Microbial Contamination of 19 Consumable Dental Materials: An In Vitro Study

Introduction: Increase in the incidence of contagious diseases emphasizes the importance of microbial contamination of dental materials. The purpose of this in vitro study was to determine microbial contamination of different consumable dental materials for the presence of viable microorganisms. Materials & Methods: In this study, 19 consumable dental materials were surveyed for microbial contamination. These materials included: three kinds of gutta percha, paper cones, gingival retraction cords, alginates, wooden wedges, two kinds of prophylaxis pastes, and one kind of dental dressing and zinc oxide powder. From each material, three brands and from each brand three samples were obtained. Solid and liquid specimens were cultured on Tryptic Soy Broth, Thioglycolate and Sabouraud Dextrose Agar and all of the cultured media were stained by gram method. Data were analyzed by SPSS-16 software using descriptive and analytical (Fisher's exact and Chi-Square) tests. The level of significance was set at 0.05.. Results: Both prophylaxis pastes, one kind of dental dressing and zinc oxide powder, two of alginates, two of wooden wedges and one of retraction cords did not have any bacterial contamination. The most common bacteria in the contaminated materials were anaerobic Gram-positive bacilli (18 cases, 32%), aerobic Gram-positive bacilli (17 cases, 30.4%), aerobic Gram-negative bacilli (14 cases, 25%), aerobic Gram-positive cocci (three cases, 5.4%), anaerobic Gram-negative bacilli (two cases, 3.6%) and anaerobic Gram-positive cocci (two cases, 3.6%). Conclusion: Approximately, 47 percent of tested dental materials did not have any microbial contamination. The bacilli were the most common bacteria in contaminated materials. Although these microbes may not be pathogenic in ordinary conditions, they can represent a risk for immunocompromised patients.