The effect of different electronic toothbrushes on the surface properties of resin- based restorative materials used in pediatric dentistry

Aim: The aim of this study was to compare the changes in surface roughness of the compomer Dyract XP and the microhybrid composite Filtek Z250 after pH cycling and subsequent brushing with toothbrushes employing different mechanisms of action. Materials and Methods: A total of 96 disc-shaped specimens (8 mm in diameter, 2 mm in thickness; n=8) were prepared from Filtek Z250 and Dyract XP. The specimens were divided into control groups stored in distilled water and experimental groups subjected to a 10-day pH cycling protocol. Brushing procedures were performed using a brushing simulator operating under a 2 N load along with a custom-designed mechanical setup, simulating one year of brushing. Oral-B Stage manual, Oral-B Vitality Kids, and Oral-B iO 7 electronic toothbrushes were used together with a children's toothpaste diluted at a ratio of 1:2. Surface roughness (Ra) measurements were obtained with a profilometer at baseline, after pH cycling and after brushing. Selected specimens were further examined using SEM and EDS analyses. Data were analyzed using GLM and Tukey tests (p<0.05). Results: At baseline, the compomer exhibited significantly higher Ra values than the composite (p<0.001). pH cycling increased the Ra values of both materials, with a more pronounced effect in the compomer group (ΔRa=0.025 μm; p<0.001). Following brushing, a significant difference was observed among toothbrush types (p<0.001); the iO produced the highest, whereas the Stage produced the lowest ΔRa values. The greatest increase in roughness was found in the compomer group after pH cycling followed by brushing with the iO (ΔRa=0.190 μm), while the lowest increase was recorded in the composite group stored in distilled water and brushed with the Stage (ΔRa=0.050 μm). Conclusion: pH cycling and brushing procedures increased the surface roughness of both restorative materials. The compomer demonstrated higher roughness values compared to the composite, and electronic toothbrushes caused a more pronounced roughening effect than the manual toothbrush. Keywords: Composite Resin, Electronic Toothbrush, Surface Roughness