EVectiveness bulletin What type of filling? Best practice in dental restorations

Dental caries (tooth decay) is one of the most common diseases, with approximately 80% of the population in developed countries having experienced the condition. If decay has not been prevented cavities develop. To prevent considerable pain and tooth loss it may be necessary to remove the diseased tissues and restore the cavities (a filling). Restorations have a limited lifespan and, once a tooth is restored, the filling is likely to be replaced several times in the patient’s lifetime. Studies in the UK suggest that much of restorative dentistry is replacement of existing restorations, accounting for around 60% of all restorative work. Similar figures have been found in other parts of Europe, 4 and the USA. (Quality in Health Care 1999;8:202–207) There is a large choice of materials which can be used for fillings. Many are introduced into the market place and used on patients with limited evidence that they are more eVective or robust than existing materials. Consequently, one of the key questions is, all other things being equal, what type of filling is best? This paper summarises the results of a systematic review of the relative longevity and cost eVectiveness of routine intracoronal dental restorations, which formed the basis of a recent issue of EVective Health Care. The reasons for replacing a restoration are numerous and vary with tooth type and restorative material. Once inserted, restorations may fail at variable rates due to various “objective” factors aVecting both the failure of the filling material and further decay of the tooth around the filling. These factors include the characteristics of the filling material and eVect modifiers related to operator skill and technique, patients’ dental characteristics, and the environment around the tooth. The decision to replace a restoration is also influenced by more subjective factors such as dentists’ interpretation of the restoration’s condition and the health of the tooth, the criteria used to define failure, and patient demand. These decisions are subject to much variation. 10 A lack of standardisation exists, and no generally agreed criteria are used to decide when a restoration requires replacement. Types of restoration Tooth restorations may be classified as intracoronal, when they are placed within a cavity prepared in the crown of a tooth, or extracoronal, when they are placed around (outside) the tooth as in the case of a crown. Intracoronal restorations are usually placed directly into the tooth cavity and normally consist of a mouldable material that sets and becomes rigid; the material is retained by the surrounding walls of the remaining tooth tissue. An alternative intracoronal restoration uses an indirect technique; here an impression of the cavity is taken and a laboratory constructed inlay is produced and subsequently cemented into the prepared cavity. The materials currently used to restore intracoronal preparations are: dental amalgam, composite resins, glass ionomer cements, resin modified glass ionomer cements, compomers and cermets, cast gold, and other alloys inlays and porcelain (box 1).