Modified Palm and Thumb Grasp Quiz & Flashcards

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Questions and Answers

What is the primary consequence of using a dull hand cutting instrument during an operative procedure?

Loss of control and increased pain (correct)
Reduced time for the procedure
Enhanced precision in tooth preparation
Improved control over the instrument

What is the purpose of using a stationary sharpening stone, such as an Arkansas stone?

To reduce the quality of tooth preparation
To sharpen the instrument's cutting edge (correct)
To move the instrument at high speed
To sharpen the instrument quickly

Which grasp is used for lingual and labial surfaces of upper anterior teeth?

Inverted pen grasp
Modified pen grasp (correct)
Modified palm and thumb
Palm and thumb

What is the importance of rest and guard in grasping hand cutting instruments?

It provides proper control and stability (B) Signup and view all the answers

What is the advantage of using a mechanical sharpener?

It is easier and less time-consuming (C) Signup and view all the answers

What is the primary consequence of prolonged time for an operative procedure?

Increased risk of complications (D) Signup and view all the answers

How many grasps are used with hand cutting instruments?

4 (A) Signup and view all the answers

What is the function of the thumb in the inverted pen grasp?

To be free of the instrument and rest on the nearby tooth (D) Signup and view all the answers

What is the primary purpose of sharpening hand cutting instruments?

To maintain the cutting edge and prevent loss of control (D) Signup and view all the answers

What is the primary function of an ordinary hatchet in tooth preparation?

Sharpening internal line angles in anterior teeth (A) Signup and view all the answers

What is the characteristic of the primary cutting edge of a hoe excavator?

Perpendicular to the axis of the handle (A) Signup and view all the answers

What is the specific use of an angle former in dentin preparation?

Sharpening line angles and creating retentive features (D) Signup and view all the answers

What is the specific use of a spoon excavator?

Removing caries and carving amalgam or direct wax patterns (D) Signup and view all the answers

What is the characteristic of the cutting edge of an ordinary hatchet?

On the same plane as the handle (D) Signup and view all the answers

In which type of preparations is a hoe excavator commonly used?

Class III and V preparations (A) Signup and view all the answers

What is the function of an angle former in enamel margins?

Placing a bevel on enamel margins (D) Signup and view all the answers

What is the characteristic of an angle former?

Mon-angled with the primary cutting edge at an angle (other than 90 degrees) to the blade (A) Signup and view all the answers

What is the availability of angle formers?

Available in pairs (right and left) (B) Signup and view all the answers

What is the purpose of a GMT instrument?

To produce a proper bevel on gingival enamel margins (B) Signup and view all the answers

What is the characteristic of a chisel with a distal bevel?

Designed to plane a wall that faces the blade's inside surface (B) Signup and view all the answers

What is unique about the GMT instrument's cutting edge?

It is at an angle to the blade (B) Signup and view all the answers

What is the purpose of an enamel hatchet?

To cut and plane enamel (B) Signup and view all the answers

What is the characteristic of a chisel with a mesial bevel?

Designed to plane a wall that faces the blade's outside surface (A) Signup and view all the answers

What is the characteristic of a GMT instrument?

Has a curved blade (D) Signup and view all the answers

What is the purpose of a chisel in direct gold restorations?

To plane walls in direct gold restorations (B) Signup and view all the answers

What is the characteristic of the blade of an enamel hatchet?

It is beveled on one side (A) Signup and view all the answers

What is the purpose of a GMT instrument in preparing proximo-occlusal preparations?

To produce a proper bevel on gingival enamel margins (A) Signup and view all the answers

What is the primary function of a negative rake angle in bur design?

To increase the tool life by reducing fractures of the cutting edge (A) Signup and view all the answers

What is the maximum displacement from the central axis allowed for bur eccentricity?

0.025 mm (B) Signup and view all the answers

What is the purpose of crosscuts on fissure burs?

To improve cutting effectiveness at low speeds (C) Signup and view all the answers

What is the main disadvantage of carbide burs?

Brittleness (B) Signup and view all the answers

What is the purpose of bur locking or shank design?

To hold the bur securely in the handpiece (D) Signup and view all the answers

What is the main disadvantage of steel burs?

Rust (A) Signup and view all the answers

What is the relationship between rake angle and cutting edge?

A negative rake angle decreases the cutting edge angle (A) Signup and view all the answers

What is the effect of eccentricity or run-out on cutting efficiency?

It reduces the cutting efficiency (A) Signup and view all the answers

What is the purpose of measuring concentricity in bur design?

To measure the symmetry of the bur head (D) Signup and view all the answers

What is the difference between cutting effectiveness and cutting efficiency?

Cutting effectiveness measures the rate of tooth structure removal, while cutting efficiency measures the percentage of energy producing cutting (B) Signup and view all the answers

What is the primary advantage of using high speed hand pieces in operative dentistry?

Reduced operating time and improved patient comfort (A) Signup and view all the answers

What is the primary function of the blades in a dental cutting tool?

To produce a cutting action by chipping (A) Signup and view all the answers

What is the characteristic of diamond points that makes them more effective for extra-coronal tooth preparations?

Their large surface area of contact with the tooth (A) Signup and view all the answers

What is the primary benefit of using carbide burs in operative dentistry?

They are better suited for end cutting and produce lower heat generation (B) Signup and view all the answers

What is the primary consideration when selecting a material for a dental cutting tool?

The tool's durability and resistance to wear (A) Signup and view all the answers

What is the purpose of the shank design in a dental cutting tool?

To enable the tool to be securely locked into the hand piece (C) Signup and view all the answers

What is the primary effect of eccentricity in a dental cutting tool?

It increases the vibration and pressure during cutting (A) Signup and view all the answers

What is the primary function of the rake angle in a dental cutting tool?

To determine the direction of the cutting action (B) Signup and view all the answers

What is the primary advantage of using abrasive stones in operative dentistry?

They remove tooth structure through abrasion (C) Signup and view all the answers

What is the primary characteristic of the cutting edge of a carbide bur?

It is better suited for end cutting and produces lower heat generation (B) Signup and view all the answers

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Study Notes

Importance of Sharpening Hand Cutting Instruments

Dull instruments cause loss of control, more pain, prolonged operative procedure, and reduced quality and precision of tooth preparation.
Sharpening keeps the cutting edge sharp, ensuring efficiency and effectiveness in tooth preparation.

Methods of Sharpening Hand Cutting Instruments

Stationary sharpening stone (e.g., Arkansas stone, silicon carbide)
Mechanical sharpener (easier and less time-consuming)

Importance of Rest and Guard

Rest: the adjacent teeth act as a rest, providing support and stability during the procedure.
Guard: the thumb, index, and middle fingers contact the instrument, while the ring and little fingers rest on the adjacent teeth, ensuring proper control and precision.

Hand Instrument Grasps

Modified pen grasp: similar to holding a pen, with the thumb, index, and middle fingers contacting the instrument.
Inverted pen grasp: the handle is placed in the palm, and the thumb rests on the nearby tooth, used for lingual and labial surfaces of upper anterior teeth.
Modified palm and thumb grasp
Palm and thumb grasp

Types of Hand Cutting Instruments

Excavators:
Ordinary hatchets (bibeveled, for preparing retentive areas and sharpening internal line angles)
Hoes (primary cutting edge perpendicular to the axis of the handle, for planning tooth preparation walls and forming line angles)
Angle formers (mon-angled, for sharpening line angles and creating retentive features in dentin)
Spoon excavators (discoid or cleoid, for removing caries and carving amalgam or direct wax patterns)
Chisels:
Straight, curved, and bin-angle chisels (for cutting enamel)
Enamel hatchets (beveled on one side, for cutting and planning enamel)
Gingival margin trimmers (for rounding or beveling gingival enamel margins)

Rotary Instruments

Components of rotary system:
Source of power (electric driven or air driven)
Hand piece (low speed or high speed)
Cutting tool (dental bur or abrasive stone)
Advantages of high-speed hand pieces:
Faster removal of tooth structure with less pressure and vibration
Reduced operating time
Operator has better control and greater ease of operation
Instruments last longer
Patients are generally less apprehensive
Dental burs:
Carbide burs (better for end cutting, produce lower heat generation)
Diamond points (produce more friction, high heat generation, effective for extra-coronal tooth preparations and beveling enamel margins)
Abrasive tools (stones):
Metal blank + binder + abrasive particles
Cuts by abrasion

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Instruments for Tooth Preparation in Operative Dentistry

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