Although the pla
cement of dental and orthopedi
c implants is now generall
y a safe, reliable and su
ccessful undertaking, the fun
ctional out
come is less assured in patients whose bone-healing
capa
cit
y is
compromised. To enhan
ce peri-implant osteogenesis in these individuals, BMP-2
could be lo
call
y administered. However, neither a free suspension nor an implant-adsorbed depot of the agent is
capable of triggering sustained bone formation. We h
ypothesize that this end
could be a
chieved b
y in
corporating BMP-2 into the three-dimensional
cr
ystalline latti
cework of a bone-mineral like,
cal
cium-phosphate implant
coating, wherefrom it would be liberated graduall
y - as the inorgani
c la
yer undergoes osteo
clast-mediated degradation - not rapidl
y, as from an implant-adsorbed (two-dimensional) depot. To test this postulate, we
compared the osteoindu
ctive effi
ca
cies of implant
coatings bearing either an in
corporated, an adorbed, or an in
corporated and an adsorbed depot of BMP-2 at a maxillar
y site in miniature pigs. The implants were retrieved 1, 2 and 3 weeks after surger
y for the histomorphometri
c anal
ysis of bone formation within a defined 鈥榦steoindu
ctive鈥?spa
ce.
At each juncture, the volume of newly-formed bone within the osteoinductive space was greatest around implants that bore a coating-incorporated depot of BMP-2, peak osteogenic activity being attained during the first week and sustained thereafter. In the other groups, the temporal course of bone formation was variable, and the peak levels were not sustained.
The findings of this study confirm our hypothesis: they demonstrate that we now have at our disposal a means of efficaciously augmenting and expediting peri-implant bone formation. Clinically, this possibility would render the process of implant placement a safer and a more reliable undertaking in patients whose bone-healing capacity is compromised, and would also permit a curtailment of the postoperative recovery period by a forestallment of the mechanical-loading phase.