LETTERS TO THE EDITOR More on fixed magnetic appliances To the Editor:
The response to our recent article about a fixed magnetic appliance (AM J ORTHODDENTOFACORTHOP 1989;95:467-78) questions: (1) the magnitude of vertical dental and skeletal changes and (2) the magnitude of growth changes. A detailed reading of the results shows that, in the control group, Pg moved horizontally and vertically in small amounts (H, 0.5 mm; V, 0.5 mm). In the treatment group, Pg moved a large amount (H, 2.9 mm; V, 1.9 mm), and the horizontal displacement was significantly greater than the vertical. It is inescapable that, generally, when mandibular growth occurs, there will be an increase in vertical height (the mandible does not normally displace parallel to the Frankfort horizontal plane). In skeletal Class II patients, enhanced horizontal mandibular growth is desirable, but an increase in vertical growth often is unavoidable. A major point to be noticed is that in this study, vertical displacement was less than would be expected with the precocious growth. As stated in the article, the gum tissue prevented occlusal contact of teeth at the time of appliance removal. If the gum tissue had not prevented further autorotation of the mandible, there would actually have been a decrease in hard-tissue facial height in these patients. The 3.8 mm reduction in overbite noticed on removal of appliances is no more than the sum of the incisor intrusion and an increase in vertical dimension. Again, if autorotation of the mandible had not been hindered by the gum tissue, the mandible could have closed further, in which case a reduction of overbite would not have been noticed. It was pointed out that the open bites that occurred were temporary in nature since the teeth reerupted into the interocclusal space.
Although the authors anticipated some growth alteration in the mandible, we too were surprised at the magnitude of mandible growth within 4 months of treatment. Since we have been historically skeptical of some claims in the literature regarding major treatment effects on mandibular growth, we looked for other explanations such as systemic errors in location of landmarks or sampling errors. No such errors were obvious. The fact that the increase in mandibular length is so large in comparison to the control group during treatment and growth reverts back to normal growth rate during the follow-up period further implies that the changes are real. Dr. Behrents has annualized the increase of mandibular growth in our study to 1 cm/year. However, this calculation is invalid and meaningless. Our results are for 4 months; longer-term effects are not known and the effects may be self-limiting. Wieslander' found a 3.4 mm increase in mandibular length in 5 months using a combination headgear-Herbst appliance. Similarly, Pancherz ~ showed an increase of 3.2 mm using the Herbst appliance for 6 months. It should be reemphasized that the publication describes a control study in human subjects investigating the effects of a fixed magnetic appliance. In the article we point out serious problems regarding the use of this appliance, including crossbites and soft-tissue pad contact. We do not yet know the optimal magnitude of force to use. From a clinical point of view, the appliance is a first attempt and is undergoing further development. Varun Kalra, BDS, MDS, MS Charles J. Burstone, DDS, MS Ravbzdra Nanda, BDS, AIDS, PhD Departnlent of Orthodontics School of Dental Medicine The University of Connecticut Health Center Farmhlgton, Conn.
Fig. 1. 27A
28A
Am. J. Orthod. Dentofac. Orthop. Januao' 1990
Letters to the editor
Fig. 2.
REFERENCES I. WieslanderL Intensive treatmentofsevcreClass II malocclusions with a headgear-Herbst appliance in the early mixed dentition. AM J OR'ntOD 1984;86:1-13. 2. Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance: a cephalometric investigation. AM J OR'rtlot) 1979;76."423-41. EDITOR'SNOTE:I have had a chance to measure the original headplates used in this study, and my measurements corroborate the study 100%. The important point is that the study covered only 4 months, and one cannot annualize the increments of increase. Actually, in the 4 months after treatment, for the sample, there was little or no mandibular growth. One other point has not been answered--that is, the possible role of the electrical field effect. Intensive research now being done in Sweden, Norway, and Germany shows that cellular enhancement under magnetic force is quite possible, just as it has been demonstrated in orthopedics, with the use of electromagnetic pulses to overcome the problem of nonunion of long bones. The headplates shown in Figs. ! and 2 were taken at the beginning of appliance placement (left), 4 months later on removal (center), and 4 months after treatment (right). Note posttreatment closure of posterior open bite that was created by bonded occlusal magnets. Significant sagittal improvement has occurred.
--T. M. Graber
Debate on orthognathic surge j continues To the Editor: I would like to comment on the letter from Bruce L. Douglas (AM J ORTHOD DENTOFACORTHOP 1989;96:22A23A) concerning orthognathic surgery. It is absolutely incredible to me that Dr. Douglas admits to "not being sufficiently knowledgeable about the reasons for removal of seemingly good, asymptomatic teeth for orthodontic reasons" yet is willing to appear in court as an "expert witness." I would recommend that
Dr. Douglas spend about an hour in the office of a welltrained orthodontist to be educated on this matter before appearing in court again and contributing to the "embarrassing and humiliating" experience that the sued dentist must agonizingly endure. It is an insult to orthodontists when Dr. Douglas goes on to state that "orthodontists do not comprehend how serious, traumatic, and potentially dangerous" orthognathic surgery can be. Is it possible that he does not realize that we are, above all, dentists who happen to specialize in orthodontics? Before becoming orthodontists, many of us had spent many hours engaged in oral surgery procedures. I cannot understand how a surgical procedure could be performed without the complete cooperation or "close harmony" of the orthodontist and surgeon. No matter how positive the orthodontist is that surgery is indicated, no surgery is possible without the complete approval of the surgeon. It would be appalling to discover that there are surgeons who would proceed with surgery with which they strongly disagree simply because it is being recommended by the orthodontist. I agree wholeheartedly with Dr. Douglas in his appropriate description of the facial muscle "memories" and his caveat that evidence is still lacking as to the stability and efficacy of many of the surgical procedures being recommended today. The bones are not inanimate blocks of wood that can be sectioned and placed where the doctors believe they should be. Bone can resorb and readapt and reposition itself, powered by the musculature and other soft tissues. There is no doubt that complications can occur, and I agree with Dr. Douglas that honest, informed consent is of great importance. An understanding of our willingness to chance the complications that can occur is also important to an individual who is willing to serve as an expert witness in "dozens of cases." The need for these surgical procedures arose out of the inability of orthodontic appliances alone to solve the disfiguring real-
The response to our recent article about a fixed magnetic appliance (AM J ORTHODDENTOFACORTHOP 1989;95:467-78) questions: (1) the magnitude of vertical dental and skeletal changes and (2) the magnitude of growth changes. A detailed reading of the results shows that, in the control group, Pg moved horizontally and vertically in small amounts (H, 0.5 mm; V, 0.5 mm). In the treatment group, Pg moved a large amount (H, 2.9 mm; V, 1.9 mm), and the horizontal displacement was significantly greater than the vertical. It is inescapable that, generally, when mandibular growth occurs, there will be an increase in vertical height (the mandible does not normally displace parallel to the Frankfort horizontal plane). In skeletal Class II patients, enhanced horizontal mandibular growth is desirable, but an increase in vertical growth often is unavoidable. A major point to be noticed is that in this study, vertical displacement was less than would be expected with the precocious growth. As stated in the article, the gum tissue prevented occlusal contact of teeth at the time of appliance removal. If the gum tissue had not prevented further autorotation of the mandible, there would actually have been a decrease in hard-tissue facial height in these patients. The 3.8 mm reduction in overbite noticed on removal of appliances is no more than the sum of the incisor intrusion and an increase in vertical dimension. Again, if autorotation of the mandible had not been hindered by the gum tissue, the mandible could have closed further, in which case a reduction of overbite would not have been noticed. It was pointed out that the open bites that occurred were temporary in nature since the teeth reerupted into the interocclusal space.
Although the authors anticipated some growth alteration in the mandible, we too were surprised at the magnitude of mandible growth within 4 months of treatment. Since we have been historically skeptical of some claims in the literature regarding major treatment effects on mandibular growth, we looked for other explanations such as systemic errors in location of landmarks or sampling errors. No such errors were obvious. The fact that the increase in mandibular length is so large in comparison to the control group during treatment and growth reverts back to normal growth rate during the follow-up period further implies that the changes are real. Dr. Behrents has annualized the increase of mandibular growth in our study to 1 cm/year. However, this calculation is invalid and meaningless. Our results are for 4 months; longer-term effects are not known and the effects may be self-limiting. Wieslander' found a 3.4 mm increase in mandibular length in 5 months using a combination headgear-Herbst appliance. Similarly, Pancherz ~ showed an increase of 3.2 mm using the Herbst appliance for 6 months. It should be reemphasized that the publication describes a control study in human subjects investigating the effects of a fixed magnetic appliance. In the article we point out serious problems regarding the use of this appliance, including crossbites and soft-tissue pad contact. We do not yet know the optimal magnitude of force to use. From a clinical point of view, the appliance is a first attempt and is undergoing further development. Varun Kalra, BDS, MDS, MS Charles J. Burstone, DDS, MS Ravbzdra Nanda, BDS, AIDS, PhD Departnlent of Orthodontics School of Dental Medicine The University of Connecticut Health Center Farmhlgton, Conn.
Fig. 1. 27A
28A
Am. J. Orthod. Dentofac. Orthop. Januao' 1990
Letters to the editor
Fig. 2.
REFERENCES I. WieslanderL Intensive treatmentofsevcreClass II malocclusions with a headgear-Herbst appliance in the early mixed dentition. AM J OR'ntOD 1984;86:1-13. 2. Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance: a cephalometric investigation. AM J OR'rtlot) 1979;76."423-41. EDITOR'SNOTE:I have had a chance to measure the original headplates used in this study, and my measurements corroborate the study 100%. The important point is that the study covered only 4 months, and one cannot annualize the increments of increase. Actually, in the 4 months after treatment, for the sample, there was little or no mandibular growth. One other point has not been answered--that is, the possible role of the electrical field effect. Intensive research now being done in Sweden, Norway, and Germany shows that cellular enhancement under magnetic force is quite possible, just as it has been demonstrated in orthopedics, with the use of electromagnetic pulses to overcome the problem of nonunion of long bones. The headplates shown in Figs. ! and 2 were taken at the beginning of appliance placement (left), 4 months later on removal (center), and 4 months after treatment (right). Note posttreatment closure of posterior open bite that was created by bonded occlusal magnets. Significant sagittal improvement has occurred.
--T. M. Graber
Debate on orthognathic surge j continues To the Editor: I would like to comment on the letter from Bruce L. Douglas (AM J ORTHOD DENTOFACORTHOP 1989;96:22A23A) concerning orthognathic surgery. It is absolutely incredible to me that Dr. Douglas admits to "not being sufficiently knowledgeable about the reasons for removal of seemingly good, asymptomatic teeth for orthodontic reasons" yet is willing to appear in court as an "expert witness." I would recommend that
Dr. Douglas spend about an hour in the office of a welltrained orthodontist to be educated on this matter before appearing in court again and contributing to the "embarrassing and humiliating" experience that the sued dentist must agonizingly endure. It is an insult to orthodontists when Dr. Douglas goes on to state that "orthodontists do not comprehend how serious, traumatic, and potentially dangerous" orthognathic surgery can be. Is it possible that he does not realize that we are, above all, dentists who happen to specialize in orthodontics? Before becoming orthodontists, many of us had spent many hours engaged in oral surgery procedures. I cannot understand how a surgical procedure could be performed without the complete cooperation or "close harmony" of the orthodontist and surgeon. No matter how positive the orthodontist is that surgery is indicated, no surgery is possible without the complete approval of the surgeon. It would be appalling to discover that there are surgeons who would proceed with surgery with which they strongly disagree simply because it is being recommended by the orthodontist. I agree wholeheartedly with Dr. Douglas in his appropriate description of the facial muscle "memories" and his caveat that evidence is still lacking as to the stability and efficacy of many of the surgical procedures being recommended today. The bones are not inanimate blocks of wood that can be sectioned and placed where the doctors believe they should be. Bone can resorb and readapt and reposition itself, powered by the musculature and other soft tissues. There is no doubt that complications can occur, and I agree with Dr. Douglas that honest, informed consent is of great importance. An understanding of our willingness to chance the complications that can occur is also important to an individual who is willing to serve as an expert witness in "dozens of cases." The need for these surgical procedures arose out of the inability of orthodontic appliances alone to solve the disfiguring real-
