Novel bioactive caries-detecting dye solution: Cytotoxicity, antimicrobial activity, scanning electron microscope, and stereomicroscopic analysis in diagnosis of dental caries

AIM: The aim was (1) to study the cytotoxicity of novel Bioactive Caries-detecting Dye solution (BCD) and its antimicrobial activity against Streptococcus mutans, Lactobacillus acidophilus, Actinomyces naeslundii, and Candida albicans and (2) comparative assessment of BCD and Carie-Care for efficient removal of caries (stereomicroscope) and dentin tubule occlusion (scanning electron microscope [SEM]). MATERIALS AND METHODS: For BCD cytotoxic study (direct contact method), colorimetric MTT assay, and cell line study(L929 mouse fibroblast NCTC clone 929 strain L) was performed. Xenetix 350, chitosan, nanohydroxyapatite (nHA), BCD, and Carie-Care solutions were subjected to the antimicrobial activity through blood agar well diffusion method, and the minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were determined. On 20 extracted human carious teeth a comparative pilot study was done for BCD (Group A, n = 10) and Carie-Care (Group B, n = 10), and evaluated visually and radiographically. After mechanical excavation of caries with a spoon excavator, teeth sectioned longitudinally and stereomicroscopically were evaluated (8x–40x) by two observers. The percentage of dentinal tubule occlusion was evaluated with SEM for both solutions. Statistical kappa analysis of agreement was 0.7–0.8 (P < 0.01). Mann–Whitney test ranks and Wilcoxon signed-rank test (P = 0.01) were applied. RESULTS: Cytotoxicity test revealed BCD to be nontoxic and biocompatible. Antimicrobial tests (zone of inhibition) showed BCD > chitosan > chlorhexidine > Carie-Care > Xenetix 350 > nHA. MIC and MBC values suggested chlorhexidine > BCD > Carie-Care. Stereomicroscopic analysis showed effective mechanical removal of caries in BCD without residual dye in the dentinal tubules as compared to Carie-Care. Dentinal tubule occlusion (SEM analysis) was 80%–85% for BCD and 10% for Carie-Care. CONCLUSIONS: Profound synergistic effect for BCD was observed with advantage of radiographic assessment.