Fig. 1.

a) Contact 'point' placed above point of maximum convexity of adjacent tooth if achieved (often not). Marginal ridge laterally positioned (to maintain contact) and therefore thin, unsupported and susceptible to fracture. Embrasure flat resulting in a tendency for floss to catch and shred. Non-anatomical 'flat' cervical emergence coupled with high contact point. Tendency to interproximal dead space allowing food impaction. (Wedge position limited by matrix holder). b) Contact area broader. Marginal ridge anatomically positioned and well supported. Embrasure convex resulting in supported anatomical marginal ridge and allowing easy, unimpeded floss access. Anatomical cervical emergence. Papilla fills interproximal area