New Front May Open In War Against Caries
By David G. Jones
Development of an antibody that one day might be used to stop dental caries from forming is being viewed as enticing news.
Full-scale clinical trials to determine the antibody's safety and efficacy will begin soon, casting light on potentially far-reaching implications for the dental profession and for people susceptible to caries formation.
A team of researchers at Guy's Hospital Dental School in London conducted a preliminary clinical trial using the genetically engineered antibody produced by Planet Biotechnology, Inc., a research firm in Mountain View, Calif. Led by Dr. Julian Ma and professor Tom Lehner, the team completed the study in April using a secretory IGA (SIgA) monoclonal antibody named CaroRXJ, produced in genetically altered plants called "plantibodies" designed to prevent infection by the oral bacteria Streptococcus mutans.
The English researchers chose volunteers whose teeth harbored S. mutans. They first decreased the subjects' oral bacterial count, then applied a series of clear and tasteless antibody treatments. According to the researchers, "the bacteria were not able to recolonize the mouth for up to four months following treatment," an effect known as passive immunization.
The preliminary scientific trials were reported in the May issue of Nature Medicine. The trials are being supported in part through Small Business Innovative Research Grants from the National Institute of Dental Research, totaling about $572,000.
And we succeeded in making a secretory IGA antibody by taking genes that encode the antibody and genetically engineering it into a plant," said Elliot L. Fineman, chief executive officer of Planet Biotechnology. "When the plant grows, it produces the antibody, and this is extracted, purified, and is used in the clinical trials."
SIgAs are the antibodies naturally produced by the body to protect oral and other mucosal surfaces against infectious organisms and toxins. The plantibody works by blocking the adherence of the S. mutans bacteria to the teeth.
"Basically, it's just like the principle of a good lawn of grass," said Jim Larrick, MD, PhD, head of research at the Palo Alto Institute of Molecular Medicine, and founder of Planet Biotechnology. "A nice lawn of healthy, growing grass makes it hard for crabgrass to grow. So we reduce all the bacteria in the mouth to very low levels using chlorhexidine mouth wash, and then treat with the antibody. The normal bacterial flora grow back, but the >crabgrass' Streptococcus mutans is unable to recolonize. The antibody blocks the niche where this grows."
The company has received the go-ahead from the Food and Drug Administration to begin full-scale 1/2 (safety/efficacy) clinical trials, which will involve up to 1,000 subjects and are set to begin soon at the University of California, San Francisco, School of Dentistry.
"We're going to try to show both safety and efficacy," Fineman said. "In the work up to now there have been no safety issues and no adverse response in any patients being treated with the antibody."
Fineman said the length of the trial will depend on the accrual rate for patients. He hopes to complete the first phase within 18 months of initiation. If all goes well, the FDA registration trial will begin in a year or so.
If the trials are successful and FDA approves, dentists can expect to see a commercially available product in as little as four years.
We think this product could become part of routine office visits," Fineman said. "Anyone who is of prime cariogenic years, or patients who show a tendency toward caries, would benefit. Patients who have been treated, for example, for head and neck cancer who are at much greater risk for caries would also benefit."
The product would be applied only by a dentist during an office visit. We plan to market our product through dentists, who would apply it to their patients once or twice a year," Larrick said. "The purpose of dentistry is to improve oral health, so this is an ethical product that may have a role in alleviating a lot of pain and suffering."
With the full-scale trials yet to begin, a senior official of the American Dental Association said care must be taken to ensure data from the trials is carefully evaluated before the antibody is declared a success.
"But this work looks very promising, and we're guardedly optimistic about it," said Daniel Meyer, DDS, ADA's associate executive director for its Division of Science. "To us, this is the way the profession should go. Rather than to treat the disease's ravages, it's much better to prevent it from occurring."
While the antibody could eradicate a major cause of caries, it isn't a panacea. "There are other types of bacteria that cause other kinds of decay, such as root caries," said Michael J. Danford, DDS, chair of CDA's Council on Dental Research and Developments. "So this could be a good first step toward helping to eliminate decay."
Bonding With Investments
By Marios P. GregoriouMunicipal bonds are one of the few remaining ways to receive income exempt from regular federal and, in many cases, state income taxes. That is why they are attractive to many investors, especially those in higher tax brackets.
One way for individuals to participate in a portfolio of municipal bonds is through a unit investment trust (UIT). UITs are fixed portfolios of stocks or bonds that are professionally selected, with stated investment objectives. For investors who want an investment that has the potential to reduce taxes and increase spendable income, municipal UITs offer a number of convenient ways to invest in a diversified portfolio of municipal bonds.
Tax-exempt municipal trusts may contain fixed portfolios of quality municipal bonds -- obligations issued by states, cities, counties and other political subdivisions. Those trusts offer tax-exempt interest income and may provide taxable equivalent yields that increase with the owner's tax bracket. National portfolios provide monthly income exempt from regular federal income taxes. Single-state trusts may allow double or even triple income tax exemption for investors residing in their respective states -- an advantage for investors in high-tax states. Insured series trusts appeal to conservative investors seeking a high degree of safety plus tax-exempt income. Portions of the interest income from these types of trusts may be subject to the federal alternative minimum tax.
National Municipal Trusts -- National municipal bond UITs hold bonds issued by states and municipalities to finance schools, highways, hospitals, airports, bridges and other public projects. In most cases, income earned on those units is not subject to regular federal income taxes (although all or a portion may be taxed under state and local laws), making them attractive to taxpayers in the higher tax brackets.
State Municipal Bond Trusts -- State municipal bond UITs work just like national municipal bond UITs, except that their portfolios contain the issues of only one state. Generally, a resident of that state has the advantage of receiving income free from regular federal, state and local income taxes.
Insured Series ITs -- Insured municipal bond trusts contain bonds that are generally rated AAA by Standard & Poor's and offer extra protection through bond insurance. Timely payment of interest and principal on the underlying securities is guaranteed by independent insurance companies. The market value of units of insured trusts is not guaranteed and will fluctuate with changes in market conditions. Unit trusts are sold by prospectus, and terms of the insurance are described in the prospectus.
Municipal trusts have a variety of features. They include:
* Tax-exempt monthly income. While bonds generally pay interest semi-annually, bond UITs provide regular monthly checks. This feature appeals to retired investors and other individuals who prefer a monthly income flow.
* Defined portfolios. Investors in a municipal unit trust are buying a preselected portfolio of bonds. The portfolio is defined so that the securities, maturities, call dates and ratings are all known before you invest.
* Professional selection. Each trusts's portfolio is selected by a team of professional municipal bond analysts and buyers who evaluate a number of factors, including the type of bond and purpose, call features, economic factors, financial position, debt structure, management/governance and various external factors.
* Portfolio supervision. Although the municipal unit investment trust is not managed, analysts generally review and supervise the securities in the portfolio regularly.
* Diversification. Municipal bond portfolios are diversified by issue and bond type to help reduce overall investment risk. To achieve comparable diversification on one's own would require considerable investment capital.
* Low minimum investment. There is a low minimum investment, often as little as $1,000.
* Automatic reinvestment. Investors in municipal trusts may elect to have distributions reinvested at no additional sales charge.
* Daily liquidity. Units may be redeemed at any time. The price received is based on the then-current net asset value of the securities in the portfolio, including a deduction for any remaining deferred sales charge. That is determined by an independent evaluator, based upon the bid price, with no odd-lot penalties. However, depending upon market conditions, the price you receive may be more or less than originally paid.
UITs are available in a variety of maturities to help with various investment objectives, such as to increase current income, reduce taxable income, prepare for retirement, or accumulate a college education fund. Like other investments, unit trusts are subject to market fluctuations and are also sensitive to interest rate changes.
Mr. Gregoriou is an associate vice president for investments for Dean Witter Reynolds Inc. He can be reached at (800) 755-8041. This article does not constitute legal or tax advice. Consult a tax adviser and/or attorney for more information before making tax/legal-related investment decisions.
BC Pill Can Boost Incidence of Dry Socket
Women who use birth control pills are twice as likely to develop dry socket after a tooth extraction, according to a study published recently in the Journal of the Academy of General Dentistry."In general, women have a greater chance than men to develop dry socket," says Vicki Grandinetti, DDS, a Chicago general dentist. "But for women who take oral contraceptives, their likelihood of developing a dry socket is twice as likely because of their increased estrogen levels."
The study reports that women who use oral contraceptives experienced a 31 percent incidence of dry socket after molar extractions performed in the first 22 days after their menstrual cycle. Within two to three days after estrogen use was discontinued, the extraction site tissue began the healing process. For women whose molar extractions were performed on days 23 through 28 of their cycle, no incidence of dry socket occurred.
"Unless there is an emergency, women using birth control should try to schedule their extractions during the last week of their cycle, when estrogen levels are inactive," Grandinetti says. "The healing process can then begin immediately."
Early Intervention and Teamwork Breaks Braces' Grip
Since jaw development slows at about age 13, general practitioners who build good relationships with orthodontists can shorten the time of wearing braces and improve children's chances of maintaining sound dental health, reports the Academy of General Dentistry.Early intervention lets the GP deal with a variety of problems that could cause trouble later. The impact on a child's teeth due to correctable problems such as thumb sucking and tongue thrusting can be reduced or even removed. Dealing with cross bites in the age range of 7 to 11 years can help prevent earaches or headaches later. And early treatment can reduce patients' costs, increase the chance that the GP can perform needed work, and improve the patient's self-image at a younger age.
Children should have an orthodontic screening by age 7, urges the American Association of Orthodontics (AAO). Failure to bring orthodontic care into the picture at an early age could result in a greater need for extraction, a step many practitioners hope to avoid. For maximum results, the AAO encourages clear communication between orthodontists and referring dentists.
Great Expectorations: Saliva-Testing Is Here
Health care professionals soon may shun drawing a patient's blood and instead ask for a sample of spit.Saliva samples not only can detect the onset of periodontal disease and cavities, but also can reveal the presence of AIDS, Alzheimer's, cystic fibrosis, diabetes, hepatitis, ulcers and depression.
Saliva-testing is being hailed as a more convenient method of monitoring the levels of prescription medications, hormones, tobacco, alcohol, steroids, marijuana, cocaine and opiates.
Roughly 99 percent of saliva is water, the remaining one percent is proteins. Also contained in the mixture are varying amounts of serum products and blood cells, bacteria and bacterial products, and bronchial secretions. The electrolytes in the water portion of saliva are believed to cleanse, buffer, and aid in remineralization and alimentary functions.
Saliva's role in lubricating oral tissues and helping food digestion is well-documented. However, current research indicates it may reveal clues about other developments in the body. As a result, dentists and physicians have shown new interest in saliva. By some estimates, half the country's dental schools now incorporate saliva detection into their curricula.
Saliva testing offers many advantages over blood and urine tests: It's easier to collect and store than other body fluids, and saliva collection techniques are far less invasive than collection of blood or urine.
Saliva testing products and kits for home or office have been used in Scandinavian countries for several years, but await approval from the U.S. Food and Drug Administration.
Pain Control Needn't Be a Shock
Although most children can cope with local anesthetic injections, some children fear needles, and giving them injections presents a challenge to the dentist. For other children, the paresthesia that may linger for hours after the completion of the dental procedure may be more objectionable than the injection itself.Researchers at the University of Otago, New Zealand, note that interest has been renewed in the past decade in the applications of electronic pain control in dentistry.
The researchers compared the effectiveness of electronic dental anesthesia (EDA) for pain control during restorative procedures with local anesthetic injection (LA) in 32 children, ages 6 to 12 years. Each child had two antimere primary or permanent molars requiring similar-sized Class I or Class II restorations. Pain levels during restorative treatment were assessed using a visual analogue scale. Behavior and heart rates were also recorded.
The authors point out that the use of transcutaneous electrical nerve stimulation (TENS) to help control chronic pain was introduced in 1967. In the mid-1980s, TENS units were modified for intraoral use. Recently introduced is an EDA device that uses extraoral electrodes, eliminating the inconveniences of intraoral electrodes, such as difficulty in application, obstructed field of operation, and easy detachment.
In the New Zealand study, the antimere teeth were restored in two separate visits with random selection of use of EDA or LA. For the control visits, anesthesia was given by infiltration for the maxillary teeth and inferior nerve block for the mandibular teeth. Cavity preparation began after five minutes. Injections were repeated if the anesthesia was not effective.
After both visits, the children were asked their preferred method of anesthesia and the reasons. Twenty said they preferred EDA to LA. Eleven preferred EDA because there was no need for injection; three liked to control the anesthesia; four liked the feeling with EDA; and one preferred EDA because there was no paresthesia after treatment. Twelve children preferred LA because they found LA more effective for pain control.
The authors report that in their study, six treatment procedures using EDA were interrupted because of insufficient pain control, and treatment was completed using local anesthesia. Four of those children showed high pretreatment anxiety. Two children reported "worst pain" for the cavity preparations even after LA was administered, and one reported "worst pain" for cavity preparation of the antimere molar when LA was used.
Researchers conclude that EDA was less effective than LA in controlling pain during cavity preparation in children age 6 to 12. According to the authors, "This study suggests that the effectiveness of EDA is related to children's dental anxiety, the depth of the restoration, operator attitudes, and whether the teeth are permanent or primary. EDA can be a useful adjunct to providing pain control during restorative dental care in children."
AAHD Elects 1998-99 Officers
The American Association of Hospital Dentists (AAHD) has elected Ronald Mito, DDS, of Los Angeles as president for 1998-99. Mito, an active CDA volunteer, is currently associate dean for Clinical Dental Services at UCLA School of Dentistry. Mito's interests include treatment of medically compromised and phobic patients and postdoctoral general dentistry education. Dr. Paul Glassman of the University of the Pacific School of Dentistry was elected first vice president.
Upcoming Meetings
1998
- Aug. 14-15 Academy of LDS Dentists Conference, Provo, Utah (801) 378-4851
- Sept. 11-13 Oral Health 2000 Consortium, San Diego (312) 836-9900
- Sept. 13-16 American Academy of Periodontology's Annual Meeting, Boston (312) 573-3210
- Sept. 16-19 American College of Prosthodontists Annual Session, San Diego (800) 378-1260
- Oct. 1-3 Annual Scientific Session of the Academy of Surgical Research, Nashville, Tenn. (612) 927-6707
- Oct. 1-3 Third International Congress on Dental Law and Ethics, London, England (44) (0) 171-935-0875
- Oct. 2-3 Society for Advanced Dentistry Inaugural Meeting, New Orleans (317) 290-2613
- Oct. 8-12 World Dental Congress, Barcelona, Spain +44 171 935 7852
- Oct. 8-10 American Society for Dental Aesthetics International Conference on Aesthetic Dentistry, Chicago, (800) 454-2732
- Oct. 24-28 ADA Annual Session, San Francisco (312) 440-2500
- Oct. 31-Nov. 3 Pacific Coast Society of Orthodontists Annual Session, Palm Springs, Calif. (415)441-2410
- Nov. 19-21 International Dental Showcase, NEC Birmingham, U.K. 01722 335599
- Oct. 8-10 American Society for Dental Aesthetics International Conference on Aesthetic
- Feb. 3-6 Academy of Laser Dentistry's Sixth Annual Conference and Exhibition, Palm Springs, Calif. (248) 548-7171
- Feb. 11-13 East Coast District Dental Society Miami Winter Meeting and Dental Expo, (800) 344-5860 or (305) 667-3647
- April 8-11 CDA Scientific Session, Anaheim (916) 443-3382, Ext. 4470
- April 13-17 International Dental Show, Cologne, Germany, http://www.koelnmesse.de/ids
- Aug. 20-22 CDA Scientific Session, San Francisco (916) 443-3382, Ext. 4470
- Sept. 17-18 Society for Advanced Dentistry Annual Meeting, New Orleans (317) 290-2613
To have a meeting included on this list, please send the information to Upcoming Meetings, CDA Journal, P.O. Box 13749, Sacramento, CA 95853 or fax the information to (916) 443-3382.
