Module 10 - Movement and orientation to tooth surface

module 9 online textbook

What is periodontal instrumentation?

• Fine motor (psychomotor) skill

• Brain—body coordination between brain, nervous system, and muscles

• Requires repeated practice to master

Stages of psychomotor development

Observing

• Definition: Mental attention to steps of psychomotor skill

Ex: Reading step by step instruction, viewing clip or demonstration, before preclinicals

Imitating

• Definition: Attempting to copy the psychomotor skill

Ex: Attempting step by step instruction, movements not smooth or automatic, receives feedback, during preclinical

Practicing

• Definition: Attempting psychomotor skill over and over

Ex: Skill is practiced repeatedly, movements becoming smoother, preclinical and clinical

Adapting

• Definition: Fine tuning. Minor adjustments made to skill to perfect it.

Ex: Mentor needed to provide improvements or adjustments to perfect skill, last semester or quarter of clinic

Awkward movement —> Practice coordination —> Smoother —> Automatic/ perfect

Muscle memory

• Stored in brain, not muscles

• Repeated movements creates stronger neural pathway

Myelination

• Forming myelin sheath around nerves

• Allow nerve impulses to travel faster

More practice = more myelination = better performance

Expert musicians practice during childhood = more myelin density in brain region related to fine motor skills

Quality of practice

• Practice doesn’t make perfect

Poor practice

• Repeating mistakes builds muscle memory for mistakes

Good practice

• Repeating correct movements builds proper muscle memory

Automaticity

• Ability to perform psychomotor skill smooth, easily, without frustration

• Consistent practice and repetition

  • Movement becomes permanent only after repetition many times

  • No substitution for practice

Strategies that make psychomotor learning easier

Guidance

• Follow step by step instructions

• Recognize what correct skill performance looks like

Practice

• Slow at first and expect choppy movements

• Focus solely on skill you are practicing

• Delay gratification; tolerate short—term discomfort in order to achieve worthwhile goal

Feedback

• Obtain feedback so muscle memory is learning correct technique, not incorrect movements

Recognition self—asessment

• Recognize and contrast correct vs incorrect technique

• Good recognition = improved performance

• Visualize correct performance

Practice beyond “getting it right”

• Do frequent sustained practice

• Practice beyond

• Make each movement a permanent part of your brain

Motion activation

Muscle action used to move periodontal instrumnet’s working end across a tooth’s surface

Types of motion activation

1. Wrist rocking motion

• Strong, preferred, most common

2. Digital activation

• Weak, only used in special situations

Wrist rocking motion

• Hand, wrist, and arm move together as a unit for instrumentation stroke = rotating motion

• Used for calculus removal

Ex: Turning a doorknob

• Allows for maintaining neutral body posture

  • Shoulder level, upper arm vertical, forearm horizontal, less workload on wrist, hands and fingers

Advantages

• Intraoral fingers — stabilizes

• Reduce muscular load

• More hand control

• Less fatigue

• Uses large muscle of wrist and forearm instead of tiny finger muscles

Fulcrum during wrist rocking motion

• Fulcrum finger supports weight of hand

Throughout procedure:

• Fulcrum finger (ring) stays planted

• Acts as pivot point or brake for each stroke

Avoid: If instrument tip flies off the tooth after each stroke, fulcrum isn’t used properly.

Digital activation

Digital motion activation

• Moving the instrument by flexing the thumb, index, and middle fingers

Ex: Pulling something with fingertips

(Instead of using wrist — thumb, index, middle — do all the work)

Uses

• Physical strength not required

  • Example: Probes, explorer, ultrasonic scaler

• Use if movement is restricted in instrument areas (Ex: Multirooted teeth)

Why not use it all the time?

• Fingers fatigue quicker

• Small muscles = weaker

• Do not use digital activation for calculus removal

Rolling the instrument handle

• Turning the handle between thumb and index finger

Why?

• Maintain contact of working end as it moves around the curve of the tooth surface

Drive finger

• Thumb or index

• Used to turn the instrument

Whatever finger is used to turn it clockwise or counter clockwise (as long as you maintain contact w/ tooth)

Pivoting the fulcrum

• Ring (fulcrum) finger acts as a pivot as the hand turns during instrumentation

• Keeps working end against tooth

Before pivoting

• Clinician is moving working end across facial surface of second premolar

• Only underside of middle finger is visible in photo

After pivoting

• Clinician reaches mseiofacial line angle

• She pivots fulcrum finger to rotate hand slightly

• Working end moves from facial surface to mesial surface of premolar

• Side of middle finger is visible after hand pivot

Orientation of tooth surface

• Misconception — Tooth is vertical

  • Teeth is NOT flat

  • This misconception causes people to position lower shank incorrectly

• True angulation

  • Teeth are tilted

True angulation of teeth (maxillary and mandibular)

Maxillary teeth

• Roots incline inward (Towards middle of mouth)

Mandibular teeth

• Anteriors — tilt inward

• Premolars — nearly vertical

• Molars — tilt slightly outward

Orientation to tooth surface

• Look at surface you’re working on — orient lower shank so it’s in the same direction as the tooth being instrumented on

Lower shank must be parallel to tooth surface

• Tooth has many orientations

• Root surfaces point in different direction

As you move around tooth…

• Orientation must change too

Orientation to proximal surface

A: Incorrect

• Red lines — incorrect alignment to distal and mesial surfaces of maxillary central incisors

B: Correct

• Green lines — Correct alignment to distal and mesial proximal surfaces of maxillary central incisors

Orientation to facial and lingual surfaces

A: Incorrect

• Red lines — incorrect alignment to lingual and facial surfaces of maxillary central incisor

B: Correct

• Green lines — Correct alignment to lingual and facial surfaces of maxillary central incisor

Orientation to proximal surfaces

A: Incorrect

• Red lines — incorrect alignment to distal and mesial surfaces of mandibular molar

B: Correct

• Green lines — Correct alignment to distal and mesial surfaces of mandibular molar

Orientation to facial and lingual surfaces

A: Incorrect

• Red lines — incorrect alignment to lingual and facial surfaces of mandibular molar

B: Correct

• Green lines — Correct alignment to lingual and facial surfaces of mandibular molar

Orientation to proximal surfaces

A: Incorrect

• Red lines — incorrect alignment to distal and mesial surfaces of maxillary molar

B: Correct

• Green lines — Correct alignment to distal and mesial surfaces of maxillary molar

Orientation to facial and lingual surfaces

A: Incorrect

• Red lines — incorrect alignment to lingual and facial surfaces of maxillary molar

B: Correct

• Green lines — Correct alignment to lingual and facial surfaces of maxillary molar