primary teeth and composites in permanent teeth. Compomers were seven times as likely to require replacement and composites were seven times as likely to require repair. There are circumstances in which composite serves better than amalgam. For example, when a more conservative preparation would be beneficial, composite is the recommended restorative material. These situations would include small occlusal restorations, in which amalgam would require the removal of more sound tooth structure, as well as in "enamel sites beyond the height of contour". For cosmetic purposes, composite is preferred when a restoration is required on an immediately visible portion of a tooth. Bonded amalgam Dental amalgam does not by itself bond to tooth structure. This was recognized as a shortcoming by early practitioners such as Baldwin. He recommended that the prepared cavity be coated with zinc phosphate cement just prior to filling with amalgam, in order to improve the seal and retention. The practice did not become universally accepted and eventually fell into disuse. Until the 1980s, most amalgam restorations placed worldwide were done without adhesives, although in the 1970s a polycarboxylate-based adhesive liner was formulated specifically for this purpose In the mid-1980s the first reports of the use of resins to bond amalgam to etched tooth structure, much like is done for composite resins, appeared in the literature. Since then, a number of papers have been published on laboratory as well as clinical studies of the technique. For large cavity restorations, features such as pins, slots, holes and grooves can be used for the retention of large amalgam restorations, but they do not reinforce the amalgam or increase its strength. There is no current scientific evidence to justify the extra cost and effort associated with the use of adhesively bonded amalgam restorations in comparison with nonbonded amalgam restorations. In view of the lack of evidence on the additional benefit of adhesively bonding amalgam compared with nonbonded amalgam, it is important that clinicians are mindful of the additional costs that may be incurred. Liners and bases The placement of amalgam restorations can potentially cause sensitivity post-operatively. According to R. Weiner, a protective layer or liner should be placed prior to the placement of amalgam to act as a buffer, helping to reduce sensitivity to the tooth. There are different liners that can be used in dental practices today, many of which contain zinc. Examples of lining materials include zinc oxide eugenol,