Follow Marin Events

• Home • Up • The Junk Science of Fluoride-Free Water • more fillings than you need •
•  •

In the study, patients in the experimental group with early decay received a fluoride varnish to the site. Dentists also gave those patients fluoride varnish preventively two to four times a year, and encouraged them to brush well and avoid sugary snacks between meals.

Tooth decay, or caries, is caused by bacteria that thrive on sugars in the mouth and produce acids. Left in contact with a tooth, the acids draw out minerals, creating microscopic pores. Decay progresses slowly, and it may take years for a full-blown hole, or cavity, to form; until that point, it can still be reversed. Mineral-containing saliva is constantly working to replenish the teeth, and fluoride aids remineralization.

After a filling, more than 60% of people will return to the dentist with new decay within the next two years, says John Featherstone, dean at the University of California, San Francisco, School of Dentistry. “Two-thirds of the population. That’s huge,” Dr. Featherstone says. “So you need to build into the treatment plan a therapeutic regimen.” He says dentistry’s traditional drill-and-fill response to tooth decay is similar to a doctor who, upon seeing a patient with a red, swollen arm, recommends cutting the arm off.

Among other treatments to arrest tooth decay that researchers have investigated is Xylitol ₁, a natural sweetener used in some candies that has been shown to help prevent bacteria from making the acids that cause tooth decay. Prescription antibacterial rinses seem to help but need further study, researchers say. For biting surfaces prone to decay, plastic sealants applied by a dentist prevent nutrients that would feed bacteria from getting into grooves on tooth surfaces.

The advantages of fewer fillings go beyond avoiding the dreaded anesthetic injection and drill. Fillings don’t last forever and eventually need to be replaced, says Mark Wolff, chair of cariology at New York University College of Dentistry. Each successive filling is going to be bigger than the last, progressively weakening the tooth. “The key is avoiding the first one,” he says.

Dr. Wolff recalls a time his two children came home from college, one with four areas of decay and the other with one. “I looked at the X-rays and was quite horrified,” he says. “They’d gone off to college with not the slightest evidence of decay. We put them on fluoride, a calcium-containing toothpaste, and Xylitol,” he says, and the teeth remineralized over the next two years. “Neither of my children have any fillings,” he says.

An excessive amount of fluoride is toxic, but research has shown that in the amounts used in dentistry and found in water supplies, fluoride is safe and helps prevent cavities, Dr. Wolff says.

There is a substantial body of research supporting remineralization as a treatment for early tooth decay, and little opposition in the dental profession, says Margherita Fontana, a professor of cariology at the University of Michigan School of Dentistry. Tradition, however, has been an obstacle to widespread use of the treatment. “For older generations [of dentists], it just feels wrong to leave decay and not remove it,” Dr. Fontana says. “That’s how they were trained.”

Reimbursement is another obstacle. Insurance typically covers application of fluoride varnish in children, but not adults. The cost ranges from $25 to $55, according to the American Dental Association’s Health Policy Institute. Other preventive treatments also generally aren’t covered.

Dr. Featherstone says he advises patients at high risk for decay to seek preventive treatment. “For $100 a year you can have the therapy and save yourself a crown for $1,000,” he says. Over-the-counter fluoride rinses also provide some benefit. “If you have new decay every so often, you’re high risk, it’s as simple as that,” says Dr. Featherstone. According to the National Institutes of Health, 20% of the U.S. population gets 60% of all caries.

In a study, Dr. Featherstone and two colleagues, Benjamin Chaffee and Jing Cheng, looked at the effectiveness of nonsurgical therapies for tooth decay in a retrospective analysis of more than 2,700 patients’ records at the dental clinic at UC, San Francisco. All patients were at high risk for tooth decay.

The findings, published in September in the journal BMC Oral Health, showed patients who took home anti-caries agents at two or more dental visits had 20% to 40% fewer new decayed teeth over 18 months.

Dr. Featherstone led a randomized clinical trial of 231 adults, with about half of them treated by dentists prescribing both antibacterial and fluoride treatments for any tooth decay before a cavity had formed. The rest of the patients were treated by dentists who continued their usual care. The need for fillings after two years in the new treatment group was 24% less than in the regular-treatment group, according to the study, published in 2012 in the journal Caries Research.

_{1 Some research concludes thta XYLITROL simply allows the saliva to circulate with the associated chewing.}

Will Dentists help you grow new teeth? BBC Tiffanie Wen 22 September 2016

APPROACHES

1. We may never evolve to grow a third set of teeth, but that hasn’t stopped scientists from attempting to find a way to replace extracted teeth with new, live replacements. One lab at King’s College London has successfully implanted bio-teeth into mice. Using gum tissue from humans and tooth forming cells in mice, they were able to grow teeth with dentin and enamel in mice. “What’s incredible is that the researchers can implant this developing tooth germ and it’s able to re-orientate itself to form and recruit blood vessels from surrounding tissue to make a live tooth,” Tucker says.
   One of the challenges of using the therapy in humans, she says, comes from culturing stem cells in-vitro, which tends to make them lose their potency.
2. Other recent approaches have focused on finding ways to get our teeth to heal themselves. Ruchi Sahota, a dentist in California and a spokesperson for the American Dental Association, suggests visualising the anatomy of a tooth like an apple. “They have a thin enamel shell, like the skin of an apple, that protects the inner core, which is the dentin of the tooth. And just like the seeds of an apple, we have the nerve of our tooth,” she said. “A cavity tends to form in the enamel. When it gets into the dentin, you need to fill it at the dentist. When it gets to the nerve, that’s when you need a root canal.”
   • A company called Reminova is already working to bring a new approach to market. Also based on research at King’s College London, the technique uses painless electric currents to encourage re-mineralisation of the enamel healing tooth decay at the earliest signs of decay.
   • Other approaches use the cells that are in our teeth to heal cavities that have already penetrated  the enamel, by stimulating the creation of dentin, the calcified tissue that makes up the inner portion of our teeth. Recent research published in the journal Science Translational Medicine for example, found that treating exposed tooth pulp in rats with low-power laser light before filling the cavity could induce stem cells to create dentin in the tooth.
   • In another approach, researchers from the University of Nottingham and Harvard University are developing a therapeutic biomaterial that can work to heal a cavity, and intervene before a root canal is necessary. The material can stimulate a particular type of stem cells in the pulp tissue to interact with other material that forms a new kind of dentin-producing cell.  
     “This material can be injected in contact with pulp tissue and hardened with UV light to form a plastic,” says Adam Celiz, a postdoctoral fellow that is working on its development. “The native cells interact with the plastic and differentiate into a different kind of cell that produces dentin. So we’re hoping to restore that dentin layer to return vitality to the tooth, which means the pulp tissue wouldn’t have to be removed by a root canal.”

==================================================================================

Researchers discover new natural tooth repair method using Alzheimer's drug Published on January 9, 2017 · source A new method of stimulating the renewal of living stem cells in tooth pulp using an Alzheimer's drug has been discovered by a team of researchers at King's College London. Following trauma or an infection, the inner, soft pulp of a tooth can become exposed and infected. In order to protect the tooth from infection, a thin band of dentine is naturally produced and this seals the tooth pulp, but it is insufficient to effectively repair large cavities.

Currently dentists use man-made cements or fillings, such as calcium and silicon-based products, to treat these larger cavities and fill holes in teeth. This cement remains in the tooth and fails to disintegrate, meaning that the normal mineral level of the tooth is never completely restored. However, in a paper published today in Scientific Reports, scientists from the Dental Institute at King's College London have proven a way to stimulate the stem cells contained in the pulp of the tooth and generate new dentine - the mineralised material that protects the tooth - in large cavities, potentially reducing the need for fillings or cements. The novel, biological approach could see teeth use their natural ability to repair large cavities rather than using cements or fillings, which are prone to infections and often need replacing a number of times. Indeed when fillings fail or infection occurs, dentists have to remove and fill an area that is larger than what is affected, and after multiple treatments the tooth may eventually need to be extracted. As this new method encourages natural tooth repair, it could eliminate all of these issues, providing a more natural solution for patients. Significantly, one of the small molecules used by the team to stimulate the renewal of the stem cells included Tideglusib, which has previously been used in clinical trials to treat neurological disorders including Alzheimer's disease. This presents a real opportunity to fast-track the treatment into practice. Using biodegradable collagen sponges to deliver the treatment, the team applied low doses of small molecule glycogen synthase kinase (GSK-3) to the tooth. They found that the sponge degraded over time and that new dentine replaced it, leading to complete, natural repair. Collagen sponges are commercially-available and clinically-approved, again adding to the potential of the treatment's swift pick-up and use in dental clinics. Lead author of the study, Professor Paul Sharpe from King's College London said: "The simplicity of our approach makes it ideal as a clinical dental product for the natural treatment of large cavities, by providing both pulp protection and restoring dentine. "In addition, using a drug that has already been tested in clinical trials for Alzheimer's disease provides a real opportunity to get this dental treatment quickly into clinics."

Cavity Prevention is key

Of course, dentists will tell you that preventing cavities from forming in the first place is the key to your dental longevity, starting with good oral hygiene—brushing twice a day with fluoridated toothpaste, flossing once a day and making regular trips to the dentist – and eating the right kind of foods.

“The most important food and thing for us to keep in mind in terms of prevention is water – especially fluoridated water,” says Sahota. “Not only does the fluoride help mineralise and regenerate tooth structures that may have become infected by a cavity, the physical motion of drinking water helps to flush away food, bacteria and any debris that may be stuck in your teeth as well.” She adds that dairy is also great because it’s high in calcium and that lean protein helps strengthen and rebuild enamel.

Even if we can rebuild this material in our mouths, we still have to fend off a modern menace in our industrialised diets – refined sugar.  That’s because bacteria secrete acid when it breaks sugar down, and that acid can cause decay in our teeth.

So what type of candy is best avoided? Sahota says hard candies like lollipops are especially bad since they give you a constant exposure to sugar, while sticky candies get stuck in your teeth for long periods of time.

At least she has good news for the chocoholics among us. “Chocolate after lunch or dinner is a better choice than a lot of other candy because it can get flushed out more easily. So go ahead and enjoy a bite after your meal.”

_{==================================}

_{Mammal's Teeth}

If you don’t like going to the dentist, you’re not alone. Most people have some anxiety about visiting the dentist, with one study in the Netherlands indicating that 24% of adults feared the dentist. Moreover, significant amounts of people who fear the dentist avoid visiting until they really need to. That could help explain why 92% of American adults have tooth decay in their permanent teeth.

But there is good news on the horizon as well—recent research also suggests that we might soon be able to refill the holes in our teeth with healthy, living tissue, giving our permanent teeth a second chance.

Compared to other species, you may think we humans are extraordinarily unlucky to have to depend on the same set of adult teeth for the majority of our life. Shark enthusiasts are familiar with the fact that sharks have unlimited sets of teeth during their lifetimes. Galeophobes in particular might be terrified to learn that sharks have rows of baby teeth underneath the skin waiting to replace the functional ones, and shed and replace teeth as often as every three weeks, causing experts to believe that the sea floor is littered with the teeth of sharks.

So if sharks, and most reptiles and amphibians can replace their teeth over a lifetime, why do humans and most mammals only get two sets of teeth?

Abigail Tucker, a professor of development and evolution at King’s College London says that there is a trade-off between the complexity of the teeth and the amount of sets the species gets. Since mammals have the ability to chew, meaning they can grind their teeth sideways (think of the movement a cow or horse makes) we have developed complex sets of teeth with multiple cusps, the bumps and mounds that define the shape of our teeth. While our pointy canine teeth (cuspids) each have only one cusp, our premolars (bicuspids) each have two cusps and our molars each have four or five cusps.

“The complexity is linked to diet, with bamboo eaters having the most complex teeth,” she says. “Something like a giant panda or a bamboo eating lemur have complex back teeth with lots of cusps so they can really chew and grind the hard tissue. So their teeth look similar even though they’re completely unrelated to [other] mammals.”

There are other fascinating examples of animals with unique dental abilities. Piranhas have teeth that are fused together to make large teeth that resemble a type of sharp knife. When they shed teeth, they lose an entire quadrant all at once, and rely on the other three quadrants to survive while the new teeth come in.

While mammals are typically restricted to two sets of teeth – a set of deciduous teeth and a set of permanent teeth – some mammals have retained the ability to create more teeth or have evolved to have the ability again. Manatees for example keep forming new teeth in the back their mouths over the course of their entire lives. 

Other animals only get one set of teeth, but they continuously grow, including the aye aye lemur and rodents like rats and mice. “Rodents and rabbits typically have a stem cell population at the base of the tooth that keeps growing dentin and enamel. It’s an adaptation to the hard foods that they’re eating,” says Tucker.

It’s unlikely that humans will ever evolve to have more than two sets of teeth, since evolution requires that differences influence whether or not offspring survive. But it is true that we are still evolving in a way – experts believe that fewer and fewer people are now getting wisdom teeth, the third molars that arrive in early adulthood, when our jaw is fully grown. “We’re cooking our food and it’s more tender so there’s no need to have the third molar. In addition, our jaws are getting smaller so there’s less space,” Tucker says. “Because of that we’re seeing a higher percentage of people who are missing their third molars. About 20% of the population doesn’t have wisdom teeth.”