Characterization of Lactobacilli isolated from carious dentin after selective caries removal and cavity sealing.

OBJECTIVE: To characterize lactobacilli isolated from residual carious dentin after selective caries removal (SCR), by observing the changes detected in their prevalence, diversity, and cariogenic potential after starvation stress caused by cavity sealing (CS). DESIGN: Lactobacilli were cultured from carious dentin lesions (n = 16 patients) treated in a clinical trial, three months before and after CS. Presumptive lactobacilli were selected, isolated, and analyzed by Gram staining. Housekeeping gene sequences were used to identify the species (groEL, rpoA, pheS, and 16S rRNA). RESULTS: N = 86 Lactobacillus spp. (n = 41 before and n = 45 after sealing) were genotyped by AP-PCR and analyzed for their cariogenic potential (acid production and acid tolerance). The proportion of lactobacilli to the total anaerobic counts was high, and a significant decrease was observed after sealing (median before sealing = 78.9; 25th-75th = 60.25-97.35; median after sealing = 0.00; 25th-75th = 0.00-77.08; p = 0.001). L. paracasei was the most prevalent species of lactobacilli in carious dentin (p = 0.02). L. rhamnosus prevalence increased to a proportion similar to L. paracasei after CS (p = 0.001). A total of 28 and 14 different genotypes were found before and after CS, respectively. There was no difference between the L. paracasei and the L. rhamnosus isolated from carious dentin, neither regarding acid production nor acid tolerance. CONCLUSIONS: Although there was a significant reduction in lactobacilli in the residual carious dentin after SCR, some strains were capable of surviving after three months of CS. However, the sealed available nutrients are low and not sufficient for caries progression. Also, we believe that a longer follow up period may eliminate all the residual lactobacilli. L. paracasei prevailed in carious dentin in a proportion similar to L. rhamnosus in the sealed dentin. Characterization of lactobacilli after SCR and sealing may help the understanding the importance of genotyping of lactobacilli in carious microbiota.

Microbial Load After Selective and Complete Caries Removal in Permanent Molars: a Randomized Clinical Trial.

The aim of this randomized clinical trial was to compare the remaining microbial load after treatments based on complete and selective caries removal and sealing. Patients with active carious lesions in a permanent molar were randomly allocated into 2 groups: a test group (selective caries removal-SCR; n=18) and a control group (complete caries removal - CCR; n=18). Dentin samples were collected following the excavation and three months after sealing. Streptococcus species, Streptococcus mutans, Lactobacillus species, and total viable microorganisms were cultured to count the viable cells and frequency of species isolation. CCR resulted in significant lower total viable microorganisms counts (p≤0.001), Streptococcus species (p≤0.001) and Lactobacillus species (p≤0.001) initially. However, after sealing, a decrease in total viable microorganisms, Streptococcus species, and Lactobacillus species in the SCR resulted in no difference between the groups after 3 months. In conclusion, selective caries removal is as effective as complete caries removal in reducing dentin bacterial load 3 months after sealing.

Microbial load after selective and complete caries removal in permanent molars: a randomized clinical trial

Abstract The aim of this randomized clinical trial was to compare the remaining microbial load after treatments based on complete and selective caries removal and sealing. Patients with active carious lesions in a permanent molar were randomly allocated into 2 groups: a test group (selective caries removal-SCR; n=18) and a control group (complete caries removal - CCR; n=18). Dentin samples were collected following the excavation and three months after sealing. Streptococcus species, Streptococcus mutans, Lactobacillus species, and total viable microorganisms were cultured to count the viable cells and frequency of species isolation. CCR resulted in significant lower total viable microorganisms counts (p≤0.001), Streptococcus species (p≤0.001) and Lactobacillus species (p≤0.001) initially. However, after sealing, a decrease in total viable microorganisms, Streptococcus species, and Lactobacillus species in the SCR resulted in no difference between the groups after 3 months. In conclusion, selective caries removal is as effective as complete caries removal in reducing dentin bacterial load 3 months after sealing.

Resumo O objetivo deste ensaio clínico randomizado foi comparar os microrganismos remanescentes após tratamentos baseados em remoção total de tecido cariado e selamento e a remoção seletiva de tecido cariado e selamento. Pacientes com lesões de cárie ativas em molares permanentes foram divididos aleatoriamente em dois grupos: grupo teste (remoção seletiva de tecido cariado-SCR; n=18), e grupo de controle (remoção total de tecido cariado-CCR; n=18). Amostras de dentina foram obtidas após a remoção da tecido cariado e após 3 meses de selamento das cavidades. Streptococcus spp., Streptococcus mutans, Lactobacillus spp. e microrganismos viáveis totais foram cultivados para contagem de células e frequência de isolamento de espécies. CCR resultou em menores contagens totais de microorganismos viáveis (p≤0,001), Streptococcus spp. (p≤0,001) e Lactobacillus spp. (p≤0,001) inicialmente. Entretanto, após o selamento, uma redução significativa nas contagens totais de microrganismos viáveis, Streptococcus spp. e Lactobacillus spp. resultou em nenhuma diferença entre os grupos após 3 meses. Conclui-se que a remoção seletiva de cárie é tão seletiva quanto a remoção completa de cárie na redução da infecção dentinária após três meses com selamento da lesão.