Genotypic diversity and acidogenicity of Streptococcus mutans in Down syndrome children

The Incidence of Dental Caries in Children with Down Syndrome: A Systematic Review and Meta-Analysis

Scientific evidence regarding the incidence of dental caries in Down syndrome (DS) patients is limited and sometimes presents divergent opinions among authors, making it difficult to reach definitive conclusions. We aimed to evaluate the caries incidence in the DS pediatric population and compare it against healthy controls. The search was performed using 4 universal databases: Cochrane, B-on, Biomed, and PubMed. The selected articles were synthesized and subsequently evaluated according to an adaptation of the Quality Assessment Checklist for Prevalence Studies risk of bias tool, and analysis charts were performed by the Risk of Bias visualization tool (ROBVIS). Statistics and graphs were performed by Open Meta Analyst and JASP software. The confounding effect on caries incidence of the following factors was evaluated through meta-regression: age, Male/Female (M/F) ratio, DMFT, dmft, and study geographic location. Overall, the incidence of caries in the DS population was 49.9%, whereas in the control population was 63.4%. The M/F ratio, DMFT, and dmft significantly affected the incidence of DS individuals (p-value < 0.05). The evidence regarding the lower pooled incidence of caries in individuals with DS regarding controls is limited by the few scientific reports available and cross-section designs. Therefore, further studies are needed to confirm these results.

Phenotypic and Genotypic Characterization of Streptococcus mutans Strains Isolated from Endodontic Infections

Streptococcus mutans plays an important role in caries etiology and eventually in systemic infections. However, it is often found in infected root canals, but the pathophysiological characteristics of strains residing in this site are largely unknown. Here, we characterized strains of S. mutans isolated from root canals of primary (PI) and secondary/persistent (SI) endodontic infections in relation to serotype and genotype; presence of genes coding for collagen binding proteins (CBPs); collagen binding activity and biofilm formation capacity; ability to withstand environmental stresses; systemic virulence in Galleria mellonella; and invasion of human coronary artery endothelial cells and human dental pupal fibroblasts. Samples from 10 patients with PI and 10 patients with SI were collected, and a total of 14 S. mutans isolates, belonging to 3 genotypes, were obtained. Of these, 13 were serotype c, and 1 was serotype k. When compared with the reference strains, the clinical isolates were hypersensitive to hydrogen peroxide. Remarkably, all 14 strains harbored and expressed the CBP-encoding gene cbm, showing increased binding to collagen, enhanced systemic virulence in G. mellonella, and ability to invade human coronary artery endothelial cells and human dental pupal fibroblasts when compared with CBP-negative strains. Whole genome sequence analysis of PI and SI isolates revealed that these strains are phylogenetically related but genetically distinct from each other. Our findings highlight the importance of CBPs in facilitating colonization and persistence of S. mutans in collagenous substrates such as root canals and their potential role in the pathogenesis of endodontic infections.