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Questions and Answers
What is one of the primary objectives of pulpal protection?
What is one of the primary objectives of pulpal protection?
Which type of dentin forms in response to aging or mild irritation such as slow advancing caries?
Which type of dentin forms in response to aging or mild irritation such as slow advancing caries?
Which of the following agents is primarily responsible for the protection of the dental pulp?
Which of the following agents is primarily responsible for the protection of the dental pulp?
What is a characteristic of tertiary dentin compared to primary dentin?
What is a characteristic of tertiary dentin compared to primary dentin?
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Which function do liners serve in deep cavities beneath metallic restorations?
Which function do liners serve in deep cavities beneath metallic restorations?
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What are odontoblasts primarily responsible for?
What are odontoblasts primarily responsible for?
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What can lead to pulp inflammation during dental procedures?
What can lead to pulp inflammation during dental procedures?
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What defines sclerotic dentin's clinical appearance compared to normal dentin?
What defines sclerotic dentin's clinical appearance compared to normal dentin?
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In which situation is tertiary dentin primarily formed?
In which situation is tertiary dentin primarily formed?
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How does the dentinal smear layer affect dentinal tubules?
How does the dentinal smear layer affect dentinal tubules?
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What is the primary action of eugenol in dental treatments?
What is the primary action of eugenol in dental treatments?
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Which of the following is a requirement of ideal dental cements?
Which of the following is a requirement of ideal dental cements?
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What is the purpose of using a calcium hydroxide liner beneath restorations?
What is the purpose of using a calcium hydroxide liner beneath restorations?
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Which material is NOT commonly used as a cavity base?
Which material is NOT commonly used as a cavity base?
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What constitutes the major ingredient of Zinc Phosphate Cement powder?
What constitutes the major ingredient of Zinc Phosphate Cement powder?
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What is the potential drawback of using ZOE cement in composite restorations?
What is the potential drawback of using ZOE cement in composite restorations?
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Which material is recommended for direct and indirect pulp capping due to its unique properties?
Which material is recommended for direct and indirect pulp capping due to its unique properties?
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What is a primary benefit of using TheraCal LC in dental procedures?
What is a primary benefit of using TheraCal LC in dental procedures?
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In the context of moderately deep tooth excavations with amalgam, when should a liner be applied?
In the context of moderately deep tooth excavations with amalgam, when should a liner be applied?
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What characteristic does TheraCal LC possess that enhances its dental applications?
What characteristic does TheraCal LC possess that enhances its dental applications?
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What is a significant advantage of polycarboxylate cement compared to zinc phosphate cement?
What is a significant advantage of polycarboxylate cement compared to zinc phosphate cement?
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What must be done to increase the bond strength of polycarboxylate cement to tooth structure?
What must be done to increase the bond strength of polycarboxylate cement to tooth structure?
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What is the primary bonding mechanism of polycarboxylate cement to tooth structure?
What is the primary bonding mechanism of polycarboxylate cement to tooth structure?
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In cases of shallow tooth excavation, what is required for pulpal chemical protection?
In cases of shallow tooth excavation, what is required for pulpal chemical protection?
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Which of the following is a characteristic of resin-modified glass ionomer (RMGI) in relation to tooth restoration?
Which of the following is a characteristic of resin-modified glass ionomer (RMGI) in relation to tooth restoration?
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Study Notes
Objectives of Pulp Protection
- Dentinal Tubules contain cellular extensions surrounded by dentinal fluid
- Odontoblasts are columnar cells embedded in predentin
- Insult (trauma, bacteria) can cause fluid flow in/out of dentinal tubules, triggering sensitivity (mechanoreceptors) and inflammation.
- Smear Layer (compacted cutting debris) provides partial dentinal tubule sealing (25-30% porous)
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Pulp Defense Mechanisms:
- Sclerotic Dentin: Forms in response to stimuli like aging or mild irritation, sealing dentinal tubules, appearing dark and harder than normal dentin
- Tertiary Dentin (Reparative): Forms in response to acute stimuli (caries, procedures), less mineralized, containing irregular dentinal tubules
Terminology and Classification
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Liners: Thin layers placed in deep cavities beneath restorations
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Actions:
- Prevent chemical passage
- Eugenol (sedative) relieves pulpal inflammation
- Calcium Hydroxide stimulates reparative dentin and dentin bridging
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Actions:
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Bases (Cement Bases): Thick layers used beneath restorations
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Actions:
- Mechanical support for restorations, preventing disruption of the pulp
- Thermal protection for the pulp
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Materials:
- Zinc Phosphate
- Zinc Oxide-Eugenol
- Zinc Poly-carboxylate
- Glass Ionomer
-
Actions:
Requirements of Ideal Dental Cements
- Nontoxic, Nonirritant
- Insoluble in Fluids
- Antibacterial Effect
- Obtunding Effect (Pain Relief)
- Chemical Adhesion to Tooth
- Low Film Thickness
- Thermal Expansion Matches Tooth Structure
- Dimensional Stability
Zinc Phosphate Cement
- Powder: 90% ZnO
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Liquid: 50% H3PO4
- Aluminum Phosphate and Zinc Phosphate decrease reaction rate and stabilize pH
Zinc Polycarboxylate Cement
- Powder: Zinc Oxide
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Liquid: Poly-acrylic Acid or acrylic acid copolymer
- Types: Conventional (separate powder and liquid), Water-Settable (powder and freeze dried poly-acid mixed with water)
Biocompatibility of Polycarboxylate Cement
- More compatible than Zinc Phosphate Cement:
- Lower intrinsic toxicity
- Faster rise in pH towards neutrality
- Larger molecular size blocks dentinal tubules
- Minimal fluid movement in dentinal tubules
Bonding to Tooth Structure
- 10% Polyacrylic acid conditioning for 10 seconds increases bond strength
- Chemical bonding (primary) via COOH groups with Calcium in hydroxyapatite
- Hydrogen bonding (secondary) between hydrogen and organic components of enamel and dentin
TheraCal LC
- Light-cured, resin-modified calcium silicate
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Actions:
- Stimulates hydroxyapatite and secondary dentin bridge formation
- Alkaline pH promotes healing and apatite formation
- Protects and insulates the pulp
- Moisture tolerant and radiopaque
Clinical Considerations
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Factors Influencing Liner/Base Choice:
- Remaining Dentin Thickness (RDT)
- Adhesive Materials
- Type of Restorative Material
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Shallow Excavation (≥1.5-2 mm RDT):
- Amalgam: Varnish, Dentin Sealer, or Bonding system
- Composite: Bonding System
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Moderately Deep Excavation:
- Amalgam: Liner (ZOE or Calcium Hydroxide)
- Composite: ZOE contraindicated
- Deep Cavities: Calcium Hydroxide or RMGI (Glass Ionomer)
- Remaining Thickness: Ensure adequate final restoration thickness after liner/base placement
Summary
- Pulp protection is achieved through liners and bases to protect the pulp from irritation and inflammation.
- The choice of liner and base depends on the depth of the excavation, the material used for the final restoration, and the remaining dentin thickness.
- TheraCal LC is a light-cured, resin-modified calcium silicate ideal for pulpal protection due to its apatite-stimulation ability.
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Description
This quiz explores the objectives and mechanisms of pulp protection in dentistry. Learn about dentinal tubules, odontoblasts, and the body's defense mechanisms like sclerotic and tertiary dentin. Test your knowledge on linings and their purpose in dental procedures.
