The science of dental materials involves a study of the composition and properties of materials and the way in which they interact with the environment in which they are placed. The dentist spends much of his professional career handling materials and the success or failure of many forms of treatment depends upon the correct selection of materials possessing adequate properties, combined with careful manipulation. It is no exaggeration to state that the dentist and dental technician have a wider variety of materials at their disposal than any other profession.

Many dental materials are fixed permanently into the patient's mouth or are removed only intermittently for cleaning. Such materials have to withstand the effects of a most hazardous environment. Temperature variations, wide variations in acidity or alkalinity and high stresses all have an effect on the durability of materials.

Selection of dental materials

The process of materials selection should ideally follow a logical sequence involving:

• Analysis of the problem
• Consideration of requirements
• Consideration of available materials and their properties
• Choice of material.

Evaluation of the success or failure of a material may be used to influence future decisions on materials' selection. Many experienced practitioners carry out this sequence with no apparent effort since they are able to call upon a wealth of clinical experience. However, when presented with new or modified materials even the most experienced dentist should return to a more formal type of selection process based on the criteria mentioned.

Evaluation of materials

As the number of available materials increases, it becomes more and more important for the dentist to be protected from unsuitable products or materials which have not been thoroughly evaluated. It should be emphasized, however, that most manufacturers of dental materials operate an extensive quality assurance programmer and materials are thoroughly tested before being released to the general practitioner.

Standard specifications:Many standard specification tests, of both national and international standards organizations, are now available which effectively maintain quality levels for some dental materials. Such specifications normally give details for the testing of certain products, the method of calculating the results of the minimum permissible result which is acceptable.

Laboratory evaluations:Laboratory tests, some of which are used in standard specifications, can be used to indicate the suitability of certain materials. For example, a simple solubility test can indicate the stability of a material in aqueous media – a very important property for filling materials.

Clinical trials:Although laboratory tests can provide important and useful data on materials the ultimate test is the randomized controlled clinical trial and the verdict of practitioners after a period of use in general practice. Many materials produce good results in the laboratory, only to be found lacking when subjected to clinical use.