Objective The aim of this studywas to investigate effects of immunodeficiency on the periodontal infection char- acters of the specific pathogens of juvenile periodontitis.Methods A total of 36 immunodeficient guinea pigs produced by twice whole-body irradiation with60Co were divided randomly into four groups, in whichActinobacillus actinomycetemcomitans,Porphy- romonas gingivalis, andA.actinomycetemcomitanswithP.gingivaliswere inoculated into the gingival sulcus of two mandibular inci- sors 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 examinationswere used to examine the changes in the periodontal tissues. The other36 normal guinea pigswere divided into fourgroups and treated in a similarway described above.Results Signif- icant periodontal damages were noted in immunodeficient pigs inoculated withA.actinomycetemcomitans,P.gingivalisorA.acti- nomycetemcomitansandP.gingivalisin 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
