Let’s now explain some more on the second pillar of the Bioclear method, and that is preparation design.

I have to say, this is my favorite thing to talk about because I believe that by addressing prep design we have the ability to really make a difference for our patients.

What I mean is this: tooth fractures still occur at a high rate even with our change to adhesive composite bonding over the past decades. In fact, tooth fractures are the third leading cause of tooth loss worldwide.

The key to improving our chances for success is in proper engineering of the preparation. We prep teeth differently for gold vs pfm vs porcelain vs zirconia because the engineering demands it. We need to do the same for composite. 

This is built upon the concept of compression, and it is the foundation of the Bioclear preparation. Dr. David Clark studied engineering concepts and talked to structural engineers about our traditional tooth preparations. He was astonished at what he learned Engineering experts concluded that our traditional preps were more harmful than good for our patients’ teeth.

What I mean is that when the composite in a tooth preparation is in compression, it is four to five times stronger than a composite in tension. Unfortunately, all standard preparations done by most dentists today are little different than those for amalgam, and that leads to more tension in a tooth than compression. With Bioclear preparations designed by Dr. Clark, patients’ restorations should last far longer than ever before. In fact, studies at the University of Minnesota show that the Clark preparation design lasted about eight times longer in cyclic load studies than the standard G.V. Black type of preparation.

Let’s talk about your Class II preparation. Most of us have been taught to cut a box and extend that box across some or all of the occlusal groove. For an MOD composite, this creates a long cut that invites tensile forces that work against the cusps and can lead to fracture.

The Clark Class II preparation, in contrast, is built upon the concept that placing composite merely “into” a preparation does not protect the cusps. But when composite goes over a tooth and around a tooth, you not only protect the tooth in a far greater manner, but you create a more polishable, more hygienic restoration that happens to look good and stay good looking as well!

Here are the key components we need to make this happen:

1. A radius wall on the occlusal surface. This is a long, curvaceous arc that begins at the cavosurface extending out towards the cusp tips. Depending on how wide the preparation is, it may even extend all the way to the cusp tip. This gives us the ability to create compression on the occlusal surface. Even cracks under cusps can be protected using this concept.
2. A high enamel-to-dentin adhesion area. Our goal should always be to minimize dentin cutting, taking away only the diseased area selectively and maximizing the amount of enamel surface to bond to. Ideally over 70% of the surface are is enamel and 30% or less is dentin.  Bioclear restorations are enamel driven. This is where the classical G.V. Black prep design really fails to achieve this ratio resulting in greater chances of microleakage, overhangs and non-polished plaque attracting areas leading to unhealthy tissues.
3. An infinity edge versus a “margin”. We do not create margins nor do we look to finish back to the margins as you probably do now. Instead, we create a flow of material that will reach well beyond the line angles bonded to acid-etched, biofilm-free enamel that will be smooth, undetectable, and remain highly polished. As a bonus, it is much easier for the dentist to achieve this than with a G.V. Black prep.

You will learn exactly how to do all of this in our courses.

When it comes to anterior prep designs, our goal is pretty much the same: we are still creating compression joints at the areas of function, but in addition, we want to create blending of composite to tooth that will be perfectly indistinguishable to the viewing eye.

Again, we can do this utilizing the concepts of whole tooth bonding, infinity edges, and radius walls.

The Bioclear Method with preparation designs by Dr. David Clark is something we are most proud of and eager to teach you, so you can be as proud of them yourself. You’ll see the amazing difference it will make for your restorations—and for your confidence—when you’ve provided the finest treatment for your patients, based on real engineering principles.