This study aimed to evaluate the influence of
estrogen deficiency and mechanical loading on bone around osseointegrated
dental implants in a rat jaw model. The maxillary right first molars of 36 rats were extracted. One week later, the rats were divided into an unloaded group and a loaded group; short head implants and long head implants were inserted respectively. Nine weeks after implantation, the rats were further subjected to
ovariectomy (OVX) or
sham surgery. All animals were euthanized 21 weeks after OVX. Micro-computed tomography, histological and histomorphometrical evaluation were undertaken. Systemic bone mineral density and bone volume fraction decreased in OVX groups compared with the
sham controls. Histomorphometrical observation indicated that unloaded OVX group showed significantly damaged osseointegration and bone loss versus the loaded OVX group. Both the bone density (BD) inside the peri-implant grooves and the percentage of bone-to-implant contact (
BIC) were lower in the OVX groups than in the
sham-surgery groups, although mechanical loading increased the
BIC and BD in the loaded OVX group compared with the unloaded OVX group. An increased number of positive cells for
tartrate-resistant acid phosphatase was observed in the OVX groups versus the
sham controls. The percentage of sclerostin-positive osteocytes was lower under loaded compared with unloaded conditions in both the OVX groups and the
sham controls. In conclusion,
estrogen deficiency could be a risk factor for the long-term stability of
osseointegrated implants, while mechanical loading could attenuate the negative influence of
estrogen deficiency on bone formation and osseointegration.