Composite resin repairs

Michael Miller, DDS

Q: What is the most current recommendation for composite resin repairs or re-surfacing? Lately, I have been following the Reality recommendation to use CoJet, but I am unclear regarding the step-by-step sequence. Do you etch the enamel first or use the CoJet on the remaining composite first, then etch and prime the tooth structure? Do you then apply silane to the composite or not? I understand allowing silane to contact the tooth can decrease the bond. I have also heard rinsing after use of CoJet will weaken its effect.

A: CoJet was never really designed for repairs. That`s why the repair technique, which is detailed in the 2000 edition of Reality, does not include using it. As you mentioned, CoJet loses some of its efficacy when it is rinsed off. It`s rinsed off because you need to etch the adjacent tooth structure after sandblasting. Therefore, we continue to recommend the repair technique described in our book.

Q: Currently, I am using Nexus by Kerr with OptiBond Solo Plus. I am thinking of switching to Calibra by Dentsply/Caulk. Do you have any recommendations regarding the switch and the compatibility of Calibra and OptiBond.

A: The light-cured base component of Calibra will work perfectly fine with OptiBond Solo Plus, but we advise against using OptiBond Solo Plus with any dual-cure or self-cure cement. Therefore, if you are using Calibra to cement an inlay, onlay, or crown, you would want to use it in the dual-cure mode with a dual-cure adhesive such as Prime & Bond NT Dual Cure.

Q: What technique do you recommend for provisionalization when doing an onlay, such as a DOL in the last tooth in the arch. I have had trouble with the direct light-cured provisionals coming out when there is no adjacent contact to help hold them in. Also, when I have fabricated resin or composite provisionals and cemented them in, they tend to dislodge. However, I`ve had success spot-bonding to the occlusal of the prep with a hard acrylic temp material and have recently used Fermit-N with spot bonding.

A: Spot bonding within the margins of the preparation should certainly work, but requires etching a section of the preparation without actually sealing it with anything other than the aforementioned Fermit.

Here`s another approach: Fabricate a composite provisional using one of the dual-cure provisional materials such as Isotemp or Luxatemp Solar inside a preoperative impression. This is a very fast technique that gives a provisional in less than five minutes. Sandblast a small area of the external surface of the provisional onlay adjacent to a margin that is clearly out of occlusal contact. This is usually buccal of a maxillary tooth and lingual on a mandibular tooth, although it could be on the opposite surfaces - just as long as it is out of occlusion.

Cement the provisional with Durelon. After cleaning off the excess, etch the enamel and the adjacent sandblasted area of the composite provisional. Rnse, dry, and apply a flowable composite from the sandblasted area onto the etched enamel. This will effectively bond the provisional onto the tooth, without having to etch the actual preparation.

When it comes time to remove the provisional, use a disc such as a Sof-Lex XT (coarse) to sand off the flowable composite on the enamel, and then pop off the provisional.

Q: Since Calibra try-in pastes do not match their cement analogs, do you have any recommendations to predict the shade veneers will have after cementation with Calibra?

A: Most cements will only affect the shade if the veneer is less than 1mm thick. Even then, the thin layers of cement usually have minimal influence on the final shade of the veneer, except for white opaque, which can brighten a veneer even in a thin film.

However, the try-in pastes are not very accurate; we recommend placing a small amount of the cement on the unetched tooth preparation, then light cure it. Wipe off the air-inhibited layer and coat the cement with a very thin layer of KY Jelly. Then, place the veneer, also lightly coated with KY Jelly, over the cement. This is not a perfect solution, but it will get you close to what you could expect after cementation.

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.

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