Influence of estrogen status on endosseous implant osseointegration

Purpose: This retrospective study tested the hypothesis that postmenopausal women have lower rates of osseointegration of endosseous implants than premenopausal women and male controls. The role of estrogen replacement therapy (ERT) was also evaluated.

Patients and methods: Review of medical records allowed identification of patients who had received endosseous implants. Patients with concurrent illness, a smoking or ethanol use history, or metabolic bone disease were excluded. Five groups of subjects were identified: 1) 168 postmenopausal women without ERT; 2) 75 postmenopausal women supplemented with ERT; 3) 114 premenopausal women; 4) 59 men younger than 50 years; and 5) 110 men older than 50 years. Successful osseointegration was defined as stability at uncovering using a manual torque wrench and was confirmed radiographically. Failure rate comparisons were made between groups using both Fisher's exact tests and Poisson regression models.

Results: Postmenopausal women without ERT had the highest maxillary failure rate (13.6%) which was significantly greater than for premenopausal women (6.3%, P =.039) and for men older than 50 (7.6%, P =.051). Although the maxillary failure rate of unsupplemented postmenopausal women was greater than for ERT supplemented women (8.1%), the comparison did not reach statistical significance (P =.17). The maxillary failure rate was similar between men younger than 50 years and those older than 50 years (6.3 vs 7.6%, not significant) Mandibular implant failures in all groups showed no statistically significant differences.

Conclusion: The effect of postmenopausal estrogen status on compromised implant healing was shown in the maxilla but not in the mandible. Unsupplemented postmenopausal women had the highest failure rate. Although a statistical difference was not achieved, ERT reduced the maxillary failure rate by 41%. These results suggest that estrogen deficiency and the resultant bony changes associated with menopause may be risk factors for endosseous implant failure in the maxilla.