IN VITRO ADHERENCE OF STREPTOCOCCUS MUTANS TO THE SURFACE OF METALLIC AND POLYCARBONATE ORTHODONTIC BRACKETS

Abstract

Objective: to verify Streptococcus mutans (ATCC 25175) adherence to the surface of two types of orthodontic brackets. Material and Methods: Three metal and three polycarbonate brackets were used and testes according to the following groups: G1 (2 mL of BHI broth plus 140 µL of inoculum), G2 (2 mL of BHI broth containing sucrose plus 140 µL of inoculum) and G3 (2 mL of BHI broth - sterility control). A bracket of each type was immersed in each solution (G1, G2 or G3). All solutions were incubated at 37°C/24h, microaerophilic. Then, each bracket was transferred to a test-tube containing 2 mL of sterile saline solution, which underwent serial dilutions. Aliquots of 0.02 mL from each dilution were inoculated in triplicate on Petri-plates containing MSB culture medium through drop technique. Plates were incubated at 37ºC, microaerophilics. After 48h, it was performed the CFU/mL counting. Results: CFU/mL means for the brackets immersed in G1 were 6.3x102 (metal) and 1x102 (polycarbonate). For G2, the means were 5.6x105 (metal) and 2.4x105 (polycarbonate). Difference was found for the number of CFU/mL adhered to the surfaces of brackets incubated in G1. Nevertheless, no difference was verified for the group incubated in G2. Conclusion: It is estimated that there are differences between metal and polycarbonate brackets’ surfaces. Presence of sucrose enhanced adherence of microorganisms to the surfaces evaluated. DESCRIPTORS: Bacterial Adhesion. Biofilms. Orthodontic Brackets.