Mind the Crown Margins

Metal free ceramic restorations have increased in demand due to their superior esthetics and more resemblance to the natural teeth, more so now that metal-free biocompatible options are preferred. Although porcelain fused to metal crowns are also used owing to less tooth structure loss in their preparation, the metal portion shows through the marginal area giving a blue-gray, cyanotic appearance to the tissue. Margins are one of the most important components in the success of a ceramic restoration. Essential prerequisites for the clinical success of an all-ceramic restoration includes good esthetics, a high resistance to fracture and perfect marginal fit. A poor marginal design or one that is not prepared well may be a source of plaque accumulation, other than being esthetically unpleasing. Different marginal designs have been proposed and the most acceptable ones for all-ceramic restorations are either the rounded shoulder or the large chamfer margin. A major part of the current literature and research done on this subject falls into two broad categories that are affected by the type of marginal finish line – marginal fit and fracture resistance.