Phencyclidine (PCP) was originally developed as an anesthetic, but the adverse side effects prevented its use except as a large animal tranquilizer. PCP acts as both a depress â¦ ant and a hallucinogen,and sometimes as a stimulant. It is abused primarily for its variety of mood-altering effects.
1 An inlay- As the name suggests, this restoration sits inside the tooth.  An onlay- In contrast is bonded on top of the tooth, replacing some or all of the cusps of the tooth.
Introduction. 1  Historically, gold was the material of choice for inlays and onlays. The accuracy and malleability of gold made it an ideal material to restore lost tooth structure and protect weakened cusps destroyed by caries and trauma. 2  The most common indication for inlays or onlays is extensively restored and weakened teeth. The distinction between the two designs is unclear but simply those restorations without cuspal coverage that remain within the body of the tooth would be considered inlays (Figure 12.1) whereas onlays replace tooth tissue including cusps (Figure 12.2).