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Inside Dentistry
October 2018
Volume 14, Issue 10

One Small Step

Dentistry inches closer to a moonshot to eliminate dental caries

David C. Alexander, BDS, MSc, DDPH

At first glance, the issue of dental caries prevention and treatment is not particularly inspiring. It's not a popular topic in top-of-the-line CE programs, and although there is a steady stream of research and new product claims that prefigure a caries-free future at some indeterminate point in time, these discoveries are not yet available to the practitioner or the patient. Until they are, the people on the ground who share a strong concern for their patients and their broader communities are working with the available technologies while devising and implementing adjunct strategies to approach this disease from all angles. These strategies include patient education and public advocacy to modify behavior, sugar taxes and nutritional counseling to reduce risk, access to care and caregiver accountability to deliver appropriate procedures, and other innovative approaches, at both the individual and global level, that collectively aim toward an oral health moonshot to realize a caries-free future.

For the general dentist working in a shifting healthcare environment, caries prevention is a crucial part of the evolving oral-systemic, medical model of dental care. From this perspective, what are the strategies, both big and small, that ambitious oral healthcare practitioners are implementing in their circles, and how can they combine their efforts to truly achieve liftoff and realize this important mission?

Reframing the Problem

Unfortunately, the opinion of much of the patient and caregiver population is that caries are an inevitable result of our diets or genetics that can be easily treated with a trip to the dentist. The recognition of dental caries as a serious, chronic, widespread health condition has not penetrated mainstream society. Campaigns to educate people about the importance of oral health and caring for their mouths are in relatively early stages and do not seem to be as effective as programs for other conditions. Many individuals in the United States are only a generation removed from the population who believed that edentulism and dentures were an unavoidable aspect of aging. With so many other serious and deadly health conditions to address, why should resources be channeled to combat this disease?

"I think caries has always been the ugly step child," says Andrea Zandoná, DDS, MSD, PhD, an associate professor in the Department of Operative Dentistry at University of North Carolina. "When fluoride proved successful, people thought, ‘good, caries will no longer be an issue.' Then the attention (and with it, the funding) shifted to the next problem, which was periodontal disease and oral-systemic relationships. Unfortunately, to this day, dental caries remains the most prevalent disease of childhood. So we need to do better."

For example, The European Organisation for Caries Research (ORCA) promotes scientific research and a cariology curriculum. Mark Wolff, DDS, PhD, the Morton Amsterdam Dean at the University of Pennsylvania School of Dental Medicine, notes that "in the United States, there are societies for periodontal and endodontic diseases, but until the recent formation of the American Academy of Cariology, there were none for caries, which is more prevalent." To reduce tooth decay, he believes, there needs to be an interface among researchers, educators, third-party payers, governmental organizations, and other stakeholders to advance the idea that caries is a disease-like diabetes or Parkinson's-and spur the necessary activity.

The medical management of caries, as opposed to surgical, is gaining traction as a concept in synchronicity with other rapid changes in healthcare delivery. Adapting the model of chronic disease management (ie, an integrated care approach that includes screenings, examinations, risk assessment, monitoring, coordinated treatment, and patient education to improve quality of life while reducing healthcare costs) to dental caries is another way to address this situation. As Vineet Dhar, BDS, MDS, PhD, clinical professor and chair of orthodontics and pediatric dentistry at the University of Maryland School of Dentistry, explains, "Unless we begin to manage dental caries in a way that is similar to other chronic diseases, the disease process will continue. The traditional restoration of a carious lesion merely treats the manifestation/symptoms of the disease and not its cause. Therefore, it is equally important to devise strategies that can produce an oral environment conducive to the reestablishment of a stable biofilm, thereby lowering a patient's risk of developing new caries."

A Multifactorial Puzzle

Our understanding of the etiology and pathophysiology of caries is constantly evolving, and there has been a recent surge in research exploring the multifactorial nature of the disease, Dhar adds. "Simplistically speaking, in a caries-free individual, we expect to find a diverse, stable oral microflora. Several bacteria have been identified as having caries-producing potential, and studies are addressing how they function together rather than individually. Everyone's oral biofilm is unique, and some individuals are more resilient to stressors than others."

"Previously, theories about caries could not be proven or disproven because scientists didn't have the ability to test them in the laboratory," says Joel Berg, DDS, MS, professor, University of Washington School of Dentistry. "With new tools, we can better understand the more than 500 bacteria present in the mouth, their interactions among each other and with the host, and what biochemical signaling is occurring to turn acid production on after sugar exposure-or what is turning it off. Once those pathways are identified, perhaps more targeted pharmacologic development can occur."

Unfortunately, Zandoná admits, a significant amount of valuable research on cariology simply does not reach the general dentist because it is less likely to be published in the journals that they read regularly. "I'm always surprised when I speak at a meeting, and I find that only a few people have heard of the changes in the field of cariology based on current research. It's not as well-disseminated as we may think."

Diagnostic and Risk Assessment Strategies

If caries is to be treated as a chronic disease, then the population needs to be differentiated into risk levels. "We've never done that," Berg says. "We've acted as if everybody possesses the same level of risk, even though we know that's not true, scientifically. This is largely because we haven't had the validated tools to conduct appropriate risk assessment. That's the crucial missing piece."

In addition to caries management by risk assessment (CAMBRA), other risk assessment tools are available from the American Academy of Pediatric Dentistry and the American Dental Association. "The issue is that they're not specific enough. They still can't single out the one patient who will have the problem," Berg notes. Even so, he adds, elements of those tool kits can be useful. "Caries is a behavioral disease, so having a conversation around those elements may help reduce a patient's risk. But without a specific test, it's hard to determine whether your actions really lowered the risk or not."

Regarding the use of available adjunctive technology for caries detection, false positives and the potential for overtreatment remain issues for clinicians, Zandoná says. "With some of these devices, you end up detecting more early caries lesions, which should concern cariologists who are trying to implement new technology into clinical practice due to the potential for increased surgical interventions for lesions that only require preventive (ie, non-surgical) intervention."

Zandoná believes that dentists should be better trained to perform a thorough visual examination. "I think this is still the best diagnostic tool that we have. Today, most dentists are using loupes, and with better training regarding visual assessment, the disease process, and response to management interventions, they will be able to provide optimal preventive care. In my opinion, there is no single device that is going to be able to detect and assess caries activity on all surfaces with the same level of sensitivity and specificity across the board."

Still, adjunctive diagnostic and assessment technologies have a definite role in many practices. Susan Vogell, RDH, MBA, associate professor at Farmingdale State College, Farmingdale, New York, explains that her dental hygiene students are trained in the use of caries detection technologies such as transillumination and fluorescence. "Knowing how to use these methods is an important part of their education because, down the road, these technologies will improve and qualify for reimbursement. It's cheaper for insurance companies to help us prevent the disease than it is to help us restore it."

Another diagnostic pathway that is gaining ground is saliva testing. "For a long time, there was a push to test for Streptococcus mutans," Vogell says. "However, we now know it's not just the S. mutans-there are many other bacteria that come into play. Regardless, I'd like to see more chairside testing of saliva. It would be a great educational tool that patients would respond to. We need to do a better job of highlighting the oral-systemic connection for the public."

"Saliva is an indicator of oral health, so it behooves dentists to start testing it, at least at a simple level, such as calibrating flow rates for patients," Berg adds. "As we move into risk-based management, these tests are going to become more important in every practice."

Minimally Invasive Mindset

As caries is detected earlier and its pathophysiology is better understood, how can this knowledge be leveraged to achieve better patient outcomes? How can it be used to arrest the disease, retain tooth structure, and even remineralize the lesions?

"Unfortunately, in my opinion, the concept of minimal intervention dentistry has been very successful in the dental schools, but less successful in real world practice," Vogell notes. "Our society is highly litigious. When you ask dentists why they are intervening for caries barely at the dentin, rather than trying to remineralize it, the concern is that the patient might return with a larger lesion, making the clinician responsible."

Furthermore, the compensation system for dental treatment does not support minimally invasive approaches. "This is crucial: we have to drive the incentives toward minimal-not maximal-intervention," Berg says.

Instead of performing operative work with a bur, the goal is to manage these lesions in a different way, notes Augusto Robles, DDS, MS, assistant professor and director of the operative dentistry curriculum at the University of Alabama at Birmingham School of Dentistry. "For example, products are being developed that separate the teeth in the same manner as we do before putting braces on patients. That separation provides a window of opportunity to make clinical observations about what is going on between the teeth. If the surfaces are not cavitated, it also offers the opportunity to infiltrate resin or apply a medicament, such as silver diammine fluoride (SDF) or fluoride varnish. The point is to prevent the need to grind away healthy tooth structure."

Theodore P. Croll, DDS, who maintains a private pediatric dentistry practice in Doylestown, Pennsylvania, and has faculty affiliations with the University of Washington, Seattle, and the University of Texas, San Antonio, has been exploring various treatment options for decades, beginning with resin infiltration. "Basically, you're intercepting the decalcification of an axial surface region of enamel," he explains. "When there's no obvious penetration of the disease into dentin, you can roughen the surface, etch it, then infiltrate and harden a resin material, which does not decalcify. I call this "micro-restorative dentistry" and, more specifically, a "smooth surface ssealant."

Robles elaborates that "the acid cleans up any debris and creates high surface energy, which makes the enamel thirsty for the resin. Then you use alcohol to help dry the area. Finally, the resin is applied for 3 minutes, and it remains there. The idea is that the thirsty enamel immediately soaks up the resin to a depth of up to 100 microns, creating a seal on the outer surface."

For specific cases, glass ionomers are another valuable but underutilized option, according to Vogell. "I'm looking to implement them more in our clinic. They're less technique sensitive, and can be useful in patients for whom it is difficult to achieve isolation, such as individuals who have developmental disabilities."

In Croll's experience, even though glass-ionomer systems have markedly advanced, they have not demonstrated the fracture strength and wear/erosion resistance of resin-based composites. On the other hand, due to their biocompatibility, fluoride content, hydrophilicity, and chemical bond to dentin, glass ionomers are a better dentin replacement material. "It became apparent that we should be doing biomimetic, tissue-specific tooth repair, wherein the glass ionomer systems would replace the dentin and the resin-based composites would replace the enamel," he explains. "With the development of resin-modified glass ionomers, the materials are able to bond to each other through their resin components and simulate natural dentin/enamel anatomical construction.

Since 2014, for primary teeth, Croll has been using a dental restorative product that combines a bioactive resin component with reactive glass fillers. For deep caries penetration, for either primary or permanent teeth, he uses a calcium silicate/MTA liner material that has a photopolymerizable resin component. This material does not break down like certain calcium hydroxide products, is biocompatible, and facilitates pulp healing.

Any discussion of caries eventually turns toward the recent growing interest in SDF for tooth sensitivity and as a caries "attenuation"agent.  Despite its chief disadvantage of staining caries lesions black, SDF clearly has multiple purposes for use in carious primary teeth as well as indications for use in the permanent dentition. Nathaniel Lawson, DMD, PhD, director of the Division of Biomaterials at the University of Alabama at Birmingham School of Dentistry, says, "This is one of the challenges associated with using SDF. We need to figure out where practicing dentists find a place for a liquid that turns patients' cavities black. For children whose primary teeth will be shed, it makes sense. And for elderly patients, particularly those in continuing care facilities, it is great for root caries. But it can also fit into the average general dental practice. For example, for patients who have rampant caries and can't afford the time or expense to get all of the needed restorations done, arresting lesions with SDF in the interim is a good service."

Highlighting the need for adult caries treatment is an important aspect of acquiring the necessary resources to fight the disease. Diseases that only affect children never get enough attention, Berg explains. "However, there's a lot of attention placed on seniors because most legislators are in that age group and they can relate. As root caries affects more of the older population, better products and systems are going to be developed that will benefit patients of all ages."

Prevention in the Real World

The bottom line is that practitioners cannot be present to monitor their patients' food and drink choices, home hygiene practices, or compliance with dental products and appliances. Further complicating home hygiene efforts is the fact that some patients have no autonomy; their oral care is dependent on caregivers, either professional or familial. Other patients would seek additional care, but have no access because of financial or other constraints, such as transportation. To address these real-world issues, oral healthcare practices are upping their game by incorporating more effective patient education and nutritional counseling, hygiene product recommendations, collaborative care that enlists the expertise of other health professionals, risk-based recall intervals, and other creative approaches, such as using digital and mobile technologies to deliver care instructions.

"We teach our dental hygiene students to do two things with their patients. First, they generate a CAMBRA score to determine risk," says Vogell. "Then they educate patients based on that. Patients supply us with a food journal, and we discuss their daily sugar intake and its effect on their oral as well as overall health. I believe that all dental hygienists and professionals should provide nutritional counseling, because after we bring down the bacteria level in their mouths for the day, they are on their own."

Years ago, Vogell adds, hygienists would recommend fluoride. That was all they had to offer. "Now, the dental product aisle can be overwhelming for a patient. There are so many choices. Students need to know about all these options to help patients decide for themselves what is best. If patients are opposed to fluoride, we first attempt to educate them about its benefits. If they're still opposed after this, we're ready to suggest other options that could complement their home care. We always try to offer patients some type of home therapy to remineralize lesions, but compliance is often problematic. Do patients want to know how much these products cost before they make their decision to try? They do, and sometimes that makes the decision for them."

Many patients simply cannot access dental care, even though they recognize its importance. Elisa Ghezzi, DDS, PhD, adjunct clinical assistant professor at the University of Michigan School of Dentistry, says, "I've witnessed a lot of frustration in groups that are trying to get care for patients. Those outside the dental profession are not addressing oral health because they have no solution for it. Agencies on aging that are trying to connect seniors to resources say it's very difficult to find places where these individuals can receive treatment. For example, these patients often need to be transported. Most of us in dentistry don't have the resources, nor do we feel we have the obligation to arrange patient transportation. However, we could be collaborating with those who know where those resources are, such as local agencies on aging."

It often comes back to the compensation, Berg says. "Most dentists would love to manage health, but we only get compensated for treating disease. Therefore, changes in this regard are essential to improve health patterns-they go hand in hand."

Other than the insurance companies, the major participants with financial resources to influence oral health are the manufacturers of consumer products. "I think we shouldn't underestimate the power of consumer advertising," Berg says. "Look at the expenditures related to major products like mouthwash. Hundreds of millions of dollars are spent on advertisements talking about plaque, gingivitis, and bad breath. More recently, they've added the benefits of caries prevention to their marketing. When advertising advises consumers about behavioral change, in some ways, it's raising patient literacy related to caries and oral health, which is critical."

Individuals in some population groups prefer to get their healthcare information from their society or community, rather than trusting a health professional, Vogell explains. "This could also be related to diversity in the healthcare sector. People want to obtain their information from someone who looks like them, speaks their language, and most likely respects them. Regardless of culture, people don't want to have an authoritative dental clinician attack them about what they're not doing. They want to be brought into the conversation."

Edentulism is not inevitable, and people intend to keep their teeth. "But we aren't educating them and providing them with enough preventive opportunities," Ghezzi says. "Our job is to diagnose their conditions and let them know what they need to do to keep their teeth. Now, whether they decide to follow our recommendations or not is up to them. Unfortunately, we sometimes have to tell them things that they don't want to hear, and ask them to decide: do you want your teeth or not?"

Part of imparting patients with both better information and increased control will likely include the adoption of personal health technology, an area that is rapidly advancing. "Smartphones and social media can show us how we are doing compared with everybody else," Berg says. "I can tell you how many steps I've taken relative to everybody my age in my zip code today, but I can't tell you how my gingivitis compares. Most people are competitive. We could improve health literacy, self-motivation, and prevention efforts by providing more global access to de-identified data. In this manner, patients could see how they are doing compared to others. An exciting opportunity exists for someone to create an integrated app that lets people know that they're getting healthier through self-empowerment."

Conclusion

"We know that caries is a behavioral disease; yet historically, we've acted as if that's not the case and patients have no power over their own situations whatsoever," says Berg. "The reality is that they have all of the responsibility and all of the control-they just don't have all of the knowledge."

Although we may never realize a true cure for dental caries, as our understanding of the disease progresses, taking the "small steps" of empowering patients with all of the knowledge necessary to protect themselves and leveraging the ongoing scientific advances into useful diagnostic and treatment modalities are sure to result in a "giant leap" in the reduction of dental disease.

Where Is the Caries Vaccine?

Discussion surrounding creation of a vaccine for caries surfaces periodically. However, according to Dhar, considering the multifactorial nature of chronic diseases, the development of a vaccine is still far from reality, and therefore its potential impact, if any, on the disease process is indeterminable. Berg notes that there has been some interesting work, "particularly at a time when we thought that caries was exclusively caused by S. mutans and related bacteria, but even then, it was complicated, especially when it reached the point of a clinical trial." As an example, Berg cites using genetically modified bacteria. "Scientifically, it may have been an interesting idea, but are parents going to allow their kids to be injected with genetically modified bacteria to treat caries when they are often opposed to this practice for conditions associated with greater morbidity and mortality?"

A further challenge to vaccine development is the complexity of the biofilm and the interaction between bacteria. "If you get vaccinated for measles, you're not going to get measles," Berg says. "It's almost 100% successful. But that will never be true with a caries vaccine because the disease process is more complex. Caries is not an antibody response to a virus, it's a condition involving a complex biofilm and host dynamics, including sugar consumption, salivary flow, and other factors. I believe that we are going to see more development in the area of targeted pharmaceuticals that aren't vaccines, such as ones designed to interfere with biochemical pathways to prevent the signaling that causes the acid production."

"I think that we're moving away from the idea of a vaccine for a number of reasons," Wolff concurs. "Whether or not we can actually target individual organisms to achieve a reduction in decay is a significant question. That being the case, our attention has moved to probiotics, prebiotics, and customized medicine-developed either from the patient's DNA or the DNA of the biome. Efforts in these directions are likely to progress much more easily than a vaccine."

A plaque detection probe has been designed that works in conjunction with common x-ray technology to locate S. mutans in a complex biofilm network. In a recent study, researchers demonstrated the probe's ability to efficiently identify biochemical markers present at the surface of the bacterial biofilm and simultaneously destroy S. mutans.

Source: University of Illinois College of Engineering (August 2018)

Latest Research Announcements

Researchers have developed a new way to grow mineralized materials that could be used to regenerate hard tissues such as dental enamel. The method's mechanism is based on a specific protein-based material that is able to trigger and guide the growth of apatite nanocrystals at multiple scales.

Source: Queen Mary University of London (June 2018)

A bioinspired repair process has been developed to restore the mineral structure found in natural tooth enamel. The researchers accomplished this by capturing the essence of amelogenin-a protein crucial in the formation of hard crown enamel-to design amelogenin-derived peptides that biomineralize.

Source: University of Washington (April 2018)

According to the results of a recent study, twice-daily rinses with FDA-approved nanoparticles can break apart oral biofilms and prevent tooth decay. The nanoparticles break apart dental plaque through a unique pH-activated antibiofilm mechanism.

Source: University of Pennsylvania School of Dental Medicine (July 2018)

An imaging system has been developed using a unique bioluminescent recombinant photoprotein that reacts with free calcium ions released from demineralizing tooth surfaces to enable the early detection of active demineralization caused by caries or erosion. This specialized device applies the protein to the tooth surface and simultaneously images the resulting bioluminescent reaction.

Source: Calcivis (2017)

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