The Effect of Resin Infiltration Technique on the Calculated Color Change of Demineralized Lesions of Different Severities
To assess the color change of demineralized enamel lesions of different severities after resin infiltration using both clinical spectrophotometry and digital photography. Sixty sound human premolars were randomly divided into 3 groups according to the demineralization level. All the teeth were immersed in a demineralizing solution of a pH adjusted to 4.4 at 37°C. Three levels of demineralization were obtained (D1 shallow, D2 moderate, D3 deep) according to the demineralization time. The demineralized area was then infiltrated by low-viscosity resin (ICON, DMG, Germany). Two instrumental methods were utilized to assess the color difference, a clinical spectrophotometer and digital photography at three time points (sound, demineralized, and infiltrated enamel) to calculate the color difference between sound and demineralized enamel (ΔE1) and between sound and infiltrated enamel (ΔE2). Statistical analysis was performed by ANOVA, followed by Tukey's post hoc test. The correlation was analyzed using linear regression. Two-way ANOVA showed statistically significant differences for both levels of the study (p≤0.05). The color change (ΔE1) and (ΔE2) for different demineralization levels showed statistically significant differences between all groups. For both clinical spectrophotometry and digital photography, D3 showed the highest difference followed by D2 and then D1. As for (ΔE1) calculations, digital photography had a significantly higher difference than spectrophotometry for the D1 group (5.47±0.93 vs 2.78±0.58). As for (ΔE2) digital photography had a statistically significantly lower difference than spectrophotometry (5.55±1.05 vs 6.48±0.76) for the D3 group. Color correction after resin infiltration is affected by the demineralization level of enamel. Clinical spectrophotometry and digital photography can detect similarly the color change of demineralized enamel after resin infiltration in shallow and moderate demineralization. However, in deep demineralization clinical spectrophotometry tends to exaggerate the color change compared to digital photography.SUMMARY
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Different demineralization levels: (a) shallow demineralization D1, (b) moderate demineralization D2, and (c) deep demineralization D3.
Resin infiltration: (a) ICON etch, (b) ICON dry with the masking effect preview, (c) ICON infiltrant, (d) resin infiltrant before curing, (e) light polymerization of ICON infiltrant, and (f) polishing of the infiltrant surface.
Scatter plot graph showing linear regression between the color difference measured ΔE1 and ΔE2 by digital photography and clinical spectrophotometry within all demineralization levels.
Line graph showing the change in the L value in all groups between sound enamel, demineralized enamel, and infiltrated enamel when measured by both clinical spectrophotometer and digital photography. S: Clinical spectrophotometry, P: Digital photography.
Scatter plot showing the relation between ΔE2 and the ΔE00 50:50% acceptability threshold levels for each demineralization level within each device.
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