Monday, March 26, 2012

Dental plaque bacteria may trigger blood clots

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Oral bacteria that escape into the bloodstream are able to cause blood clots and trigger life-threatening endocarditis. Further research could lead to new drugs to tackle infective heart disease, say scientists presenting their work at the Society for General Microbiology's Spring Conference in Dublin this week.

Streptococcus gordonii is a normal inhabitant of the mouth and contributes to plaque that forms on the surface of teeth. If these bacteria enter into the blood stream through bleeding gums they can start to wreak havoc by masquerading as human proteins.

Researchers from the Royal College of Surgeons in Ireland (RCSI) and the University of Bristol have discovered that S. gordonii is able to produce a molecule on its surface that lets it mimic the human protein fibrinogen – a blood-clotting factor. This activates the platelets, causing them to clump inside blood vessels. These unwanted blood clots encase the bacteria, protecting them from the immune system and from antibiotics that might be used to treat infection. Platelet clumping can lead to growths on the heart valves (endocarditis), or inflammation of blood vessels that can block the blood supply to the heart or brain.

Dr Helen Petersen who is presenting the work said that better understanding of the relationship between bacteria and platelets could ultimately lead to new treatments for infective endocarditis. "In the development of infective endocarditis, a crucial step is the bacteria sticking to the heart valve and then activating platelets to form a clot. We are now looking at the mechanism behind this sequence of events in the hope that we can develop new drugs which are needed to prevent blood clots and also infective endocarditis," she said.

Infective endocarditis is treated with surgery or by strong antibiotics – which is becoming more difficult with growing antibiotic resistance. "About 30% of people with infective endocarditis die and most will require surgery for replacement of the infected heart valve with a metal or animal valve," said Dr Petersen. "Our team has now identified the critical components of the S. gordonii molecule that mimics fibrinogen, so we are getting closer to being able to design new compounds to inhibit it. This would prevent the stimulation of unwanted blood clots," said Dr Steve Kerrigan from the RCSI.

The team are also looking more widely at other dental plaque bacteria that may have similar effects to S. gordonii. "We are also trying to determine how widespread this phenomenon is by studying other bacteria related to S. gordonii. What our work clearly shows is how important it is to keep your mouth healthy through regular brushing and flossing, to keep these bacteria in check," stressed Dr Petersen.

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New 'massage method' quadruples protection against tooth decay

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Do you really want to avoid cavities in your teeth? Try massaging them with a high-fluoride toothpaste after lunch. "Rubbing toothpaste onto your teeth increases the fluoride protection by 400%," says Anna Nordström, dentist, PhD and researcher at the Sahlgrenska Academy at the University of Gothenburg, Sweden.

Eight years ago a new brand of toothpaste was launched in Sweden with more than three times as much fluoride as standard toothpaste. Available without prescription, it is aimed primarily at those with high caries risk.

First scientific evaluation


Researchers at the University of Gothenburg's Sahlgrenska Academy have now performed the first scientific evaluation of the effect of this so called "high-fluoride toothpaste". The study has resulted in a new method that quadruples the level of protection from fluoride.

Four times better protection

In the study, 16 volunteers tested a variety of brushing techniques, using either high-fluoride or standard toothpaste, and brushing either two or three times a day. "The study revealed that those who used a high-fluoride toothpaste three times a day had four times better fluoride protection in the mouth than those who used standard toothpaste twice a day," says researcher Anna Nordström from the Institute of Odontology at the Sahlgrenska Academy.

Rub your teeth after lunch

Also tested was a new method developed in collaboration with professor Dowen Birkhed, which involves rubbing toothpaste onto your teeth with a finger. "This 'massage' method proved to be at least as effective as a third brushing in increasing the amount of fluoride in the mouth," Anna Nordström explains. "Rubbing the front of your teeth with toothpaste can be an easy way of giving your teeth a third "shot" of fluoride during the day, after lunch for example. But this should not replace brushing with a fluoride toothpaste morning and evening – it's an extra."

Daily use is essential


Brushing with fluoride toothpaste has played – and continues to play – a major role in combating tooth decay, and there is strong scientific evidence that daily use of fluoride toothpaste has a pronounced preventive effect.

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The study Effect of a third application of toothpaste (1450 and 5000 ppm F), including a "massage" method, on fluoride retention and pH drop in plaque was published in Acta Odontologica Scandinavia.

Link to article: http://www.ncbi.nlm.nih.gov/pubmed/22320714

Friday, March 23, 2012

Periodontal therapy reduces hospitalizations and medical care costs in diabetics

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Today, during the 41st Annual Meeting & Exhibition of the American Association for Dental Research (AADR), held in conjunction with the 36th Annual Meeting of the Canadian Association for Dental Research, an abstract titled "Periodontal Therapy Reduces Hospitalizations and Medical Care Costs in Diabetics" to determine if periodontal treatment was associated with the number of hospitalizations and cost of medical care among diabetics with periodontal disease.

A longitudinal study compared medical costs for diabetic subjects with periodontal disease who received periodontal treatment versus periodontally untreated controls over a three year period. Subjects were enrolled in Highmark (Blue Cross) medical and United Concordia Companies, Inc. dental plans, and received medical and dental services. The periodontal treatment group was treated in the first year and maintained thereafter. The control group had received incomplete periodontal therapy prior to baseline and did not receive regular maintenance during the study.

"There have been emerging links between oral infections and systemic diseases such as diabetes, which is increasingly prevalent in our population," said lead researcher Marjorie Jeffcoat, professor and dean emeritus of the University of Pennsylvania School of Dental Medicine. "My research team and I had looked at other datasets and we knew that health care costs could be reduced, but we wanted to look at the hospitalizations and see how those could be reduced. This study provided direct insight as to how lower hospitalizations could be achieved through periodontal therapy, and we will further this study by analyzing other chronic diseases and conditions such as heart attacks, strokes and pregnancy with pre-term birth."

Periodontal treatment was associated with a significant decrease in hospital admissions, physician visits and overall cost of medical care in diabetics. Savings averaged $1,814 per patient in a single year. A 33% decrease in hospital admissions was observed.

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Friday, March 16, 2012

Poor dental hygiene puts congenital heart disease patients at risk of further heart damage

Poor dental hygiene behaviours in patients with congenital heart disease are increasing their risk of endocarditis. Teens with congenital heart disease floss, brush and visit the dentist less than their peers. But they have healthier behaviours when it comes to alcohol, cigarettes and illicit drugs. Adults with single ventricle physiology (a type of congenital heart disease) also have poorer dental hygiene practices than their peers despite having better health behaviours overall.

The findings were presented in two studies at the 12th Annual Spring Meeting on Cardiovascular Nursing, 16-17 March, in Copenhagen, Denmark.

"Patients with congenital heart disease are diagnosed and receive their initial treatment in childhood but this does not mean that they are cured," says the supervisor of both studies, Professor Philip Moons, professor in nursing science at the University of Leuven, Belgium, and guest professor at Copenhagen University Hospital, Denmark. "They remain vulnerable for developing complications – for instance we know that in patients with congenital heart disease, binge drinking can trigger life-threatening arrhythmias and good dental hygiene helps prevent endocarditis."

For the first study (FPN 34) 1, lifestyle information was collected from 429 adolescents with congenital heart disease aged 14-19 years from the longitudinal study i-DETACH (Information technology Devices and Education programme for Transitioning Adolescents with Congenital Heart disease). Of these, 401 were matched with a control of the same age and gender without congenital heart disease. All participants completed a questionnaire, developed by the research group of Professor Moons, which measures the use of alcohol, cigarettes and illicit drugs, dental care and physical activity. These behaviours are particularly important to the health of patients with congenital heart disease.

Using results from the questionnaire, the researchers calculated risk scores for 'substance use' (binge drinking; smoking; illicit drug use) and 'dental hygiene' (no dental visits; not brushing; not flossing) ranging from 0𔃁. An 'overall health risk score' (range 0𔃅) was calculated using the substance use risk score, dental hygiene risk score, and the absence of physical activity. The 3 risk scores were transformed to a scale ranging from 0 (no risk) to 100 (maximum risk). Scores were compared across different age groups.

In adolescents with congenital heart disease, substance use increased with age (p<0.001). Compared with matched controls, adolescents with congenital heart disease had significantly lower substance use (p<0.001) and health risk (p<0.001) scores, and significantly higher dental hygiene risk scores (p=0.04).

The results reveal that health risk behaviours are prevalent in adolescents with congenital heart disease and they increase with age. They also show that in general, the health behaviour of adolescents with congenital heart disease is better than their peers except for dental hygiene.

Professor Moons says: "The fact that adolescents with congenital heart disease have better health behaviour overall than the general population is understandable given the amount of input they have had from healthcare professionals over their lives. But we need to do more to understand why their dental hygiene is not as good as expected."

For the second study (FPN 158)², the same questionnaire was used to collect lifestyle information from adults aged 16-48 years (average age 24 years) with a type of congenital heart disease called single ventricle physiology. "This is a very complex congenital heart condition and we know that these patients are more at risk for endocarditis and arrhythmias than the larger population of congenital heart disease patients," says Professor Moons. "This means that their health behaviour is even more important."

A cross sectional, case control study was conducted in 59 patients who were matched on age and gender to 172 healthy controls.

In patients with single ventricle physiology, 85% drank alcohol; 26% were binge drinkers; 20% smoked cigarettes; 12% used cannabis over the past year; 20% had not visited the dentist during the last year; 46% were not flossing teeth; and 39% were not physically active.

Compared to healthy controls, patients with single ventricle physiology had better health behaviours overall. But patients exercised less and their dental hygiene practices (mainly flossing) was poorer.

The only statistically significant differences between patients and controls were for binge drinking and physical activity. A significantly lower proportion of binge drinking was found in patients compared to controls (24% vs 41%). And patients exercised less than controls (61% vs 76%).

"Patients with complex conditions can have physical restrictions so the fact that they are less physically active is perhaps not surprising," says Professor Moons. "But the reasons behind the poorer dental hygiene practices of patients in both studies need to be investigated further."

In the past, efforts to prevent endocarditis in patients with congenital heart disease focused on taking antibiotics one hour before a dental procedure. This prevented bacteria released into the blood from damaged gums travelling to the heart and causing an infection (endocarditis).

But researchers have since discovered that daily dental hygiene is more important for preventing endocarditis than antibiotics before a procedure. Professor Moons says: "This was a change in the American Heart Association 2007 guidelines but not all physicians have switched to that new paradigm. And of course if you switch to that paradigm you also need to educate patients in a systematic way, but a lot of centres are not doing that yet."

He adds: "Systematic structured patient education on the importance of dental hygiene is critical for preventing endocarditis in patients with congenital heart disease."

Friday, March 9, 2012

Successful Dental Implants for Patients Taking Biphosphonates for Osteoporosis

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Reducing a patient’s treatment time and simplifying the treatment can increase patient acceptance and reduce the risk of complications. For dental implants, this means moving away from the traditional two-stage surgical approach toward a one-stage procedure. The success of this concept when combined with another complication—that of patients receiving drug therapy for osteoporosis—was studied to determine the best method of treatment in this situation.

The current issue of the Journal of Oral Implantology reports on adult patients, all taking oral biphosphonates for osteoporotic disease, who received fixed full-arch dental prostheses supported by six implants. Immediate loading procedures were performed, installing the implants in a one-stage surgery.

Osteoporosis is a well-known disease that weakens bone and increases the risk of fracture, particularly among postmenopausal women. Biphosphonates, an inhibitor of bone resorption, are widely used as a drug therapy for those with osteoporosis. Prolonged used of biphosphonates, however, can lead to a painful refractory bone exposure in the jaws, known as “biphosphonate-induced osteonecrosis of the jaw” (BONJ).

This condition usually develops after dental treatment, indicating that oral surgery and implants placed into the jaw bone can precipitate BONJ. Although the process is not fully understood, it appears that prolonged use of biphosphonates may suppress the bone’s repair function, interfering with healing after implants.

In the current study, a total of 54 implants were installed for nine osteoporotic patients, 45 to 68 years old, eight of them female. All had been taking oral biphosphonates for less than three years; a significant increase in risk of developing BONJ is associated with more than three years of biphosphonate therapy.

Immediate occlusal loading procedures were used, which require that motion at the bone-implant interface be kept below a certain threshold during healing. This study demonstrated a 100 percent success rate, with all patients rehabilitated with a full-arch prosthesis supported by implants. Two years of follow-up found no adverse events of infection, tissue swelling, or lesions, showing this to be a viable one-stage treatment.

Full text of the article, “Immediate Loading in Mandible Full-Arch: Pilot Study in Patients With Osteoporosis in Biphosphonate Therapy ,” Journal of Oral Implantology, Vol. 38, No. 1, 2012, is available at http://www.joionline.org/
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Wash Your Mouth out With Silver, to Treat Hard-To-Treat Mouth Infections?

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Yeasts which cause hard-to-treat mouth infections are killed using silver nanoparticles in the laboratory, scientists have found. These yeast infections, caused by Candida albicans and Candida glabrata target the young, old and immuno-compromised. Professor Mariana Henriques, University of Minho, and her colleagues hope to test silver nanoparticles in mouthwash and dentures as a potential preventative measure against these infections.

Professor Henriques and her team, who recently published their research in the Society for Applied Microbiology's journal Letters in Applied Microbiology, looked at the use of different sizes of silver nanoparticles to determine their anti-fungal properties against Candida albicans and Candida glabrata. These two yeasts cause infections including oral thrush and dental stomatitis, a painful infection affecting around seven out of ten denture wearers. Infections like these are particularly difficult to treat because the microorganisms involved form biofilms.

The scientists used artificial biofilms in conditions which mimic those of saliva as closely as possible. They then added different sizes and concentrations of silver nanoparticles and found that different sizes of nanoparticles were equally effective at killing the yeasts. Due to the diversity of the sizes of nanoparticles demonstrating anti-fungal properties the researchers hope this will enable the nanoparticles to be used in many different applications.

Some researchers have expressed concerns around the safety of nanoparticle use but the authors stress this research is at an early stage and extensive safety trials will be carried out before any product reaches the market.

Professor Henriques comments: With the emergence of Candida infections which are frequently resistant to the traditional antifungal therapies, there is an increasing need for alternative approaches. So, silver nanoparticles appear to be a new potential strategy to combat these infections. As the nanoparticles are relatively stable in liquid medium they could be developed into a mouthwash solution in the near future.

Moving forward Professor Henriques hopes to integrate silver nanoparticles into dentures which could prevent infections from taking hold.

Monday, March 5, 2012

Gum Healing Promoted Around Exposed Roots

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Receding gums often result in tooth sensitivity and can lead to decay of the root and persistent inflammation of the gum. New research published in BioMed Central's open access journal Head & Face Medicine demonstrates that a novel method using bovine collagen is able to enhance gum healing. This resulted in thicker margins around the tooth and, in over half the cases, complete coverage of exposed roots.

Researchers across Germany and Switzerland led by Dr Shahram Ghanaati and the dentist Dr Markus Schlee investigated the possibility of using collagen, extracted from bovine pericardium, to form a support for mending receding gums and exposed roots. The collagen was extracted by a process involving osmotic, oxidative and alkaline treatment. This ensured that the cell walls were broken down, proteins and fats dissolved, and that bacteria, viruses and other pathogens were inactivated and removed.

The study followed 14 otherwise healthy patients with over 60 'recessions' between them. Their damaged teeth were cleaned before surgery and the collagen implants held in place with loops of surgical thread around the affected tooth. Two weeks later the sutures were removed. None of the patients needed antibiotics.

The patients were re-examined after six months to see how well they had recovered. Dr Schlee described the results, "In all cases the healed-over implant improved the look and severity of the recession, and, in over half of all treatments, resulted in total coverage of the exposed root. We would not have expected any of these patients to get better without surgery."

The collagen seems to be able to act as a scaffold for the body's own cells to repair the damage leading to results on a level comparable to that of connective tissue grafts. Bovine collagen is a possible solution for patients with little available donor tissue or for whom multiple surgeries are not an option.

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Friday, March 2, 2012

An Unlikely Bond: Prenatal Health and Dental Hygiene

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Oral health doesn’t always top the list of concerns that expectant mothers may have, but it certainly should. Proper dental health and control of oral disease can safeguard a mother’s health before and during pregnancy and reduces the transmission of bacteria from women to their children. According to numerous studies by the American Congress of Obstetricians and Gynecologists, many women do not seek, nor are instructed to seek, proper oral healthcare as part of their routine prenatal care.

“Caring for a pregnant mother’s teeth and gums should start before she becomes pregnant,” said Doron Kochman, DDS and Associate Clinical Professor of Pediatric Dentistry in the Department of Clinical Dentistry, at the University of Rochester Strong Memorial Hospital, and Eastman Dental Center in Rochester, NY. “Ideally, women who are planning to get pregnant should visit their dentists and have any necessary work done before the pregnancy. Mothers should continue to visit their dentists for routine prevention visits during their pregnancies.”

Due to the natural hormonal fluctuations during pregnancy, gums are more susceptible to swelling and inflammation. Because of this, bacteria can accumulate causing gum disease and further medical complications for both mother and baby. “We now know that the bacteria responsible for gum disease can also cause problems in places other than the mother’s mouth,” said Kochman. Periodontal disease increases the risk that bacteria will enter the bloodstream, causing potential infections in either mother or baby.

Studies have shown a link between periodontal disease in mothers and an increased chance of delivering premature or low birth weight babies. Because many pregnant women routinely experience swollen and bleeding gums after they brush, they may not recognize a true problem if it exists. Regular check-ups before and during pregnancy are highly recommended.

In addition to prematurity and low birth weight, other problems can result from oral health issues. Studies have suggested that periodontal disease can increase the risk for preeclampsia, a life-threatening disorder caused by high blood pressure which usually occurs mid-to-late pregnancy.

People with diabetes are also more likely to have periodontal disease. Diabetic mothers need to be vigilant about their blood glucose levels to protect their unborn children from fetal obesity, high blood insulin levels and blood disorders, among other conditions.

Furthermore, there is growing evidence that if a mother’s oral hygiene is less than optimal, her baby’s oral health can suffer. “An expectant mother’s diet and oral hygiene can affect her baby's teeth,” said Kochman. “The baby’s teeth start developing in the 5th or 6th week after conception. A mother's balanced diet during pregnancy provides the calcium, phosphorous, other minerals and vitamins needed for the baby’s teeth to form properly.”

Most dentists recommend the following tips for expectant moms:
• Brush at least twice a day to remove plaque buildup
• Floss regularly
• Avoid sugary snacks
• Eat a healthy, balanced diet
• Get regular dental exams (speak to your dentist to see what is right for you)

Thursday, March 1, 2012

New method for stronger dental implants

Millions of people have bad teeth replaced with implants. Often following the procedure, they are unable to chew food for up to six months, until the implant has become fixated in the bone. Now, for the first time, a drug coating that has been tested on humans allows titanium screws to adhere to the bone better and faster. The Linköping researchers behind the method report that the results are good.

The study, led by Per Aspenberg, professor of orthopaedic surgery at Linköping University, is published in the journal Bone and was highlighted in this week's edition of the British Medical Journal (BMJ).

The implants are screwed into the jawbone and provide purchase for artificial teeth. Using current technology, it may take four to six months before the bone surrounding the screw has healed and is strong enough so the patient can begin to benefit from surgery.

The coating, developed at Linköping University in Sweden, consists of a nanometre-thin layer of protein that attaches to the metal surface. Attached to the protein is a drug belonging to the bisphosphonates, usually used to treat osteoporosis. Several animal studies have shown that this method allows the bone surrounding the implant to rapidly become denser and stronger.

Now, for the first time, this method has been tested on humans. 16 patients each received two implants; one normal and a similar surface-treated implant as described above. Neither the patient nor the dental surgeon knew which was which. After six months it was noted that for 15 of the 16 patients the treated screw was markedly much better established. Already after two months X-ray images showed positive changes adjacent to the treated screws. No complications occurred.

“It is the first time ever anyone has succeeded in reinforcing the bone around an implant with localised medication”, says Per Aspenberg, professor of orthopaedics, who devised the method of using bisphosphonates in this way.

Pentti Tengvall, professor of biomaterials, developed the method of adhering the drug to the screw and the study was conducted by Jahan Abtahi, specialist MD and PhD, supported by Per Aspenberg. Addbio AB is a Linköping based company now working on commercializing the surface treatment for different types of implants in bone.

Article:
A bisphosphonate-coating improves the fixation of metal implants in human bone. A randomized trial of dental implants by Jahan Abtahi, Pentti Tengvall and Per Aspenberg. The journal ‘Bone’ (in press), published online 10 February 2012.