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Biomedical subjects

W K Adams

Publications and source records attributed to W K Adams.

6 recordsLinked to original sources
PubMed1990

A finite element survey of eleven endosseous implants.

Eleven different post-type endosseous implants were biomechanically analyzed by use of the finite element method to compile a list of features that could be used to design an optimal post-type endosseous implant. Stress magnitudes and contours within each implant and within the surrounding bone were calculated. Implant features causing high stresses and low stresses, possibly contributing to pathologic bone resorption and bone atrophy were noted. Although this preliminary survey was not complete, tentative suggestions in implant design for improved implant performance were made.

Dental Implantation, Endosseous↗
PubMed1989

Finite element analysis of bone-adapted and bone-bonded endosseous implants.

The use of bioactive coatings on endosseous implants to induce bone bonding to the implants has become popular in recent years. The actual benefit from these coatings, however, remains controversial. This study compared three endosseous implants by using finite element analysis to determine whether bone-bonding or bone-adaptation (osseo-integration) was biomechanically more beneficial. Results indicated that although a bonded interface between an implant and its host tissues may be biochemically beneficial, bone bonding, by any means, may not be biomechanically beneficial to the implant or the surrounding bone. Neither clinicians nor manufacturers should assume that bioactive coatings or bone-bonding in general improve the biomechanical prognoses of endosteal postdental implants.

Aluminum Oxide↗
PubMed1989

Bone stress distribution for three endosseous implants.

Axisymmetric finite element models of three geometries were evaluated: a serrated solid with a 2-degree taper and a rectangular cross section; a cylindrical screw-type solid; and a finned solid with a 1 degree 9' taper and a circular cross section. Ten moduli of elasticity ranging from 0.348 to 74.96 psi x 10(6) were used for each geometry. Contour plots of the resulting Von Mises stresses were used to study the changing stress distribution patterns within the surrounding cortical bone. The results indicated that the serrated geometry led to high-stress concentrations at the tips of the bony ingrowth and near the neck of the implant. Low moduli of elasticity emphasized these concentrations. The nontapered screw-type geometry had high-stress concentrations at the base of the implant when high moduli were studied and at the neck of the implant when low moduli were studied. The conclusion of this study was that a tapered endosseous implant with a high elastic modulus would be most suitable for dental implantology. However, the design must not cause high-stress concentrations at the implant neck that commonly cause bone resorption.

Alveolar Process↗
PubMed1989

Alternative materials for three endosseous implants.

Three endosseous post-type implant geometries were evaluated: a serrated solid with a 2-degree taper and a rectangular cross section, a cylindrical screw-type solid, and a finned solid with a 1-degree 9' taper and a circular cross section. Each implant geometry was analyzed with 10 different moduli of elasticity. Stress contour plots were used to identify which implant material was best suited to each implant geometry. Careful examination of all of the contour plots showed that, for all geometries, increasing the material stiffness transmitted more of the occlusal load to the apical bone. These plots further suggested that an implant material can be too stiff as the punching stresses increase at the apex of the implant. Of the three endosseous implants analyzed, only the finned solid type seemed to be made of the proper material, titanium alloy. The screw-type implant, made of sapphire, should be made of aluminum or possibly titanium. The serrated implant, made of polycrystalline alumina, was too stiff. An implant's elastic behavior is not the only governing factor. An implant's geometry seems to be the determining factor in properly distributing stresses from the implant to the bone.

Dental Alloys↗