Article Surfing Archive

Having been practicing dentistry in San Diego for 22 years, every now and then I would get a phone call from an emergency patient who broke a tooth. In most cases, the usual way is to take an impression of the tooth, send it to a dental lab, fabricate a plastic temporary crown and see the patient in two weeks when the permanent crown comes back from the lab. Well, the state-of-the-art CEREC machine changes all that.

Now, the patient with a broken tooth can have a new, custom-made porcelain crown cemented the same day! After the broken tooth is diagnosed to have a crown made, the tooth is 'prepared' the usual conventional manner. Then with an infra-red camera, I take a few 3-dimensional pictures of the tooth. These digital impressions are captured and then digitized utilizing some sophisticated algorithm. The CEREC Biogenic software will further calculate the exact dimension of the tooth, and based on my instructions, give me a proposal of what the restored tooth should look like. With the on-screen editing tools, I can accentuate the anatomy of the crown, adjust the contour or smooth off the surface. This is done by right click the control pad and at the same time, 'moving' the track ball on the computer keyboard. After these minor adjustments are performed, the proposal will be sent digitally via a wireless router to a 'milling chamber' where the crown is milled out from a block of porcelain. This milling process is carried out by using two diamond drill bits, one will grind out the contour of the outside surface of the crown, and the other drill bit will do the inside. The porcelain block will 'move around' according to the programmed milling sequences while the two drill bits are rotating at very high RPM. In my office, I have a large inventory of blocks so that it is never a problem to match the crown to the exact shade and translucency. In a short 10-15 minutes, the crown is milled and is ready to be tried in. A lot of the times, custom stain is added and the crown is glazed for 6 minutes in an 800'F oven.

There are a lot of advantages of the use of this CEREC machine. For the patient, they will get the crown the same day, no longer have to wait for two weeks or the second appointment. No second appointment also means no numbing up the tooth the second time. These days, seems like everyone has a very busy schedule, who want to come back to the dentist for a second appointment, unless it is necessary? For the tooth, it gets the crown immediately. When the tooth is 'sealed' the same day it is prepared, there is a lesser chance for any inflammation (toothache) to develop inside the pulp (the nerve tissue) of the tooth. For the clinician like myself, it is an opportunity to unleash my 'artistic talent', and at the same time, doing my job as a dentist to provide the best possible care.