How do you go about matching a tooth's shade?

The patient shown in the picture has his two central incisors crowned. His shade was fairly easy to match but some are not. Most dentists use dental shade guides to help them choose a shade or shades for a tooth. For most posterior teeth the process that is fairly simple. When choosing a shade, I hold a shade guide adjacent to the tooth in question and look at it briefly, then I choose an alternative shade and look briefly at them next to the tooth.

When evaluating shade buttons the dentist should look at the shade for no more than a second or two at a time. If the shade guide is held against the tooth for longer it starts looking better since our eyes accommodate and we can no longer adequately judge whether the guide used is the correct for a patients tooth. In general I can choose a shade after looking at two or three alternative choices. I also let my patient view my shade button 'challenges' while I'm doing them.

For a shade to look acceptable it must not only match the hue and chroma (color) of the tooth but should be close in value( brightness). If I want to judge the value of a shade I sometimes squint while looking at it, since this essentially eliminates the color component of the shade but still allows me to perceive the black and white portion of the shade( the value).

For anterior teeth the process of picking a shade (or shades) can sometimes be extremely tricky. For tricky shades a dentist or dentist can draw out a shade map on his lab Rx that shows the different sections of the tooth surface and indicate what shades he sees in different zones of the the tooth surface. Also for tricky anterior teeth I often send photographs of the tooth or even send the patient to the laboratory for their shade selection. Sometimes after a crown try in, if I feel it is necessary my patient is sent to the laboratory either custom staining of their crown or so that the ceramicist can view how the crown looks in the mouth and have a better idea of what changes need to be made. For some single anterior teeth being made for discriminating patients or dentists, a ceramicist may even have to make remake the crown several times, before a satisfactory version is fabricated.

Where are you spending your vacation?

I am currently taking a break in Woods Hole, Massachusetts in Cape Cod. I have been spending time every summer here for over over fifty years. Aside from some beautiful coastline, Woods Hole is home to the Marine Biological Laboratories, The Woods Hole Oceanographic Institute and the NOAA Fisheries. Although it is clearly a world renowned center for marine scientific research, I go there mainly for two weeks of R & R. My activities include swimming, biking, sailing, visiting with old friends, cook outs. I will return to my New York Dental office on September sixth. with my batteries recharged.

What is the thin grey line I see above (or below) my crown?

Usually when I am asked this by a patient I find is they have a porcelain fused to metal crown that has been finished on the outside with a thin metal collar. This is usually done to create a finer margin for the restoration and can help insure that the crown fits optimally and the porcelain doesn't get cracked when the crown is seated.

The obvious follow up question that patients ask is why not cover the margin with porcelain in the first place? I usually choose not do this with my posterior restorations since I find that when my crown margins are covered with porcelain it can cause the crowns to fit too tightly since porcelain shrinks when it is fired and this can put pressure on thin and flexible metal that supports it at the margins. When trying in crowns with no metal collars it can sometimes cause the porcelain to 'pop' off and leave the porcelain with a chip.
If the technician chose to make the metal at the margin thicker than this wouldn't be as much of a problem, but the resulting crown would have a noticeable 'ledge' at the margin and could become a plaque trap.

I usually specify that my dental lab use a thin 'hairline metal collar' on the buccal of all my porcelain fused to metal crowns. This tiny metal margin is not usually noticeable since it has the thickness of one or two hairs and is subgingival. If a patients gums eventually recede it may become visible.

If a patient doesn't desire to have a grey line, they may consider a different type of crown (Lava, Emax, Procera, Empress) but often these crowns can be less strong or be more cement dependent than a porcelain fused to metal crown fabricated on a tooth with a bevel preparation. Although not all dentists probably will agree with me, I find that cement dependent restorations have less initial retention and tend to be more dependent on their cements to keep them attached to their teeth. If a crown is 'cement dependent' it has one more thing that may fail and often the cement is the weakest component of the restoration. It can separate either the tooth or the restoration. I have found that this can make some of these crowns more likely to become loose or come out down the road. Metal free esthetic restorations tend to have larger gaps between them and the tooth and are more likely to fail in the long run.

The pyramids were built without any cement and they have lasted for thousands of years. In my opinion, The cements used to lute pfms to teeth tend to seal up the tiny gaps between the metal and the tooth and do a better job in resisting the forces that might tend to dislodge a crown.

What is the new New York State AED Law for Dentists?

The New York State legislature recently passed a law mandating that each New York Dental Facility is required to have a AED device. This law takes effect January 1,2012 and now is a good time for offices to purchase a unit. Plan ahead and don't wait until the last moment. We purchased our unit from good friend Jon Bloomberg of Core Medical Systems. He offered me a good price and he offered a good selection of units and explained the differences to me. He will give us a free in-service to our staff to help familiarize us with the unit. If anyone is interested in contacting him they can at:347-995-4461.

What is that metalic looking thing that I can see on the radiographs above the patient's maxilary incisors?

This is a question I am asked every so often by one of my hygienists. Lately more often. Most of the time when I am asked this question it turns out to be that the patient in question has a nose piercing. A nose piercing usually will appear on maxillary anterior radiographs as a wire with a small ball attached.

Sometimes wires seen above teeth on periapical radiographs can be due to other causes. Seeing a metal wire in what appears to be maxilary bone can also sometimes be a tell tale sign that a patient has previously either brokent their jaw or had maxillofacial bone surgery to reposition the jaw. Surgeons can leave the wires in place after a surgery and they show up on radiographs.