DH Theory 1 L2

Study Notes

Instrumentation Fundamentals: Modified Pen Grasp & Dental Mirror

The modified pen grasp is the recommended method for holding periodontal instruments.
It's a sensitive, stable, and strong grasp due to a tripod effect from the thumb, index, and middle fingers.
The grasp needs continual re-establishment on the instrument.
To use the modified pen grasp correctly, identify the instrument parts: handle, shank, and working end.
The modified pen grasp is more precise than a writing grasp.
Successful instrumentation depends on precision in finger placement.
Specific finger placement is crucial for technique.
Incorrect finger placement (e.g., index and thumb not positioned opposite each other on the handle) or overlapping fingers decreases control.
A "U-shaped" grasp (index and thumb curving inward) is also incorrect, making it difficult to control the instrument and lifting finger pads off the handle.
The instrument handle should rest against the hand for stability.
Holding the handle away from the hand makes the grasp weak and unstable.
The middle finger should rest lightly on the shank, allowing for the feeling of vibrations from the working end (tactile feedback).
The middle finger pad should rest against (or slightly overlap) the ring finger for stability.
The ring finger should be positioned ahead of the other fingers to properly support the grasp; it rests on the tooth for a stable fulcrum.
The ring finger should be in a straight manner and not curved or limp, providing stability for better control of the instrument.
The index, middle, and ring fingers should ideally contact each other at one point for solid stability and strength in the grasp.
The little finger plays no role in the grasp.
Correct finger placement includes the index and thumb opposite each other near the handle-shank junction, the middle finger resting lightly on the shank on one side and resting against the ring finger on the other side, and the ring finger positioned on the tooth.
Incorrect split fulcrum grasp (lack of contact between the middle and ring fingers) leads to a weak grasp and increased muscle stress in the hand.

Dental Mirror

The dental mirror's working end has a reflecting surface.
Common mirror types include front surface, concave, and plane (flat).
A front surface mirror creates a clear image with no distortion and is frequently used for its good quality.
A concave mirror produces a magnified image but causes image distortion.
A plane mirror creates a double image (ghost image) and is less preferable for its distracting double image.
Dental mirrors are used in procedures for:
- Indirect vision.
- Retraction.
- Indirect illumination.
- Transillumination.
To prevent fogging, the mirror's surface should be moistened.

Uses of Dental Mirror

Indirect vision allows viewing surfaces not directly visible.
Retraction holds cheeks, lips, or tongue out of the way.
Indirect illumination reflects light onto the oral structures.
Transillumination directs light through anterior teeth to detect hidden decay.
Correct light position for transillumination is at the 12 o'clock position (perpendicular to the tooth).
Correct mirror positioning in transillumination means the mirror should be behind the anterior teeth, with its reflective surface parallel to the teeth' lingual surfaces.
Observing the tooth in the mirror, rather than the mirror itself, produces a clear view of the tooth (with reflected light).
Transillumination doesn't easily reveal shadows on healthy teeth because interproximal decay is usually not present.
Transillumination finds hidden decay in anterior teeth as shadows.
Anterior teeth are fine enough to permit light passage.
Posterior teeth are too thick for light to pass through and are not ideal for transillumination.