Complete Dentures: Retention, Recording, and Occlusion
Core concepts
A complete denture replaces the entire dentition and its supporting hard and soft tissues, so success depends on three pillars: retention (resistance to vertical dislodgement, from adhesion, cohesion, atmospheric pressure and an intact border seal), stability (resistance to horizontal and rotational forces) and support (resistance to seating forces, from the denture-bearing area). You must be able to describe the impression sequence: primary irreversible hydrocolloid, border molding in a custom tray, then a wash of light-bodied material to capture the peripheral seal. The posterior palatal seal sits at the vibrating line and must not extend onto the soft palate beyond the fovea palatini; overextension here causes gagging, while underextension loses the seal. Jaw relation records establish centric relation (CR) at an acceptable vertical dimension of occlusion (VDO), leaving 2–4 mm of freeway space. Because denture wearers lack periodontal proprioception, occlusion is designed as bilateral balanced occlusion in eccentric positions, usually with reduced or absent incisal guidance to limit tipping forces.
Traps
Questions blur CR with maximum intercuspation, or suggest raising VDO for esthetics without considering freeway space. Another favorite: blaming a loose maxillary denture on "insufficient suction" when the real fault is a lost posterior palatal seal or an unrelieved frenal notch. Christensen phenomenon - a posterior open bite on protrusion when VDO is too great - is a common distractor.
Rule of thumb
If the denture lifts on opening, check the posterior palatal seal and border extension; if it lifts on closing, check occlusal interference and excessive VDO. Verify any CR record by repeating it - a record the patient can tap into reproducibly beats a single tracing.
Worked example
A patient returns with a sore spot over the mylohyoid ridge and a denture that rocks on the left. Rocking suggests a unilateral premature contact: adjust occlusion in CR first, then use pressure-indicating paste to refine the border rather than grinding the intaglio blindly.