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Standard Test Method ASTM D 7998-19 for the Cohesive Strength Development of Wood Adhesives
Published on: May 17, 2020
The effect of microstructural, compositional, and rheology-based properties of universal adhesive systems on bond
Fikri Öcal1, Ayşe Karabaş2, Buse Çebi Gül2
1Inonu University, Faculty of Dentistry, Department of Restorative Dentistry, Malatya, Turkey.
Objective:
The aim of this study was to compare the rheological parameters, hybrid layer thicknesses, inorganic filler contents determined by thermogravimetric analysis (TGA), and elemental compositions obtained by energy-dispersive X-ray spectroscopy (EDX) of five different universal adhesives (G-Premio Bond [GPB], Clearfil Universal Bond [CUB], Prime Bond Universal [PBU], OptiBond Universal [OBU], and Gluma Bond Universal [GBU]) and to evaluate the relationship of these parameters with microtensile bond strength.
Materials And Methods:
Universal adhesives were applied to dentin specimens obtained from human permanent teeth. Rheological properties were measured with an oscillatory rheometer (0.3 mm gap, 2 Hz, 23 °C) in terms of viscosity, storage modulus, and loss modulus. Adhesive layer thicknesses were measured under a scanning electron microscope at × 1000 magnification, inorganic filler ratios were determined by TGA (30-600 °C), and elemental compositions were assessed by EDX. In addition, microtensile bond strength tests were performed, and the obtained values were compared with rheological, morphological, and chemical parameters.
Results:
Rheological analysis revealed that CUB exhibited the highest complex viscosity and modulus values, while PBU showed the lowest (p < 0.05). CUB produced the thickest adhesive, whereas PBU had the thinnest. TGA results indicated that OBU had the highest inorganic filler content, and PBU the lowest. Mechanical testing showed that OBU achieved the highest bond strength, while PBU demonstrated the lowest (p < 0.05). Despite showing no significant elemental differences in EDX analysis, GBU, together with GPB, presented the second-highest bond strength.
Clinical Significance:
Microstructural features, compositional characteristics, and rheology-based properties of universal adhesives are important factors influencing both bond strength and adhesive layer formation, and evaluating these parameters together may contribute to more predictable clinical outcomes.
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