Oral Health Group
Feature

Cerec and Paradigm

March 1, 2011
by Lee Ann Brady, DMD


In the last six months I have only used a matrix band one time, and I am enjoying class two and class three restorations more then ever, thanks to my CEREC machine and Paradigm composite blocks. I like to joke and tell people that CEREC and I are the same age in dentistry, because the technology was brought to the US market the year I began practice. I was not one of the first people to jump in and use the technology back in 1988, as a matter of fact I didn’t pay much attention thinking, “that will never take off.” I realize looking back that part of my resistance stemmed from my fear of technology. I am not naturally inclined to use technology and most of the time feel like everyone else is more proficient with his or her computers, cameras and iPods than I am.

I finally took a serious look at the technology when CEREC 3D came out and my Patterson rep arranged an in office demo. I was impressed by the technology, but truthfully couldn’t see how the numbers worked. At the time I was not doing partial coverage bonded porcelain, was comfortable with PFM for my full coverage, and that was the scope of the technology. Several years later after moving out of full time practice into education, I was given the opportunity not only to play with CEREC, but to spend time with some of the expert trainers and use the technology with their support. This was two years ago, and I have been an avid fan, and my day-to-day use of the technology has continued to grow since that time. It wasclear that for me that the integral part was training and getting comfortable enough with the technology that I could use it on patients without worrying about messing up the schedule or looking like I wasn’t sure what I was doing, so I strongly encourage everyone to commit to their learning process.

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One of my favorite applications for the technology has been using Paradigm composite blocks to restore class two and class three restorations. Truthfully I have also been known to use my machine and mill some class one restorations, but when the size of the restoration is smaller then the sprue even I give in and place the composite directly. The advantages of utilizing milled composite in these clinical situations are easy to share. I can reliably create contacts in all of the clinical situations I am presented with during the design phase, customize the intensity of the contact as well as it’s dimension in both a bucco-lingual and occluso-ginigval perspective. The days of struggling with matrix bands and wedging devices are over for me. I never wondered why there are so many booths at conventions on new matrix systems, it’s because being able to place a matrix system, wedge the teeth apart and predictably know you have a contact isn’t a part of everyday dentistry. Instead we remove the matrix, finish the composite, and then sheepishly reach for the floss, place it in the contact, turn our head and hold our breath as we hope to hear that longed for “snap”. What’s even worse are the phone calls days or weeks after the appointment where the patient reports packing “chicken” between their new filling and the adjacent tooth!

This is a thing of the past in my practice thanks to milling these restorations. I also have the ease of placement and finishing. I no longer have to layer in the composite and light cure each layer, wondering about the density of how I am condensing it against the previous layer. The Paradigm blocks eliminate worrying about voids from lack of adequate condensation or ineffective polymerization. I also have all my occlusal anatomy in the restoration before I seat is, cutting down dramatically on finishing time. In my hands I can image, design, mill and place a milled composite in the same or less time then doing one the conventional way, and I have a superior restoration.

I prepare the tooth as if it were going to receive a direct composite, I do not worry about draw of the restoration, accept in the interproximal box, where to minimize the marginal gap I want the walls parallel or to draw. Any undercuts in the body of the restoration are handled during the seat; as I place these restorations with composite, not resin cement. Once the prep has been completed, I powder the prep, image and then I’m ready to design. For smaller restorations, utilizing the Biogeneric design feature of the new 3.8 software it is not necessary to get a virtual impression of the opposing arch or a bite record. As the restoration size increase I will sometimes get these additional images to reduce adjustment time of the occlusion. My most complex paradigm composite restorations mill in 5-6 minutes and then we are ready to place them in the mouth. I place the sprue on the interproximal contact, and then adjust to exact tightness; some folks place the sprue on the undersurface of the restoration.

Once my contact is set, I air abrade the underside with fifty-micron aluminum oxide, and apply a coupling agent like the resin from your dentin adhesive or Monobond Plus. Preparing the tooth in my hands looks like applying phosphoric acid to all the enamel margins, waiting 10 seconds, then covering the dentin for an additional 15 seconds. Once I have rinsed and dried I apply Gluma as a desensitizer. I agitate the Gluma against the dentin for ten seconds. It is important to remove the excess Gluma, so with a cotton pellet I blot the cavity prep and then dry against the patient’s bib until the cotton comes out of the prep without leaving a circle on the paper. Following Gluma I apply I-Bond total etch dentin adhesive. The primer and resin are in one bottle, I apply to the dentin for 15 seconds, then air dry for 10 seconds until the prep looks satiny. Leaving the dentin adhesive uncured, I place a VenusFlow, a highly filled flowable, into the preparation liberally, making sure to coat all of the walls and the floor of the prep and place the restoration until fully seated. Holding the restoration in place Ilean all of the excess resin, including flossing. Lastly I place an oxygen barrier and then fully cure from all sides and angles.

If there are significant undercuts in the body of the prep, I will use my regular Venus composite instead of the VenusFlow. I heat the composite until it will flow easily, and using the same procedure as above place the restoration. When using heated composite I have found it is important to turn off any high volume suction that draws air over the tooth until after the restoration is in place. If the composite cools too rapidly, it hardens and you will not be able to get the paradigm down completely.

My goal when I clean resin, is to get it all off and not have any cleaning to do with high-speed instruments or hand instruments. I never get it quite this good, but can get close. I like to use a rubber tip stimulator, which my assistant wipes with an alcohol two by two, or the micro tip rushes to clean the uncured resin. Once fully cured I utilize a brownie point in a high speed hand piece, running at low speed to clean al the excess and margins. The brownie will cut the resin, but not the enamel, and you do need to be using an electric handpiece that you can dial down for this, or they turn into little grenades. I finish the paradigm with the same polishing system I use for direct composite, and then last step is diamond-polishing paste on a prophy cup.

My experience is that the paradigm is beautiful, its translucency allows the restorations to truly be a chameleon and disappear once cemented. If I need to bring the value up I choose a more reflective flowable composite like Venus Flow. I match the shade of the flowable I am cementing with to the tooth, and rarely if I have a very dark underlying prep from secondary dentin or amalgam stain, I apply a thin layer of opaque direct composite as a block out prior to powdering and imaging.

The addition of milled composite has made my life easier, dentistry more enjoyable and the results better clinically and more predictable for my patients. What more could I ask? OH

Dr. Lee Ann Brady earned her DMD f
rom the University of Florida College of Dentistry. She practiced in several private restorative practice models for seventeen years before leaving to devote her time to teaching. While in private practice Dr. Brady taught part-time at the Santa Fe Community College dental Hygiene program. In January of 2005, she joined the Pankey Institute as a full time faculty member, and became Clinical Director in 2006. Dr. Brady joined Spear Education as Exec VP of clinical education in Sept. of 2008. In addition to her teaching responsibilities she maintains a limited clinical practice focused on comprehensive restorative.

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