Research Overview
Oral
& Maxillofacial Implants and the Bone-Implant Interface
Each year patients
receive about 250,000 hip and knee implants and about 150,000 oral and
maxillofacial implants. Such implants carry large loads during in vivo
function. Consequently, the bone-implant interface is routinely
subjected to large stresses and strains. It follows that one key
design goal with load-bearing implants is to avoid damage to interfacial
bone. While bone has a certain amount of reparative capacity, this
capacity cannot be overwhelmed.
One of the problems
is that clear danger limits for the bone-implant interface are as yet undefined.
The actual mechanical properties of bone as it exists at healed-in or immediately-loaded
interfaces are largely unknown. Moreover, the biological mechanisms
of interfacial failure remain unclear. This lack of information translates
into a largely empirical approach to commercial implant design and clinical
case planning.
What is needed
is an accurate database about the properties of the bone-implant interface
and reliable models for predicting implant loading and stress-strain conditions
at interfaces. Such data would help clinicians do better case planning,
by, for example, making it possible to estimate before surgery how many
implants should be used -- and where they should be placed in the mouth
-- to support a bridge over the long term in a given patient having specific
biting characteristics and jawbone quality. The design process could
procede as follows. (In the chart, the terms "see-saw", Skalak, SBM, etc.
refer to certain biomechanical models for predicting loading.)
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