Search PubMed⌕ Search

Biomedical subjects

V C West

Publications and source records attributed to V C West.

31 records · Page 2Linked to original sources
PubMed1984

Force relaxation in orthodontic arch wires.

Wire selection for use in an orthodontic appliance is usually based upon clinical impressions. This is unsatisfactory. A far better basis for selection would be measured values of the forces exerted by the arch wire, both initially on insertion of the appliance and their variation with time as a result of tooth movement and of stress relaxation in the wire. An apparatus has been designed to measure force relaxation in orthodontic arch wires shaped into a representative arch form. Measurements of the force relaxation have been made in stainless steel, Elgiloy, and nitinol wires at 21 degrees C and 37 degrees C. All the wires were found to relax at 21 degrees C, but no relaxation was observed in nitinol at 37 degrees C. The rates of relaxation were found to vary widely; stainless steel wires produced by Wilcock in Australia relaxed significantly less than Elgiloy wires. A heat treatment performed on green Elgiloy eliminated the relaxation altogether and had a significant but lesser effect on blue Elgiloy.

Alloys↗
PubMed1983

Growth in the area of the inferior dental foramen of rats.

The object of the present investigation was to see if the bone around the inferior dental nerve remodelled during mandibular growth and development. The investigation was carried out by injecting 27 albino Lewis rats with three fluorescent bone seeking dyes--oxytetracycline HCl (OTC), alizarin red S (ARS), and 2,4 bis-[N,N'-di' (carbomethyl-aminomethyl)] fluorescein (DCAF)--and then studying the bone around the inferior dental foramen. The mandibles of the animals were studied both macroscopically and microscopically under ultraviolet light to investigate the growth processes occurring and to see if the inferior dental foramen was relocated during growth. A quantitative analysis utilizing two specimens was also carried out for the same purpose. The results of both the qualitative and the quantitative analyses showed that the bone around the inferior dental nerve remodeled during mandibular growth. The mandible grew in an upward and backward direction, and the inferior dental foramen was correspondingly relocated in an upward and backward direction to maintain exactly the same position relative to the condyle and the posterior border of the ramus. This study, then, supports Moss's concept of the "unloaded" nerve, and is in keeping with his view of mandibular growth based on the functional matrix theory.

Animals↗
PubMed1977

An electron microprobe analysis of osteofluorosis in the rabbit.

Osteofluorosis was induced in rabbits by the ingestion of 500 ppm F in their drinking water over a period of 30 days. The tibiae from experimental and control animals were selected for macroscopic, microscopic and microradiographic observation. Transverse sections of 100 mum thickness were prepared for an electron-microprobe analysis to determine Ca, P and F concentrations and to display the topographical distribution of F as revealed by the X-ray image of its Kalpha1 radiation. Variation in amount of periosteal and endosteal deposition was observed along the length of the bone. Changes, including numerous mottled osteones, were seen in the compact zone of bone which had been formed prior to the start of the experiment. The Ca/P ratio appeared to show a variation related to the F concentration.

Animals↗