Artificial periodontal defects around incisor teeth of beagle dogs

The aim of the present experiment was to investigate if it is possible to create deep periodontal defects around incisor teeth of beagle dogs with the use of orthodontic elastic bands, to investigate if this method is reproducible and predictable, and to evaluate if such defects possess the histopathological characteristics of naturally occurring periodontitis. In eight beagle dogs the dentogingival fibres around four upper incisors, ³I₃ and ²I₂, were cut to the level of the alveolar bone. Orthodontic elastic bands were placed in these deepened sulci and removed after 8 weeks. Clinical data (probing depth and gingival recession) were recorded at the start of the experiment, immediately following removal of the elastic bands, and 2, 6, 14, and 30 weeks thereafter. The dogs were sacrificed on different dates so that is was possible to analyse defects histometrically 3, 7, 15, or 31 weeks after elastic removal. Contralateral defects one week after elastic band removal served as controls. Micrographic color slides of the histological sections were analysed using a Ferranti-Cetec digitizer. Immediately after elastic band removal mean values for probing depth and gingival recession were approximately 5.5 mm and 2.0 mm, respectively. Histometrical assessments revealed a loss of attachment of approximately 3.0 mm. The differences in probing depths between Contralateral defects in the same dog were small indicating rather high reproducibility of the method. Because of wide variations in probing depth and histometrical dimensions between dogs, it was concluded that the present method is not fully predictable. Upon elastic removal values for probing depth decreased with approximately 1.5 mm, the result being a moderately deep defect of around 4 mm. Histometrically there was no evidence that the apical positioning of the junctional epithelium was reversible after elastic removal. However, alveolar bone repair could be demonstrated in the 7, 15, and 31 weeks specimens. It was concluded that because of this bone repair, the present defects do not possess all histopathological characteristics of naturally occurring periodontitis.