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Objectives: Streptococcusmutans has significant virulence factors associated with the etiologyand pathophysiology of dental plaque and caries through adherence to the tooth surface and biofilm formation.The purpose of this study was to investigate correlation between biofilm formation and glucan-binding proteins in Streptococcus mutans bacteria isolated from dental caries.
Methods and Materials: Selective cultivationon mitis-salivarius-bacitracin (MSB) agar, biochemical tests and VITEK 2 system were carried out to isolate and identify S. mutans bacteria from 100 patients with dental caries. The identification was confirmed by PCR assay using specific pairs of PCR primers targeting the S. mutansSm479 gene.Biofilm formation by S. mutans isolates was estimated using the microtiter plate crystal violet method.PCR also were carried out to detect genes encoding bacterial adhesion (gbpA, gbpB, and spaP) and biofilm formation (relA).
Results: A total of 42 S. mutans isolates were recovered from 100 clinical samples collected in the current study. There was a statistically significant difference in the biofilm formation ability among the isolates of S. mutans based (p < 0.01).Percentages of biofilm formation were 14.28% (6/42) strong biofilm producer, 35.71% (15/42) moderate biofilm producer, 28.57% (12/42) weak biofilm producer and 21.42% (9/42) non biofilm producer. Molecular detection of gbpA, gbpB, spaP and relA genes was done for all S. mutans. The results showed that 80.95% (34/42), 85.71% (36/42), 66.66% (28/42) and 76.19% (32/42) of samples gave positive results for gbpA, gbpB, spaP and relA genes,respectively. The gbpA gene encodesglucan-binding protein (Gbp)A, the gbpB gene encodes GbpB, and the spaP gene encodes cell surface antigen, SpaP.The relA gene contribute to quorum-sensing and biofilm formation.