Objective: To evaluate
in vitro the effectiveness of Sodium Hypochlorite (liquid), Sodium Hypochlorite (gel), Chlorhexidine and Doxycycline as irrigants applied with different application methods on micro-organisms within root canals. Methods: Root canals of 50 single-rooted teeth were prepared with Protaper files. The teeth were sterilized and divided into two groups. One group was inoculated with a 1% MacFarland Standard 1 suspension of
Enterococcus faecalis (ATCC 49474) and the other with
Actinobacillis actinomycetamcomitans (ATCC 33384) in BHI broth and incubated for 72 hours. The teeth were divided into 10 groups, 5 teeth in each group. Group 1 Sodium Hypochlorite 3,5% (liquid), Group 2 Sodium Hypochlorite 2 % (gel), Group 3 Chlorhexidine Gluconate 2,5%, Group 4 Doxycycline-HCl 100mg/2ml and Group 5 Control Group, distilled water. After irrigating with each of the solutions using different irrigating methods, microbial samples were collected and bacterial growth was determined. The teeth were fractured; samples were fixated and prepared according to the standard method of Bullock and Petrusz (1985) for scanning electron microscopy (SEM). After drying and gold spatter coating, samples were viewed and analyzed in a JOEL JSM-840 SEM. Results: Microbiological cultivation indicated that 2,5% Chlorhexidine gluconate and Doxycycline-HCl were effective in eliminating both micro-organisms from the root canal. The most effective irrigating method was the rotary brush. SEM images confirmed these results. Conclusion: This study highlighted the importance of the methods of introducing the irrigant into the root canal. Irrigants introduced with a syringe into the root canal had little or no effect on the smear layer. If the same irrigant was introduced with a sonic scaler or rotary brush, the smear layer was removed and micro-organisms were eliminated.