Advances in Dental Research, Vol 13, 21-26, Copyright © 1999 by International & American Associations for Dental Research
Materials characteristics of uncoated/ceramic-coated implant materials
W. R. Lacefield
University of Alabama School of Dentistry, Biomaterials Department, Box 49, Birmingham, Alabama 35294, USA.
In this paper, the biocompatibility of dental implant materials is
discussed in the context of both the mechanical characteristics of the
materials and the type of surface presented to the surrounding tissues. The
proper functioning of the implant depends on whether it possesses the
strength necessary to withstand loading within the expected range, with
other properties such as elongation being of importance in some instances.
A suitable modulus of elasticity may be of major importance in situations
when optimum load transmission from the implant into the surrounding bone
is key to the successful functioning of the device. Dental implants present
a wide range of surfaces to the surrounding tissues based on surface
composition, texture, charge energy, and cleanliness (sterility). Metallic
implants are characterized by protective oxide layers, but ion release is
still common with these materials, and is a function of passivation state,
composition, and corrosion potential. An effective surface treatment for
titanium appears to be passivation or anodization in a suitable solution
prior to implantation. Inert ceramic surfaces exhibit minimal ion release,
but are similar to metals in that they do not form a high energy bond to
the surrounding bone. Some of the newly developed dental implant alloys
such as titanium alloys, which contain zirconium and niobium, and
high-strength ceramics such as zirconia may offer some advantages (such as
lower modulus of elasticity) over the conventional materials. Calcium
phosphate ceramic coatings are commonly used to convert metallic surfaces
into a more bioactive state and typically cause faster bone apposition.
There is a wide range of ceramic coatings containing calcium and
phosphorus, with the primary difference in many of these materials being in
the rate of ion release. Although their long-term success rate is unknown,
the calcium phosphate surfaces seem to have a higher potential for
attachment of osteoinductive agents than do uncoated titanium and other
more inert implant materials.
