Bone Density Around Endosseous Implants In Patients Taking Alendronate (Fosamax^®)

Objectives: Purpose of pilot study to non-invasively determine bone mineral density (BMD) changes around implants placed in patients administered Alendronate. BMD analyzed using quantitative computed tomography (Vitrea2™) and digital imaging.

Methods: Edentulous male patients (n=7, age 61.5±11.5 years) selected for implant placement using 2-stage system(Zimmer™). Patients requiring 2-4 implants initially seen for placement of half total number of implants unilaterally. Baseline CT scan (Siemens Sensation™ CT/I Scanner) performed on each patient. 6 months from baseline, remaining contralateral implant(s) placed, randomization into 70mg Alendronate weekly dosing/placebo groups, and second CT scan completed. Drug/placebo discontinued 12 months into study, exit CT scan completed at 12 months. No implant failures occurred during study. Total dose exposure for each CT scan = 1-2 mSv by narrowing ROI. CT axial scans (1mm slice) done to evaluate bone characteristics including BMD and 3-D topography. Hounsfield units (HU) measured at implant- and non-operated sites in maxilla/mandible and calibrated using epoxy-resin gradient phantom (CIRS®) placed against patient's face during scanning. Hounsfield units assigned by software to gradient phantom, allowing conversion of HU to BMD measurement as mg mineral/mL. DICOM data from Vitrea2™ converted to 8-bit/256 gray-scale images and analyzed using ImageJ™ v.1.35i for macroscopic bone changes. Total #CT slices analyzed=500, 14 implants.

Results:

	TSC€		GS Imaging*		BMD^
	2mmß	3mmß	2mm	3mm	2mm	3mm
Alendronate	180	180	-2.7%	-3.5%	-5.0%	-5.0% P=.01
Placebo	70	70	+3.1%	+2.7%	+1.1%	+2.5% P=.01

€ Total CT Slice Count

* 8Bit/0-256 Scale,Mean Average,%Change From Baseline

^ BMD Surrounding Implant,Mean Average,%Change From Baseline

ß Bone Radius Surrounding Implant

Conclusions: 6-month dosing with Alendronate negatively influences BMD at implant/bone interface only if drug administration starts at time of implant placement. No statistically significant BMD changes observed around implants placed 6 months prior to Alendronate dosing. Supported by Veterans Administration Grant #04-069/Merck US-IISP Grant #29268.