Antibacterial effects of chemomechanical instrumentation and calcium hydroxide in primary teeth with pulp necrosis.

Purpose: This study's purposes were to: evaluate the antibacterial effect of chemomechanical instrumentation and a calcium hydroxide-based dressing in primary teeth with pulp necrosis secondary to trauma; and detect the presence of Fusobacterium nucleatum and black-pigmented rods in the canals of these teeth.

Methods: Microbiological sample collections (MSCs) were obtained: after coronal access to the canals of primary incisors (in 18 teeth; MSC 1); after chemomechanical instrumentation (in 10 teeth; MSC 2); and 72 hours after removal of intracanal medication (in 18 teeth; MSC 3). These samples were sent for microbiological processing. The results were analyzed statistically via chi-square, analysis of variance, and Games-Howell tests (P<.05).

Results: Micro-organisms were isolated in approximately 94%, 10%, and 83% of canals, respectively, in MSCs 1, 2, and 3. There was a statistically significant difference only between MSCs 1 and 2 (P<.03). F nucleatum and black-pigmented rods were detected in approximately 56% and 11% of canals in MSC 1, respectively.

Conclusion: Chemomechanical instrumentation and calcium hydroxide-based dressing have an anti-bacterial effect by significantly reducing the number of micro-organisms in the main root canal. They showed a limited efficacy, however, and did not prevent bacterial regrowth after endodontic therapy in primary teeth with pulp necrosis secondary to trauma.