Case report--hypersensitivity to denture materials.

Hypersensitivity reactions to the commonly used denture base resins are infrequently reported. When they have been reported, most acrylic hypersensitivity reactions have been described as local contact reactions with few reports identifying any significant systemic symptoms. This paper reports a case where the patient suffered extensive systemic symptoms which were strongly linked to denture wear. A variety of alternative dentures of different resin content were constructed over time with varying reactions. The patient was patch-tested and responded with positive reactions to pure dye samples supplied by manufacturers of the resins. She also failed to react to dentures made in a clear acrylic with no dye components. These factors strongly support the hypothesis that the reactions experienced by this patient to some denture resins was the result of the incorporated colouring agents. It is therefore suggested that in cases where a hypersensitivity reaction with systemic manifestations to a denture base resin is suspected, questioning with regard to other reactions to colourants and patch testing for dyestuffs should be considered in addition to the use of a resin with no colouring agents in construction of replacement prostheses.

The interface between United Kingdom, Irish and Australasian college qualifications.

Colleges in different parts of the world fulfil an important role in setting standards and ensuring a high calibre of postgraduate dental education and training. They have evolved to fulfil the requirements of the particular circumstances prevailing in each country. With the changes that are taking place throughout the world and the increasing demands for high quality general and specialist dental care, all of the colleges are modifying their structures and examination formats. In many ways these changes are bringing the colleges more in line with each other. In view of this, there is a need for better communication and closer collaboration between the colleges. In the United Kingdom and Ireland proposals for shorter, more structured training programmes and for more specialist dental care to be provided outside hospitals, together with the influence of European Community law, have resulted in major changes. Among the effects of these changes are a restructuring of training programmes, the development and recognition of new specialties and the reconfiguration of college qualifications.

The effect of chairside relining materials on rat palatal mucosa.

OBJECTIVES: To investigate the effects of denture relining materials on oral mucosa in vivo in a rat model. METHODS: Denture-like appliances covering the palate in Wistar rats were relined with a resilient soft linting material and a hard 'chairside' relining material. The effects on the palatal epithelium were studied by quantitative analysis using computerized planimetry. RESULTS: The relining materials caused an increase in the thickness of the keratinized layer, while not increasing the total epithelial thickness. CONCLUSIONS: Relining materials are not totally without effect on oral mucosa. Further in vivo research is indicated.

The effect of diet on palatal prosthetic coverage in rats.

UNLABELLED: Previous studies have used a rate model for examination of the histopathology of oral candidiasis or mucosal coverage with dental prostheses. These studies have been complicated by the presence of accumulated debris between mucosa and prostheses. OBJECTIVES: The present study was undertaken to develop further the Wistar rat as a suitable animal model on which to study the effects of dental prostheses on oral mucosa. METHODS: The effects of three dietary regimes, used for 7 and 14 days, upon debris accumulation under denture-like appliances and measurable epithelial parameters were analysed by computerised planimetry. RESULTS: Individual variation in animal weights during the study was noted, with some appliance-wearing animals exhibiting a weight gain while others lost weight. A powdered diet used in a paste form gave the least accumulation of debris under appliances and the least differences between appliance wearers and controls. CONCLUSION: The use of the Wistar rat model utilising the past diet described is indicated for future investigation of the effect of prostheses on oral mucosa.

The hinge clasp in removable partial denture design.

As a result of people keeping their teeth longer, modern dentists are encountering more partially dentate patients and difficult restorative problems. It is possible to solve some of the problems caused by the unusual angulations and undercutting when the remaining teeth of partially dentate patients start to drift by using the hinge clasp. The authors describe the types of device available and outline the advantages (and disadvantages) of its use.

Case report: prolonged match chewing: an unusual case of tooth wear.

A case is reported of the diagnosis and clinical management of a patient with an obsessional neurosis resulting in extensive tooth and denture acrylic wear partially caused by prolonged match chewing.

The recording and analysis of EMG and jaw tracking. II. Reproducibility of jaw tracking.

In 10 male and 10 female adults jaw movements and muscle activity were monitored during chewing. Subjects had a Class I occlusion and fluent unrestricted jaw movements; non exhibited signs or symptoms of craniomandibular disorders. Recordings were made on two occasions separated by 2 weeks. Within each recording session the subjects carried out a number of tasks under direction, including eating nuts and gum. The jaw movements were monitored with a Sirognathograph which had been interfaced to a computer for data logging and analysis. A computer program identified each chewing stroke and after scrutiny a data base was constructed of measurements from a subset of 4447 suitable strokes. Mean values of 10 parameters selected to describe jaw movements during chewing were entered into an ANOVA. This indicated that the major contribution to variance was due to the subject from whom the data was recorded. This intersubject variability is well known, but can its separation from the other contributions to the variation within the data be assessed? To provide an estimate of the spread of data the variance for each parameter was calculated, transformed and these values entered into an analysis of variance. All subject differed significantly in their chewing movements from one another. But 15 of the 20 subjects showed a greater degree of consistency than the other five: they exhibited good inter- and intra-recording reproducibility. The food being eaten made a major contribution to the variability. The timing of the chewing strokes was also more consistent than the dimensions of the chewing envelope.

The recording and analysis of EMG and jaw tracking. I. The recording procedure.

A computer-based system is described which records and analyses electromyographic (EMG) signals and tracking data for mandibular movements during function. EMG signals were obtained bilaterally from six muscles and a Sirognathograph monitored the position of the lower incisor teeth in three dimensions. Directed jaw movement tasks by subjects were monitored. These data were continuously sampled at a rate of 1 KHz per channel over an operator controlled period. Analysis of the data was performed off-line following the experiment. Individual chewing cycles associated with masticatory function were identified and the timing and dimensions of each chewing envelope established. Corresponding EMG values were also determined and displays of EMG and jaw movement were plotted on a common time base. An average chewing cycle and correlated EMG activity could also be displayed on a high resolution monitor and plotted for a hard copy to enable a comparison to be made between subjects with and without jaw dysfunction.

The deep overbite: prevention of trauma.

An understanding of the mechanisms by which deep overbite trauma develops will allow interception at an early age of those cases most at risk. Measures may then be taken to prevent progression to the stage where treatment becomes difficult.

Oral mucosa and complete dentures.

The reduction in the epithelial thickness under dentures did not reach the level of significance. The significant reduction in the epithelial morphology indicating a flatter basement membrane would suggest that the epithelium undergoes an adaptive change as a result of surface loading to produce a more uniform epithelium. The degree of keratinization was less and the stratum corneum was thinner in the epithelium under dentures. The complete dentures in these studies seemed to reduce the quantity and quality of the keratin layer. This study has shown that the presence of a denture produced a more regular epithelium with few rete ridges, and a thinner, less highly keratinized stratum corneum.