Effects of Estrogen Deficiency and/or Caffeine Intake on Alveolar Bone Loss, Density, and Healing: A Study in Rats

Background: 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). Methods: 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. Results: 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). Conclusions: Caffeine increased BL in ligated teeth. Caffeine and/or estrogen deficiency decreased TBA in the unligated teeth and reduced BH after tooth extraction.