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Questions and Answers
What is the primary purpose of the denture base?
What is the primary purpose of the denture base?
Which of the following is NOT a method of polymerizing denture base resin?
Which of the following is NOT a method of polymerizing denture base resin?
What happens to resin during polymerization?
What happens to resin during polymerization?
Which material is most commonly used for denture base construction?
Which material is most commonly used for denture base construction?
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What is an advantage of metal-based dentures?
What is an advantage of metal-based dentures?
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What occurs to dentures when they absorb water from their storage fluid?
What occurs to dentures when they absorb water from their storage fluid?
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Which of the following is an aspect of denture tissue conditioners?
Which of the following is an aspect of denture tissue conditioners?
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What does the light activation polymerization method primarily utilize?
What does the light activation polymerization method primarily utilize?
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What is a disadvantage of porcelain teeth in dentures?
What is a disadvantage of porcelain teeth in dentures?
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Which of the following is an advantage of polymer (plastic) teeth compared to porcelain teeth?
Which of the following is an advantage of polymer (plastic) teeth compared to porcelain teeth?
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What occurs over time after tooth extraction that affects dentures?
What occurs over time after tooth extraction that affects dentures?
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What should a clinician do if there is a large space due to ridge loss?
What should a clinician do if there is a large space due to ridge loss?
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Which type of denture reline material is designed to mimic autopolymerizing denture base material?
Which type of denture reline material is designed to mimic autopolymerizing denture base material?
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Which of the following is a disadvantage associated with using polymer (plastic) teeth?
Which of the following is a disadvantage associated with using polymer (plastic) teeth?
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What negative effect can poor denture fit due to ridge resorption have?
What negative effect can poor denture fit due to ridge resorption have?
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What is the primary reason for choosing a complete new denture over a reline?
What is the primary reason for choosing a complete new denture over a reline?
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What is the primary advantage of laboratory-processed relines using heat and pressure?
What is the primary advantage of laboratory-processed relines using heat and pressure?
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What is a major disadvantage of the silicone-based reline material?
What is a major disadvantage of the silicone-based reline material?
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Why must tissue conditioners be frequently replaced?
Why must tissue conditioners be frequently replaced?
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What technique is used to improve the strength of polymer during denture repair?
What technique is used to improve the strength of polymer during denture repair?
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What is the transverse strength of heat-polymerized repairs compared to the original material?
What is the transverse strength of heat-polymerized repairs compared to the original material?
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Which type of impression material is characterized as an irreversible hydrocolloid?
Which type of impression material is characterized as an irreversible hydrocolloid?
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What happens when trying to accelerate the setting of alginate?
What happens when trying to accelerate the setting of alginate?
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What does the loss of resiliency in tissue conditioners indicate?
What does the loss of resiliency in tissue conditioners indicate?
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Which type of elastomeric impression material is specifically designed to minimize distortion of movable tissues?
Which type of elastomeric impression material is specifically designed to minimize distortion of movable tissues?
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What is a key characteristic of Polyvinyl Siloxane (PVS) regarding water absorption?
What is a key characteristic of Polyvinyl Siloxane (PVS) regarding water absorption?
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Which type of dental stone is considered the weakest and is very soft in consistency?
Which type of dental stone is considered the weakest and is very soft in consistency?
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What is the primary method of disinfecting Polyether materials?
What is the primary method of disinfecting Polyether materials?
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In dental applications, which type of stone is best known for its low expansion and high strength?
In dental applications, which type of stone is best known for its low expansion and high strength?
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Baseplate wax is available in three different hardness levels. Which level is typically used for denture base construction?
Baseplate wax is available in three different hardness levels. Which level is typically used for denture base construction?
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Which dental stone type would be used when a relatively high strength is required but at a lower cost?
Which dental stone type would be used when a relatively high strength is required but at a lower cost?
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How do dental stones behave during the curing process?
How do dental stones behave during the curing process?
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What type of denture cleanser is recommended for its ability to capture delicate, distortable tissues?
What type of denture cleanser is recommended for its ability to capture delicate, distortable tissues?
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Which of the following is a potential consequence of using sodium hypochlorite on removable partial dentures?
Which of the following is a potential consequence of using sodium hypochlorite on removable partial dentures?
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What should not be used when the denture base contains a soft liner?
What should not be used when the denture base contains a soft liner?
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In what scenario are denture adhesives primarily required?
In what scenario are denture adhesives primarily required?
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Which of these statements about mild acids is correct regarding denture cleaners?
Which of these statements about mild acids is correct regarding denture cleaners?
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What is the primary function of oxygenating agent solutions?
What is the primary function of oxygenating agent solutions?
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Which statement correctly describes powder-based denture products?
Which statement correctly describes powder-based denture products?
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What is a major characteristic of paste-based denture products?
What is a major characteristic of paste-based denture products?
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Study Notes
Denture Base Materials
- Denture bases are made from polymers or metal.
- Polymers are a popular choice due to their easy shaping and lightweight properties.
- The purpose of the denture base is to:
- Cover the residual ridge
- Provide facial contour
- Hold the artificial denture teeth in the correct position
- Provide intimate contact without interfering with cheek or tongue movements
Polymethyl Methacrylate (PMMA)
- PMMA is the most widely used material for denture bases.
- It is a polymer that can undergo different polymerization methods.
Polymerization Methods
- Heat Polymerization: PMMA is heated to initiate polymerization.
- Chemical Reaction (Autopolymerized): A chemical reaction triggers polymerization.
- Microwave Energy: Microwaves are used to initiate polymerization.
- Light Activation: Light energy initiates polymerization.
Resin-Based Dentures (Heat-Polymerized Materials)
- An important stage in acrylic polymerization is the dough stage, when the acrylic is ready for use.
- Dentures must be kept wet to counteract shrinkage and expand to near original dimensions.
- Shrinkage during polymerization is approximately 0.3-0.5%.
Auto-Polymerized Materials
- These materials are polymerized at room temperature.
- Autopolymerized materials are generally weaker and less durable than heat-polymerized materials.
Microwave Cured Acrylic Resin
- This method utilizes microwaves for faster polymerization.
Light Cured Resin
- Polymerization is triggered by light exposure.
Metal-Based Dentures
- The tissue-bearing side of the denture is made of metal.
- Polymer is used to hold the teeth and mimic gingiva.
- Advantages of metal bases:
- More accurate fit
- Transfer heat from foods and fluids to the palate
- May enhance retention for mandibular dentures
Tooth Retention
- Denture teeth are held in place by:
- Mechanical undercut
- Micromechanical retention
Porcelain Teeth
-
Advantages:
- Hard and wear-resistant, reducing the likelihood of occlusal vertical dimension loss.
-
Disadvantages:
- Hardness can lead to excessive wear of natural teeth.
- Transmits biting forces to the underlying mucosa, accelerating bone resorption.
- Susceptible to fracture.
- Can produce a clicking sound.
- Difficult to contour to fit the ridge.
Polymer (Plastic) Teeth
-
Advantages:
- Softer than porcelain, reducing stress on the ridge.
- Less wear-resistant, minimizing wear on opposing teeth.
- Easily adaptable to fit ridges.
- Less prone to fracture than porcelain.
-
Disadvantages:
- Occlusal surfaces wear more rapidly.
Denture Liners
- Denture liners are used to address the space that develops between the denture base and the residual ridge due to bone resorption.
Denture Relining (Chairside or Laboratory)
-
Chairside Reline Materials:
- Used to restore a denture's fit by adding a layer of new plastic to the denture base.
- Two types:
- Powder and liquid, similar to autopolymerized denture base material.
- Single cartridge placed in a delivery gun. - Laboratory Reline Materials:
- Processed in a laboratory.
- The denture base is roughened, an impression is taken, and new materials are added to the existing base.
- Two types:
- A new denture base material is added and polymerized against the old base.
- A soft, silicone-based reline material is employed.
Denture Tissue Conditioners
- These temporary liners provide cushioning and promote healing of irritated and inflamed tissues.
- They must be replaced frequently to prevent hardening and loss of resiliency.
Denture Repair
- Denture repair involves using autopolymerizing resin to replace lost teeth or rejoin fractured denture bases.
- Locks and undercuts can be created using liquid acrylic to form a stronger bond.
Impression Materials
-
Alginate Hydrocolloid (an irreversible hydrocolloid)
- Used for taking impressions.
-
Polyvinyl Siloxane (PVS) and Polyether
- Elastomeric materials commonly used for making final impressions.
PVS
- Available in various viscosities:
- Light-bodied
- Medium-bodied
- Heavy-bodied
- Putty
- The viscosity is chosen based on the consistency of the tissues being impressed.
- PVS is hydrophobic and can be disinfected by soaking in any disinfectant.
Polyether
- Polyether absorbs water (hydrophilic).
- Disinfection is achieved by spray methods and storing in a plastic bag.
- Polyether impressions can be poured later.
Dental Stones
- Dental stones vary in hardness, strength, surface detail, and setting expansion.
- Factors influencing stone properties include water-to-powder ratio and mixing technique.
- Vacuum spatulation is recommended for optimal results.
- Dental stones release heat during curing (exothermic).
Types of Stones
- Type I (Impression Plaster): Very soft and weak.
- Type II (Model Plaster, Mounting Stone): Highest setting expansion, but weaker than Type III and IV.
- Type III (Dental Stone): Less strong than Type IV, but slightly higher expansion; commonly used for master casts; offers good strength and lower cost.
- Type IV (High-Strength Stone): Very hard, strong, wear-resistant, and low expansion; ideal for demanding applications.
Interocclusal Registration Materials
- Used to record the relationship between the maxillary and mandibular arches.
- Common materials include thermoplastic materials and polyvinyl siloxane.
Dental Waxes
- Dental waxes play a crucial role in denture fabrication.
- Dental waxes are categorized according to hardness and flowability.
Baseplate Wax
- Available in three hardness levels (room temperature, body temperature, and elevated temperature).
- Type 1 wax is mainly used in denture base construction.
Sticky Wax
- A soft wax that is sticky and adhesive.
- Used to secure parts together before processing.
Low-Melting Impression Wax
- Used to capture delicate tissues in a non-functional state.
- Can be painted over impression trays to capture delicate and distortable tissues.
Denture Cleansers
- Denture cleansers are either abrasive or solutions-based.
Abrasive Cleansers
- Use paste-based cleansers with soft-bristled brushes for effective cleaning.
Solution Cleansers
- Solution cleansers are divided into:
- Hypochlorites: Antibacterial agents that remove protein and kill organisms but can be corrosive to metals.
- Oxygenating Agents: Peroxides, perborates, and percarbonates, released by tablets or powders, are used for disinfection.
- Mild Acids: Can potentially etch the natural teeth.
Denture Adhesives
- Denture adhesives are generally not required if the denture is properly fabricated.
- Used in emergency situations or when there is minimal residual ridge to provide stability.
Indications for Denture Adhesives
- Minimal residual ridge to improve lateral resistance.
- Edentulous patients with cleft palates.
- Patients wearing post-cancer treatment intraoral prostheses
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Description
This quiz covers denture base materials, focusing on polymers and metals, specifically PMMA. It discusses various polymerization methods like heat, chemical, microwave, and light activation used for creating denture bases. Test your understanding of these essential concepts in denture fabrication.
