complete dentures retention and stability Flashcards
(32 cards)
define retention
resistance of a denture to vertical movements away from the tissues
define stability
resistance of a denture to displacement by functional forces
what is interfacial surface tension?
fluid between 2 rigid materials
explain interfacial surface tension in a denture
Border of the denture is surrounded by air and saliva is between the denture and the soft tissues giving interfacial surface retention
the strength of interfacial surface tension is determined by what?
the ability of the fluid to wet the 2 materials
watery saliva or mucous saliva provides better interfacial surface strength?
watery saliva as better wettability
what is interfacial viscous tension?
the force holding two plates together that is due to the viscosity of the liquid
what is the relationship between viscosity and interfacial viscous tension?
as viscosity increases interfacial viscous tension increases
what is the relationship between interfacial viscous tension and the thickness of the liquid layer?
Viscous tension decreases as the thickness of the liquid layer increases
why is denture adaptation important in maintaining interfacial viscous tension?
maintains a thin layer of saliva
what is adhesion?
the physical attraction of unlike molecules for each other
where is adhesion present in a denture in the mouth?
saliva to denture base
saliva to mucous membrane
what makes adhesive forces bigger?
bigger area covered
what is cohesion?
the physical attraction between similar molecules
where is cohesion present in a denture in the mouth?
in the saliva
remember: quick tip
Adhesive forces are bread encasing the cohesive forces (filling)
explain atmospheric pressure in a denture
mucosa can be distorted to acts as a suction cup to resist displacement
the pressure underneath the denture is lower than atmospheric pressure
what is important in a denture to maintain atmospheric pressure?
border seal in maxilla
how is optimum stability and retention gained in a complete denture fitting surface? 3
adequate extension
adequate postdam seal in maxilla
use undercuts to create a path of insertion that is not straight
where is the location of the post-dam seal?
just anterior to the palatine fovea
how is optimum stability and retention gained in complete denture polished surfaces?
contouring of the buccal, lingual and palatal surfaces so work in harmony with muscle function
how is optimum stability and retention gained in complete denture occlusal surfaces? 3
arch form
occlusal plane level
tooth position
where should the teeth be positioned in the maxilla?
slightly buccal to ridge
where should the teeth be positioned in the mandible?
directly over the ridge
