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Biomedical subjects

N H Wilson

Publications and source records attributed to N H Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1991

Glove use in clinical practice: a survey of 2000 dentists in England and Wales.

Attitudes to glove wearing by dentists practising within the NHS Regulations were tested by means of a questionnaire distributed to 2000 dentists in England and Wales. The response was 76.5%. The results indicate that 68% of the respondents wore gloves routinely for all patients and procedures, 3% never wore gloves, while the remainder (29%) wore gloves for only selected patients or selected procedures. Reasons given for not wearing gloves routinely included problems of comfort, loss of tactile sensation and the risk of cross-infection, which was perceived to be small. Of the routine glove wearers, only 12% changed gloves between patients, cost being considered to be a factor by 57% of respondents who used gloves for more than one patient. The results indicate that the respondents practising and personal details had an influence on the pattern of glove wearing, with single-handed practitioners and those who graduated before 1979 being less likely to wear gloves routinely. Comparison with the findings of earlier studies of similar type suggest that there is increased awareness in the dental profession of the necessity for glove wearing, but that there is still a need to encourage routine glove use, especially amongst certain groups of GDPs.

Age Factors↗
PubMed1991

Current status and rationale for composite inlays and onlays.

Composite inlay systems, now available to the dental profession, are classified and evaluated. Principle motives for their deployment are the aviodance or reduction of in situ polymerisation shrinkage and the optimisation of restoration contour and adaptation. The criteria for placement of direct or indirect composite inlay restorations are critically reviewed in relation to alternative materials and operative procedures. Dimensions of typical molar and premolar inlay cavities are presented and interim guidelines for inlay cavity design are discussed.

Composite Resins↗
PubMed1991

Performance of occlusin in butt-joint and bevel-edged preparations: five-year results. 4.

The five-year findings of a study to compare the performance of restorations of Occlusin (ICI Dental, Macclesfield, UK) in butt-joint and bevel-edged preparations are reported. Ninety-four (79%) of the restorations originally placed were reviewed at five years, 20 restorations (17%) having failed during the study. Initial analysis of the overall results having failed to reveal any significant differences between the five-year performance of the two types of restorations, the results were combined and analyzed by Chi-square tests and step-wise logistic regression. Chi-square analysis indicated that of the independent variables investigated, size of restoration had the greatest effect on clinical performance. Step-wise logistic regression revealed that only four of the eight dependent variables investigated showed significant predictive relationships with the independent variables, the logistic equation for occlusal marginal adaptation being the most complex. The greatest amount of generalized occlusal surface wear tended to be seen in large-sized Class II restorations in molar teeth, with the main factor influencing wear being found to be the type of restoration (Class I or Class II). It is concluded that the performance of restorations of Occlusin has not been found to differ significantly in butt-joint and bevel-edged preparations after five years in clinical service. Step-wise logistic regression has been found to be a useful tool in the analysis of data obtained during the clinical evaluation of a restorative material.

Adolescent↗
PubMed1991

Five-year findings of a multiclinical trial for a posterior composite.

This paper reports the 5-year findings of a multiclinical (n = 11) trial of a posterior composite restorative. The overall findings, based on data collected from 649 (68 per cent) of the 958 restorations originally included in the study, indicate that the material evaluated satisfies established clinical requirements for posterior composites over periods of up to 5 years. Deviations in the reporting of certain elements of the data appear to have been related to local variations in method.

Acid Etching, Dental↗
PubMed1991

The biosynthesis of the 3-series prostaglandins in rat uterus after alpha-linolenic acid feeding: mass spectroscopy of prostaglandins E and F produced by rat uteri in tissue culture.

The abnormal uterine activity associated with dietary n-3 fatty acids may result from competitive inhibition of PG2 production. Uterine synthesis of 2- and 3-series prostaglandins F(PGF) and E(PGE) was studied using mass spectrophotometry in rats fed diets containing predominantly n-3 fatty acid, n-6 fatty acid, or control pelleted diet. Mass spectra of PGF (Me, TMS and Me, TBDMS derivatives) synthesised by uteri of n-3 fed rats were characterised by 8 ions containing the n-3 double bond, and m.i.d. of the 651/653 ions of PGF-Me, TBDMS indicated PGF3 alpha synthesis (44 +/- 8% and 13 +/- 2% of PGF release by uteri incubated + or -5 micrograms/ul calcium ionophore A23187 respectively). In uteri from the control diet group incubated with ionophore, PGF3 alpha ions were detected and PGF 3 alpha represented 9.5 +/- 1.0% of PGF alpha release. Similarly, analysis of PGE from uteri of n-3 fed rats indicated that PGE3 (16 +/- 6% of PGE) was released in the presence of ionophore A23187. Synthesis of 3-series PG by rat uteri was detected after only 3 weeks of n-3 diet. The capacity to synthesise 3-series PG increased at intracellular calcium concentrations which mimicked cell calcium during decidual autolysis at parturition. These experiments suggest that uterine synthesis of 3-series PG is regulated by the specifity of enzymes incorporating fatty acids, rather than by the cyclooxygenase enzyme.

Animals↗
PubMed1991

Heterogeneity of thromboxane A2 (TP-) receptors: evidence from antagonist but not agonist potency measurements.

1. Thromboxane A2 (TP-) receptors in human, rat and rabbit platelets and in smooth muscle of guinea-pig trachea, rat aorta and rabbit aorta have been characterized by measurement of the potencies of agonists and antagonists having considerable variations in chemical structure. 2. On each washed platelet system, eight prostanoids induced maximal irreversible aggregation (full agonists) and the potency ranking was EP 171 > STA2 > 9,11-azo PGH2 > 9,11-endoxy-10a-homo PGH2 > U-46619 (standard) > PGH2 = 16-p-fluorophenoxy-omega-tetranor PGF2 alpha > 16,16-dimethyl PGF2 alpha. Correlations between the three platelet preparations for both absolute and relative potencies were good. On human platelets, STA2, at concentrations above that required for maximum aggregation, exerted an inhibitory effect which was independent of its interaction with the TP-receptor. 3. Five prostanoids, EP 109, EP 167, EP 204, PTA2 and 16,20-methano PTA2, exhibited partial agonist activity on the platelet and smooth muscle preparations. There was good agreement between absolute potencies on the six preparations; on platelets potency was assessed from shape change measurements, since aggregation, when present, always showed a very shallow concentration-response relationship. The magnitude of the maximum response induced by each compound decreased in the order listed above, to the extent that 16,20-methano PTA2 could be treated as a pure antagonist. 4. With U-46619 as agonist, the pA2 values of seven antagonists were found to be very similar on human and rat platelets. The potency ranking was EP 169 > AH 23848 > EP 092 > ONO 11120 > EP 115 = 16,20-methano PTA2 > BM 13177. There was a similar trend on rabbit platelets but pA2 values were 1.0-1.5 log units smaller; the exception was BM 13177 which had similar affinities. The antagonism produced by EP 169 and AH 23848 was surmountable on rabbit platelets but not on human and rat platelets. 5. None of the antagonists was highly potent on the rabbit aorta (pA2 values < 7.5 by Schild analysis). Affinities on the guinea-pig trachea and the rat aorta were higher and in the same range as those obtained for human and rat platelets. However the correlations of pA2 values between any pair of smooth muscle preparations and between any pair of platelet/smooth muscle preparations were either weak or not significant(P > 0.05). 6. The excellent agreement for both full and partial agonist potencies between the six preparations provides no evidence for TP-receptor subtypes and further suggests that the agonist recognition sites of the TP-receptors could be very similar, if not identical, in nature. In contrast, the different antagonist affinities found in this and other published studies indicate heterogeneity of TP-receptors. However, classification into TP,-, TP2-receptors, etc. on the basis of the limited antagonist data available does not appear appropriate at this time.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Quantitative assessment of a new dental imaging system.

The "Radiovisiography" dental imaging unit (Trophy UK Ltd) is a digital system using an intensifying screen and charge-coupled device in an intra-oral sensor. This paper presents a description of the system and an assessment of the original model in terms of patient dose (relative to film systems), resolution (limiting resolution and modulation transfer function), distortion and image noise (amplitude). The system does offer the possibility of reduced patient exposure and minimal distortion, although resolution and latitude are inferior to standard dental film.

Humans↗
PubMed1991

Radiovisiography for length estimation in root canal treatment: an in-vitro comparison with conventional radiography.

Radiovisiography (RVG) and conventional film (CF) were compared in an in-vitro study for working length estimation of root canals. Hedstrom files (size 15) were placed in the root canals of 60 extracted teeth and the teeth imaged using both CF and RVG. The length of file observed was assessed on CF, RVG and enhanced RVG images. The results indicated that a greater length of file was imaged with CF than with RVG (P less than 0.05). However, enhanced RVG images were not significantly different from CF images. While clinical studies are now indicated to confirm these results, it is suggested that, when utilizing RVG for length estimation in root canal treatment, the enhancement facility should be used.

Dental Pulp Cavity↗
PubMed1991

The history, development and use of interproximal wedges in clinical practice.

Wedges, when correctly selected and applied, can make an important contribution to the initial quality and the longevity of some restorations, and can greatly facilittae a number of clinical procedures. The authors outline the important role of interproximal wedges in restorative dentistry, and, in an historical perspective, describe how the principles elucidated when wedges were first employed in restorative dentistry more than 150 years ago are still applicable today.

Dental Restoration, Permanent↗
PubMed1990

Radiovisiography: an initial evaluation.

An initial evaluation of the latest dental radiographic imaging system, radiovisiography, is reported. Despite limitations in its possible clinical applications and problems inherent within the system design, radiovisiography has been found to be a rapid imaging system capable of producing clinically acceptable periapical images. It is suggested that this system may be of particular value in endodontics and in its present form should be considered as an adjunct rather than as a replacement for conventional intra-oral film. Further studies are now required into recent system modifications which are described.

Adolescent↗
PubMed1990

The incidence of undiagnosed punctures in non-sterile gloves.

This study investigates the incidence of undiagnosed punctures in five types of single and multiple patient use gloves worn by a group of practitioners (n = 6) in general and hospital practice, and provides data on the incidence of undiagnosed punctures in gloves worn on operative and passive hands. Gloves considered to be intact when discarded (n = 510, 85%) were examined for undiagnosed punctures by water inflation. The incidence of undiagnosed punctures varied considerably with glove type (range 3-49%) and among the practitioners (range 9-29%), and some gloves, notably the vinyl type investigated, appeared to be more prone to puncture than the other types of glove. More than 60% of the undiagnosed punctures were in the thumbs and second fingers of the gloves. The incidence of undiagnosed punctures in gloves from operative hands was only slightly greater than that for gloves from passive hands. The gloves intended for multiple patient use were found to have the lowest incidence of undiagnosed punctures. However, the single patient use gloves were typically misused, in that they were worn during the treatment of more than one patient.

Dentistry, Operative↗
PubMed1990

Radiographic inhomogeneity of posterior composites.

A radiographic technique has been devised for determining the structural inhomogeneity between successive specimens fabricated from any given dental composite. This has been applied to nineteen composites currently recommended for the restoration of Class I and Class II cavities. The inhomogeneity data fell within clearly defined bands, with some light-cured posterior composites exhibiting an inhomogeneity parameter of zero. Other hands had average inhomogeneities of 1.5%, 2.5%, 3.8% and 6.8%. The level of inhomogeneity exhibited by a composite system may be an important factor in material selection and in long-term clinical performance.

Chemical Phenomena↗
PubMed1990

Variation in the thickness of the composite lute with an indirect composite inlay system.

The findings of an initial investigation of variations in the thickness of the composite lute around inlays of a fine particle hybrid, light- and secondary-cured indirect composite resin inlay system are reported. The lute thickness varied between 10 microns and 90 microns, and was found to be thinnest and most uniform in the region of occlusal cavosurface margins. Although the marginal adaptation of the inlays investigated was generally considered to be satisfactory, sections of the lute were found to exhibit porosity and to contain a number of voids. It is concluded that whilst the lute thickness and marginal adaptation of composite bonded inlays of the type investigated may be found to be acceptable, further work is desirable to investigate ways to limit porosity and voids in lutes and to form and finish the cavomarginal elements of tooth-coloured inlays in such a way that the limiting layer of luting material may be better protected from the rigors of function in the oral environment.

Composite Resins↗