Dentists have a saying among themselves: "There are more dentists afraid of children than children afraid of dentists." Some dentists, in fact, flatly refuse to have children in their offices. They are afraid the kids will scream and cry and make other patients nervous or that the children will wriggle and squirm, making it virtually impossible to work on their teeth.

But a growing number of dentists are now tailoring their practices to young patients. These pediatric dentists train for an extra two years after dental school just in the care of children's teeth.

There are an estimated 4,000 pediatric dentists in this country -- about twice as many as there were 15 years ago. These are dentists who love children and who have a way with them. And they are dentists who specialize not only in preventing dental cavities but in preventing dental fear -- a major factor in keeping adults away from the dentist.

"You would send your child to a pediatric dentist for the same reason you send your child to a pediatrician," said Dr. Michael Roberts, a pediatric dentist at the National Institute of Dental Research.

These dentists are specifically trained to deal with the special problems and needs of children and are well versed in treatments that children, but not necessarily adults, require. In addition, they have been taught to treat handicapped children. You can find a pediatric dentist by asking your pediatrician for a recommendation, he said, or by looking in the Yellow Pages.

Along with the rise of pediatric dentistry has come a whole new way of treating young patients, with an emphasis on prevention rather than the old "drill and fill" routine. Three key preventive tools are among the recent changes in dentistry that are affecting children most: fluoride treatments; sealants; early orthodontic care.

Fluoride treatments and sealants enable many children to avoid cavities altogether, Roberts said. Early orthodontia -- on children as young as 6 -- corrects problems while they are still easy to correct.

In addition, today's pediatric dentists are proponents of a new psychology of dental care that is resulting in a generation of kids who actually look forward to dental vists. "I don't believe there is a situation in which a child cannot walk out of a dentist's office and smile," said Dr. J. David Gaynor, a dentist in Sacramento, Calif., who is president of the American Academy of Pediatric Dentistry.

Although a baby's first tooth usually does not appear until the child is about 6 months old, teeth begin to form under the gums when the baby is still an embryo -- as early as the seventh week of pregnancy. Parts of all 20 primary teeth, or baby teeth, are formed by birth. Just after birth, the permanent teeth start to form.

Gaynor recommends sending children to a pediatric dentist early -- certainly by age 2, and even earlier if parents suspect that the child's teeth may need attention. "Preserving your child's primary teeth is the best single thing you can do to help your child avoid orthodontia," Roberts said.

The baby teeth hold spaces for the permanent teeth that will replace them and help guide the permanent teeth to the correct positions. The major problems with childrens' teeth, he said, are cavities, misaligned teeth and trauma, such as knocking a tooth out. Periodontal disease is not a serious problem for most children.

The children who may have to see a dentist even before their second birthday frequently are those with "bottle caries" -- cavities that arise in infants or young children who fall asleep sucking on a bottle. "Bottle caries are my biggest problem," said Dr. Charles Broring, head of pediatric dentistry at Georgetown University School of Dentistry. They are caused by the pooling of sweet fluid in the child's mouth and generally occur when a child is between about 8 months and 3 years old.

A child who sucks a bottle while awake does not have this problem because saliva bathes the teeth and washes away the milk, formula or juice. During sleep, the child's tongue protects the back teeth, but the front teeth are fully exposed to the fluid from the bottle. So the bottle caries form on the front teeth. These cavities are entirely preventable -- parents should never allow a child to take a bottle of milk, juice or formula to bed. Bottles of water are okay.

Frequently, Broring said, "parents will come in because they want their child's teeth to look better. The child's front teeth will be yellowish or gray or brown. The parents have no idea that what is really wrong is tooth decay."

Bottle caries must be filled, he said. The cavities are caused by bacteria, and if the bacterial infection is not stopped by filling the teeth, it can spread to the area above the mouth. Although most children are treated before the infection becomes rampant, some are not.

"We've seen some seriously ill children who have needed to have their teeth pulled and to be hospitalized and given antibiotics," Broring said. Others, with less severe decay, nonetheless may have to have stainless steel crowns put on their teeth because the teeth are too far gone to hold a regular filling.

To prevent the typical cavities of childhood, dentists recommend fluoride treatments, where the dentist applies fluoride directly to the child's teeth. For additional protection, some dentists also suggest that children rinse once a day with a fluoride-containing rinse. Fluoride "inhibits the growth of bacteria," Broring said, "helps re-crystallize tooth enamel, and seals small lesions."

But fluoride is most effective in protecting the smooth surfaces of teeth. The grooves of the chewing surfaces are helped the least by this treatment. However, Roberts said, "where fluoride is least effective is exactly where sealants protect."

Dental sealants are made of resins similar to those used in other dental procedures, such as repairing the edges of broken teeth, and actually form a protective barrier over the pits and grooves of teeth where most cavities start. Sealants are not new, but until recently they were not widely accepted by dentists or insurance companies. Children tend to get many cavities around age 7 to 9 and when they are teen-agers, but if their teeth are sealed, these cavities may never occur. A number of NIDR studies involving thousands of children show that sealants result in about an 85 percent reduction in tooth decay.

No one knows for sure why cavities start at these ages, but the conventional wisdom has been that young children eat a lot of sugary foods and teen-agers eat all the time. The result, in both cases, would be to encourage the growth of decay-forming bacteria. However, according to NIDR's Bruce Baum, it is also possible that the hormonal changes in children and teen-agers may alter the makeup of their saliva, making their teeth prone to decay.

Saliva contains minerals and at least half a dozen antibacterial components that are essential for healthy teeth. Almost anything can alter adults' saliva, including hormones and hundreds of commonly prescribed drugs. It is "reasonable," then, Baum said, to suspect that some cavites are simply beyond youngsters' control.

Dentists apply sealants by first cleaning the chewing surfaces of the teeth with a mild acid. This treatment creates "millions of micro-indenations on the tooth's surface, which the sealant sticks on," Roberts said. Then the dentist paints on the sealant, which resembles clear or white nail polish. Sealants remain on the teeth for years -- in one study, 85 percent of sealants stayed on for nine years. When sealants do come off, they come off in pieces. Children generally do not realize when their sealant comes off, but dentists can see when a part of a sealant is gone.

When sealants were first introduced in the early 1970s, dentists and insurance companies questioned whether they were effective in preventing cavities. They also wondered what would happen if they fall of or if the dentist inadvertantly put a sealant on a tooth that has a small cavity just starting on its surface. Will the cavity under the sealant get bigger and bigger?

Experience with the technique has shown that if a sealant falls off, the minerals in the saliva quickly fill in the tiny cracks made by the mild acid treatment, so the tooth remains sound. And if a tiny cavity is sealed in, it stops growing because the bacteria that produce the cavity die for lack of oxygen.

The American Dental Association and NIDR encourage the use of sealants. Dental insurance plans, including Connecticut General, Aetna, Travelers and John Hancock, pay for children's teeth to be sealed. The federal Blue Cross plan does not cover sealants; neither do Group Health Association and Kaiser-Permanente, two of the largest local health maintenance organizations.

Adults with fillings in their teeth are not candidates for sealants because the sealants do not stick to the filling material. And an adult who has never had a cavity in a molar is an unlikely candidate for sealants; such people are probably especially resistant to cavities anyway. For this reason, sealants are not cost-effective in adults.

According to the American Dental Association, the average cost of a sealant is about $11 a tooth.

In addition to sealing childrens' teeth, dentists are starting to treat misaligned teeth earlier and earlier so that now 6- and 7-year-old children are wearing braces and "head gear," a device with a strap that goes around the head. Orthodontists use head gear, said Roberts, to hold the top permanent molars back while the child's face grows, thereby correcting buck teeth.

And braces these days are not so noticeable because orthodontists have begun bonding tiny brackets directly on the teeth instead of wrapping the teeth in metal bands. The bracket is often made of clear plastic, especially for front teeth. The result is not only less of a mouth full of metal but also teeth that are easier to clean and to care for.

"Years ago we waited until the child was 10 or 12 before starting orthodontia," Broring said. "Now we are more interested in heading off problems." Roberts agrees. "Instead of letting the child go on with crowded and jumbled teeth, we intervene early," he said. "It takes longer to correct the problems when the child is older and the child has to go through years of having unattractive teeth." In addition, if a child has buck teeth, the teeth are more likely to be broken in a fall.

Sometimes, children may get all of their orthodontia over with early and at other times they may need a second round of braces after their teeth stop growing. But the consequences will be more attractive teeth and faces as well as healthier teeth. And, said Roberts, the cost of starting orthodontia early is no greater and can be less than starting it later.

With sealants and orthodontia and regular check-ups starting at age 2, pediatric dentists are recommending a lot of dentistry. So it is all the more surprising that children tend to enjoy their visits to the dentist. The secret, pediatric dentists say, is to treat the young patients with sensitivity and respect.

A method that they call "tell, show, and do" is highly effective, they report. "Say I'm going to clean a child's teeth," said association president Gaynor. "Rather than just putting the child in the chair and beginning, I take the rubber cup that I use to clean teeth and run it over my own thumbnail. Then I ask the child to run it over his thumbnail. Most children are willing to give it a try. Then they realize this isn't so bad."

Broring said he builds a good relationship with children by going slowly, interviewing them in his office on the first visit, for example, rather than thrusting them in the dental chair. "I treat the child as a person," he said. "They sense this quickly. Shaking hands with a child is a big event. That simple gesture can mean a lot to a small child."

Pediatric dentists also avoid words that can scare children. "We don't pull teeth, we wiggle them out," Broring said. "We don't give a shot of novocaine, we put the tooth to sleep or we numb the tooth."

Roberts tells very young children that the drill is a fire engine. It makes a high-pitched whine and it squirts water. Roberts' drill is even equipped with a light which he calls a headlight.

This is not to say that there is never any pain or discomfort or that children never get cavities anymore. But, say the pediatric dentists, children who are treated with respect can take the discomfort and come out smiling and proud of themselves.

Children who are taught how to take care of their teeth frequently do a good job of avoiding sugary foods, brushing and flossing, and even, when indicated, rinsing with a fluoride-containing rinse. "Children want to take good care of themselves," Broring said. And with these new approaches and technologies, it is easier than ever to encourage them to do so.