Biomedical subjects

W R Flemming

Publications and source records attributed to W R Flemming.

3 recordsLinked to original sources

PubMed1980

Linear dimensional changes in elastic impression materials.

Four classes of elastomeric impression materials (polysulfide, polyether, silicone, and agar-agar) were evaluated on the basis of linear dimensional stability as a function of time between taking and pouring an impression of mounted teeth. Four polysulfide materials produced dies which were larger than the teeth and generally increased in size with impression storage time. One silicone material produced dies slightly smaller than the teeth, and the dies from another silicone were dramatically smaller with increasing storage times. A polyether material produced slightly smaller dies for up to four hours' storage time, then increasingly larger dies up to 24 h. The dies from a reversible hydrocolloid were larger than the teeth for storage times up to 30 min, and then decreased rapidly at longer times.

Agar↗

PubMed1976

Bone growth into porous high-density polyethylene.

The purpose of this study was to delineate the process by which bone comes to fill the pores of porous high-density polyethylene (PHDPE) implants. PHDPE (450 mu pore size) pellets 4 mm in diameter and 1 cm long were implanted into the femurs of dogs. A bone biopsy procedure was utilized to obtain PHDPE pellets implanted for periods of 3 days through 8 weeks. A one-year biopsy specimen taken from the PHDPE coating on the stem of a canine total-hip prosthesis was also studied. The results demonstrated that significant amounts of bone formed within the PHDPE pellets as early as 14 days after implantation. Bone was identified throughout the specimens after 4 weeks. After 6 weeks, the tissue in hematopoietic marrow. Scanning electron microscopy was utilized in conjunction with light microscopy and microradiography to study the ultrastructural features of the bone ingrowth process.

Animals↗

PubMed1975

Early tissue infiltrate in porous polyethylene implants into bone: a scanning electron microscope study.

The results of the present study demonstrate the utility of the scanning electron microscope for characterizing the ultrastructure of the initial tissue infiltrate in porous polyethylene implants. Shortly after implantation a thin noncellular fibrous-like coating was observed to form on the pore surface. The cells observed in the polyethylene pellets 3 days after implantation were generally consistent with what one would expect to see in a hematoma. As early as 14 days after implantation much of the blood clot was replaced by newly formed bone spicules. Tissue shrinkage accompanying dehydration of the specimen for scanning electron microscope study although a disadvantage occasionally proved useful in that it provided the opportunity to study the internal surface of the fibrous coating when separated from the surface of the implant. Less shrinkage was observed in implants whose pores were filled with bone spicules.

Animals↗