The Art of Direct Composites

Another study day post; this one is based on a Study Day held by the iCAD Academy.

So already in my first 3 months in practice I've been asked numerous times how much a white filling is.
Despite having some experience with composite at dental school, I still feel a bit guilty telling a patient who wants a white filling in their back tooth, according to my practice policy it will come under private treatment and therefore they will have to pay more.

I really enjoy working with amalgam and I think it's a great material to work with, but I do empathise with patients who are concerned with it's appearance - I used to have a large MOD amalgam in an upper six that was replaced a year ago with a nice white Emax onlay.

I see a lot of really natural and attractive composites online by some really skilled dentists so I have felt some disappointment when looking at my posterior composites; especially where I can clearly see the transition between composite and tooth or a very disappointing attempt at a fissure pattern. My composites were functional, but not pretty.

This study day with Neel and Anup really taught me a lot and I have already put the tips into practice to deliver more aesthetic solutions for my patients.

What makes up composite?

1. Polymer resin matrix, mostly based of bis-GMA

2. Filler e.g. silica, strontium, zirconia silica

Other components include initiators, pigments and stabilisers

So do composites or amalgam (or silver) fillings last longer?

According to studies, amalgams last between 6.6-14 years.

Compare this to 3.3-4.7 years for composite fillings.

BUT a lot of this data is skewed by short studies, testing areas of high failure e.g. cervical cavities, or they do not take into account factors such as operator technique.

So can I restore this cavity with composite?

There are a few factors you need to take into consideration:

1. Occlusal Assessment - check the patient's ICP and RCP, excursions, centric stops. If the composite would be where the centric stop is, or the patient is a bruxist, a composite restoration may not be strong enough to withstand these heavy forces

2. Contact area Assessment - using floss and radiographic assessment. Can you recreate a good contact point?

3. Is there a ring of enamel? This is essential to get a good bond.

4. Is there good moisture control? Contamination with blood or saliva weakens composite and doesn't allow for a good bond to the tooth structure.

Some useful tips:

It may be beneficial to soak the finished cavity with chlorhexidine as this can reduce post-operative sensitivity
Do not use flowable composite to line cavities as it has increased shrinkage and higher concentrations of the monomer which can lead to post-operative sensitivity
Customise your wedge to create a good contact point. Trim with a scalpel or a bur so it is the correct size for the interproximal space
You can also pre-wedge the cavity so that you can visualise the contact point prior to placing the restoration
Use a mico-brush to smooth the composite before curing and be careful not to incorporate dust or hairs!
Shape as much before curing. You want to polish as little as possible as this exposes the flaws in the composite which you will see as white specks.
Bevel incisal fractures buccally to ensure there is no unsupported enamel and to improve the transition between the tooth and the composite or use a Starburst bevel.
DO NOT use bond on instruments or cured over the top of composite to improve appearance as this will lead to staining. Use a specific wetting agent instead - each brand of composite will have their corresponding brand of wetting agent.

Anterior Composites

Here is a step by step technique:

1. Always use a putty matrix made from a diagnostic wax up

2. Place the palatal wall in enamel shade

3. Recreate the contact point either with a customised wedge, a matrix seated in the index (metal or clear), using a clear matrix and wedge or using the Mylar Pull method.

4. Use a small amount of opaque shade composite

5. Use a dentine shade to build up a layer of a few millimetres thick, leaving enough for an enamel layer and small deficiencies to mimic the mammelons in the adjacent tooth

6. Use a SMALL amount of tint to exaggerate these mammelons - usually blue, grey or halo.

7. Finally use a enamel translucent shade to recreate the natural contour of the buccal surface.

The palatal view of the restored upper left central incisor. The labial view is seen in the title photo,

Posterior Composites

Here is a step by step technique:

1. Using a custom or pre-wedging technique, adapt your matrix (circumferential or sectional) to recreate the contact point

2. Turn the class II cavity into a class I i.e. recreate the marginal ridge

3. You can now remove the matrix

4. Use a dentine layer on the cavity floor

5. Using the P K Thomas incremental technique, build up each cusp one by one, creating small triangles to recreate the cusps and cure each separately. This is difficult to explain so please see this video.

6. Add tints to the fissure pattern

7. Add a final layer of enamel shade.

My posterior class II composite. Can you guess if it was a DO or an MO?

Whilst it's great having all these different shades to build up the composite, shade comes with shape!

If you shape the composite properly and finish it smoothly, you can build up perfectly good looking composite restorations in one shade.

One shade composite repair of the upper right central incisor which had an mesial-incisal fracture

For more information please see this article on contouring composites or see the iCAD's website, facebook page or follow them on twitter. Thanks to the iCAD team for holding a great study day!

At the beginning of our study day we were asked which brand of composite we use in practice. It was surprising how many of us didn't actually know! Do you? And more importantly, what type of bonding agent? Please leave your comments below!