Observations on Current Controversies in Dentistry

Gordon J. Christensen, DDS, MSD, PhD

After several decades practicing, teaching, and doing research in dentistry, I have observed many minor to severe controversies in the profession. Some of them appear to be foolish and irrational, while others are obviously important, influence patient care significantly, and sometimes lead the profession in new directions.

This article identifies several of the current controversies, provides information about each, and shares my personal opinions on each. Undoubtedly, it will irritate some who disagree with my interpretation of the state of the art, which I will try to identify.

This phrase, pioneered by the late American and Canadian physician, Dr. David Sackett, has caused enormous controversy among practitioners and academics since its origin in about 1991. The hierarchy of levels of evidence in dental/medical studies is not well known among dental practitioners, but has become a near religion among academics. They are listed from most to least adequate evidence as follows:

  • Meta-analysis—combines selected research from many studies
  • Systematic review—review of all relevant studies
  • Practice guideline—statement produced by a panel of experts
  • Randomized controlled trial—subjects received randomized clinical interventions
  • Cohort study—follows populations prospectively throughout time
  • Case controlled study—retrospectively follows patients with and without a control
  • Case report—what happened to a patient.

Evidence-based dentistry (EBD) may be the most important controversy that I will discuss. As a teacher of statistics many years ago, I could prove almost anything one wanted to prove by applying various statistical tests to whatever data to prove the desired result. Be careful when reading the results of a study. When considering the so-called “evidence” on any topic, you and I must look deeper than the apparent conclusions to any study, such as: who did the study, who wrote the paper (the author or a ghost writer), who funded the study, when the study was written, are the investigators knowledgeable and clinically competent on the topic, are there some potential ulterior commercial motives for the conclusions, can you believe the statistical analysis, and—very importantly—are the investigators knowledgeable about “real-world” dentistry?

My Observations
One must consider all of the above and other points when interpreting the “evidence” on studies. Every month we, as a team, analyze the “literature” overall to determine on which research projects our organization, Clinicians Report (CR) Foundation, should spend our time, energy, effort, and nonprofit financial resources. Each month, in the hundreds of articles reviewed, there are only a few articles/studies that have logical and proven application to what you and I as clinicians do on a daily basis. In fact, many of the alleged “evidence-based” articles are unfortunately diametrically opposed to what experienced clinicians find in practice.

Figure 1. On the top is an SEM image of a zirconia-based ceramic fixed prosthesis at seating in a CLINICIANS REPORT (TRAC) study. The “evidence” in the literature at that time was very positive about zirconia-based restorations. The lower image shows the same prosthesis in the mouth 8 years later after enough time had elapsed to show that the external ceramic did not match the expansion contraction characteristics of the zirconia. Figure 2. There is no validity to the allegation that articaine causes more paraesthesias than lidocaine. If you are still worried, use articaine only for infiltrations.
Figure 3. Rotary, reciprocal, and hand debridement of root canals have been shown to be equally effective or ineffective. Note the remaining debris in the canal shown here, instrumented meticulously with a rotary file.

Well-planned and executed studies by knowledgeable investigators, who are unbiased, noncommercially supported, and without ulterior motives deserve your attention. However, changes in clinical concepts and techniques should not be done until sufficient time has elapsed to confirm the results of the study by real-world clinical observation (Figure 1).

The remainder of this article includes my conclusions on the printed research on specific topics and the clinical observations that I see as I speak to tens of thousands of dentists annually. I will not list the hundreds of related references, since you, as I, have a computer and access to PubMed, Google Scholar, the Cochrane database of systemic reviews, and your conclusions on any of the topics may be different than mine. I suggest that you attempt to make your own conclusions on the confounded literature on some of these topics.

Articaine is now by far the most used local anesthetic in dentistry. Research concludes that articaine, as currently marketed, is twice as toxic as lidocaine. There have been allegations of more patients having lingering paraesthesia and anesthesia when articaine is used for mandibular blocks versus lidocaine. Studies have not shown that to be true. Also, the observations of practitioners show about the same quantities of paraesthesia with articaine versus lidocaine.

My Observations
The controversy is unfounded. Articaine is twice as toxic as lidocaine. Use half as much anesthetic solution when using articaine. Use infiltrations for most clinical situations. If you are still worried, use only lidocaine for blocks (Figure 2).

Research shows proper use of any of these 3 concepts provides relatively equal results. Rotary is the most popular but breaks the most files. Reciprocal is gaining in popularity because of the frequency of file breakage by some dentists when using rotary devices.

My Observations
This controversy appears to be unfounded. If a practitioner is having success with any of the 3 concepts and is pleased with the long-term clinical results, there is no reason to change. New techniques including high-power ultrasonic debridement of root canals (such as GentleWave [Sonendo]) are coming. This technique may improve the currently relative inability of any of the 3 current techniques to completely remove debris from root canals (Figure 3).

This controversy is a major frustration to me personally. Some research shows the overall success of implants placed by surgical specialists is slightly more successful than implants placed by general dentists. I feel that is to be expected, since specialists usually place more implants and specialists do the studies on success of implants.

As an American Board of Prosthodontics certified prosthodontist and a longtime restorative dentist, I have accomplished implant placement for more than 30 years, taught hundreds of general practitioners (GPs) to place implants, and observed the effectiveness and clinical service of root-form implants as placed by both surgically oriented general dentists and specialists. In my opinion, most surgical specialists know the surgery in more depth, but know little about occlusion or prosthodontics; and, most general dentists know surgery relatively well and have significant knowledge about occlusion and prosthodontics. Each group has weaknesses and strengths.

Figures 4 and 5. An example of a clinical situation in which properly educated general
dentists should remove the tooth and place and restore the implant.
Figure 6. This panoramic radiograph shows gross caries in the impacted second molar. The infection in the pericoronitis and swelling reduced the effect of the local anesthetic. Use of sodium bicarbonate to raise the pH of lidocaine has been long-proven to provide anesthesia, even in the presence of infection.
Figure 7. This is a clenching bruxer with steep canine rise and incisal guidance. Restoration of this person’s condition is diametrically opposed
to restoration of a grinding bruxer, in which case there is usually no lateral or incisal guidance.
Figure 8. The patient had many radiation
and chemotherapy treatments for multiple squamous cell carcinomas in his head. Teeth were removed and healing occurred only after many hyperbaric oxygen treatments. The bottom image shows numerous slightly radiopaque repair restorations done with Ketac Nano (3M ESPE), not amalgam.

A related challenge is that the percentage of Americans who have received implants is low compared to many other developed countries, and even lower than some developing countries. We need to serve more of the public with this life-changing concept by educating more dentists to do them.

My Observations
Surgically oriented, experienced general dentists can be taught in a few days how to successfully place (simple) single implants in healthy patients with adequate bone. I have taught that concept to hundreds of successful general practitioners for 2 decades. It has been estimated that 80% to 90% of implants placed fall into that category (Figures 4 and 5). When general dentists do such dentistry, they soon find some of the more difficult procedures are beyond their comfort zone, and they find themselves referring more than previously to surgical specialists. Who wins? There are 3 winners: the GP, the specialist, and most importantly, the patients. In my opinion, it is high time for manufacturers, GPs, and specialists to eliminate the “turf battles” and educate more dentists regardless of specialty, to better serve more of the American public!

Sodium bicarbonate buffering of lidocaine is used routinely in many areas of medicine to raise the pH of the anesthetic solution, reduce pain of the acidic solution on injection, have faster onset of the anesthesia, and have the anesthesia be more profound in areas of infection. Although these characteristics have been proven by research and observation in numerous areas of medicine, the concept is still used only minimally in dentistry. Onset by Onpharma and Anutra by Anutra Medical provide 2 methods to buffer local anesthetic with sodium bicarbonate. Manual buffering is also used routinely in numerous areas of medicine.

My Observations
Research has shown the positive characteristics of buffering local anesthetics. The reasons for minimal use in dentistry appear to be cost, required changes in clinical techniques, some reported untoward reactions, and satisfaction with current techniques and lack of buffering. In the presence of infection and the related inability to provide adequate anesthetic effect, buffering is a proven solution (Figure 6).

Figure 9. Properly done conservative periodontal treatment has been proven for decades to have the same tooth morbidity and mortality as conventional periodontal surgical treatment, especially in patients such as this 80-year-old. Figure 10. The tongue is a reservoir for the organisms that cause caries and periodontal disease. Cleaning debris from the tongue with a scraper has been shown to be much more thorough than brushing the tongue.
Figure 11. This is a typical patient found in “areas of need.” Hygienists and assistants working under the guidance and supervision of fully educated dentist are very capable of doing many expanded clinical tasks on such patients. Mid-level practitioners are not the type of practitioner needed in areas of need.

We dentists primarily treat 3 major diseases/conditions in our daily practices: dental caries, periodontal disease, and occlusion. However, we do not treat them equally well. Caries is often overtreated, periodontal disease is pathetically undertreated, and occlusion is essentially not treated, except for some orthodontists who primarily treat malocclusion and not the often more serious conditions related to occlusion.

I have taught, researched, and treated the 6 pathologic occlusal conditions for more than 40 years (grinding and clenching bruxism, primary and secondary occlusal trauma, biocorrosive abfractions, and temporomandibular dysfunction). I find the subject in the literature replete with contradictions and highly confounded statements. You can read any conclusions you want from the literature with “evidence” to prove the point of the article. Where are we with this major controversy?

Although so-called “normal” occlusion can be identified and described, there are many variations to the norm within patients who have painless, efficiently functioning occlusion. It has been my experience that personalized occlusion has been developed by each individual patient by that person’s muscle function, tongue movements, the type of food consumed, oral habits, and chewing patterns. Each patient’s occlusion can be quite different from others.

My Observations
To attempt to make rules and overall statements about occlusion that fit every person is futile (Figure 7). To state that one concept of occlusion or one articulator is best for every patient is impossible. As an example, placing a steep, canine-guided occlusion in a mature grinding bruxer is inviting failure and near immediate restoration destruction. Such grinding bruxers need to have their occlusion restored in a modified and refined, relatively flat occlusion similar to the destroyed occlusion. Providing optimal occlusion for patients requires an educated and experienced practitioner to determine the peculiarities of any specific patient, and only then should the sequence of diagnosis and treatment be as follows: carefully analyze and characterize the specific patient’s occlusion; plan the treatment related to those characteristics; and accomplish the treatment, including restorations, occlusal splints, occlusal equilibrations, and any other occlusion modifications as related to those characteristics accordingly.

This controversy has existed my entire career. It is doubtful that it will be solved in the remaining lifetime of anyone reading this article! Some of the research on this subject is highly emotionally charged and in the fringe areas of science. Many diseases and disabling conditions have been allegedly caused by use of amalgam. Conversely, the ADA and other groups continue to support amalgam use. However, the World Health Organization’s official statement is as follows (you may Google the entire document):

The Geneva meeting encourages a global “phasing-down” of the use of dental amalgam and actively supporting the introduction of dental materials alternative to amalgam. A global “phasing-down” of dental amalgam will contribute considerably to reduction of mercury use and release; meanwhile, a complete ban is not yet appropriate. The issue of equity in dental healthcare needs to be carefully considered.

From both the research and clinical observation standpoints, there is no inexpensive alternative to amalgam that lasts as long in moderate- to large-sized intracoronal restorations. Research shows that amalgam in such restorations lasts twice as long as the major alternative, resin-based composite. Composite serves well in small restorations. Therefore, amalgam is still the mainstay restoration in many developing countries and in treatment in low-income treatment facilities.

My Observations
Surveys show that more than 50% of American dentists use amalgam at least some of the time and for specific clinical situations. Many of these dentists claim that amalgam is still the most adequate material for deep box forms and other clinical situations. Yet dentists in numerous other countries use composite, resin-modified glass ionomer, and conventional glass ionomer for all operative dentistry situations (Figure 8). Some of their schools have not taught amalgam in more than a decade. It appears that use or nonuse of amalgam in the United States is a personal decision for individual practitioners. I have found that elimination of amalgam is possible and have not used it for about 20 years. However, my behavior has not been based on the alleged toxicity of amalgam as much as on the patient demand for tooth-colored restorations.

Although some individual periodontists do not fit this statement, I do not see a significant amount of conventional periodontal treatment being accomplished in the United States by GPs or many periodontists, as determined by our CR Foundation surveys. It is the observation of most general dentists that many periodontists are not doing as much conventional periodontal treatment and have replaced that treatment in their business model with implant placement. Can and should dentists involve hygienists more in conservative periodontal treatment for moderate to severe periodontal disease? My answer is a resounding yes! Research on this subject, done at the University of Michigan many years ago, showed that conservative techniques can be as effective as more radical surgical procedures. A conservative estimate of the percentage of these relatively untreated periodontal patients in a general practice is at least 35% of adults. In a typical US general practice, that percentage is at least 400 to 600 patients! Motivated and educated hygienists should be used for this untreated group.

My Observations
Conservative periodontal treatment by dental hygienists is one of the solutions to the great need for treatment of periodontal disease (Figure 9). In my strong opinion, this is a major and important responsibility for dental hygienists —not the often-promoted idea of getting them involved with restorative and other areas of dentistry. Who wins with conservative periodontal treatment? The patient wins most of all, but the practice has a new revenue source, and dental hygienists become more highly involved, motivated, and satisfied. Typical conservative procedures are listed below. The major, most proven procedure is frequent scaling and root planing with less effectiveness observed with some of the other procedures.

  • Education about periodontal disease
  • Frequent oral hygiene instruction
  • Frequent (2- or 3-month) scaling and root planing
  • Tongue cleaning once or twice daily (Figure 10)
  • Alternating oral rinses, changing frequently
  • Subsystemic antibiotics beginning in nonresponding areas 3 months after starting treatment and used for at least 9 months (doxycycline hydrochloride 20 mg, twice per day)
  • Local antibiotics delivered to nonresponding pocket areas after 2 or 3 months of previous points above (most popular is Arestin)
  • Providing the patient with a metal base repairable periodontal removable partial denture, after about 9 months of treatment, allowing easy replacement of teeth, as some may be lost in the future
  • Laser use is still controversial but supported by some groups.

America has a well-defined, effective team of auxiliaries including assistants, hygienists, technicians, administrators, and office personnel. What is lacking? I see nothing. Can the clinical use of these current auxiliaries be expanded? Yes! Mid-level dental practitioners are the strong suggestions of some organizations, allegedly to solve the access to care problem. Would partially educated/trained mid-level practitioners go to “areas of need”? That has not happened to a significant degree in other professions. They want to live in areas of little or no need. By the way, what type of dentistry is present in these “areas of need”? Complex dentistry! What type of practitioner is needed there? You guessed it, fully qualified dentists!

My Observations
The following are just a few of the many techniques that can be delegated to current dental auxiliaries (Figure 11), most of which are legal in all states (check your local practice act for details).

  • Athletic mouthguards
  • Crown try-in
  • Custom tray fabrication
  • Desensitization of teeth
  • Diagnostic data collection
  • Educating patients
  • Fluoride application
  • Laser therapy*
  • Local anesthetic delivery
  • Occlusal splints
  • Periodontal antibiotics
  • Preventive appointment
  • Radiographs
  • Reline denture temporary
  • Restoration placement*
  • Scaling and root planing
  • Snore appliances
  • Sealant placement
  • Whitening teeth in-office
  • Whitening teeth at home

*Not legal in some states.

In my opinion, mid-level dental practitioners are a misguided and potentially dangerous solution for access to care for dentistry, potentially negatively affecting patients, dentists, and the profession at large, and not satisfying the access-to-care problem.

Many controversies are present in dentistry. A few of the major and minor ones are briefly discussed in this article. Dentists are advised to look at the best evidence that is available in the dental literature, blend it with their own and their colleagues’ clinical observations and, only then, use their best judgment on whether (or not) to change their own clinical concepts and techniques.

Dr. Christensen is founder and director of Practical Clinical Courses (PCC), chief executive officer of Clinicians Report (CR) Foundation, and a practicing prosthodontist in Provo, Utah. He is a co-founder of the nonprofit CR Foundation (previously named CRA). Since 1976, the Foundation has conducted research in all areas of dentistry and published the findings to the profession in the well-known CRA Newsletter, now called CLINICIANS REPORT. His degrees include DDS from University of Southern California; MSD from University of Washington; PhD from University of Denver; and 2 honorary doctorates. Early in his career, he helped initiate the University of Kentucky and University of Colorado dental schools and taught at the University of Washington. Currently, he is an adjunct professor at the University of Utah School of Dentistry. He has presented thousands of hours of continuing education globally, made hundreds of educational videos used throughout the world, and published widely. He can be reached at (800) 223-6569 or info@pccdental.com.

Disclosure: Dr. Christensen reports no disclosures.