post-dam
A pressure-seal ridge built into the posterior border of an upper complete denture, designed to maintain suction and prevent air ingress at the palatal seal area.
Full Definition
The post-dam (posterior palatal seal) is a convex, rounded bead or area of increased pressure built into the posterior border of the maxillary complete denture base. It compresses the pliable soft tissues at the junction of the hard and soft palate, creating a peripheral seal that resists dislodgement of the denture. Dental technicians carve or heat-press the post-dam into the master cast before processing the acrylic base. An inadequately formed post-dam is a common cause of patient complaints regarding upper denture retention. Editors should hyphenate 'post-dam' consistently and not render it as 'postdam' or 'post dam.'
Usage
Usage note: Always hyphenate: 'post-dam.' Do not confuse with 'vibrating line,' which is the anatomical landmark used to determine the posterior extent of the post-dam.
In Context
- "The technician carved the post-dam into the cast using the clinician's marked vibrating line as a guide." — Complete denture laboratory case note
- "Poor retention of the upper denture was attributed to an inadequate post-dam depth at the posterior border." — Prosthodontic review report