Objectives: Total bacteria and Lactobacilli of residual dentin were studied at baseline and after 3 months, using MI caries removal technique and glass ionomer cement (GIC) restoration with or without ultrasonic (US) command set to improve its adhesive properties.
Methods: Sixty carious teeth (32 patients) received standardized MI caries removal (polymer bur) and dentin biopsy (#4 round bur) of affected dentin followed by restoration (GIC or GIC/US). Three months after baseline, a second dentin biopsy was taken after restoration removal. Total bacterial DNA and RNA was quantified by real-time PCR and RT-PCR using universal and Lactobacilli specific primers. The number of bacterial cells was calculated based on standard curve with known cell numbers. Statistical analysis was performed using SAS repeated measurement procedure.
Results: Total bacterial DNA and RNA at baseline and 3-month re-entry (P>0.05) was not statistically different for both tested groups. Changes after three months were similar (P>0.05). Lactobacilli DNA was detectable in 44.4% of GIC group at both evaluation intervals. The GIC/US group showed a moderate reduction (P=0.066) of samples presenting detectable Lactobacilli levels: 46.4% (baseline) and 35.7% (3-month recall). No Lactobacilli RNA was detected in both groups at both intervals.
Conclusion: The overall bacterial DNA and metabolic activity of total bacteria was not changed after 3 months. Cariogenic bacteria, present in part of the samples, showed no metabolic activity. The use of ultrasound as a command set only slightly influenced the pattern of the entombed microflora.