Functional orthopedics and activator treatment

Dr Wilson also questions whether the appliances used in the Otago studies were made by competent technicians, and whether the clinicians concerned were experienced in the use of these appliances. A rereading of “Materials and Methods” in the initial Otago study1 (which Dr Wilson quotes) would clearly satisfy his doubts. Dr Wilson’s comment that it is irrelevant to study “outdated” appliances such as the Harvold and Fränkel ignores the fact that osteoblasts and osteoclasts cannot differentiate between “outdated” and “currently fashionable” appliances. The different effects of a Harvold compared with a Fränkel warrant investigation because 1 appliance is tooth borne and the other is tissue borne, and both had been supposed to work by different mechanisms.1-4 Dr Wilson also states that wearing the Twin-block appliance for a full 24 hours a day makes the correction of Class II dental base relationships considerably more effective and quotes a study by Trenouth8 to support this statement. This conclusion cannot be substantiated from the Trenouth study, however, and there is no guarantee that any removable appliance will be worn for 24 hours a day anyway. (It is worth noting here that Tulloch et al,9 in a large, randomized control trial investigating the treatment effects of functional appliances, concluded that there was no linear relationship between the magnitude of treatment response and general compliance, and that cooperation, although important, is unlikely to be a factor in determining treatment response.) The purpose of well-matched controls in clinical trials is to separate the effect of normal growth from treatment effects, and in the Trenouth study8 a selected sample of Class II Division 1 cases successfully treated with the twin block appliance were compared with a control group formed from normative data. This is like comparing apples and oranges, and biased sample selection such as this can suggest orthopedic changes, when in fact the changes may indicate nothing more than favorable growth.10-12 Dr Wilson also notes that the O’Neill et al study4 is intentionally misleading when it concludes “that treatment with functional appliances does not lead to more attractive profiles than nontreatment.” Yet this conclusion agrees with that of Livieratos and Johnston 13 that the facial and skeletal changes produced by 2 different types of treatments (1-stage fixed and 2-stage functional-fixed) left patients indistinguishable from each other, and that an early phase of functional appliance treatment appeared to provide no unique benefits, contrary to the beliefs of the functional orthodontists. It is therefore perfectly reasonable, as Dr Turpin14 suggests, that the results of the O’Neill et al study4 make it unwise for a clinician to promise that functional appliance treatment will improve the attractiveness of a growing patient’s profile. If Dr Wilson’s conclusions form the basis of his functional orthodontics practicing philosophy, then perhaps a course in elementary clinical epidemiology and scientific literature evaluation would be in order. Vig15 summed up the situation quite clearly when he wrote, “training programs which produce clinicians unable to assess evidence according to current scientific standards perpetuate the problems by validating yesterday’s superstitions and today’s follies as the ‘art’ of practice; paving the way for tomorrow’s fads; and creating a generation of trained ‘believ-

ers,’ instead of competent critics immune to the claims of pseudo-progress.” Michael D. Courtney, BDS, MDS, and Trevor J. Leigh, BDS, MDS Palmerston North, New Zealand REFERENCES 1. Nelson C, Harkness M, Herbison P. Mandibular changes during functional appliance treatment. Am J Orthod Dentofacial Orthop 1993;104:153-61. 2. Courtney M, Harkness M, Herbison P. Maxillary and cranial base changes during treatment with functional appliances. Am J Orthod Dentofacial Orthop 1996;109:616-24. 3. Webster T, Harkness M, Herbison P. Associations between changes in selected facial dimensions and the outcome of orthodontic treatment. Am J Orthod Dentofacial Orthop 1996:110:46-53. 4. O’Neill K, Harkness M, Knight R. Ratings of profile attractiveness after functional appliance treatment. Am J Orthod Dentofacial Orthop 2000;118:371-6. 5. Sackett DL, Hayes RB, Tugwell P. Clinical epidemiology: a basic science for clinical medicine. 2nd ed. New York: Little, Brown and Co; 1991. 6. Tulloch JFC, Medland W, Tuncay OC. Methods used to evaluate growth modification in Class II malocclusion. Am J Orthod Dentofacial Orthop 1990;98:340-7. 7. Turpin DL. Evidence-based orthodontics. Am J Orthod Dentofacial Orthop 2000;118:591. 8. Trenouth MJ. Cephalometic evaluation of the Twin-block appliance in the treatment of Class II Division 1 malocclusion with matched normative growth data. Am J Ortho Dentofacial Orthop 2000;117:54-9. 9. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome of early treatment for Class II malocclusion. Am J Orthod Dentofacial Orthop 1997;111:533-42. 10. Johnston LE. A comparative analysis of Class II treatments. In: Vig PS, Ribbens KA, editors. Science and clinical judgement in orthodontics. Monograph 19, Craniofacial growth series. Ann Arbor: Center for Human Growth and Development, University of Michigan; 1986. p. 103-48. 11. Cohen AM. The study of Class II division 1 malocclusions treated by the Andresen appliance. Br J Orthod 1981;8:159-63. 12. Mills JRE. Clinical control of craniofacial growth: a skeptic’s view point. In: McNamara JA, Ribbens KA, Howe RP editors. Clinical alteration of the growing face. Monograph 14, Craniofacial growth series. Ann Arbor: Center for Human Growth and Development, University of Michigan; 1983. p. 17-39. 13. Livieratos FA, Johnston LE. A comparison of one-stage and twostage non-extraction alternatives in matched Class II samples. Am J Orthod Dentofacial Orthop 1995;108:118-31. 14. Turpin DL. What patients want, and what they need. Am J Orthod Dentofacial Orthop 2000;118:365. 15. Vig PS. Clinical evidence in orthodontics: New clothes for the emperor. In: Vig KD and Vig PS, eds. Clinical research as the basis of clinical practice. Monograph 25, Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development, University of Michigan; 1991. p. 203-22. 0889-5406/2001/$35.00 + 0 8/8/118624 doi:10.1067/mod.2001.118624

Functional orthopedics and activator treatment I have some comments on the article “Rating of profile attractiveness after functional appliance treatment” (O’Neill K, Harkness M, Knight R. Am J Orthod Dentofacial Orthop 2000;118:371-6) and to the letter of Rolf Fränkel (Am J Orthod Dentofacial Orthop 2001;119(5):11A).

American Journal of Orthodontics and Dentofacial Orthopedics/September 2001

19A

Dr Fränkel, whose work I very much appreciate, claims that after activator treatment proclination of the lower incisors can always be observed. This means that, instead of an orthopedic effect, a dentoalveolar compensation is achieved. That must not be; it is not the rule. Depending on the growth pattern, the pecularities of the malocclusion, and the design of the appliance, it is possible to simultaneously upright the lower incisors and position the mandible anteriorly. How to do it? According to Dr Fränkel, it can done by using the principle of an anterior orientation of the mandible without touching the lower incisors, modified for the activator. The lingual surface of the lower incisors is not in contact with the acrylic; in this region, the acrylic is trimmed free. The advantage of the activator is that the incisors can be held by capping or

20A

even uprighted with an activated lower labial bow. The design for the lower incisor area is described in Dentofacial Orthopedics with Functional Appliances (Graber TM, Rakosi T, Petrovic AG. St. Louis: Mosby; 1997) on pages 201-7. In the same book, some Class II cases are presented where the originally proclined lower incisors were uprighted during activator treatment from 97˚ to 92.5˚ (p. 177-8) or from 103˚ to 91˚ (p. 427-8). Thomas Rakosi, Professor and head emeritus, Orthodontic Department, University of Freiburg, Germany 0889-5406/2001/$35.00 + 0 8/8/118928 doi:10.1067/mod.2001.118928 Am J Orthod Dentofacial Orthop 2001;120:18A-20A Copyright © 2001 by the American Association of Orthodontists.

American Journal of Orthodontics and Dentofacial Orthopedics/September 2001