Classification of a patient's caries activity based on lesion activity assessment among adults: findings from a prospective cohort study.

OBJECTIVE: To investigate whether the classification of a patient's caries activity based on lesion activity assessment can predict the increment and progression of coronal and root caries lesions among adults. METHODS: This population-based prospective cohort study followed 413 individuals (mean age 54.1) from southern Brazil for 4 years. Data collection included a questionnaire and clinical examination to record coronal/root caries and gingival recession. The main outcomes were caries increment measured as decayed, missing and filled tooth surfaces (DMFS) and caries progression (surface-level analysis). The main predictor variable was patients' caries activity at baseline ("caries-inactive" or "caries-active"). Negative binomial regression models (unadjusted and adjusted) were used. RESULTS: Caries-active individuals were more likely to present DMFS increment than caries-inactive ones when migrations among DMFS components were considered (IRR [incidence risk ratio] = 1.26, 95%CI [confidence interval] = 1.01-1.58). On the other hand, no such association was found when these migrations were disregarded. The risk for coronal caries progression on filled surfaces was 90% higher among caries-active patients (IRR=1.9; 95%CI=1.4-2.6). In addition, patient's caries activity was able to predict higher risk for root caries progression in newly exposed root surfaces (IRR=1.9; 95%CI=1.0-3.6). CONCLUSION: The classification of a patient's caries activity based on lesion activity was able to foresee lesion progression on the coronal and root surfaces more susceptible to caries among adults. Clinical relevance Classifying a patient's caries activity is a useful tool for the clinical management of dental caries in adults.

The effect of coconut sugar on cariogenic traits in Streptococcus mutans / Efeito do Açúcar de Coco na cariogenicidade do Streptococcus mutans

Aim: The consumption of foods rich in sugar is linked to several non-communicable diseases, including dental caries. Coconut sugar has systemic benefits due to its lower glycemic indexes (GI) than other table sugars. However, there is currently no data regarding its ca-riogenic potential. This study aimed to evaluate the effect of coconut sugar on acidogenicity and adhesion of Streptococcus mutans in vitro, compared to sugarcane products. Materials and methods: Aliquots of cultu-res of S. mutans UA159 were resuspended in a buffer solution enriched with coconut sugar, crystal sugar (refined sugar), and minimally processed sugarcane (demerara light brown sugar and maskavo dark brown sugar), as well as positive (sucrose) and negative con-trols. The decrease in pH and its corresponding area under the curve (AUC; cm2) were evaluated for the analysis of acidogenicity. S.mutans was incubated in BHI supplemented with each sugar and the percentages of microbial adhesion were calculated. After testing data normality, the one-way ANOVA test (Bonferroni post hoc) was used to compare the AUC and the pro-portion of adhesion of each group. Results: Regarding the acidogenic potential, statistical differences were found only between the negative control versus all other groups (p<0.001). Likewise, no significant difference in adhesion was found between the tested sugars (p>0.05). Discussion: Although the tested sugars are marketed as "healthy products," their amount and frequency of usage should be controlled. Conclusion: Coconut su-gar presents a similar cariogenic potential to that of sugarcane products when acidogenicity and adhesion are evaluated. Coconut sugar is not indicated as a substitute for sucrose in the control of cariogenic activity.

Objetivo: O consumo de alimentos ricos em açúcar está associado a diversas doenças não transmissíveis, incluindo a doença cárie. O açúcar de coco tem benefícios sistêmi-cos devido aos seus índices glicêmicos (IG) mais baixos do que outros açúcares de mesa. No entanto, atualmente não há dados sobre seu potencial cariogênico. Esse estu-do teve como objetivo avaliar o efeito do açúcar do coco na acidogenicidade e adesão de Streptococcus mutans in vitro, em comparação com produtos derivados da cana--de-açúcar. Materiais e métodos: alíquotas de culturas de S. mutans UA159 foram suspensas em solução tampão enriquecida com açúcar de coco, açúcar cristal (açúcar refinado) e cana-de-açúcar minimamente processada (açúcar mascavo demerara claro e açúcar mascavo), além de controles positivo (sacarose) e negativo. A diminuição do pH e correspondente área sob a curva (AUC; cm2) fo-ram avaliadas na análise de acidogenicidade. S. mutansfoi incubado em BHI suplementado com cada tipo de açúcar e as porcentagens de adesão microbiana foram calculadas. Após testar a normalidade dos dados, o teste ANOVA de uma via (Bonferroni post hoc) foi utilizado para comparar a AUC e a proporção de adesão de cada grupo. Resultados: Em relação ao potencial acidogênico, diferenças estatísticas foram encontradas apenas entre o controle negativo versus todos os outros grupos (p <0,001). Não foi encontrada diferença significativa na adesão en-tre os açúcares testados (p> 0,05). Discussão: Apesar dos açúcares testados serem comercializados como "produtos saudáveis", sua quantidade e frequência de consumo deve ser controlada. Conclusão: O açúcar do coco apresenta potencial cariogênico semelhante à dos produtos da cana-de-açúcar quanto a acidogenicidade e a adesão. O açúcar de coco não é indicado como substituto da sacarose no controle da atividade cariogênica.

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.

Gene expression of bacterial collagenolytic proteases in root caries.

Objective: It is unknown whether bacteria play a role in the collagen matrix degradation that occurs during caries progression. Our aim was to characterize the expression level of genes involved in bacterial collagenolytic proteases in root biofilms with and without caries. Method: we collected samples from active cavitated root caries lesions (RC, n = 30) and from sound root surfaces (SRS, n = 10). Total microbial RNA was isolated and cDNA sequenced on the Illumina Hi-Seq2500. Reads were mapped to 162 oral bacterial reference genomes. Genes encoding putative bacterial collagenolytic proteases were identified. Normalization and differential expression analysis was performed on all metatranscriptomes (FDR<10-3). Result: Genes encoding collagenases were identified in 113 bacterial species the majority were peptidase U32. In RC, Streptococcus mutans and Veillonella parvula expressed the most collagenases. Organisms that overexpressed collagenolytic protease genes in RC (Log2FoldChange>8) but none in SRS were Pseudoramibacter alactolyticus [HMPREF0721_RS02020; HMPREF0721_RS04640], Scardovia inopinata [SCIP_RS02440] and Olsenella uli DSM7084 [OLSU_RS02990]. Conclusion: Our findings suggest that the U32 proteases may be related to carious dentine. The contribution of a small number of species to dentine degradation should be further investigated. These proteases may have potential in future biotechnological and medical applications, serving as targets for the development of therapeutic agents.