Identification of Mutans Streptococci isolated from dental plaque between the bracket and tooth surface in orthodontic patients

Kim, Mi Ae; Yoo, So Young; Kim, Hwa Sook; Kook, Joong Ki; Lim, Sung Hoon; Yoon, Young Jooh; Kim, Kwang Won

Abstract

The aim of this study was to compare the species and biotypes of mutans streptococci isolated from dental plaques sampled from the interfaces between the bracket and tooth surface and smooth tooth surfaces in orthodontic patients. Dental plaque was collected from the interfaces between brackets and teeth (test group), and from smooth tooth surfaces distant from brackets by more than 2 mm (control group). The dental plaque collected by a sterilized curette was transferred into a vial of 1 X PBS. The sample in the vial was vigorously vortexed for 1 min and plated on mitis-salivarius bacitracin (MSB) agar plate using cotton tips. The agar plates were incubated at 37 degrees C in a candle jar for 2 days, and again incubated for 1 more day at anambient temperature. Individual colonies were cultured in TH broth at 37 degrees C CO2 incubator. The PCR-RFLP based on dextranase gene was performed for the identification of mutans streptococci at the species-level. For biotyping of mutans streptococci, biochemical tests were performed. There was no significant difference of the species of mutans streptococci isolated from both test and control groups. However, the biotypes of the mutans streptococci isolated from test and control groups were different. These results may offer the basic data to verify the relationship between the mutans streptococci biotype and enamel decalcification or dental caries in orthodontic patients with fixed appliances.