Effects of estrogen deficiency and/or caffeine intake on alveolar bone loss, density, and healing: a study in rats

The aim of this study is to evaluate the effects of caffeine and/or estrogen deficiency on ligature-induced bone loss (BL), trabecular bone area (TBA), and postextraction bone healing (BH).

Rats were assigned into one of the following groups (15 each): 1) control = non-ingestion of caffeine/sham surgery; 2) caffeine = ingestion of caffeine/sham surgery); 3) ovariectomized (OVX) = non-ingestion of caffeine/ovariectomy; or 4) caffeine/OVX = ingestion of caffeine/ovariectomy. The rats were under caffeine administration for 65 days and/or estrogen deficiency for 51 days. On day 21 after ovariectomy, one first mandibular molar received a ligature and the contralateral tooth was not ligated. The first maxillary molars were extracted 8 days before sacrifice. BL, TBA, the positive cells for tartrate-resistant acid phosphatase (TRAP), receptor activator of nuclear factor-κB ligand (RANKL), and osteoprotegerin (OPG) were analyzed in the furcation area of mandibular molars. Histometric BH and gene expression of bone morphogenetic protein (BMP)-2, BMP-7, osteopontin, and bone sialoprotein were evaluated in alveolar sockets.

The caffeine group presented the greatest BL and the OVX group the highest number of TRAP-positive (TRAP(+)) cells around ligated teeth (P <0.05). The control group presented higher TBA and BH than the other groups (P <0.05). All test groups presented higher RANKL/OPG(+) cells than the control group around ligated/unligated teeth. The OVX and caffeine/OVX groups presented a greater number of TRAP(+) cells around unligated teeth than the control group (P <0.05). There were no differences among groups for gene expression (P >0.05).

Caffeine increased BL in ligated teeth. Caffeine and/or estrogen deficiency decreased TBA in the unligated teeth and reduced BH after tooth extraction.