Computer-aided design and manufacturing are changing restorative dental treatments, but growing new teeth with stem cells will be the much-sought answer to decay and neglect.
By JUDY SIEGEL-ITZKOVICHPROF. YAEL HOURI-HADDAD in front of a (TNS) the school’s exhibit of a century old dental offices(photo credit: JUDY SIEGEL-ITZKOVICH)
Prof. Yael Houri-Haddad – chairman of oral rehabilitation at the Hebrew University-Hadassah School of Dental Medicine – usually opens her first class with students by mentioning the sad story of George Washington. The first president of the US, who suffered from poor dental health already in his 20s, had only one of his own teeth when he took office. His dentist carved ivory dentures out of hippopotamus ivory and connected them all with brass screws and gold wire springs.Contrary to myths, Washington’s dentures were not made of wood. Yet he suffered terribly, and virtually all his portraits show him looking dour. But, says Houri-Haddad, that was not the first famous case of false teeth; Byzantine-era skulls with ivory teeth stuck in jawbones have been found in archeological digs. After World War I, most false teeth were made of gold, followed by nickel/titanium after World War II, but these were very expensive.Since then, man has searched for the most comfortable, cheapest and longest-lasting dentures – but eventually, she suggests, the problem will be solved by turning stem cells from people’s own teeth into new ones than can be implanted into the jaw.Houri-Haddad, who was promoted to professor a few months ago, runs the largest department in Jerusalem’s dental school – one of only two faculties for dental medicine, with the smaller and younger one at Tel Aviv University.Houri-Haddad, who was born in Tunis to a religious family and was brought by her parents to Israel at the age of 14, wanted to be a physician from adolescence. She actually did her national service (in lieu of Israel Defense Forces service) in an orthopedics center. But even before she was married, she realized that if she wanted a family, it would be too difficult if she were an MD, so she decided to go into dentistry. Now, 31 years later, she is married and has four children, and has never regretted her decision.“I wanted an academic career, teaching and working on patients in the clinic, and that’s what I got,” she says.She spent the years between 1989 and 2000 on her studies at the Jerusalem dental school, earning in addition to her basic DMD degree a PhD and specialty in prosthodontic dentistry. When the department’s chairman, Prof. Erwin Weiss, left to head TAU’s dentistry faculty, Houri-Haddad was named acting head of the department of maxillofacial rehabilitation.“When I began my studies, half of the students were men,” she says, while today 80 percent of dental students are women.In medicine, the percentage of female students is “only” a little over half today. But while she is glad to see other women join her, she adds that “professions in which there is a significant majority of one gender – especially women – means unfortunately that the pay and status decline. I hope the trend will change.”ALTHOUGH MOST people believe it costs the country more to produce a physician than a dentist, they are wrong. The cost of teaching a dental student is NIS 200,000 per year, and the course of study is six years – twice the cost of teaching a physician during the same period (dentists do not need to do an extra year as “stage,” unlike MDs who must do a year’s internship in a hospital).
As a dental, medical and any other type of student (including philosophy, history or engineering) pays only around NIS 12,000 in annual tuition, the extra cost is covered by the Council for Higher Education’s Committee for Planning and Budgeting.Thus the number of dental and medical students is strictly limited by the government according to how much Treasury funding the committee has to spend, even if the need for graduates is significantly beyond the quota.Dental studies are so much more expensive, says Houri-Haddad, because professors and lecturers usually have to teach one-onone, and the cost of equipment – including humanoid oral robots and dental materials – is exorbitant. “Medical school professors can make the rounds with a number of medical students following them to see patients, but this can’t be done with dental treatment,” she explains.The rate of licensed dentists – along with physicians, nurses and pharmacist assistants – continued to decline in 2013, according to the Health Ministry’s 2013 report on personnel in the health professions released a few weeks ago. However, the report said the rate of psychologists, pharmacists, medical lab workers, dental hygienists, optometrists, physical therapists, dieticians, occupational therapists and communications clinicians has increased.The rate of working dentists is 0.68 per 1,000 in 2012 – similar to the OECD average but much lower than it used to be because many who came on aliya from the former Soviet Union are retiring. The rate of local dental school graduates was lower here than the OECD average – largely because of many graduates in Arab and Eastern European countries. The rate of dental graduates from the two local (Israeli) dental schools is low (0.77 per 100,000) compared to the OECD average (2.45).There have been two “policy disasters” in Israel’s dental field in recent years, according to Houri-Haddad. One is the “inexplicable” decision by recently resigned health minister MK Yael German to prohibit fluoridation of Israel’s drinking water.“Fluoride has been proven for many years as significantly bringing down the number of dental caries [cavities], especially in children.In the Scandinavian countries, some dental schools have even been closed down because fluoridation has made tooth decay more rare. German’s decision will cause harm; I hope it will be canceled when a new health minister comes in,” she said, adding however that “there are places around the world with excess natural fluoride, and this can cause harm, so fluoride levels must be controlled.”As for the other damaging policy, she names the program initiated by then-deputy health minister (United Torah Judaism) MK Ya’acov Litzman to provide basic dental care to children. The cheap remuneration per child, says Houri-Haddad, induces many health fund dentists to “over-treat” so they can charge extra for dental care not included in the basic basket. As private pediatric dental specialists were kept out of the program because they are more expensive, some have gone out of business, she continues. In addition, she says, Litzman did not allow researchers at either of the dental schools to conduct objective research and find out if the program was successful in improving children’s dental health, even though such a study was offered by the Jerusalem dental school.“Litzman worried only about getting credit from his own sector of ultra-Orthodox Jews, but it did not necessarily serve them as it should. There could be better ways to spend the tens of millions of shekels each year,” she adds.The dental professor is also worried about the financial and managerial imbroglio at the Hadassah Medical Organization, which includes the dental school.“I have always regarded Hadassah as home, so it has been painful to watch.I hope HMO will received a permanent director-general. We want to restore the shine of HMO, but it will take time.”Another problem in the dental medicine world is that the US Food and Drug Administration has decided to halt the use of amalgam by 2017 and to replace such fillings with composite material. “Companies are developing materials that will be longer lasting without amalgam.”THERE IS, however, exciting news in dentistry – advanced new materials that are safer, longer-lasting and easier to use, and the use of computer-aided technology to design and manufacture crowns, bridges, implants, veneers and other ways of improving less-than-healthy bites.CAD-CAM technology has been used for about a decade, but in the past year or so has really taken off, notes Houri-Haddad.Typically CAD/CAM dental restorations are milled from solid blocks of ceramic or composite resin that closely match the basic shade of the restored tooth. Metal alloys may also be milled or digitally produced.After decayed or broken areas of the tooth are corrected by the dentist, a scan is taken of the prepared tooth and adjacent ones.This image, called a digital impression, is entered into a computer. Software then creates a replacement part, creating a virtual restoration. The software sends this data to a milling machine, where the replacement part is carved out of a solid block of ceramic or composite resin. Stains and glazes are fired to the surfaces of the milled ceramic crown or bridge to correct the otherwise monochromatic appearance of the restoration.The restoration is then adjusted in the patient’s mouth and cemented or bonded in place.Her rehabilitation department has 100 dentists, most of them paid staffers but some volunteers. The HMO budget cuts threatened to lead to significant dismissals, she said, but “we protected the staff, and there were few cuts.” But there is hope for expansion in the dental school, now that the Israel Defense Forces has decided to start a dental student program called Binah (“wisdom”) along the lines of HMO’s military medicine track (called Tzameret) to teach medical students to become military physicians, the dental school will need more staffers. “Today we have about 60 students at the sixth year but at the first and second years we have about 75 students including Binah,” says Houri-Haddad.Instead of conventional X-rays and physical impressions to plan the size, placement and angle of implants, crowns, bridges and other tooth replacements, new technologies will increasingly offer computerized, 3D imaging using a camera.“These are not less expensive, but there are better results, and they last longer.”The first company to get involved was Cerek in Germany, but now there are many more whose products are similar.“There is still a problem of dealing with places under the gums, but there is a startup in Tel Aviv said to have developed technology that can overcome this problem,” she says. “Computer engineers work closely with dentists to bring about these innovations.The new computerized technologies make very good clinical and teaching tools.”Houri-Haddad conducts research on tissue cultures and mice, but others work on guinea pigs, dogs – especially beagles – and pigs. She specializes in the genetics of periodontal disease.“It was thought that dentures that are removed and put in a glass of water at night, or left in the mouth (they are unscrewed for cleaning from time to time and then returned) would be replaced by implants that suit the population better because they live decades longer than they did in 1900. But not everybody can afford or wants implants – whose cost can reach NIS 100,000 for a whole mouth – so we will teach about dentures for a long time in the future,” she says.Dentists have to learn a lot about chronic disease from cardiovascular problems to genetic disorders, osteoporosis, multiple sclerosis and diabetes, as well as the impact of radiotherapy and chemotherapy for cancer, as these can have an impact on the production of saliva, nerves and blood vessels in the mouth. In addition, treatment of chronic tobacco smokers is difficult and less successful.WITH DENTAL school teaching so expensive, the Jerusalem school is hoping it can boost its income by making known its clinic, in which advanced students treat patients under the close supervision of their teachers.“The cost is relatively low – NIS 60 for filling a cavity and NIS 800 for a crown. We use the best dental labs. In my department, we have three clinics and 19 dental chairs. They work only in the morning, but if we had a second shift, we could accommodate many more.”Large numbers of Jerusalem- area residents don’t know about this service.“We don’t have enough customers, partly because the HMO financial crisis made potential patients think the service wasn’t available and also due to the fact that we didn’t advertise. “Thanks to the students’ skills and the faculty’s supervision, there have been very few problems.”The dental school has an advanced general practitioner program for its dental students, allowing those who finished sixth year of studies to spend a day per week treating patients and another day teaching dental students in the lower classes.The Hadassah Academic College, for years a sister institution of HMO, used to teach dental technicians, but it was discontinued.“CAD/CAM, which is a type of 3D printing system, will not eliminate such work. But now, instead of dental technicians working on their own, there are large companies that produce crowns and others, with the coloring and engraving.Some Israeli dentists even send 3D images to China, which returns crowns, bridges and others within a week, but it is more cumbersome that having them nearby, because sometimes they have to be sent back for changes to be made,” said the department head. “The quality can be OK; this arrangement has been bringing down prices around the world.”But what dental rehabilitation specialists are really looking to as the future is “teeth from the test tube to the mouth. It will be a process of removing a patient’s own stem cells that would take weeks to grow into full-sized teeth. But careful precautions must be taken, because stem cells have the potential of leading to excessive growth and cancer,” concludes Houri-Haddad.“This technology is still experimental and very immature. But this is the future.”
