Additive effects of estrogen replacement therapy and bisphosphonates on osseointegration of hydroxyapatite-coated titanium screws in ovariectomized rats

Li, Yunfeng DDS
Gao, Ying DDS, PhD
Song, Guodong DDS
Liu, Xianwen DDS
Hu, Jing DDS, PhD

^aResearch fellow, State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, Sichuan, China
^bFaculty, Department of Oral & Maxillofacial Surgery, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, China

^*Reprint requests: Dr. Jing Hu, DDS, PhD, West China College of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, China [email protected]

Supported by a grant from National Science Funds for Distinguished Young Scholars (no. 30825040).

Received for publication August 1, 2009; returned for revision October 1, 2009; accepted for publication October 16, 2009

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, & Endodontics 109(5):p 700-705, May 2010.

Objective

This study investigated the effect of locally immobilized bisphosphonates and systemic estrogen replacement therapy on fixation of hydroxyapatite-coated screws in ovariectomized rats.

Study design

Twelve weeks after being ovariectomized, each of the 20 rats received 2 hydroxyapatite-coated screws in the proximal tibia, with or without immobilized bisphosphonates. Half of the animals also received subcutaneous injections of 17β-estradiol. Thus, there were 4 groups: control, estrogen, bisphosphonates, and estrogen plus bisphosphonates. Tibiae with screws were measured by microscopic computerized tomography and push-out test 12 weeks after implantation.

Results

Combined treatment had the strongest effects, with the bone volume ratio around screws and the percentage of osteointegration significantly increased by 2.3-fold and 1.9-fold and the push-out force by 3.3-fold compared with untreated control samples. Monotherapy also enhanced the fixation of screws, although less.

Conclusions

Systemic estrogen replacement therapy and locally immobilized bisphosphonates had additive effects on fixation of hydroxyapatite-coated screws in ovariectomized rats.