Biomedical subjects

J A Von Fraunhofer

Publications and source records attributed to J A Von Fraunhofer.

At least 19 recordsLinked to original sources

PubMed1998

Dental cutting: the historical development of diamond burs.

This brief history of the dental diamond bur is intended to provide both a historical perspective and an evaluation of the current state of bur technology. An understanding of the origins of dental diamonds and the issues facing manufacturers transforms the dentist from a simple user into an informed consumer. The author contends that this can improve dental care and enable the dentist to collaborate with manufacturers in developing improved dental burs.

Dental High-Speed Equipment↗

PubMed1987

Heat of intramedullary reaming.

Cortical ischemia and necrosis after intramedullary reaming are well documented. Numerous authors have described ischemic changes attributed to mechanical disruption of the arterial system of the intramedullary canal. Few have investigated the potential thermal injury during extreme temperatures generated during intramedullary reaming. We reamed the medullary canal of cadaveric tibial and femoral diaphyses using a flexible shaft reaming device and stainless steel intramedullary reamer. The temperatures generated by reaming from 11 mm through 15 mm in 1 mm increments were measured after each pass. In the 17 specimens tested, we observed an incremental rise in temperature with reaming. The mean intramedullary temperature after reaming was 52 C ( +/- 8.3) with a range of 42 to 67 C. The mean extramedullary temperature was 46 C ( +/- 8.3) with a range of 36 to 59 C. There was a direct correlation between temperature increase and reamer size. Our results indicate that temperature elevations generated during intramedullary reaming are sufficient to cause thermal necrosis, and may cause delayed healing in vivo.

Aged↗

PubMed1985

In vitro characteristics of tobramycin-PMMA beads: compressive strength and leaching.

Antibiotic-impregnated polymethylmethacrylate (PMMA) bone cement beads have been used as a local drug delivery system for the treatment of bone and soft tissue infections. The beads deliver a high local level of antibiotic with a decreased risk of toxic systemic levels. This study was undertaken to determine the antibiotic release characteristics of tobramycin-impregnated beads over time and to determine the compressive strength of these beads. Acrylic resin (PMMA) bone cement beads were prepared with three different concentrations of tobramycin. The beads were tested for compressive strength, and their antibiotic release characteristics were determined over a 21 day period by radioimmunoassay and by biological testing against a variety of bacteria. The compressive strength of the beads was found to be adequate to avoid fragmentation during their clinical use. There was gradual release of tobramycin from the beads over the entire 21 days, but the release was most marked during the first 48 hours. There was antibiotic activity against both gram-negative and gram-positive organisms, except Enterococcus, for the entire 21 day period. The release of tobramycin followed a curvilinear relationship and was directly related to the initial antibiotic concentration of the bead. Tobramycin-impregnated polymethylmethacrylate beads may represent a reliable method of local antibiotic delivery with sustained activity against a broad spectrum of organisms.

Bone Cements↗

PubMed1981

The interaction between lining materials and composite resin restorative materials.

The effects of four lining materials, Dycal, Procal, Cavitec and Poly F cement on Adaptic and Concise have been investigated in vitro. The parameters studied were surface roughness, hardness and colour both with and without an intermediate (or bonding) resin being present between the restorative material and the liner. The effects of the four liners on the composites varied both between the lining materials themselves and with the composite resin. Two materials, Procal and Dycal, had little interaction with the composites, provided an intermediate resin was used with the latter. Cavitec appeared to have an adverse reaction with the composites and Poly F, whilst having no effect on the colour of the composites, did increase surface roughness. The adverse effects of linig materials were ascribed to minor constituents, particularly methyl salicylate, present in the formulation.

Acrylic Resins↗

PubMed1976

Etching of enamel prior to application of fissure sealants.

Acid etching has been shown to be necessary to increase the bond strength of the polymeric fissure sealants Epoxylite 9075 and Nuva Seal to enamel. For Nuva Seal or Epoxylite 9075 it would appear that it does not matter which concentration between the concentration levels of 30 and 70% is used.

Dental Bonding↗

PubMed1975

The bonding of a polymeric fissure sealant to topical fluoride-treated teeth.

The tensile bond strength of a polymeric fissure sealant to enamel treated with a variety of topical fluorides was determined. Application of acidulated phosphate fluoride solutions (APF) prior to and after acid etching reduces the tensile bond strength of Nuva Seal from 36-6+/-9-0 kg/cm2 to 4-9+/-3-3 kg/cm2 and 23-8+/-6-3 kg/cm2 respectively. The treatment of the etched enamel with freshly prepared 8% stannous fluoride solution prior to Nuva Seal application significantly increases the tensile bond strength to 55-7+/-17-1 kg/cm2. It is recommended that clinical procedures such as the application of fissure sealants, acid etch composite restorations and the direct attachment of orthodontic brackets, all of which involve etching of the enamel, should not be precedded by the topical application of APF solutions.

Dental Bonding↗

PubMed1974