Surface and bulk properties of dental resin- composites after solvent storage

Abstract

ObjectivesTo investigate the surface micro-hardness and the diametral tensile strength (DTS) of bulk-fill and conventional resin-composites after storage in food simulating solvents. MethodsEight materials were investigated. For the micro-hardness measurement, Teflon mould with an internal dimensions of 10mm and 2mm (n=15). For the DTS measurement, Split stainless steel moulds were used to make disk-shaped specimens of 6mm diameter and 2mm thickness (n=15). Materials were subdivided in to three groups (water, 75% ethanol/water and MEK). Micro-hardness measurements were made under a load of 300gm with a dwell time of 15s at 7, 30, and 90ds after storage. DTS was measured after 30ds at a cross head speed of 0.5mm/min. ResultsThe storage time and type of solvent had a significant influence on the micro-hardness. MEK showed more drastic reduction in the material micro-hardness with an exception of G-aenial universal flo (GA-F) which showed similar results in water/ethanol and MEK. DTS values of materials stored in water ranged from 48.7MPa for the GA-F and 30.6MPa for Ever X posterior (EXP). Generally, the results are observed to decrease with increasing solvent power, except for GA-F. SignificanceBulk-fill materials showed no superior results compared with the other materials. For the bulk-fill materials that are designed to be used as a base, their penetration by the solvents may be shielded and thus the changes observed in this study may not be of clinical importance.