Biomedical subjects

M I Lifland

Publications and source records attributed to M I Lifland.

5 recordsLinked to original sources

PubMed1997

Composite titanium dental implant fabricated by electro-discharge compaction.

An electro-discharge compaction (EDC) fabrication window was established for producing commercially pure porous titanium dental implants of 4 mm diameter and 7 mm length with a solid titanium cap. The optimum input energy was in the range of 0.58-0.87 kJ g-1 for a powder column of 0.500 g. Input energy greater than 0.58 kJ g-1 resulted in an implant torque strength exceeding 30 N-cm (the retaining screw tightening torque), while input energy greater than 0.72 kJ g-1 exceeded 46.7 N-cm torque strength (at this level the retaining screw failed prior to the implant). The integrity of the internally threaded hole and hexagonal head of the cap were maintained throughout the EDC process. The EDC process did not after the strength and/or microstructure of the components, and the bead-cap interface was stronger than the bead-bead interface. EDC implants produced within the aforementioned window have sufficient compressive strengths and other physical properties to meet the requirement for titanium dental implants.

Biocompatible Materials↗

PubMed1995

A light and scanning electron microscopic evaluation of electro-discharge-compacted porous titanium implants in rabbit tibia.

This study used light and scanning electron microscopic (SEM) histomorphometric methods to quantitate the rate of osseointegration of totally porous titanium alloy (Ti-6Al-4V) implants prepared by a novel fabrication technique--electrodischarge compaction (EDC). EDC was used to fuse 150-250-micrometer spherical titanium alloy beads into 4 X 6 mm cylindrical implants through application of a 300-microsecond pulse of high-voltage/high-current density. Two sterilized implants were surgically placed into each tibia of 20 New Zealand white rabbits and left in situ for periods corresponding to 2, 4, 8, 12, and 24 weeks. At each time point, 4 rabbits were humanely killed, and the implants with surrounding bone were removed, fixed, and sectioned for light and SEM studies. The degree of osseointegration was quantitated by means of a True Grid Digitizing Pad and Jandel Scan Version 3.9 software on an IBM PS/2 computer. The total pore area occupied by bone was divided by the total pore area available for bone ingrowth, and a Bone Ingrowth Factor (BIF) was calculated as a percent. The light microscopic results showed BIFs of 4% at week 2, 47% at week 4, 62% at week 8, 84% at week 12, and greater than 90% at week 24. The SEM results showed BIFs of 5% at week 2, 34% at week 4, 69% at week 8, 75% at week 12, and in excess of 90% at week 24. The results of this study show that EDC implants are biocompatible and support rapid osseointegration in the rabbit tibia and suggest that, after additional studies, they may be suitable for use as dental implants in humans.

Alloys↗

PubMed1994

Properties of titanium dental implants produced by electro-discharge compaction.

Highly porous dental implants of a cylindrical shape were fabricated from commercial grade titanium REP-atomized powders by EDC. They were intended to have the maximum porosity for maximum osseointegration, but to maintain the minimum mechanical properties functionally required. Two level full factorial experiments were conducted with respect to the sample weight, capacitance, input energy and electrode configuration. All samples were X-rayed prior to tests to ascertain the presence, extent and distribution of internal macroscopic voids. Torque and compression tests were conducted to evaluate the yield or ultimate strengths (34-90 cm N and 205-502 MPa, respectively). These results indicate that macroscopic void-free, highly porous implants can be fabricated.

Dental Implants↗

PubMed1994

An evaluation of electrodischarged prototype implants in rabbit tibia: a preliminary study.

This is the first in a series of biological investigations using a porous implant fabricated by a novel process known as electrodischarge compaction (EDC). This process uses Ti-6A1-4V powder and electrical energy to construct a beaded porous implant without any compromise in physical characteristics, often found with conventional sintering. The purpose of this study was to evaluate the bone response in rabbit tibia of a porous titanium prototype implant fabricated by this new technique. One hundred forty-four porous EDC-fabricated implants were placed into the tibia of 36 New Zealand rabbits. Animals were placed into one of six time periods (2, 4, 8, 12, 18, and 24 weeks). At the appropriate time period, animals were killed, and bone ingrowth was evaluated qualitatively by light and scanning electron microscopy. Bone/implant interface bond strength was also measured. Slight bone ingrowth was observed as early as the two-week time period and increased in depth at each time period for the duration of the study. Implant/bone bond strength was measurable at four weeks and continued until reaching a plateau at week 12. The results of this study suggest that this novel EDC implant may be suitable for continued development of an easily fabricated, cost-effective dental implant.

Aluminum↗

PubMed1993

Mechanical properties of a Ti-6A1-4V dental implant produced by electro-discharge compaction.

Cylindrical, porous-surfaced implants were fabricated from Ti-6A1-4V atomized powders by an electro-discharge compaction technique (EDC). Input energy (1-2.5 kJ/g powder) was used to produce implant compacts having a solid core surrounded by a porous layer. The solid core size, neck size between core and particle, neck size between particles, and pore size in the porous layer varied as input energy was changed. Compression tests were carried out to evaluate the mechanical properties of the EDC compacts. The yield strength ranged from 270 to 530 MPa and the ultimate compressive strengths ranged from 390 to 600 MPa. The yield strengths for solid core, core-particle and particle-particle interfaces remained constant at 755 MPa regardless of input energy. The endurance limits estimated from these results were 190-310 MPa, which were higher than the reported values for sintered titanium implants. Microhardness testing revealed that hardness was independent of input energy and the position where the testing indentation was applied. The average hardness of the compacts was 3430 MPa.

Aluminum↗