Podcast
Questions and Answers
What factor increases denture retention when it is thin and scanty?
What factor increases denture retention when it is thin and scanty?
What mechanical factor increases denture retention?
What mechanical factor increases denture retention?
What physical factor of retention acts when saliva is present?
What physical factor of retention acts when saliva is present?
What type of mucosa is most favorable for denture retention?
What type of mucosa is most favorable for denture retention?
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What happens to denture retention when saliva is more viscous than normal?
What happens to denture retention when saliva is more viscous than normal?
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What is the purpose of placing the teeth in the neutral zone?
What is the purpose of placing the teeth in the neutral zone?
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What is the purpose of properly extended denture borders?
What is the purpose of properly extended denture borders?
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What is the purpose of engaging undercuts in the edentulous region?
What is the purpose of engaging undercuts in the edentulous region?
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What is the usual composition of denture adhesives?
What is the usual composition of denture adhesives?
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What is the purpose of shaping the polished denture surface?
What is the purpose of shaping the polished denture surface?
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Study Notes
Physical Factors of Retention
- Interfacial surface tension is the resistance to separation possessed by the film of liquid between two well-adapted surfaces, found in the thin film of saliva between the denture base and the mucosa of the basal seat.
- A perfect fit is essential for interfacial surface tension to be effective, and it is directly proportional to the size of the basal seat of the denture.
- Capillary attraction (capillarity) is a force that causes the surface of a liquid to become elevated or depressed when it is in contact with a solid, and it helps to retain the denture when the adaptation of the denture base to the mucosa is close.
- Capillary attraction is directly proportional to the area covered by the denture.
- Atmospheric pressure acts to resist dislodging forces applied to the denture, and it requires a perfect seal around the entire border of the denture to be effective.
Retention, Support, and Stability
- Retention is the resistance to the forces of dislodgment along the path of placement.
- Support is the foundation area on which a dental prosthesis rests.
- Stability is the quality of a prosthesis to be firm, steady, or constant, to resist displacement by functional horizontal or rotational stresses.
Factors of Complete Denture Retention
- Physical factors:
- Adhesion: the physical attraction of unlike molecules to each other, effective in direct proportion to the close adaptation of the denture base to the supporting tissues and the fluidity of saliva.
- Cohesion: the physical attraction of like molecules for each other, effective in direct proportion to the area covered by the denture.
- Anatomical factors:
- Mucosa: firm, compressible mucosa of even thickness is most favorable for denture retention, while thick and flabby mucosa will reduce stability.
- Saliva: a medium that allows physical factors of retention to act, with thin, scanty saliva leading to poor retention, and thick viscous saliva increasing denture retention.
- Mechanical factors:
- Shape of the polished denture surface: properly shaped to allow the cheeks and tongue to stabilize the denture.
- Wide coverage: covering a wide area by the fitting surface of the denture increases the forces of adhesion and cohesion.
- Placing the teeth in the neutral zone: allowing the oral and facial musculature to supply supplementary retentive forces.
- Engagement of undercuts: possible to allow mechanical resistance to a direct dislodging force.
- Denture borders: properly extended borders help peripheral seal and increase denture retention.
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Description
Understanding the physical factors affecting denture fit, including interfacial surface tension and capillary attraction. Essential for a perfect fit in denture design.
