Comparative Molecular Analysis of Gram-Negative Bacteria in Primary Teeth with Irreversible Pulpitis or Periapical Pathology.

Purpose: The purpose of this study was to compare the Gram-negative pathogens identified in the root canals of primary teeth with irreversible inflammatory pulpitis and in teeth showing apical periodontitis. Methods: Samples were collected from 123 root canals of primary teeth from three- to seven-year-old patients. Root canals were assigned to either group one (irreversible inflammatory pulpitis; <small>n</small> equals 63) or group two (pulp necrosis and apical periodontitis; n equals 60). Total number of cells of selected Gram-negative microorganisms was determined by the checkerboard DNA-DNA hybridization technique. Demographic data were compared using either chi-squared or t tests. Total numbers of microorganisms were compared using the Mann-Whitney test ( α equals 0.05). Results: There were no significant intergroup differences in gender, age, and tooth group distribution (P>0.05). Among the 123 samples, 17 were discarded due to salivary contamination. The total numbers of Prevotella nigrescens, Treponema denticola, Fusobacterium nucleatum polymorphum, Fusobacterium nucleatum spp nucleatum, Aggregatibacter actinomycetemcomitans serotype a, Aggregatibacter actinomycetemcomitans serotype b, Porphyromonas gingivalis, Prevotella intermedia, and Prevotella melaninogenica were higher in teeth with apical periodontitis compared to those with irreversible inflammatory pulpitis (P<0.05). Conclusion: Higher numbers of Gram-negative bacteria were found in teeth with apical periodontitis compared to teeth with irreversible in- flammatory pulpitis.