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Biomedical subjects

A J Qualtrough

Publications and source records attributed to A J Qualtrough.

At least 19 recordsLinked to original sources
PubMed1999

Recent advances in ceramic materials and systems for dental restorations.

The unsurpassed aesthetic and biocompatible qualities of ceramic materials still provide the stimulus to seek to overcome their limitations. Much of the materials research since the mid 1960s has been directed towards producing stronger, reinforced restorations with improved marginal accuracy and, although a new wave of ceramic products appeared in the 1980s, most of the materials currently available are developments derived from ideas established more than 20 years ago. This paper outlines some interesting aspects of recent developments and considers the present state of the art with respect to both materials and techniques.

Biocompatible Materials↗
PubMed1998

Dentin-bonded all-ceramic crowns: current status.

Dentin-bonded all-ceramic crowns employ contemporary techniques to lute the crown to the tooth using a resin luting material and dentin-bonding system. The advantages of these crowns are that they provide good esthetics and fracture resistance and can be used in cases of substantial tooth loss. Their principal disadvantages are that the luting procedure is more time-consuming and that these crowns should not be used where margins are subgingival. Dentin-bonded all-ceramic crowns may be a useful addition to the dentist's armamentarium, but long-term clinical studies are needed to fully assess their performance.

Contraindications↗
PubMed1998

A retrospective evaluation of a series of dentin-bonded ceramic crowns.

OBJECTIVE: This study assessed the clinical performance of dentin-bonded crowns, in which ceramic crowns are bonded to underlying dentin with a resin composite-based luting material and a dentin bonding agent. METHOD AND MATERIALS: Twenty-five patients who had received such restorations more than 1 year previously were recalled for evaluation of their crowns. RESULTS: Sixty dentin-bonded complete-coverage restorations were assessed. Forty-one of the crowns had been placed on incisor teeth. The mean time since placement of the restorations was 2.43 years. Fifty-seven of the 60 restorations were intact. The three failures had resulted from cracks in the restorations, which had not clinically debonded. No secondary caries was detected at the crown margins, and anatomic form was assessed as excellent for 56 crowns. Root canal treatment had been required in one case. Color match was rated very good for 47 crowns. All 25 patients were satisfied with their restorations. CONCLUSION: Dentin-bonded crowns may be found to have a low rate of failure and to provide a high level of patient satisfaction.

Adult↗
PubMed1997

Dentistry in Vietnam.

Although keenly interested and proficient in clinical dentistry, Vietnamese dental practitioners were not benefiting from new concepts in restorative dentistry, shut off to a great degree from the information surge. As senior lecturer and honorary consultant in restorative dentistry at the Turner Dental School, Dr Qualtrough was invited to Vietnam by the dean of the Ho Chi Minh City dental school to give a series of lectures on the theme of advances in restorative dentistry. Here she describes the experience of visiting this country of rapid change.

Dentistry↗
PubMed1997

Ceramics update.

OBJECTIVE: The aim of this paper is to review recent developments in dental ceramics related both to the refinement of existing materials and technologies and to the development of new techniques. DATA SOURCES: The appropriate literature has been reviewed and the relevant information selected for inclusion in this article. CONCLUSION: It is concluded that the main advances are related to developments aimed to overcoming the mechanical shortcomings of ceramic materials, such as their inherent brittleness. Several new systems have been developed, some of which appear to be very promising, but there are, as yet, no data related to the long term performance of restorations by these new techniques.

Ceramics↗
PubMed1997

Undergraduate endodontic teaching in the United Kingdom: an update.

Anecdotal evidence and scientific surveys suggest that the quality of root canal treatment within the General Dental Services is often less than ideal. Six years ago, it was reported that endodontic teaching in the United Kingdom was given a low priority and that the time devoted to the laboratory practice of root canal treatment should be increased. In the following year, the European Endodontic Society (ESE) published guidelines for the teaching of Endodontology and made recommendations as to what should be included in the undergraduate curriculum. Shortly afterwards, the ESE published quality guidelines for endodontic treatment. The aim of this project was to determine the current pattern of undergraduate endodontic teaching within the dental schools of the UK. Data were gathered by questionnaire from all 14 undergraduate dental schools and supplemented with further detailed enquiries where necessary. The results were compared with that reported following an identical survey carried out previously. Although the ESE curriculum guidelines for endodontic teaching provide an overall framework for teaching, the results of this study confirmed that a number of topics were either not included or were covered only briefly. However, the average time devoted to the preclinical instruction of root canal treatment in the first clinical year had increased from 14 to 24 h, with additional time provided in subsequent years by the majority of schools. In most instances, staff teaching endodontology in the UK have no specialist training.

Curriculum↗
PubMed1997

The effect of different ceramic materials on the fracture resistance of dentin-bonded crowns.

This in vitro study investigated the fracture resistance of dentin-bonded crowns constructed from four ceramic materials: feldspathic porcelain, aluminous porcelain, a glass-ceramic core material (Dicor), and a leucite-enriched ceramic (Empress). Forty sound maxillary premolar teeth were chosen and divided at random into four equal groups. The teeth were prepared with a standardized crown minimal preparation. The restored teeth were subjected to compressive loading. When the mode of fracture of the specimens was examined, it was found that four mode V (severe) fractures occurred in the Empress group, compared with none in the aluminous porcelain group and one each in the feldspathic porcelain and Dicor groups. Statistical analysis indicated that the loads required to fracture Dicor specimens were significantly greater than those required to fracture the feldspathic and aluminous porcelain crowns but were not significantly different from the loads achieved by the Empress specimens.

Analysis of Variance↗
PubMed1997

Teaching of all-ceramic restorations in central European dental schools: a survey.

The teaching of all-ceramic restorations in Central European dental schools in the mid 1990s has been surveyed. Based on a 65% response, the findings indicate that the majority of undergraduate (pre-doctoral) students receive instruction in all-ceramic restorations with >75% gaining clinical experience in the use of such restorations prior to graduation. When clinical experience was not received, formal instruction, either in the regular curriculum or in elective studies was generally available. All the schools, with one exception, anticipated that the importance of teaching all-ceramic restorations would increase or at least stay the same. In general, the findings were similar to those reported in studies of the teaching of all-ceramic restorations in North America, Scandinavia, and the UK and Ireland, especially in relation to luting systems, contraindications and finishing instrumentation. However, clinical requirements for all-ceramic restorations in Central European dental schools were more common than in dental schools in North America, Scandinavia and the UK and Ireland.

Clinical Competence↗
PubMed1996

A 3-year clinical evaluation of a porcelain inlay system.

OBJECTIVES: The porcelain inlay technique was described over a century ago, and, although not yet used as a routine restorative procedure, may prove to provide restorations of unsurpassed functional and aesthetic qualities in certain situations. The aim of this study was to investigate the handling properties and clinical characteristics of a porcelain inlay system, to highlight any advantages and disadvantages of the restorations under investigation, and to indicate further studies as considered appropriate. METHODS: Fifty moderate to large-sized Class 1 and Class II restorations of a porcelain inlay system were investigated in premolar and permanent molar teeth of 27 adult patients over a 3-year period using modified United States Public Health codes and criteria. Selected restorations were evaluated indirectly by scanning electron microscopic analysis. RESULTS: There was a high early rate of bulk fracture. By 6 months post-placement there had been a limited deterioration in marginal integrity associated with 20% of the remaining restorations, but this trend was not seen to continue. Patient acceptance was very favourable. CONCLUSIONS: It was concluded that the system under investigation afforded a technique-sensitive method of producing tooth-coloured restorations. Proposals for further work include investigations of the fitting accuracy of indirect tooth-coloured restorations, cavity design modifications and the use of alternative bases and luting agents.

Adolescent↗
PubMed1996

All-ceramic restorations: teaching in UK and Irish dental schools.

The teaching of all-ceramic restorations has been surveyed in the UK and Irish dental schools. Based on a 93% response, the findings indicate that the majority of undergraduate (pre-doctoral) students in UK and Irish dental schools gain clinical experience of all-ceramic restorations as part of their core teaching. While the 14 responding schools provide clinical instruction in all-ceramic crowns and veneers, only 12 schools were found to include instruction in all-ceramic inlays and onlays. A wide range of ceramic systems are taught and there is general conformity in respect of the associated teaching in relation to liners and bases, the selection of impression materials and the use of luting systems, except in conjunction with all-ceramic crowns. The principal contraindications to all-ceramic restorations in undergraduate teaching were found to be poor oral hygiene and parafunctional activity (bruxing/clenching).

Crowns↗
PubMed1996

An evaluation of the fit of porcelain inlays.

The effect of die spacer usage and three different porcelain build up techniques on inlay fit were investigated by impression wash methods and image analysis of sectioned replicas. All inlays were produced on machined cavities. Data from the impression wash technique indicated a mean misfit value of just over 100 microns. Image analysis showed a smaller mean misfit of 40-60 microns. In general, the use of die spacer resulted in a poorer fit and there were no significant differences between methods of porcelain application detected by either method.

Analysis of Variance↗
PubMed1995

The dentine-bonded ceramic crown: an ideal restoration?

The principles used in the bonding of porcelain veneers may also be applied to full-coverage restorations, with such crowns luted using resin-based materials. For these full coverage restorations, dentine bonding agents, preferably of low film thickness, may be used to treat areas of exposed dentine prior to placement. These 'dentine-bonded' all-ceramic crowns may exhibit many favourable characteristics, including those of good aesthetics and peripheral blend with gingival tissues and the potential for placement on conservative preparations which may minimise the risk of pulpal damage. Indications include cases in which conventional crowns require replacement, those in which minimal preparation techniques are appropriate, and those in which there has been tooth surface loss. Contraindications include subgingival margins, extreme occlusal interferences and insufficient tooth substance for bonding. However, the longevity of these restorations is, as yet, unknown, in the absence of long-term clinical data.

Crowns↗
PubMed1995

Dental CAD/CAM: a millstone or a milestone?

The number of dental computer-aided design/computer-aided manufacture (CAD/CAM) systems commercially available is growing. These systems range in complexity and application, from manual copy milling of inlays to full computer-controlled systems with a complex library of tooth forms enabling the automated production of crowns and bridges. All CAD/CAM systems permit the production of restorations at the chairside and, at least in theory, eliminate potential inaccuracies associated with the traditional, multistage production of indirect restorations. Their use also minimizes cross-infection. However, the capital costs of these systems are great and a high throughput of restorations is required in order to achieve financial viability. Long-term clinical studies are required before a final judgement may be made of the use of these relatively new systems.

Computer-Aided Design↗
PubMed1994

Aesthetic inlays: composite or ceramic?

As the aesthetic aspect of dental care becomes increasingly important to patients, the dental practitioner should be aware of the applications and limitations of the various tooth-coloured restorative systems available for the restoration of posterior teeth. Among currently available systems are direct placement resin composites, which may find application in small to medium preparations, and composite or ceramic inlays, which may have wider applications. Similar principles of inlay cavity preparation and restoration placement may be applied to both composite or ceramic systems, with both having the advantage over directly placed composite materials of improved control over anatomic form. Ceramic inlays may provide a high level of wear resistance, but are less simple to construct or repair than composite inlays. While initial clinical trials of composite and ceramic inlays show promise, long-term trials are now required to more fully assess the longevity of these restorations in clinical use.

Bicuspid↗
PubMed1994

A look at dental esthetics.

The surge of interest in the use of tooth-colored restorative materials and systems in recent years has been attributed partly to rapid developments in dental materials science and also to patient demand and operator interest. When overall dental appearance is considered, several factors are of significance, including tooth color, shape, and position; restoration quality; and the general arrangement of the dentition, especially of the anterior teeth. Each factor may be considered individually, but all components together act in concert to produce the final esthetic effect. However, although the clinician must be mindful of the patient's desires for a favorable cosmetic result, materials and techniques must be carefully selected, and restorations should be sufficient to withstand the forces of occlusion and mastication and provide long-term function.

Color↗
PubMed1993

A comparison of two in vitro methods for assessing the fitting accuracy of composite inlays.

Composite inlays were fabricated in standardised cavities cut into aluminum and perspex blocks using a computer controlled milling process. Four materials were used to construct the inlays. These were fabricated using an indirect technique following the manufacturers' recommendations, where applicable. In addition, for one of the composites, the fabrication procedures were modified. The fitting accuracy of the restorations was assessed by taking elastomeric impression wash replicas of the luting space and by examination of sectioned restored units using image analysis. The former method indicated significantly reduced fitting accuracy when either use of die spacer or secondary curing was omitted from restoration construction resulting in incomplete seating. The sectioning technique indicated that more factors appeared to significantly reduce fitting accuracy including bulk packing, alteration in curing time, omission to die spacer and the final polishing procedure. This method also provided more specific information concerning sites of premature contact. One material gave rise to significantly greater film thicknesses using both methods of assessment. No direct correlation was found between the two techniques of fit evaluation but both methods taken together provided complementary information.

Acrylic Resins↗