ABSTRACT
<p><b>OBJECTIVE</b>The aim of this study was to investigate effects of immunodeficiency on the periodontal infection characters of the specific pathogens of juvenile periodontitis.</p><p><b>METHODS</b>A total of 36 immunodeficient guinea pigs produced by twice whole-body irradiation with 60Co were divided randomly into four groups, in which Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and A. actinomycetemcomitans with P. gingivalis were inoculated into the gingival sulcus of two mandibular incisors respectively. The pigs in the control group did not receive any inoculation. At 2, 3 and 6 weeks after inoculation, three animals in each group were sacrificed successively. Clinical and histological examinations were used to examine the changes in the periodontal tissues. The other 36 normal guinea pigs were divided into four groups and treated in a similar way described above.</p><p><b>RESULTS</b>Significant periodontal damages were noted in immunodeficient pigs inoculated with A. actinomycetemcomitans, P. gingivalis or A. actinomycetemcomitans and P. gingivalis in 2 and 3 weeks after bacterial inoculation. The damages were more severe than in the normal groups. The immunodeficient groups demonstrated larger numbers of osteoclasts than the normal groups (P < 0.05).</p><p><b>CONCLUSION</b>The loss of periodontal tissue in immunodeficient hosts is much serious than those with normal defence system, after they are infected with A. actinomycetemcomitans and P. gingivalis. Abnormal defence system in hosts may play an important role in onset and development of juvenile periodontitis.</p>