Effect of Incorporation of Hydroxyapatite Nanorods on the Rheological Properties, Micro-shear Bond Strength and Degree of Conversion of Two Dental Adhesives

Authors

1 Paper extracted from thesis titled Effect of Incorporation of Hydroxyapatite Nanorods on the Rheological Properties, Microshear Bond Strength and Degree of Conversion of Two Dental Adhesives.

2 Demonstrator of Dental Biomaterials. Faculty of Dental Medicine, Al-Azhar University (for Girls), Egypt.

3 Assistant Professor and Head of Dental Biomaterials,-Faculty of Dentistry for girls. Al azhar University

Abstract

Purpose: The purpose of this study was to evaluate the effect of incorporation ofdifferent concentrations of hydroxyapatite nanorods into two adhesives of two commercialadhesive systems in order to evaluate the effect on rheological properties, microshearbond strength and degree of conversion. Materials and Methods: One hundredtwenty specimens were used in the present study. The specimens were divided into twomain groups (n=60) according to the type of commercial adhesive used AdheSE Bond(I) and Tetric-N Bond Universal (II). Then each group was subdivided into 4 subgroups(n=15) according to the concentration of incorporated HAp nanorods 0( control), 0.2,2, 10wt%HAp nanorods (A, B, C and D, respectively). Each subgroup was furtherdivided into 3 divisions according to the type of test performed (n=5). For rheologicalproperties measurements, a rheometer was used to measure the viscosity and theviscoelastic behavior of the adhesives. For microshear bond strength testing (μSBS),the specimens were tested by using a universal testing machine. The type of failurewas determined by using scanning electron microscope. The degree of conversion wasmeasured using Fourier Transform Infrared (FTIR) spectroscopy. The data were analyzedusing one-way analysis of variance (ANOVA) and Tukey’s post hoc significancedifference tests. Differences were considered significant at p≤0.05. Two ways analysisof variance ANOVA test was used to study the statistical significance of the interactionbetween variables (material and HAp nanorods concentrations). Results: The viscosityof experimental adhesives increased gradually with increasing the concentrations ofHAp nanorods. In μSBS test, the AdheSE containing 0.2 and 2wt.% HAp nanorods producedsignificantly the highest values. Regarding degree of conversion (DC), Tetric-NBond containing 10wt.% HAp nanorods produced significantly the highest value ofDC. Conclusion: Incorporation of HAp nanorods with low concentration (0.2wt %) inAdheSE Bond had a positive impact on the bond strength. However, HAp nanorods asfillers were not suitable to be incorporated in Tetric-N Bond.

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