Detection of artificial enamel caries-like lesions with a blue hydroxyapatite-binding porosity probe.

OBJECTIVES: This in vitro study investigated the ability of a blue protein-based hydroxyapatite porosity probe to selectively detect artificial enamel caries-like lesions of varying severities. METHODS: Artificial caries-like lesions were formed in enamel specimens using a hydroxyethylcellulose-containing lactic acid gel for 4/12/24/72 or 168 h. One untreated group was used as a control. The probe was applied for 2 min and unbound probe rinsed off with deionized water. Surface color changes were determined spectrophotometrically (L*a*b* color space) and with digital photography. Lesions were characterized using quantitative light-induced fluorescence (QLF), Vickers surface microhardness, and transverse microradiography (TMR). Data were analyzed using one-way ANOVA. RESULTS: Digital photography did not reveal any discoloration in unaffected enamel. However, all lesions stained blue with color intensity positively correlated with demineralization times. The color data reflected similar trends: lesions became significantly darker (L* decreased) and bluer (b* decreased), while overall color differences (DeltaE) increased significantly after probe application (4-h lesion, mean+/-standard deviation: DeltaL*=-2.6 +/- 4.1/Deltab*=0.1 +/- 0.8/DeltaE=5.5 +/- 1.3 vs. 168-h lesion: DeltaL*=-17.3 +/- 1.1/Deltab*=-6.0 +/- 0.6/DeltaE=18.7 +/- 1.1). TMR analysis revealed distinct differences in integrated mineral loss (DeltaZ) and lesion depth (L) between demineralization times (4-h lesion: DeltaZ=391+/-190 vol%min x microm/L = 18.1 +/- 10.9 microm vs. 168-h lesion: DeltaZ=3606+/-499 vol%min x microm/L = 111.9 +/- 13.9 microm). QLF and microhardness were also able to differentiate between demineralization times. L and DeltaZ strongly correlated (Pearson correlation coefficient [r]) with Deltab* (L vs. Deltab*: r=-0.90/DeltaZ vs. Deltab*: r=-0.90), DeltaE (r = 0.85/r = 0.81), and DeltaL* (r=-0.79/r=-0.73). CONCLUSION: Considering the limitations of this study, the blue protein-based hydroxyapatite-binding porosity probe appears to be sufficiently sensitive to distinguish between unaffected enamel and artificial caries-like lesions. CLINICAL SIGNIFICANCE: Early detection of enamel caries lesions remains one of the most critical aspects in the diagnosis and management of dental caries. This study highlighted the potential of a novel porosity probe in detecting artificial caries-like demineralization by objective means.