The direct technique usually involves placing composite resin on the outside of the tooth using bonding. This method is usually referred to as bonding.
The indirect technique usually involves two appointments because the veneers will be fabricated at a dental laboratory. At the first appointment, the teeth are prepared, impressions taken, and the teeth are given a temporary covering. In two to three weeks the veneers are back from the laboratory, the temporaries are removed and the veneers are bonded to the teeth. The laboratory fabricated veneers are usually made using porcelain or pressed ceramic, and are very aesthetic.
The advantage of veneers versus crowns is that much less tooth material is removed, and the procedure is generally less uncomfortable. Veneers are recommended for teeth that have large fillings or little tooth structure.