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Biomedical subjects

A C McLundie

Publications and source records attributed to A C McLundie.

At least 19 recordsLinked to original sources
PubMed1992

Efficacy of a porcelain refinishing system in restoring surface finish after grinding with fine and extra-fine diamond burs.

Commercial porcelain refinishing kits are claimed to restore the surface finish on porcelain after adjustments in circumstances that preclude reglazing. This study investigates the efficacy of one such kit in restoring a Vitadur N porcelain surface finish after grinding with fine (30 microns grit-red band) and extra-fine (15 microns grit-yellow band) high-speed diamond burs. The production of the porcelain test samples, the refinishing procedures, and the refinishing times were standardized throughout. Techniques were selected to simulate clinical practice. Randomly selected examples of surfaces created during refinishing were subjected to scanning electron microscopy, using standard kV and tilt angle settings, and to surface profilometry tracings. Roughness average (Ra) readings were recorded for each test specimen for every surface finish. Ra readings were analyzed statistically using a two-way unbalanced model for analysis of variance. Although refinishing after grinding with a 15 microns grit bur produced surfaces significantly smoother than on specimens previously ground with the 30 microns grit burs, the surfaces remained significantly rougher than when originally glazed. It is concluded that, using the type of kit tested, burs of a grade finer than the existing 15 microns grit yellow band types would be appropriate for porcelain adjustments to permit subsequent refinishing to a surface smoothness comparable to the original glaze.

Aluminum Oxide↗
PubMed1991

Refinishing of porcelain by using a refinishing kit.

Dental porcelain occasionally requires adjustment in circumstances that preclude reglazing. Porcelain refinishing kits are now available commercially. The effects of using one such kit on Vita VMK bonded porcelain was investigated qualitatively and quantitatively using scanning electron microscopic and surface profilometric techniques, respectively. The kit proved incapable of restoring a surface glaze to porcelain adjusted using a fine (red band) diamond bur, but was capable of reducing significantly the surface roughness (Ra) of adjusted porcelain. The importance of distinguishing between the integrity of the surface glaze and measurements of surface roughness is discussed. Confining the application of refinishing procedures to the surface adjusted is important to avoid unnecessary removal of the original surface glaze.

Carbon↗
PubMed1991

Localised palatal tooth surface loss and its treatment with porcelain laminates.

Localised tooth surface loss and subsequent caries in a young patient due to an unusual dietary habit is reported. The treatment and management of such conditions is discussed. Tooth surface loss is a condition seen with increasing frequency, often associated with the retention of the natural dentition into older age. In these older patients, abrasion and attrition tend to predominate as the causative factors but, in younger patients, acid erosion is frequently implicated. The acid involved may be dietary, in the form of carbonated beverages, fruit juices, vinegar or excessive intake of citrus fruits. If not derived from the diet, gastric acid may be the source if the patient has gastric reflux, perhaps associated with an ulcer or, in cases of anorexia nervosa or bulimia, where the patient deliberately induces vomiting and bathes the teeth in acid. There is a preponderance of female patients in the latter categories, although not exclusively so. Sometimes patients develop habits where an acidic substance is held in contact with certain teeth and the erosive process is more localised. This is illustrated in the case quoted by Reuter where grapefruit was held against the palatal surfaces of the upper anterior teeth resulting in enamel loss affecting that area. In all these cases of erosion the affected tooth surface was reported as being hard and shiny, lacking any of the features normally associated with dental caries.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗
PubMed1988

In vitro temperature rises during visible-light curing of a lining material and a posterior composite.

The aim of this study was to measure the rise in temperature during: (i) a single cycle of a curing light unit, (ii) the polymerization of a layer of light-cured lining material, and (iii) the polymerization of a light-cured posterior composite material, and also during combinations of these individual procedures. Experimental work was undertaken in vitro and measurements were made using a thermocouple placed centrally in an insulated PTFE well. Large temperature rises occurred with the use of the curing light alone. The lining material itself did not contribute significantly to the rise in temperature during curing, nor did it provide thermal insulation from the output temperature emitted by the light guide. The presence of a layer of posterior composite reduced the temperature transmitted from the light but the residual temperature rise transmitted was still of such a magnitude as to cause concern regarding possible thermal injury to the pulp.

Calcium Hydroxide↗