Evaluation of Gram's method of staining for the prognosis of root canal treatment in nonvital dental pulps.

An evaluation of Gram's method of staining of 601 nonvital dental pulps was performed. It gave positive results in 60.1% of the cases, the most frequent finding was gram-positive cocci. Preoperative x-ray status correlated significantly with the staining results but the size of the radiolucency did not. Previously treated teeth gave less positive staining results than other teeth. There was an obvious correlation between presence of bacteria and various complications (p < 0.001), but no differences were noted between the combinations of bacteria. The teeth that were the most resistant to complications seemed to be the lower canines. The staining results did not correlate with sex, systemic diseases, or preoperative symptoms. We believe that Gram's method of staining is a useful, rapid aid in root canal therapy, especially in complicated cases.