When teeth are filled to an extent that any additional filling would either be unsupportable or produce an unsound or non aesthetic outcome a crown is an excellent type of restoration.
It restores the shape, contact areas, appearance and function of the tooth and helps reduce the likelihood of further degradation of the remaining structure.
Crowns, unlike veneers, cover the tooth from all aspects. The procedure for making and fitting them is similar to that of veneers ( impressions, laboratory fabrication and fitting).
The most widely used types of crown nowadays are the metal ceramic and the fully ceramic.
Metal ceramic crowns have an internal metal core that pmvides strength. Porcelain is then bonded to that core and almost completely covers it, giving it the shape and appearance of a perfect tooth.
The fully ceramic crowns use non-metallic, white, central cores. This improves their aesthetic appearance.