Friday, July 31, 2009

FDA Dental Mercury Report

Mercury Released By Dental Amalgam Fillings Are Not High Enough To Cause Harm, FDA Finds

The U.S. Food and Drug Administration today issued a final regulation classifying dental amalgam and its component parts – elemental mercury and a powder alloy—used in dental fillings. While elemental mercury has been associated with adverse health effects at high exposures, the levels released by dental amalgam fillings are not high enough to cause harm in patients.

The regulation classifies dental amalgam into Class II (moderate risk). By classifying a device into Class II, the FDA can impose special controls (in addition to general controls such as good manufacturing practices that apply to all medical devices regardless of risk) to provide reasonable assurance of the safety and effectiveness of the device.

The special controls that the FDA is imposing on dental amalgam are contained in a guidance document that contains, among other things, recommendations on performance testing, device composition, and labeling statements.

Specifically, the FDA recommended that the product labeling include:

* A warning against the use of dental amalgam in patients with mercury allergy;
* A warning that dental professionals use adequate ventilation when handling dental amalgam;
* A statement discussing the scientific evidence on the benefits and risk of dental amalgam, including the risks of inhaled mercury vapor. The statement will help dentists and patients make informed decisions about the use of dental amalgam.

Dental amalgam is a “pre-amendment device,” which means that it was in use prior to May 28, 1976, when the FDA was given broad authority to regulate medical devices. That law required the FDA to issue regulations classifying pre-amendment devices according to their risk into class I, II, or III. Although the FDA previously had classified the two separate parts of amalgam – elemental mercury and the metal powder alloy – it had not issued a separate regulation classifying the combination of the two, dental amalgam. During this time, however, dental amalgam has been subject to all applicable provisions of the law.

Today’s regulation also reclassifies the mercury component of dental amalgam from Class I (low risk) to Class II (moderate risk).

Over the past six years, the FDA has taken several steps to assure that the classification of dental amalgam is supported by strong science.

In 2002, the agency issued a proposed rule to classify dental amalgam and identify any special controls necessary for its safe and effective use.

Due to a high number of comments on that rule, the agency held an advisory committee meeting in 2006, inviting dental and neurology experts to review existing scientific data on dental amalgam, especially with regard to its toxicity in pregnant women and children.

The agency drafted a review of recent and relevant peer-reviewed scientific literature on exposure to dental amalgam mercury. The advisory committee asked that the agency conduct an even deeper review of the scientific literature on this topic. In all, the agency considered some 200 scientific studies.

On April 28, 2008, the FDA reopened the comment period on the 2002 proposed classification in order to elicit the most up-to-date comments and information related to classification of dental amalgam. Today’s rule reflects the years of agency review on this topic.

FDA’s Web site on dental amalgam.

Wednesday, July 29, 2009

Worm-like Structures Inside Dissected Molar



Micro-images Of Strange, Worm-like Structures Uncovered Inside Dissected Molar



New, micro-images of strange, worm-like structures uncovered inside a dissected molar might have been held in ancient times as proof that gnawing tooth worms were the cause of tooth decay, a theory widely believed in many cultures before modern times.

The structures are not worms, but what they are is still in question.

Studies by University of Maryland Dental School researchers’ presented today at the annual meeting of the Microscopy Society of America in Richmond revealed cylindrical objects extending or ‘growing’ out of the natural pores or tubules of teeth. Inside a human tooth, more than 50,000 such tubules per square millimeter act as channels running from the nerve up through the tooth. They are associated with transporting hot or cold sensitivity to the tooth nerve. [A human hair by comparison is 40 micrometers wide.]

For years, scientists have debated the exact nature of the worm-like structures, which were photographed in clear detail by Ru-Ching Hsia, director of the electron microscope core facility at the School.

Dentists’ explanations vary on nature and origin of the structures. “Most say ‘I have no idea.’ Others say they are made of bacteria, or minerals, or hyphal branches of yeast cells (C. albicans) which have infected the tooth structure, or perhaps they are a cellular process of the dentinal tubules,” said co-presenter Gary Hack, DDS, associate professor in the Dental School. For the sake of humoring his students, Hack says, “I call them tooth worms and I’m sticking to it.”

The aim of the Maryland study was to investigate the structures with scanning electron imagery and different specimen preparation techniques. The researchers’ observations raised new questions in the controversy over nature of the strange structures. For example, they found two of the cylinder structures within a single tubule, a discovery that challenges the hypothesis that the structures are cellular extensions.

The tubules ranged from 2.6 to 3.5 micrometers in diameter and the worm-like structures were smaller in the tubules in which they appeared. The structures were as long as 9 micrometers, extending out of the tubule opening. Whereas the majority of the structures appear to be hollow and devoid of any content, a number of these structures appear to be solid. The majority of the structures have a diameter ranging from 1.5 to 1.9 micrometers. Some of the structures appeared to be solid. Other pictures revealed a comparatively thin, hollow structure emerging from a single dentinal tubule.

Across the ages, both advanced civilizations and as far back as the Roman Empire and the Middle Ages believed in the tooth worm, with physicians prescribing various herbs, rinsings and fumigations.

Tuesday, July 14, 2009

Oral health care within health care reform

For largely historical reasons, the dental profession has evolved parallel to, but separately from, the medical profession. Medicine and dentistry have different educational, health care delivery and payment systems. But the mouth and body are not separate biologic systems. Recent dental research findings are uncovering the full extent to which oral health is linked to general health.

The two most common dental diseases, dental caries (tooth decay) and periodontal disease (gum disease) are the sequelae of microbial infections. Yet, for the more than 80 million American who have medical insurance, but no dental insurance, that infection is not covered. Further, periodontal infections result in a full body inflammatory response that may explain the association with other systemic diseases of inflammatory origin, such as cardiovascular disease.

Oral health research is the underpinning for good oral health, and has greatly affected the way oral health care is delivered. However, advances in care and treatment models have not been shared equally by all Americans, and the physical and economic burden of oral disease continues to outweigh that of other more commonly covered diseases and conditions. More than 51 million school hours and 164 million hours of work are lost each year due to dental related absences. While continued dental research is essential to managing and one day eliminating oral disease, putting current knowledge into practice now is critical to improving oral health for all Americans.

In 2000, the U.S. Surgeon General called the nation's attention to the importance of oral health with the landmark report "Oral Health in America." The report recognized the associations between oral health and general health and called upon policy makers to "build an effective health infrastructure that meets the oral health needs of all Americans and integrates oral health effectively into overall health." Nearly a decade later, it's time to respond to the Surgeon General.

The American Association for Dental Research has made the following policy recommendations:

Provide accessible and affordable oral health care to facilitate the application of dental research findings and to improve the oral health of all Americans

As research has shown the interconnectedness between oral health and overall health, include the prevention, diagnosis, and treatment of oral diseases in health care reform.

Continue a sustained investment in biomedical research, including in the NIH National Institute of Dental and Craniofacial Research to further reduce the burden of oral diseases for all Americans.

The entire Statement is available here.

Saturday, July 11, 2009

Diets bad for the teeth are also bad for the body

Beyond the immediate distress, dental pain may portend future medical problems

Dental disease may be a wake-up call that your diet is harming your body.

"The five-alarm fire bell of a tooth ache is difficult to ignore," says Dr. Philippe P. Hujoel, professor of dental public health sciences at the University of Washington (UW) School of Dentistry in Seattle. Beyond the immediate distress, dental pain may portend future medical problems. It may be a warning that the high-glycemic diet that led to dental problems in the short term may, in the long term, lead to potentially serious chronic diseases.

Hujoel reviewed the relationships between diet, dental disease, and chronic systemic illness in a report published July 1 in the Journal of Dental Research. He weighed two contradictory viewpoints on the role of dietary carbohydrates in health and disease. The debate surrounds fermentable carbohydates: foods that turn into simple sugars in the mouth. Fermentable carbohydrates are not just sweets like cookies, doughnuts, cake and candy. They also include bananas and several tropical fruits, sticky fruits like raisins and other dried fruits, and starchy foods like potatoes, refined wheat flour, yams, rice, pasta, pretzels, bread, and corn.

One viewpoint is that certain fermentable carbohydrates are beneficial to general health and that the harmful dental consequences of such a diet should be managed by the tools found in the oral hygiene section of drugstores. A contrasting viewpoint suggests that fermentable carbohydrates are bad for both dental and general health, and that both dental and general health need to be maintained by restricting fermentable carbohydrates.

The differing perspectives on the perceived role of dietary carbohydrates have resulted in opposing approaches to dental disease prevention, Hujoel notes, and have prompted debates in interpreting the link between dental diseases and such systemic diseases as obesity, diabetes, and some forms of cancer.

Over the past twenty years or so, Hujoel says, people have been advised to make fermentable dietary carbohydrates the foundation of their diet. Fats were considered the evil food. A high-carbohydrate diet was assumed to prevent a number of systemic chronic diseases. Unfortunately, such a diet - allegedly good for systemic health - was bad for dental health. As a result, cavities or gingival bleeding from fermentable carbohydrates could be avoided only – and not always successfully, as Hujoel points out -- by conscientious brushing, fluorides, and other types of dental preventive measures. When these measures are not successful, people end up with cavities and gum disease.

Hujoel observed that the dental harms of fermentable carbohydrates have been recognized by what looks like every major health organization. Even those fermentable carbohydrates assumed to be good for systemic health break down into simple sugars in the mouth and promote tooth decay. All fermentable carbohydrates have the potential to induce dental decay, Hujoel notes.

But what if fermentable carbohydrates are also bad for systemic health? Hujoel asks. What if dietary guidelines would start incorporating the slew of clinical trial results suggesting that a diet low in fermentable carbohydrates improves cardiovascular markers of disease and decreases body fat? Such a change in perspective on fermentable carbohydrates, and by extension, on people's diets, could have a significant impact on the dental profession, as a diet higher in fat and protein does not cause dental diseases, he notes. Dentists would no longer be pressed to recommend to patients diets that are bad for teeth or remain mum when it comes to dietary advice. Dentists often have been reluctant, Hujoel says, to challenge the prevailing thinking on nutrition. Advising patients to reduce the amount or frequency of fermentable carbohydrate consumption is difficult when official guidelines suggested the opposite.

The close correlation between the biological mechanisms that cause dental decay and the factors responsible for high average levels of glucose in the blood is intriguing. Hujoel explains that eating sugar or fermentable carbohydrates drops the acidity levels of dental plaque and is considered an initiating cause of dental decay.

"Eating these same foods, he says, is also associated with spikes in blood sugar levels. There is fascinating evidence that suggests that the higher the glycemic level of a food, the more it will drop the acidity of dental plaque, and the higher it will raise blood sugar. So, possibly, dental decay may really be a marker for the chronic high-glycemic diets that lead to both dental decay and chronic systemic diseases. This puts a whole new light on studies that have linked dental diseases to such diverse illnesses as Alzheimer's disease and pancreatic cancer."

The correlations between dental diseases and systemic disease, he adds, provide indirect support for those researchers who have suggested that Alzheimer's disease and pancreatic cancer are due to an abnormal blood glucose metabolism.

The hypotheses on dental diseases as a marker for the diseases of civilization were postulated back in the mid-20th century by two physicians: Thomas Cleave and John Yudkin. Tragically, their work, although supported by epidemiological evidence, became largely forgotten, Hujoel notes. This is unfortunate, he adds, because dental diseases really may be the most noticeable and rapid warning sign to an individual that something is going awry with his or her diet.

"Dental problems from poor dietary habits appear in a few weeks to a few years," Hujoel explains. "Dental improvement can be rapid when habits are corrected. For example, reducing sugar intake can often improve gingivitis scores (a measurement of gum disease) in a couple of weeks. Dental disease reveals very early on that eating habits are putting a person at risk for systemic disease. Because chronic medical disease takes decades to become severe enough to be detected in screening tests, dental diseases may provide plenty of lead-time to change harmful eating habits and thereby decrease the risk of developing the other diseases of civilization."

In planning a daily or weekly menu, Hujoel suggests: "What's good for your oral health looks increasingly likely to also benefit your overall health."

Wednesday, July 8, 2009

Link between obesity and oral bacterial infection?

Forsyth scientists suggest linkages between obesity and oral bacterial infection

A scientific team from The Forsyth Institute has discovered new links between certain oral bacteria and obesity. In a recent study, the researchers demonstrated that the salivary bacterial composition of overweight women differs from non-overweight women. This preliminary work may provide clues to interactions between oral bacteria and the pathology of obesity. This research may help investigators learn new avenues for fighting the obesity epidemic.

This work will be published in the Journal of Dental Research, and is available online today at http://jdr.sagepub.com/cgi/content/full/88/6/519."There has been a world-wide explosion of obesity, with many contributing factors," said Dr. J. Max Goodson, senior author of the study. "However, the inflammatory nature of the disease is also recognized. This led me to question potential unknown contributing causes of obesity. Could it be an epidemic involving an infectious agent?" "It is exciting to image the possibilities if oral bacteria are contributing to some types of obesity," added Goodson.

Summary of Study

In order to measure the salivary bacterial populations of overweight women, samples were collected from 313 women with a body mass index between 27 and 32 (classifying them as overweight). Using DNA analysis, the researchers measured the bacterial populations of this group and compared it with historical data from 232 individuals that were not overweight. Significant differences in seven of the 40 species studied occurred in the salivary bacteria of subjects in the overweight group. In addition, more than 98 percent of the overweight women could be identified by the presence of a single bacterial species, called Selenomanas noxia, at levels greater than 1.05 percent of the total salivary bacteria. These data suggest that the composition of salivary bacteria changes in overweight women. It seems likely that these bacterial species could serve as indicators of a developing overweight condition and possibly be related to the underlying causation.

Dr. Goodson noted that the reasons for a relationship between obesity and oral bacteria are likely complex. The observed relationship may be circumstantial as being related to diet or opportunistic due to metabolic changes. In the next phase of this research, Dr. Goodson plans to further examine this relationship by initially conducting a controlled cohort study to see if this initial observation can be reproduced. In addition, he hopes to conduct longitudinal studies in children to see if oral infection relates to weight gain. Ultimately, the development of strategies to eliminate specific oral bacteria would be required to provide definitive evidence that certain oral bacteria may be responsible for weight gain.

Monday, July 6, 2009

Sugar substitute prevents early-childhood cavities

Children given an oral syrup containing the naturally occurring sweetener xylitol may be less likely to develop decay in their baby teeth, according to a report in the July issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

Early childhood caries (cavities), also called baby bottle tooth decay or nursing caries, continue to increase in prevalence, according to background information in the article. "Poor children experience rates twice as high as those of their more affluent peers, and their disease is more likely to be untreated," the authors write. "Poor oral health affects diet and nutrition and significantly diminishes quality of life. However, tooth decay is a disease that is largely preventable."

Xylitol, approved in the United States for use in food since 1963, has been shown to effectively prevent tooth decay by acting as an antibacterial agent against organisms that cause cavities. These previous investigations have primarily involved chewing gum or lozenges used in school-age children with permanent teeth. Peter Milgrom, D.D.S., of the University of Washington, Seattle, and colleagues evaluated the effectiveness of applying oral syrup containing xylitol among 94 children age 9 to 15 months in the Republic of the Marshall Islands, where early childhood tooth decay is a serious health care problem.

Two active treatment groups received 8 grams per day of xylitol syrup divided into two (33 children) or three (32 children) doses per day. A third, control group of 29 children received a small amount (a single 2.67-gram dose) of xylitol syrup per day because the internal review committee appointed by the secretary of health of the Republic of the Marshall Islands did not permit the use of a placebo.

After an average of 10.5 months, eight of 33 children (24.2 percent) receiving two doses of xylitol per day and 13 of the 32 children (40.6 percent) receiving three doses of xylitol per day had tooth decay, compared with 15 of the 29 children (51.7 percent) in the control group. The average numbers of decayed teeth were 0.6 in the two-dose xylitol group, one in the three-dose xylitol group and 1.9 in the control group.

"Our results suggest that exposure to xylitol (8 grams per day) in a twice-daily topical oral syrup during primary tooth eruption could prevent up to 70 percent of decayed teeth," the authors write. "Dividing the 8 grams into three doses did not increase the effectiveness of the treatment. These results provide evidence for the first time (to our knowledge) that xylitol is effective for the prevention of decay in primary teeth of toddlers." More research is needed to develop vehicles and strategies for optimal public health, but in populations with high rates of tooth decay, xylitol is likely to be a cost-effective preventive measure, they conclude.

"Early childhood caries is well understood by microbiologists and research dentists—if not by the general public and their health care providers—as ordinary tooth decay run amok," writes Burton L. Edelstein, D.D.S., M.P.H., of the College of Dental Medicine, Columbia University, in an accompanying editorial.

"It most commonly manifests as extensive tooth destruction and associated pain, with or without infection, by age 22 months and sometimes much earlier," Dr. Edelstein continues. "The Centers for Disease Control and Prevention reports that more than one-quarter of all U.S. toddlers and preschoolers (28 percent) are affected."

"Findings reported herein by Milgrom and colleagues that xylitol application holds strong promise to significantly dampen early childhood caries occurrence are encouraging and suggest the addition of this approach to pharmacologic management in public health and individual care settings. Xylitol application, like fluoride varnish application, will likely become a routine element of early childhood caries control. The finding, however, that early childhood caries prevalence remained at 24 percent to 41 percent among treated children at the close of the trial in a high-caries-experience population reminds us that no single 'silver bullet' is going to solve the problem of early childhood caries."

Wednesday, July 1, 2009

Treatment for Receding Gums: No Pain, Lots of Gain

Tufts Dental Researchers Show Tissue Regeneration Application

Tufts dental researchers conducted a three-year follow-up study that examined the stability of a treatment option for receding gums and found that complete root coverage — the goal of the surgery — had been maintained. This specific tissue regeneration application, developed at Tufts, reduces the considerable pain and recovery time of gum grafting surgery. The case study of six patients is published in the July 2009 issue of the Journal of Periodontology.

“Patients have a less invasive treatment option for receding gums and we now have evidence to support the stability of this relatively painless procedure. Instead of leaving the dental office with stitches in the roof of their mouth, a patient leaves with a small bandage on the arm that can be removed in an hour,” said Terrence Griffin, DMD, associate professor, chair of the department of periodontology, and director of postdoctoral periodontology at Tufts University School of Dental Medicine in Boston.

“One of our previous research studies showed that all of the post-operative bleeding and most of the post-operative pain were related to the gum tissue removed from the roof of the mouth for use as a graft,” he continued.

Traditional gum grafting surgery requires surgically excising tissue from the roof of the mouth (the palate) to replace the gum tissue lost around the teeth. Unfortunately, removing tissue from the roof of the mouth extends recovery time and is a major source of patients’ discomfort or pain. According to the American Academy of Periodontology, periodontal disease is the primary cause of tooth loss in adults aged 35 and older. Periodontal disease includes gum recession, also called gingival recession, which can result in tooth root decay and tooth loss.

The new tissue regeneration application from Tufts uses platelet concentrate gel applied to a collagen membrane as the graft instead of using tissue from the roof of the mouth. The graft is soaked in the patient’s platelets, using blood drawn in the same visit. Placed over the receding tooth root, the graft is then surgically secured.

In order to examine three-year efficacy of the treatment, measurements were taken from six patients in the gum recession area at baseline, 6, and 36 months after surgery. At six months, 24 out of 37 teeth from the six patients had complete root coverage (65 percent). At 36 months, 21 out of 37 teeth from the six patients had complete root coverage (57 percent). The authors said that the recession over three years was minimal and that the results are comparable to traditional gum grafting surgery.

“Our previous research determined that pain and discomfort were barriers to receiving traditional gum grafting surgery.* We have also shown previously that this treatment for gum recession results in proper coverage of the tooth root, better esthetics than those found with traditional gum grafting surgery, and enhanced patient satisfaction with the results,”** said co-author Wai Cheung, DMD, MS, assistant professor in the department of periodontology at Tufts University School of Dental Medicine.

Over the last decade, Griffin and his colleagues, including Cheung, have studied alternatives to traditional gum grafting surgery and have more than 20 publications on the topic.

“Gum disease affects most American adults and research is linking periodontal disease to other health problems, including heart disease. Encouraging patients to undergo surgery to fix receding gums can be difficult because the mere thought of this dental surgery is often associated with considerable pain. This treatment, while only marginally more expensive for the patient, is more time-consuming and technically more difficult for us but the end result — improved esthetics, reduced pain, and, most importantly, improved oral health for the patient — make it a valuable and important alternative,” said Griffin.

Griffin TJ, Cheung WS. Journal of Periodontology. 2009. (July); 80 (7): 1192-1199. “Guided tissue regeneration-based root coverage with a platelet concentrate graft: A 3-year follow-up case series.” Published online July 1, 2009, doi: 10.1902/jop.2009.080609

* Griffin TJ, Cheung WS, Zavras AI, and Damoulis PD. Journal of Periodontology. 2006. (December); 77(12): 2070-2079. “Postoperative complications following gingival augmentation procedures.”

**Cheung WS, Griffin TJ. Journal of Periodontology. 2004. (December); 75 (12): 1678-1687. “A comparative study of root coverage with connective tissue and platelet concentrate grafts: 8-month results.”

Nanotechnology adds to longevity of dental fillings

Tooth-colored fillings may be more attractive than silver ones, but the bonds between the white filling and the tooth quickly age and degrade. A Medical College of Georgia researcher hopes a new nanotechnology technique will extend the fillings' longevity.

"Dentin adhesives bond well initially, but then the hybrid layer between the adhesive and the dentin begins to break down in as little as one year," says Dr. Franklin Tay, associate professor of endodontics in the MCG School of Dentistry. "When that happens, the restoration will eventually fail and come off the tooth."

Half of all tooth-colored restorations, which are made of composite resin, fail within 10 years, and about 60 percent of all operative dentistry involves replacing them, according to research in the Journal of the American Dental Association.

"Our adhesives are not as good as we thought they were, and that causes problems for the bonds," Dr. Tay says.

To make a bond, a dentist etches away some of the dentin's minerals with phosphoric acid to expose a network of collagen, known as the hybrid layer. Acid-etching is like priming a wall before it's painted; it prepares the tooth for application of an adhesive to the hybrid layer so that the resin can latch on to the collagen network. Unfortunately, the imperfect adhesives leave spaces inside the collagen that are not properly infiltrated with resin, leading to the bonds' failure.

Dr. Tay is trying to prevent the aging and degradation of resin-dentin bonding by feeding minerals back into the collagen network. With a two year, $252,497 grant from the National Institute of Dental & Craniofacial Research, he will investigate guided tissue remineralization, a new nanotechnology process of growing extremely small, mineral-rich crystals and guiding them into the demineralized gaps between collagen fibers.

His idea came from examining how crystals form in nature. "Eggshells and abalone [sea snail] shells are very strong and intriguing," Dr. Tay says. "We're trying to mimic nature, and we're learning a lot from observing how small animals make their shells."

The crystals, called hydroxyapatite, bond when proteins and minerals interact. Dr. Tay will use calcium phosphate, a mineral that's the primary component of dentin, enamel and bone, and two protein analogs also found in dentin so he can mimic nature while controlling the size of each crystal.

Crystal size is the real challenge, Dr. Tay says. Most crystals are grown from one small crystal into a larger, homogeneous one that is far too big to penetrate the spaces within the collagen network. Instead, Dr. Tay will fit the crystal into the space it needs to fill. "When crystals are formed, they don't have a definite shape, so they are easily guided into the nooks and crannies of the collagen matrix," he says.

In theory, the crystals should lock the minerals into the hybrid layer and prevent it from degrading. If Dr. Tay's concept of guided tissue remineralization works, he will create a delivery system to apply the crystals to the hybrid layer after the acid-etching process.

"Instead of dentists replacing the teeth with failed bonds, we're hoping that using these crystals during the bond-making process will provide the strength to save the bonds," Dr. Tay says. "Our end goal is that this material will repair a cavity on its own so that dentists don't have to fill the tooth."