4. Medical history & General Principles Flashcards
Age and adaptability to new prostheses?
Worse adaptability due to worse tissues
What size lips are better when assesing a patient for dentures?
bigger lips
What happens to the floor of the mouth of an edentulous patient?
- Goes up due to progressive resorption of the ridge
What restricts the extension of the dentures base?
Mobile tissues insertion
What happens to the VD of an edentulous patient? (2)
-reduced b/c lack of teeth - mandible goes up to get in contact with maxilla
What supplemental exams are needed for dentures? (3)
• Orthopantomogram. - Impacted teeth. - Cysts. - Remaining roots. • Periapical radiographs. • Computerized tomography, nuclear magnetic tomography, biopsy, sialography.
Two kinds of forces act upon a complete denture:
- Passive forces: Forces while the mouth is at rest. - Functional forces: Forces while in function (chewing, swallowing, talking, drinking…)
Displacement forces of a denture? (3)
• Intrussive forces: Tend to impact the denture over the supporting structures. • Extrussive forces: Tend to move the denture out of place. *dentures must be capable of minimizing this forces
Opposing forces for displacement of a denture? (3)
• Support » opposes to intrusive forces. • Retention and stability » oppose to extrusive forces. - Retention: opposes all vertical extrusive forces. - Stability: opposes all lateral extrusive forces.
Define Support (3)
- relationship b/w denture base and supporting tissues -opposes intrusive forces - surface of denture
Define retention
- Resisting the forces of dislodgment along the path of placement - opposes all vertical extrusive forces.
Define stability
opposes all lateral extrusive forces.
What bears the load in complete dentures? (2)
- always tissue-supported, although in the end bone is what bears the load - Attached gingiva and bone are the supporting structures, but support is the capability of the denture
Bad support is implied by? (2)
- Bad supporting tissue (ex. mobile gingiva) - bad denture fit
What factors are involved in retention? (4)
• Adhesion. • Cohesion. • Border seal. • Other factors.
Define adhesion: (2)
-property of remaining close in proximity - physical attraction of molecules of DIFFERENT bodies
How does adhesion occur with dentures? (2)
- Between denture and saliva - Between saliva and mucosa.
Adhesion related to space between denture and mucosa?
-wider space = less adhesion = less retention
What factors increase adhesion (Retention)? (3)
- more supporting surface of denture - thicker saliva **TOO thick saliva can hinder impression taking by increasing hydraulic pressure between denture and mucosa
Define cohesion:
sticking together of particles of the SAME substance
What causes higher retention in relation to cohesion? (3)
- More Saliva b/c located between the denture and supporting mucosa - more saliva cohesion = more surface tension = more retention - more supporting surface of denture = higher retention
Does the upper or lower denture have more retention? (2)
Upper. -lower= less retention b/c of cohesion and adhesion
Define border seal: (2)
- Contact of the denture border with the underlying or adjacent tissues to prevent the passage of air or other substances - a negative pressure at inner surface of denture (vacuum)
Border seal is also know as?
Peripheral seal
