Cavity Preparation Fundamentals

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Questions and Answers

Which retentive feature is primarily used in molars to enhance resistance to displacement of restorations?

Intra-Radicular Posts

Dove-tail lock (correct)

Dentin Pins

Reverse Bevel

What is the recommended depth of a slot used as a retentive groove in dentin?

0.5mm

0.6mm (correct)

0.4mm

0.7mm

Which factor does NOT influence the selection of retention features in cavity preparation?

Size of the cavity

Site of the cavity

Patient’s age (correct)

Type of restoration

What characterizes the Mortise Box or Modified Box Form in cavity preparation?

It neutralizes functional stresses with right angle walls. (D) Signup and view all the answers

What type of dental restoration typically requires more retention due to occlusal stresses?

Class II (A) Signup and view all the answers

What is the role of axial coves prepared with No ¼ bur in dentin?

To provide additional retention. (B) Signup and view all the answers

Acid etching is used primarily for which type of restoration material?

Resin composite (D) Signup and view all the answers

What is a potential consequence of inadequate retention features in cavity preparation?

Fracture of the tooth or restoration. (D) Signup and view all the answers

What is the principal mechanism of retention in restorative dentistry?

Macro-Mechanical Retention (A) Signup and view all the answers

Which of the following describes micro-mechanical retention?

It forms microscopic resin tags from acid etching. (B) Signup and view all the answers

What feature primarily prevents axial displacement of restorations?

Occlusal convergence of cavity walls (A) Signup and view all the answers

Which retention feature allows for a more conservative approach in tooth restorations?

Acid etching (A) Signup and view all the answers

What is the purpose of proximal axial grooves in cavity preparations?

To stabilize the restoration against lateral forces (A) Signup and view all the answers

Which statement is true regarding dentin pins used in restorations?

They can be cemented or threaded and parallel or non-parallel. (D) Signup and view all the answers

What does lateral retention in restorations aim to prevent?

Lateral movement of the restoration (B) Signup and view all the answers

What is the primary role of dentin ledges in cavity preparations?

To prevent pulpward movement of the restoration (D) Signup and view all the answers

What is the primary purpose of cavity preparation?

To create a solid foundation for restoration (B) Signup and view all the answers

What is considered a thermal irritation during cavity preparation?

Cutting at high speed without coolant (B) Signup and view all the answers

Which of the following describes direct restorations?

Restorations applied directly in the patient's mouth during the same visit (A) Signup and view all the answers

What should be limited to ensure protection against mechanical irritation during cavity preparation?

The depth of the cavity being prepared (C) Signup and view all the answers

What is the aim of the 'Thermal Tolerance Zone' (TTZ) in cavity preparation?

To maintain the health of dentin and pulp under cutting conditions (B) Signup and view all the answers

What type of irritation may occur from the use of certain cleaning agents during cavity preparation?

Chemical irritation (C) Signup and view all the answers

Which practice can help prevent the occurrence of caries?

Regular flossing and fluoride applications (B) Signup and view all the answers

What is essential for maintaining a sterile environment during cavity preparation?

Sterilization of instruments and use of rubber dams (C) Signup and view all the answers

Which type of restoration is not categorized under direct restorations?

Cast Gold (D) Signup and view all the answers

What is a key characteristic of amalgam restorations compared to composite restorations?

They undergo corrosion. (B) Signup and view all the answers

What is the first step in cavity preparation?

Obtaining of the outline form (B) Signup and view all the answers

What distinguishes composite restorations from amalgam restorations?

They have a tooth-colored appearance. (C) Signup and view all the answers

Which step must be completed before obtaining resistance and retention forms in the case of deep carious lesions?

Removal of the remaining carious dentin (C) Signup and view all the answers

Which step of cavity preparation involves shaping the internal form of the cavity?

Obtaining of the outline form (C) Signup and view all the answers

What is a notable disadvantage of amalgam restorations?

Corrosion (C) Signup and view all the answers

What does the term 'convenience form' refer to in cavity preparation?

The internal shape for fitting restoration tools (C) Signup and view all the answers

What is the primary purpose of the inverted truncated cone form in cavity preparation?

To provide retention through undercuts while preventing wedging action (D) Signup and view all the answers

Which of the following describes the convenience form in cavity preparation?

Extending the cavity outline for better manipulation and visibility (C) Signup and view all the answers

How do proximal axial locks aid in cavity preparation?

By providing additional retention and preventing isthmus fractures (D) Signup and view all the answers

Which of the following tools is emphasized for a conservative approach in cavity preparation?

Micro-sized burs (C) Signup and view all the answers

What does the 'conservative approach' in cavity preparation advocate for?

Minimum cutting while effectively restoring defects (D) Signup and view all the answers

What is one benefit of using fiber-optic handpieces during cavity preparation?

They improve visibility and illumination for precise work (A) Signup and view all the answers

Which feature is NOT associated with the resistance form in cavity preparation?

Eliminating all forms of undercuts (B) Signup and view all the answers

What is the desired outcome of sweeping curves in cavity preparation?

To allow easier restoration of anatomy (B) Signup and view all the answers

What type of dentin must be removed to avoid further bacterial invasion in deep cavities?

Infected dentin (C) Signup and view all the answers

Which type of dentin can potentially be remineralized and saved?

Affected dentin (B) Signup and view all the answers

What is the goal of the complete caries removal strategy established by G.V. Black?

To ensure a hard sound dentin floor (C) Signup and view all the answers

In which situation should hard but discolored dentin be carefully left in place?

In posterior teeth due to low visibility (C) Signup and view all the answers

What happens to dentin when there is significant bacterial invasion?

The organic matrix is destroyed. (A) Signup and view all the answers

Which treatment approach involves leaving affected dentin intact while removing only the infected dentin?

Partial caries removal (C) Signup and view all the answers

What defines infected dentin in terms of consistency and condition?

Soft and infected with bacteria (D) Signup and view all the answers

What is the role of indirect pulp capping material in cavity preparation using the partial caries removal strategy?

To allow pulp to lay down tertiary dentin (B) Signup and view all the answers

Study Notes

Fundamentals of Cavity Preparation

Fundamentals: Basic principles, rules, and laws forming the groundwork of a system.
Standardization: Process of conforming something to a standard.
Cavity: Defect in hard tooth structure caused by dental caries.
Prepared Cavity: Bio-mechanical foundation for a restoration.
Direct Restorations: Applied directly in the patient's mouth during cavity preparation.
Indirect Restorations: Fabricated outside the mouth (lab), then cemented to the prepared cavity.

I- Protection of Dentin and Pulp

Mechanical Irritation:
- Excessive enamel cutting exposes more dentin, weakening the remaining tooth structure.
- Overcutting dentin (depth) weakens the protective dentin bridge, potentially injuring the pulp.
- Unnecessary pressure on the base of a deep cavity can injure the pulp.

Thermal Irritation

Maintaining temperatures within the physiological tolerance zone (85-132°F / 29-56°C) of dentin-pulp organ during procedures.
Minimizing frictional heat by decreasing pressure area and cutting time.
Using high-efficiency cutting tools and air-water spray during procedures.

Chemical Irritation

Using chemical agents (e.g. phenolic agents) during cleaning can cause chemical irritation.
Acidic dentin conditioners used with bonded restorations can cause chemical irritation.

Bacterial Irritation

Remove bacteria causing caries during preparation.
Use antimicrobial agents (e.g., chlorhexidine) to prevent cross-infections.
Sterilize instruments, burs, and armamentarium to avoid cross-infection.
Use rubber dam to isolate the operative area.

II- Control of Caries

Prevent Caries Recurrence:
- Prevent food accumulation in pits and fissures by preparing or sealing them.
- Remove weak or undermined enamel to prevent fracture.
III. Protection of Investing Tissues and Adjacent Teeth:
- Avoid improper subgingival extensions.
- Maintain a smooth, caries-free gingival margin.
- Protect adjacent teeth during proximal preparations with metal bands.
- Avoid injuring gingival tissues during procedures.

B- Mechanical Fundamentals

Preserve the structural integrity of both the tooth and restoration (prevent fracture).
Retain the restoration within the cavity (prevent displacement).
Design cavities to maximize tooth structure conservation.

C- Esthetic Fundamentals

Use symmetrical cavity outlines with smooth, sweeping curves.
Minimize visible restoration areas using conservative designs.
Eliminate discolored areas of enamel or dentin, especially in anterior cavities.

Conservative approach in Operative Dentistry

Minimally invasive approach focused on detecting, diagnosing, and removing only the damaged tooth structure while preserving healthy structure.
Emphasize concepts of prevention and remineralization during restorative procedures.
- Aim to preserve tooth and masticatory system integrity.
- Emphasize prevention as the main goal now, rather than extension.
- 'Sealing for prevention': examples are pit and fissure sealants.
Advantages of conservative cavity design:
- Preserves healthy tooth structure.
- Decreases irritation of dentin-pulp complex, and investing tissues
- Reduces fractured teeth and/or restorations
- Shorter, simpler treatments
- Simpler standardized procedures

Restorations

Amalgam is brittle and non-bonded to tooth structures and suffers from corrosion and aesthetic issues.
Composite restoration is more resilient than amalgam/bonded and esthetic/tooth colored.

Cavity Preparation - STEPS

Step 1: Outline form: Include all carious enamel and dentin. Include pits and fissures deeper than one-third of enamel. Remove weak enamel.
Step 2: Resistance & retention form: Design the cavity to withstand the stresses of mastication. Increase depth, smooth preparation.
Step 3: Convenience form: Make cavity accessible for work. Make walls smooth
Step 4: Remove remaining carious dentin: Remove soft and infected damaged dentin.
Step 5: Finish cavity walls and margins: Remove undermined enamel to ensure even surface for proper adaptation with restorative materials. Correctly shape walls. Smooth walls.
Step 6: Toilet of the cavity: Clean and dry the cavity and remove debris so restorative material can fit securely and last

5. Finishing of Cavity Walls and Margins

Remove remaining undermined enamel.
Adjust the cavo-surface angle inclination.
Ensure the walls have correct inclination for adaptation.
Make smooth walls for proper adaptation.
Smooth rounding of line and point angles.
Finishing can be accomplished with hand instruments

6. Toilet of the Cavity

All procedures to prepare the cavity to receive the restorative material.
No medicaments to be used during the procedure.
Cavity must be clean and completely dry
Cavity lined to provide pulp protection.
Objectives include removing bacteria, debris (and saliva), remnants of dentin chips, and temporary restoration materials. The goal is to create a healthy environment for the new restoration and minimize the chance of recurrence of decay.

Techniques for Caries Removal

Manual Excavation (soft carious dentin) by hand instruments
Mechanical Excavation round Burs (harder carious dentin)
Air Abrasion: tiny aluminum oxide particles, compressed air
Laser Debridement: using thermal energy, water coolant
Chemo-Mechanical Debridement (combination of acids and sodium hypochlorite)
Enzymes: those that dissolve carious parts (e.g., Pronase)

Factors Affecting Cavity Outline

Occlusal Cavities: Caries extent, occlusal table anatomy (upper/lower, individual tooth), unusual anatomy, steep cusps. Important locations for contacts are contact-free or non-stress-bearing areas
Proximal Cavities: Size/position of contact area, width of embrasures, position/health of gingival tissues
Posterior Teeth (Class II): The intersection of the occlusal cavity and the proximal surface, including Ingerham´s lines

Factors Controlling Selection of Retention Features

Size and amount of tooth structure remaining
Missing Walls: The greater the missing walls, the greater the need for retention
Cavity Site & Occlusal Stress: Locations and stress factors (e.g., class II vs class V)
Restoration Type (e.g., composite vs. amalgam affect retention needs).
Pulp Vitality (e.g., vital pulp vs. non-vital pulp affect restorative considerations)
Esthetic Requirements: Important for selecting location and shape of retention features

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Description

This quiz covers the essential principles of cavity preparation in dentistry. It includes topics on the protection of dentin and pulp, standardization in procedures, and distinctions between direct and indirect restorations. Test your knowledge on the mechanical and thermal irritations associated with cavity preparation.