Denture Bases and Occlusion Blocks

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Questions and Answers

What is the approximate width of occlusal rims in the anterior region?

4–6 mm

10–12 mm

6–8 mm (correct)

8–10 mm

What is the primary purpose of occlusion rims?

To replace missing teeth

To align the jaw relationships (correct)

To support the bite registration

To determine the size of the denture base

Where should the labial surface of the maxillary occlusion rim be positioned in relation to the incisive papilla?

Approximately 6–8 mm anterior to the incisive papilla (correct)

Approximately 10–12 mm posterior to the incisive papilla

At the middle of the incisive papilla

Approximately 4–6 mm anterior to the incisive papilla

What height should the anterior portion of the mandibular occlusion rim be approximately?

18 mm Signup and view all the answers

What aspect should be continuously communicated to patients regarding record bases and occlusion rims?

They may feel loose due to required adjustments Signup and view all the answers

What is the approximate width of posterior occlusion rims?

8–10 mm Signup and view all the answers

Which line on the occlusion rim helps to determine the width of the artificial teeth?

Canine line Signup and view all the answers

What is the height of the posterior lower region of the mandibular occlusion rim related to?

Equal to a point representing two-thirds the height of the retromolar pad Signup and view all the answers

What is the primary purpose of using occlusion blocks?

To establish facial contours and aid in tooth selection Signup and view all the answers

Which requirement for a trial denture base ensures that it does not distort over time?

Dimensionally stable with minimal warpage Signup and view all the answers

What is the purpose of waxing out undercuts on the master casts?

To protect the master casts from damage during processing Signup and view all the answers

How long should the cast be soaked in room temperature water before making the record base?

5 minutes Signup and view all the answers

Why is a tinfoil substitute used in the process of making the record base?

To protect the cast and allow separation of the record base Signup and view all the answers

What is the ideal thickness of the trial denture base required?

2mm Signup and view all the answers

What component is essential for making interocclusal records?

Occlusion rims Signup and view all the answers

Which of the following statements about the construction of the record base is correct?

It must be made from autopolymerizing acrylic resin Signup and view all the answers

Study Notes

Record Bases and Occlusion Blocks

Definition: Occlusion blocks are composed of occlusion rims attached to well-fitting trial denture bases.
Purpose:
- Establishing facial contours
- Assisting in tooth selection
- Maintaining the vertical dimension of occlusion during record taking
- Making interocclusal records
- Arranging denture teeth
- Creating a waxed-up mold for the external surface of the complete denture

Requirements of a Trial Denture Base

Characteristics:
- Rigid
- Accurately adapted to the cast with proper extensions
- Dimensionally stable with minimal warpage
- Relieved from undercuts to avoid scraping the cast
- Clean and smooth for patient comfort
- Proper and uniform thickness (2mm)
- Easy to construct

Wax Blockout

Purpose: To protect master casts from tissue undercuts and irregularities.
Locations:
- Maxillary casts: Labial of the anterior ridge, rugae areas, sometimes in tuberosity areas laterally.
- Mandibular cast: Retromylohyoid areas.

Record Base Fabrication

Master Cast Preparation:
- The cast is soaked in room temperature water for 5 minutes to expel air and minimize bubble-like defects.
- A tinfoil substitute is used as a separating medium to protect the cast and ensure separation of the record base.
- The tinfoil substitute is applied in two thin layers, allowing the first layer to dry before applying the second.
Record Base Material:
- Fabricated with autopolymerizing acrylic resin.
Thickness:
- Thinner on the crest of the ridges and buccal to the crest of the ridges due to limited space for tooth arrangement.

Occlusion Rims

Material: Generally made of pink modeling wax.
Uses:
- Registration of jaw relationships
- Tooth selection:
  - Midline determination
  - High and low lip line determination for tooth length
  - Canine line determination for tooth width
  - Distance between the canine line and posterior end of the occlusion rim for posterior tooth width
- Setting up teeth
- Support for lips and cheeks

Occlusion Rim Dimensions

Width:
- Approximately 8–10 mm in the posterior region
- 6–8 mm in the anterior region
Maxillary Occlusion Rim:
- Labial surface in the central area is approximately 6-8 mm anterior to the middle of the incisive papilla and is inclined labially.
Mandibular Occlusion Rim:
- Vertical height is about 18mm.
- Posterior lower region height is equal to two-thirds the height of the retromolar pad (middle to upper third).

Important Considerations

Patient Communication: Continuously inform patients that the record bases and occlusion rims are not permanent parts of the dentures and may feel loose due to blocked-out undercuts.

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Description

This quiz explores the essential features and purposes of occlusion blocks and trial denture bases in prosthodontics. It covers the characteristics required for trial denture bases and the importance of wax blockout in protecting master casts. Test your understanding of these fundamental concepts in denture construction.