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One-phase versus two-phase treatment
One-phase versus two-phase treatment Anthony A. Gianelly, DMD, PhD, MD" Boston, Mass.
T h e r e are few more compelling and controversial issues in orthodontics than the "timing" of treatment of the various problems encountered in growing patients. Most often, the principal concern is the benefit of treatment in the deciduous early mixed dentition stage of development when compared with treatment started in the late mixed dentition stage of development or in the permanent dentition. One reason for the controversy is that the accepted "cost" of an early treatment time is a two-phase protocol. Phase 1 generally involves 6 to 12 months of active treatment with the intent to change skeletodental relationships. Phase 2 is the "finishing" process after the eruption of appropriate permanent teeth. Thus, risk/reward analysis becomes inevitable. Do the benefits of early intervention justify the cost of two-phase treatment? Two recent reports are of interest to define the scope of the problem. The Journal of Clinical Orthodontics survey of diagnosis and therapeutics noted that approximately 25% of all patients are treated in a two-phase manner.' The AAO May Bulletin indicated that approximately 1.3 million persons in 1992 elected orthodontic treatment. At 25% penetration, at least 300,000+ patients are in a twophase treatment program. There are only 900,000+ growing patients since adults comprise 20% to 25% of the patient population.' Essentially, a third of all children are treated in two phases. The premise of this article is that at least 90% of all growing patients can be treated successfully in only one phase by starting treatment in the late mixed dentition stage of development-identified by the exfoliation of all deciduous teeth except the deciduous second molars or the "E"s. Implicit in this view is that there are few, if any, benefits that are unique to and dependent on earlier treatment. Also implicit is that habit control, the use of passive appliances such as space maintainers and minor alignment of incisors for esthetic or trauma reasons, is not considered part of conventional twophase treatment. ~Professor and Chairman, Department of Orthodontics, Boston University School of Graduate Dentistry. AM J ORTHOD DENTOFAC ORTHOP 1995;1118:556~9. Copyright © 1995 by the American Association of Orthodontists. 0889-5406/95/$5.00 + 0 8/1/60751
556
The other 5% to 10% of patients includes those with crossbites complicated by a mandibular shift and certain patients with Class III malocclusions who could benefit from immediate resolution of the problem. Consider the correction of the two most common orthodontic problems: crowding in either Class I or Class II malocclusions and the correction of Class II malocclusions. Crowding." Since lower arch conditions generally determine the course of treatment, only the changes in the lower arch will be discussed. The leeway space can provide adequate space to accommodate an aligned dentition in the vast majority of patients. 2 For example, an evaluation of the mandibular models of 100 patients in the mixed dentition stage of development revealed that 85 of the 100 subjects demonstrated crowding, which averaged between 4 to 5 ram. However, 62 (73%) of these 85 patients with crowding had sufficient space to align the teeth when the leeway space gain was included in the analysis. Thus, crowding can be resolved in 73% of patients with crowding in the mixed dentition stage of development simply by preserving and using the leeway space. (Since the combined mesiodistal diameters of the deciduous canine and first molar are essentially the same as the mesiodistal diameters of the permanent canine and first premolar, ~ the space gain, in actuality, represents the "E" space.) Maintaining the "E" space can readily be accomplished by starting treatment in the late mixed dentition stage. One exception might be the placement of a passive lingual arch to preserve arch length when a deciduous canine is lost prematurely. In the 100 patients evaluated, the nonextraction rate for alignment purposes would be 77% when the 15 patients who have no crowding in the mixed dentition stage are included. In 7 of the remaining 23 patients, the crowding did not exceed 2 mm; whereas in 16 patients, the crowding, even after "E" space preservation, exceeded 2 ram. A more aggressive nonextraction approach, which has been recommended, is to start treatment at an earlier age to "develop" the lower arch by using force systems that will lead to active and/or passive expansion of the arch. 4 Two common sys-
American Journal of 01~hodontics and Dento)acial Orthopedics Volume 108, No. 5
tems for this purpose are the use of a lip bumper and rapid palatal expansion (RPE) treatment to induce spontaneous expansion of the lower arch as the maxillary arch widens, The lip bumper can gain space since both arch length and width generally increase after lip bumper placement. 57 However, in view of the report by Little et al. s that the largest amount of postretention irregularity of any group studied was noted in a group of mixed dentition patients whose treatment involved more than 1 mm of arch length expansion, it seems prudent to limit the lip bumper to a 1 mm increase in arch length. This can generally be accomplished if lip bumper treatment begins after the eruption of the first premolar. Specifically, Bergersen indicated that a 1 mm gain in arch length is fairly common after 3 to 6 months of lip bumper therapy. 7 Since a 1 mm gain of arch length would reduce 2 mm of crowding, this late mixed dentition treatment would resolve the crowding in the seven patients with 2 mm or less of crowding. Therefore, with treatment that could be started in the late mixed dentition stage of development, the teeth can be aligned in 84% of the patients in this sample by nonextraction procedures. Would earlier intervention with R P E "develop" the lower arch sufficiently to avoid extractions? 9 In the transverse dimension, a focal point is the expansion of the intercanine width because this increase provides more space for alignment than any other transverse change. Germane et al. '° determined that 1 mm of intercanine expansion produces a 0.73 mm increase in arch perimeter, whereas a l mm expansion of the molars produces only a 0.27 mm increase. There are two studies that are relevant. Sandstrom et al. '~ noted only a 1.1 mm postretention increase in mandibular intercanine dimension in 28 patients whose maxillae were expanded orthopedically. Adkins et al. '2 found, at most, only 0.8 mm lower arch expansion incident to RPE. Thus neither investigation provides optimistic evidence that the lower intercanine dimension will expand more than 1 mm when the maxilla is orthopedically expanded. The transverse dimension of the arch can also be expanded actively. On presumption is that expansion performed at an earlier age might be stable. Since there is no suture, '3 any expansion is dental in nature. Again there are two studies to consider. Lutz and Poulton '4 evaluated the transverse changes that occurred in 13 patients whose lower arch was
Gianelly
557
expanded in the deciduous dentition stage of development and compared these changes to those observed in 12 control subjects. Expansion was accomplished with removable appliances in 11 patients and with fixed appliances in the remaining 2 patients. After a 3-year retention period, the patients were followed for another 3 years. At this time, there was no difference in intercanine dimension between the groups, indicating total relapse of the treatment gain. The relapse of intercanine expansion noted in this study reinforces the findings in the vast majority of investigations that have verified the instability of intercanine expansion in the mandibular arch. ~-~-23 In contrast, Crozat appliances were used to expand the transverse dimension of the lower arch in 5- to 6-year-old patients and retained the changes until all the deciduous teeth exfoliated. 24 After retention was discontinued, the arches remained stable. In this study, there were no control subjects, and data from published sources were used to represent the controls. As such, the actual net expansion (treatment change-growth change) was not reported. At best, by extrapolation, it appeared to approximate 2 to 3 mm. In summary, crowding can be resolved readily in up to 84% of all patients with treatment that need be started no earlier that the late mixed dentition stage of development because the space necessary for alignment in most patients with crowding is gained principally by " E " space control. (To reiterate, the main exception is the placement of a lingual arch). Should the other 16% of the patients be treated earlier than the late mixed dentition stage of development to pursue a nonextraction approach more aggressively? Those who support this view imply that earlier treatment can produce unique results specific to early intervention and these changes can avoid extractions. However, the previously cited evidence indicates that there are no substantial unique benefits related to earlier intervention. In addition, the stability of procedures that are designed to avoid extraction by developing the arches has not been established. The only available study in which the stability of expansion procedures performed in the mixed dentition stage of development is not encouraging since, as mentioned previously, the investigators noted more posttreatment instability when compared with other groups they had examined, s This conclusion is supported by the findings of Glenn et al.: 23 Stability of nonextraction treatment was associated with lower arch dimen-
558
Gianelly
sions that were effectively not expanded during treatment. In their sample, intercanine dimension was 25.4 mm before treatment and 26.0 mm after treatment. Arch length initially was 60.0 ram, and after treatment, it was 60.2 ram. Also, arch development that involves transverse expansion of the intercanine dimension is contrary to the vast majority of available data that document the futility of intercanine expansion. ~5-23 Accordingly, the burden to verify the stability of lateral expansion when performed at an early age is placed on those who propose this strategy. If extraction treatment (which the author prefers) is selected for this group of patients, should they be treated according to a serial extraction protocol, and does this not constitute two-phase treatment? The serial extraction decision, which is complex, does not usually involve active treatment. The first phase, traditionally, is a diagnostic-observation phase with no appliance placement. As such, there is no "protracted treatment time" price to pay. Class H malocclusions: If treatment is started in the late mixed dentition stage of development, at least 90% of all children with Class II malocclusions with or without crowding can be treated successfully in one phase, which lasts between 2 and 3 years. There are a number of procedures used to correct these problems and all function well at this age. For example, one method of correction involves the distal movement of the maxillary molars to convert the Class II malocclusion to a Class I spacing problem. This movement is routinely successful at this age because molars can be moved distally 1 to 2 mm per month during this time period, -~5"26 and mandibular growth is apparently sufficient to aid in correcting the Class I! malocclusion. In addition, continuous acting force systems that are not cooperation dependent have been developed 27 to overcome the compliance problem of extraoral appliances. This means that Class II molar relationships can be converted to Class I in 4 to 6 months with little difficulty. Accordingly, earlier intervention is not necessary. As an example, after 3 to 4 months of treatment with continuous extraoral forces, Armstrong noted between 4 to 7 mm of distal movement of the molars in patients in the late mixed dentition stage of development. 25 He also observed an apparent age dependency related to distal molar movement and stated that the "clinical response in the early permanent dentition to continuous extraoral force has not proved rapid enough to justify full time wear of the appli-
American Journal of Orthodontics and DentoJhcial Orthopedics November 1995
ance." This observation reinforces the view that appropriate time to start treating patients with Class II malocclusions is the late mixed dentition stage of development. There is a concern that earlier intervention with extraoral appliances might obtain more of a maxillary orthopedic effect that would be important for patients with maxillary prognathism. Unfortunately, the information is inadequate to support a conclusion. In one study, Wieslander compared the results of extraoral appliance use in patients in the early and late mixed dentition and noted a 1 mm greater orthopedic effeCt in the younger group? 8 The "cost" of the 1 mm is two-phase treatment (which, to me, is not a useful cost/benefit ratio.) For patients with Class II malocclusions characterized by mandibular retrognathism, use of functional appliances, with the intent to stimulate mandibular growth, has been advocated. 4 The appropriate time for optimal use of these appliances is not clear. McNamara et al. 2~ demonstrated an age dependent mandibular growth response with the use of the functional regulator-2 appliance when they recorded more mandibular growth in patients who were older than 10.5 years in comparison with the mandibular growth noted in younger patients. In their study, they divided patients according to age into a younger group (less than 10.5 years) and an older group (greater than 10.5 years) and observed 3.2 mm/year mandibular growth in the younger group compared with 4.0 mm/year in the older patients. Thus the mandibular response favored later intervention. The mandibular growth response noted with the Herbst appliance does not appear to be age dependent. 3°'31 For instance, Wieslander treated a group of 8- to 9-year-old patients and recorded 3.4 mm of mandibular growth after 5 months of treatment with the Herbst appliance?" Pancherz, whose patients were 10 to 11 years old, also noted 3.2 mm of mandibular growth after 6 months of Herbst therapy? ~Again, the mandibular response does not justify early intervention. Wieslander also attempted to achieve the "best of both orthopedic worlds" by intensive phase 1 treatment of young patients with combined application of an extraoral and a Herbst appliance. The protrusions were reduced rapidly, and the profiles straightened in phase 1. However, the pause between phase 1 and phase 2 became a problem since overjet reappeared in a number of patients. This led to a prolonged retention phase that extended beyond 3 years in some instances? 2
American Journal oJ' Orthodontics and DentoJhcial Orthopedics Volume 108, No. 5
When these patients and a control group were evaluated 8 to 9 years later, there was no statistical difference in mandibular length and forward position of the mandible. 32 This experience brings the cost/benefit issue into sharp focus. Are children with common problems gaining adequate benefits to justify the time and expense incurred with two-phase treatment? The proposal supported in this treatise is that for more than 90% of the patients, essentially all treatment goals can be accomplished in one phase of treatment when treatment is started in the late mixed dentition stage of development. REFERENCES 1. Gottlieb EL, Neslon AH, Vogels IlI DS. 1990 study of orthodontic diagnosis and treatment procedures. Part 2. J Clin Orthod 1991;25:223-30. 2. Arnold S. Analysis of leeway space in the mixed dentition. [Thesis.] Boston: Boston University, 1991. 3. Moyers RE, van der Linden FPGM, Riolo ML, McNamara JA Jr. Standards of human occlusal development. Monograph 5. Craniofacial Growth Series. Ann Arbor: Center of Human Development, The University of Michigan, 1976. 4. McNamara JA Jr, Brudon WL. Orthodontic and orthopedic treatment in the mixed dentition. Ann Arbor: Needham Press, 1993. 5. Nevant CT, Buschang PH, Alexander RG, Steffan JM. Lip bumper therapy for gaining arch length. AM J ORTHOD DENTOFAC ORTHOP 1991;100:330-6. 6. Osborne WS, Nanda RS, Currier GF. Mandibular arch perimeter changes wit h lip bumper treatment. AM J ORTHOD DENTOFAC ORTHOP 1991;99:527-32. 7. Bergersen EO. A cephalometric study of the clinical use of the mandibular labial bumper. AM J ORTHOD 1972;61:578602. 8. Little RM, Reidel RA, Stein A. Mandibular arch length increase during the mixed dentition: postretention evaluation of stability and relapse. AM J ORTHOD DENTOFAC ORTHOP 1990;97:393-404. 9. Haas A. Long-term post-treatment evaluation of rapid palatal expansion. Angle Orthod 1980;50:189-217. 10. Germane N, Lindauer SJ, Rubenstein LK, Rever JH, Isaacson RJ. Increase in arch perimeter due to orthodontic expansion. AM J ORTHOD DENTOFAC ORTHOP 1991;100: 421-7. 11. Sandstrom RA, Klapper L, Papaconstantinou S. Expansion of the lower arch concurrent with rapid maxillary expansion. AM J ORTHOD DENTOFAC ORTHOP 1988;94:296-302. 12. Adkins MA, Nanda RS, Currier GF. Arch perimeter changes on rapid palatal expansion. AM J ORTHOD DENTOFAC ORTHOP 1990;97:194-9. 13. Burstone CJ. Perspective on orthodontic stability. In: Nanda R, Burstone CJ, eds. Retention and stability in orthodontics. Philadelphia: WB Saunders;1993:52. 14. Lutz HD, Poulton DR. Stability of dental arch expansion in the deciduous dentition. Angle Orthod 1985;55:299-315.
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15. Peak JD. Cuspid stability. AM J ORTHOD 1956;42:608-14. 16. Bishara SE, Chada JM, Potter RB. Stability of intercanine width, overbite, and overjet correction. AM J ORTHOD 1973;63:588-95. 17. Shapiro PA. Mandibular dental arch form and dimension. AM J ORTHOD 1974;66:58-70. 18. Kuftinec MM. Effect of edgewise treatment and retention of mandibular incisors. AM J ORTHOD 1975;68:316-22. 19. El-Mangoury NH. Orthodontic relapse in subjects with varying degrees of anteroposterior and vertical dysplasia. AM J ORTHOD 1979;75:548-61. 20. Sondhi A, Cleall JF, BeGole EA. Dimensional changes in the arches of orthodontically treated cases. AM J ORTHOD 1986;77:60-74. 21. Little RM, Wallen TR, Reidel RA. Stability and relapse of mandibular anterior alignment-first premolar extraction cases treated by conventional edgewise orthodontics. AM J ORTHOD 1981;80:349-65. 22. Uhde MD, Sadowsky (2, BeGole EA. Long-term stability of dental relationships after orthodontic treatment. Angle Orthod 1983;53:240-52. 23. Glenn G, Sinclair PM, Alexander RG. Nonextraction orthodontic therapy: posttreatment dental and skeletal stability. AM J ORTHOD DENTOFAC ORTHOP 1987;92:321-28. 24. Mclnaney JB, Adams RM, Freeman MM. A nonextraction approach to crowded dentitions in young children: early recognition and treatment. J Am Dent Assoc 1980;101: 251-7. 25. Armstrong MM. Controlling the magnitude duration and direction of extraoral force. AM J ORTHOD 1971;59:217-43. 26. Bernstein L, Ulbrich R, Gianelly AA. Orthopedics versus orthodontics in Class II treatment. AM J ORTHOD 1977;72: 549-59. 27. Gianelly AA, Bednar J, Dietz VS. Japanese NiTi coils used for molar distal movement. AM J ORTHOD DENTOFAC ORTHOP 1991;99:564-6. 28. Wieslander L. Early or late cervical traction therapy of Class II malocclusions in the mixed dentition. AM J ORTHOD 1975;67:432-9. 29. McNamara JA Jr, Bookstein FL, Shaughnessy TG. Skeletal and dental relationships following functional regulator therapy on Class II patients. AM J ORTHOD 1985;88:91-109. 30. Wieslander L. Intensive treatment of severe Class 11 malocclusions with a headgear-Herbst appliance in the early mixed dentition. AM J ORTHOD 1984;86:1-13. 31. Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance. AM J ORTHOD 1979;76:423-43. 32. Wieslander L. Long-term effect of treatment with the headgear-Herbst appliance in the early mixed dentition. Stability or relapse? AM J ORTHOD DENTOFAC ORTHOP 1993;104: 319-29. Reprint requests to:
Dr. Anthony A. Gianelly Boston University Goldman School of Graduate Dentistry Department of Orthodontics 100 E. Newton St. Boston, MA 02118-2392
T h e r e are few more compelling and controversial issues in orthodontics than the "timing" of treatment of the various problems encountered in growing patients. Most often, the principal concern is the benefit of treatment in the deciduous early mixed dentition stage of development when compared with treatment started in the late mixed dentition stage of development or in the permanent dentition. One reason for the controversy is that the accepted "cost" of an early treatment time is a two-phase protocol. Phase 1 generally involves 6 to 12 months of active treatment with the intent to change skeletodental relationships. Phase 2 is the "finishing" process after the eruption of appropriate permanent teeth. Thus, risk/reward analysis becomes inevitable. Do the benefits of early intervention justify the cost of two-phase treatment? Two recent reports are of interest to define the scope of the problem. The Journal of Clinical Orthodontics survey of diagnosis and therapeutics noted that approximately 25% of all patients are treated in a two-phase manner.' The AAO May Bulletin indicated that approximately 1.3 million persons in 1992 elected orthodontic treatment. At 25% penetration, at least 300,000+ patients are in a twophase treatment program. There are only 900,000+ growing patients since adults comprise 20% to 25% of the patient population.' Essentially, a third of all children are treated in two phases. The premise of this article is that at least 90% of all growing patients can be treated successfully in only one phase by starting treatment in the late mixed dentition stage of development-identified by the exfoliation of all deciduous teeth except the deciduous second molars or the "E"s. Implicit in this view is that there are few, if any, benefits that are unique to and dependent on earlier treatment. Also implicit is that habit control, the use of passive appliances such as space maintainers and minor alignment of incisors for esthetic or trauma reasons, is not considered part of conventional twophase treatment. ~Professor and Chairman, Department of Orthodontics, Boston University School of Graduate Dentistry. AM J ORTHOD DENTOFAC ORTHOP 1995;1118:556~9. Copyright © 1995 by the American Association of Orthodontists. 0889-5406/95/$5.00 + 0 8/1/60751
556
The other 5% to 10% of patients includes those with crossbites complicated by a mandibular shift and certain patients with Class III malocclusions who could benefit from immediate resolution of the problem. Consider the correction of the two most common orthodontic problems: crowding in either Class I or Class II malocclusions and the correction of Class II malocclusions. Crowding." Since lower arch conditions generally determine the course of treatment, only the changes in the lower arch will be discussed. The leeway space can provide adequate space to accommodate an aligned dentition in the vast majority of patients. 2 For example, an evaluation of the mandibular models of 100 patients in the mixed dentition stage of development revealed that 85 of the 100 subjects demonstrated crowding, which averaged between 4 to 5 ram. However, 62 (73%) of these 85 patients with crowding had sufficient space to align the teeth when the leeway space gain was included in the analysis. Thus, crowding can be resolved in 73% of patients with crowding in the mixed dentition stage of development simply by preserving and using the leeway space. (Since the combined mesiodistal diameters of the deciduous canine and first molar are essentially the same as the mesiodistal diameters of the permanent canine and first premolar, ~ the space gain, in actuality, represents the "E" space.) Maintaining the "E" space can readily be accomplished by starting treatment in the late mixed dentition stage. One exception might be the placement of a passive lingual arch to preserve arch length when a deciduous canine is lost prematurely. In the 100 patients evaluated, the nonextraction rate for alignment purposes would be 77% when the 15 patients who have no crowding in the mixed dentition stage are included. In 7 of the remaining 23 patients, the crowding did not exceed 2 mm; whereas in 16 patients, the crowding, even after "E" space preservation, exceeded 2 ram. A more aggressive nonextraction approach, which has been recommended, is to start treatment at an earlier age to "develop" the lower arch by using force systems that will lead to active and/or passive expansion of the arch. 4 Two common sys-
American Journal of 01~hodontics and Dento)acial Orthopedics Volume 108, No. 5
tems for this purpose are the use of a lip bumper and rapid palatal expansion (RPE) treatment to induce spontaneous expansion of the lower arch as the maxillary arch widens, The lip bumper can gain space since both arch length and width generally increase after lip bumper placement. 57 However, in view of the report by Little et al. s that the largest amount of postretention irregularity of any group studied was noted in a group of mixed dentition patients whose treatment involved more than 1 mm of arch length expansion, it seems prudent to limit the lip bumper to a 1 mm increase in arch length. This can generally be accomplished if lip bumper treatment begins after the eruption of the first premolar. Specifically, Bergersen indicated that a 1 mm gain in arch length is fairly common after 3 to 6 months of lip bumper therapy. 7 Since a 1 mm gain of arch length would reduce 2 mm of crowding, this late mixed dentition treatment would resolve the crowding in the seven patients with 2 mm or less of crowding. Therefore, with treatment that could be started in the late mixed dentition stage of development, the teeth can be aligned in 84% of the patients in this sample by nonextraction procedures. Would earlier intervention with R P E "develop" the lower arch sufficiently to avoid extractions? 9 In the transverse dimension, a focal point is the expansion of the intercanine width because this increase provides more space for alignment than any other transverse change. Germane et al. '° determined that 1 mm of intercanine expansion produces a 0.73 mm increase in arch perimeter, whereas a l mm expansion of the molars produces only a 0.27 mm increase. There are two studies that are relevant. Sandstrom et al. '~ noted only a 1.1 mm postretention increase in mandibular intercanine dimension in 28 patients whose maxillae were expanded orthopedically. Adkins et al. '2 found, at most, only 0.8 mm lower arch expansion incident to RPE. Thus neither investigation provides optimistic evidence that the lower intercanine dimension will expand more than 1 mm when the maxilla is orthopedically expanded. The transverse dimension of the arch can also be expanded actively. On presumption is that expansion performed at an earlier age might be stable. Since there is no suture, '3 any expansion is dental in nature. Again there are two studies to consider. Lutz and Poulton '4 evaluated the transverse changes that occurred in 13 patients whose lower arch was
Gianelly
557
expanded in the deciduous dentition stage of development and compared these changes to those observed in 12 control subjects. Expansion was accomplished with removable appliances in 11 patients and with fixed appliances in the remaining 2 patients. After a 3-year retention period, the patients were followed for another 3 years. At this time, there was no difference in intercanine dimension between the groups, indicating total relapse of the treatment gain. The relapse of intercanine expansion noted in this study reinforces the findings in the vast majority of investigations that have verified the instability of intercanine expansion in the mandibular arch. ~-~-23 In contrast, Crozat appliances were used to expand the transverse dimension of the lower arch in 5- to 6-year-old patients and retained the changes until all the deciduous teeth exfoliated. 24 After retention was discontinued, the arches remained stable. In this study, there were no control subjects, and data from published sources were used to represent the controls. As such, the actual net expansion (treatment change-growth change) was not reported. At best, by extrapolation, it appeared to approximate 2 to 3 mm. In summary, crowding can be resolved readily in up to 84% of all patients with treatment that need be started no earlier that the late mixed dentition stage of development because the space necessary for alignment in most patients with crowding is gained principally by " E " space control. (To reiterate, the main exception is the placement of a lingual arch). Should the other 16% of the patients be treated earlier than the late mixed dentition stage of development to pursue a nonextraction approach more aggressively? Those who support this view imply that earlier treatment can produce unique results specific to early intervention and these changes can avoid extractions. However, the previously cited evidence indicates that there are no substantial unique benefits related to earlier intervention. In addition, the stability of procedures that are designed to avoid extraction by developing the arches has not been established. The only available study in which the stability of expansion procedures performed in the mixed dentition stage of development is not encouraging since, as mentioned previously, the investigators noted more posttreatment instability when compared with other groups they had examined, s This conclusion is supported by the findings of Glenn et al.: 23 Stability of nonextraction treatment was associated with lower arch dimen-
558
Gianelly
sions that were effectively not expanded during treatment. In their sample, intercanine dimension was 25.4 mm before treatment and 26.0 mm after treatment. Arch length initially was 60.0 ram, and after treatment, it was 60.2 ram. Also, arch development that involves transverse expansion of the intercanine dimension is contrary to the vast majority of available data that document the futility of intercanine expansion. ~5-23 Accordingly, the burden to verify the stability of lateral expansion when performed at an early age is placed on those who propose this strategy. If extraction treatment (which the author prefers) is selected for this group of patients, should they be treated according to a serial extraction protocol, and does this not constitute two-phase treatment? The serial extraction decision, which is complex, does not usually involve active treatment. The first phase, traditionally, is a diagnostic-observation phase with no appliance placement. As such, there is no "protracted treatment time" price to pay. Class H malocclusions: If treatment is started in the late mixed dentition stage of development, at least 90% of all children with Class II malocclusions with or without crowding can be treated successfully in one phase, which lasts between 2 and 3 years. There are a number of procedures used to correct these problems and all function well at this age. For example, one method of correction involves the distal movement of the maxillary molars to convert the Class II malocclusion to a Class I spacing problem. This movement is routinely successful at this age because molars can be moved distally 1 to 2 mm per month during this time period, -~5"26 and mandibular growth is apparently sufficient to aid in correcting the Class I! malocclusion. In addition, continuous acting force systems that are not cooperation dependent have been developed 27 to overcome the compliance problem of extraoral appliances. This means that Class II molar relationships can be converted to Class I in 4 to 6 months with little difficulty. Accordingly, earlier intervention is not necessary. As an example, after 3 to 4 months of treatment with continuous extraoral forces, Armstrong noted between 4 to 7 mm of distal movement of the molars in patients in the late mixed dentition stage of development. 25 He also observed an apparent age dependency related to distal molar movement and stated that the "clinical response in the early permanent dentition to continuous extraoral force has not proved rapid enough to justify full time wear of the appli-
American Journal of Orthodontics and DentoJhcial Orthopedics November 1995
ance." This observation reinforces the view that appropriate time to start treating patients with Class II malocclusions is the late mixed dentition stage of development. There is a concern that earlier intervention with extraoral appliances might obtain more of a maxillary orthopedic effect that would be important for patients with maxillary prognathism. Unfortunately, the information is inadequate to support a conclusion. In one study, Wieslander compared the results of extraoral appliance use in patients in the early and late mixed dentition and noted a 1 mm greater orthopedic effeCt in the younger group? 8 The "cost" of the 1 mm is two-phase treatment (which, to me, is not a useful cost/benefit ratio.) For patients with Class II malocclusions characterized by mandibular retrognathism, use of functional appliances, with the intent to stimulate mandibular growth, has been advocated. 4 The appropriate time for optimal use of these appliances is not clear. McNamara et al. 2~ demonstrated an age dependent mandibular growth response with the use of the functional regulator-2 appliance when they recorded more mandibular growth in patients who were older than 10.5 years in comparison with the mandibular growth noted in younger patients. In their study, they divided patients according to age into a younger group (less than 10.5 years) and an older group (greater than 10.5 years) and observed 3.2 mm/year mandibular growth in the younger group compared with 4.0 mm/year in the older patients. Thus the mandibular response favored later intervention. The mandibular growth response noted with the Herbst appliance does not appear to be age dependent. 3°'31 For instance, Wieslander treated a group of 8- to 9-year-old patients and recorded 3.4 mm of mandibular growth after 5 months of treatment with the Herbst appliance?" Pancherz, whose patients were 10 to 11 years old, also noted 3.2 mm of mandibular growth after 6 months of Herbst therapy? ~Again, the mandibular response does not justify early intervention. Wieslander also attempted to achieve the "best of both orthopedic worlds" by intensive phase 1 treatment of young patients with combined application of an extraoral and a Herbst appliance. The protrusions were reduced rapidly, and the profiles straightened in phase 1. However, the pause between phase 1 and phase 2 became a problem since overjet reappeared in a number of patients. This led to a prolonged retention phase that extended beyond 3 years in some instances? 2
American Journal oJ' Orthodontics and DentoJhcial Orthopedics Volume 108, No. 5
When these patients and a control group were evaluated 8 to 9 years later, there was no statistical difference in mandibular length and forward position of the mandible. 32 This experience brings the cost/benefit issue into sharp focus. Are children with common problems gaining adequate benefits to justify the time and expense incurred with two-phase treatment? The proposal supported in this treatise is that for more than 90% of the patients, essentially all treatment goals can be accomplished in one phase of treatment when treatment is started in the late mixed dentition stage of development. REFERENCES 1. Gottlieb EL, Neslon AH, Vogels IlI DS. 1990 study of orthodontic diagnosis and treatment procedures. Part 2. J Clin Orthod 1991;25:223-30. 2. Arnold S. Analysis of leeway space in the mixed dentition. [Thesis.] Boston: Boston University, 1991. 3. Moyers RE, van der Linden FPGM, Riolo ML, McNamara JA Jr. Standards of human occlusal development. Monograph 5. Craniofacial Growth Series. Ann Arbor: Center of Human Development, The University of Michigan, 1976. 4. McNamara JA Jr, Brudon WL. Orthodontic and orthopedic treatment in the mixed dentition. Ann Arbor: Needham Press, 1993. 5. Nevant CT, Buschang PH, Alexander RG, Steffan JM. Lip bumper therapy for gaining arch length. AM J ORTHOD DENTOFAC ORTHOP 1991;100:330-6. 6. Osborne WS, Nanda RS, Currier GF. Mandibular arch perimeter changes wit h lip bumper treatment. AM J ORTHOD DENTOFAC ORTHOP 1991;99:527-32. 7. Bergersen EO. A cephalometric study of the clinical use of the mandibular labial bumper. AM J ORTHOD 1972;61:578602. 8. Little RM, Reidel RA, Stein A. Mandibular arch length increase during the mixed dentition: postretention evaluation of stability and relapse. AM J ORTHOD DENTOFAC ORTHOP 1990;97:393-404. 9. Haas A. Long-term post-treatment evaluation of rapid palatal expansion. Angle Orthod 1980;50:189-217. 10. Germane N, Lindauer SJ, Rubenstein LK, Rever JH, Isaacson RJ. Increase in arch perimeter due to orthodontic expansion. AM J ORTHOD DENTOFAC ORTHOP 1991;100: 421-7. 11. Sandstrom RA, Klapper L, Papaconstantinou S. Expansion of the lower arch concurrent with rapid maxillary expansion. AM J ORTHOD DENTOFAC ORTHOP 1988;94:296-302. 12. Adkins MA, Nanda RS, Currier GF. Arch perimeter changes on rapid palatal expansion. AM J ORTHOD DENTOFAC ORTHOP 1990;97:194-9. 13. Burstone CJ. Perspective on orthodontic stability. In: Nanda R, Burstone CJ, eds. Retention and stability in orthodontics. Philadelphia: WB Saunders;1993:52. 14. Lutz HD, Poulton DR. Stability of dental arch expansion in the deciduous dentition. Angle Orthod 1985;55:299-315.
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15. Peak JD. Cuspid stability. AM J ORTHOD 1956;42:608-14. 16. Bishara SE, Chada JM, Potter RB. Stability of intercanine width, overbite, and overjet correction. AM J ORTHOD 1973;63:588-95. 17. Shapiro PA. Mandibular dental arch form and dimension. AM J ORTHOD 1974;66:58-70. 18. Kuftinec MM. Effect of edgewise treatment and retention of mandibular incisors. AM J ORTHOD 1975;68:316-22. 19. El-Mangoury NH. Orthodontic relapse in subjects with varying degrees of anteroposterior and vertical dysplasia. AM J ORTHOD 1979;75:548-61. 20. Sondhi A, Cleall JF, BeGole EA. Dimensional changes in the arches of orthodontically treated cases. AM J ORTHOD 1986;77:60-74. 21. Little RM, Wallen TR, Reidel RA. Stability and relapse of mandibular anterior alignment-first premolar extraction cases treated by conventional edgewise orthodontics. AM J ORTHOD 1981;80:349-65. 22. Uhde MD, Sadowsky (2, BeGole EA. Long-term stability of dental relationships after orthodontic treatment. Angle Orthod 1983;53:240-52. 23. Glenn G, Sinclair PM, Alexander RG. Nonextraction orthodontic therapy: posttreatment dental and skeletal stability. AM J ORTHOD DENTOFAC ORTHOP 1987;92:321-28. 24. Mclnaney JB, Adams RM, Freeman MM. A nonextraction approach to crowded dentitions in young children: early recognition and treatment. J Am Dent Assoc 1980;101: 251-7. 25. Armstrong MM. Controlling the magnitude duration and direction of extraoral force. AM J ORTHOD 1971;59:217-43. 26. Bernstein L, Ulbrich R, Gianelly AA. Orthopedics versus orthodontics in Class II treatment. AM J ORTHOD 1977;72: 549-59. 27. Gianelly AA, Bednar J, Dietz VS. Japanese NiTi coils used for molar distal movement. AM J ORTHOD DENTOFAC ORTHOP 1991;99:564-6. 28. Wieslander L. Early or late cervical traction therapy of Class II malocclusions in the mixed dentition. AM J ORTHOD 1975;67:432-9. 29. McNamara JA Jr, Bookstein FL, Shaughnessy TG. Skeletal and dental relationships following functional regulator therapy on Class II patients. AM J ORTHOD 1985;88:91-109. 30. Wieslander L. Intensive treatment of severe Class 11 malocclusions with a headgear-Herbst appliance in the early mixed dentition. AM J ORTHOD 1984;86:1-13. 31. Pancherz H. Treatment of Class II malocclusions by jumping the bite with the Herbst appliance. AM J ORTHOD 1979;76:423-43. 32. Wieslander L. Long-term effect of treatment with the headgear-Herbst appliance in the early mixed dentition. Stability or relapse? AM J ORTHOD DENTOFAC ORTHOP 1993;104: 319-29. Reprint requests to:
Dr. Anthony A. Gianelly Boston University Goldman School of Graduate Dentistry Department of Orthodontics 100 E. Newton St. Boston, MA 02118-2392