Dental Anatomy: Loss of Enamel and Dentin

Questions and Answers

What is a consequence of enamel or dentin loss due to lesions or cavities?

Enhancement of protective properties of the tooth

Exposure of the dentin-pulp system to various irritations (correct)

Increased resistance to thermal irritations

Reduced risk of dental caries

Which of the following is NOT a problem associated with the loss of enamel and dentin?

Pain from thermal or osmotic irritations

Dentin discoloration from food stains

Improved structural integrity of the tooth (correct)

Increased susceptibility to bacterial action

What is a characteristic of lesions involving dentin?

They often leave dentin with irregular shapes (correct)

They typically have a uniform shape

They do not affect the dentin's structure

They enhance the dentin's mechanical properties

Which property is NOT required for lining and cement materials?

Permanent adhesion to the tooth Signup and view all the answers

Why are lining materials used in cavity preparations?

To compensate for the lost aesthetics and protect the pulp Signup and view all the answers

What type of environmental exposures may patients experience due to loss of protective enamel?

Thermal and chemical irritations Signup and view all the answers

What could lead to mechanical failure in teeth with irregular dentin shapes?

Inconsistent loading patterns during chewing Signup and view all the answers

Which property ensures that lining materials do not react adversely with the tooth?

Chemical neutrality Signup and view all the answers

What is the primary purpose of calcium hydroxide being present in excess in the mix?

To act as a continuous source of calcium and hydroxide ions Signup and view all the answers

Which method is used to mix the cement to minimize air bubbles?

Uni-directional rotational motion Signup and view all the answers

What should be ensured about the cavity before inserting cement?

It should be dry without being desiccated. Signup and view all the answers

What happens to the cement when it comes into contact with the moist dentin surface?

It sets quickly. Signup and view all the answers

What must be maintained between the cement and the cavity margin after application?

At least a 1mm cement-free zone Signup and view all the answers

What is the primary component that causes light-cured calcium hydroxide cement to harden?

Light polymerization of the resin component Signup and view all the answers

Which instrument is NOT mentioned as a tool for applying the cement?

Syringe applicator Signup and view all the answers

What is the composition of light-cured calcium hydroxide cement?

One-paste system with resin and particles Signup and view all the answers

What is one advantage of using the resin component in dental liners?

It ensures reliable chemical bonding with resin composites. Signup and view all the answers

Which property does Mineral Trioxide Aggregate (MTA) NOT possess?

Insolubility in oral fluids Signup and view all the answers

What is a notable disadvantage of using MTA?

It can darken the tooth due to iron content. Signup and view all the answers

How does MTA compare to calcium hydroxide regarding the formation of a dentin bridge?

MTA promotes thicker dentin bridge formation. Signup and view all the answers

What is a significant property of MTA that improves its effectiveness?

Its ability to aid in the release of bioactive dentin matrix proteins. Signup and view all the answers

What disadvantage do resin liners have related to pharmacological effects?

They do not allow leaching of calcium hydroxide necessary for pulp medication. Signup and view all the answers

What is the approximate setting time for MTA?

2 hours and 45 minutes Signup and view all the answers

What is the primary characteristic of solution liners?

They rely on evaporation for hardening. Signup and view all the answers

Which thickness range defines thick liners?

200-1000 µm Signup and view all the answers

What advantage does MTA provide over conventional materials like calcium hydroxide?

Less necrosis of pulpal tissue. Signup and view all the answers

What percentage of dentin surface coverage can a single coat of varnish achieve?

50% Signup and view all the answers

Which component is primarily found in solution liners?

Copal resin Signup and view all the answers

What is a key indication for using cavity varnishes?

To insulate against galvanic currents Signup and view all the answers

Which of the following is NOT a type of thick liner?

Solution Varnish Signup and view all the answers

What is a common clinical application of thin liners?

To seal cavity margins under amalgam restorations Signup and view all the answers

What happens to the resin in solution liners shortly after application?

It evaporates to leave a film. Signup and view all the answers

What is the preferred method for mixing cement to manage heat dissipation?

Using a large area with a long bladed spatula Signup and view all the answers

Why should a cavity varnish be used under the cement?

For chemical pulp protection Signup and view all the answers

What is one of the main benefits of resin-reinforced ZOE cement?

It has a reduced mixing time Signup and view all the answers

What is the consistency of the base created with the cement?

Heavy and putty-like Signup and view all the answers

What is the primary indication for using polycarboxylate cement?

Under metallic restorations for protection Signup and view all the answers

How should the cement powder be measured before mixing?

Divided systematically into halves and quarters Signup and view all the answers

What type of cement is modified by the incorporation of smaller powder particles?

Resin-reinforced ZOE cement Signup and view all the answers

What is a recommended action before the application of cement in the cavity?

Clean and dry the cavity without desiccation Signup and view all the answers

Study Notes

Loss of Enamel and Dentin

Loss of enamel or dentin reduces tooth protection and increases vulnerability to irritations.
Dentin-pulp system exposure can lead to pain and conditions like dental caries or pulpitis.
Enamel loss allows chromogenic bacteria and food stains to discolor dentin, affecting aesthetics.
Irregular-shaped lesions may cause stress concentrations, leading to mechanical failure of the tooth.

Restoration and Protection

Permanent restoration materials often fail to fully restore lost protective functions of enamel and dentin.
Lining materials are essential for:
- Providing thermal, chemical, electrical, and biological protection.
- Medicated pulp protection and aesthetic compensation.

Required Properties for Lining Materials

Compatibility with tooth structure and restorative materials.
Ease of application and sealing ability for dentinal tubules.
Sufficient working time and appropriate thickness (thin films: 1-50 µm; thick liners: 200-1000 µm).

Thin Liners

Solution liners (varnishes, 2-5 µm) rely on non-aqueous solvents for evaporation-based hardening.
Example composition includes copal resin dissolved in volatile solvents.
Clinical application involves a thin coat, often requiring a second layer for better coverage (80-85%).

Indications for Thin Liners

Applied under amalgam restorations for initial cavity sealing and electric insulation from currents.
Prevents cement acidity from damaging the pulp when using zinc phosphate cement.

Calcium Hydroxide Cements

Two types: Hard setting and Light-Cured.
Light-Cured variants enhance working time and bonding reliability but lack leachable calcium hydroxide effects.

Mineral Trioxide Aggregate (MTA)

MTA is a hydraulic Portland cement with calcium oxides, known for:
- Antibacterial properties and high pH.
- Superior dentin bridge formation compared to calcium hydroxide.
Limitations include prolonged setting time (approximately 2 hours and 45 minutes) and high cost.

Handling and Use of MTA

Cavity must be clean and properly isolated; a cavity varnish is recommended for chemical protection.
Mixing MTA involves careful portioning and methodical combining to manage exothermic reactions.
Placement with a condenser is crucial to ensure effective application; excess cement should be removed before setting.

Resin-Reinforced ZOE Cement

Modified with resins and smaller powder particles to enhance strength and speed of setting.
Commonly used as a base under metallic restorations and as a long-term temporary filling.

Polycarboxylate Cement

Composed of zinc oxide powder and polyacrylic acid liquid, providing chemical adhesion properties beneficial in dental applications.

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Description

Explore the impact of enamel and dentin loss on tooth protection and the subsequent risks posed to the dentin-pulp system. This quiz discusses various problems associated with enamel and dentin loss, including exposure to thermal and osmotic stimuli.