Longitudinal study of dental caries incidence associated with Streptococcus mutans and Streptococcus sobrinus in pre-school children

Abstract

Streptococcus mutans and Streptococcus sobrinus are known to be associated with the development of dental caries. In this study these bacteria were detected in pre-school children (each with primary dentition, age range 3-5 years, n ¼ 60) using a PCR method, and then their presence was compared with the incidence of dental caries over a 1-year period. Plaque samples were collected from all erupted tooth sites using a sterile toothbrush. Dental examinations at the beginning of the study (baseline) and after 1 year were also performed to determine decayed, missing, filled teeth (dmft) scores using WHO caries diagnostic criteria. The prevalences of S. mutans and S. sobrinus across all the subjects were 61 . 7 % and 56 . 6 %, respectively; 13 subjects (21 . 7 %) were positive for S. mutans alone, 10 (16 . 6 %) were positive for S. sobrinus alone and 24 (40 . 0 %) were positive for both S. mutans and S. sobrinus, whereas 13 (21 . 7 %) were negative for both S. mutans and S. sobrinus. dmft scores of subjects positive for both S. mutans and S. sobrinus at baseline and after 1 year were significantly higher than of those positive for S. mutans alone at the same stages (P , 0 . 01 and P , 0 . 001, respectively). The caries incremental increase was also significantly greater in those with both bacteria detected (P , 0 . 05). Our results indicate that pre-school children harbouring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone. INTRODUCTIONMutans streptococci (Streptococcus mutans and Streptococcus sobrinus) are considered to be major dental caries aetiologic agents. They are the most common pathogens isolated from human dental plaque and their prevalence has been reported in epidemiological studies (Hamada & Slade, 1980;Whiley & Beighton, 1998). S. mutans has been shown to be more prevalent than S. sobrinus in dental plaque samples (Loesche, 1986; Carlsson et al., 1987), while several epidemiological studies have shown that the prevalence of S. sobrinus is more closely associated with high caries activity (Fujiwara et al., 1991;Hirose et al., 1993).In several epidemiological studies, identification of S. mutans and S. sobrinus on selective media such as mitis-salivarius (MS) or MS-bacitracin (MSB) agar has been performed using colonial morphology (Wade et al., 1986;Svanberg & Krasse, 1990). However, accurate differentiation between S. mutans and S. sobrinus is not easy, and is also timeconsuming and laborious (de Soet et al., 1990). Further, it has been reported that S. sobrinus from dental plaque samples is especially difficult to culture directly on MSB selective medium (Jordan 1986;de Soet et al., 1990). Thus, it is of great importance to distinguish the presence of these two species separately in children for accurate prediction and effective prevention of dental caries.Thus far, several methods used for detecting and identifying mutans streptococci have been reported, including direct microscopy, cultivation, enzyme tests, mAbs, ELISAs and specie...

Detection of streptococcus mutans and streptococcus sobrinus in dental plaque samples from Brazilian preschool children by polymerase chain reaction

“…However, the outcomes of the present study were quite different from those of Okada et al (16), who reported 72.8% and 61.1% for S. mutans and S. sobrinus in 3-5 years old Japanese preschool children. In another study, Okada et al (17) found prevalences of 61.7% and 56.6% for S. mutans and S. sobrinus, respectively, in Japanese children. In both studies (16,17) the authors reinforced the statement that children who harbor both bacteria together have a significantly higher caries incidence and incremented increase, compared to those with S. mutans alone.…”

“…In another study, Okada et al (17) found prevalences of 61.7% and 56.6% for S. mutans and S. sobrinus, respectively, in Japanese children. In both studies (16,17) the authors reinforced the statement that children who harbor both bacteria together have a significantly higher caries incidence and incremented increase, compared to those with S. mutans alone. In the present study, it was no detected the presence of both species together in any dental plaque sample from Brazilian children.…”

“…Several studies have reported that children harboring both S. mutans and S. sobrinus had a significantly higher caries incidence than those with either S. mutans or S. sobrinus alone (16,17,19). Recently, a hypothesis stating that mixed colonization by both S. mutans and S. sobrinus is an important factor for the development of caries has been reported (20).…”

“…In the present study, there were several cases of caries-free children who had S. mutans or S. sobrinus alone (n=19, Table 3). In a recent study (17), 13 out of 77 (16.9%) children were shown to be caries-free. Even though, 7 (53.8%) of them presented either S. mutans or S. sobrinus alone, in agreement with the present results.…”

Association of oral streptococci community dynamics with severe early childhood caries as assessed by PCR-denaturing gradient gel electrophoresis targeting the rnpB gene

“…However, due to the complex interspecies interactions, there is also evidence to suggest that other species of oral streptococci may have different roles in the caries process (Kanasi et al, 2010). Most previous studies on the microbial risk indicators for dental caries have focused mainly on one or several possible pathogens Ge et al, 2008;Okada et al, 2005). Studies that have investigated dental plaque from a microbial ecological perspective are rare.…”