Abstract
The effects of tooth brushing could affect the long-term esthetic outcome of composite restorations. This study evaluated the effect of two different emission spectrum light-curing units on the surface roughness, roughness profile, topography and microhardness of bulk-fill composites after in vitro toothbrushing. Valo (multiple-peak) and Demi Ultra (single-peak) curing lights were each used for 10s to polymerize three bulk-fill resin composites: Filtek Bulk Fill Posterior Restorative (FBF), Tetric EvoCeram Bulk Fill (TET) and Surefil SDR Flow (SDR). After 30,000 reciprocal strokes in a toothbrushing machine, the roughness profile, surface roughness, surface morphology, and microhardness were examined. Representative SEM images were also obtained. When light-cured with the Demi Ultra, SDR showed the most loss in volume compared to the other composites and higher volume loss compared to when was light-cured with Valo. The highest surface roughness and roughness profile values were found in SDR after toothbrushing, for both light-curing units tested. FBF always had the greatest microhardness values. Light-curing TET with Valo resulted in higher microhardness compared to when using the Demi Ultra. Confocal and SEM images show that toothbrushing resulted in smoother surfaces for FBF and TET. All composites exhibited surface volume loss after toothbrushing. The loss in volume of SDR depended on the light-curing unit used. Toothbrushing can alter the surface roughness and superficial aspect of some bulk-fill composites. The choice of light-curing unit did not affect the roughness profile, but, depending on the composite, it affected the microhardness.
Highlights
The surface of resin-based restorative materials can be negatively affected by bacterial biodegradation or by salivary enzymes,[1,2,3] and occlusal and toothbrushing induced wear.[4,5] Previous studies have shown that toothbrushing can increase the surface roughness and alter the surface topography of resin composites,[6,7] which can increase the formation of biofilm on the tooth.[8]
Surface roughness (Sa) Table 2 reports the mean surface roughness (Sa) of both unbrushed and brushed areas of the resin composite disks that had been light-cured with the two light-curing unit (LCU)
Toothbrushing had a significant effect on the Sa for all groups (p < 0.05), except for Filtek Bulk Fill Posterior Restorative (FBF) that had been light-cured with Demi Ultra
Summary
The surface of resin-based restorative materials can be negatively affected by bacterial biodegradation or by salivary enzymes,[1,2,3] and occlusal and toothbrushing induced wear.[4,5] Previous studies have shown that toothbrushing can increase the surface roughness and alter the surface topography of resin composites,[6,7] which can increase the formation of biofilm on the tooth.[8]. Both of these factors can negatively affect the long-term esthetic outcome of the resin composite restorations
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