Patients Putting on Happy Faces Through Dental Bonding

As a deputy mayor of Los Angeles, Tom Houston is accustomed to getting his picture taken frequently with celebrities, visiting dignitaries and other public officials.

But he had never been comfortable with the way he looked in those photographs. Yellowed teeth and a gap separating his upper front teeth, Houston said, made him feel self-conscious. “I developed a habit of smiling with my mouth closed,” he confessed recently.

But no more. Houston, 40, is now smiling with his mouth open. The gap is gone, and his front teeth look brighter and shinier, their appearance improved by a technique called bonding. After his make-over, which lasted a few hours, Houston held a mirror to his face and said matter-of-factly: “I look a lot better.”

Like Houston, many people born with less-than-perfect smiles are finding that bonding can help change their looks--and sometimes, they claim, even their outlook on life. In the past several years, cosmetic bonding has been done on about 6 million teeth, according to Dr. Frank Faunce, an associate professor of pediatric dentistry at Emory University School of Dentistry in Atlanta and a bonding expert.

Bonding is a general term used to describe a variety of techniques to attach materials to the tooth surface. It was introduced about 30 years ago after the development of an adhesive material used then to repair fractured teeth and to seal teeth and prevent decay.

As materials and techniques improved, cosmetic bonding was born. Today, it can be done directly or indirectly. In direct bonding, a technique that became widely available in the early 1980s, liquid plastic materials are placed on the tooth and shaped to the desired proportions. In indirect bonding, a procedure that has become available only in the last year or so, a preformed shell (veneer), usually made of porcelain, is bonded to the tooth’s surface.

Disguise Defects

Both types of bonding can disguise a multitude of dental defects relatively quickly, proponents say. Bonding can help close gaps between teeth, repair chipped teeth and lengthen teeth to more pleasing proportions. It can also whiten teeth that have been stained by the antibiotic tetracycline or that have yellowed with age.

The techniques can sometimes take the place of more expensive and extensive procedures such as a crown (cap), and some adults opt for bonding in lieu of braces.

Bonding isn’t a panacea, however, as even dentists who perform the procedure point out. “Bonding materials are not as color-stable as conventional crowns,” said Dr. Sam Contino, a Pasadena dentist. The potential long-range side effects of bonding materials--considered foreign substances--are not yet known, he added, and a bonded tooth is not as strong as a crowned tooth.

The costs of bonding vary widely, as a survey of four Southern California dentists shows. Costs for direct bonding range from $75-$450 per tooth; for indirect bonding, $250-$500 per tooth. (Their costs for a crown, in comparison, ranges from $415-$600.) Typically, bonding is done on four to eight front teeth--the ones most noticeable when a person smiles--but sometimes patients choose to have additional teeth bonded. Dental insurance does not normally reimburse for cosmetic bonding.

In direct bonding, generally done in one appointment, the dentist prepares the tooth by roughening the enamel, the hard outer coating. A weak acidic solution is applied to the tooth’s surface and is then washed off. “That’s done,”Dr. Roger Lewis, a Beverly Hills dentist explained, “to create tiny pores on the tooth so the bonding material will stick.”

Next, a liquid plastic bonding material, or resin, is applied to fill in the “pores” and achieve the initial bond. Then the dentist applies a thicker plastic material to the tooth and shapes it. When the desired shape is achieved, he uses an application wand with a special light to activate a catalyst within the plastic and harden it. Finally, the new tooth surface is polished.

Thin Shell Made

Indirect bonding generally requires two appointments. During the first, the dentist roughens the enamel and then takes an impression or mold of the teeth. The mold is sent to a dental laboratory to be used in making the veneer, a thin shell that resembles a false fingernail.

During the patient’s next visit, the tooth surface is cleaned, a weak acidic solution is applied and then rinsed off, and a liquid plastic material applied. Finally, the veneer is positioned and hardened with the special light.

After a brief adjustment period, most patients don’t notice the presence of the veneers. “They look and feel exactly like your own teeth,” said Brenda Viereck of Van Nuys, who had indirect bonding done on four upper teeth.

Although dentists claim both procedures are virtually painless, most offer patients local anesthesia or nitrous oxide (“laughing gas”).

The life of the shiny new teeth depends, in part, on a patient’s oral hygiene along with eating and drinking habits. Most dentists caution patients not to eat ice chips, which can weaken the bonding materials. Others outlaw such foods as apples. Coffee, tea and tobacco will stain bonded teeth, although the stains are more likely to come off bonded with the veneers.

Follow-up dental care also is important. “These materials can chip, stain or become debonded,” said Dr. Richard J. Hoard, chairman of operative dentistry at the UCLA School of Dentistry who advises annual checkups for bonded teeth. “The seal can break, especially if it’s not done correctly.”

Patients who follow these suggestions can expect teeth bonded by the direct method to stay in good shape about three to eight years, experts said. Teeth bonded indirectly with porcelain veneers last anywhere from five to 20 years. (Crowns, in comparison, usually last anywhere from five to 20 years.)

Most dentists caution patients to consider the process irreversible. “In general, it should be considered irreversible,” said Dr. Mark J. Friedman, an assistant clinical professor of restorative dentistry at the USC School of Dentistry and a Sherman Oaks dentist. “That’s because small amounts of enamel usually have to be removed to develop proper contours. In certain situations bonding can be removed and not replaced.”

Other dentists disagree. “In the majority of cases, it’s reversible,” Lewis said, adding, “it’s a moot point because it never happens. You would never want it off once it’s on.”

Not everyone is a good candidate for bonding. People with active gum disease or whose teeth have insufficient enamel left should probably forgo bonding. Those with a tooth-grinding habit or “hard bites” that would put undue pressure on bonded teeth are not ideal candidates either. Teeth with crowns can’t be bonded.

“Porcelain veneers should not be done on persons under age 18,” Friedman said. “There are still too many changes in the gums. The teeth are still erupting and changing.”

Given the materials available now, direct bonding is best limited to upper teeth, dental experts add, since lower teeth are in frequent biting contact with the upper teeth and might wear away bonding. One option for patients in need of bonding on upper and lower teeth is direct bonding of uppers and indirect bonding of lowers.

In the future, dentists predict, the development of even stronger materials will make bonding more durable. A newly developed ceramic veneer looks especially promising, according to Faunce. “It’ll have the same abrasion resistance as normal tooth enamel,” he said.

Faunce believes prices will drop in years ahead as materials become cheaper, but other dentists disagreed. Patients are paying not so much for materials, they pointed out, as for laboratory work and the dentist’s time and expertise.