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...

Streptococcus mutans and S. sobrinus are associated with the development of dental caries. These bacteria were detected by PCR and then their presence was compared with the incidence of dental caries in 77 Japanese pre-school children. Plaque samples were collected from all erupted tooth sites in the subjects, aged 3-5 years old and each with primary dentition, with a sterile toothbrush. A dental examination was performed for dmft (decayed, missing, filled, total) with the WHO caries diagnostic criteria. In all subjects, the prevalence of S. mutans and S. sobrinus was 72.8% and 61.1%, respectively; 19 (24.7%) were positive for S. mutans alone, 10 (13.0%) were positive for S. sobrinus alone, 37 (48.1%) were positive for both S. mutans and S. sobrinus, and 11 (14.3%) were negative for both S. mutans and S. sobrinus. The dmft scores of children positive for both S. mutans and S. sobrinus were significantly higher than those positive for S. mutans alone. These results indicate that children harbouring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.

The purpose of this study was to detect the presence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in plaque samples from 104 children, collected from their toothbrushes using a polymerase chain reaction (PCR). The age range of all subjects was 2-12 years. 21, 73 and 10 children with healthy gingiva, gingivitis and periodontitis respectively were selected. Plaque samples were collected from all erupted teeth sites using a sterile toothbrush. The mean concentration of DNA recovered from brushing plaque samples was approximately 660 microg/ml, which was sufficient for performing a PCR-based survey. Both A. actinomycetemcomitans and P. gingivalis were detected in the primary and mixed dentition. The prevalence of A. actinomycetemcomitans in healthy subjects was 4.8%, and those with gingivitis and periodontitis was 6.8% and 20.0% respectively, while the prevalence of P. gingivalis was 4.8% in healthy subjects, and 9.6% and 20.0% in those with gingivitis and periodontitis, respectively. Our survey, using a toothbrush, indicated that A. actinomycetemcomitans and P. gingivalis are rarely present in oral cavities of healthy children.

Our survey indicated that P. intermedia and T. denticola were more associated with periodontal diseases, B. forsythus and P. nigrescens had a moderate prevalence in all clinical groups, while C. rectus were the most commonly detected species in the oral cavities of children suggesting establishment in their early years.

BackgroundMutans streptococci (Streptococcus mutans and S. sobrinus) are considered to be major etiologic agents of dental caries. Using a polymerase chain reaction method, we detected those bacteria from 145 outpatients (6–30 years old) with intellectual disabilities (ID) and their presence was compared with the incidence of dental caries.MethodsPlaque samples were collected from all erupted tooth sites in subjects with a sterile toothbrush. A dental examination was performed to determine the number of decayed and filled teeth (DFT score) in permanent dentition using the WHO caries diagnostic criteria. A Mann–Whitney U-test was employed to compare the caries scores between combinations of the bacteria, and with a Wilcoxon rank test used to compare caries scores between the baseline and after 1 year.ResultsAmong all subjects, S. mutans and S. sobrinus were possessed by 78.7 and 83.5 %, respectively, while 13.1 % were positive for S. mutans alone, 17.9 % for S. sobrinus alone, and 65.6 % for both organisms, with 3.4 % were negative for both. The mean DFT score of subjects positive for both S. mutans and S. sobrinus at after 1 year was significantly higher than that of those positive for S. mutans alone (P < 0.01). The increase in caries increment was also significantly greater in subjects with both bacteria detected (P < 0.001).ConclusionOur results indicate that patients with ID harboring both S. mutans and S. sobrinus have a significantly higher incidence of dental caries than those with S. mutans alone.