Cavity Preparation in Conservative Dentistry

IMPORTANT VIVA QUESTIONS CONTD…

Q1. What is meant by establishing outline form?

Ans.  Establishing outline form means:

• Placing the preparation margins in the positions they will occupy in the final preparation for finishing enamel walls and margins
• Preparing an initial depth of 0.2-0.8mm pulpally of the DEJ

Q2. What are the factors determining the outline form?

Ans.  

1. Extent of carious lesion
2. Faulty old restoration
3. Aesthetic consideration
4. Occlusal conditioning such as stress bearing areas
5. Contact with adjacent tooth and its contour
6. Desired cavosurface margin for the specified restoration

Q3. What is retention form?

Ans. Retention form is the shape or form of the cavity preparation that resists displacement of removal of the restoration by tipping or lifting forces.

Q4. What are the auxiliary means of retention?

Ans.

1. Grooves
2. Internal boxes
3. Posts
4. Pins
5. Acid conditioning/acid etching
6. Luting cements

Q5. What are primary retention form features for amalgam?

Ans. 

1) Inverted truncated form – pulpo-occlusally convergent preparation

2) Undercuts

3) Dovetail

Q6. What are the various retention types for different restoration?

Ans. 

1) Amalgam: Mechanical retention by the design of the cavity

2) Composite: Micromechanical retention aided by resin tags in the micro pores created by acid-etching

3) Glass ionomer cement: Chemical adhesion

4) Indirect restoration: Tensofriction

Q7. What is resistance form?

Ans. Resistance form is the shape of the cavity that enables both the restoration and the tooth to withstand masticatory forces delivered principally along the long axis of the tooth without fracture.

Q8. What are the resistance form features?

Ans.

1) Box shape (mortise) of the cavity and flat pulpal floor perpendicular to masticatory forces

2) Roundening of line angles to reduce stress concentration

3) Sufficient thickness of restorative material to prevent its fracture under load

4) Preservation of cusp, ridge areas and walls with sufficient dentin support

5) Capping of weak cusps and inclusion of weakened tooth structure within the restoration.

Q9. What is convenience form?

Ans. It is defined as the shape or modification done to the basic tooth preparation to facilitate proper instrumentation and insertion of the restorative material.

Q10. What is the width of the gingival seat mesiodistally?

Ans. 0.5mm-0.6mm into dentin and 0.2-0.3mm into enamel

Q11. What is the width of gingival seat?

Ans. Its is 0.7-0.8mm, 0.5mm into dentin and 0.2-0.3mm into enamel

Q12. Define dental caries?

Ans. Dental caries is defined as an irreversible microbial disease of the calcified tissues of teeth, characterize by dimeralisation of the inorganic portion and destruction of organic substance of the teeth.

Q13. What are types of dental caries?

Ans.

i) Primary, secondary, residual caries based on the time of formation

ii) Pit and fissure, smooth surface caries based on area of occurrence

iii) Forward caries, backward caries based on progression

iv) Acute caries, chronic caries based on rate of spread

Q14. What are instruments and equipment?

Ans.

🔹Instruments are small, handheld and used for various procedures in treating a patient, e.g. mouth mirrors, probes, tweezers, condensers. 

🔹Equipments are large and are the accessories for treating a patient, e.g. dental unit, operating stool, dental chair, X-ray unit, amalgamator.

Q15. Classify instruments.

Ans. Instruments are broadly classified as:

🔹Hand instruments: instruments that are manually used

🔹Rotary instruments: instruments that are engine driven

• V Black’s Classification
• Marzouk’s Classification
• Sturdevant’s Classification