12/01/2025
Flexible partials behave very differently from acrylic dentures, and most failures come from overlooking that difference in case planning.
There is no chemical bond between acrylic teeth and the flexible base, so the teeth must be fully surrounded by flexible resin and drilled for mechanical retention. We need about 5 mm of vertical space to do this; if we over-reduce to gain clearance, the base usually survives while the denture teeth fracture or debond.
Flexible partials are tissue borne and the base tends to flex toward the center of the arch, which loads the abutments. On lower arches with few abutments or severe ridge resorption, a metal substructure helps keep the framework rigid, and tall isolated teeth or teeth with heavy buccal undercuts should be avoided as abutments whenever possible.
What criteria are non-negotiable for you before you prescribe a flexible partial, and how are you communicating those limits to your lab team?