Induction Of Periodontitis Using Bacterial Strains Isolated From The Human Oral Microbiome In An Experimental Rat Model

Abstract

Periodontal disease is that condition resulting in the destruction of periodontal tissues, bone re-sorption and tooth loss, the etiology of which is linked to immunological and microbiological factors.
 The aim of the study is to evaluate the potential trigger of periodontal disease in a rat model using the bacterial species incriminated in the pathology of human periodontitis and to establish their optimal concentration capable of reproducing the disease, with the idea of subsequently devel-oping innovative treatments for the condition.
 We included in the study 15 male Wistar rats, aged 20 weeks, which we divided into three groups. In each group, we applied ligatures with gingival retraction wire, on the maxillary incisors. 4 days/week, 4 weeks, the ligature and the gingival sac were contaminated with fresh cultures of Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus oralis in concentrations of 108, 109 and 1010CFU/ml. The clinical monitoring period was 28 days, during which we followed the expression of clinical signs specific to periodontitis, the evolution of body weight and we took weekly samples from the oral cavity for the microbiological identification of the tested bacteria and blood samples for the hematological examination. At the end of the study, the animals were euthanized and the ligated incisors were taken for histopathological analysis.
 The characteristic symptomatology of periodontal disease was expressed from the first week of the study and was maintained until the end, the bacteria being able to be identified at each examina-tion. Hematologically, the number of neutrophils decreased dramatically (P<0.0001) in the case of group 109, unlike the other groups, as did the number of lymphocytes. Histopathologically, we identified neutrophilic infiltrate in all groups. The presence of coccobacilli, periodontal tissue hyperplasia and periodontal lysis, but in group 109 we also observed pulpal tissue with necrotic bone fragments and pyogranulomatous inflammatory reaction.
 By corroborating the data, we can conclude that for the development of periodontal disease using A.a, F.n and S.o, a concentration of 109 or 1010CFU/ml is required, which must necessarily con-taminate a ligature thread applied to the level of the rat's dental pack.