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ACE Panel report focuses on steps dentists take when bonding crowns, bridges with resin cement

November 05, 2020

By Mary Beth Versaci

ACE Panel report graphic
Bonding: The latest ACE Panel report includes responses from 326 ACE Panel member dentists on questions related to the steps they take when bonding crowns and bridges with resin cement. 

Although many dentists follow best practices when bonding crowns and bridges, they could improve the process by communicating with their laboratory to confirm the steps performed there, making sure they use an effective cleaning technique after try-in and verifying they use the correct primer with their chosen restorative material, according to an ADA Clinical Evaluators Panel report published in the October issue of The Journal of the American Dental Association.

The report includes responses from 326 ACE Panel member dentists on questions related to the steps they take when bonding crowns and bridges with resin cement.

Photo of Sharukh S. Khajotia, B.D.S., Ph.D.
Dr. Khajotia
"When we developed the first draft of the survey, our focus was on the cements used for the retention of crowns and bridges — what were the types of resin cements available, why were dentists choosing those cements, and what were the compositions of the crown and bridge materials being bonded?" said Sharukh S. Khajotia, B.D.S., Ph.D., one of the report's co-authors and a member of the ADA Council on Scientific Affairs’ ACE Panel Oversight Subcommittee. "It then became apparent that dentists had questions about the various steps involved, particularly when cementing zirconia restorations versus lithium disilicate restorations, so the survey instrument was modified to include questions about the try-in, priming and bonding steps, as well as the cleaning steps performed by dental laboratories and dentists."

Of the respondents, 86% said they use resin cements for bonding crowns and bridges, and resin cements used with a primer in the etch-and-rinse mode were the most popular.

When placing a lithium disilicate restoration, 45% of responding dentists said they etch it with hydrofluoric acid in their office and 42% said they ask the laboratory to do it for them. Regarding primer, 67% use a silane primer before bonding, while 23% use a universal bonding agent that includes silane.

"A higher number of respondents than expected indicated that they etch lithium disilicate restorations in their offices. This is surprising because lithium disilicate restorations are often etched by dental laboratories when fabricating crowns and bridges," said Dr. Khajotia, adding he was also surprised by the number of dentists who rely on silane in their universal bonding agent, as the use of a separate primer containing silane has been shown to produce more durable bonding.

For zirconia restorations, 70% of the participants said their restorations are sandblasted in the laboratory. Similar percentages of dentists reported using a primer containing 10-methacryloyloxydecyl dihydrogen phosphate and a universal bonding agent containing 10-methacryloyloxydecyl dihydrogen phosphate, with 39% using the primer and 34% using the universal bonding agent. Both are effective in bonding to zirconia.

Half of the respondents said they clean their lithium disilicate or zirconia restorations with a cleaning solution. However, there were some dentists who reported they clean saliva off zirconia crowns with phosphoric acid after try-in, Dr. Khajotia said.

"This is surprising because it has been shown that phosphoric acid does not remove the organic layer deposited by saliva on zirconia surfaces," he said.

The techniques used to cure resin cement varied among respondents, with 46% using a light cure; 31% saying it depends on the material and restoration thickness; 15% using a chemical cure; and 9% using both a chemical and light cure.

Responses also varied for the methods the participating dentists use to clean excess resin cement, with 85% cleaning partially cured cement after tack curing; 28% cleaning fully cured cement after the final cure; and 21% cleaning unset cement immediately after seating. Respondents could pick more than one option.

Dentists can view the entire ACE Panel report online and download the PDF at JADA.ADA.org.

ACE Panel reports feature data from ADA member dentists who have signed up to participate in short surveys related to dental products, practices and other clinical topics. The ACE Panel Oversight Subcommittee of the ADA Council on Scientific Affairs writes the reports with ADA Science & Research Institute staff.

The reports aim to offer ADA members a way to understand their peers' opinions on various dental products and practices, offering insight and awareness on new products and techniques that can benefit patients and the profession.

Members are invited to join the ACE Panel and contribute to upcoming surveys, which occur no more than once every few months and usually take five to 10 minutes to complete.

To learn more or join the ACE Panel, visit ADA.org/ACE.