Photography by S. Peter Lopez
In orthodontist James Mah’s office, Jonathan Romero and his father, Jorge, review old X-rays showing the boy’s severely impacted tooth, now corrected thanks to innovative virtual technology developed at USC.

Issue: Spring 2003

Say ‘Ah!’

USC's School of Dentistry has been making some adjustments to its academic bite — treatment mapped by a management theory-minded dean, probed by ingenious basic and applied scientists, re-aligned with a paradigm-breaking pedagogical idea and crowned by rounds of unconventional clinics.
By Carol Tucker

Jonathan Romero groans as he recalls the constant toothache in his lower jaw from less than a year ago. Now it “only hurts a little,” says the 11-year-old boy in the baseball cap, shrugging it off as no big deal.

Jonathan sits with his father in the waiting room of the USC School of Dentistry’s Orthodontics Faculty Clinic, whose tan walls and couches are by now very familiar to them both. For almost eight months, they visited this office once every week or two, as orthodontist James Mah, a specialist in craniofacial sciences, laid the groundwork for a complicated and potentially risky procedure to fix Jonathan’s toothache.

While Jonathan waits quietly, his father explains what brought them here. Speaking in Spanish to Lupé Cadena, an administrative assistant in the orthodontics department who often fills in as interpreter, Jorge Romero tells how he first realized that Jonathan had a serious problem. “It seemed like my son was having pain as one tooth was growing out. But we couldn’t see the tooth,” says Romero, a maintenance worker for USC’s Housing Services department.

X-rays showed Jonathan had an impacted tooth lying sideways under the gum in his lower jaw. Complicating matters, a cyst had developed in the tissue around the tooth; as it expanded, the growth put pressure on the adjacent premolars. Over time, the cyst actually displaced the premolars.

Knowing he was out of his depth, Jonathan’s family dentist referred the case to Mah, an expert in craniofacial dentistry. The specialty focuses on anomalies of the head, face and neck, and overlaps medicine and dentistry. From conventional X-rays alone, it was difficult to locate Jonathan’s impacted tooth and the cyst relative to his other teeth and the structures of his jaw. So Mah turned to something unconventional – a new three-dimensional imaging technology that enables a clinician to virtually reconstruct the patient’s mouth inside and out.

The technology, combined with a customized computer program, produces highly accurate 3-D images of the patient’s head and neck. Now being developed at the school’s Craniofacial Virtual Reality Laboratory, it employs virtual reality to advance dentistry, and not just in the laboratory. Such futuristic tools are being used to assist craniofacial dental specialists, orthodontists and surgeons in diagnosing and treating patients like Jonathan Romero.

Mah used the imaging technology to isolate the position of Jonathan’s impacted tooth and pinpoint its proximity to surrounding structures: other teeth, nerves and bones. Armed with this information, Mah could make a definitive diagnosis and plan the boy’s treatment in fine detail, including surgery to expose his hidden tooth, then orthodontia to move it to the best possible position. In the hands of Jonathan’s dental surgeon, the same information became a blueprint for mapping the operation.


Dean Harold Slavkin stands in the hallway of the school he envisions as a “learning organization” where “all members are always involved and engaged in the act of learning.”

The CVR laboratory – a collaboration among the School of Dentistry, the School of Engineering and the Keck School of Medicine of USC – is among the most advanced virtual imaging centers for craniofacial dentistry in the nation. Directed by Mah, the lab has pioneered various imaging techniques to create realistic and accurate models of the patient’s head and neck. And these models are dynamic, employing animation to plot the movements of the jaw.

“Our ultimate goal is to create a patient-specific model that can be used for a number of functions, including diagnosis, treatment simulation, treatment planning, hypotheses testing, and design of better crowns and other appliances,” Mah says.

The CVR laboratory vividly exemplifies the USC School of Dentistry’s reinvention of itself as a “learning organization,” an identity christened by dean Harold C. Slavkin and embraced by the school’s faculty and staff. Slavkin drew his inspiration from MIT organizational theorist Peter Senge, who coined the term in his 1990 book The Fifth Discipline, which summarizes his revolutionary management philosophy. The essence of the “learning organization” is its ability to respond to change, crucial at the dawn of the new millennium.

Slavkin, who was appointed dean in 2000 (he previously had been director of the National Institute of Dental and Craniofacial Research), saw it as the right vision for the school where he’d been a professor since 1968.

“In the learning organization,” he explains, “all members are always involved and engaged in the act of learning, whether they are faculty, students, staff or alumni – exploring concepts, research and how to think and analyze things differently.” He grows passionate as he outlines the unifying principle and driving mission of his school. It’s a vision that applies across the board – to technological advancements, to methodological innovations and discoveries, to new ways of teaching, even to providing public oral-health care and health education for Los Angeles and beyond.

As a learning organization, the USC School of Dentistry is one of the first in the nation to transition from a traditional curriculum to problem-based learning. Evidence suggests the more dynamic, inquiry-based approach fosters critical thinking and promotes lifelong learning. Students graduate prepared to practice the dentistry of today and willing to keep learning the dentistry of tomorrow. The change involves the entire school, as classes and departments are integrated, and faculty learn a new way of teaching. The challenge, Slavkin explains, is to always consider “the future of what is thought, what is taught, and what is practiced in the oral-health profession.”

Emphasis on “future.” A vintage photo from 1914 shows white-coated USC dental students bent over neat rows of patients, a clinic arranged along industrial-age notions of efficiency and uniformity. But those days of cookie-cutter, drill-and-fill dentistry are gone. Today’s dental students work in private cubicles, and they don’t always wait for patients to make an appointment. They hop into special vans, called mobile dental clinics, and whisk their services to homeless shelters, urban schools or rural areas where oral care is scarce. They approach patients as people, not disembodied mouths. They adapt high-tech tools to an ancient art, borrowing from bio-engineering, telemedicine or materials science if it leads to better research, better diagnostics or better treatments. They master dentistry case by case, rather than by rote memorization. And they view training not as a four-year prelude to practice, but as a lifetime endeavor.

This innovative spirit isn’t about the dental school wanting to claw its way up the rankings ladder. USC already is near the top of the list of private dental schools based on funding received from the National Institute of Dental and Craniofacial Research (10th among all American dental schools, public and private). It also shows consistently well on a list of high-impact universities based on cited publications frequency in dentistry-oral surgery and oral medicine. And while American dental schools do not participate in beauty contests such as the U.S. News & World Report rankings, in a recent academic peer review USC finished among the top 10.

It’s not about being perceived as better. It’s about really being better, about leading rather than following.

In the realm of virtual technology, the school’s CVR lab has indeed put USC at the forefront of improving diagnosis and treatment of impacted teeth. The emerging process – called 3-D volumetric imaging, or 3-D visualization – also has potential uses for training surgeons, exploring treatment options with patients and helping patients to understand procedures and visualize outcomes.

While many of these applications are still in the future, Mah believes 3-D imaging has the most immediate clinical value in cases such as Jonathan Romero’s, where traditional radiology leaves dentists and surgeons making educated guesses about the impacted tooth’s exact position. This means that surgeons must sometimes do more invasive work, increasing the risk of damaging nerves, blood vessels or other vital structures.

“We’ve demonstrated in a small number of cases that virtual reality can make a difference for these patients,” Mah says.

Virtual reality dentistry is receiving widespread attention nationally and internationally. The Los Angeles Times splashed it across the front page of its July 15 “Health” section last summer, noting that USC is on the brink of “creating a virtual craniofacial patient, the 21st- century version of a crash-test dummy.”


Mah, with a virtual model of the lower jaw. His lab developed 3-D technology that assembles 600 or more scans into a see-through skull.

Mah – who is forever good-natured and accommodating despite a hectic schedule of patients, research commitments and lectures – has been spending time on the lecture circuit, spreading the word about 3-D volumetric imaging at New York University, the University of Michigan and dental and orthodontics associations across North America and Asia.

Most dentists and craniofacial surgeons rely on photographs, X-rays and stone models – crude tools that require clinicians to “visualize” much of a patient’s treatment. Commercial software offers a way to “stack” the images and rebuild them to create a 3-D representation. While a handful of other dental institutions use digital information captured through 3-D dental cameras, USC alone has developed customized software for dental applications (Mah’s lab built a hybrid from various programs) and USC alone has constructed a virtual model.

Called the Virtual Craniofacial Patient, this model lets the dentist build an accurate, full-sized likeness of a patient’s mouth with the help of a computed tomography (CT) scanner, a kind of 3-D camera. The model can map the patient’s whole upper and lower jaw from various perspectives and even show the volume of the jaw. Images can be sliced and diced any way to isolate a problem area. Surgeons can use these scans to plot different treatment options, predict outcomes and explain procedures to real patients.

“3-D volumetric imaging has great potential in the future of dental care,” says Mah, who first began investigating the technology as a doctoral student at Harvard.

USC dental surgeon Michael Jorgensen couldn’t agree more. He has used 3-D imaging in six surgeries – including young Jonathan Romero’s – to uncover impacted teeth in preparation for orthodontics.

With conventional X-rays, even in the best-case scenario – when impacted teeth are clearly visible on the two-dimensional films – “the positioning of the third dimension is generally uncertain,” Jorgensen says. 3-D imaging virtually uncovers the tooth, adding a degree of precision never before possible.

Most often, Jorgensen’s job is to expose the impacted tooth so it can later be moved to its proper position. Such surgery can be tricky because teeth lie deep within the jaw. To reach them, a surgeon must remove both soft tissue and bone.

Jorgensen recalls a 12-year-old girl who was missing her upper right canine tooth. Conventional radiographs showed the tooth impacted in the upper jaw, but they didn’t show whether the tooth was closer to the roof of the mouth or the outer surface of the jaw, facing the lip.

3-D imaging revealed the canine lodged near the palate and hugging the root of the right lateral incisor. By virtually removing layers of soft tissue and bone on the computer model, Jorgensen was able to plan an exact surgical route for uncovering the real tooth.

“The surgery then became very straightforward,” he says. “We could expose the crown of the impacted tooth while removing a minimal layer of bone and avoiding the root of the lateral incisor.”

Jeff Lee DDS ’02 was one of the first orthodontic patients to benefit from USC’s virtual reality capabilities. His upper and lower incisors jutted out badly, causing him to feel self-conscious about his protruding lips. As one of Mah’s students, Lee knew he could benefit from orthodontic treatment but wondered whether it was worth the trouble. How much would the position of his lips actually change?

Using the latest 3-D imaging techniques from his research laboratory, Mah offered Lee a sneak preview. The demonstration not only convinced Lee to go ahead, but helped him brace for a frightening treatment plan: Four wisdom teeth and four molars had to be pulled; then would come braces. Along the way, Mah took further 3-D images to track Lee’s progress.

“It’s reassuring to be able to picture the result and know what’s going on,” says Lee, now a practicing dentist.

Mah relies on computer scientists from the USC School of Engineering’s Integrated Media Systems Center to assemble realistic virtual models of his patients. In the CVR lab, engineering and dental graduate students tirelessly manipulate CT scans to build a dummy patient on screen. They segment the lower and upper jaw to animate the image, showing the dummy’s bite. As they stack digital slices of the mannequin’s head, the dummy becomes fully dimensional, a see-through skull. A high-quality model requires no fewer than 600 scans.

When the craniofacial modeling goes beyond the scope of dentistry, the lab also works closely with plastic surgeon John Meara from the Keck School of Medicine of USC.

Meara, who specializes in repairing craniofacial head and neck anomalies, says the technology has “huge implications” for diagnostics, treatment planning, surgery and follow-up. He envisions using virtual patients to simulate treatment and outcomes of children born with cleft lips or palates. In the case of babies born without an ear (a condition called microtia), rather than fashioning a crude artificial ear, Meara envisions relying on an inverted 3-D model of the child’s healthy ear to construct a perfectly matched prosthetic mate.

The Virtual Craniofacial Patient has great potential as an educational tool for training surgeons, too. In the collaboration with IMSC, the lab is studying the possibility of combining 3-D virtual images with haptic feedback – meaning the computer would simulate the feeling of surgery. “Within a year, the addition of virtual touch to the technology will allow USC medical and dental students to put on gloves and feel the texture and resistance of slicing through skin and bone on various types of surgeries before performing them on actual patients,” the Los Angeles Times predicted last summer.

As of last November, however, it was still too early for champagne toasts. “We’re not quite there yet,” says Meara. “We have the bits and pieces. It’s just a question now of taking it to the next level.”

Breakthroughs in research, treatments, techniques and technology call for a rethinking of the role of the family dentist. Here, too, USC’s School of Dentistry is proving itself to be a trendsetter, becoming one of the first two American dental schools to make the leap to problem-based learning. A critical goal of this emerging pedagogy is to produce dentists who are “lifelong learners,” explains Charles Shuler, the school’s associate dean of academic affairs.

His ponytail suggesting a touch of unconventionality, Shuler isn’t the most obvious point-man for the dental school’s transition to a new pedagogical model. His administrative post aside, Shuler is a basic scientist: a chaired professor and head of the school’s prestigious Center for Craniofacial Molecular Biology. His enthusiasm for PBL is perhaps best understood in this light.

In a traditional curriculum, he complains, basic science courses are disconnected from practical experience: the old scholar-practitioner schism. Students trained the old-fashioned way attend lectures during their first two years of dental school and memorize content. In their third year, they begin clinical work.

In problem-based learning, students get hands-on clinical experience right off the bat, generally assisting upper-level students or handling simple procedures like scaling and oral exams. As learning progresses, they gradually increase their skills and take on more ambitious clinical assignments. From the start, students solve real problems and master real skills for treating that particular problem (in a simulator lab). Cases drive all curricular content, whether they involve basic science or clinical practice.

“In PBL,” Shuler says, “students discover topics of learning by studying cases, which then leads them to the knowledge they need.”

Shuler likens PBL to the steps a practicing dentist follows with a real patient. After the case is described, students identify the facts (“what we know”); generate ideas about the problem based on these facts (“what we think”); and then identify the skills and science necessary to solve the problem (“what we need to know”). The cases are carefully written, reviewed and revised by faculty to cover the necessary curricular content. While students study one case at a time, that case could draw upon 15 different subjects. By the time they graduate, PBL students will have mastered about 75 published cases – not to mention the real-world problems they encounter in clinics – plus all the content covered in traditional courses.

USC began implementing PBL in 1995, with a six-year pilot program in which the new curriculum ran on a parallel track with the traditional curriculum. For the first five years, a dozen first-year students from each new class participated. In the sixth year, the program was expanded to 24 students. In 2001, the school instituted PBL for its entire first-year class, and the second fully PBL class started last September. (The school will continue its traditional curriculum through 2004, when the last traditional students graduate.)

Problem-based learning is working, says Shuler. He and other dental school faculty compared the national board exam scores of PBL-track students with those of their peers in the traditional track during the six years of the pilot program. The PBL students’ scores have been significantly higher.

“We were comparing groups of students from the same admission class at the same school, but taught using a different pedagogy. No one else has done that,” says Shuler.

Problem-based learning has deep roots in business and engineering schools, and medical schools began experimenting with the method in the 1960s. About two-thirds of American medical schools have since adopted it either partially or fully.

The first dental PBL program was pioneered by Malmö University in Sweden, and others in China, Ireland, Canada, Australia and Great Britain have followed. But in the United States, only Harvard and USC have fully implemented PBL. (Indiana University combines PBL with traditional curricula.)

At USC, clinic patients applaud the new approach. PBL student-dentists work in “verticalized” teams of beginning to advanced clinicians, collaborating and learning together. Patients receive speedier treatment, because more than one person is caring for them. And they have access to more than one student-dentist should they need further consultation.


A PBL team trouble-shoots treatment options in a case, under the supervision of professor Charles Shuler.

Students report an initial struggle coming up to speed with the new method: “When you have had one learning method for 16 to 20 years of your life, it takes some adjustment to do anything differently,” writes Sara Hale, responding to an informal survey of the class of 2005. But the results, students generally agree, are well worth the effort. “When we are presented with a problem, we attack it in a different way than traditionally taught students,” explains Jennifer Politowski. “We think about the various elements involved and make the best decision for the situation, rather than choosing the answer we were given in class.”

Dental school administrators also have a stake in PBL’s success. Within the profession, Shuler points to a need to inspire dentists to be lifelong learners. Under the traditional model, many dentists effectively end their education at graduation. With scientific discoveries and new tools and technologies reshaping the oral health landscape every few years, dental schools must lay the foundation for new generations of family dentists prepared to incorporate dramatic basic-science and clinical-practice advances over the 40 years of their professional lives (the average length of a dentist’s practice).

“We want to prepare students to think into the future and to keep current, so that they are always providing their patients with the highest level of care,” Shuler says.

In Harold Slavkin’s vision of the dental school as a “learning organization,” the learning extends well beyond the 154 acres of the University Park campus. Stepping up the school’s longstanding tradition of community service, USC dental clinics now treat schoolchildren, neighbors, the elderly, homeless and indigent people, veterans and developmentally disabled and medically comprised people – delivering a high level of care in state-of-the-art facilities.

Slavkin considers this a critical part of the school’s mission. He points out that more than 110 million Americans are without any type of dental health insurance, according to a May 2000 report of the Surgeon General. In California, a lack of access to oral health care impacts almost 30 percent of the state’s population, nearly 11 million people – a condition the California Dental Foundation characterized as “a silent epidemic” in a 2001 report.

University-run clinics, Slavkin believes, can make a difference. At USC, all dental students get clinical experience, either at the Norris Dental Science Center (where more than 16,000 patients were treated in 2000-01), or in the school’s many ambulatory clinics and community outreach programs.

Michael Mulvehill is commander-in-chief of this vast enterprise. Giving a tour of the Norris Dental Science Center, the associate dean for clinical affairs buzzes through the halls of the facility, waving to students and faculty who swirl by in a cloud of green and blue smocks.

The second floor, where all pre-doctoral students receive their general dentistry training, sees the most action. In full swing, it can accommodate 154 patients being seen by 154 students at one time. Students quickly learn the drill of checking out sterilized instruments needed for that day’s lesson. The sterilization center decontaminates instruments in an eight-step process, re-packaging them for 18 different procedures – each color-coded so staff and students get exactly what they need.

Beyond the dental school premises, students train under faculty directors across Los Angeles through various outreach programs, including the celebrated USC Mobile Clinic. The 36-year-old program’s wagon train of fully equipped dental units has delivered oral care to more than 75,000 children from low-income families in California and Mexico. Now in the planning stage is an ambitious teledentistry project to make better use of the mobile clinic by allowing USC clinicians to review digital images of prospective patients’ mouths before site visits.

Another program, the Sealant Project, provides preventive care to schoolchildren throughout Southern California. Since it began in 1990, the grant-funded initiative has served more than 4,200 inner-city kids. The youngsters receive oral exams, dental cleanings, dental sealants, fluoride treatments and referrals.

Three years ago, the dental school opened a comprehensive care dental clinic at the Union Rescue Mission in downtown Los Angeles. It has already served more than 2,000 homeless and poor people in the Skid Row/Central Los Angeles area. Its six dental chairs are filled nearly 40 hours a week.

Last year, the dental school added a new van that visits elementary schools in the neighborhoods around USC’s two campuses. In the neighborhood clinic’s first two months of operation, faculty volunteers examined and recommended further treatment for more than 500 children.


At the Norris Dental Science Center, which sees more than 16,000 patients a year, clinical affairs chief Michael Mulvehill confers with two student-dentists.

Through all the school’s community service programs, more than 11,000 people received oral screenings, preventive education and/or treatment during the 2000-01 academic year.

Back in the dental school’s orthodontics clinic waiting room, Jonathan Romero wears a customized retainer, designed by Mah, that gradually draws his no-longer-impacted tooth into its upright position. He will soon be ready for full braces designed to perform double duty: bring his upper and lower teeth into alignment while correcting the original problem.

Mah is pleased with the outcome, given all that could have gone wrong. He credits the Virtual Reality Patient with smoothing the way for a rough procedure.

“With this technology, we’re much more confident about this type of treatment. We can plan better to be more efficient,” he says. “What we’re doing is setting the standard for managing cases of impacted teeth in the future.”

Just what you’d expect of a learning organization, forever changing to meet the next challenge.


Working on Tele-Teeth

In the future, this may be how astronauts get a root-canal. But today’s teledentistry is already bringing expert care to terrestrial dwellers in remote and underserved areas.

High-tech solutions in health care don’t necessarily translate to expensive equipment and treatment, available to only elite populations. USC’s School of Dentistry is already exploring how to use virtual imaging techniques to benefit underserved communities in California.

A multi-phase project, led by plastic surgeon John Meara and dentist James Mah of USC and coordinated by Daniel Plotkin at Childrens Hospital Los Angeles, will put the telecommunications systems in place that allow children to undergo comprehensive dental consultations from remote locations.

“We think this is a great application for virtual reality technologies,” says Mah. “In California, we have a large underserved dental population – areas without dentists or dental specialists of any kind.”

Through teledentistry, a clinic in a remote location could capture digital images via a common digital camera. The clinic could transmit the images to the USC Norris Dental Science Center, where faculty and students could study them. “We may not be able to make a complete diagnosis,” Mah says, “but at least we have a better handle on the problem. We can then begin to allocate needed resources, such as personnel and supplies, make student assignments, and study the necessary procedures.”

Dental school dean Harold Slavkin imagines a day in the not-too-distant future when the mobile clinic student dentists could snap oral pictures of the children of migrant workers and zap those images to USC for real-time consultation with faculty specialists.

“It will happen,” Slavkin says. “We already have the technology. We just need to construct the infrastructure.”

The USC Mobile Clinic, which cared for more than 2,000 children in 23 locations throughout California in 2001, provides a perfect vehicle for USC’s teledentistry program. Because the coach and three trailers – each a self-contained dental office on wheels – travels to the same site only twice a year, teledentistry could significantly maximize the outcome of these visits. USC dentists and their students could examine digital images of patients before the site visit, even make some decisions about treatment before the clinic rolls into town.

Eventually the program might use the Craniofacial Virtual Reality Laboratory’s 3-D imaging technology for orthodontic work and cases involving impacted teeth.

The most obvious application of such 3-D teledentistry would be to design braces.

“The images not only are accurate enough for diagnostic decisions,” Mah says, “but also are dimensionally accurate enough that we can use them to make appliances. We can digitally place brackets and wires on the virtual patients.”

Orthodontists could fabricate the hardware at USC, then send it on to the remote site for fitting on the patient’s teeth.

The teledentistry project is funded, in part, by the Harold McAlister Charitable Foundation and the California Wellness Foundation.

Freelance writer Carol Tucker, MA '84, is a former media representative with the USC News Service.