Composite Dental Filling Procedure: Steps of a Class 2 Resin

After 15 years as a dentist, I have perfected the composite dental filling procedure. This guide and the accompanying video will show you all the steps I take, why each step is essential, and what an average size cavity and filling look like. Specifically, this is for a class two filling, which means a cavity formed between the teeth. 

Most people don’t know that fillings are very technique-sensitive. If not done correctly, fillings can cause pain, throw off your bite, trap food, be unsightly, or generally just feel off. That is why each step in this procedure is so important.

What Are the Steps of a White Composite Dental Filling Procedure?

1. Numb the tooth.
2. Drill an optimal slot for a white composite filling.
3. Remove remaining decay.
4. Ensure no decay remains.
5. Place matrix band.
6. Place wedge.
7. Place glass ionomer liner.
8. Etch the surface of the enamel.
9. Bond with a universal bond.
10. Set composite filling in layers.
11. Check the bite.
12. Check the contacts.
13. Remove excess composite.
14. Repeat steps 10 to 12 until the filling feels natural.
15. Polish filling.

Dental Composite Filling Diagram Slot Prep Class II 2 Finished

How to Optimally Drill a Slot for a Class Two Composite Filling

When you drill a slot for a class two composite filling, you want to expose the decay and make it to the ideal specifications. To do this, I use a high-speed drill with plenty of water. There is debate about the perfect specifications; however, the smaller the slot is, the better. In fact, I make the slot only as big as I need to insert all my instruments, check that I have adequately removed all the decay, and can seamlessly fill it with a white composite filling.

Making the filling as small as possible and using plenty of water will help prevent tooth sensitivity. Watch this video for more about preventing tooth sensitivity after a filling.
Decay in Real Life Compared to What it looks like on the X-ray
What decay looks like on an x-ray compared to what it looks like when exposed in real life. The arrows point to the exact same cavity in the mouth and on the x-ray.

How to Remove Decay for a Filling

Once the slot has been optimally drilled, I have great visualization of the decay unless I removed most of the decay while drilling the slot. With the decay exposed, I then use a slow-speed drill to remove the decay. A round drill bit will remove the decay without removing much of the healthy and solid tooth. This is one way to tell if you have removed all the decay because removing the decayed tooth will come out with a mushy consistency. If I drill on a partially decayed tooth, I will see a flakey texture. Or, if it is a healthy tooth structure, it will look dusty as you drill, indicating you no longer need to remove decay.
Drilled Decay Has A Mush Consistency
When drilling on tooth decay, the debris is a mushy consistency.
Partially Decayed Tooth Flaky Consistency Appearance when Drilled
When drilling on the partially decayed tooth, the debris is flaky.
Drilled healthy solid tooth with a powdery dusty consistency
When drilling on a healthy solid tooth structure, the debris is powdery.

How Do I Ensure I Removed All The Decay?

Removing all the tooth decay is essential to a composite dental filling procedure, so I have two more checkpoints to ensure I have removed the whole cavity in addition to its consistency explained above. First, I look to see if the tooth left behind is white to yellow in appearance. I may need to drill more if the tooth is orange, brown, or black. Lastly, I use my pointy explorer to feel the tooth. If it is sticky, I need to remove more decay. If it feels and sounds as hard as a rock, then I am done. Therefore, I ensure the decay is gone by testing how the tooth looks and feels and its consistency when removing the decay.
Partially Decayed Tooth Appearance Orange and Brown Color
The orange and brown appearance of partially decayed tooth. 
Healthy Color and Appearance of Dentin and Tooth Decay Free
The yellow appearance of the healthy dentin layer of the tooth.

What Does The Matrix Band Do?

There are many types of matrix bands. I use a traditional matrix band that fits tightly around the circumference of the tooth. The matrix band helps isolate the filling from blood or saliva. It prevents liquid and doughy filling materials from flowing out of the tooth slot. Lastly, the matrix band helps shape the filling.
Matrix band placement for class 2 composite dental filling

What Does the Wedge Do For A Filling?

The problem with the matrix band in the previous step is its thickness. Once the filling is set in the tooth and we remove the matrix band, it will leave a gap between the teeth. This small gap can catch food and cause pain and other problems. To compensate for the thickness of the band, we place a wedge between the teeth. The wedge separates the adjacent teeth providing more space for the filling, so when I remove the matrix band and wedge, the teeth return and contact each other despite the thickness of the matrix.

 The wedge also adapts the matrix band tightly against the tooth, which provides a smooth transition between the tooth and the filling.
Wedges Placed for Class two composite filling white resin

What Does A Glass Ionomer Liner Do?

A glass ionomer liner is a layer of filling material that sits over the part of the filling closest to the dental pulp. The primary function of the glass ionomer liner is that it reduces sensitivity after a filling. A second function of the Glass Ionomer is that it releases fluoride to strengthen the tooth from any possible decay. Lastly, it provides an initial layer since you should place fillings in layers. We will cover this in a moment. Placing glass ionomer under every filling is a crucial difference that sets us apart from other dental practices, so our patients rarely experience sensitivity after a filling.

Watch this video if you want all the ways a filling could cause sensitivity.
Liner in SLot Prep of Class two dental filling

Is The Research Correct and Complete On Glass Ionomer Liners?

There is research that shows GI liners don’t reduce sensitivity. However, in my practice, I went from having a couple of patients a year with sensitivity to almost never having patients with sensitivity. The difference was that I started using a glass ionomer liner on every filling. Initially, the research convinced me I didn’t need to use a liner, but the results have been very apparent to me. Glass ionomer liners reduce sensitivity after a filling. I believe we need more research on why there is a discrepancy in Glass Ionomer anti-sensitivity results.
Fuji GC Glass Ionomer Liner Before Mixing

What Does Etch Do For A Dental Filling Procedure?

Next, we place 35% phosphoric acid etchant on the tooth and liner for a few seconds and then thoroughly rinse it away. Then we lightly dry off the tooth. Etching the slot will enhance the bond strength of the filling we will put in.
Applying Etch Etchant 35 Phosphoric Acid Total

What Does Bonding The Composite Filling Do?

After etching, we scrub a resin bond onto the tooth. I use the Peak Universal bond because it is the strongest bond that I have tested. The bond attaches the filling to the tooth and is the weakest point of the filling, which is why it is vital to use the strongest bond. I also make sure to “scrub” the bond in because that is the second most important factor for a strong bond.
Universal Peak Bond Brush For White Fillings Resin Composite Bonding

Why Do We Place The Filling in Layers?

Composite dental fillings will shrink 1% to 5% when a UV light hardens the doughy resin composite. Adding the composite in layers will prevent resin shrinkage from separating from the tooth and prevent stress on the tooth that can cause a biting sensitivity. Watch this video about filling sensitivity for more on that.

Filling with resin in layers also allows the UV to adequately set all the filling material. If a filling is deep and the filling is not set in layers there could be unset filling at the bottom of the filling. 

I use a transparent blue condenser to pack my fillings. This condenser helps place the filling in layers and reduce stress. It also helps press the filling against the matrix for a tight contact. When the filling is set in place with the condenser, it prevents the shrinkage from happening inward to place more stress on the tooth. The condenser also helps shape the filling nicely between the teeth. Lastly it encourages light to travel  to the bottom of the filling so it is firmly set. 

After I take the condenser out, I can add another layer to fill the void the condenser left behind and then finish the composite dental filling procedure.
Blue Transparent Condenser for Resin Fillings and Curing

Why Do We Check The Bite After The Filling?

If a filling is over-filled, it can completely throw off the bite. If the bite cannot settle correctly into place for long enough, it can cause permanent damage and pain in the jaw. However, the problems don’t end there. If the filling is too high, it can take the brunt of the biting force, putting too much pressure on the ligaments holding the tooth in place. The bruised ligaments can be painful and make it difficult to eat.

To avoid overfilling a tooth, we use a combination of checkpoints. First, we have a patient bite on blue carbon paper. If it leaves a mark on the filling without any spots on the natural teeth, most likely the filling is too high. However, that test sometimes gives false negatives, meaning no blue dots appear on the filling even though the bite is too high. Asking the patient if the bite feels off is another test. That is not a 100 percent accurate test because it is hard to judge a bite when numb. Lastly, we test the bite by the sound an even bite makes. Dentists can hear a chomping sound when a patient bites down on all their teeth evenly. We use a combination of these three tests to check for an even filling.

If there is a high spot on the filling, we simply use a finishing bur in the high-speed drill to remove the high spots. Then we repeat this step until the filling is even with the rest of the bite. During this step of the composite dental filling procedure, we also smooth off sharp edges that irritate the patient.
High Spot on Filling Checking the Bite Blue Paper

How Do We Test The Contact Of the Composite Filling?

Once the white filling is level, we floss between the teeth. We want to see if the floss snaps between the teeth and if the floss shreds. If the floss glides through without a snap, the contact point is open, and the filling needs to be redone. An open-filling contact can cause food to trap between the teeth causing pain, gum disease, and tooth decay. If the floss shreds when flossing, you must smooth off the filling until it doesn’t catch the floss.
Smooth Between Dental Fillings

Why Do We Polish The Filling?

The last step of the filling is to polish it off. Polishing is the least important of the steps, as the filling will polish over time the more it grinds against the other teeth. However, polishing off the tooth is essential for the patient's satisfaction, so we always take this step.
Final Result of Composite Dental Filling Procedure White Resin
Final result of the composite dental filling procedure used throughout this article.

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