Primary Teeth Found a Source of Stem Cells

Scientists report for the first time that primary teeth contain a rich supply of stem cells in their dental pulp. Researchers say this unexpected discovery could have important implications because the stem cells remain alive inside the tooth for a short time after it falls out of a child’s mouth, suggesting that the cells could be readily harvested for research.

According to the scientists, who published their findings online in the Proceedings of the National Academy of Sciences, the stem cells are unique compared to many “adult” stem cells in the body. They are long-lived, grow rapidly in culture, and, with careful prompting in the laboratory, have the potential to induce the formation of specialized dentin, bone, and neuronal cells. If follow-up studies extend these initial findings, the scientists speculate they may have identified an important and easily accessible source of stem cells that possibly could be manipulated to repair damaged teeth, induce the regeneration of bone, and treat neural injury or disease.

“Doctors have successfully harvested stem cells from umbilical cord blood for years,” said Songtao Shi, DDS, PhD, a scientist at the National Institute of Dental and Craniofacial Research and the senior author on the paper. “Our finding is similar in some ways, in that the stem cells in the tooth are likely latent remnants of an early developmental process.”

Shi and colleagues named the cells SHED, which stands for stem cells from human exfoliated deciduous teeth. Shi said the acronym was needed to differentiate SHED from stem cells in adult tissues, such as bone or brain. “Stem cell research has exploded during the past seven or eight years, yet people still talk in general terms of postnatal and adult stem cells as though they are one and the same. Postnatal cells from children may act totally differently than adult stem cells, and we felt the inherent difference needed to be emphasized,” Shi said.

The new finding stems from a chance interaction. As Shi recounts, it happened one evening when his then 6-year-old daughter, Julia, asked for help in pulling out a loose primary tooth. “Once it was out, we sat and looked carefully at the tooth,” recalled Shi, a pediatric dentist. “I said, ‘Wait a minute, there is some red-colored tissue inside of the tooth,’ so I took the tooth to my laboratory the next day and examined it. Sure enough, it had beautiful pulp tissue left over.”

A few days later, when another of Julia’s teeth came out, Shi said he was better prepared. He placed the tooth into a liquid medium used to culture cells, drove it to the laboratory, and extracted the dental pulp. Soon thereafter, he succeeded in isolating living stem cells from the tissue, a discovery that would lead to the collection of more exfoliated teeth from Julia and other children.

The group launched an initial round of studies to determine whether the cells would grow well in culture. Using dental pulp extracted from the children’s exfoliated incisors, they discovered that about 12 to 20 stem cells from each tooth reproducibly had the ability to colonize and grow in culture.

“We also found the SHED behaved much differently than dental pulp stem cells from permanent teeth, which our group studied previously,” said Masako Miura, MD, PhD, an NIDCR scientist and a lead author on the study. “They exhibited an ability to grow much faster and doubled their populations in culture at a greater rate, suggesting SHED may be in a more immature state than adult stem cells.”

Muria said she and her colleagues soon found these cells could be prompted to express proteins on their surface indicative of stem cells that were in the process of switching into bone and dental pulp cells. This discovery led to additional follow-up experiments, led by Bai Lu, PhD, of the National Institute of Child Health and Human Development, to determine whether SHED also possessed the potential to switch into neural and fat cells. The groups found, under specific cell culture conditions, that the cells responded accordingly, expressing a variety of proteins indicative of neural and fat cells.

“These data are just the start,” Shi said. “We’re trying to characterize more fully which cell types can be generated from these stem cells. Can they be switched into nerve cells only? We need to find this out. We’re also interested in determining the difference between adult dental pulp stem cells and those in deciduous teeth.”

Human Genome Mapping Completed -- Two Years Early

The International Human Genome Sequencing Consortium, led in the United States by the National Human Genome Research Institute and the Department of Energy, has announced the successful completion of the Human Genome Project more than two years ahead of schedule.

The research institute also unveiled its bold new vision for the future of genome research, officially ushering in the era of the genome. The vision was published in the April 24 issue of the journal Nature, coinciding with the 50th anniversary of Nature’s publication of the landmark paper that described DNA’s double helix.

The international effort to sequence the 3 billion DNA letters in the human genome is considered by many to be one of the most ambitious scientific undertakings of all time.

“The Human Genome Project has been an amazing adventure into ourselves, to understand our own DNA instruction book, the shared inheritance of all humankind," said Genome Research Institute Director Francis S. Collins, MD, PhD, leader of the Human Genome Project. “All of the project’s goals have been completed successfully -- well in advance of the original deadline and for a cost substantially less than the original estimates.”

Aristides Patrinos, PhD, director of the Department of Energy’s Office of Biological and Environmental Research in the Office of Science, said, “Sequencing the human genome was a pioneering venture with risks and uncertainties. But its success has created a revolution -- transforming biological science far beyond what we could imagine. We have opened the door into a vast and complex new biological landscape. Exploring it will require even more creative thinking and new generations of technologies.”

The flagship effort of the Human Genome Project has been producing the reference sequence of the human genome. The international consortium announced the first draft of the human sequence in June 2000. Since then, researchers have worked tirelessly to convert the “draft” sequence into a “finished” sequence.

The finished sequence produced by the Human Genome Project covers about 99 percent of the human genome’s gene-containing regions, and it has been sequenced to an accuracy of 99.99 percent. The sequence data generated by the Human Genome Project has been swiftly deposited into public databases and made freely available to scientists around the world, with no restrictions on its use or redistribution.

To spur the acceleration of medical research, the Genome Research Institute’s “A Vision for the Future of Genomics Research” sets forth a series of challenges intended to energize the scientific community in using the newfound understanding of the genome to uncover the causes of disease and to develop bold new approaches to the prevention and treatment of disease. The plan was the outcome of more than a year of intense discussions with nearly 600 scientific and public leaders from government, academia, nonprofit organizations and the private sector.

Many of the challenges in the vision are aimed at utilizing genome research to combat disease and improve human health. The recommendations include calls for researchers to work toward:

* New tools to allow discovery in the near future of the hereditary contributions to common diseases, such as diabetes, heart disease and mental illness;

* New methods for the early detection of disease;

* New technologies that can sequence the entire genome of any person for less than $1,000; and

* Wider access to tools and technologies of “chemical genomics” to improve the understanding of biological pathways and accelerate drug discovery.

Additional information can be found at www.genome.gov.

Correction

Morris S. Clark, DDS, was inadvertently left off as a co-author with Stanley F. Malamed, DDS, of "Nitrous Oxide-Oxygen: A New Look at a Very Old Technique," which appeared on Page 397 of the May 2003 issue of the Journal of the California Dental Association.

Our apologies to Dr. Clark.

Nearly a Million Children Were Abused in 2001

An estimated 903,000 children across the country were victims of abuse or neglect in 2001, according to national data released by the Department of Health and Human Services. The statistics indicate that about 12.4 out of every 1,000 children were victims of abuse or neglect, a rate comparable to the previous year’s rate of 12.2 out of 1,000 children.

“A nation as compassionate as ours should ensure that no child is a victim of abuse or neglect. The number of children that are being abused and neglected in this country is an unacceptable daily tragedy,” Health and Human Services Secretary Tommy G. Thompson said. “We must do more to protect our most vulnerable children.”

As part of Health and Human Services’ 2004 budget request, the Bush administration is proposing a new approach to protecting children in the child welfare system. Under the plan, states and tribes would have the option of using some money now designated solely for foster care to support a range of abuse-preventive services and programs. The proposal provides the flexibility and sustained financial support necessary to build programs for children and families aimed at preventing maltreatment and removal from home.

The data are based on information collected through the National Child Abuse and Neglect Data System. The data show that child protective service agencies received about 2,672,000 reports of possible maltreatment in 2001. There were 903,000 substantiated cases of maltreatment of children -- the majority of which involved cases of neglect. About 1,300 children died of abuse or neglect, a rate of 1.81 children per 100,000 children in the population.

The full report, “Child Maltreatment 2001,” is available at www.calib.com/nccanch/prevmnth. A table of state and national child abuse and neglect victimization rates for 2000 and 2001 is available from the National Clearinghouse on Child Abuse and Neglect at (800) 394-3366 or by e-mail at nccanch@calib.com.

California Dental Board Approves OSAP for C.E.

The Dental Board of California has named the nonprofit Organization for Safety and Asepsis Procedures a registered continuing education provider. California residents who attend OSAP programs or complete OSAP C.E. exams can now earn credit hours that are approved through the state. The approval is granted through February 2005.

“We are so pleased to have our educational program and materials approved for C.E. credit in California,” said OSAP executive director Therese Long, CAE. “California dental workers have been so loyal to OSAP; in addition to receiving top-notch infection control and safety information, they can also receive credit toward maintaining their licenses and certifications.”

Information on OSAP conferences, newsletters, training programs, and other C.E. offerings is available at www.osap.org.

Oral Piercing: Patients Need the Hole Story

In addition to acting as an advocate for safe piercing, the dental profession also must inform patients about the risks involved with oral piercing, so that patients can make informed choices, wrote Jay T. Biber, DMD, in the January-February Northwest Dentistry, journal of the Minnesota Dental Association.

Biber noted that people considering oral piercing, as well as many parents, are increasingly seeking input from their dentists. The documented detrimental effects of oral piercings on some individuals’ oral health make it difficult for dentists to condone these procedures, Biber said.

The risks should be presented in a factual, nonjudgmental manner so as not to close doors to patients who later might need assistance with complications arising from their piercings.

Biber said the most common oral piercing site is a vertical piercing through the midline of the tongue, anterior to the lingual frenum. The tongue may also be pierced multiple times, off-center or horizontally. These alternative sites increase the risk of nerve damage or hemorrhage.

The lip is the second most frequently pierced oral site, generally in the midline, but also sometimes off-center, Biber said. The cheeks and lingual or maxillary frenum are increasingly popular piercing sites.

Biber noted that a variety of complications resulting from oral piercings have been documented, including tissue hyperplasia, swelling and dysphagia, hypotensive collapse, tetanus, Ludwig’s angina, hepatitis transmission, and bacterial endocarditis.

“Peer-piercing” is becoming increasingly popular, Biber noted; and this increases the risk of young people acquiring infectious diseases through inadequate sterilization, reusing of instruments, or sharing of oral jewelry.

Biber said that complications appear to occur relatively infrequently. However, the potential for serious medical consequences resulting from oral piercings has been documented and should be included as part of the process of informed consent prior to an oral piercing.

Sleepy Dental Patient May Be Clue to Health Problem

Patients who fall asleep in the dental chair may be presenting dentists with vital clues as to their health, wrote Leslie C. Dort, DDS, in the January 2003 Journal of the Canadian Dental Association.

Armed with knowledge of excessive daytime sleepiness, dentists can play a role in guiding patients toward crucial treatment. Excessive daytime sleepiness can be a symptom of several underlying disorders, Dort said. Recognizing the problem and referring patients for diagnosis can be lifesaving.

Sleepiness occurs in 5 percent to 13 percent of the general population, according to Dort. Falling asleep in the dentist’s office may be a sign of excessive daytime sleepiness, he noted. Common causes are:

* Insufficient sleep syndrome or sleep deprivation;

* Sleep apnea syndrome (including upper airway resistance syndrome);

* Sedating medications;

* Withdrawal from stimulants;

* Narcolepsy;

* Psychiatric disorders;

* Idiopathic hypersomnia; and

* Periodic limb movement disorder.

According to Dort, dentists should be concerned about sleepy patients who may be a danger to themselves and others. A few moments of careful consultation could enable dentists to direct patients with excessive sleepiness toward treatment that might improve quality of life, decrease cardiovascular morbidity, and ultimately save lives, Dort said.

Although dentists are not trained to diagnose sleep disorders, Dort said, they are in a unique position as health professionals to recognize patients who suffer from a sleep disorder.

Pay Attention to Patients’ Tobacco Use to Avoid Malpractice Claims

Substantial evidence exists that smoking can contribute to periodontal disease and bone loss, particularly during orthodontic treatment, wrote Elizabeth Franklin in the January/February 2003 issue of the Bulletin, publication of the American Association of Orthodontists.

The development or exacerbation of periodontal disease during orthodontic treatment is one of the most costly causes of loss in orthodontic malpractice cases, Franklin wrote. Consequently, several risk-management issues should be considered when treating patients who smoke or use tobacco products.

Franklin noted that dentists should first ask patients if they smoke or use tobacco products. Medical and dental history forms should also include questions about these habits.

If adult patients confirm they use tobacco products, Franklin said, they should be encouraged to quit. She suggested that dentists may also consider declining to treat these patients if it is determined that the tobacco use will result in a poor outcome.

For dentists who decide to treat smokers for orthodontics, Franklin recommended steps to protect against allegations of exacerbation of periodontal disease or the development of bone loss. Dentists should:

* Take excellent beginning records, including X-rays and photos;

* Learn as much as possible from the patient about prior periodontal problems and treatment;

* Make sure adult patients have a periodontal evaluation and discuss with them their ability to undergo orthodontic treatment;

* Have a thorough informed consent discussion with the patient and place a signed document in the patient’s record;

* Take interim X-rays to clarify the health of bone structure as treatment progresses;

* Keep a close eye on the condition of the gingival tissue for signs of inflammation and other problems, and refer the patient when appropriate;

* Ask the patient about abnormal pain and continually check for abnormal mobility;

* Be sure the patient maintains a vigilant oral hygiene routine; and

* Consider the possibility of early termination of treatment at the first opportunity once a problem presents itself, not allowing the disease to exacerbate.

Franklin advised dentists to clearly document patient records regarding all these issues. This documentation, she said, can be used as a defense in any claims-handling process.

Honors

Kenneth Frangadakis, DDS, of Cupertino, Calif.; Larry Loos, DDS, MA, of Greenbrae, Calif.; and Clifford Ruddle, DDS, of Santa Barbara, Calif., are the 2003 recipients of the Medallion of Distinction Award from the University of the Pacific School of Dentistry. Presented annually by Dean Arthur A. Dugoni, DDS, the prestigious medallion is the highest honor bestowed by the organization and recognizes individuals who have made outstanding contributions to the School of Dentistry, research, dental education, or the community. (photos)

Richard K. Rounsavelle, DDS, of Torrance, Calif., has been elected vice president of the Academy of Osseointegration.

Paul Glassman, DDS, MA, MBA, has been re-elected president of Special Care Dentistry. Special Care Dentistry is an international organization of oral health professionals and other individuals devoted to promoting oral health and well-being for people with special needs.

Upcoming Meetings

2003

June 6-8 Academy of Dental Sleep Medicine 12th Annual Meeting, Chicago, (708) 273-9335, www.dentalsleepmed.org.

June 13-14 38th Annual Allyn D. Burke Dental Symposium, Naval Postgraduate School, Monterey, Calif., (831) 394-2435.

June 19-22 OSAP 2003 Symposium, Tucson, Ariz., 800-298-OSAP.

July 17-20 Academy of General Dentistry Annual Meeting, Nashville, (888) AGD-DENT, www.agd.org.

Oct. 23-26, ADA Annual Session, San Francisco, (800) 232-1432.

Nov. 2-7 U.S. Dental Tennis Association Annual Meeting, Palm Desert, Calif., (800) 445-2524.

Nov. 8-9 International Conference on Evidence-Based Dentistry, Chicago, j.ryley@elsevier.com

Dec. 5-7 California Academy of General Dentistry Annual Meeting, San Diego, (877) 408-0738, www.cagd.org.

2004

March 3-6 Academy of Laser Dentistry 11th Annual Conference, Palm Springs, Calif., (954) 346-3776, www.laserdentistry.org.

April 15-18 CDA Spring Scientific Session, Anaheim, (916) 443-3382, Ext., 4470.

Sept. 8-11 International Federation of Endodontic Associations Sixth Endodontic World Congress, Brisbane, Queensland, Australia, www.ifea2004.im.com.au.

Sept. 10-12 CDA Fall Scientific Session, San Francisco, (916) 443-3382, Ext. 4470.

Sept. 30-Oct. 3 ADA Annual Session, Orlando, Fla., (312) 440-2500.

To have an event included on this list of nonprofit association meetings, please send the information to Upcoming Meetings, CDA Journal, P.O. Box 13749, Sacramento, CA 95853 or fax the information to (916) 443-2943.