The Colonization and Establishment of Invading Bacteria in Periodontium of Ligature‐Treated Immunosuppressed Rats

Abstract

The morphologic features and pattern of bacterial invasion of the periodontal tissue in ligature‐induced periodontal defects of immunosuppressed rats were studied. Silk ligatures were placed circumferentially on the maxillary left second molar of 24 Sprague‐Dawley rats. The treatment group (14 rats) received Cytoxan (75 mg/kg) the day after ligature placement and at Day 4. The control group (10 rats) received no medication. All animals were sacrificed on Day 8 and the maxillae processed for light and electron microscopy. Only ligated sites in immunosuppressed animals exhibited bacterial invasion. Invading bacteria consisted of microcolonies of Gram‐negative and Gram‐positive coccoid cells and rods located near the tissue surface. Each microcolony consisted of morphologically homogeneous microorganisms. The deeper sites revealed a diffuse invasion of Gram‐negative rods which appeared morphologically similar. Other features associated with invasion were complete destruction of epithelial tissue next to the ligature and the lack of inflammatory cells in the gingival region. These findings, when compared to those of other reports of tissue penetration by bacteria, point to the necessity of differentiating between bacterial invasion of gingival tissues, associated with penetration of tissues by proliferating bacteria, and bacterial translocation, a situation in which bacteria are passively carried into the tissues, for example by mechanical manipulation immediately before or during biopsy taking, or possibly during processing for histology.

The Adaptive Nature of the Bone-Periodontal Ligament-Cementum Complex in a Ligature-Induced Periodontitis Rat Model

“…The combined effect can result in positive or negative feedback, thus shifting organ function to impairment. Even though comprehensive studies have postulated a cause-and-effect relationship between bacteria and/or inflammatory cytokines and tissue destruction [44–51], they are spatially limited and describe only alveolar bone destruction. As a result, studies are needed to illustrate effects on the entire bone-PDL-cementum complex, in which the role of no one tissue dominates specifically when in function.…”

Porphyromonas gingivalisRgpA-Kgp Proteinase-Adhesin Complexes Penetrate Gingival Tissue and Induce Proinflammatory Cytokines or Apoptosis in a Concentration-Dependent Manner

“…While it is possible that the spots represented P. gingivalis cells, evidence from histological investigations suggests that active invasion of chronic periodontitis tissue by whole bacterial cells is limited and difficult to confirm in naturally occurring disease (40,41,69,78).…”

Expressions of Interleukin-1β and Interleukin-6 Within Aortas and Uteri of Rats with Various Severities of Ligature-Induced Periodontitis

“…The distances from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) within the placement zone of the ligature and their contralateral zone in groups L 2 and L 3 were measured using a modification of the method described by Sanavi et al [41]. Figure 1 shows that measurements were made along the long axial direction of the oral root surfaces of a ligatured tooth and its contralateral tooth using a light microscope with a camera mounted on a computer (XLT-340E, Shanghai Changfang Optical Instrument Co. Ltd., Shanghai, China) in a standardised manner (×10 magnification).…”