Large facial defects are difficult to restore prosthetically due to lack of anatomic undercuts, limited means of retention, mobility of soft tissues and weight of prosthesis. Retention has always been a problem in maxillofacial prosthodontics. Increase in retention improves comfort as well as confidence and quality of life of the patient. There are various methods for gaining retention, stabilization and immobilization. This book is intended to cover a complete detailed description and review of the retentive measures used for oral and maxillofacial prostheses.