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Biomedical subjects

R J Elderton

Publications and source records attributed to R J Elderton.

At least 19 recordsLinked to original sources
PubMed1998

Inhibition of demineralization in vitro around amalgam restorations.

OBJECTIVE: The purpose of this in vitro study was to evaluate some forms of preventing or avoiding demineralization within enamel cavity walls adjacent to amalgam restorations. METHODS AND MATERIALS: Third molar teeth were sectioned to obtain 72 specimens, divided into one control and five experimental groups: amalgam only; varnish plus amalgam; acidulated phosphate fluoride plus amalgam; adhesive amalgam; glass-ionomer cement plus amalgam; control (amalgam only, not subjected to a demineralization challenge). The experimental groups were subjected to PH and thermal cycling and then submitted to enamel hardness determinations. RESULTS: Significant differences between the treatment groups revealed that the bonded amalgam technique offered the best resistance to demineralization. The use of cavity varnish resulted in greater mineral loss than amalgam placed alone. CONCLUSION: The use of an adhesive system, glass-ionomer cement, or acidulated phosphate fluoride under amalgam restorations may interfere with development of secondary caries.

Acidulated Phosphate Fluoride↗
PubMed1997

Changing the course of dental education to meet future requirements.

Dental education is burdened by outdated curricula, which are based on yesteryear's concepts. As a result, caries and restored teeth are still largely "managed" by traditional operative dentistry. This leads into a repeat restoration cycle, which fails to address the fundamental bacterial nature of caries, the primary raison d'être for this form of therapy. At the same time, many fundamental changes have taken place in the parameters that affect, or should affect, dental care. These range from an improved scientific understanding of the caries process, to a realization by society that maintaining oral health through regular preventive dental care, as opposed to ongoing restorative dental procedures, is a worthwhile and achievable goal. Dental education needs to rise proactively to the challenges presented by the new parameters of modern dental care, or it will be forced to make changes from a defensive position. The ultimate change, which most readers would not consider trivial, would be the closure of one or more of Canada's 10 dental schools.

Canada↗
PubMed1996

Treating restorative dentistry to health.

The concepts that underpin much of dental practice need refocusing so as to accommodate the many scientific advances that have been made in recent years in understanding oral disease processes and their management. "Treatment' should come to mean what it says, namely the curing of diseases- and much of this can only be accomplished by non-invasive means. Restorative procedures should be seen simply as prosthetic, making up for lost tissues. The sequence of events with respect to caries should usually be diagnosis followed by treatment, and then the option of restoration if appropriate. In order to achieve this state of affairs for the whole population, I believe it will be necessary to stream dental undergraduates so that, while a portion learn restorative techniques and become licensed to practise them, the remainder concentrate on the non-restorative aspects of dentistry, having a special emphasis on the prevention and non-invasive "treatment' of oral and dental diseases, including caries, on a community scale. This latter group of dentists would not be licensed to undertake restorative procedures.

Dental Care↗
PubMed1994

Biological and clinical investigations of a glass ionomer base material.

OBJECTIVES: The purpose of this study was to investigate the biological properties of a new glass ionomer base material containing strontium glass. METHODS: The glass ionomer base material (Base Line, De Trey Dentsply) was tested for cytotoxicity using a standard agar diffusion test, for its effect upon the pulp in subhuman primates, and in a clinical study as base beneath both composite fillings and amalgam fillings. RESULTS: The material showed a cytotoxicity pattern similar to reference materials, a zinc phosphate cement and a reference glass ionomer base material, which are used successfully in clinical applications. With the pulp/dentin usage test in subhuman primates, there were no statistically significant differences between the experimental glass ionomer base material and the negative control group if bacterial contamination of the cavity floor or direct contact with the pulp was avoided. The results of the clinical study also indicated no pulp damage after one year. SIGNIFICANCE: The experimental glass ionomer base material proved to be acceptable both biologically and clinically.

Analysis of Variance↗
PubMed1994

The effect of changes in caries prevalence on dental education.

While rising levels of dental caries were primarily responsible for the growth in dental schools in developed countries, the recent decline in caries prevalence has not resulted in a major decline in dental education. Indeed, the reduction in caries prevalence has had very little influence upon a group of major changes that arguably should have had a marked effect upon dental education in recent years, but which have failed so to do. These include a quantum leap in applying the scientific basis of caries management, focused down to the teaching of minimally invasive restorative care within a context of risk assessment and maximum non-invasive care where appropriate. A possible way forward in accelerating the necessary changes in dental practice would be for only a proportion of dental undergraduates in the future to be taught practical restorative procedures, leaving the remainder to concentrate on diagnostic and non-invasive care without the distraction of possible restorative treatment.

Adult↗
PubMed1993

Bonded amalgam restorations: a comparative study of glass-ionomer and resin adhesives.

This study assessed the effectiveness of a glass-ionomer liner/base (Vitrebond) and two adhesive resins (Amalgambond and Panavia Ex) in bonding amalgam to enamel/dentine cavities in vitro. Restorations placed without any intermediary, or with varnish, served for comparison purposes. Standardised unretentive cavities on the buccal sides of a total of 78 extracted human molar teeth were prepared to receive the restorations. After application of the adhesive materials (without light curing the Vitrebond), the cavities were filled with amalgam (Dispersalloy). Each specimen was stored for 24 hours in distilled water at 37 degrees C. The amalgam restorations were then pulled from the cavities using an Instron machine and the retentive strength values were recorded. The results showed that any of the three adhesive intermediary agents substantially enhanced the retention of the amalgam restorations. The Vitrebond specimens had the highest mean retentive strength value (133 N), followed by Amalgambond (18% lower) and Panavia Ex (38% lower); the difference between the value for the Vitrebond specimens and that for the Panavia Ex specimens was statistically significant. The Vitrebond specimens failed due to gross enamel fractures and a cohesive failure of the glass-ionomer layer. The Amalgambond specimens failed at the resin/amalgam interface, while the Panavia Ex specimens showed enamel fractures and failure at the resin/dentine interface. It appears that Vitrebond has the potential for being an effective amalgam adhesive in vivo.

Analysis of Variance↗
PubMed1993

Effects of low fluoride concentrations on formation of caries-like lesions in human enamel in a sequential-transfer bacterial system.

Human enamel surfaces were exposed to sequential batch cultures of Streptococcus mutans NCTC 10832 in a sucrose-rich medium containing 0-5 mg/l added fluoride (F). In 10-day experiments, subsurface lesion formation was partly inhibited by 1 mg/l F and completely by 2 and 5 mg/l F, but small lesions formed in 2 mg/l F in 21-day experiments. Analysis of the spent media, together with analogous, bacteria-free experiments, suggested that lesion inhibition involved two main effects. First, inhibition of bacterial acid production reduced the pH fall, resulting in reduced undersaturation with respect to hydroxyapatite and consequently reduced rate of demineralization. Secondly, interaction of F with enamel mineral resulted in a small increase in reprecipitation during periods of supersaturation and a much larger reduction in demineralization during periods of undersaturation. It is concluded that, at low F concentrations, inhibition of bacterial acid production is a major factor in lesion inhibition, which may contribute significantly to caries prevention in vivo where plaque fluid F levels are raised by frequent topical applications.

Apatites↗
PubMed1993

Overtreatment with restorative dentistry: when to intervene?

Traditional restorative dental treatment has many shortcomings and has not been shown to be an effective method for managing caries. In spite of this, many dentists continue to be powered by an aggressive restorative approach which may result in unnecessary treatment and which must now be seen as inappropriate. There is a pressing need for a greater understanding as to the precise criteria that dictate the need for both non-invasive (reversible) preventive measures and invasive (irreversible) restorative treatment. This paper examines these criteria and provides decision trees with respect to the clinical management of carious lesions and teeth with existing restorations, showing when, and what type of, intervention is required. The assessment and management of fissured tooth surfaces receives special attention. It is demonstrated that while many clinical situations warrant clinical intervention, often this should be entirely preventive and of a non-invasive type.

Decision Trees↗
PubMed1992

Bond strengths of dentine bonding agents to dentine.

This study assessed comparatively the tensile bond strengths to dentine of four resin dentine bonding agents. Flat surfaces were produced in the occlusal dentine of human third molars, finished with 600-grit paper and prepared for bonding to Silux Plus composite with Gluma, Prisma Universal Bond 2, Scotchbond 2 and Tenure. After 24 hours in water and 250 thermal cycles, the specimens were loaded in tension to failure on an Instron machine. There were 20 specimens in each test group. An analysis of variance and Duncan's test showed that the bond strengths of Scotchbond 2 (22.8 +/- 7.2 MPa) and Prisma Universal Bond 2 (20.1 +/- 7.8 MPa) were similar but significantly higher than those of Tenure (14.3 +/- 5.3 MPa) or Gluma (12.3 +/- 6.4 MPa). A Weibull analysis confirmed the superiority of Scotchbond 2 and Prisma Universal Bond 2. Scotchbond 2 and Prisma Universal Bond 2 specimens failed either in an adhesive-cohesive mode, or cohesively through the composite or the dentine. It was concluded that Scotchbond 2 and Prisma Universal Bond 2 are effective and are the dentine bonding agents of choice.

Composite Resins↗
PubMed1992

Iatrogenesis in the treatment of dental caries.

Traditional restorative dental treatment has many shortcomings and has not been shown to be an effective method for managing caries. In spite of this, many dentists continue to be powered by an aggressive restorative approach which, in the light of changing "rules" of operative dentistry, must now be seen as inappropriate and as a form of iatrogenesis. Many things have changed in recent years, including: the prevalence of caries; understanding of the science of the caries process; a fuller appreciation of the problems inherent in restoring teeth; cavity design; restorative materials; and the demands of patients. Dental practice needs to change very dramatically if iatrogenesis is truly to be reduced to a minimum and dentistry is to provide the sort of preventive-based care the modern consumer is increasingly realising makes most sense.

Dental Caries↗
PubMed1991

Resin-to-enamel bonds: effect of cleaning the enamel surface with prophylaxis pastes containing fluoride or oil.

A thorough dental prophylaxis before acid-etching of enamel is often recommended. In the method most commonly used, a slurry of pumice is applied with a rubber cup. Oil-based and fluoride-containing prophylaxis pastes are not generally recommended because of fears that they might hinder the etching process. This study assessed the 24-hour shear strength of resin (Scotchbond 2/Silux Plus) bonded to etched enamel which had been cleaned before acid-etching with a slowly rotating rubber cup loaded with: (1) wet pumice; (2) fluoride-containing non-oil-based pastes (En-De-Kay fluoride paste, Nupro fluoride paste); (3) non-fluoride oil-based paste (Kemdent); and (4) nonfluoride non-oil-based pastes (Nupro, Orapol). The bond strength values obtained after using the various cleaning agents were similar. Furthermore, bond failure in all the test groups was of the cohesive type. It therefore appears that prophylaxis pastes containing fluoride or oil may be used to clean the enamel before acid-etching.

Acid Etching, Dental↗
PubMed1991

Bonding dental amalgam to a light-curing glass-ionomer liner/base.

At a time when amalgam is used widely, yet when the criteria for its use are still evolving, the incorporation of an element of adhesive bonding between the amalgam and the base material may come into greater prominence and aid the general move towards more conservative new or replacement cavity preparations. This study assessed the 24-hour tensile bond strength of amalgam (Dispersalloy) to a light-curing glass-ionomer liner/base (Vitrabond), using Scotchbond dual cure, uncured Vitrabond or Vitrabond liquid as intermediaries. Using the Weibull distribution function, it was found that uncured Vitrabond was a better intermediary than Scotchbond or Vitrabond liquid. The bond strengths obtained with uncured Vitrabond intermediary were of the same order as those which can be expected between a glass-ionomer cement and dentine. This suggests scope for developing techniques for bonding amalgam to parts of cavity preparations.

Dental Alloys↗
PubMed1991

Bonding of a light-curing glass-ionomer cement to dental amalgam.

In the clinical situation, the need may arise for placement of a glass-ionomer cement over an existing amalgam restoration. This study assessed the tensile bond strength of a recently developed light-curing glass ionomer (Vitrabond) to dental amalgam (Dispersalloy), with and without the use of Scotchbond dual cure as an intermediary. Amalgam adherend specimens were prepared, then aged in water at 37 degrees C for seven days. Immediately before being bonded, the amalgam surfaces were finished flat on 600-grit paper. Forty specimens were used for bonding in this condition, and another 40 were covered with a thin layer of Scotchbond, which was light-cured for 10 s. The glass-ionomer was applied to the adherend surface in two increments, each light-cured for 30 s. After being bonded, half the specimens were stored in water at 37 degrees C, while half were stored in an environment of 95 +/- 5% RH at 37 degrees C. The 24-hour tensile bond strengths, in MPa, were: for specimens stored in water, without Scotchbond 8.4 +/- 1.2, with Scotchbond 4.7 +/- 1.3%; and for specimens stored in 95 +/- 5% RH, without Scotchbond 9.2 +/- 2.1, with Scotchbond 4.6 +/- 1.5. The data were further analyzed by the Weibull distribution function. It was concluded that a strong reliable bond can be achieved between Vitrabond and set Dispersalloy, and that the use of Scotchbond as an intermediary is contra-indicated.

Contraindications↗
PubMed1991

Technical note: resin-to-metal bonds mediated by adhesion promoters.

This study aimed to establish whether the bonding between a composite cement (Comspan Opaque) and grit-blasted nickel-chromium alloy (Biobond Plus) could be enhanced by pre-treatment of the alloy surface with adhesion promoters. Six groups of metal adherends, of ten specimens each, were prepared. The specimens in each group were finished flat and blasted with 50 microns alumina. The first group was used without further treatment of the metal surface. A second group was electrolytically etched. Each of the remaining four groups was treated with an adhesion promoter. The resin cement was bonded to the adherend and, after 24 h in water at 37 degrees C, the tensile bond strengths were determined. ANOVA and the Scheffé test at the 0.05 level showed that Scotchbond dual-cure dental adhesive enhanced the resin-to-metal bond significantly and produced a mean bond strength value (30.9 MPa) higher than that obtained with electrolytic etching (22.7 MPa) or grit-blasting (14.6 MPa). This would appear to be of considerable significance. The metal primers, ABC primer and GoldLink, and the ceramic primer, Scotchprime, were much less effective than Scotchbond dual-cure.

Adhesives↗
PubMed1991

Preventive versus restorative management of dental caries.

Dental caries is a preventable disease and established lesions can become arrested. Traditional restorative treatment has many shortcomings and there is a need for dentists to manage carious lesions as far as possible by preventive means. Patients should be motivated to accept responsibility for changing the environment of their teeth so that the calcium and phosphate balance favours remineralization, but the dentist should still make use of therapeutic fissure sealants or place restorations when necessary. As long as dentists continue to be obsessed with a restorative approach to caries management, the repeat restoration cycle with its accompanying escalating costs seems likely to continue. The implications of this change in philosophy are enormous, for areas of the world where oral care services are comprehensive, and for countries like South Africa where services are still being developed in some regions.

Dental Caries↗