Abstract
Dentifrice abrasiveness and brushing time may increase color change (∆E) and surface roughness (∆Ra) of resin composites. This study aimed to evaluate the effect of mechanical brushing time of dentifrices with different abrasiveness on ∆E and ∆Ra of nanofilled (Z350, 3M ESPE) and nanohybrid (Tetric N-Ceram, Ivoclar Vivadent) resin composites. Sixteen specimens (12 mm diameter x 2 mm thick) were fabricated using a white Teflon matrix of each resin composite and a ceramic (IPS e.max Ceram, Ivoclar Vivadent), used as control. After initial color readouts on white backgrounds (Spectrophotometer PCB 6807, Byk Gardner), with D65 standard illuminant, and surface roughness (Rugosimeter Surfcorder SE 1700, Kosalab) with cut-off=0.8 mm and speed=0.25 mm/s, specimens were assigned (n=8) according to the abrasiveness of the dentifrices: RDA* 68 (Colgate) and RDA* 180 (Colgate Total Plus Whitening). Specimens were submitted to mechanical brushing (58,400 cycles) and after every 14,600 cycles (1 year of brushing by a healthy individual), new color and surface roughness readouts were taken. Color stability was calculated by CIEDE2000. Data were analyzed by 3-way repeated measures ANOVA and Bonferroni test (p<0.05), and demonstrated that the dentifrice abrasiveness (p=0.02) and brushing time (p<0.0001) affected the ∆E of nanofilled resin composite. There was no difference on surface roughness of materials (p=0.6752) or brushing time (p=0.7997). In conclusion, the longer the brushing time and dentifrice abrasiveness, the greater the color change of the nanofilled resin composite. The surface roughness was not influenced by dentifrice abrasiveness.
Highlights
The quest for esthetics by both patients and dentists has led to the continuous improvement of Dentistry as regards innovations in restorative and rehabilitating materials and/ or techniques, leading to restorations with an appearance closer to natural teeth
The greater dentifrice abrasiveness, the greater the color change (p
This study evaluated the color stability and surface roughness of two types of resin composites and a ceramic submitted to mechanical brushing with dentifrices of RDA* abrasiveness 68 and 180 for up to 58,400 cycles, simulating 4 years of clinical brushing
Summary
The quest for esthetics by both patients and dentists has led to the continuous improvement of Dentistry as regards innovations in restorative and rehabilitating materials and/ or techniques, leading to restorations with an appearance closer to natural teeth. The characteristics of simulating dental structure color, translucence and surface smoothness has made resin composite the first choice among the restorative materials used in Dentistry. In the chronology of resin composite development, a constant search for improvements in the physicalmechanical and chemical properties as well as esthetics has been observed. The roughness of a restoration concerns the finest surface irregularities that occur due to the characteristics of material (1), and the restorative (6) and polishing procedures (5,6). The chemical structure of resin composite - type of used oligomers or monomers, concentration/types of activators, initiators, inhibitors, oxidation of double carbon links and the particle/resin matrix bonding system (2,3), and filler particle characteristics have a direct impact on the surface roughness and staining of the resin composite (2)
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