Calcium hydroxide is a material which has been used for a variety of purposes, since its introduction into dentistry is in the earlier part of 20th century .In its pure form the substance has a high Ph & its dental use relates chiefly to its ability to stimulate mineralization, easy preparation, antibacterial property & its ability to raise acidic Ph to alkaline. A range of products has been formulated with different therapeutic action, the effects of which are partially dependent upon the tissues to which are applied. Calcium hydroxide is considered to be one of the most biocompatible materials in dentistry. This book emphazise on the restorative material used in dentistry that too mainly on calcium hydroxide as its one of the most commonly used material in dentistry.