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Biomedical subjects

V C West

Publications and source records attributed to V C West.

17 recordsLinked to original sources
PubMed1992

The effect of acetylsalicylic acid on orthodontic tooth movement in the guinea pig.

This study examined the influence of acetylsalicylic acid an inhibitor of prostaglandin synthesis, on orthodontic tooth movement induced with light spring forces in the guinea pig. The animal model was shown to permit reliable and accurate recording of tooth movement up to 28 days. Tooth movement was found to be highly correlated with spring forces, indicating that the model provided a sensitive test of the effect of aspirin on tooth movement. Aspirin was administered orally at the rate of 65 mg/kg per day in three divided doses and was found to effectively inhibit prostaglandin synthesis at the level of the bronchioles. However, aspirin did not appear to significantly affect tooth movement. Thus prostaglandins may not be the only mediators of the bone resorption associated with tooth movement induced by light orthodontic forces under these experimental conditions.

Analysis of Variance↗
PubMed1991

Friction ... Friction resistance between edgewise brackets and archwires.

This study quantified the dynamic frictional force encountered when TMA, Orthonol and multistranded stainless steel archwires were pulled a distance of 2mm through ceramic and stainless steel brackets. The current literature is inadequate and incomplete, for example, no data was found on rectangular multistranded archwires. The following factors were investigated: archwire material, archwire size, archwire-to-bracket angulation, bracket material, archwire and bracket slot surface roughness and lubrication in the form of artificial saliva. A total of 156 different combinations were investigated. A universal testing machine was used to pull the ligated archwires through the brackets, and record the friction. A four way analysis of variance with one nesting (archwire size) was carried out on 1,560 measurements to assess the results. All factors and interactions tested were significant in determining friction. Friction was found to increase with: archwire angulation and archwire size (exceptions were seen in some TMA archwires). Friction decreased with lubrication. There was a definite relationship between friction and archwire and bracket material. There was no definite relationship between archwire surface roughness and friction. Highest friction was observed with ceramic bracket and TMA archwire. The range of friction was 1.02 to 9.95 Newtons. The magnitude of the friction recorded is substantially larger than the forces applied in orthodontic movement clinically. It is proposed that the values recorded should be utilised as a means of comparing the effects of different factors, rather than for the quantification of friction in vivo.

Analysis of Variance↗
PubMed1989

A method of recording condylar movements and joint sounds.

A commercial tracking system has been adapted within the University of Melbourne, which is designed to track the movement of infra-red light emitting diodes (LEDs). The movement of the diodes was recorded by photosensimetric recording devices, and sent to a data recorder, then to a differential amplifier, and the signal stored on magnetic tape, or viewed on a cathode ray oscilloscope, or plotted on a chart plotter or an X-Y plotter. The equipment was used to track the movement of LEDs, which were secured to a lower arch face bow, which was in turn secured to the teeth via a universal joint, and an acrylic clutch. A method was established in a preliminary study, enabling recording of condylar movements in the sagittal plane, and results were presented for four subjects. Subsequently, condylar movements and joint sounds were recorded concurrently for two of these four subjects.

Analog-Digital Conversion↗
PubMed1987

The tooth contact sound as an analogue of the "quality of occlusion".

This study investigated the relationship between the tooth contact sound and its wave pattern, and the interrelationships of the components of the wave pattern. The hypothesis that the tooth contact sound and features of its wave pattern are analogues of the quality of occlusion was also investigated. The sample consisted of 133 subjects. By means of a standardized technique, tooth contact sounds produced during habitual closure were recorded and used to produce wave patterns. Statistical tests were used to determine whether significant relationships existed between selected gnathosonic parameters and aspects of the quality of occlusion that had been assessed by clinical examination. The findings of this study lead to the following conclusions: The measures of wave pattern duration (ALPHDUR and TOTDUR) are significantly related to the amplitude of the wave pattern (or the loudness of the tooth contact sound). Thus, allowance should be made for variations in amplitude when considering the relationship between measures of wave pattern duration and other factors. The measurement of ALPHDUR is independent of the recording equipment used to produce the wave pattern. ALPHDUR may therefore be of use in the comparison of gnathosonic data that have been produced by different recording techniques. ALPHDUR is the wave pattern component that bears the strongest relationship to the categorized tooth contact sound. In some respects, three gnathosonic parameters (tooth contact sound category, ALPHDUR [ADJ], AND AMPL) might be considered to be analogous of the quality of occlusion. Of these, the subjectively assessed tooth contact sound would appear to have some practical application in routine dental practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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↗