How to Prevent and Manage Bonded Contacts
With the increased use of bonded all-ceramic materials in dentistry today, particularly in the posterior, one frustration I hear repeatedly from my fellow colleagues is bonded contacts. Unfortunately this happens and is most difficult to deal with in the posterior because of access, broader contacts and the use dual-cure cements.
Anyone who has ever had this happen to them knows just how frustrating and time consuming it can be. The following are a few tips and tricks I’ve learned over the years to help avoid the frustration.
The first and most simple thing to do is to allow for floss through the contacts during the gel phase of the cement, when it will simply peel away from the margin. Its all about timing: If you floss too early, you risk making a bigger mess by smearing more cement around or worse, making the tissue bleed and compromising your bond at the margin. If you floss too late you have tons of interproximal cement and bonded contacts to contend with.
To figure out the time your particular dual-cure cement hits it’s gel phase, have your assistant start a timer as soon you start mixing the cement. Once the restoration is in place, periodically tap the cement with an instrument and when you feel the cement starting to gel, make note of the time as a reference for the future. Keep in mind there will still be a little variance in times due to variable conditions in your office, such as temperature and ambient light. In addition, some cements have a very short gel phase while others have an extended gel phase.
Another useful tip is to place a material on the adjacent contacts to inhibit bonding. One material that works well for this is Blue Sep from Parkell, which is a blue liquid you can paint on the adjacent contacts; just be sure not to get any on the tooth structure you are bonding to.
If you are unlucky enough to still have a bonded contact, try using an interproximal saw such as QwickStrip from Axis. The important thing to remember when selecting an instrument to use is that it should be noncutting on the sides otherwise you will end up with an open contact. After getting through the contact I find a 12 blade works really well for removing the remaining cement.
John R. Carson, DDS, PC, Spear Visiting Faculty. [ www.johnrcarsondds.com ]