Microbiological contamination of normal saline solution used during endodontic treatment at different time intervals- An In vitro study

Aim: To examine possible microbiological contamination of normal saline solution under normal clinical surroundings, also to determine the duration for which dentist could use their normal saline solution without microbiological contamination using different techniques and to identify common micro organisms that may contaminate such solutions. Materials and Methods: Three procedures for collecting samples of the normal saline from each of three sealed plastic bottles available in market were used comparable to procedure routinely followed in clinics. 1. The bottle 1 was cut with sterile B.P. blade and normal saline solution was taken into a disposable plastic glass. 2. Evacuate normal saline solution from bottle 2 using sterile syringe 3. Evacuate normal saline from bottle 3 using sterile syringe and solution was taken into sterile autoclave container with all aseptic precautions. Same procedure was followed for each of three normal saline bottles of brand two. Samples were collected at 0, 2, 4 hours of clinical work timings every day for three consecutive days. Every time immediately after collecting sample of saline, it was inoculated onto the blood agar and MacConkey agar. Plates are then incubated. After obtaining growth, gram staining was done to identify and categorize the bacteria. Results: On day 1 of study, growth starts to appear in disposable glass technique by the end of day i.e. at 4 hr interval sample which consisted of gram positive cocci. Growth in the case of sterile syringe method started to appear at 2 hrs on day 3 which was also gram positive cocci and in the case of sterile container growth started to appear at 4 hr sample on day 3, again gram positive cocci. Conclusions: The present study showed that microbiological contamination does occur whatever technique may be followed. Saline from sealed bottle should be used for once, then it should be discarded. However, amongst methods used in study, the best method that dentist could use is the use of sterile autoclaved container which can be best used maximum for two days using same bottle of saline. The use of disposable glass for keeping normal saline solution to be used root canal irrigation should be discarded. Also, this study indicated that most common contaminant in this solution was gram positive cocci.