Survival characteristics of 771 resin-retained bridges provided at a UK dental teaching hospital.

OBJECTIVE: To analyse the factors affecting the clinical performance and those influencing the survival of resin-retained bridgework provided at a UK dental teaching hospital between 1994 and 2001. DESIGN: A prospective analysis of restorations provided at a single centre using case notes with all patients invited for review to corroborate findings. SETTING: Department of Restorative Dentistry, University of Bristol Dental Hospital and School, Bristol, United Kingdom. SUBJECTS AND METHODS: Between January 1994 and December 2001, data regarding 1,000 consecutive resin-retained bridges provided at Bristol Dental Hospital and School were recorded. Data was available for 805 patients at the time of the study. Following invitation, 621 patients attended for a review appointment. Life table and Kaplan-Meir survival analysis were carried out for all restorations provided. RESULTS: The five-year and ten-year survival rates estimated by the life-table method are 80.8% (95% confidence interval 78.0-83.6%) and 80.4% (95% confidence interval 77.6-83.2%) respectively. The median survival cannot be estimated for this study as the survival probability remains above 80% even at the longest follow-up. Analysis of clinical variables influencing survival revealed that design of the restoration and experience of the operator providing the restoration were significant factors. Resin-retained bridges made with minimal tooth preparation are shown to be superior in terms of longevity than those for which other types of tooth preparation is made. Patient satisfaction with their treatment was high.

BDA special care case mix model.

Routine dental care provided in special care dentistry is complicated by patient specific factors which increase the time taken and costs of treatment. The BDA have developed and conducted a field trial of a case mix tool to measure this complexity. For each episode of care the case mix tool assesses the following on a four point scale: 'ability to communicate', 'ability to cooperate', 'medical status', 'oral risk factors', 'access to oral care' and 'legal and ethical barriers to care'. The tool is reported to be easy to use and captures sufficient detail to discriminate between types of service and special care dentistry provided. It offers potential as a simple to use and clinically relevant source of performance management and commissioning data. This paper describes the model, demonstrates how it is currently being used, and considers future developments in its use.

Three year in vivo investigation to determine the progression of approximal primary carious lesions extending into dentine.

OBJECTIVE: To investigate the proportion of a sample of approximal carious lesions extending up to 1 mm into dentine which progressed over a 3-year period and to examine factors which influenced that progression. DESIGN: Prospective, single centre, clinical study. SETTING: Restorative Clinic at Bristol Dental School, UK. SUBJECTS AND METHODS: Sixty-five adult patients were identified who each had an approximal carious lesion which extended up to 1 mm into the dentine and which were assessed at intervals of up to 36 months. All patients were given appropriate preventive advice. MAIN OUTCOME MEASURES: Progression of the lesions was determined by assessment of sequential bitewing radiographs. RESULTS: 29% of the lesions progressed within 8 months, 56% by 20 months and 69% by 36 months. After 36 months, lesions which extended over 0.5 mm and up to 1 mm into the dentine were significantly more likely to have progressed (92%) compared with shallower lesions which extended up to only 0.5 mm into dentine (50%). CONCLUSIONS: The depth of an approximal dentine lesion was the main clinical marker which related to its progression. It is recommended that operative intervention is considered for approximal lesions which extend deeper than 0.5 mm into the dentine, while preventive treatment and re-assessment may be considered for shallower lesions.

Validity of clinical judgements for the presence of secondary caries associated with defective amalgam restorations.

Eighty patients were selected, who were each deemed to require the replacement of a defective amalgam restoration. The patients had a mean age of 36.7 years and were dentally fit on average 40 months previously. The main reasons given for the replacement of the defective restorations were perceived radiographic secondary caries (31%), fracture of the restoration (20%), marginal defect (17%), and perceived secondary caries observed clinically (14%). Following the removal of the restorations, a highly significant relationship was found between the consistency and colour of the underlying dentine (P < 0.00001). Soft dentine was found underlying 36 (88%) of the 41 defective amalgam restorations which were diagnosed as having caries associated with them. However, hard dentine was found underlying only 19 (49%) of the 39 teeth where no caries had been diagnosed. The presence of soft dentine where not anticipated was mainly in association with fractured restorations (11 out of 16). Younger patients were more likely to have soft dentine underlying their defective amalgam restorations than older patients (P = 0.005). No relationship was found between the presence of corrosion products on the cavity walls associated with defects and the consistency of the underlying dentine.

Clinical aspects of occlusion: 2. The reorganized approach.

This is the second of two articles which aims to familiarize the reader with essential occlusal principles and terminology and to give some guidelines as to which cases are suitable for crown and bridgework. The first article covered occlusal terminology and the conformative approach to crown and bridgework, the second describes the reorganized approach. In both articles, there are illustrated, clinical cases which demonstrate and overcome some of the occlusal problems encountered.

Clinical aspects of occlusion: 1. Occlusal terminology and the conformative approach.

This two-part series aims to familiarize the reader with essential occlusal principles and terminology and to give some guidelines as to which cases are suitable for crown and bridgework. The first article covers occlusal terminology and the conformative approach, whilst the second will describe the reorganized approach. Both papers contain clinical cases which demonstrate how to overcome some of the occlusal problems encountered in this area.

The relationship between failure and design in conventional bridgework from general dental practice.

A total of 142 failed bridges constructed in general dental practice were assessed for design factors that might relate to failure. The overall mean age of the bridges at failure was 6.2 years; anterior and complex bridgework had a mean age of about 5 years, compared with 7.5 years for posterior bridges. The lifespan of the bridgework was significantly correlated with the number of retainers but not with the number of units. Bridges with one or two retainers had an average lifespan of just over 7 years, whilst those with three or more retainers had been in service for, on average, only 4 years. The practical difficulties of constructing multi-abutment bridgework could account for this difference. One hundred and ninety-one of the 346 retainers were porcelain bonded to semi non-precious metal crowns, and had a mean lifespan of 3.7 years, whilst those that were gold based lasted at least twice as long. Post crowns as retainers survived on average for 6.2 years.

Failed conventional bridge work from general dental practice: clinical aspects and treatment needs of 142 cases.

The reasons for failure of 142 bridges in 130 patients from general dental practice seen at the Bristol Dental Hospital from 1981 to 1986 were assessed. Most patients were either self-referred or sent by a dentist who had not made the bridge. The mean age of the bridges at failure was 6.2 years. The main single reasons for failure were secondary caries or apical pathology, but many bridges failed as a result of factors related to design and structure. Bridges of porcelain fused to gold or gold faced with acrylic lasted twice as long as those of porcelain fused to alloys. There was no correlation between the age of the patient at bridge placement and years of service. Eighteen per cent of the bridges were repaired, recemented or rescued by endodontics alone; 61% were replaced by a new bridge, and the remainder required a removable prosthesis.

Changing perceptions of the requirements of cavity preparations.

Perceptions of the requirements of cavity preparations have changed over the years. These have had a significant effect on undergraduate teaching at the University of Bristol Dental School, an explanation of which may help general dental practitioners in their quest for information on this important aspect of dental practice. A method is described for teaching undergraduate dental students cavity preparation in caries-free teeth, based upon the position, shape and extent of imaginary carious lesions. Scale diagrams of teeth are used, on which imaginary caries at the amelodentinal junction has been marked. The students are instructed to apply the principles of cavity preparation to equivalent, but caries-free, teeth in the laboratory. 'Outline forms' and other predetermined cavity shapes are not taught. Dental practitioners may find it appropriate to apply similar thinking to cavities they prepare in everyday practice, in an endeavour to avoid the unnecessary removal of tooth tissue that would be better retained.

Cytoplasmic granular change of Sertoli cells in two cases of Sertoli-cell-only syndrome.

The testicular biopsy specimens of two cases of Sertoli-cell-only syndrome are described, in which some of the Sertoli cells are filled with coarse cytoplasmic eosinophilic granules. Histochemical stains suggest that the granules contain glycocompounds and phospholipids. On electron microscopy, the granules prove to be densely populated secondary lysosomes, containing membrane fragments, phospholipid-like materials, and other amorphous masses of various densities. Whether the excessive secondary lysosomes arise as a result of some metabolic block in the Sertoli cells, or merely represent autophagy in response to the absence of germ cells, cannot be determined. A search of the literature indicates that this is the first instance, to our knowledge, in which such changes are reported in Sertoli-cell-only syndrome.