[Margin's location of the full coverage crowns].

The margin's location of full coverage crowns is one of the most important factor susceptible to failure both biologically and mechanically. Most of the investigative proof shows that supragingival margins are kinder to gingivae than are subgingival margins. However clinical practice teaches and shows that supragingival margins are not always possible. For this reason in this study authors suggested intrasulcular margins. Of course all the factors of successful preparation is taken into under serious consideration. The related literature is also reviewed and the concept of "biological width" is presented.