Movement
Objectives
You will learn how to properly hold instruments, use fulcrums (finger rests), and stabilize your hand.
You will understand what motion activation means and its various ways of moving the instrument.
You will learn about how to roll the instrument handle and pivot your hand.
You will define adaptation and understand how the instrument's working-end should contact the tooth surface.
You will identify and learn about the three basic directions for instrument strokes.
You will compare the different functions and features of assessment, calculus removal, and root debridement strokes.
Developing Instrumentation
Dental instrumentation is a fine motor skill, meaning it requires small, precise movements of your hands and fingers.
This skill involves your brain, nervous system, and muscles all working perfectly together.
Because these movements are complex, you need lots of repeated practice to learn them well.
Stages of Psychomotor Skill Development:
Observing: First, you watch and learn the skills during your training sessions.
Imitating: Next, you try to copy what you've seen, and your movements might feel awkward or not automatic at first.
Practicing: Then, you repeatedly try these movements until you start to get better and master them.
Adapting: Finally, you fine-tune these skills, making them perfect and natural for you.
Practice Makes Perfect
Muscle Memory: This is what happens when your brain stores the movements you do often.
The more you practice, the smoother your movements become because of something called myelination, which helps nerves transmit signals faster.
Studies show that practicing small, precise movements frequently actually makes your nerves work better by increasing myelin.
It's very important that your practice is good quality; you should always aim to make your movements perfect.
Automaticity: This is when you can perform a skill easily, smoothly, and without having to think hard or feel frustrated.
Key Elements of Practice
To get good at instrumentation, you need a few key things:
Guidance: You need clear, step-by-step instructions to learn the right way to do things.
Practice: You must practice often, especially with someone giving you feedback, to become a master.
Feedback: Receiving simple and quick feedback is very helpful for fixing any mistakes in your technique.
Self-Assessment: You need to be able to look at your own work, spot when you're doing something wrong, and figure out how to improve.
Good practice means more than just doing it correctly once; it means practicing consistently until the movements become automatic and stored in your muscle memory forever.
Movement
Motion Activation: This term describes how you use your muscles to move the part of the instrument that actually touches the tooth (the working-end) across its surface.
When you activate the instrument, your fulcrum finger (which is like an anchor) supports your hand's weight, making your movements steady.
The fulcrum also helps you control where the instrument's working-end goes, and it works like a "brake" to stop the movement precisely when your stroke is finished.
Each instrumentation stroke is very small, moving the working-end just a tiny bit, only a few millimeters, with every motion.
Wrist Rocking
This technique involves moving your entire hand, wrist, and arm together as one unit to create a rotating motion that moves the instrument’s working-end.
Using wrist rocking helps you get less tired compared to just moving your fingers.
Think of it like turning a doorknob; that's the kind of rotating movement you should make.
How it's used:
You should use this motion for all calculus removal when you're using hand instruments.
It helps you keep a relaxed and balanced body position, which reduces stress on your wrist and forearm.
Your fulcrum finger still provides support for your hand while you do this.
Digital Motion
This method means you use only your thumb, index, and middle fingers to move the instrument by bending them.
You use digital motion when you don't need a lot of physical strength to move the instrument.
How it's used:
It's mainly used with ultrasonic instruments, which vibrate to remove deposits.
You might also use it sometimes with tools like periodontal probes (to measure gum pockets) and explorers (to feel for deposits).
It is not recommended for removing tough calculus with hand instruments because it doesn't provide enough power.
However, it's good for reaching tricky spots, like the areas between the roots of multirooted teeth (called furcations).
Rolling
Rolling means gently turning the instrument handle using your thumb and index finger.
This action is vital for keeping the working-end precisely against the tooth surface as you move around it.
Which finger you "drive" (either your index finger or your thumb) will control the exact direction the working-end turns.
How it's used: This technique is very important for making sure the instrument stays in contact with the tooth surface during the entire movement.
Pivot
A pivot is a small, gentle swinging movement of your hand and arm, which relies on your fulcrum finger for steady balance.
This movement helps you move your hand to new positions while keeping the instrument correctly adapted (in contact) with the tooth as it moves around the tooth's curved surfaces.
You typically use pivoting when you move the instrument from one smooth side of the tooth to another, especially around the corners (called line angles) and onto the sides that touch other teeth (proximal surfaces).
How it's used: Pivoting allows you to make small, precise changes that give you better control and help you adapt the instrument to different tooth shapes.
Orientation
It's important to remember that most teeth are not perfectly straight up and down; they are usually tilted in your mouth.
An extremely important part of dental instrumentation is making sure you place the instrument's working-end correctly on the tooth surface you are cleaning.
If you can correctly picture the actual angle of the teeth, it helps you place the instrument's working-end accurately on the tooth roots.
Every single tooth has many different surfaces, and each one of these surfaces has its own unique angle, which is different for the crown (the visible part) and the root (the part under the gum).
Adaptation
Imagine the instrument's working-end is divided into three parts:
Leading-third: This is the part closest to the very tip or toe.
Middle-third: This is the section in the middle.
Heel-third: This is the part furthest from the tip or toe.
Proper adaptation means that the first 1 to 2 millimeters of the side of the working-end should always be touching the tooth.
Ideally, the very tip or toe (the leading-third) of the working-end should constantly stay in contact with the tooth surface.
Sometimes, both the leading-third and the middle-third can touch the tooth, but the heel-third should never touch the tooth surface.
Choosing the Correct Working-End
When you use an instrument that has a working-end on both sides (double-ended) to clean a back tooth, you need to pick the right end for the best cleaning.
To figure this out, you should look at how the lower part of the instrument (the lower shank) lines up with the back surface of the tooth (the distal surface).
You can also use a visual trick called "the mountains" to help you:
"Up and over" (for one side)
"Down and around" (for the other side)
Instrumentation Strokes
When you move the instrument's working-end across the tooth surface, you must be very careful about where the gum tissue (junctional epithelium) meets the tooth to avoid hurting it with the sharp edges.
An Instrumentation Stroke: This is simply the action of moving the instrument's working-end against the tooth surface.
There are different kinds of strokes you'll use, such as:
Strokes for removing calculus (hard, hardened plaque).
Exploratory strokes for finding calculus.
Stroke Direction
All instrumentation strokes should move in a direction towards the biting surface of the tooth, moving upwards and away from the delicate gum tissue at the bottom of the gum pocket.
The direction you use your stroke depends on which specific part of the tooth surface you are working on.
There are different types of stroke directions you will learn:
Vertical strokes (up and down)
Oblique strokes (diagonal)
Horizontal strokes (side to side)
Multidirectional strokes (combining different directions)
Types of Strokes
Assessment Strokes
These strokes are used to check the tooth surfaces and find any calculus deposits (hardened plaque).
Exploratory Stroke: This is a type of assessment stroke also used to re-check the tooth surface after you've already removed calculus.
When performing an exploratory stroke, your fingers should be relaxed, making a smooth, very light stroke that is medium in length, gently touching the tooth without pushing down.
Calculus Removal Strokes
These strokes are performed to break off and remove calculus deposits from the tooth surface.
You mainly use instruments called curets and sickle scalers for these strokes.
How to apply them:
You need to use a moderate "pinch" pressure on the instrument handle with your fingers, along with firm pressure against your fulcrum finger (your anchor).
This means you apply side-to-side pressure as the instrument's cutting edge gently goes into the tooth surface to grab the calculus.
You should use short, firm, and controlled strokes to effectively remove the calculus deposits.
Root Debridement Strokes
These strokes are designed to remove any leftover deposits and bacteria from the root surfaces, especially in deep gum pockets.
They are like lighter, "shaving" strokes performed with moderate pressure.
Stroke Length: These strokes are a bit longer than the short strokes you use for removing calculus.
You apply light pressure against the cementum (the outer layer of the tooth root) during this process to avoid damaging the tooth structure.