Looking at a 3-D model of her teeth, Sara McClure didn't recognize her smile. The image her orthodontist had pulled up on a laptop didn't show her upper-row gaps—rather, it showed the perfect alignment that would be hers in 13 months.

"I saw my teeth as they were going to look," said McClure, a 31-year-old graphic artist in Eagle, Colo. She also got to view a start-to-finish progression of how the treatment would take place. So while her braces were on, she said, "I knew what to expect next."

Three-dimensional imaging technology has been making gradual inroads in the world of orthodontics. Traditionally, orthodontists put one-size-fits-all brackets and wires on crooked teeth and then modify the setup at appointments. It's a technique that involves a surprising amount of guesswork. But now several companies offer 3-D modeling programs that make it easier for orthodontists to diagnose underlying problems and give their patients more precise treatment.

Because the braces themselves can be customized, less trial and error is involved in straightening. And, early adopters say, patients require fewer visits to the doctor. But so far the technology is not widespread, in part because it can be expensive.

"As cost comes down, 3-D imaging will become the standard," said Dr. Lee W. Graber, president of the American Association of Orthodontists. "Right now it's still in its relative infancy. It's the same kind of change that happened in medicine when they went from 2-D X-rays to CT scans and MRIs."

Graber, who uses 3-D technology from a company called SureSmile, said that 3-D imaging was beneficial in several ways, starting with diagnosis. "We can see how all parts of the puzzle we are trying to fix fit together," he said.

Second, the technology helps the doctor build appliances—ither wires or Chiclet-like brackets—that suit a patient's needs. Finally, showing the patient an image of what his or her mouth will look like when treatment is finished is exciting, Graber said, and can improve communication between doctor and patient.

"It's taken the estimation part out of it," said Dr. Anoop Sondhi, an orthodontist in Indianapolis who uses a digital system made by 3M Unitek, for which he serves as a paid consultant. "Thirty years ago, we didn't have a good way of projecting exactly what movement would be accomplished with each adjustment. You made an adjustment, you see it worked out, and then you'd fine-tune it."

Not all adjustments move teeth optimally. For teenagers, that can mean more time in the chair; for parents, more half-days lost ferrying children to appointments. The 3-D technology may help.

"Most people think they'll have to go to 20 to 25 appointments," Sondhi said. "If I can cut that down to 12, that's less time you have to be bothered, and that's a huge deal."

The price can be huge, too. It costs doctors $250 to $1,000 more per patient to use 3-D forecasting and customized gadgetry instead of the standard plaster cast of misaligned teeth and off-the-shelf appliances. (Traditional braces, depending on alignment issues, cost $4,500 to $7,000.)

So some doctors charge more for the new technology. Others—like Al Bishop, the Colorado orthodontist who treated McClure—do not, because his patients are done with treatment faster. Sondhi also does not charge extra, partly because time-saving technology allows him to treat more patients, he said.

One of the first companies to introduce software that showed patients the final result was Invisalign, which sells tooth-straightening aligners that are an alternative to metal braces. In 2007, Invisalign introduced software that can predict how forces applied to teeth will move them.

Now, a different set of companies is competing to improve brackets and wires through 3-D technology. The one Bishop uses is called OrthoCAD iQ, which distinguishes itself by its computer-guided system for placing brackets on teeth.

A one-kind-fits-all bracket is typically put in the center of a tooth, but OrthoCAD iQ will sometimes put one "way off center" and get results, said Bishop, who has used it for four years. There's "no way humanly possible to know where to put that bracket" without this software, he said.

McClure, who paid $5,000 for her orthodontic treatment, recalled one of the special trays that helped place brackets on her teeth. "It sort of looked like a mouth guard made just for me that left my brackets behind," she said. "I had no idea it was going to be so easy."

A competitor to OrthoCAD iQ is a system called Insignia, which uses its own individualized brackets rather than off-the-shelf ones. Should a bracket fall off mid-treatment, Insignia makes it possible to replace it in the precise spot, which its manufacturer says other systems cannot.

Yet Insignia's adoption is spotty; no orthodontist in Manhattan provides it at this point. Dr. Jeff Kozlowski, a Connecticut orthodontist and paid consultant who helped develop the latest version of Insignia braces, has a theory on why. "It didn't take off upon entering the market," he said, "because it encountered the egos of orthodontists who feel that placing braces on the teeth is one of the most artistic things you can do."

He said he used to feel the same way. "What I learned is, my ego need not be challenged by using a computer for assistance," Kozlowski said. "It's about providing an artistic end result, not about placing brackets on the teeth."