Predictable and Precise Tooth Preparation Techniques for Porcelain Laminate Veneers in Complex Cases

Porcelain laminate veneers (PLVs) are one of the most conservative and aesthetic techniques that can be applied when restoring the mouth for improved aesthetics. The longevity of the veneers is good and they are durable, especially if the right indications are in place and the correct techniques are applied (Horn HR, 1983). The fundamental concept in any restorative case is to keep it simple and to concentrate on just one objective – conservation of the sound tooth structure. Where the dentine-enamel junctions (DEJ) meet is very important in terms of the structural strength of the tooth: a complex fusion occurs at the DEJ that can be regarded as a fibre-reinforced bond (Lin CP, Douglas WH, Erlandsen SL, 1993). If preparation is limited to the enamel, there would be insufficient flexibility in the teeth (Magne P, Douglas WH, 1999). If the preparation line passes through the DEJ margin and enters into dentine, while it won’t create a major problem, a number of difficulties may occur if one ends up finishing the preparation on large amounts of dentine. This will not only create complex bonding issues on dentine but will also free the ‘flexing’ factor on the tooth structure (Noack MJ, Roulet J-F, 1987; Van Meerbeek B et al, 1996; Van Meerbeek B et al, 1998). When the tooth starts flexing, a new phenomenon occurs. Firstly, a tooth that has been aggressively prepared has a tendency to bend and the intention is to bond a veneer – a porcelain material – that is very rigid on top of that. Adhesive luting resin will be used in between those two structures, which will try to absorb all the stresses. If the tooth is subject to different occlusal forces and continues to flex, the luting resin at the margin will slowly start to peel off, and the clinician is likely to be faced with micro-leakage or de-lamination. To minimise these effects and problems, precision and care must be taken with case selection and tooth preparation (Belser UC, Magne P, Magne M, 1997). The best situation in which to place veneers is when the teeth are perfectly aligned on the