SERUM ANTIBODIES REACTING WITH SUBGINGIVAL SPECIES IN REFRACTORY PERIODONTITIS SUBJECTS

The purpose of this investigation was to compare the levels of serum I gG antibody to 85 subgingival species in 32 refractory periodontitis, 56 successfully treated, and 33 periodontally healthy subjects. Refrac tory subjects showed mean full mouth attachment loss and/or >3 sites s howing attachment loss >2.5 mm within 1 year after 2 treatment modalit ies, scaling and root planing and surgery plus systemically administer ed tetracycline. Successfully-treated subjects showed mean attachment level gain and no sites with attachment loss >2.5 mm, I year post-ther apy. Periodontally healthy subjects exhibited no pecker or attachment level >3 mm, and no evidence of progressing attachment loss during I y ear of monitoring. Baseline serum was obtained from each subject and r ested against 85 subgingival species, including reference strains and strains isolated from refractory subjects, using checkerboard immunobl otting. Significance of differences in levels of serum antibody among groups were sought using the Kruskal-Wallis test. Refractory subjects constituted a heterogeneous group based on their serum antibody respon se to subgingival species. Some individuals had antibody reactions to many subgingival species, while other subjects showed fewer or low num bers of responses. On average, refractory subjects exhibited higher nu mbers and levels of serum antibody reactions to a wide range of subgin gival species than successfully treated or periodontally healthy subje cts. Differences in serum antibody among clinical groups were more str iking at higher threshold levels of antibody (>50 mu g/ml and >100 mu g/ml). The data showed that a subject was 10.1x more likely to be refr actory if the subject exhibited antibody reactions with >9 subgingival species at >50 mu g/ml (p<0.001, after adjusting for multiple compari sons). Serum antibody to a subset of the test species differed among t he clinical groups. Porphypromonas gingivalis, Bacteroides forsythus, and some strains isolated from refractory subjects (a novel Neisseria sp., Enterococcus faecalis, Prevotella loescheii and Prevotella oulora ) elicited high serum antibody in the successfully treated and refract ory subjects. High levels of serum antibody to a Microbacterium lactic um-like organism, Streptococcus oralis, Streptococcus constellatus, Ac tinobacillus actinomycetemcomitans serotype c and Haemophilus aphrophi lus significantly increased the likelihood of a subject being refracto ry to conventional periodontal therapy.