RELATIVE AVIDITY OF SERUM ANTIBODIES TO PUTATIVE PERIODONTOPATHOGENS IN PERIODONTAL-DISEASE

ELISA was used to determine both the avidity and titre of IgG, IgA and IgM antibodies to the gram-negative anaerobe, Porphyromonas gingivalis, in twenty periodontitis patients enrolled in a longitudinal study of attachment loss and eleven non-periodontitis affected subjects. The avidity and titre of IgG antibodies to Actinobacillus Actinomycetemcomitans were also examined. A cross-sectional analysis of the longitudinal patients at baseline and non-periodontally affected controls confirmed earlier findings that IgG and IgA antibody titres to P gingivalis were higher in periodontitis patients than in individuals who were not periodontally affected. In this cross-sectional analysis, IgG antibody avidities to P gingivalis were not found to be significantly higher in periodontitis than in control subjects (p = 0.065). However, indications of the potential prognostic value of antibody avidity was demonstrated by the higher IgM avidities to P gingivalis in patients who did not experience attachment loss during the three-month monitoring period than in those who did (p = 0.0005).