The material most commonly used for the fabrication of complete dentures is poly (methyl methacrylate) (PMMA). This material is not ideal in every respect and it is the combination of virtues rather than one single desirable property that accounts for its popularity and usage. Despite its popularity in satisfying aesthetic demands it is still far from ideal in fulfilling the mechanical requirements of a prosthesis. The fracture of dentures may be due to the mechanical properties of the acrylic resin or may be due to a multiplicity of factors leading to failure of the denture base material. Generally, there are three routes which have been investigated to improve the impact properties of PMMA: the search for, or development of, an alternative material to PMMA; the chemical modification of PMMA such as by the addition of a rubber graft copolymer; and the reinforcement of PMMA with other materials such as carbon fibres, glass fibres and ultra-high modulus polyethylene. The following review of attempts to improve the mechanical properties of denture base material takes account of papers published during the last 30 years.

The fracture of dentures is an unresolved problem. Despite increasing costs incurred by the nation on the repair of these prostheses, very little has been documented on the type of fracture encountered. This survey was carried out to determine the prevalence of type of fracture by the distribution of questionnaires to three different laboratories. Results obtained showed that 33% of the repairs carried out were due to debonded/detached teeth. Twenty-nine per cent were repairs to midline fractures, more commonly seen in upper complete dentures. The remaining 38% were other types of fractures, the majority of which constituted repairs to upper partial dentures. The latter involved detachment of acrylic resin saddles from the metal in metal based dentures and the fractures of connectors in the all-acrylic resin partial dentures.

Denture cleanliness is essential to prevent malodour, poor aesthetics and the accumulation of plaque/calculus with its deleterious effects on the mucosa. There are a large number of solutions, pastes and powders available for cleaning dentures with a variety of claims for their relative efficacies. Denture cleansers in common use can broadly be divided into those having mechanical or chemical effects. Surveys show that some denture wearers experience difficulty in cleaning their dentures satisfactorily and many wear dirty dentures. Replacement dentures are sometimes necessary due to general deterioration of the denture base material because of the misuse or abuse of a range of approved denture cleaning methods or do-it-yourself cleaning methods such as the use of household bleach. Current popular cleaning methods used among complete and partial denture wearers are discussed and advice is given on recommended methods of cleaning dentures. The results of a survey conducted to assess patients' knowledge of cleaning procedures and methods and materials used are also presented. Respondents used a variety of combinations of cleaning methods. The findings of this survey that a large number of people do not know how to clean their dentures satisfactorily are in agreement with those of previous surveys. Recommendations are given on suitable methods of cleaning both metal and acrylic resin dentures.

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