Selective stepwise caries removal in primary teeth: a microbiological assessment on surviving microbiota

Abstract

Partial caries removal performed by the stepwise treatment has a high rate of clinical success and promotes a reduction of microorganisms in carious dentin. However, the adaptive behavior of these cloistered bacteria is not entirely clear. Aim: This study aimed to evaluate the carious dentin and quantify the microorganisms Streptococcus mutans and Lactobacillus acidophilus at the first intervention and after 90 days, assessing the acidogenicity and aciduricity of these bacteria isolated from the lesions. Methods: Twenty patients presenting deep caries lesion in primary molars eligible to receive the stepwise treatment were selected, dentin samples were collected in two different moments: in the first intervention, just after partial caries removal; and in the second intervention, during the reopening of the cavity (90 days after the temporary sealing of the lesion). The samples were processed for microbiological analyses via culture, identification and quantification. The bacteria isolates were subjected to phenotypic tests of acidogenicity and aciduricity. Dentin consistency and color was also recorded by a calibrated examiner. Data were statistically analyzed. Results: There was a reduction in the number of viable microorganisms while dentin rehardening and browning was noted (p<.05), but no change occurred in the acidogenicity and aciduricity properties of Streptococcus mutans and Lactobacillus acidophilus over time. Conclusion: Thus, the stepwise treatment promoted clinical changes as darkening and hardening of carious dentine and promoted a reduction in the number of viable microorganisms, but no influence was found on the phenotypic characteristics of acidogenicity and aciduricity of the species analyzed after 90 days.