Rizvi, NaureenAlkheledan, Lamya2025-11-292025Harvard Stylehttps://hdl.handle.net/20.500.14154/77225A controlled in-vitro study evaluating how three everyday prophylaxis methods rubber-cup pumice, sodium bicarbonate air-polishing, and erythritol+CHX air-polishing affect the colour stability of a nanohybrid composite, quantified with ΔE00 across staged staining/polishing cycles and supported by qualitative SEM. Using a 60-specimen protocol with calibrated, cross-polarised eLAB photography and pre-registered stats, we found clinically perceptible, statistically significant differences between modalities: sodium bicarbonate gave the greatest initial discolouration but also the strongest stain removal; pumice delivered the best overall balance; erythritol was gentler but showed higher cumulative colour change after repeated cycles. The findings translate into pragmatic, tiered maintenance guidance for aesthetic composites.Air polishing is a commonly employed technique for professional mechanical plaque removal in dental patients. Although effective, evidence suggests it can increase surface roughness of composite restorations, which may in turn increase their susceptibility to staining. There remains, however, a lack of studies directly investigating the effects of different air polishing powders on the colour stability of composite resins. The purpose of this study was to evaluate the effect of air polishing with sodium bicarbonate and erythritol powder on surface characteristics and colour stability of nanohybrid composite resins, compared with no polishing and traditional pumice paste. The aim was to help inform clinical recommendations for professional mechanical plaque removal and polishing in patients who have composite restorations in aesthetic zones. Materials and methods: Sixty disc-shaped specimens of G-ænial Anterior composite (GC Corp., Tokyo, Japan) were prepared and allocated to 4 groups (n=15): control (no polishing), sodium bicarbonate air polishing, erythritol air polishing, and traditional pumice polishing. All specimens underwent immersion in tea at 37 °C for 24 hours and colour measurements were recorded at four stages, (baseline, post-staining, post-polishing, final staining) using the eLab digital colour analysis system (eLAB Prime, GmbH, Germany). Separately, one specimen was prepared for each group solely for SEM analysis to qualitatively assess surface morphology before and after polishing. Results: Significant differences in colour change (ΔE₀₀) were observed across groups (p < 0.001). Sodium bicarbonate showed the highest initial staining (T1: 13.51 ± 2.41), followed by erythritol + CHX (10.67 ± 2.34), pumice (9.77 ± 1.03), and control (7.26 ± 0.97). For stain removal (T2), sodium bicarbonate exhibited the greatest change (7.76 ± 3.53), indicating stronger abrasive action, while erythritol + CHX (5.15 ± 1.52) and pumice (5.08 ± 1.10) showed comparable effects. Cumulative colour change (T3) was highest in the erythritol + CHX group (10.57 ± 1.69), followed by the control (10.34 ± 1.10), with lower values in sodium bicarbonate (8.58 ± 0.74) and pumice (7.90 ± 1.89). SEM imaging showed smoother, more uniform surfaces with pumice, and greater surface disruption in specimens exposed to sodium bicarbonate and erythritol + CHX. Conclusions: Rubber cup polishing with pumice effectively removed stains while maintaining the lowest overall colour change out of the three polishing methods tested. Sodium bicarbonate produced the highest initial discolouration and demonstrated the greatest stain removal capacity. Erythritol resulted in the highest colour change after repeated polishing and staining. Specimens in the unpolished control group also accumulated stains over time. While changes to composite surface characteristics were observed with all polishing methods, further studies are needed to quantify these changes. Clinicians should be aware that commonly used polishing methods can affect both colour stability and surface characteristics of composite restorations.101enComposite Resinsurface Roughnessair PolishingThesis