Lec 8 (hard)

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Questions and Answers

What best describes the function of the denture base?

It provides the esthetic appearance of the denture.

It serves as a decorative external surface.

It transfers occlusal forces to the underlying tissues. (correct)

It specifically holds the artificial teeth in place.

Which of the following areas is NOT part of the denture base?

Occlusal surface (correct)

Peripheral seal areas

Relief areas

Support areas

What effect do compressive forces generated during mastication have on bone?

They have no impact on bone structure.

They lead to bone resorption. (correct)

They encourage bone growth.

They increase bone density.

Which part of the complete denture influences esthetics but does not significantly affect function?

Denture flange Signup and view all the answers

What is the primary role of relief areas in a denture?

To accommodate undercut areas in the oral cavity. Signup and view all the answers

What can result from the compressive forces exerted by a complete denture on oral tissues?

Chronic ischemia. Signup and view all the answers

What materials are commonly used to fabricate denture bases due to their properties?

Hard materials like acrylic that do not change shape. Signup and view all the answers

What is the definition of denture bearing area?

All surfaces contacted by the denture base. Signup and view all the answers

Which area provides primary support in the mandible?

Buccal shelf Signup and view all the answers

What is considered a relief area in the maxilla?

Residual ridge crest Signup and view all the answers

Which structure represents a peripheral seal area in the mandible?

Retro molar pad area Signup and view all the answers

Which of the following is classified as a relief area in the mandible?

Mental foramen Signup and view all the answers

What constitutes the primary support area in the maxillary arch?

Horizontal surface of posterior 2/3 of the palate Signup and view all the answers

What is the primary purpose of a dental impression?

To create a model of the oral cavity's anatomy using impression materials. Signup and view all the answers

Which types of oral structures can withstand compression during the denture-making process?

Teeth and bone. Signup and view all the answers

What is the purpose of using relief wax in the custom tray fabrication process?

To reduce pressure in specific areas during the impression. Signup and view all the answers

What type of anatomical landmarks are crucial for making a custom tray that applies selective pressure?

Both visible and palpable anatomical structures. Signup and view all the answers

Which characteristic makes cortical bone an excellent supporting structure?

It is resistant to resorption and avascular. Signup and view all the answers

What are relief holes used for in the impression tray?

To further reduce pressure during the impression process. Signup and view all the answers

What is a key feature of keratinized attached mucosa that contributes to its favorable characteristics?

Thick and resistant to trauma. Signup and view all the answers

Why is it important to classify anatomical landmarks when making a custom tray?

To apply selective pressure based on the resistance of different areas. Signup and view all the answers

Study Notes

Support - Definition

Support is the foundation area for a dental prosthesis.
It also refers to the amount of resistance the prosthesis can withstand against occlusal/functional forces.
In complete dentures, support is the area of the mouth available to support the denture.
In other cases, supporting areas are the areas in the mouth best suited for absorbing functional forces during chewing.

Parts of Complete Denture

Denture base/denture foundation: The part of the denture that contacts the supporting area (also called the denture-bearing area or impression surface/intaglio surface). It has subdivisions:
- Support areas
- Relief areas
- Peripheral seal/border areas
Denture flange: The surface outside the denture base (sometimes called the cameo/art surface). It is designed by the dentist to affect aesthetics, but not the function.
Occlusal surface: Created by the artificial teeth and used to maintain balance during chewing.

Denture Bearing Area

Refers to the surfaces of the denture base that contact the oral tissues.
The image shows the denture base's fitting surface, contacting the oral tissues.
Denture bases are usually made of hard materials like acrylic and do not change shape during use.
All occlusal forces are transferred to the denture-bearing areas through the denture base.

Forces in Complete Dentures

Forces perpendicular to the occlusal plane are generated during chewing.
These forces are transmitted as compressive forces to the supporting tissues beneath.
In bone, these forces cause bone resorption.
In oral tissues, the forces create ischemia (reduced blood flow).
Bone resorption and ischemia are long-term problems.
In some cases, pain, ulceration, and irritation may occur immediately or shortly after denture use.

What Happens When We Make an Impression?

A dental impression records the oral cavity's anatomy using appropriate materials in impression trays.
The impression material is pressed against oral structures to record them. This is compression.
The denture base applies as much force during an impression as is applied in making it.
Some structures (teeth, bone) can withstand this force, but others (mucosa, muscle attachments) cannot and may compress.

How to Manage Compression in Denture Bases

To manage compression, a custom tray is created, contacting only the areas that can resist pressure.
The tray is created from a preliminary impression duplicate (primary cast).
Wax sheets (relief wax) are placed in areas where we want to reduce pressure during the impression process.
The wax is then removed, constructing the final acrylic tray.
To further reduce pressure, relief holes could be added.

Anatomical Landmarks

Anatomical structures visible/palpable in the oral cavity of an edentulous patient are important to understand.
Impressions and casts show these structures.
Knowledge of how these structures are classified helps in creating custom trays for selective pressure during impressions.
Support areas are classified as primary and secondary.
Relief areas are also classified.
Border areas/peripheral seal areas are defined.

Favorable Characteristics of Supporting Areas

Thick cortical bone: Avascular, resistant to resorption, and excellent support.
Thick keratinized attached mucosa: Resists trauma, ulceration, and movement effects from denture bases.
Direction in relation to the occlusal plane: Max support/resistance when the area is parallel or perpendicular to occlusal forces.

Relief Areas

Sometimes, suitable areas for support may not provide sufficient support.
Relief areas include:
- Nerve canals (mental and incisive).
- Sharp bony edges (canine prominences, interdental peaks).
- Fresh extraction socket spaces.
- High frenum attachments.
- Ridge crests with soft medullary bone.
- Thin mucosal areas (mid palatine raphae, external oblique ridge).

Peripheral Seal Areas

These areas determine denture flange length and thickness.
Classification:
- Frenal areas: Where the muscles attach.
- Sulcus areas: Between attachments where muscles move.

Maxilla - Support and Relief

Primary Support: the horizontal surface of the posterior 2/3 of the palate.
Secondary Support: Anterior and lateral slopes of the palate, residual ridge slopes.
Relief Areas:
- Residual ridge crest.
- Incisive papilla.
- Mid palatine raphe.
- Canine eminence.
- Undercuts (if any).

Maxilla - Peripheral Seal Areas

Labial sulcus
Labial frenum
Buccal sulcus
Buccal frenum
Hamular notch
Posterior palatal seal area

Mandible - Support and Relief

Primary Support: Buccal shelf
Secondary Support: Residual ridge slope
Relief Areas:
- Residual ridge crest
- Mental foramen
- Mylohyoid ridge
- Genial tubercles

Mandible - Peripheral Seal Areas

Labial frenum
Labial sulcus
Buccal frenum
Buccal sulcus
Retromolar pad areas
Lingual frenum
Alveolo-lingual sulcus

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Description

Test your knowledge on the support and parts of complete dentures. This quiz covers definitions, functions, and the anatomy involved in dental prosthesis. Perfect for dental students and professionals looking to reinforce their understanding of these concepts.