A mechanical device designed to hold a matrix band in position on the tooth. There are many different designs in current use. The ivory retainer has claws which engage in holes strategically placed in the band to allow for teeth of different circumference; it can be used for posterior teeth with only one missing proximal wall. The Siqveland retainer is self-adjusting to provide a narrower circumference at the gingival area of a cavity preparation and can be used for preparations with more than one missing proximal wall. It is available in two sizes to take either narrow or broad bands. Tofflemire retainers utilize pre-shaped annular bands held by screw tension; a knurled nut is rotated to tighten the band round the tooth; the band can be removed before the retainer is released separately; Tofflemire bands can also be used for preparations with more than one missing wall.
A circumferential retainer can be tightened to give a band with a narrower circumference in the gingival area and wider circumference at the occlusal. Contact ring matrix retainers (trade names: BiTine, Contact matrix, Composi-Tight) have been developed for use with sectional matrices to provide tooth wedging and reduce the need for interproximal wedging.
Types of matrix retainer