- Email: [email protected]
A reply to Dr. Fränkel
Letters to editor
Volume 85 Number 5
7. Friinkel R, Friinkel C: Funktionelle Aspekte des skelettalen offenen B&es. Forts&r Kieferorthop 43: 8-18, 1982. 8. Frankel R, Frankel C: A functional approach to treatment of skeletal open bite. AM J ORTHOD 84: 54-68, 1983. 9. Tomer B, Harvold EP: Primate experiments on mandibular growth direction. AM J ORTHOD 82: 114-l 19, 1982. 10. Frankel R: A functional approach to orofacial orthopedics. Br J Grthod 7: 41-51, 1980. 11. Falck F: Sagittale und vertikale Verlnderungen bei mandibularer Retrognathie. Stomatol DDR 33: 182-195, 1983. 12. Slagsvold 0: Activator development and philosophy. In Graber
445
TM, Neumann B: Removable orthodontic appliances, Philadelphia, 1977, W. B. Saunders Company, pp. 133-182. 13. Little RM, Wallen TR, Riedel RA: Stability and relapse of mandibular anterior alignment-first premolar extraction cases treated by traditional edgewise orthodontics. AM J ORTHOD 80: 349-365, 1981. 14. Guthoerl F: Nachuntersuchung zur Stabilimt von kieferorthopadischen Behandlungsergebnissen am Unterkiefer. Zahnarxtl Welt Reform 5: 15, 1983. 15. Graber TM: Orthodontics, principles and practice, Philadelphia, 1972, W. B. Saunders Company.
A reply to Dr. Frknkel To the Editor: The points made in Dr. Frankel’s letter seem to be three: (1) that the appliance is used as a training appliance to help improve poor postural behavior of the facial musculature; (2) that Dr. Frankel no longer uses his appliance as described in my article, and in particular, that he “notches” the deciduous teeth; and (3) that Dr. Frankel accepts the need for controlled trials and, indeed, cites a recent paper based on thirty-five treated cases. I will deal with his first two points together, since the thrust of his argument is that if the teeth were not notched the appliance would not function as a training device. I repeat that the appliance construction was as taught by Dr. Frankel at the time the patients were under treatment, and this included preparation of the plaster models as recommended (that is, the teeth on the models were ground but not the teeth in the mouth, since it was said that this was not obligatory). The simple fact is that Dr. Frankel, for his part, has changed several aspects of his appliance’s design, construction, and application with the passage of time and while I would accept that he might not now be advising the methods employed in the treatment of my sample, he formerly did so. It is my belief that the paper shows that the function regulator as previously taught by Dr. Frankel and others produced principally dentoalveolar change. I have reread his articles in the English language, and while they extend to approximately 160 pages, I did not find a single reference to “notching,” which is surely rather curious in the light of the emphasis which he now seeks to place on it. Whether the appliance system if employed as he now recommends will produce different results is, of course, an open question. I, for one, would like to ask why it is that after between 20 and 30 years of using his appliance, the study to which he refers has only thirtyfive Class II. Division 1 cases in it, since this suggests
that careful case selection is being employed and that only the most successful results are being compared with controls. I openly challenge Dr. Frankel to produce either the data from consecutive cases which he has treated or, better, the resulting data for patients treated by his appliance system according to the elegant experimental design of Harvold and Vargervik3 in which alternate cases are placed in a control or experimental category and then all cases compared. In the discipline of orthodontics all too many “studies” have used the sleight of hand in which controls are compared with only the most successful results and not with the complete range of consecutively treated cases. This, in turn, leads, whichever appliance system is involved (fixed or functional), to the spurious conclusion that a statistically significant difference in the forward growth of the mandible or a clinically significant change in the skeletal relationship is produced by the appliance. The difference, however, is entirely a product of the way in which the “study” is set up. I would like to quote from an editorial4 in the AMERICAN JOURNAL OF ORTHODONTICS: “The common claim that the appliance is not used or designed correctly is misleading, since those claiming superiority of fabrication seem to change the design daily and, as a result, never have long-term results to report. Their position is safe because evaluation is impossible if the design is always changing and the hypotheses never needs verification. Each stage of change needs documentation and evaluation to avoid repetition in other offices.” Later in the same editorial, we find: “It is not a crime to demonstrate that a functional appliance behaves in a way similar to some fixed appliances with small changes in several areas leading to an improved dentofacial relationship. It is misleading, however, to present a highly selected series of cases as being representative of that found on average in one’s practice. It is time for some
446
Letters to editor
answers. We must determine whether the individual is different or whether the appliance is in control of the variance.” R. P. Scholz says, in his lgtter in the August issue, that “Frankel’s own publications show excellent evidence that this appliance has considerable orthopedic capability.” I question this statement and would refer your readers to Frankel’s paper to be found in the Transactions of the European Orthodontic Society (1966), in particular to Fig. 11, its caption, and the textual comment on page 246. I would suggest that while the anterior open bite has improved, this is demonstrably not brought about by the claimed alteration in the maxillomandibular plane angle but by movement of the incisor teeth. Scholz comments further on the proclination of incisor teeth. Readers can turn to a second article by Dr. Frankel, “The Treatment of Class II, Division 1 Malocclusion with Functional Correctors” (AM. J. ORTHOD. 55: 265275, 1969) and examine Figs. 5 and 10, which confirm that Dr. Frankel regularly proclines lower anterior teeth.
Am. J. Orthod.
May 1984
In conclusion, may I say that in my article I reported as fairly as I was able on the results observed, and I look forward to being convinced by the reported results of consecutively treated Frankel cases and their controls, whether these come from Zwickau or elsewhere.
N. R. E. Robertson Department of Orthodontics Dental
School
Heath Park CardifS CF4 4XY, Wales
REFERENCES 1. Fdnkel functional 2. Friinkel functional 3. Harvold treatment. 4. Watson
R: Treatment of Class II, Division 1 malocclusion with correctors. AM J ORTHOD 55: 265-275, 1969. R: The theoretical concept underlying the treatment with correctors. Trans Eur Orthod Sot, pp. 233-254, 1966. EP, Vargervik K: Morphogenetic response to activator AM J ORTHOD 60: 478-490, 1971. WG: Editorial. AM J ORTHOD 82: 519-521, 1982.
Response to Dr. Frlinkel Re: Paragraph
2
The concept that poor structural behavior of the musculature plays an important causative role in skeletal and occlusal Class II relationships does not seem to be valid in most circumstances. If the concept were valid, one would expect to see, clinically, good skeletal balance at birth, the establishment of a good occlusion in the deciduous dentition, and then aprogressive deterioration into a Class II occlusion and skeletal framework until the muscular imbalance was corrected. The occlusion should correct itself with corrected muscle balance and then remain stable, while the growth of the jaws should change to a harmonious growth pattern throughout the remaining growth period. However, our studies on the growth and development of the dentition and face have not shown this sequence to occur and refute this ethereal functional concept. Class II skeletal imbalances are present at birth. Class II occlusal relationships appear at the time the deciduous teeth erupt and remain relatively stable until the permanent incisors and first molars erupt. The labial eruption of these much larger permanent incisors makes the overjet much more noticeable, even. though the occlusion of the posterior deciduous teeth has remained the same. After the permanent incisors erupt, the Class II occlusal relationship remains relatively stable throughout the remaining growth period except for minor changes that occur during the transition from the mixed dentition to the permanent dentition or until some type of Class II corrective therapy is initiated. Although the anteroposterior occlusion of the teeth
remains relatively stable during growth, the jaws appear to grow independently of each other and can result in changing jaw relationships, the mandible usually moving forward more than the maxilla. It has not been shown that the jaw relationships of Class II malocclusions usually become worse with growth. These changing jaw relationships (unless excessive) are practically impossible to detect clinically because they are masked by the migration of the teeth within their jaws, which maintains a constant occlusion. This same phenomenon (constant occlusion with changing jaw relationships) is observed in Class I, Class II, and Class Ill occlusions and, therefore, implies that the occlusion of the teeth with their related muscle function does not influence the growth of the jaws! The infant human head is predominantly cranium with a very small lower face. In the transition to the adult human head, the lower face grows downward and forward much more than the cranium, producing the balance between the cranium and face. This means that the mandible grows forward more than the maxilla and the cranium. Translated to cephalometric measurements, pogonion comes forward more than A point and nasion; i.e., AN6 and convexity decrease. We find that maxillary and mandibular teeth migrate in the maxilla and mandible to compensate for the differential in jaw growth. In the vertical plane, posterior facial height usually increases more than anterior facial height. Measurements of the occlusal plane and mandibular plane decrease relative to the cranial base, not because the anterior
Volume 85 Number 5
7. Friinkel R, Friinkel C: Funktionelle Aspekte des skelettalen offenen B&es. Forts&r Kieferorthop 43: 8-18, 1982. 8. Frankel R, Frankel C: A functional approach to treatment of skeletal open bite. AM J ORTHOD 84: 54-68, 1983. 9. Tomer B, Harvold EP: Primate experiments on mandibular growth direction. AM J ORTHOD 82: 114-l 19, 1982. 10. Frankel R: A functional approach to orofacial orthopedics. Br J Grthod 7: 41-51, 1980. 11. Falck F: Sagittale und vertikale Verlnderungen bei mandibularer Retrognathie. Stomatol DDR 33: 182-195, 1983. 12. Slagsvold 0: Activator development and philosophy. In Graber
445
TM, Neumann B: Removable orthodontic appliances, Philadelphia, 1977, W. B. Saunders Company, pp. 133-182. 13. Little RM, Wallen TR, Riedel RA: Stability and relapse of mandibular anterior alignment-first premolar extraction cases treated by traditional edgewise orthodontics. AM J ORTHOD 80: 349-365, 1981. 14. Guthoerl F: Nachuntersuchung zur Stabilimt von kieferorthopadischen Behandlungsergebnissen am Unterkiefer. Zahnarxtl Welt Reform 5: 15, 1983. 15. Graber TM: Orthodontics, principles and practice, Philadelphia, 1972, W. B. Saunders Company.
A reply to Dr. Frknkel To the Editor: The points made in Dr. Frankel’s letter seem to be three: (1) that the appliance is used as a training appliance to help improve poor postural behavior of the facial musculature; (2) that Dr. Frankel no longer uses his appliance as described in my article, and in particular, that he “notches” the deciduous teeth; and (3) that Dr. Frankel accepts the need for controlled trials and, indeed, cites a recent paper based on thirty-five treated cases. I will deal with his first two points together, since the thrust of his argument is that if the teeth were not notched the appliance would not function as a training device. I repeat that the appliance construction was as taught by Dr. Frankel at the time the patients were under treatment, and this included preparation of the plaster models as recommended (that is, the teeth on the models were ground but not the teeth in the mouth, since it was said that this was not obligatory). The simple fact is that Dr. Frankel, for his part, has changed several aspects of his appliance’s design, construction, and application with the passage of time and while I would accept that he might not now be advising the methods employed in the treatment of my sample, he formerly did so. It is my belief that the paper shows that the function regulator as previously taught by Dr. Frankel and others produced principally dentoalveolar change. I have reread his articles in the English language, and while they extend to approximately 160 pages, I did not find a single reference to “notching,” which is surely rather curious in the light of the emphasis which he now seeks to place on it. Whether the appliance system if employed as he now recommends will produce different results is, of course, an open question. I, for one, would like to ask why it is that after between 20 and 30 years of using his appliance, the study to which he refers has only thirtyfive Class II. Division 1 cases in it, since this suggests
that careful case selection is being employed and that only the most successful results are being compared with controls. I openly challenge Dr. Frankel to produce either the data from consecutive cases which he has treated or, better, the resulting data for patients treated by his appliance system according to the elegant experimental design of Harvold and Vargervik3 in which alternate cases are placed in a control or experimental category and then all cases compared. In the discipline of orthodontics all too many “studies” have used the sleight of hand in which controls are compared with only the most successful results and not with the complete range of consecutively treated cases. This, in turn, leads, whichever appliance system is involved (fixed or functional), to the spurious conclusion that a statistically significant difference in the forward growth of the mandible or a clinically significant change in the skeletal relationship is produced by the appliance. The difference, however, is entirely a product of the way in which the “study” is set up. I would like to quote from an editorial4 in the AMERICAN JOURNAL OF ORTHODONTICS: “The common claim that the appliance is not used or designed correctly is misleading, since those claiming superiority of fabrication seem to change the design daily and, as a result, never have long-term results to report. Their position is safe because evaluation is impossible if the design is always changing and the hypotheses never needs verification. Each stage of change needs documentation and evaluation to avoid repetition in other offices.” Later in the same editorial, we find: “It is not a crime to demonstrate that a functional appliance behaves in a way similar to some fixed appliances with small changes in several areas leading to an improved dentofacial relationship. It is misleading, however, to present a highly selected series of cases as being representative of that found on average in one’s practice. It is time for some
446
Letters to editor
answers. We must determine whether the individual is different or whether the appliance is in control of the variance.” R. P. Scholz says, in his lgtter in the August issue, that “Frankel’s own publications show excellent evidence that this appliance has considerable orthopedic capability.” I question this statement and would refer your readers to Frankel’s paper to be found in the Transactions of the European Orthodontic Society (1966), in particular to Fig. 11, its caption, and the textual comment on page 246. I would suggest that while the anterior open bite has improved, this is demonstrably not brought about by the claimed alteration in the maxillomandibular plane angle but by movement of the incisor teeth. Scholz comments further on the proclination of incisor teeth. Readers can turn to a second article by Dr. Frankel, “The Treatment of Class II, Division 1 Malocclusion with Functional Correctors” (AM. J. ORTHOD. 55: 265275, 1969) and examine Figs. 5 and 10, which confirm that Dr. Frankel regularly proclines lower anterior teeth.
Am. J. Orthod.
May 1984
In conclusion, may I say that in my article I reported as fairly as I was able on the results observed, and I look forward to being convinced by the reported results of consecutively treated Frankel cases and their controls, whether these come from Zwickau or elsewhere.
N. R. E. Robertson Department of Orthodontics Dental
School
Heath Park CardifS CF4 4XY, Wales
REFERENCES 1. Fdnkel functional 2. Friinkel functional 3. Harvold treatment. 4. Watson
R: Treatment of Class II, Division 1 malocclusion with correctors. AM J ORTHOD 55: 265-275, 1969. R: The theoretical concept underlying the treatment with correctors. Trans Eur Orthod Sot, pp. 233-254, 1966. EP, Vargervik K: Morphogenetic response to activator AM J ORTHOD 60: 478-490, 1971. WG: Editorial. AM J ORTHOD 82: 519-521, 1982.
Response to Dr. Frlinkel Re: Paragraph
2
The concept that poor structural behavior of the musculature plays an important causative role in skeletal and occlusal Class II relationships does not seem to be valid in most circumstances. If the concept were valid, one would expect to see, clinically, good skeletal balance at birth, the establishment of a good occlusion in the deciduous dentition, and then aprogressive deterioration into a Class II occlusion and skeletal framework until the muscular imbalance was corrected. The occlusion should correct itself with corrected muscle balance and then remain stable, while the growth of the jaws should change to a harmonious growth pattern throughout the remaining growth period. However, our studies on the growth and development of the dentition and face have not shown this sequence to occur and refute this ethereal functional concept. Class II skeletal imbalances are present at birth. Class II occlusal relationships appear at the time the deciduous teeth erupt and remain relatively stable until the permanent incisors and first molars erupt. The labial eruption of these much larger permanent incisors makes the overjet much more noticeable, even. though the occlusion of the posterior deciduous teeth has remained the same. After the permanent incisors erupt, the Class II occlusal relationship remains relatively stable throughout the remaining growth period except for minor changes that occur during the transition from the mixed dentition to the permanent dentition or until some type of Class II corrective therapy is initiated. Although the anteroposterior occlusion of the teeth
remains relatively stable during growth, the jaws appear to grow independently of each other and can result in changing jaw relationships, the mandible usually moving forward more than the maxilla. It has not been shown that the jaw relationships of Class II malocclusions usually become worse with growth. These changing jaw relationships (unless excessive) are practically impossible to detect clinically because they are masked by the migration of the teeth within their jaws, which maintains a constant occlusion. This same phenomenon (constant occlusion with changing jaw relationships) is observed in Class I, Class II, and Class Ill occlusions and, therefore, implies that the occlusion of the teeth with their related muscle function does not influence the growth of the jaws! The infant human head is predominantly cranium with a very small lower face. In the transition to the adult human head, the lower face grows downward and forward much more than the cranium, producing the balance between the cranium and face. This means that the mandible grows forward more than the maxilla and the cranium. Translated to cephalometric measurements, pogonion comes forward more than A point and nasion; i.e., AN6 and convexity decrease. We find that maxillary and mandibular teeth migrate in the maxilla and mandible to compensate for the differential in jaw growth. In the vertical plane, posterior facial height usually increases more than anterior facial height. Measurements of the occlusal plane and mandibular plane decrease relative to the cranial base, not because the anterior