title: Early steps in bone resorption in experimental periodontitis: a histomorphometric study.
abstract: A histomorphometric study of the initial steps in the process of bone resorption of inflammatory origin is presented. The study was performed in a model of experimental periodontitis, in which plaque formation is induced by means of a cotton thread ligature placed around the neck of the first molar of Wistar rats. The treated animals were killed in groups after 24, 48, 72 and 96 hours. An equivalent number of untreated rats were employed as controls. After routine histologic processing mesiodistal sections were obtained. The histologic studies showed the sequence of events of the inflammatory process and bone resorption. The histomorphometric studies showed the concomitant increase in erosive areas and number of osteoclasts with the highest values at 72 hours. At 96 hours both parameters decreased. The results are discussed in the light of those afforded by other experimental models, in which bone resorption is induced by orthodontic forces. In these models the increase in the resorptive areas precedes the increase in the number of osteoclasts. The existence of two different mechanisms for the initiation of bone resorption, one which involves the action of an inflammatory environment and the other which results from the action of mechanical forces, is proposed.
authors.affiliation: Department of Oral Pathology, Faculty of Dentistry, University of Buenos Aires, Department of Radiobiology, National Atomic Energy Commission, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Ubios
authors.forename: O R
authors.initials: OR
authors.lastname: Costa
authors.forename: R L
authors.initials: RL
authors.lastname: Cabrini
mesh_terms: D016301:Alveolar Bone Loss / Q000209:etiology / Q000473:pathology*; D000818:Animals; D004195:Disease Models, Animal; D008026:Ligation; D008297:Male; D010010:Osteoclasts / Q000502:physiology; D010518:Periodontitis / Q000150:complications; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical