Lec 8 3 (easy)

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Questions and Answers

What is the primary purpose of a dental impression?

To record the anatomy of the oral cavity (correct)

To create a visual representation of the oral cavity

To fabricate dentures without prior knowledge

To diagnose oral diseases

Which materials are used to fabricate a customized tray for dental impressions?

Aluminum foil and gauze

Wax sheets and acrylic (correct)

Silicone and rubber overlays

Plaster and metal

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

To enhance the appearance of the impression material

To reduce pressure on specific areas during impression (correct)

To increase the pressure on sensitive areas

To disinfect the tray

Which structures in the oral cavity can typically withstand pressure during denture base application?

Teeth and bone Signup and view all the answers

How can further pressure reduction be achieved during the impression process?

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

Which type of mucosa is found in the vestibule, cheeks, and floor of the mouth?

Non keratinized unattached mucosa Signup and view all the answers

What characteristic of supporting areas offers resistance to resorption?

Thick cortical bone Signup and view all the answers

Which type of bone is found along the crest of residual ridges?

Medullary bone Signup and view all the answers

What direction increases support and resistance in relation to the occlusal plane?

Parallel to occlusal plane Signup and view all the answers

Where is fibrous submucosa not typically seen?

In the mid palatine raphe Signup and view all the answers

What is the primary function of the supporting areas in complete dentures?

Absorb functional forces during mastication Signup and view all the answers

Which part of the complete denture closely contacts the supporting area?

Denture base Signup and view all the answers

What can long-term compression forces in bone lead to?

Bone resorption Signup and view all the answers

What is the cameo or art surface of a denture referred to?

Denture flange Signup and view all the answers

What is the role of the occlusal surface in complete dentures?

Creates balance during mastication Signup and view all the answers

What are relief areas in complete dentures intended for?

Reducing pressure on underlying tissues Signup and view all the answers

What do preprosthetic surgeries in denture construction aim to address?

Prepare the mouth for better fitting dentures Signup and view all the answers

Which statement about denture bearing areas is true?

Denture bearing areas include all surfaces contacted by the denture base. Signup and view all the answers

What is the primary support area for a denture according to the anatomical landmarks?

Posterior 2/3rd of the palate Signup and view all the answers

Which of the following is considered a limiting structure for denture base extension?

Labial frenum Signup and view all the answers

What characteristic is NOT required for primary support structures?

Mucosa should be loosely attached Signup and view all the answers

Which area is classified as a relief area that requires pressure relief from the denture base?

Crest of residual ridges Signup and view all the answers

Which structure provides resistance to masticatory forces in the mandible's anatomical landmarks?

Supporting structures Signup and view all the answers

What type of structures are known for providing resistance to masticatory forces?

Supporting structures Signup and view all the answers

Which anatomical landmark is considered a relief area that provides a reduction in pressure for denture bases?

Incisive papilla Signup and view all the answers

What is required for mucosal structures to be effective as supporting structures?

Keratinized and attached Signup and view all the answers

Which structure limits the extension of the denture base at its borders?

Limiting structures Signup and view all the answers

Which of the following is a characteristic of supporting structures?

Bone should be cortical Signup and view all the answers

What is the role of the posterior peripheral seal area?

Ensures stability of the denture base Signup and view all the answers

Which muscle is directly involved with the buccinator region?

Buccinator muscle Signup and view all the answers

What type of structure are the labial frenum and buccal frenum categorized as?

Limiting structures Signup and view all the answers

Which of the following structures serves as primary supporting structures for dentures?

Buccal shelf Signup and view all the answers

What is the main objective of alveoloplasty in pre-prosthetic surgeries?

To reduce sharp bony extensions of the alveolar ridge Signup and view all the answers

Which pre-prosthetic procedure is aimed at increasing the depth of the vestibule?

Vestibular extension/Sulcus deepening Signup and view all the answers

Which of the following procedures aims to decrease uncertainty in mucosal support for dentures?

Debulking of flabby tissues Signup and view all the answers

What is the primary purpose of tuberosity reduction in denture preparation?

To create vertical space for posterior denture base extension Signup and view all the answers

Ridge augmentation is primarily performed to achieve which of the following?

Increase the height of the alveolar ridge Signup and view all the answers

Which option describes a secondary supporting structure for dentures?

Slopes of residual ridge Signup and view all the answers

In pre-prosthetic surgery, which procedure is most invasive?

Alveoloplasty Signup and view all the answers

Study Notes

Module: Prosthodontics 3 (BDS IV/Semester 7)

Lecture covers Denture bearing areas of maxilla & mandible
Lecturer: Dr Vinothkumar Sengottaiyan (@Dr_VK)
Department: Prosthodontics
College: Oman Dental College

Learning Outcomes

Differentiate denture bearing areas (maxillary/mandibular) into supporting, relief, and limiting areas
Plan and prepare denture-bearing areas for complete dentures
Understand pre-prosthetic surgeries needed for denture construction
Identify situations requiring specialist referral

Support - Definition

General foundation area for a dental prosthesis
Resistance against occlusal/functional forces
In complete dentures, the available mouth area for support
Supporting areas best suited for absorbing mastication forces

Parts of a Complete Denture

Denture base/foundation: Contacts the supporting area (impression surface)
- Three subdivisions: Support areas, Relief areas, Peripheral seal/border areas
Denture flange: Surface outside the base; "camouflage/artistic" surface influencing aesthetics, not function
Occlusal surface: Formed by artificial teeth, used to balance dentures during mastication

Denture Bearing Area

Surfaces contacted by the denture base
The picture shows the denture base contacting oral tissues
Hard denture bases (like acrylic) don't change shape during function; occlusal forces transfer to the bearing areas

Forces in Complete Dentures

Forces perpendicular to the occlusal plane are generated during mastication
Forces are transmitted to underlying supporting tissues (compressive forces)
In bone, these forces cause bone resorption
In tissues, forces cause ischemia (blood flow reduction)
Bone resorption and ischemia lead to long-term problems; sometimes, short-term pain, ulceration, or irritation is possible.

What Happens When We Make an Impression?

Dental impressions record oral cavity anatomy using trays and appropriate materials
Material pressure on structures is compression
Denture bases apply similar force as impression-making
Some structures (teeth, bone) withstand pressure longer, whereas others (mucosa, muscles) can be compressed easily.

How to Manage Compression in Denture Bases?

Custom-made trays only contact pressure-resistant areas
A primary cast is made from a preliminary impression
Wax sheets (relief wax) are placed where pressure reduction is needed during the impression-making process
A tray with acrylic is fabricated
Wax is removed, and a final impression is taken
Relief holes in the tray reduce pressure further

Anatomical Landmarks

Visible/palpable structures in edentulous patients' oral cavities
Useful for impressions and casts
Knowledge of classifications is essential for custom trays using selective pressure during impression making
- Support areas (primary and secondary)
- Relief areas
- Border/peripheral seal areas

Tissues of Edentulous Oral Cavity

Mucosa:
- Keratinized attached (residual ridge/palate)
- Non-keratinized unattached (vestibule, cheeks, mouth floor, soft palate, uvula, tonsillar pillars)
Submucosa: (not in mid-palatine raphe); Fibrous; Fatty/glandular (posterior palate/floor of mouth)
Muscular: Along vestibule, cheek, and mouth floor
Bone:
- Cortical bone (most areas except residual ridge crest)
- Medullary bone (along residual ridge crest)

Favorable Characteristics of Supporting Areas

Thick cortical bone (avascular, resists resorption, excellent support)
Thick keratinized attached mucosa (resists trauma, ulceration from denture base movement)
Direction relative to the occlusal plane; Maximum support/resistance when parallel/perpendicular to forces

Maxillary Anatomical Landmarks

Includes various anatomical structures like: Tuberosity, Buccal frenum, Buccal vestibule, Labial vestibule, etc.

Classification of Anatomical Landmarks - Maxilla

Supporting structures (provide mastication force resistance): Bone (cortical), Mucosa (keratinized, attached), Placed perpendicular to occlusal forces
- Primary support (posterior 2/3rd palate)
- Secondary support (anterior 1/3rd, slopes of residual ridge)
Limiting structures (limit denture base extension): Labial frenum, Labial vestibule, Buccal frenum, Buccal vestibule, Hamular notch, Posterior palatal seal area
Relief areas (relieving pressure on the denture base): Incisive papilla, Mid palatine raphe, Canine eminence, Pterygoid hamulus, Crest of alveolar ridge
Border/peripheral seal areas: All with the same meaning of limiting structures

Anatomical Landmarks of Mandible - Self-Assessment

Students will label diagrams themselves

Classification of Anatomical Landmarks - Mandible

Supporting structures (resistance to masticatory forces): Bone (cortical), Mucosa (keratinized, attached), Perpendicular to occlusal forces
- Primary (buccal shelf)
- Secondary (slopes of residual ridge)
Limiting structures (limit denture base extension): Labial and buccal frenum and vestibules, Pterygo-mandibular raphe, Lingual frenum and vestibule
Relief areas (relieving pressure): Mental foramen area, Crest of ridges, Canine/premolar eminences, Genial/mylohyoid ridges

Preprosthetic Surgeries

Alveoloplasty: reduce sharp bony alveolar ridge extensions
Vestibular extension/sulcus deepening: increase sulcus depth (skin/mucosal grafting)
Tuberosity reduction: create vertical space in posterior ridge accommodating posterior denture bases
Debulking of flabby tissues: achieve a firm mucosal support
Ridge augmentation: increase alveolar ridge height, enhancing denture stability (possibly with implants)

Textbook for Reference

Zarb, G.A., 2012. Prosthodontic Treatment for Edentulous Patients: South Asia Reprint-E-book. Elsevier Health Sciences.

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Description

Test your knowledge on the denture bearing areas of the maxilla and mandible as covered in Prosthodontics 3. This quiz will assess your understanding of supporting, relief, and limiting areas, as well as the preparation of these areas for complete dentures. Explore concepts related to pre-prosthetic surgeries and when to refer to specialists.