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Biomedical subjects

R W Wassell

Publications and source records attributed to R W Wassell.

At least 19 recordsLinked to original sources
PubMed2006

Survival of resin-bonded bridgework provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors.

OBJECTIVE: To analyse the clinical performance and factors influencing the survival of resin-bonded bridgework provided for hypodontia patients with missing maxillary lateral incisors, following orthodontic treatment to open, maintain or redistribute the missing tooth space. DESIGN: A retrospective analysis of patients treated at a single centre using case notes with all patients invited for review to corroborate findings. SETTING: Departments of Orthodontics, Child Dental Health and Restorative Dentistry, Newcastle upon Tyne Dental Hospital and School. SUBJECTS AND METHODS: Between 1989-2000, 59 suitable hypodontia patients were identified of whom 45 had complete records. For these patients 73 resin-bonded bridges (RBBs) were provided. Following invitation, 24 patients attended for a review appointment. The survival of the RBBs, grade of operator providing treatment, duration of post-orthodontic retention, the influence of design, presence of pontic contact in static and dynamic excursions, and the effect of habits were assessed. Life table, Kaplan-Meier and Cox regression analysis were carried out for the 73 RBBs with complete records. A separate analysis of the RBBs provided for patients who attended for the invited review did not show a higher failure rate than those patients who did not attend. Therefore both sets of data were combined. RESULTS: Of the 73 RBBs provided, 30 had debonded on at least one occasion (41.1%), six of these debonds were due to trauma (20%). The mean survival time of all the restorations was 59.3 months, with a median survival time of 59 months. Senior members of staff (Consultant, Senior Lecturer or Specialist Trainee) provided most restorations (n = 39) and achieved the highest mean survival of 72.6 months and median survival time of 100+ months. RBBs provided by junior staff and students had significantly lower survival times (p <0.05) compared with senior staff. Risk of failure was 3.9 times greater with junior staff and 2.5 times greater with students (p = 0.01 and p = 0.02, respectively). Analysis of all the other factors investigated showed no statistical difference in survival times or in hazard ratios. Analysis of fixed/fixed versus cantilevered bridges was limited by the number of fixed/fixed bridges (n = 11), and only two cantilevered bridges with multiple abutments were provided; both failed within one month. CONCLUSION: RBBs provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors can for many patients be an acceptable and definitive restoration. Experienced staff achieved the best results, but why this should be was not explained by the individual factors analysed in this study.

Adolescent↗
PubMed2004

Treatment of temporomandibular disorders by stabilising splints in general dental practice: results after initial treatment.

INTRODUCTION: Little is known about how effective general dental practitioners (GDPs) are in treating temporomandibular disorders (TMD). The overall aim of this study was to compare the lower stabilising splint (SS) with a non-occluding control (CS) for the management of TMD in general dental practice. METHOD: A total of 93 TMD patients attending 11 GDPs were randomly allocated to SS or CS. Diagnosis was according to International Headache Society Criteria. Outcome criteria included pain visual analogue scale (VAS), number of tender muscles, aggregate joint tenderness, inter-incisal opening, TMJ clicks and headaches. Splints were fitted one week after baseline and patients were followed-up every three weeks to three months; those not responding to CS after six weeks (< 50% VAS reduction) were crossed over to SS for a further three months. RESULTS: Documentation was returned from nine GDPs for 72 patients (38 for SS, 34 for CS). At six weeks, mean improvements were noted for all outcome criteria, but less so for clicking. There were no significant differences between splints [chi(2)]. Seventeen CS patients had < 50% VAS reduction and were provided with SS in the cross-over group. CS patients with >50% VAS reduction were significantly younger than CS patients who crossed-over (ANOVA, p=0.009) and had significantly less diagnoses of TMJ clicking (chi(2), p<0.05). At the conclusion of the trial 16 patients were referred for specialist management: 11 non-responders (< 50% VAS reduction), one of whom needed occlusal adjustment and five responders also needing occlusal adjustment. CONCLUSIONS: At six weeks SS gave similar relief to CS for all outcome criteria. Patients who crossed-over from CS to SS were more likely to be older and have clicking TMJs. At the end of treatment nine of 11 non-responders to SS had a diagnosis of disc displacement with reduction. However, 80% TMD patients were managed effectively by GDPs using splints for periods of up to five months.

Adult↗
PubMed2002

Crowns and other extra-coronal restorations: resin-bonded metal restorations.

Resin-bonded metal restorations is the final part of the series. Cast metal restorations which rely on adhesion for attachment to teeth are attractive because of their potential to be much more conservative of tooth structure than conventional crowns which rely on preparation features providing macromechanical resistance and retention.

Cementation↗
PubMed2002

Crowns and other extra-coronal restorations: porcelain laminate veneers.

Porcelain veneers are resin-bonded to the underlying tooth and provide a conservative method of improving appearance or modifying contour, without resorting to a full coverage crown. The porcelain laminate veneer is now a frequently prescribed restoration for anterior teeth. The sums spent by the Dental Practice Board on this type of treatment increased from quarter of a million pounds in 1988/89 to over seven million in 1994/95, representing some 113,582 treatments. Since that time the number has stabilised at over 100,000 veneers prescribed each year. The objective of this paper is to give a practical guide on providing these restorations.

Communication↗
PubMed2002

Crowns and other extra-coronal restorations: try-in and cementation of crowns.

Having successfully negotiated the planning, preparation, impression and prescription of your crown, the cementation stage represents the culmination of all your efforts. This stage is not difficult, but a successful outcome needs as much care as the preceding stages. Once a restoration is cemented there is no scope for modification or repeat You have to get it right first time. Decemented crowns often have thick layers of residual cement suggesting problems with either initial seating or cement handling. When the fate of restorations costing hundreds of pounds depends on correct proportioning of cements and the quality of the mix, the value of a well-trained and experienced dental nurse is easy to see. Both dentist and nurse need a working knowledge of the materials they are handling.

Cementation↗
PubMed2002

Crowns and other extra-coronal restorations: impression materials and technique.

Well-fitting indirect restorations can only be made if there are accurate models of the oral tissues available, made from high quality impressions. Waiting for an impression to set may be more stressful for the dentist than the patient. Should the impression need to be repeated there is the embarrassment of having to explain this to the patient, the cost implications of material and time wasted and the aggravation of running late for the next appointment. Yet, if a 'Nelsonian' eye is turned to a defective impression we can only expect a substandard restoration in return.

Crowns↗
PubMed2002

Crowns and other extra-coronal restorations: provisional restorations.

The important role of provisional restorations is often overlooked. This may be because they are left until the end of an appointment when time for construction is short or because they generally do not need to last for long. However, not only can good provisional restorations help produce better final restorations, they can also save a lot of time and expense at subsequent appointments. In fact time spent in their construction will be more than repaid in time saved doing additional procedures, adjustments and remakes later on.

Acrylic Resins↗
PubMed2002

Crowns and other extra-coronal restorations: preparations for full veneer crowns.

Preparations for full veneer crowns is the eighth in the series on crowns and other extra-coronal restorations. Whilst handpiece skills are important, many other factors combine to ensure provision of a satisfactory full veneer crown (also termed 'full coverage crown'). Our aim in writing this article is to consider the principles which influence crown preparation, seasoned with clinical advice our undergraduate and postgraduate students have found useful.

Composite Resins↗
PubMed2002

Crowns and other extra-coronal restorations: cores for teeth with vital pulps.

Cores for teeth with vital pulps is the seventh in the series of crowns and other extra-coronal restorations. A core is defined as 'that part of a preparation for an indirect restoration consisting of restorative material'. This article questions the need for routine pin placement and addresses the following issues--removal of existing restorations, the need for a core, core materials, core retention, and problem solving.

Composite Resins↗
PubMed2002

Crowns and other extra-coronal restorations: aesthetic control.

A pleasing dental appearance is the subjective appreciation of the shade, shape and arrangement of the teeth and their relationship to the gingiva, lips and facial features. Achieving such a pleasing appearance in our patients is not always easy but is critical, not least because our work is effectively on display and this has implications for patients' perceptions of our practice. To be successful, thorough assessment, careful planning and precise clinical execution is required. Every bit as important though, is good communication, both with the dental laboratory and particularly with the patient. In few areas of dentistry can effective communication be as critical as it is here.

Attitude to Health↗
PubMed2002

Crowns and other extra-coronal restorations: occlusal considerations and articulator selection.

For many dentists, occlusion carries an air of mystique. It even seems sometimes that a perverse pleasure is derived in making the whole subject more complicated than it really is. As a clinician, you need to be able to decide what you expect from your proposed restoration, and to identify situations where you may need to alter the existing occlusal scheme. At a fundamental level, you also need to provide the laboratory with appropriate clinical records to ensure that when you fit them, adjustments to the expensively prepared restorations are minimal. This requires a sound understanding of the basics.

Centric Relation↗
PubMed2002

Crowns and extra-coronal restorations: considerations when planning treatment.

Considerations when planning treatment is the third in the series of crowns and other extra-coronal restorations. Articles or chapters on treatment planning in restorative dentistry can make pretty dry reading, often built around a list of factors that might influence your decision-making. In truth though, planning and placing crowns or other extra-coronal restorations cannot be distilled into a series of lists. The decision-making involved requires experience, subtle understanding and a flexible approach, none of which come easily.

Adolescent↗
PubMed2002

Crowns and extra-coronal restorations: materials selection.

Materials selection is the second in the series on crowns and other extra-coronal restorations. Some of us are less than inspired by dental materials science. Nevertheless, many of the things that concern us clinically with crowns and their alternatives are based on material properties. We worry about the strength of the restoration, how well it fits and its aesthetics. We also worry about wear, occlusal control and biocompatibility. Not least of our concerns are dental laboratory charges, which inevitably have to be passed on to the patient.

Biocompatible Materials↗
PubMed2002

Changing patterns and the need for quality.

This series of articles is aimed at anybody who places crowns and other extra-coronal restorations (ie veneers and shims) on individual teeth. We hope that everyone from experienced practitioners to undergraduate students may find something of value. Whoever reads them, we would ask to do so with an open mind. We have tried not to be dogmatic, and the techniques and materials described are not the only ones available, but are the ones which accord with the principles we describe.

Crowns↗
PubMed2000

Direct composite inlays versus conventional composite restorations: 5-year follow-up.

OBJECTIVES: To determine at 5 year follow-up the failure rate, wear rates and other aspects of clinical performance of direct composite inlays compared with conventional composite restorations placed incrementally. METHODS: 100 matched pairs of restorations were originally entered into the trial. Each pair consisted of a direct composite inlay and a conventional composite restoration made from the same material. At 5 years it was possible to recall 65 pairs, of which 54 were complete. Clinical assessments were made using USPHS criteria (indirect measurements of occlusal wear were made using Ivoclar standard dies) and annual bite wing radiographs. RESULTS: There was a trend to more failure of inlays than conventional composites (17.4 c.f. 7.5%) but this was not significant. The clinical performance of both types of restoration was similar and compared favourably with the results of studies of other materials. Secondary decay was diagnosed in only one restoration. Between 3 and 5 years there was some deterioration in cavo-marginal discoloration, marginal adaptation (occlusally) and surface roughness (occlusally). There was no apparent deterioration in colour match, proximal contact, shim stock contacts and Gingival Index. Wear rates of both types of restoration showed no significant difference and were essentially linear with a mean of 33-34 microm per year. CONCLUSIONS: Both inlays and conventional composite restorations complied with ADA specification minimum requirements for posterior composite restorations. In this study the direct inlay technique gave no clinical advantage over conventional, incremental placement.

Adult↗
PubMed1999

Hardness of model dental composites - the effect of filler volume fraction and silanation.

The relationship between structure and mechanical properties for dental composites has often proved difficult to determine due to the use of commercially available materials having a number of differences in composition i.e. different type of resin, different type of filler, etc. This makes a scientific study of any one variable such as filler content difficult if not impossible. In the current study it was the aim to test the hypothesis that hardness measurements of dental composites could be used to monitor the status of the resin-filler interface and to determine the efficacy of any particle silanation process. Ten model composites formulated from a single batch of resin and containing a common type of glass filler were formulated to contain varying amounts of filler. Some materials contained silanated filler, others contained unsilanated filler. Specimens were prepared and stored in water and hardness (Vickers') was determined at 24 h using loads of 50, 100, 200 and 300 g. Composites containing silanated fillers were significantly harder than materials containing unsilanated fillers. For unsilanated products hardness was independent of applied load and in this respect they behaved like homogeneous materials. For composites containing silanated fillers there was a marked increase in measured hardness as applied load was increased. This suggests that the hardness-load profile could be used to monitor the status of the resin-filler interface.

Journal Article↗