Effect of an estrogen-deficient state and its therapy on bone loss resulting from an experimental periodontitis in rats.
OBJECTIVE
The aim of this study was to evaluate the impact of an estrogen-deficient state and its therapies (estrogen and calcitonin administration) upon bone loss resulting from an experimental periodontitis.


METHODS
Fifty-eight Wistar rats were divided into four groups: group 1 (n = 15): sham operated; group 2 (n = 15): ovariectomized; group 3 (n = 14): ovariectomized plus calcitonin administration; group 4 (n = 14): ovariectomized plus estrogen administration. Twenty-one days after ovariectomy or sham surgeries, the ligature was randomly placed. Sixty days later, the animals were killed and the specimens routinely processed. In addition, serum levels of alkaline phosphatase and calcium were assessed.


RESULTS
Intergroup analysis revealed that an estrogen-deficient state significantly increased bone loss resulting from periodontitis and that such an effect could not be prevented either by estrogen or calcitonin administration (0.34 +/- 0.13, 0.65 +/- 0.06, 0.63 +/- 0.19, 0.67 +/- 0.28 for groups 1, 2, 3 and 4, respectively). Furthermore, an estrogen-deficient state presented a direct effect on the alveolar bone regardless of plaque accumulation and this effect may be significantly reduced by estrogen administration (p < 0.05). Serum analysis demonstrated a higher bone turnover for the animals with estrogen deficiency, and estrogen therapy restored bone metabolism.


CONCLUSIONS
Estrogen administration may prevent the direct effect of an estrogen-deficient state on alveolar bone; however, neither estrogen nor calcitonin administration could prevent this effect when associated with a response to a plaque-related inflammatory process.
Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, UNICAMP, Piracicaba, São Paulo, Brazil.
Poliana Mendes
PM
Duarte
Patricia Furtado
PF
Gonçalves
Antonio Wilson
AW
Sallum
Enilson Antonio
EA
Sallum
Marcio Zaffalon
MZ
Casati
Francisco
F
Humberto Nociti
D000469:Alkaline Phosphatase / Q000097:blood; D016301:Alveolar Bone Loss / Q000209:etiology* / Q000473:pathology; D000704:Analysis of Variance; D000818:Animals; D002116:Calcitonin / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D003773:Dental Plaque / Q000150:complications; D004958:Estradiol / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000172:deficiency*; D005260:Female; D007091:Image Processing, Computer-Assisted; D008026:Ligation / Q000295:instrumentation; D016555:Matched-Pair Analysis; D010052:Ovariectomy; D010518:Periodontitis / Q000150:complications*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D004967:Estrogens; D004958:Estradiol; D002116:Calcitonin; D000469:Alkaline Phosphatase; D002118:Calcium