Influence of irradiated dentin, biofilm and different artificial saliva formulations on root dentin caries development

Abstract

Abstract Purpose To evaluate the influence of radiation as well as of new formulations of artificial saliva on the development of root caries lesions. Methods Bovine root samples were divided into: irradiated (70 Gy) dentin or not; the type of biofilm (from irradiated or non-irradiated patients) and the type of artificial saliva (for the condition irradiated dentin/biofilm): Saliva A (inorganic); Saliva A + 1mg/ml hemoglobin; Saliva A + 0.1mg/ml cystatin; Saliva A + hemoglobin + cystatin; Bioextra (positive control) and water (negative control) (n = 12/group). Biofilm was produced using human biofilm and McBain saliva (0.2% of sucrose, 37o C and 5% CO2); the treatments were done 1x/day, for 5 days. Colony-forming units (CFU) counting was performed; demineralization was quantified by transversal microradiography. Two-way ANOVA/Bonferroni or Sidak test for the comparison between biofilm x dentin and ANOVA/Tukey or Kruskal-Wallis/Dunn for comparing artificial saliva were done (p < 0.05). Results The type of biofilm had no influence on CFU and demineralization. Sound dentin under control biofilm presented the lowest Lactobacillus ssp. and Streptococcus mutans CFU and the lowest mean mineral loss (R) (25.6 ± 2.2; 23.7 ± 2.9%) compared to irradiated dentin (26.1 ± 2.8; 28.1 ± 3.3, p < 0.004) for both types of biofilms (irradiated and no irradiated, respectively). Bioextra was the only one that reduced R (10.8 ± 2.5%) and LD (35 ± 15µm) compared to water (17.3 ± 3.3%, 81 ± 18µm, p < 0.0001). Conclusion Irradiation of dentin has impact on caries development; none of the experimental saliva was able to reduce its occurrence.