Instruments

A successful restion depends mainly on a proper cavity preparation which in turn is based on the use of proper instruments. The importance of instrument set up and the usage of various instruments are discussed here.

1. What are the abrading tools used in dentistry?

The abrading tools are the rotating instruments that can rotate in either direction and its surface is impregnated with bits of hard substances like diamond or sand. The particle size varies based on whether it is used for reducing hard enamel or for polishing soft plastic.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 31

2. Why are sharp corners or rough scratchy surfaces unacceptable in the oral cavity?

Sharp corners and irregularities in the oral cavity can irritate soft tissues or the tongue. These irregularities tend to trap debris leading to plaque accumulation, stains and corrosion on restorations.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 49

3. How is the greatest control achieved in a hand cutting instrument?

Greatest control of a hand cutting instrument is achieved in an instrument with a large blade, minimum number of bends and with a cutting edge in direct axial alignment with the blade.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 52

4. Why is undermining of enamel damaging to the tooth?

The dentin provides a semi elastic base to which enamel is securely attached. When caries or a dental bur removes the underlying dentin, the enamel will remain unsupported and any pressure on it will result in fracture. So it is always necessary to cut the unsupported enamel and make the edges rest upon solid, healthy dentin.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 74

5. Why are coolants necessary during cutting of teeth?

A coolant applied to the bur reduces the heat generated during cutting and also it aids in the removal of debris.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 78

6. What are the types of coolants available?

Air, water and waterspray are the types of coolants available which are effective in reducing the temperature during cutting.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 78

7. What is the sequela if coolants are not used during cutting?

During cutting, heat is generated by the bur which is absorbed by the tooth. If the temperature of the tooth becomes too great, irreversible damage to the pulp may occur.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 78,79

8. What are the possible deleterious effects of restorative procedures upon the dentin?

• Heat generated bu the cutting action of burs.

• Excessive dehydration during cutting.

• Transfer of heat through metallic restorations which are thermal conductors.

• Application of any restorative material that provides a toxic environment to the cut surface.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 81

9. How are the effects on the dentin minimized during operative procedures?

By avoiding

• prolonged application of blasts of warm air.

• Excessive tooth cutting without suitable coolants.

• Avoiding placement of irritating filling materials on the exposed dentin surfaces without using insulators or liners.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 81

10. What are the two basic instrument grasps?

The two basic instrument grasps are

• Pen grasp and

• Palm grasp.

• The pen grasp provides more flexibility of movement with less power and palm grasp provides only limited movement with controlled power.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 100

11. How is the instrument held in a correct pen grasp?

The instrument is pinched between the thumb and forefinger. The middle finger engages the enamel with care being taken that the shaft does not rest against the side of the finger.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 104

12. What is modified pen grasp?

In modified pen grasp, the wrist is straight and the index finger is curved, the instrument is held like a spoon.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 106

13. What is the role of mouth mirrors in operative procedures?

The mouth mirror enables the operator to see in obscure areas of the mouth. It reflects the operating light and illuminates the particular region providing vision to the operator. It also reflects the tongue and cheek for insertion of cotton rolls or generally for gaining access to the area.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 110

14. Why are front surface mouth mirrors preferred than the regular ones?

The front surface mirrors are silvered on the outer surface of the glass. Though they are most susceptible to scratching, they are preferred over the regular type because they do not produce double images.

Ref: Lloyd Baum,Ralph W.Phillips,Melvin R.Lund.Textbook of Operative Dentistry.W.B.Saunders company;1985; 112