Correlation Between Bacterial Type/bacterial Quantity and Bone Loss Detected by Cone Beam Computed Tomography (CBCT) in Primary Endodontic Infections.

Periapical lesions (PL) of endodontic origin are one of the most common pathological conditions that affect peri-radicular tissues. The main ob-jective of this study was to evaluate the amount and species of microorganisms isolated from necrotic pulps, establish a correlation between these and the size of periapical lesions, and how the amount and species of microorganisms decreased with non-surgical root canal treatment. Twenty-seven patients with a clinical diag-nosis of dental pulp necrosis and chronic periapical lesions were selected; a Cone Beam Computed Tomography (CBCT) and microbial samples of the root canal system were taken previous to a disinfection protocol, a post-instrumentation/disinfection protocol, and a post-medication placement. Samples were processed for colony-forming unit (CFU) counting, Gram staining technique, and bacterial identification by the API-20 Strep/API-20A system. The API system identified 21 species of microorganisms in the pre-instrumentation samples, 11 species in the post-instrumentation samples, and 11 in the post-medication samples. There was a correlation coefficient of 0.598% between the initial size of the lesion and the number of bacteria, with a coefficient of determination up to 35.7%, a correla-tion coefficient of 0.486% and a determination coefficient of 23.6% between the size of the periapical lesion and the number of CFUs. This study contributes to the knowledge of the amount and species of microorganisms isolated and identi-fied from necrotic pulps, establishes a correlation between the amount and spe-cies of microorganisms and the size of the periapical lesions, and shows how the decrease of microorganisms contributes to the healing of PL, corroborating the importance of an adequate disinfection protocol.