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

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 10 mm and 2 mm (n = 15). For the DTS measurement, Split stainless steel moulds were used to make disk-shaped specimens of 6 mm diameter and 2 mm 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 300 gm with a dwell time of 15 s at 7, 30, and 90ds after storage. DTS was measured after 30ds at a cross head speed of 0.5 mm/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 48.7 MPa for the GA-F and 30.6 MPa 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.