Year : 2015

Volume : Volume 5

Issue : Issue 2

Address for correspondence :
Dr. Sreeramulu B
drsreeramulub@gmail.com

Abstract

Aim: The aim of this study is to determine, whether saliva has a role in the contribution of bacterial growth on the surface of dental casts over a period of time and whether  disinfection  can minimize the bacterial growth of contaminated casts with saliva. Materials and Methods: 60 standardized dental stone cylinders were fabricated with master model dies of 24mm in length and 6mm in diameter. The specimens were divided into 5 groups of 12 each. The first group (control) of 12 specimens was  neither contaminated with saliva nor treated with disinfectant. The second group of 12 specimens was contaminated with 25 ml of saliva for 5 minutes and was  not treated with any of the disinfectants. The third group of 12 specimens was contaminated with 25 ml of saliva for 5 minutes and was rinsed with running tap water for 20 seconds. The fourth group of specimens was contaminated with 25 ml of saliva for 5 minutes and soaked in 5%  sodium hypochlorite for 20 seconds. The fifth group of 12 specimens was contaminated with 25 ml of saliva for 5 minutes and soaked in 2% glutaraldehyde for 20 seconds. The treated dental stone cylinders were placed in individual test tubes containing 2.5 ml of sterile phosphate buffer solution and a final dilution of 10-4 was achieved. These were transferred on the sheep blood agar plates which were inoculated and incubated at 370C for 24 hours. Results: Results demonstrated that all specimens contaminated with saliva and not disinfected had a large number of colony forming units (CFU) covering the blood agar plate. The specimens that were contaminated with saliva and rinsed only with water showed a diminished number of colony forming units. The specimens that were contaminated with saliva and soaked in 5% sodium hypochlorite had significantly less number of colony forming units when compared to that with only with tap water. All dental stone cylinders that were soaked for 20 seconds in 2% glutaraldehyde yielded no growth. The controls that were not contaminated with saliva had minimal growth on only few agar plates. The results of the ANOVA demonstrated that there was a significant difference between saliva-contaminated dental stone cylinders of group II and group V as compared to the other groups, indicating that soaking the dental stone cylinders in 5% sodium hypochlorite or soaking in 2% glutaraldehyde for 20 seconds had less chance of growth with micro-organisms.  Conclusion: Thus bacterial growth occurs on saliva contaminated dental casts, hence requires an effective method of disinfection.

Keywords: Dental stone, Disinfection, Sterilization, Colony forming units (CFUs).