Lec 8 (medium)

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Questions and Answers

What is the primary support area for the maxilla?

Residual ridge slopes

Mid palatine raphae

Horizontal surface of posterior 2/3 of the palate (correct)

Anterior and lateral slopes of palate

Which of the following is a relief area in the maxilla?

Incisive papilla (correct)

Buccal shelf

Labial sulcus

Mental foramen

What type of area are the hamular notch and posterior palatal seal classified under?

Frenal areas

Support areas

Peripheral seal areas (correct)

Relief areas

Which of the following is NOT a relief area in the mandible?

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

Which area provides primary support for the mandible?

Buccal shelf Signup and view all the answers

What is the primary purpose of a dental impression?

To record the anatomy of the oral cavity Signup and view all the answers

Which structure is least likely to withstand pressure during denture base application?

Mucosa Signup and view all the answers

What is the function of relief wax in the impression process?

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

How are relief holes used in the tray for making impressions?

To reduce pressure further by allowing air escape Signup and view all the answers

What is a key characteristic of supportive areas in the oral cavity?

Thick keratinized attached mucosa Signup and view all the answers

What is a supported area in the context of a custom tray?

An anatomical structure that efficiently supports pressure Signup and view all the answers

How is a customized tray typically fabricated?

With an initial impression and relief wax on a duplicate cast Signup and view all the answers

What is the major benefit of knowing anatomical landmarks in edentulous patients?

It aids in the classification and application of selective pressure during impressions Signup and view all the answers

What does the term 'support' refer to in the context of dental prosthesis?

The area that the prosthesis rests on and its resistance to forces Signup and view all the answers

Which part of a complete denture is known as the 'denture foundation'?

Denture base Signup and view all the answers

What is the primary function of the denture flange in a complete denture?

To enhance aesthetics without affecting function Signup and view all the answers

What term is used to describe the areas that best absorb functional forces during mastication?

Supporting areas Signup and view all the answers

What type of forces are predominantly generated in complete dentures during mastication?

Perpendicular forces Signup and view all the answers

Which condition can result from the compressive forces transferred through the denture base to the underlying tissues?

Bone resorption Signup and view all the answers

What describes the 'denture bearing area'?

The surface that touches the supporting tissues Signup and view all the answers

What short-term problems can occur due to improper force distribution in complete dentures?

Pain, ulceration, and irritation Signup and view all the answers

Study Notes

Support - Definition

Support, in general, is the base area where a dental prosthesis rests.
It also refers to the resistance a prosthesis can withstand against occlusal/functional forces.
In complete dentures, support is the available area in the mouth to support the denture.
In other cases, supporting areas are locations in the mouth best suited to absorb the functional forces during chewing.

Parts of Complete Denture

Denture base/denture foundation: The part of the denture contacting the supporting area (denture bearing area).
- Also known as the impression surface or intaglio surface.
- Recorded and reproduced from final impressions.
- Has subdivisions:
  - Support areas
  - Relief areas
  - Peripheral seal/border areas
Denture flange: The surface outside the denture base.
- Also called cameo/art surface.
- Created by the dentist.
- Affects aesthetics, not function in most cases.
Occlusal surface: The surface formed by artificial teeth.
- Used to create balance for dentures during chewing.

Denture Bearing Area

Refers to all surfaces the denture base contacts.
The image shows the denture base's fitting surface, which contacts oral tissues.
Denture bases are typically made of hard materials like acrylic.
They maintain shape during function.
All occlusal forces are transferred to the denture bearing areas via the denture base.

Forces in Complete Dentures

Forces perpendicular to the occlusal plane are generated during chewing.
These forces are transmitted to supporting tissues as compressive forces.
Compressive forces in bone cause bone resorption.
Compressive forces in tissues cause ischemia (reduced blood flow).
Bone resorption and ischemia are long-term problems.
Sometimes, pain, sores, and irritation occur immediately or shortly after use.

What Happens When We Make an Impression?

A dental impression records the oral anatomy.
Appropriate impression materials are carried by impression trays.
The material is pressed against oral structures to create a record.
Pressing against these structures constitutes compression.
The denture base should apply as much force as used to create the impression.
Some structures like teeth and bone withstand pressure.
Other structures (mucosa, muscle attachments) compress easily.

How to Manage Compression in Denture Bases

To manage pressure, a customized tray should be made.
The tray contacts only pressure-resistant areas.
The tray is made from a duplicate (primary cast) of an initial/preliminary impression.
Wax (relief wax) is placed in areas requiring pressure reduction during impression taking.
A special acrylic tray is created following wax removal.
Further pressure reduction can be achieved through holes in the tray (relief holes).

Anatomical Landmarks

Anatomical structures in the edentulous mouth are visible and palpable.
These structures are visible in impressions and casts.
Understanding these structures and how they are classified aids in custom tray creation, allowing for selective pressure application during impressions.
Key classifications:
- Support areas - primary, secondary
- Relief areas
- Border areas/peripheral seal areas

Favorable Characteristics of Supporting Areas

Thick cortical bone: Avascular, resistant to resorption, excellent support.
Thick keratinized attached mucosa: Resists trauma and ulcers caused by denture movement.
Direction relative to the occlusal plane: Optimal support and resistance when the area is parallel to the occlusal plane.

Relief Areas

Sometimes, favorable support criteria are present, but these areas do not provide support.
Key relief areas:
- Nerve canals (mental, incisive)
- Sharp bony edges (canine prominence, interdental peaks)
- Fresh extraction socket spaces
- Frenal attachments
- Areas with soft medullary bone
- Areas of thin mucosa (mid palatine raphe, external oblique ridge).

Peripheral Seal Areas

These areas determine denture flange length and thickness.
Classification:
- Frenal areas: Where muscles attach.
- Sulcus areas: Spaces between attachment points where muscles move.

Maxilla - Support and Relief

Primary support: Horizontal surface of 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 raphae, canine eminence, undercuts (if any).

Maxilla - Peripheral Seal Areas

Key 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

Key areas:
- Labial frenum
- Labial sulcus
- Buccal frenum
- Buccal sulcus
- Retromolar pad area
- Lingual frenum
- Alveolo-lingual sulcus

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Description

Explore the foundational aspects of complete dentures, focusing on support areas and key parts like the denture base and flange. This quiz covers definitions, functions, and subdivisions essential for understanding dental prosthetics. Test your knowledge on how these components contribute to the fit and function of dentures.