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RESEARCH REPORT |
1 Department of Conservative Dentistry, University of Heidelberg, Im Neuenheimer Feld 400, D-61920 Heidelberg, Germany;
* corresponding author, hansjoerg.staehle{at}med.uni-heidelberg.de
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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KEY WORDS: diagnostic tests • reproducibility of results • double-blind method • applied kinesiology • complementary therapies.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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The validity of AK has been critically reviewed in the literature (Schissel and Dodes, 1997). For example, the ability of allergies and/or nutrition incompatibilities to be diagnosed by means of AK has been seriously questioned (Kenney et al., 1988; Lüdtke et al., 2001; Teuber and Porch-Curren, 2003). Nonetheless, this procedure is still used by some dentists to test their patients’ tolerance of certain dental materials, although no controlled studies addressing the test-retest reliability of AK are available thus far.
It was therefore the objective of the present study to test the hypothesis that the ability of AK to make a consistent statement about the (in)tolerance of a dental material is not significantly greater than what would be expected by chance alone (e.g., by tossing a coin). The alternative hypothesis contended that a significantly higher reliability could be achieved by using the AK test as compared with random probability.
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MATERIALS & METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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A total of 112 volunteers (65 females and 47 males) participated in the investigation. AK testing was performed by two dentists experienced in the diagnosis and treatment of "intolerance to dental materials". Both dentists had earned the medical diploma ("Ärztediplom") of the International Medical Society for Applied Kinesiology (IMAK), including 160 hours of supervised training (for further details, see http://www.applied-kinesiology.com>). The principal investigator (H.S.) did not impose any restrictions regarding the selection of individuals to be tested. Instead, the two AK dentists could freely decide which test persons appeared to be suitable for inclusion in the study. They were also allowed to arrange the exterior conditions of the investigation according to their needs (well-circulated testing rooms with windows; adjustable chairs; no artificial light beams, such as neon light, flashing into the eyes of the test persons). The study participants were informed about the procedure and the purpose of the investigation, and gave their informed consent according to the criteria of the Ethical Committee of the Medical Faculty of the University of Heidelberg.
Eight to 14 days before being tested, the participants received a sample of both test materials, as required by the AK dentists. In addition, they were instructed to keep the materials in their mouths once for 30 min and to swallow the accumulating saliva. This was done to ensure that all persons had established contact with the materials before the actual testing began.
Before the start of the investigation, the participants had to comply with the following instructions, given by the two AK dentists: They were not allowed to wear watches, jewelry, rings, and/or piercing, or to carry cellular phones during the test procedure. They also had to give information on any scars anywhere on their bodies (potential criterion of exclusion from testing, decided by the AK dentists). From 2 hrs before being tested, subjects were forbidden to drink coffee, herbal tea, or black tea, or to eat. Immediately before the start of the investigation, the participants were asked to drink a glass of tap water (250 mL).
Each study participant was personally welcomed by the examining dentist. He or she was then questioned for any "particularities" (such as past accidents and scar formations). The participants were informed about the test procedure. Thereafter, each subject underwent a kinesiologic pre-screening (such as testing of "correct" muscular reactions after pre-testing of normal muscular tone, as defined by the AK dentists). Based on these pre-tests, it was decided whether a test person was eligible for further testing, i.e., the actual material tests were not conducted unless the AK dentists confirmed that all testing conditions had been met. Material testing consisted of an orally administered test sample, followed by an examination of whether changes in the tone of specific muscles had occurred.
Examination 1
In the first part of the test, the AK dentists decided, for each test person, whether there was evidence of non-tolerability toward one or both materials. The most important objective of this test series was to allow the tester to obtain a clinically relevant classification on whether individual tolerability (1) or non-tolerability (2) was present.
Test persons who had the same response to either test material, whether both responses were "tolerable" or "non-tolerable", were excluded from further testing, since they could not be included in a blinded second testing. Conversely, if the judgment was such that there was non-tolerability (2) for one material and tolerability (1) for the other material, the test persons were further examined in the blinded part of the study.
If a test person indicated non-tolerability toward a sample, she or he was asked to rinse her/his mouth with water for 10 sec before testing was continued. Additionally, the kinesiologic pre-test (examination of normal muscle tone, etc.) was repeated in these cases.
Examination 2
The blinded test for determining retest-reliability was done after completion of the open (first) test. With a sample size of 40 subjects, the achieved power was 91.2% in the case of a medium effect size (0.74 vs. 0.50), and 99.9% in the case of a large effect size (0.86 vs. 0.50), to yield a statistically significant result (Cohen, 1988; Altman et al., 2000).
During the blind test, the AK dentists tested one of the samples that had been identified as "tolerant" (1) or "intolerant" (2) during the open test phase. Since the test specimens were encoded, it was impossible for both tester and study participants to predict which material was used. Codification was accomplished by means of a random-number table (from 1 through 40). For each number, one specimen of material I or II was hidden in an envelope of chlorine-free recycled paper (Kuvert-Grün C6 Nr. 1674-0, Berberich, Heilbronn, Germany). Each envelope was marked with a code number from 1 through 40. The table with random numbers had been set up by the observer prior to testing and kept in a sealed envelope.
The test person arbitrarily chose an envelope with a code number, opened it, and put the specimen in his/her mouth in such a way that neither he/she nor the tester could see the sample. Immediately thereafter, testing was continued. After the tester had made his decision, the result was recorded. The individual specimen was either tolerable (1) or intolerable (2). There was only one result for each participant. At this point, testing on the subject was finished. To prevent any influence on testers or tested subjects during the investigation, the participants were not given any results before the entire study was finished. During the ensuing evaluation of the results, all that was relevant was whether the statements of the open and the blinded test phases coincided. All relevant data were recorded on a previously prepared protocol page (Table 1
) under the supervision of an observer who had been chosen by the AK dentists (G.S.). Randomization and test evaluation were carried out by a test monitor (T.P.) after all testing had been terminated. Other observers of the evaluation process were the principal investigator of the study (H.S.), a participant in the study (M.K.), both AK dentists (R.M., C.F.), and a supervisor appointed by the AK representatives (G.S.) (see ACKNOWLEDGMENTS).
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The retrieval rate on all test persons (remaining part of equally classified test persons with discordant findings) was then compared by means of a simple binomial test and rate probability (Trampisch and Windeler, 2000). The exact 95% confidence interval was calculated.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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), 31 (28%) were considered inappropriate for further testing after kinesiologic pre-testing, for the following reasons: the presence of scars (11 persons), so-called "switching" (neurologic disorganization) (10 participants), "general muscle hypertone" (six individuals), "missing normal tone" (three subjects), and piercing (one person). All further testing was conducted on the remaining 81 study participants.
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The remaining 40 test persons were divided into two categories. The first category was tolerant to material I but intolerant to material II; for the second category, the opposite was true (n = 20, respectively).
During the open test phase (n = 81), both composites were classified by the AK dentists. Thirty-four test persons (42%) were classified as tolerant for both composites; 47 (7 + 40; 58%) were intolerant for at least one composite.
Examination 2
In the double-blinded test, a match with the results obtained in the first open test was found in 14 cases. In the remaining 26 cases, there was no agreement. The rate of correct judgments, therefore, was 14/40 = 0.35.
The performances of the two AK dentists differed: Dentist I (R.M.) examined 15 of the 40 cases in the blinded test, and achieved correspondence in four cases (27%). The assessment of dentist II (C.F.), who examined the remaining 25 cases, resulted in 10 matched cases (40%).
The 95% confidence interval of the retrieval rate was 35% (21%; 52%). Statistical evaluation with the binomial test yielded a p value of 0.9766. Hence, the working hypothesis was confirmed, i.e., accuracy of AK testing for the determination of the (in)tolerance of dental materials is not significantly higher than random probability.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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Our results showed that almost 30% of the initial pool of test persons had to be eliminated from further testing because of possible "negative influences" (such as scars, improper muscle tone, etc.). More than one-third of the initial pool of test persons (37%) showed equal reactions to both materials and had to be excluded for subsequent blinded reliability testing. Only 40 of the 112 initial individuals were available for this test. This means that, for future studies, it must be expected that three times as many test persons should recruited to provide an adequate pool for the final test evaluation.
During open testing, the composite probes were judged by 42% of all subjects as "tolerable" and by 58% of the individuals as "intolerable" for at least one material. Hence, the kinesiologically obtained rate of intolerability of dental materials (58%) is much higher than estimates reported in the dental literature, which considers adverse reactions as very rare events (McHugh, 1992; Stanley, 1992; Lygre et al., 2003).
It must be emphasized that the present study did not test actual intolerance or tolerance of these materials. Therefore, our investigation did not directly evaluate the validity of Applied Kinesiology by using a gold standard. However, any method that fails to be reliable cannot be valid.
Even though both AK dentists were highly experienced and qualified, their accuracy rates differed significantly (27% vs. 40%). They were given the prerogative to refuse testing due to insufficient or biased conditions in each individual case. No adverse influences were brought to light during testing, with regard to either exterior conditions or participating test persons.
According to Cohen (1988), effect sizes should be graded as small in the case of 60%, medium in the case of 74%, and large in the case of 86% hits, compared with a statistical likelihood of 50%. The chosen sample size of 40 evaluable subjects resulted in a power of 91.2% in the case of a medium effect size, and a power exceeding 99.9% in the case of a large effect size, to yield a statistically significant result. The sample size, therefore, was certainly sufficient for the detection of a reliable diagnostic tool (Cohen, 1988; Altman et al., 2000). The lack of statistically significant results cannot be explained by statistical weaknesses.
Possible causes for the frequent discrepancies between the results found in the open and blind tests were discussed at length with the AK dentists after completion of the investigation. As potential sources of error, the procedures for sample production, sample storage, and exterior conditions during testing were mentioned. The AK dentists suggested that storage of the encoded materials in the paper envelopes might have had a negative impact on the results. They believed that it was possible that material from the envelopes had contaminated the samples in a hitherto unknown way. As a consequence, the AK dentists proposed that future studies should also test the influence of the material samples’ storage conditions on the results of AK. Therefore, the results of the present study did not cause the two AK practitioners to cast any doubt on the validity of AK as being a suitable method for dental materials testing. Nonetheless, as far as testing of the tolerance of dental composites is concerned, AK does not appear to be a suitable diagnostic method.
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ACKNOWLEDGMENTS |
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Received October 20, 2004; Last revision July 15, 2005; Accepted August 3, 2005
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS & METHODSRESULTSDISCUSSIONREFERENCES |
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Cohen J (1988). Statistical power analysis for the behavioral sciences. 2nd ed. Hillsdale, NJ: Lawrence Erlbau Associates, pp. 147–150.
Eisenberg DM, Kessler RC, Foster C, Norlock FE, Calkins DR, Delbanco TL (1993). Unconventional medicine in the United States—prevalence, costs, and patterns of use. N Engl J Med 328:246–252.
Eisenberg DM, Davis RB, Ettner SL, Appel S, Wilkey S, Van Rompay M, et al. (1998). Trends in alternative medicine use in the United States, 1990–1997: results of a follow-up national survey. J Am Med Assoc 280:1569–1575.
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Kessler RC, Davis RB, Foster DF, Van Rompay MI, Walters EE, Wilkey SA, et al. (2001). Long-term trends in the use of complementary and alternative medical therapies in the United States. Ann Intern Med 135:262–268.
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Lygre GB, Gjerdet NR, Gronningsaeter AG, Björkman L (2003). Reporting on adverse reactions to dental materials—intraoral observations at a clinical follow-up. Community Dent Oral Epidemiol 31:200–206.[ISI][Medline]
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Trampisch HJ, Windeler J (2000). Medizinische statistik. Heidelberg: Springer, pp. 266–268.
Walther DC (1988). Applied kinesiology synopsis. Pueblo, CO: Systems, pp. 1–28.
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