Effect of different polishing systems and speeds on the surface roughness of resin composites

Impact of repair protocols on the bond strength to composite resin

This study evaluated the impact of different repair protocols on a composite resin substrate using distinct bonding agents submitted or not to artificial aging. Unopened sets of a single-step universal adhesive system (UA) and silane-coupling agents, a single-step pre-hydrolyzed (PH) or a two-step immediately hydrolyzed (IH), were used. Half of the sets were subjected to artificial aging being stored at 48 °C for 30 days, while the other half remained unaged. The composite resin substrates were prepared and aged in distilled water, sandblasted (Al2O3), and cleaned. Then the different repair protocols were applied according to the groups. UA was used without a previous silane layer, while PH and IH were applied followed by a single-step etch-and-rinse adhesive system. Adhesive systems were light-activated, and four composite resin cylinders were formed over the substrate. After 24 h, the specimens were subjected to microshear bond strength (μSBS) test and failure mode analysis. The μSBS data were subjected to two-way ANOVA followed by Tukey HSD; Kruskal-Wallis analysis was used for failure mode distribution (α = 0.05). After aging the products, UA showed higher bond strength, while PH had significantly lower results, and IH showed no significant differences (p = 0.157). No significant differences were found for bond strength among the repair protocols when using non-aged products (p > 0.05). The protocols using UA and IH showed no significant differences between aged and non-aged bottles, whereas PH exhibited lower bond strength when comparing aged and non-aged products. More cohesive failures were observed in the resin substrate for the IH group without aging.

Effect of Polishing Systems on the Surface Roughness and Color Stability of Aged and Stained Bulk-Fill Resin Composites

The aim of this study is to investigate how two different polishing techniques affect the color stability, surface roughness, and changes in surface morphology of aged and coffee-stained bulk-fill resin composites. A total of 112 disc-shaped samples were prepared using Omnichroma Flow Bulk (OB), Charisma Bulk Flow One (CB), Estelite Bulk Fill Flow (EB), and Estelite Sigma Quick (control). Samples were divided into two subgroups (n = 16) and aged using thermocycling. A profilometer was used to measure the surface roughness (Ra) and a spectrophotometer was used for color stability (ΔE00). The EB group had the highest Ra values both before aging (disc: 0.23 ± 0.05, twist: 0.42 ± 0.05) and after aging (discs: 0.28 ± 0.04, twist: 0.46 ± 0.05). The OB group had the highest ΔE00 values before and after aging (discs: 3.06 ± 0.54, twist 3.05 ± 0.41) and the highest after coffee-staining (discs: 3.75 ± 0.70, twist: 3.91 ± 0.57). Re-polishing reduced the ΔE00 values in all materials but did not restore all to clinically acceptable levels. According to the results of this study, it can be concluded that the surface roughness and color stability of resin composites are notably influenced by the polishing technique, aging process, and coffee staining. Specimens that were polished using the multi-stage Super-Snap discs consistently exhibited smoother surfaces across all bulk-fill resin composites compared to those polished with the two-stage Diacomp plus Twist.

Comparative study on the effects of different polishing methods on tooth surface microstructure and roughness following initial periodontal treatment

OBJECTIVE

To investigate the effects of different polishing methods on the surface microstructure and roughness of teeth following initial periodontal treatment.

METHODS

Teeth were divided into three groups (silica onegloss, polishing disc, and polishing strip) in vitro. Tooth surface microstructure was characterized via scanning electron microscopy. Roughness was measured by profilometry and laser scanning confocal microscopy (LSCM). According to the in vitro results, one group was chosen for further clinical trials. Effects of the chosen polishing method on patient plaque control and satisfaction were assessed via plaque staining and visual analog scale (VAS).

RESULTS

Electron microscopy results revealed that the polishing disc group had smoother roots and crowns than did the other two groups. Roughness analysis revealed that the crown roughness with the polishing disc and silica onegloss was lower, and the root roughness with the polishing disc was the lowest (p < .05) The LSCM results showed that the pigment deposition depth with the polishing disc and silicon onegloss in the crowns and roots were significantly lower than those with the other two methods (p = .000). The polishing effect of the polishing disc was best among the three groups. Clinical trials were performed to verify the polishing disc effects. Plaque staining results showed that the decrease in plaque in the polishing disc group was greater than that of the rubber cup group (p = .020), which was similar to the results of LSCM. The VAS results showed that the polishing disc made teeth feel smoother, similar to the results of the roughness detection, and the procedure was more comfortable (p < .05). However, there was no significant difference between the two groups regarding foreign body sensation during pronunciation (p = .178).

CONCLUSION

Combining in vitro and in vivo evaluations, the use of a polishing disc following periodontal treatment yielded superior polishing effects on teeth and was better accepted by patients.