Análise da bioadesão in vitro do streptococcus mutans sobre a superfície do aço inoxidável 316l de fios ortodônticos

Abstract

Orthodontic appliances, through its accessories, act as additional retainers of microorganisms potentially capable of forming biofilm. This study aimed to verify the in vitro adherence of Streptococcus mutans (ATCC 25175) to the metal surface of orthodontic wires. The sample comprised 90 orthodontic wires , and of these , 30 were allocated to the cell viability analysis using count colony forming units per microliter, 30 other wires were analyzed for adherence in scanning electron microscopy and 30 wires remaining were tested when the sterility of the experiment . The sample was divided into three sequences according to the type of solution in which the orthodontic wires were submerged in the sequence A, containing 9 ml of broth, brain heart infusion, and 1 ml of the bacterial inoculum, as in the sequence B, containing 9 ml of broth and brain heart infusion supplemented with 15% sucrose and inoculum 1mililitro and sequence control contained only 10 ml of broth and brain heart infusion. The orthodontic wires in these solutions were incubated at 37 ° C for 24 h in microaerophilic. Then each orthodontic wire were transferred to new tubes containing culture medium with 9 ml of broth and brain heart infusion and 1 ml of bacterial inoculum . This procedure was done for both sequences during the interval 24/24h within 10 days. Then each orthodontic wire was immersed in 1 ml of sterile saline and were stirred for 2 minutes and the resulting solution underwent serial dilutions. Aliquots of 25 microliters of each dilution were inoculated in triplicate in Petri dishes containing agar plates of brain heart infusion. The plates were incubated at 37 ° C / 48 h in microaerophilic conditions for counting colony forming units per milliliter by use of the technique of drop. For the analysis in scanning electron microscopy, the 30 wires were fixed and metallic, and then analyzed by scanning electron microscopy. There was a greater number of viable cells of S. mutans in the wire sacarosada incubated in the solution with respect to solution containing only brain heart infusion. In the analysis in scanning electron microscopy showed that the colonies had more grip in the solution when subjected sacarosada. We conclude that surfaces orthodontic wires are susceptible to colonization by S. mutans, and that the addition of sucrose in the culture medium increased bacterial adherence to the orthodontic wires