English

Abstract

A unique concern of a removable denture when compared to others is retention. Retention is the ability of the prosthesis to resist the movement of denture away from the supporting tissues/teeth. The component of removable denture which provides retention is called as direct retainer. 1,3,4 A direct retainer can be either an extracoronal or intracoronal retainer. Extracoronal direct retainer uses mechanical resistance to displacement through components placed on external surface of abutment teeth. Intracoronal retainer is either cast or attached totally within the restored natural contours of an abutment tooth.1 One of the main drawbacks of extracoronal retainers used in partial dentures is visibility. Many patients find themselves in an aesthetically compromised state when these retainers are placed on teeth in visible area. Precision attachments provide solution for this problem. Also, precision attachments provide better vertical support and better stimulation to the underlying tissue through intermittent vertical massage. 1,9 Although the history of intracoronal retainers goes back to 5 th and 4 th centuries BC, technically more sound developments began in early 20 th century AD, with Dr. Herman E. S. Chayes formulating the principle of internal attachment in 1906. Since then precision attachments are playing an important role in removable and fixed partial denture, conventional and implant supported overdenture. 9