FIT FOR A SMILE

According to history, George Washington was fitted with two partial dentures and three full dentures. Legend has it that all of them were carved from wood by his dentist, which is probably why the first president of the United States had to have five sets of dentures during his lifetime.

Today, using space-age materials developed by the National Space and Aeronautics Administration (NASA), dental labs and technicians now manufacture full or partial dentures that will usually outlast the patient.

The practice of dentistry can be traced as far back as the Egyptians, around 3,000 B.C. But the development of dentures to replace extracted teeth is a relatively recent development, dating back only several hundred years. In fact, the use of polymerized acrylic resin as a base for artificial dentures and teeth was introduced in the United States in 1935.

The phase of dental science that deals with various methods of providing artificial substitutes, or dentures, for missing teeth is called prosthodontics. It deals with the artistic (aesthetic), mechanical and physiological aspects of dental restoration.

Cape Girardeau dentist Dan Cotner said the replacement of missing teeth is important for proper chewing of food, speech, and for physical appearance. Replacement of missing teeth is also important for the even distribution of the forces involved in chewing, which prevents the loss of additional teeth because of added stress on the remaining teeth.

Dentures include fixed bridges, partial dentures, or full dentures. They may be placed in the upper or lower mouth or jaw, or both.

The first step in the manufacture of dentures starts in the dentist's office. After the teeth are extracted, the dentist makes an impression of the upper and lower jaws of the patient's mouth. This impression, along with a written prescription, is sent to the dental lab. The prescription contains written and illustrated directions for the dental lab technician to follow in building the dentures.

Terry Huckstep, a local dental lab technician, said dentures can only be made under the specific and written authorization of a dentist or oral surgeon. Said Huckstep: "For every denture completed, or under construction, in a dental lab, there must be a written prescription made out by a dentist. That's state law. Each prescription has a control number, and all prescriptions must be kept on file for a number of years."

Cotner said in a couple of states (but not Missouri), trained denturists may take impressions of the patients' gums, but are not permitted to do any other dental work.

"Sometimes it may take several visits before the final fitting is ready to go to the lab," said Cotner. "I always recommend the patient bring his or her spouse, a family member, or a close friend with them so they can see the fitting."

To make the initial impression, Cotner uses a space-age material developed for the NASA space shuttle program. The material is the same used to manufacture the "O" ring in the shuttle's solid rocket booster.

Huckstep said when the impression or tryout arrives at the dental lab, a wax mold or impression is made and mounted on an articulator. The articulator simulates the up and down, and side movement of the human mouth and jaw. The lab technician mounts the specified number of artificial teeth in the mold according to directions on the dentist's prescription form.

There are 28 teeth, plus wisdom teeth in an adult. The lab technician can replace all 28, or as many teeth as directed by the dentist. All teeth are numbered, from the right side of the jaw to the left.

"The dentist is the man (or woman) in charge. He is like the architect building a house. He prepares the plans. It's our job to carry out those plans and build for him and the patient a custom-fitting set of dentures," said Huckstep.

Using the articulator, the lab technician can determine if the teeth are located in the proper position and if the bite is correct. "If you can bite your fingernails with dentures, you've got a good fit and bite," Huckstep quipped.

To get the proper fit, the dental technician must measure in millimeters. After the artificial teeth -- made of a modern, hard acrylic plastic -- have been inserted in the wax mold, the technician uses tools to fashion the wax around the base of the teeth to simulate the tissue of the gum and jaw.

After the wax denture or "try-in" is completed by the lab, it is sent back to the dentist for a final fitting in the patient's mouth and any needed adjustments. If the fitting is correct and the patient is satisfied, the try-in is returned to the lab where the wax impression is used to make the final, acrylic dentures.

Huckstep said artificial teeth are made in shades of whiteness, according to the age of the patient. Older patients usually have a darker shade of teeth inserted in their dentures to simulate aging, while younger patients have a brighter shade to simulate newer and younger teeth. However, Huckstep said he has had older patients ask for the brighter shade of teeth.

The dental lab can also put in gold caps, inlays or fillings on the artificial teeth to make the denture appear even more natural looking.

Huckstep said he has made dentures for the very old and the young. One was a 97-year-old woman. Another was a teenage girl, who had most of her permanent teeth in place. However, several baby teeth had been lost, but the permanent teeth had not come in. A partial plate was fitted for her until the permanent teeth came in.

In life, dentures provide a comfortable and aesthetic lifestyle for the patient. In death, dentures are sometimes the only means of identifying the victims of a fire or other major disaster.