[Human tooth tissue as dental restorative material]

With the recent development of copy-milling systems for porcelain, it has now become possible to construct fitting restorations from natural human tooth substance. This preliminary study aimed to find out whether it is possible to produce a well fitting Class II inlay from an extracted tooth using a copy-milling machine, so that the inlay produced will have enamel over its whole outer surface and dentine on its inner surface. Two pairs of matching sound extracted permanent molars were used. The molars were matched for mesio-distal size of the tooth crown and the convexity of the approximal surfaces. One tooth of each pair was assigned to be the 'donor' tooth, the other tooth being the 'host'. MO inlay preparations were made in the 'host' teeth. These were restored with the milled 'natural inlays' produced from the 'donor' teeth using the CELAY system. The restored 'host' teeth were sliced and examined using light-microscopy. All specimens showed a good fit and the desired location of enamel and dentine. The milling accuracy was assessed in a second experiment. This experiment showed similar marginal gaps for 'natural inlays' as for ceramic inlays. This study has shown that by using the CELAY milling machine it is possible to 'recycle' extracted teeth for the production of accurate restorations.