Dental anesthesia may interrupt development of wisdom teeth in children

Researchers from Tufts University School of Dental Medicine have discovered a statistical association between the injection of local dental anesthesia given to children ages two to six and evidence of missing lower wisdom teeth. The results of this epidemiological study, published in the April issue of The Journal of the American Dental Association, suggest that injecting anesthesia into the gums of young children may interrupt the development of the lower wisdom tooth.

"It is intriguing to think that something as routine as local anesthesia could stop wisdom teeth from developing. This is the first study in humans showing an association between a routinely- administered, minimally-invasive clinical procedure and arrested third molar growth," said corresponding author, Anthony R. Silvestri, D.M.D., clinical professor in the department of prosthodontics and operative dentistry at Tufts University School of Dental Medicine.

Wisdom teeth are potentially vulnerable to injury because their development – unlike all other teeth – does not begin until well after birth. Between two and six years of age, wisdom tooth (third molar) buds begin to develop in the back four corners of the mouth, and typically emerge in the late teens or early adulthood. Not everyone develops wisdom teeth, but for those who do, the teeth often become impacted or problematic.

The American Association of Oral and Maxillofacial Surgeons reports that nine out of 10 people will have at least one impacted wisdom tooth, which can cause bad breath, pain, and/or infection. For this reason, many dentists recommend surgery to remove wisdom teeth to prevent disease or infection.

A developing wisdom tooth, called a bud, is vulnerable to injury for a relatively long time because it is tiny, not covered by bone, and only covered by a thin layer of soft tissue. When a tooth bud first forms, it is no bigger than the diameter of the dental needle itself. The soft tissue surrounding the budding tooth is close to where a needle penetrates when routine dental anesthesia is injected in the lower jaw, for example when treating cavities.

Using the Tufts digital dental record system, the researchers identified records of patients who had received treatment in the Tufts pediatric dental clinic between the ages of two and six and who also had a dental x-ray taken three or more years after initial treatment in the clinic. They eliminated records with confounding factors, such as delayed dental development, and analyzed a total of 439 sites where wisdom teeth could develop in the lower jaw, from 220 patient records.

Group one, the control group (376 sites), contained x-rays of patients who had not received anesthesia on the lower jaw where wisdom teeth could develop. Group two, the comparison group (63 sites), contained x-rays from patients who had received anesthesia.

In the control group, 1.9% of the sites did not have x-ray evidence of wisdom tooth buds. In contrast, 7.9% of the sites in the comparison group – those who had received anesthesia – did not have tooth buds. The comparison group was 4.35 times more likely to have missing wisdom tooth buds than the control group.

"The incidence of missing wisdom teeth was significantly higher in the group that had received dental anesthesia; statistical evidence suggests that this did not happen by chance alone. We hope our findings stimulate research using larger sample sizes and longer periods of observation to confirm our findings and help better understand how wisdom teeth can be stopped from developing," Silvestri continued. "Dentists have been giving local anesthesia to children for nearly 100 years and may have been preventing wisdom teeth from forming without even knowing it. Our findings give hope that a procedure preventing third molar growth can be developed."

Silvestri has previously published preliminary research on third molar tooth development, showing that third molars can be stopped from developing when non- or minimally-invasive techniques are applied to tooth buds.

Dental bib clips can harbor oral and skin bacteria even after disinfection

40 percent of bib clips retained aerobic bacteria; 70 percent retained anaerobic bacteria post-disinfection

Researchers at Tufts University School of Dental Medicine and the Forsyth Institute published a study today, "Comprehensive Analysis of Aerobic and Anaerobic Bacteria Found on Dental Bib Clips at Hygiene Clinic", that found that a significant proportion of dental bib clips harbored bacteria from the patient, dental clinician and the environment even after the clips had undergone standard disinfection procedures in a hygiene clinic. Although the majority of the thousands of bacteria found on the bib clips immediately after treatment were adequately eliminated through the disinfection procedure, the researchers found that 40% of the bib clips tested post-disinfection retained one or more aerobic bacteria, which can survive and grow in oxygenated environments. They found that 70% of bib clips tested post-disinfection retained one or more anaerobic bacteria, which do not live or grow in the presence of oxygen.

"The study of bib clips from the hygiene clinic demonstrates that with the current disinfection protocol, specific aerobic and anaerobic bacteria can remain viable on the surfaces of bib clips immediately after disinfection," said Addy Alt-Holland, M.Sc., Ph.D., Assistant Professor at the Department of Endodontics at Tufts University School of Dental Medicine and the lead researcher on the study. "Although actual transmission to patients was not demonstrated, some of the ubiquitous bacteria found may potentially become opportunistic pathogens in appropriate physical conditions, such as in susceptible patients or clinicians."

The study analyzed the clips on 20 dental bib holders after they had been used on patients treated in a dental hygiene clinic. The bib clips were sampled for aerobic and anaerobic bacterial contaminants immediately after treatment (post-treatment clips) and again after the clips were cleaned using disinfecting, alcohol-containing wipes (post-disinfection clips) according to the manufacturer instructions and the clinic's disinfection protocol.

Led by Dr. Bruce Paster, Chair of the Department of Microbiology at the Forsyth Institute, microbiologists at the Forsyth Institute used standard molecular identification techniques and a proprietary, one-of-a-kind technology that can detect 300 of the most prevalent oral bacteria, to analyze the sampled bacteria from the bib clips. The analyses found:

Immediately after treatment and before the clips had been disinfected, oral bacteria often associated with chronic and refractory periodontitis were found on 65% of the clips.
After disinfection, three of the bib clips (15%) still had anaerobic Streptococcus bacteria from the oral cavity and upper respiratory tract. Five percent (5%) of the clips still harbored at least one bacteria from the Staphylococcus, Prevotella and Neisseria species.
Additionally, after disinfection, nine clips (45%) retained at least one anaerobic bacterial isolate from skin.
"The results of our analysis show that there is indeed a risk of cross-contamination from dental bib clips. The previous patient's oral bacteria could potentially still be on the clip and the new patient has a chance of being exposed to infection by using that same bib clip," said Dr. Paster. "It is important to the clinician and the patient that the dental environment be as sterile as possible; thus it's concerning that we found bacteria on the clips after disinfection. This situation can be avoided by thoroughly sterilizing the clips between each patient or by using disposable bib holders."

Researchers involved in the study hypothesized that bacteria found on bib clips after patient care could have been transferred from patients and clinicians to the clips in different ways:

Oral bacteria present in the patient's saliva and the spray or spatter produced during dental treatments may contribute to the presence of bacteria on the disinfected bib clips.
Bacteria can also be transferred from the gloved hands of dental practitioners to the clips prior to- or during the patient's treatment.
Bacteria can be transferred from the patient's hands to the clips if the patient touches the clip.
In a previous study published in August 2012 by researchers at Tufts University School of Dental Medicine and the Forsyth Institute it was found that 20% to 30% of dental bib clips still harbor aerobic bacterial contaminants even after proper disinfection procedures. Rubber-faced metal bib clips were found to retain more bacteria than bib clips made only of metal immediately after treatment and before disinfection. Four other research reports have found bacterial contamination on dental bib holders, including research conducted by U.S. infection control specialist Dr. John Molinari, the University of North Carolina at Chapel Hill's School of Dentistry Oral Microbiology lab and the University of Witten/Herdecke in Germany.

Mercury test may overestimate exposure from dental amalgam fillings

A common test used to determine mercury exposure from dental amalgam fillings may significantly overestimate the amount of the toxic metal released from fillings, according to University of Michigan researchers.

Scientists agree that dental amalgam fillings slowly release mercury vapor into the mouth. But both the amount of mercury released and the question of whether this exposure presents a significant health risk remain controversial.

Public health studies often make the assumption that mercury in urine (which is composed mostly of inorganic mercury) can be used to estimate exposure to mercury vapor from amalgam fillings. These same studies often use mercury in hair (which is composed mostly of organic mercury) to estimate exposure to organic mercury from a person's diet.

But a U-M study that measured mercury isotopes in the hair and urine from 12 Michigan dentists found that their urine contained a mix of mercury from two sources: the consumption of fish containing organic mercury and inorganic mercury vapor from the dentists' own amalgam fillings.

"These results challenge the common assumption that mercury in urine is entirely derived from inhaled mercury vapor," said Laura Sherman, a postdoctoral research fellow in the Department of Earth and Environmental Sciences and lead author of a paper in the journal Environmental Science & Technology. A final version of the paper was published online March 20.

"These data suggest that in populations that eat fish but lack occupational exposure to mercury vapor, mercury concentrations in urine may overestimate exposure to mercury vapor from dental amalgams. This is an important consideration for studies seekingMeasuring mercury: Common test may overestimate exposure from dental amalgam fillings

ANN ARBOR—A common test used to determine mercury exposure from dental amalgam fillings may significantly overestimate the amount of the toxic metal released from fillings, according to University of Michigan researchers.

Scientists agree that dental amalgam fillings slowly release mercury vapor into the mouth. But both the amount of mercury released and the question of whether this exposure presents a significant health risk remain controversial.

Public health studies often make the assumption that mercury in urine (which is composed mostly of inorganic mercury) can be used to estimate exposure to mercury vapor from amalgam fillings. These same studies often use mercury in hair (which is composed mostly of organic mercury) to estimate exposure to organic mercury from a person's diet.

But a U-M study that measured mercury isotopes in the hair and urine from 12 Michigan dentists found that their urine contained a mix of mercury from two sources: the consumption of fish containing organic mercury and inorganic mercury vapor from the dentists' own amalgam fillings.

"These results challenge the common assumption that mercury in urine is entirely derived from inhaled mercury vapor," said Laura Sherman, a postdoctoral research fellow in the Department of Earth and Environmental Sciences and lead author of a paper in the journal Environmental Science & Technology. A final version of the paper was published online March 20.

"These data suggest that in populations that eat fish but lack occupational exposure to mercury vapor, mercury concentrations in urine may overestimate exposure to mercury vapor from dental amalgams. This is an important consideration for studies seeking to determine the health risks of mercury vapor inhalation from dental amalgams," said U-M biogeochemist Joel D. Blum, a co-author of the paper and a professor in the Department of Earth and Environmental Sciences.

The study by Sherman, Blum and their colleagues demonstrates that mercury isotopes can be used to more accurately assess human exposure to the metal—and the related health risks—than traditional measurements of mercury concentrations in hair and urine samples. Specifically, isotopes provide a novel chemical tracer that can be used to "fingerprint" both organic mercury from fish and inorganic mercury vapor from dental amalgams.

Mercury is a naturally occurring element, but more than 2,000 tons are emitted into the atmosphere each year from human-generated sources such as coal-fired power plants, small-scale gold-mining operations, metals and cement production, incineration and caustic soda production.

This mercury is deposited onto land and into water, where micro-organisms convert some of it to methylmercury, a highly toxic organic form that builds up in fish and the animals that eat them, including humans. Effects on humans include damage to the central nervous system, heart and immune system. The developing brains of fetuses and young children are especially vulnerable.

Inorganic mercury can also cause central nervous system and kidney damage. Exposure to inorganic mercury occurs primarily through the inhalation of elemental mercury vapor. Industrial workers and gold miners can be at risk, as well as dentists who install mercury amalgam fillings—though dentists have increasingly switched to resin-based composite fillings and restorations in recent years.

About 80 percent of inhaled mercury vapor is absorbed into the bloodstream in the lungs and transported to the kidneys, where it is excreted in urine. Because the mercury found in urine is almost entirely inorganic, total mercury concentrations in urine are commonly used as an indicator, or biomarker, for exposure to inorganic mercury from dental amalgams.

But the study by Sherman, Blum and their colleagues suggests that urine contains a mix of inorganic mercury from dental amalgams and methylmercury from fish that undergoes a type of chemical breakdown in the body called demethylation. The demethylated mercury from fish contributes significantly to the amount of inorganic mercury in the urine.

The U-M scientists relied on a natural phenomenon called isotopic fractionation to distinguish between the two types of mercury. All atoms of a particular element contain the same number of protons in their nuclei. However, a given element can have various forms, known as isotopes, each with a different number of neutrons in it nucleus.

Mercury has seven stable (nonradioactive) isotopes. During isotopic fractionation, different mercury isotopes react to form new compounds at slightly different rates. The U-M researchers relied on a type of isotopic fractionation called mass-independent fractionation to obtain the chemical fingerprints that enabled them to distinguish between exposure to methylmercury from fish and mercury vapor from dental amalgam fillings. to determine the health risks of mercury vapor inhalation from dental amalgams," said U-M biogeochemist Joel D. Blum, a co-author of the paper and a professor in the Department of Earth and Environmental Sciences.

The study by Sherman, Blum and their colleagues demonstrates that mercury isotopes can be used to more accurately assess human exposure to the metal—and the related health risks—than traditional measurements of mercury concentrations in hair and urine samples. Specifically, isotopes provide a novel chemical tracer that can be used to "fingerprint" both organic mercury from fish and inorganic mercury vapor from dental amalgams.

Mercury is a naturally occurring element, but more than 2,000 tons are emitted into the atmosphere each year from human-generated sources such as coal-fired power plants, small-scale gold-mining operations, metals and cement production, incineration and caustic soda production.

This mercury is deposited onto land and into water, where micro-organisms convert some of it to methylmercury, a highly toxic organic form that builds up in fish and the animals that eat them, including humans. Effects on humans include damage to the central nervous system, heart and immune system. The developing brains of fetuses and young children are especially vulnerable.

Inorganic mercury can also cause central nervous system and kidney damage. Exposure to inorganic mercury occurs primarily through the inhalation of elemental mercury vapor. Industrial workers and gold miners can be at risk, as well as dentists who install mercury amalgam fillings—though dentists have increasingly switched to resin-based composite fillings and restorations in recent years.

About 80 percent of inhaled mercury vapor is absorbed into the bloodstream in the lungs and transported to the kidneys, where it is excreted in urine. Because the mercury found in urine is almost entirely inorganic, total mercury concentrations in urine are commonly used as an indicator, or biomarker, for exposure to inorganic mercury from dental amalgams.

But the study by Sherman, Blum and their colleagues suggests that urine contains a mix of inorganic mercury from dental amalgams and methylmercury from fish that undergoes a type of chemical breakdown in the body called demethylation. The demethylated mercury from fish contributes significantly to the amount of inorganic mercury in the urine.

The U-M scientists relied on a natural phenomenon called isotopic fractionation to distinguish between the two types of mercury. All atoms of a particular element contain the same number of protons in their nuclei. However, a given element can have various forms, known as isotopes, each with a different number of neutrons in it nucleus.

Mercury has seven stable (nonradioactive) isotopes. During isotopic fractionation, different mercury isotopes react to form new compounds at slightly different rates. The U-M researchers relied on a type of isotopic fractionation called mass-independent fractionation to obtain the chemical fingerprints that enabled them to distinguish between exposure to methylmercury from fish and mercury vapor from dental amalgam fillings.

Fluoride in Drinking Water Cuts Tooth Decay in Adults

A new study conducted by researchers at the University of North Carolina at Chapel Hill and the University of Adelaide, Australia, has produced the strongest evidence yet that fluoride in drinking water provides dental health benefits to adults, even those who had not received fluoridated drinking water as children.

In the first population-level study of its kind, the study shows that fluoridated drinking water prevents tooth decay for all adults regardless of age, and whether or not they consumed fluoridated water during childhood.

Led by UNC School of Dentistry faculty member Gary Slade, the study adds a new dimension to evidence regarding dental health benefits of fluoridation.

"It was once thought that fluoridated drinking water only benefited children who consumed it from birth," explained Slade, who is John W. Stamm Distinguished Professor and director of the oral epidemiology Ph.D. program at UNC. "Now we show that fluoridated water reduces tooth decay in adults, even if they start drinking it after childhood. In public health terms, it means that more people benefit from water fluoridation than previously thought."

The researchers analyzed national survey data from 3,779 adults aged 15 and older selected at random from the Australian population between 2004 and 2006. Survey examiners measured levels of decay and study participants reported where they lived since 1964. The residential histories of study participants were matched to information about fluoride levels in community water supplies. The researchers then determined the percentage of each participant's lifetime in which the public water supply was fluoridated.

The results, published online in the Journal of Dental Research, show that adults who spent more than 75 percent of their lifetime living in fluoridated communities had significantly less tooth decay (up to 30 percent less) when compared to adults who had lived less that 25 percent of their lifetime in such communities.

"At this time, when several Australian cities are considering fluoridation, we should point out that the evidence is stacked in favor of long-term exposure to fluoride in drinking water," said Kaye Roberts-Thomson, a co-author of the study. "It really does have a significant dental health benefit."

Postmenopausal women who have smoked are at much higher risk of losing their teeth

Postmenopausal women who have smoked are at much higher risk of losing their teeth than women who never smoked, according to a new study published and featured on the cover of the Journal of the American Dental Association by researchers at the University at Buffalo.

The study involved 1,106 women who participated in the Buffalo OsteoPerio Study, an offshoot of the Women’s Health Initiative, (WHI), the largest clinical trial and observational study ever undertaken in the U.S., involving more than 162,000 women across the nation, including nearly 4,000 in Buffalo.

The UB study is the first to examine comprehensive smoking histories for participants that allowed the researchers to unravel some of the causes behind tooth loss in postmenopausal women who smoked.

The study, which appears in the journal’s current issue is available at http://jada.ada.org/content/144/3/252.full.

Smoking has long been associated with tooth loss, but postmenopausal women, in particular, experience more tooth loss than their male counterparts.

“Regardless of having better oral health practices, such as brushing and flossing, and visiting the dentist more frequently, postmenopausal women in general tend to experience more tooth loss than men of the same age,” says Xiaodan (pronounced Shee-ao-dan) Mai, a doctoral student in epidemiology in the UB Department of Social and Preventive Medicine in the School of Public Health and Health Professions. “We were interested in smoking as a variable that might be important.”

While fewer adults lose their teeth now than in past decades, tooth loss is associated with poor health outcomes, including stroke, cancer, rheumatoid arthritis and diabetes.

In the UB study, heavy smokers -- defined as those who had at least 26 pack-years of smoking, or the equivalent of having smoked a pack a day for 26 years -- were nearly twice as likely to report having experienced tooth loss overall and more than six times as likely to have experienced tooth loss due to periodontal disease, compared to those who never smoked.

Participants provided information to researchers using a detailed questionnaire covering smoking history. Each participant also underwent a comprehensive oral examination and reported to the dental examiners reasons for each tooth lost. In some cases, the patient’s dental records also were reviewed.

“We found that heavy smokers had significantly higher odds of experiencing tooth loss due to periodontal disease than those who never smoked,” explains Mai. “We also found that the more women smoked, the more likely they experienced tooth loss as a result of periodontal disease.”

On the other hand, they found that smoking was a less important factor in tooth loss due to caries. That’s an important distinction, says Mai.

“Periodontal disease is a chronic, inflammatory condition that may be related to the development of cancer,” she explains.

The paper notes that cigarette smoke may accelerate periodontal disease and that other studies suggest that chemicals found in smoke may favor plaque-forming bacteria that could reduce the ability of saliva to be antioxidative. Nicotine also has been shown to reduce bone density and bone mineral factors while estrogen hormones have been found to be lower among women who smoke.

Mai is now interested in pursuing research that could determine whether smokers with periodontal disease are at even greater risk for certain cancers than smokers without periodontal disease.

“Tooth loss due to periodontal disease is a prevalent condition among postmenopausal women that severely impacts their dietary intake, aesthetics, and overall quality of life,” says Mai. “Women now have yet another, very tangible reason for quitting smoking.”

- See more at: http://www.buffalo.edu/news/releases/2013/03/002.html#sthash.c2iyIrI2.dpuf

Using mouthrinse reduces plaque and gingivitis more than toothbrushing alone

New research published in the January/February 2013 issue of General Dentistry, the peer-reviewed clinical journal of the Academy of General Dentistry (AGD), indicates that the use of a germ-killing mouthrinse in addition to regular toothbrushing can significantly reduce plaque and gingivitis, more so than brushing alone.

"It's simple—mouthrinses can reach nearly 100 percent of the mouth's surfaces, while brushing focuses on the teeth, which make up only 25 percent of the mouth," says Christine A. Charles, RDH, BS, lead author of the study and director of Scientific and Professional Affairs, Global Consumer Healthcare Research and Development, Johnson & Johnson Consumer and Personal Products Worldwide.

"Even with regular brushing and flossing, bacteria often are left behind." The General Dentistry study found that using a germ-killing mouthrinse twice a day, in addition to regular brushing, can significantly reduce the occurrence of plaque, as well as gingivitis—the beginning stage of gum disease. The six-month study included 139 adults with mild to moderate plaque and gingivitis who were separated into two groups. Members of the first group brushed their teeth and rinsed with a germ-killing mouthrinse twice daily; members of the second group brushed their teeth and rinsed with a placebo mouthrinse twice daily.

"Results show that the group using a germ-killing mouthrinse reduced its occurrence of plaque by up to 26.3 percent," says AGD Spokesperson Janice Pliszczak, DDS, MS, MBA, MAGD. "Furthermore, that same group showed a 20.4 percent reduction in gingivitis." Additionally, following the six-month study, nearly 100 percent of participants using the germ-killing mouthrinse showed a reduction in gingivitis, while only 30 percent of the placebo group experienced similar results. "The study demonstrates the oral health benefits of regular and consistent daily use of a germ-killing mouthrinse," says Ms. Charles.

"Most people brush their teeth for less than 1 minute, when, at the very least, they should be brushing for 2 minutes. Additionally, only 2 to 10 percent of people floss regularly and effectively," adds Dr. Pliszczak. "Adding a germ-killing mouthrinse twice a day to your daily routine is another way to attack the germs that can cause significant oral health problems." Dr. Pliszczak notes that not all mouthrinses are formulated to kill germs—some are meant for anti-cavity or whitening purposes—so be sure to read product labels.

Being overweight linked to higher risk of gum disease

Impacting approximately one-third of the U.S. population, obesity is a significant health concern for Americans. It's a risk factor for developing type 2 diabetes, heart disease, and certain forms of cancer, and now, according to an article published in the January/February 2013 issue of General Dentistry, the peer-reviewed clinical journal of the Academy of General Dentistry (AGD), it also may be a risk factor for gum disease.

"We know that being overweight can affect many aspects of a person's health," says Charlene Krejci, DDS, MSD, lead author of the article. "Now researchers suspect a link exists between obesity and gum disease. Obese individuals' bodies relentlessly produce cytokines, proteins with inflammatory properties. These cytokines may directly injure the gum tissues or reduce blood flow to the gum tissues, thus promoting the development of gum disease."

Half of the U.S. population age 30 and older is affected by gum disease—a chronic inflammatory infection that impacts the surrounding and supporting structures of the teeth. Gum disease itself produces its own set of cytokines, which further increases the level of these inflammatory proteins in the body's bloodstream, helping to set off a chain reaction of other inflammatory diseases throughout the body. Research on the relationship between obesity and gum disease is still ongoing.

"Whether one condition is a risk factor for another or whether one disease directly causes another has yet to be discovered," says AGD Spokesperson Samer G. Shamoon, DDS, MAGD. "What we do know is that it's important to visit a dentist at least twice a year so he or she can evaluate your risks for developing gum disease and offer preventive strategies."

The best way to minimize the risk of developing gum disease is to remove plaque through daily brushing, flossing, rinsing, and professional cleanings. "A dentist can design a personalized program of home oral care to meet each patient's specific needs," says Dr. Shamoon.