Purpose: To evaluate clinically and microbiologically the effect of calcium hydroxide (CH) on carious dentin on primary teeth submitted to indirect pulp capping (IPC).
Methods: Twenty 4-7 year-old subjects with 42 treated teeth participated in the study. The treatment consisted of incomplete excavation of the demineralized dentin, application of a CH or gutta-percha (GP) layer and sealing with a resin-based composite for 4-7 months. After cavity preparation and sealing, the dentin was evaluated clinically (color and consistency) and microbiologically. Dentin samples were cultured on blood agar under aerobic and anaerobic conditions, in Mitis Salivarius agar and Rogosa SL agar.
Results: 39 teeth (20 in the CH Group and 19 in the GP Group) were reopened 4-7 months post-treatment for clinical and microbiological evaluation. In all teeth, the initial demineralized dentin was wet and soft or leathery. In the CH Group, 10% of the lesions were yellow, 80% light brown and 10% dark brown and in the GP Group, 94.7% were light brown and 5.3% dark brown. After treatment, the dentin was dry, 90% (Group CH) and 84.2% (Group GP) were dark brown. The final consistency was either leathery or hard. Three samples in the CH Group and five in Group GP changed from soft to leathery; only one sample (GP) remained leathery. 85% in the CH Group and 68.4% in GP Group turned hard after treatment. All bacterial counts decreased significantly by the end of treatment. In the CH Group, the bacterial (Log10 CFU + 1) anaerobic growth decreased from 4.84 +/- 1.31 to 1.35 +/- 1.54, aerobic from 4.09 +/- 1.04 to 0.92 +/- 1.30 and lactobacilli from 3.24 +/- 1.22 to 0.36 +/- 0.89, respectively; the mutans streptococci from 2.05 +/- 1.84 to 0.14 +/- 0.60. In GP Group, anaerobic growth decreased from 5.22 +/- 0.96 to 2.02 +/- 1.65 and aerobic from 4.23 +/- 1.37 to 1.08 +/- 1.29 and lactobacilli from 2.06 +/- 1.81 to 0.00 +/- 0.00, respectively; the mutans streptococci from 3.16 +/- 1.59 to 0.28 +/- 0.84.