Refractory periodontitis or recurrence of disease.

Refractory periodontal disease is characterized by low plaque scores and low responsiveness to periodontal therapy. The patients often have a history of antibiotic therapy and therefore have a high incidence of resistance in the subgingival microflora. The above features are in contrast to adult chronic periodontal disease and recurrence of disease. The subgingival microflora of refractory disease may be either predominantly gram-positive with elevated levels of Streptococcus intermedius or may be gram negative and contain elevated levels of the classical periodontal pathogens. In some cases serum IgG antibodies against Porphyromonas gingivalis are elevated and seem to decrease after therapy. Smoking may be an important factor in refractory periodontal disease. Treatment with directed antibiotic therapy as an adjunct to scaling and root planing retards the progression of disease for a limited time. Many questions are still not answered and suggestions are made for future directions in research.