Effect of intermittent PTH administration in the periodontitis-associated bone loss in ovariectomized rats.
OBJECTIVE
Parathyroid hormone intermittent administration has been considered to treat bone mass decrease in osteoporotic individuals. The present study evaluates whether PTH can affect alveolar bone loss in ovariectomized rats, since estrogen deficiency has been proposed as a risk factor for periodontal disease.


METHODS
Thirty female rats were set in groups: ovariectomized (Ovx) and Sham operated. Ovx were divided in two groups: Ovx-PTH (1-34) treated and Ovx, which received vehicle. After 1 week, cotton ligature was placed around one lower first molar of all animals to induce periodontal disease. Ovx treated received PTH doses of 40 microg/kg, three times a week for 30 days. After that, the animals were sacrificed, the mandibles extracted, X-rayed and samples prepared for histological evaluation. Histomorphometry was performed using image analyzer software. Scanning electron microscopy (SEM) of the tibias was also performed in all animals to evaluate possible changes in bone structure caused by the estrogen deficiency. Optical densities of the radiographs were measured by aluminum step-wedge equivalent thickness.


RESULTS
Histomorphomery indicated the anabolic PTH effect in ovariectomized rats with significant inhibition of periodontitis manifestation (p<0.05) thus neutralizing the periodontitis inductor effects. The photo densitometry showed a lower mandibular optical density in the ovariectomized group that did not receive PTH (p<0.05). SEM image confirmed the early effect of estrogen deficiency in osseous tissue and PTH anabolic effect.


CONCLUSIONS
PTH systemic intermittent administration was able to reduce alveolar bone loss in ovariectomized rats, despite the presence of a periodontal disease inductor and estrogen deficiency.
Marques
Marcelo Rocha
MR
Department of Morphology, Division of Histology, School of Dentistry at Piracicaba, University of Campinas, Av. Limeria, 901, 13414-903 Piracicaba, SP, Brazil.
da Silva
Marco Antônio Dias
MA
Manzi
Flávio Ricardo
FR
Cesar-Neto
João Batista
JB
Nociti
Francisco Humberto
FH
Barros
Silvana Pereira
SP
D015502:Absorptiometry, Photon; D016301:Alveolar Bone Loss / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D000818:Animals; D004334:Drug Administration Schedule; D005260:Female; D007091:Image Processing, Computer-Assisted; D008334:Mandible / Q000000981:diagnostic imaging; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D010024:Osteoporosis / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000008:administration & dosage* / Q000627:therapeutic use; D010446:Peptide Fragments / Q000008:administration & dosage* / Q000627:therapeutic use; D010518:Periodontitis / Q000150:complications / Q000000981:diagnostic imaging / Q000188:drug therapy*; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia / Q000648:ultrastructure
D010281:Parathyroid Hormone; D010446:Peptide Fragments