The Effect of Heating on Surface Microhardness of Resin-based Materials for Direct Restoration

Abstract

The aim of this study was to evaluate and to compare the surface hardness of three types of resin-based materials used for direct restoration after heating at different temperatures. A giomer (Beautifil II, Shofu Dental), a compomer (Dyract eXtra, Dentsply Sirona) and a hybrid composite resin (Gaenial Posterior, GC Corporation) were selected for this study. Twenty disk-shaped specimens of each material were heated at room temperature (21�C), at 37�C, at 50�C and at 60�C. Vickers microhardness test was performed on top and bottom surfaces using digital microhardness tester (Micro-Vickers Hardness System CV- 400DMTM, CV Instruments Namicon). The top and bottom surfaces VHN was calculated as a mean value of five determinations. Also, the microhardness ratio was calculated by dividing the top mean VHN value by bottom mean VHN value. Increased mean hardness values were recorded after heating, irrespective of resin-based tested materials. The highest hardness values were recorded after heating all three materials at 60�C, followed by the hardness recorded at 50�C, 37�C and 21�C. For top surfaces, the lowest hardness value was recorded in Dyract eXtra group when samples were warmed at room temperature and the highest hardness value was obtained in Beautifil II group when samples where heated at 60�C. For the bottom surfaces, Dyract eXtra specimens heated at 21�C presented the lowest hardness values and Beautifil II samples heated at 60�C presented the highest hardness values. On top and on bottom surfaces Dyract eXtra showed the lowest hardness values, followed by G-aenial Posterior and Beautifil II, irrespective the heating temperature.

Examining the Impact of Preheating on the Fracture Toughness and Microhardness of Composite Resin: A Systematic Review

“…The provided table (Tables 3, 4) summarizes various studies on microhardness and fracture toughness. Out of the total 29 studies included, 16 demonstrate an increase in microhardness alone [3,8,9,12,13,15,16,17,18,19,21,22,23,25,27,28], while one shows an increase in fracture toughness alone [20]. Additionally, three studies reveal no statistically significant difference in microhardness values [5,10,30].…”

Characterization of Sealing Materials by Energy Dispersive X-ray Spectrometry and Scanning Electron Microscopy

“…An study which compare the the interface between enamel surfaces at the level of pit and fissure and the sealant with different cleaning procedures, with or without acid etching show that Concise White Sealant achieves a better enamel sealing than Dyract Seal when the teeth are treated with air abrasion or air polishing followed by etching [8]. The microhydrid composite resins have a significantly higher hardness than nano-hybrid composites or compomers [9,10] and in another study on top and on bottom surfaces Dyract eXtra showed the lowest hardness values [11]. Beresescu and all considered that particular types of restoring materials should be used in particular situation, depending on the location of the surfaces and the elastic characteristics of the materials and tooth structure [12].…”

The effect of giomer’s preheating on fluoride release

“…8,9 Research on the giomer surface microhardness in previous studies, shows that preheating treatment at 60°C has a higher hardness than 37°C. 10 Another previous research, showed that preheating treatment at 60°C could lead to decreased microleakage and better marginal adaptation to composite resins. 11 Based on previous research that provides preheating treatment so as to increase mechanical strength and minimize microleakage in composites, it encourages researchers to conduct research that has never been done before to determine the effect of preheating treatment temperature on the release of giomer's fluoride.…”