I had a patient come in today with a onlay out on the upper left first bicuspid. Fortunately the onlay and the tooth were in perfect shape and we would be able to bond it back in place. The challenge of doing this was returning both the tooth and the inside of the porcelain onlay to fresh surfaces that would accept a bond. In this case all the resin cement was on the intaglio surface of the onlay, and getting the tooth ready would not be the issue. The idea of picking up a handpiece to clean the inside of an all porcelain onlay however, is gut wrenching. Using a hand instrument to clean it out is an exercise in frustration.
I only have one tool in my office that melts away resin materials and doesn’t cut or damage enamel or porcelain, the brownie. The brownie point is one of the most underused and under appreciated instruments if you ask me. On the other hand my assistant knows to have not just one but several out for every procedure that we do. I use friction grip brownie points in y high-speed handpiece. You never want to run a brownie at high-speed as they will turn into little grenades. So if you have an electric system dial it down to half speed, and if you use electric be very delicate on the rheostat. You can change the shape of the brownie to anything you need by running it against a diamond bur held in your other hand.
So with my loupes on and a high-speed brownie, the internal surface of the onlay was clean and ready in just a moment or two. I reshaped the brownie into a fine point part way through to gain access to the fine details on the inside of the onlay. The only thing that was left to do was bond it back in. I used 5% hydrofluoric acid to etch the porcelain. After rinsing and drying I used Monobond Plus by Ivolcar to condition the porcelain and then bonded the onlay in with Multilink.