Type IV Dental Stone Incorporated with Antimicrobial Agents and its Physical Properties

Abstract

Contamination of dental casts can occur via direct contact with impression materials that are contaminated by patients fluids. Thus, the development of dental stone with antimicrobial activity to reduce cross-contamination between patients and laboratory personnel is needed. This study aims to evaluate the influence of incorporation of disinfectants into type IV dental stone on its antimicrobial activities and physical properties such as setting time and dry compressive strength. Type IV dental stone incorporated with 4 types of disinfectants; Diamond Rock D (3-iodo-2-propynylbutylcarbamate), Diamond Rock B (zeolite), Diamond Rock Z (thiabendazole) and Diamond Rock T (2-benzimidazole carbamic acid), were tested in this study compared with the control, Diamond Rock O (type IV dental stone without disinfectant). Microorganisms tested wereStaphylococcus aureusATCC 6538,Pseudomonas aeruginosaATCC 27853 andCandida albicansATCC 1023. One hundred μL of each microbial suspension (108CFU/mL) was dropped on hydrocolloid impression (Jeltrate; Caulk/Dentsply, Milford, DE) and left dry. All types of stone mixes were prepared and poured into the impressions and allowed to set for 60 min. Then the stone samples were removed and the microbial contact surfaces were imprinted on Brain Heart Infusion agar plates. After incubation, colonies appeared on agar were gram-stained and counted. The setting time and dry compressive strength were tested in accordance with International Standard (ISO) 6873: 1998 (E). Dental stone incorporated with 4 types of disinfectants showed antimicrobial activity against all tested microorganisms with the percentage of microbial reduction ranging from 83% to 100%. Among all types of dental stone, no significant difference in setting time was observed. In dry compressive strength testing, the disinfectant-containing dental stone had significant higher strength than that without the disinfectant. The newly developed type IV dental stone incorporated with disinfectants had antimicrobial effects against all tested microorganisms. The physical properties of the modified dental stones were within the ISO standards. However, further investigation on other properties such as dimensional stability, detail reproduction and clinical usage are still needed.