stress distribution and to carry out the sensitivity analysis. Progressive post-dentin interfacial debonding was also simulated to better understand the failure process observed in experiments. The mechanism of this novel method was discussed and confirmed that interfacial debonding will take place prior to fracture in the dentin, which was correspond to experimental observation. The correction factors, which can be used in conjunction with the analytical solution for traditional Brazilian disk test, were provided to facilitate the adoption of the composite disk in diametral compression for bond strength measurement.
After a serial studies on this work, we provided some suggestions and warnings in applying push-out bond test to measure the bond strength of intracanal filling materials. Also, a novel bond strength measurement technique was introduced and validated by a series of studies.
Subjects
Adhesion
Dental post
Intracanal filling materials
Bond strength
Finite element analysis
Brazilian disk
Type
thesis
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