Lec 8 (easy)

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Questions and Answers

Where is the primary support area in the maxilla located?

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

Mid palatine raphae

Labial frenum

Buccal shelf

Which of the following is NOT considered a relief area in the maxilla?

Canine eminence

Incisive papilla

Latéral slopes of palate (correct)

Residual ridge crest

What defines peripheral seal areas in dentures?

Areas influenced by tooth structure

Sites of nerve canal locations

Areas where forces are applied to the denture

Areas that determine denture flange length and thickness (correct)

Which area provides primary support in the mandible?

Buccal shelf Signup and view all the answers

Which of the following is considered a relief area in the mandible?

Genial tubercles Signup and view all the answers

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

To resist occlusal forces Signup and view all the answers

Which component of a complete denture is in direct contact with the supporting area?

Denture base Signup and view all the answers

What is the role of the denture flange?

To serve as the art surface for aesthetics Signup and view all the answers

What results from compressive forces caused by mastication in complete dentures?

Bone resorption Signup and view all the answers

Which feature of a complete denture is known as the impression surface?

Denture base Signup and view all the answers

What are the potential short-term effects of using complete dentures?

Pain and irritation Signup and view all the answers

What material is typically used for denture bases to ensure durability during function?

Acrylic Signup and view all the answers

Which areas of the mouth are best suited for absorbing functional forces during mastication?

Support areas 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 of the following structures can withstand pressure during denture fitting?

Bone Signup and view all the answers

What is the purpose of relief wax in making a custom tray?

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

How can the pressure further be reduced when fabricating an impression tray?

By making relief holes in the tray Signup and view all the answers

What characteristic makes cortical bone a favorable supporting area for dentures?

It is resistant to resorption Signup and view all the answers

What types of areas are classified as relief areas during the impression-making process?

Regions where less pressure is desired Signup and view all the answers

Which layer of mucosa is essential for resisting trauma during denture use?

Attached keratinized mucosa Signup and view all the answers

Which anatomical structures are crucial for applying selective pressure in denture impressions?

Supporting and border areas Signup and view all the answers

Study Notes

Support - Definition

Support, in general, is the area a dental prosthesis rests on.
It also refers to the resistance the prosthesis can handle against occlusal/functional forces.
In complete dentures, it's the available mouth area for support.
Supporting areas are the mouth areas best at absorbing functional forces during chewing.

Parts of a Complete Denture

Denture base/denture foundation: The part of the denture that contacts the supporting area (denture bearing area). Also called the impression/intaglio surface, recorded and reproduced by the final impression. It has three subdivisions:
- Support areas
- Relief areas
- Peripheral seal/border areas
Denture flange: The surface outside the denture base. Called the cameo/art surface. Primarily influences the esthetic appeal and doesn't impact function.
Occlusal surface: The surface formed by the artificial teeth. Used to create balance for the denture during chewing.

Denture Bearing Area

Refers to the surfaces contacted by the denture base.
The picture shows the denture base's fitting surface, which contacts the oral tissues.
Denture bases are usually made of hard materials (like acrylic) and don't change shape during function.
Occlusal forces are transferred completely to the denture bearing areas by 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 underlying supporting tissues.
In bone, these forces cause bone resorption.
In tissues, these forces cause ischemia (reduced blood flow).
Bone resorption and ischemia are long-term problems.
Pain, ulceration, and irritation can occur (sometimes immediately or shortly after use).

What Happens When We Make an Impression?

A dental impression records the oral cavity's anatomy using appropriate materials (carried by impression trays).
The material presses against oral structures to record them (compression).
It is assumed that the denture base applies as much force as used during impression making.
Some structures (like teeth and bone) can withstand the pressure, while others (mucosa, muscle attachments) cannot.

How to Manage Compression in Denture Bases

A customized tray is needed, contacting only pressure-resistant areas.
This tray is made from a first duplicate or primary cast from the initial/preliminary impression.
Wax sheets (relief wax) are placed on the duplicate in areas where pressure reduction is needed during impression-making.
A special acrylic tray is then made and, finally, the wax is removed before final impression.
Pressure can also be reduced by creating holes in the tray (relief holes).

Anatomical Landmarks

Visible/palpable anatomical structures are present in the edentulous oral cavity.
These structures are appreciated in both impressions and casts.
Knowledge of how these structures are classified is important in making custom trays to apply selective pressure during impression making.
Key classifications for support include:
- Support areas (primary and secondary)
- Relief areas
- Border areas/peripheral seal areas

Favorable Characteristics of Supporting Areas

Thick cortical bone, which is avascular: Resistant to resorption, providing excellent support.
Thick keratinized attached mucosa: Resists trauma and ulceration due to denture base movements.
Direction related to occlusal plane: Optimal support and resistance are when the supporting area is parallel or perpendicular to occlusal forces.

Relief Areas

Some areas might have favorable support criteria but not be used for support.
Key areas needing relief include:
- Nerve canals (e.g., mental or incisive)
- Sharp bony edges (e.g., canine prominence, interdental bony peaks)
- Fresh extraction socket spaces
- High frenal attachments
- Ridge crest with soft medullary bone
- Areas of thin mucosa (e.g., mid-palatine raphae, external oblique ridge)

Peripheral Seal Areas

These areas determine denture flange length and thickness.
Classified as:
- Frenal areas (where muscles attach)
- Sulcus areas (between attachments where muscles move)

Maxilla - Support and Relief

Primary Support:
- 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 raphae
- Canine eminence
- Undercuts

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 area
Lingual frenum
Alveolo-lingual sulcus

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Description

This quiz covers essential concepts of complete dentures, including definitions of support and the various parts of a denture. You will learn about the denture base, flanges, and occlusal surfaces, as well as their significance in functionality and aesthetics. Test your knowledge on these fundamental components and their roles in dental prosthetics.