Genotypes of Streptococcus mutans in saliva versus dental plaque

OBJECTIVE: The aim of this study was to investigate whether genotypes of Streptococcus mutans strain can be detected as effectively in saliva samples as in plaque samples from buccal surfaces and occlusal surface fissures of permanent first molars. DESIGN: The study included 20 school children aged 6-7 years who were positive for mutans streptococci. Samples of stimulated saliva and of dental plaque on buccal surfaces and occlusal surface fissures of permanent first molars were collected. Samples were cultivated in MSB agar. Up to nine isolates compatible with mutans streptococci were obtained and identified by means of biochemical tests. All isolates identified as S. mutans were genotyped by arbitrarily primed polymerase chain reaction. RESULTS: A total of 28 genotypes of S. mutans were isolated: 23 in saliva samples, 23 in buccal surface plaque samples, and 16 in plaque samples from occlusal surface fissures. CONCLUSIONS: Although, saliva sampling did not reveal all genotypes isolated, it was equally as effective as plaque sampling from the buccal surfaces of permanent first molars, and more effective than plaque sampling from fissures on their occlusal surfaces.