Bond issues

I've recently had an in-office demo of the new CEREC 3 Impressive Windows-based software. I am interested in how REALITY views this technology. When is it cost effective? How is the marginal fit quality compared to a good lab?

Michael Miller, DDS

I've recently had an in-office demo of the new CEREC 3 Impressive Windows-based software. I am interested in how REALITY views this technology. When is it cost effective? How is the marginal fit quality compared to a good lab?

A: CEREC 3 has taken a giant leap forward over previous models. The Windows NT-based, intuitive software definitely improves the learning curve. The mobile camera unit/computer is now separate from the milling unit, which gives the opportunity to simultaneously design additional restorations while another is milled. There is no need for a wired connection between the two components. The 15-inch flat-screen color monitor is cutting edge, displaying the image that is actually an optical impression. This monitor is a great improvement! The camera capturing the image requires no adjustments. You merely stabilize the camera on one tooth distal to the one being prepared and grab the image, just like using an intraoral camera.

Other advances with this model include the milling unit, which has cylindrical and torpedo-shaped diamond burs. The end result is better margins and significantly faster milling times - about 12 minutes. Our comparison between the marginal fit of an MOD inlay made with the CEREC 2 and CEREC 3 showed smaller gaps with the CEREC 3.

There is also an expanded choice of materials, including one millable composite from 3M.

Q: I've heard recently from a respected expert that resin inlays/ onlays have a decreased bond strength at the cement interface. Unlike porcelain, the lab-cured resin is more resistant to bonding cement. Please comment.

A: CoJet from ESPE will give plenty of bond strength between the cement and the restoration. This product takes conventional aluminum oxide and coats the particles with silica. Sandblast the restoration as usual, but then just blow off the excess, leaving the remaining particles embedded in the restoration. Apply silane, which forms a chemical bond with the silica coating and with the resin cement.

Q: I have repaired porcelain several times with reasonably good success. However, one particular case is problematic. The porcelain on a lateral incisor broke, exposing metal. I used the technique described in REALITY; unfortunately, it only lasted overnight. I then microetched the metal and HF etched the porcelain. I then coated the porcelain with silane and proceeded to bond a composite repair. This time it lasted about a week. I suspect the bond to the metal is the weak link. Any suggestions?

A: Our latest information shows that using Alloy Primer from Kuraray will enhance bond strength to metal. Follow these steps: alpha Mask uninvolved areas with LC Block-Out (Ultradent).

Creating some undercuts in the metal with a high-speed bur can improve results.

Q: I have used Demetron curing lights since their inception and have been very pleased with their quality. I am now evaluating the Optilux 501. I have heard that it has the same bulb as the older models. If so, how can it produce greater energy?

A: Our full report on the Optilux 501 is in the 2001 edition of REALITY. The bulb power (80 watts) has been maximized to produce more energy at the end of the Turbo tip. Our tests have not found a significant difference in leakage between the various curing modes, but additional testing is ongoing. The Optilux 501 is our only five-star curing light and gives you all of the polymerization options. However, we still recommend full-power curing.


Dr. Miller is the publisher of REALITY and REALITY Now, the information source for esthetic dentistry. He is an international lecturer and a fellow of the American Academy of Cosmetic Dentistry, as well as a founding member. He maintains a private practice in Houston, Texas. For more information on REALITY and to receive a complimentary issue of his monthly update, REALITY Now, call (800) 544-4999 or visit www.realityesthetics.com. The opinions expressed in the column are not necessarily the opinions of the Dental Economics staff.

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