Dental Instrument Grasps

Instrument Grasps

• Modified Pen Grasp is most commonly used.
• This grasp provides the greatest delicacy of touch.
• It is similar to the pen grasp, however the pad of the middle finger is on the instrument handle instead of underneath.
• Positioning enhances instrument control via a "triangle of forces" or "tripod effect".
• Most commonly used for mandibular teeth.
• Palm faces away from the operator.
• Stabilizes the instrument and allows the middle finger to help push the instrument down.
• Inverted Pen Grasp involves the same finger positions as the modified pen grasp.
• The hand is rotated so that the palm faces towards the operator.
• This grasp is most commonly used for preparing a tooth in the lingual aspect of maxillary anterior and occlusal surface of maxillary posterior teeth.
• Palm and Thumb Grasp is similar to holding a knife for peeling an apple.
• The instrument is grasped near its working end, bracing the thumb against the teeth for control.
• The shaft of the instrument is placed on the palm of the hand and grasped by the four fingers, while the thumb controls movements and rests on an adjacent tooth of the same arch.
• Palm Grasp is used for holding surgical instruments.
• Thrust action achieved by forcing the instrument away from the thumb tip.
• Has limited use, mainly during operations on maxillary anterior teeth.
• Used for holding a handpiece while cutting incisal retention for a class III preparation in maxillary incisor.
• Modified Palm and Thumb Grasp is like the palm grasp.
• The pads of all four fingers press the handle against the palm, pad, and first joint of the thumb.
• The thumb tip rests on the tooth being prepared or an adjacent tooth.
• It provides more control to avoid slipping of the instrument.
• This grasp is commonly used in maxillary anterior teeth.

Finger Rests

• Finger rests stabilize the hand and instrument by providing a firm rest during operative procedures.
• Finger rests can be intraoral or extraoral.

Intraoral Finger Rests

• Conventional: Finger rest is near or adjacent to the working tooth.
• Cross-arch: Finger rest is achieved from a tooth on the opposite side but in the same arch.
• Opposite Arch: Finger rest is achieved from a tooth in the opposite arch.
• Finger on Finger: Rest is achieved from the index finger or thumb of the non-operating hand.

Extraoral Finger Rest

• Used mostly for maxillary posterior teeth.
• Palm Up: Rest is obtained by resting the back of the middle and fourth fingers on the lateral aspect of the mandible on the right side of the face.
• Palm Down: Rest is obtained by resting the front surface of the middle and fourth fingers on the lateral aspect of the mandible on the left side of the face.

Methods of Instrument Use

• Instruments are effectively used from the bevel side to the non-bevel side.
• Hold the instrument to allow the cutting edge to remove any unsupported enamel from the preparation walls.
• Always hold the instrument parallel to the wall being worked upon.
• Holding at an incorrect angle may increase cutting but cause damage or fracture of the tooth.
• For the buccal wall, use one side of the instrument; for the lingual wall, use the other side.

Sharpening of Hand Instruments

Goals

• Produce a functionally sharp edge.
• Maintain the contour (shape) of instrument.
• Maintain the life of instrument.

Advantages

• Improved efficiency
• Improved tactile sensations
• Less pressure and force
• Improved instrument control
• Minimized patient discomfort
• Less treatment time

Principles

• Select the appropriate type of stone for the instrument.
• The instrument should be clean and sterile before sharpening.
• Establish the correct angle between the stone and instrument surface based on the design.
• Lubricate the stone during sharpening to reduce clogging and heat.
• Maintain a stable and firm grip on both the instrument and stone during sharpening.
• Maintain proper angulation throughout sharpening strokes.
• Sharpen with light strokes or pressure, avoiding excessive force.
• After sharpening, check the cutting edge for wire edges.
• Remove wire edges (unsupported metal fragments extending beyond the cutting edge).
• Resterilize the sharpened instruments.