CHEWING GUM AND CARIES

CHEWING GUM AND CARIES

L E T T E R S practice location is welldocumented,4 as cited in our article. The conclusion that reduced reimbursement rates negatively affect dentis...

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L E T T E R S

practice location is welldocumented,4 as cited in our article. The conclusion that reduced reimbursement rates negatively affect dentists and patients is not speculation, but has strong empirical support.1,5 Larger fee discounts translate into lower earnings for dentists, as demonstrated with empirical support in our article. The increase in patient visits resulting from joining a large discount network does not compensate for the reduced fee levels. This, too, is documented in our article with empirical support. There is often an underlying presumption that patients benefit from dental insurance that unduly reduces reimbursement fees and dentists’ earnings. This is not the case. Patients’ wellbeing depends on a marketplace in which dentists’ earnings are sufficient to ensure that the dental workforce is able to meet patients’ demands for care through sustained practice viability. Since negotiated fee discounts vary from market to market, an important potential effect of very high negotiated fee discounts, over time, is a smaller dental workforce to provide care in those areas than otherwise would exist. L. Jackson Brown, DDS, PhD President L. Jackson Brown Consulting Leesburg, Va.

Albert H. Guay, DMD Chief Policy Advisor American Dental Association Chicago

Donald R. House, PhD President RRC Bryan, Texas 1. House DR. An examination of dentists’ fee discounts prepayment carrier concentrations. Chicago: American Dental Association;

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2005. “www.ada.org/prof/resources/topics/ topics_economic_fee.pdf”. Health Policy Resources Center Dental Health Policy Analysis Series. Accessed March 30, 2009. 2. Johnson T, Owens L. Survey response rate reporting in the professional literature. Paper presented at the 58th Annual Meeting of the American Association for Public Opinion Research, Nashville, May 2003. Section on Survey Research Methods. “www.srl.uic.edu/publist/Conference/ rr_reporting.pdf”. Accessed April 2, 2009. 3. Manning WG, Phelps C. The demand for dental care. Bell J Econ 1979;10(2):503-525. 4. Benham L, Maurizi A, Reder MW. Migration, location and remuneration of medical personnel: physicians and dentists. Rev Econ Stat 1968;50(3):332-347. 5. DeVany AS, House DR, Saving TR. The role of patient time in the pricing of dental services: the fee-provider density relation explained. Southern Econ J 1983;49(3):669-680.

CHEWING GUM AND CARIES

I am writing regarding Dr. Amol Deshpande and Dr. Alejandro Jadad’s December JADA article, “The Impact of Polyol-Containing Chewing Gums on Dental Caries: A Systematic Review of Original Randomized Controlled Trials and Observational Studies” (JADA 2008;139[12]:16021614). The article’s conclusion that “research evidence supports using polyol-containing chewing gum … to prevent dental caries” is not supported. Table 1 reveals that only one study1 rated a perfect Jadad-5. The uncritical acceptance of fatally flawed trials inherent in considering “trials scoring greater than 2 … to be of high quality” represents a grave disservice. A Jadad-3 trial may be nonrandomized, unmasked or lacking in the handling of withdrawals; any of these flaws is sufficient to invalidate the trial results. An unmasked trial, for example, is susceptible to biases that cannot be measured or corrected. It is categorically not possible to deduce what the results would have been had the trial been masked; hence, we are not engaging in causal inference. We simply observe that

the treated patients differed in their outcomes from the control patients, without attributing this observation to the treatments. At least this is what we should be doing. The puzzling willingness on the part of the authors to accept “the old college try” as a valid stand-in for true rigor flies in the face of this prudent caution. For a trial to be of high quality, it would need to be Jadad-5; this is necessary, although certainly not sufficient. The complete failure of the Jadad score has been demonstrated amply by the fact that a Jadad-5 trial later was found to have numerous fatal flaws.2 Its use to evaluate trial quality can best be understood by means of an analogy. We wish to keep invaders out of our building, so we ensure that five doors are locked; however, there are more than five doors, and we do not bother to check the others. Nor, for that matter, do we even bother to check the five doors in question ourselves. Rather, we content ourselves with the claim that they are locked. Similarly here, claims of masking are accepted even when they are not convincing. Randomization is accepted as adequate even when so poor a method as permuted blocks of size two are used. Here, the one Jadad-5 trial1 was cluster-randomized, with the school as the unit of randomization. With five treatments and five schools, there was no true replication; treatment effects are completely confounded with school effects. It is analogous to comparing the weights of males with those of females by selecting one male and one female and weighing

June 2009

Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.

L E T T E R S

each 100 times. As expected, there were significant baseline imbalances across treatment groups (schools) in this one “perfect” trial.1 Could it be that these baseline differences reflected unmeasured differential healthseeking behaviors, a tendency to floss more thoroughly perhaps, that led to the observed differences, and that the gums had nothing to do with them? One cannot enumerate all potential confounders of this sort, so there is no way that we can rule this out, and we must remain in our initial state of uncertainty regarding the impact of polyolcontaining chewing gums on dental caries. We can be certain, however, that none of the trials was very good. Nor, for that matter, was their evaluation. Vance W. Berger, PhD National Cancer Institute and University of Maryland Baltimore County Biometry Research Group National Cancer Institute Bethesda, Md. 1. Machiulskiene V, Nyvad B, Baelum V. Caries preventive effect of sugar-substituted chewing gum. Community Dent Oral Epidemiol 2001;29(4):278-288. 2. Berger VW. Is the Jadad score the proper evaluation of trials? Letter. J Rheumatol 2006;33(8):1710-1711.

Authors’ response: We read Dr. Berger’s letter with interest. We share his concerns about the general limitations of quality assessments of clinical studies.1 However, his comments appear to be a reflection of a limited understanding of the role that the Jadad scale, or any other quality assessment, plays in a systematic review. It is simply impossible for any scale to label a trial as “perfect” or to judge every possible methodological aspect of a study. We regret the way in which 640

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Dr. Berger ignored our efforts to include studies other than randomized controlled trials and to perform sensitivity analyses based on different study attributes. We reported our data transparently.2 In keeping with the spirit that drives the use of systematic reviews to guide healthrelated decisions, we would have preferred a data-driven effort by Dr. Berger to challenge our findings. Sadly, he focused instead on general and wellknown criticisms of quality assessments, missing the opportunity to re-analyze our data and determine whether his opinions actually lead to a different conclusion. Alejandro R. Jadad, MD, DPhil, FRCP(C) Owner, Foresight Links and Chief Innovator and Founder Centre for Global eHealth Innovation and Canada Research Chair in eHealth Innovation and Rose Family Chair in Supportive Care and Professor, Dalla Lana School of Public Health Faculty of Medicine University Health Network and University of Toronto

Amol Deshpande, MD, MBA Consultant, Foresight Links and Consultant, Comprehensive Pain Program University Health Network Toronto 1. Jadad AR, Enkin WM. Randomized Controlled Trials: Questions, Answers and Musings. 2nd ed. London: Blackwell/BMJ Books; 2007. 2. Twetman S. Consistent evidence to support the use of xylitol- and sorbitol-containing chewing gum to prevent dental caries. Evid Based Dent 2009;10(1):10-11.

ACCESS TO CARE

As an active member of organized dentistry for the past 30 years, I have followed the issue

of access to care closely. I found the November JADA trends article1 and commentary2 about Dental Health Aide Therapists (DHATs), Community Dental Health Coordinators (CDHCs) and Oral Preventive Assistants (OPAs) predictable. I have no doubt that any of the above models can work. Politically, that is another story. I also realize the uniqueness of Alaska’s problems. But I am curious about what has happened to another model, started back in the 1960s and proven to work, which still is being used in various locations. That model is the truly expanded-duty dental assistant. Why have we abandoned this method? Space will not allow me to discuss the details of this model but suffice to say I witnessed firsthand, as a student back in the 1970s at the University of Florida, a pilot program using auxiliaries to help address the dental manpower problems that were predicted to occur. Their work compared favorably with our work as dental students and also with the work of dentists in the community. I have little doubt that the DHATs can perform as advertised, but why go down this road? The dental auxiliaries can be trained at a fraction of the cost of DHATs, they fit into our proven team approach to oral health care, and we don’t have to reinvent the wheel. I can think of a slew of ways in both private and public health settings that we can meet the needs of the underserved in a more economically efficient way. For example, a hygienist can administer local anesthetic and then auxiliaries can place and carve restora-

June 2009

Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.