The relationship of Bacteroides melaninogenicus to symptoms associated with pulpal necrosis.

The canal contents of thirty-three cariously and traumatically exposed pulpless teeth were sampled with a special technique and cultured anaerobically for growth in prereduced thioglycollate and for Bacteroides melaninogenicus on selective blood agar plates. The presence of B. melaninogenicus was compared with the presence or absence of eight symptoms associated with pulpal necrosis and the presence or absence of growth in thioglycollate. B. melaninogenicus was found to be significantly related to pain, sinus tract formation and foul odor. Suggested relationships were found between the organism and the presence of apical sensitivity and local swelling. Growth in prereduced thioglycollate occurred more often from teeth in which B. melaninogenicus was present. With the sampling technique used, positive growth in the thioiglycollte ranged from 88 percent at the initial appointment to 72 percent at the fill appointment.