IADR Abstract Archives
Characterising early erosive lesions in polished and natural human enamel
Objectives: This study investigated the application of surface profilometry, surface roughness, surface microhardness, optical coherence tomography (OCT) and tandem scanning microscopy (TSM), to characterise the textural and physical changes that occur during early acid erosion of polished and natural human enamel in vitro.
Methods: 120 enamel samples, 60 polished and 60 natural, were evenly (n=10) subjected to increasing 0.3% citric acid erosion times (0s, 10s, 30s, 60s, 120s, and 300s) and the change assessed using surface profilometry (3D step height change, µm), surface roughness (µm), and surface microhardness (KHN), and qualitatively using OCT and TSM.
Results: Mean (SD) surface roughness (μm) of polished enamel samples after acid immersion increased after 10s (0.270+0.013), 30s (0.300+0.018), 60s (0.510+0.068), 120s (0.950+0.201), 300s (1.280+0.146) and were statistically significant compared to baseline (p<0.05). However, for natural enamel samples, mean surface roughness decreased with increasing immersion time and was only statistically significant (p<0.005) at 120s (0.830+0.125) and 300s (0.800+0.140). Mean (SD) microhardness (KHN) for polished enamel decreased with increasing acid immersion period: 10s (315.9+1.82), 30s (296.0+1.32), 60s (268.7+1.39), 120s (253.6+1.39), 300s (228.5+2.65); which was statistically significant at all time points (p<0.001), and microhardness was not possible to measure for the natural surfaces. Mean (SD) 3D step height change (μm) was measurable and statistically significant for the polished but not for unpolished; measurements for polished at: 60s (0.24+0.1), 120s (1.16+0.71), 300s (2.01+0.47). Qualitative image analysis of both sample types indicated erosive change occurring at the surface level, and progressed with increasing erosion immersion time.
Conclusions: The early erosive lesion could only be characterised quantitatively and qualitatively for polished enamel samples using surface roughness, surface microhardness, OCT and TSM. However, it was unquantifiable for natural enamel samples, using existing methods, despite qualitative evidence of enamel structure alteration during early erosion.
Methods: 120 enamel samples, 60 polished and 60 natural, were evenly (n=10) subjected to increasing 0.3% citric acid erosion times (0s, 10s, 30s, 60s, 120s, and 300s) and the change assessed using surface profilometry (3D step height change, µm), surface roughness (µm), and surface microhardness (KHN), and qualitatively using OCT and TSM.
Results: Mean (SD) surface roughness (μm) of polished enamel samples after acid immersion increased after 10s (0.270+0.013), 30s (0.300+0.018), 60s (0.510+0.068), 120s (0.950+0.201), 300s (1.280+0.146) and were statistically significant compared to baseline (p<0.05). However, for natural enamel samples, mean surface roughness decreased with increasing immersion time and was only statistically significant (p<0.005) at 120s (0.830+0.125) and 300s (0.800+0.140). Mean (SD) microhardness (KHN) for polished enamel decreased with increasing acid immersion period: 10s (315.9+1.82), 30s (296.0+1.32), 60s (268.7+1.39), 120s (253.6+1.39), 300s (228.5+2.65); which was statistically significant at all time points (p<0.001), and microhardness was not possible to measure for the natural surfaces. Mean (SD) 3D step height change (μm) was measurable and statistically significant for the polished but not for unpolished; measurements for polished at: 60s (0.24+0.1), 120s (1.16+0.71), 300s (2.01+0.47). Qualitative image analysis of both sample types indicated erosive change occurring at the surface level, and progressed with increasing erosion immersion time.
Conclusions: The early erosive lesion could only be characterised quantitatively and qualitatively for polished enamel samples using surface roughness, surface microhardness, OCT and TSM. However, it was unquantifiable for natural enamel samples, using existing methods, despite qualitative evidence of enamel structure alteration during early erosion.