Yet again I have to say thank you to Dr. Brian LeSage. I have been having a blast incorporating a technique I learned at his lecture a month ago into my anterior composite preparations. The idea behind the “starburst” bevel is to create an interface between the composite and the natural tooth that is completely invisible to the eye. If we step back for a moment and think about why a restoration margin is obvious the bevel technique will make perfect sense. The two main reasons that we can see the delineation between the restorative material and the tooth is first a difference in shade. If the restorative material is different in value, chroma or hue our eye will be able to discern where it begins and ends. The second reason is that the light absorptive and reflective characteristics of the resin are different from enamel over dentin. Given this second factor, even if we perfectly match the shade, we can often still see the margins.
The esthetic use of a bevel when placing composite restorations is to create a gradual transition between all tooth structure and all resin. Between the two, we have decreasing amounts of tooth overlaid by increasing amounts of resin. The bevel creates a transition zone where the light characteristics of the two materials are blended in an attempt to “fool” our visual perception. These same concepts are why butt joint porcelain margins are less esthetic than when we drop a shoulder or a labial veneer on our onlay preps. When I saw the “starBurst” Bevel for the first time I knew it made brilliant sense because of the randomness of the depth and width of the bevel. The pattern of varying the two layers of resin and tooth creates so much visual blending from our brain that the margin simply vanishes. I wanted to write this post as soon as I learned the technique, but decided to try it out first so I could share my experience with the technique.
I have been incorporating the new bevel technique ever since and it is incredible. I use a fine football shaped diamond in my high-speed, but at 75% power without water. Once the prep shape is complete and the decay has been removed I create the bevel. It is critical to continuously vary the depth of the bevel as well as the width. I move my hand slowly from the bevel outward, than back in towards the margin altering the pressure. This latest case was a great test, as the shade was very challenging. The tooth is an A1 in chroma and Hue, but very low in value giving it a grey appearance. I completed the basic prep and then placed the bevel as you see in the first photo. I used .5mm of Venus Diamond Clear to create the facial and mesial walls of the restoration and cover the bevel. I then filled the remainder of the prep with Venus Diamond A1. The last step was finishing and polishing.