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Maxillary Deficiency Syndrome
CHAPTER
12
Maxillary Deficiency Syndrome James A. McNamara, Jr.
O
ne of the major concepts that has emerged during the author’s 40+ years of clinical practice in ortho dontics concerns the diagnosis and treatment of what can be termed maxillary deficiency syndrome.1 In fact, maxillary transverse and/or sagittal deficiency may be one of the most pervasive skeletal problems in the craniofacial region, especially in patients of European ancestry. Many of the individual characteristics or symptoms of this condition have been well recognized in orthodontics, but rarely are they combined conceptually. However, it may be possible to produce a greater treatment effect on the skeletal struc tures of the maxillary complex than in the mandible, parti cularly with regard to the management of the transverse dimension.
MANIFESTATIONS OF MAXILLARY TRANSVERSE DEFICIENCY The manifestations of maxillary transverse deficiency are encountered by the orthodontist on a daily basis, but usually they are not quantified. As part of an initial evalu ation of a patient, it is recommended that the distance between the closest points of the maxillary first molars (i.e., transpalatal width) be measured2 (Fig. 12-1). Typi cally, a maxillary arch with a transpalatal width of 35 to 39 mm can accommodate a dentition of average size without crowding or spacing. However, maxillary arches less than 31 mm in transpalatal width may be crowded and thus in need of orthopedic expansion in growing individu als or surgically assisted expansion in adults.3 Other factors that must be considered when making the extraction/ expansion decision include facial type, soft tissue profile, and level of muscle tonus.
Transverse Skeletal Imbalances A major conceptual leap is from using rapid maxillary expansion (RME) in the correction of posterior crossbite to using RME in patients without crossbite. Orthodontists tradition ally have used RME to correct posterior crossbites, but little else. In contrast to the aggressive approaches often taken in treating skeletally based anteroposterior and vertical prob lems,4-8 many orthodontists have been reluctant to change arch dimensions transversely. However, the transverse dimension of the maxilla may be the most adaptable of all the regions of the craniofacial complex. Many, if not most, transverse skeletal imbalances in the maxilla are ignored or simply not recognized, and thus the treatment options for such patients are necessarily more limited than if these imbalances were considered.
Crowding and Protrusion Other than crossbite, two of the most common problems encountered by the orthodontist are crowding (Fig. 12-2, A) and protrusion (Fig. 12-2, B) of the teeth, both of which result from discrepancies between the size of the teeth and the size of the bony bases. Howe et al.3 have shown that dental crowding appears to be related more to a deficiency in arch perimeter than to teeth that are too large. A primary factor in dental crowding often is maxillary transverse and/ or sagittal deficiency. If the position of the maxillary denti tion reflects the skeletal discrepancy, crossbite results; on the other hand, if maxillary constriction is camouflaged by the dentition, and both dental arches are constricted, crowding in the absence of crossbite is observed.
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Part II Clinical Management of Sagittal and Vertical Discrepancies
It is well recognized that one of the limiting factors in the management of tooth-size/arch-size problems is available space in the mandibular dental arch. Unfortunately, true orthopedic expansion of the lower arch is not possible, unless recently developed distraction osteogenesis tech niques are used. Interestingly, it has been the author’s obser vation that the position of the mandibular dentition may be influenced more by maxillary skeletal morphology than by the size and shape of the mandible.9 For example, after RME in the mixed dentition, there is not only expansion of the maxillary dental arch with the acrylic splint expander (Fig. 12-3), but also subsequent spontaneous widening of the lower dental arch in some patients after expansion. In other patients with constricted mandibular dentitions and crowd ing of the lower incisors, the author often uses a removable lower Schwarz expansion appliance (Fig. 12-4) to upright the lower posterior teeth that have erupted into occlusion in a more lingual orientation because of the associated constricted maxilla. Widening the mandibular dental arch
Fig. 12-1 Transpalatal width is measured from the closest points on the lingual surfaces on the maxillary first molars. Normal transpalatal width is 35 to 39 mm in the permanent dentition and 33 to 35 mm in the mixed dentition.
orthodontically before expanding the maxilla orthopedically allows for greater widening of the maxilla by “decompensat ing” the positions of the mandibular teeth (Figs. 12-5 and 12-6).
Other Clinical Signs of Maxillary Deficiency Crossbite and dental crowding are two easily recognizable clinical signs that could be the result of maxillary deficiency. Other effects of maxillary deficiency, however, are not as easily identifiable and often not detected. For example, later ally flared maxillary posterior teeth (Fig. 12-7) may camou flage a maxillary skeletal transverse deficiency. These patients have what appears to be a normal posterior occlusion, although on closer inspection the maxilla is narrow (e.g., intermolar width <31 mm), and the curve of Wilson is accentuated. The lingual cusps of the maxillary posterior teeth extend below the occlusal plane, often leading to bal ancing interferences during function. Even though there is no crossbite, such patients are candidates for RME before comprehensive edgewise therapy. Another clinical manifestation of maxillary deficiency is dark spaces at the corner of the mouth (Fig. 12-8). Vanarsdall10 has used the term “negative space” to refer to the shadows that occur in the corners of the mouth during smiling in some patients having a narrow, tapered maxilla and a mesofacial or brachyfacial skeletal pattern. Regardless of whether teeth are extracted, the maxilla can be widened by means of RME, increasing transpalatal width and elimi nating or reducing the dark spaces in the “buccal corridors.” This type of orthopedic intervention results in what many consider a more pleasing frontal facial appearance. Using RME for esthetic purposes (e.g., “broadening the smile”) will become an increasingly recognized indication for RME in patients with narrow dental arches.
CLASS III MALOCCLUSIONS It is not surprising that certain types of sagittal malocclu sions also are associated with maxillary deficiency. One of the major components of Class III malocclusion is maxillary
Fig. 12-2 A, Crowding is a common observation in mixed-dentition patients. This patient pre sented with crowded lower incisors and an unerupted upper-right lateral incisor. B, Protrusion of the maxillary dentition is evident in this patient.
Chapter 12 Maxillary Deficiency Syndrome
skeletal retrusion, a condition that occurs in almost half of all Class III patients.11 The most efficient and effective treat ment for Class III problems in the early mixed dentition appears to be RME (Fig. 12-9) combined with the orthope dic facial mask (Fig. 12-10), although the recent utilization of anchor plates and intermaxillary traction by DeClerck12 shows significant promise in Class III patients with severe anteroposterior problems. In some mixed-dentition patients with only mild skeletal imbalances, however, simply widening the maxilla without initiating facial mask treatment may lead to a spontaneous correction of anterior crossbite and the resolution of the Class III molar relationship.13 In patients with more severe problems, modest maxillary skeletal advancement combined with a similar amount of maxillary dentoalveolar advance ment can be induced by RME combined with facial mask therapy.14-16 The most common surgical treatment for this condition in the mature patient at present is the LeFort I osteotomy, a procedure during which the maxilla can be both advanced and widened, instead of reliance on surgical procedures that involve the mandible.
139
relationship of the posterior dentition usually has a 3-mm to 5-mm transverse discrepancy between the maxilla and mandible. It appears that most Class II malocclusions in mixeddentition patients are associated with maxillary constriction. When a clinician is initiating treatment in the mixed denti tion, the first step in the treatment of mild to moderate Class II malocclusions, characterized at least in part by mild man dibular skeletal retrusion and maxillary constriction (e.g., intermolar width ≤30 mm in the early mixed dentition), should be orthopedic expansion of the maxilla. The maxil lary posterior teeth can be left in an overexpanded position, with contact still being maintained between the upper lingual cusps and the buccal cusps of the lower posterior teeth.2 The occlusion subsequently is stabilized using a removable palatal
CLASS II MALOCCLUSIONS Counterintuitively, certain Class II malocclusions also may be associated with maxillary deficiency. From a sagittal per spective, maxillary skeletal protrusion occurs only in about 5% to 10% of Class II patients of European ancestry, whereas as many as 30% of Class II patients may have maxillary skeletal retrusion, often associated with an obtuse nasolabial angle and a steep mandibular plane angle.16 Further, many Class II malocclusions, when evaluated clinically, have no obvious maxillary transverse constriction. When the study models of the patient are “hand-articulated” into a Class I canine relationship, however, a unilateral or bilateral cross bite results. In fact, Tollaro et al.17 have shown that a Class II patient with what appears to be a normal buccolingual
Fig. 12-3 An acrylic splint expander that is bonded to the maxil lary posterior teeth is the appliance of choice in the mixed-denti tion patient with a narrow maxilla. (Modified from McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-4 Lower removable Schwarz appliance. A, After initial placement. B, After 5 months of active treatment. The lower posterior teeth have been uprighted, and a modest amount of arch space has been gained in the lower anterior region. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
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Part II Clinical Management of Sagittal and Vertical Discrepancies
Fig. 12-7 Maxillary constriction can lead to an accentuated
Fig. 12-5 Lateral bialveolar constriction. Frontal view of a patient with maxillary constriction whose mandibular molars, instead of erupting into a posterior crossbite relationship (dashed lines), have erupted lingually. The buccal occlusion appears normal, and no crossbite is evident. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
curve of Wilson (W). When this condition exists, the lingual cusps hang down, often leading to balancing interferences. A flat occlusal plane (OP) often is a treatment objective. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-8 Maxillary constriction can be evidenced by black spaces appearing at the corners of the mouth during smiling. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-6 A lower Schwarz appliance can be used to upright the lower dentition, producing a tendency toward a posterior crossbite. The maxilla subsequently can be expanded further because the mandibular dental arch has been widened initially. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
plate in the mixed dentition or, alternatively, full orthodon tic appliances combined with a transpalatal arch in the per manent dentition.
Spontaneous Correction of Class II Malocclusion An interesting (and somewhat surprising) observation fol lowing initial efforts to expand Class II patients in the early mixed dentition was the occurrence of a spontaneous cor rection of the Class II malocclusion during the retention
period. Such patients had either an end-to-end or full-cusp Class II molar relationship. Generally, these patients did not have severe skeletal imbalances but typically were character ized clinically as having either mild-to-moderate mandibu lar skeletal retrusion or an orthognathic facial profile. At the time of expander removal, these patients had a strong ten dency toward a buccal crossbite with only the lingual cusps of the upper posterior teeth contacting the buccal cusps of the lower posterior teeth. After expander removal, a maxil lary maintenance plate was used for stabilization. Several appointments later, the tendency toward a buccal crossbite often disappeared, and some of the patients now had a solid Class I occlusal relationship. It should be noted that the shift in molar relationship in these patients occurred before the transition from the lower second deciduous molars to the lower second premolars, the point at which an improvement in Angle classification some times occurs in untreated subjects because of the forward movement of the lower first molars into the leeway space.
Chapter 12 Maxillary Deficiency Syndrome
A large prospective clinical study18 of full-cusp and endto-end Class II patients treated with early orthopedic expan sion of the maxilla from the author’s private-practice database currently is underway. The initial analysis of the serial lateral cephalograms of these patients indicates that a spontaneous improvement in Class II molar relationship is a common occurrence. This spontaneous correction has forced us to rethink our approach to Class II molar correction treatment. Tradition ally, clinicians have viewed a Class II malocclusion as pri marily a sagittal and vertical problem. Experience with the post-RME correction of the Class II problem in growing patients indicates that many Class II malocclusions have a strong transverse component. The overexpansion of the maxilla, which subsequently is stabilized with a removable palatal plate, disrupts the occlusion. The patient apparently becomes more inclined to position the jaw slightly forward,19 thus eliminating the tendency toward a buccal crossbite and at the same time improving the sagittal occlusal relationship. Presumably, subsequent growth and remodeling of the structures of the temporomandibular joint make this initial postural change permanent. Spontaneous Class II correction, if it is going to occur, usually happens during the first 6 to 12 months of the postRME period. The Class II correction can be enhanced further at the end of the mixed-dentition period by way of a transpalatal arch that not only maintains the maxillary leeway space, but also can be activated sequentially to produce molar rotation and uprighting.2 At this point, if the occlusion still has a Class II component, additional treat ment approaches may be indicated (e.g., functional jaw orthopedics, Forsus appliance, Class II elastics). The phenomenon of spontaneous correction after RME treatment combined with routine use of a transpalatal arch is now part of our mixed-dentition treatment protocol. We have found that the need for subsequent functional jaw orthopedics has decreased substantially in our practice during the last decade.
CONCLUSION The various orthodontic problems discussed in this chapter are all linked to maxillary deficiency in the transverse or the sagittal dimension, or in both. Signs of maxillary deficiency include much more than anteroposterior crossbite and crowding of the maxillary dentition. Signs of maxillary defi ciency often appear together in maxillary deficiency syn drome. A proven orthopedic appliance, the rapid maxillary expander, can be incorporated easily into treatment plans directed toward a variety of orthodontic conditions. RME is useful in correcting both Class II and Class III problems as well as in resolving mild to moderate tooth-size/arch-perim eter discrepancies. In addition, RME can be used to “broaden the smile” while improving nasal airway function in some patients.20 Many or most of these signs appear in the same patient with maxillary deficiency, with rapid maxillary expansion available as an adjunct to fixed-appliance treat
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Fig. 12-9 Facial mask hooks have been added to the acrylic splint expander to allow for the attachment of elastics. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-10 The orthopedic facial mask of Petit often is used in patients with Class III malocclusion. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
ment, a procedure that presumably will be incorporated into orthodontic treatment protocols with increasing frequency in the future.
ACKNOWLEDGMENT This chapter is written to honor Dr. Ram S. Nanda, Profes sor Emeritus and former Chair of the Department of Ortho dontics at the University of Oklahoma. The Nanda family has made important contributions to orthodontics, with his brothers Dr. Ravindra Nanda Chair of Orthodontics at the University of Connecticut and the late Dr. Surender K.
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Nanda a fellow faculty member for many years at the Uni versity of Michigan. It is my pleasure to write this chapter in honor of Dr. Ram Nanda’s significant lifetime contributions to our specialty.
References 1. McNamara JA Jr: Maxillary transverse deficiency, Am J Orthod Dentofacial Orthop 117:567-570, 2000. 2. McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press. 3. Howe RP, McNamara JA Jr, O’Connor KA: An examination of dental crowding and its relationship to tooth size and arch dimension, Am J Orthod 83:363-373, 1983. 4. Toth LR, McNamara JA Jr: Treatment effects produced by the twin block appliance and the FR-2 appliance of Fränkel com pared to an untreated Class II sample, Am J Orthod Dentofacial Orthop 116:597-609, 1999. 5. Burkhardt DR, McNamara JA Jr, Baccetti T: Maxillary molar distalization or mandibular enhancement: a cephalometric comparison of the Pendulum and Herbst appliances, Am J Orthod Dentofacial Orthop 123:108-116, 2003. 6. Freeman DC, McNamara JA Jr, Baccetti T, Franchi L: Longterm treatment effects of the FR-2 appliance of Fränkel, Am J Orthod Dentofacial Orthop (in press). 7. Freeman CS, McNamara JA Jr, Baccetti T, Franchi L: Treat ment effects of the Bionator and high-pull facebow combina tion followed by fixed appliances in patients with increased vertical dimension, Am J Orthod Dentofacial Orthop 131:184195, 2007. 8. Schulz SO, McNamara JA Jr, Baccetti T, Franchi L: Treatment effects of bonded RME and vertical pull chin cup followed by fixed appliances in patients with increased vertical dimension, Am J Orthod Dentofacial Orthop 128:326-336, 2005. 9. McNamara JA Jr: The role of the transverse dimension in orthodontic diagnosis and treatment, Monograph 36, Craniofacial
Growth Series, Ann Arbor, 1999, Center for Human Growth and Development, University of Michigan. 10. Vanarsdall RL Jr: Personal communication, 1992. 11. Guyer EC, Ellis E, McNamara JA Jr, Behrents RG: Components of Class III malocclusion in juveniles and adolescents, Angle Orthod 56:7-30, 1986. 12. DeClerck H: Unpublished data, 2007. 13. McNamara JA Jr: An orthopedic approach to the treatment of Class III malocclusion in young patients, J Clin Orthod 21:598608, 1987. 14. McGill JS, McNamara JA Jr: Treatment and post-treatment effects of rapid maxillary expansion and facial mask therapy. In McNamara JA Jr, editor. Growth modification: what works, what doesn’t and why, Monograph 36, Craniofacial Growth Series, Center for Human Growth and Development, Ann Arbor, 1999, University of Michigan. 15. Westwood PV, McNamara JA Jr, Baccetti T, et al: Long-term effects of early Class III treatment with rapid maxillary expan sion and facial mask therapy, Am J Orthod Dentofacial Orthop 123:306-320, 2003. 16. McNamara JA Jr: Components of Class II malocclusion in children 8-10 years of age, Angle Orthod 51:177-202, 1981. 17. Tollaro I, Baccetti T, Franchi L, Tanasescu CD: Role of posterior transverse interarch discrepancy in Class II, Division 1 maloc clusion during the mixed dentition phase, Am J Orthod Dentofacial Orthop 110:417-422, 1996. 18. Guest SS, McNamara JA Jr, Baccetti T, Franchi L: Improving Class II malocclusion as a “side-effect” of rapid maxillary expansion: a prospective clinical study, Submitted for publica tion, 2008. 19. Wendling LK, McNamara JA Jr, Franchi L, Baccetti T: Short-term skeletal and dental effects of the acrylic splint rapid maxillary expansion appliance, Angle Orthod 75:7-14, 2005. 20. Hartgerink DV, Vig PS, Abbott DW: The effect of rapid maxil lary expansion on nasal airway resistance, Am J Orthod Dentofacial Orthop 92:381-389, 1987.
12
Maxillary Deficiency Syndrome James A. McNamara, Jr.
O
ne of the major concepts that has emerged during the author’s 40+ years of clinical practice in ortho dontics concerns the diagnosis and treatment of what can be termed maxillary deficiency syndrome.1 In fact, maxillary transverse and/or sagittal deficiency may be one of the most pervasive skeletal problems in the craniofacial region, especially in patients of European ancestry. Many of the individual characteristics or symptoms of this condition have been well recognized in orthodontics, but rarely are they combined conceptually. However, it may be possible to produce a greater treatment effect on the skeletal struc tures of the maxillary complex than in the mandible, parti cularly with regard to the management of the transverse dimension.
MANIFESTATIONS OF MAXILLARY TRANSVERSE DEFICIENCY The manifestations of maxillary transverse deficiency are encountered by the orthodontist on a daily basis, but usually they are not quantified. As part of an initial evalu ation of a patient, it is recommended that the distance between the closest points of the maxillary first molars (i.e., transpalatal width) be measured2 (Fig. 12-1). Typi cally, a maxillary arch with a transpalatal width of 35 to 39 mm can accommodate a dentition of average size without crowding or spacing. However, maxillary arches less than 31 mm in transpalatal width may be crowded and thus in need of orthopedic expansion in growing individu als or surgically assisted expansion in adults.3 Other factors that must be considered when making the extraction/ expansion decision include facial type, soft tissue profile, and level of muscle tonus.
Transverse Skeletal Imbalances A major conceptual leap is from using rapid maxillary expansion (RME) in the correction of posterior crossbite to using RME in patients without crossbite. Orthodontists tradition ally have used RME to correct posterior crossbites, but little else. In contrast to the aggressive approaches often taken in treating skeletally based anteroposterior and vertical prob lems,4-8 many orthodontists have been reluctant to change arch dimensions transversely. However, the transverse dimension of the maxilla may be the most adaptable of all the regions of the craniofacial complex. Many, if not most, transverse skeletal imbalances in the maxilla are ignored or simply not recognized, and thus the treatment options for such patients are necessarily more limited than if these imbalances were considered.
Crowding and Protrusion Other than crossbite, two of the most common problems encountered by the orthodontist are crowding (Fig. 12-2, A) and protrusion (Fig. 12-2, B) of the teeth, both of which result from discrepancies between the size of the teeth and the size of the bony bases. Howe et al.3 have shown that dental crowding appears to be related more to a deficiency in arch perimeter than to teeth that are too large. A primary factor in dental crowding often is maxillary transverse and/ or sagittal deficiency. If the position of the maxillary denti tion reflects the skeletal discrepancy, crossbite results; on the other hand, if maxillary constriction is camouflaged by the dentition, and both dental arches are constricted, crowding in the absence of crossbite is observed.
137
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Part II Clinical Management of Sagittal and Vertical Discrepancies
It is well recognized that one of the limiting factors in the management of tooth-size/arch-size problems is available space in the mandibular dental arch. Unfortunately, true orthopedic expansion of the lower arch is not possible, unless recently developed distraction osteogenesis tech niques are used. Interestingly, it has been the author’s obser vation that the position of the mandibular dentition may be influenced more by maxillary skeletal morphology than by the size and shape of the mandible.9 For example, after RME in the mixed dentition, there is not only expansion of the maxillary dental arch with the acrylic splint expander (Fig. 12-3), but also subsequent spontaneous widening of the lower dental arch in some patients after expansion. In other patients with constricted mandibular dentitions and crowd ing of the lower incisors, the author often uses a removable lower Schwarz expansion appliance (Fig. 12-4) to upright the lower posterior teeth that have erupted into occlusion in a more lingual orientation because of the associated constricted maxilla. Widening the mandibular dental arch
Fig. 12-1 Transpalatal width is measured from the closest points on the lingual surfaces on the maxillary first molars. Normal transpalatal width is 35 to 39 mm in the permanent dentition and 33 to 35 mm in the mixed dentition.
orthodontically before expanding the maxilla orthopedically allows for greater widening of the maxilla by “decompensat ing” the positions of the mandibular teeth (Figs. 12-5 and 12-6).
Other Clinical Signs of Maxillary Deficiency Crossbite and dental crowding are two easily recognizable clinical signs that could be the result of maxillary deficiency. Other effects of maxillary deficiency, however, are not as easily identifiable and often not detected. For example, later ally flared maxillary posterior teeth (Fig. 12-7) may camou flage a maxillary skeletal transverse deficiency. These patients have what appears to be a normal posterior occlusion, although on closer inspection the maxilla is narrow (e.g., intermolar width <31 mm), and the curve of Wilson is accentuated. The lingual cusps of the maxillary posterior teeth extend below the occlusal plane, often leading to bal ancing interferences during function. Even though there is no crossbite, such patients are candidates for RME before comprehensive edgewise therapy. Another clinical manifestation of maxillary deficiency is dark spaces at the corner of the mouth (Fig. 12-8). Vanarsdall10 has used the term “negative space” to refer to the shadows that occur in the corners of the mouth during smiling in some patients having a narrow, tapered maxilla and a mesofacial or brachyfacial skeletal pattern. Regardless of whether teeth are extracted, the maxilla can be widened by means of RME, increasing transpalatal width and elimi nating or reducing the dark spaces in the “buccal corridors.” This type of orthopedic intervention results in what many consider a more pleasing frontal facial appearance. Using RME for esthetic purposes (e.g., “broadening the smile”) will become an increasingly recognized indication for RME in patients with narrow dental arches.
CLASS III MALOCCLUSIONS It is not surprising that certain types of sagittal malocclu sions also are associated with maxillary deficiency. One of the major components of Class III malocclusion is maxillary
Fig. 12-2 A, Crowding is a common observation in mixed-dentition patients. This patient pre sented with crowded lower incisors and an unerupted upper-right lateral incisor. B, Protrusion of the maxillary dentition is evident in this patient.
Chapter 12 Maxillary Deficiency Syndrome
skeletal retrusion, a condition that occurs in almost half of all Class III patients.11 The most efficient and effective treat ment for Class III problems in the early mixed dentition appears to be RME (Fig. 12-9) combined with the orthope dic facial mask (Fig. 12-10), although the recent utilization of anchor plates and intermaxillary traction by DeClerck12 shows significant promise in Class III patients with severe anteroposterior problems. In some mixed-dentition patients with only mild skeletal imbalances, however, simply widening the maxilla without initiating facial mask treatment may lead to a spontaneous correction of anterior crossbite and the resolution of the Class III molar relationship.13 In patients with more severe problems, modest maxillary skeletal advancement combined with a similar amount of maxillary dentoalveolar advance ment can be induced by RME combined with facial mask therapy.14-16 The most common surgical treatment for this condition in the mature patient at present is the LeFort I osteotomy, a procedure during which the maxilla can be both advanced and widened, instead of reliance on surgical procedures that involve the mandible.
139
relationship of the posterior dentition usually has a 3-mm to 5-mm transverse discrepancy between the maxilla and mandible. It appears that most Class II malocclusions in mixeddentition patients are associated with maxillary constriction. When a clinician is initiating treatment in the mixed denti tion, the first step in the treatment of mild to moderate Class II malocclusions, characterized at least in part by mild man dibular skeletal retrusion and maxillary constriction (e.g., intermolar width ≤30 mm in the early mixed dentition), should be orthopedic expansion of the maxilla. The maxil lary posterior teeth can be left in an overexpanded position, with contact still being maintained between the upper lingual cusps and the buccal cusps of the lower posterior teeth.2 The occlusion subsequently is stabilized using a removable palatal
CLASS II MALOCCLUSIONS Counterintuitively, certain Class II malocclusions also may be associated with maxillary deficiency. From a sagittal per spective, maxillary skeletal protrusion occurs only in about 5% to 10% of Class II patients of European ancestry, whereas as many as 30% of Class II patients may have maxillary skeletal retrusion, often associated with an obtuse nasolabial angle and a steep mandibular plane angle.16 Further, many Class II malocclusions, when evaluated clinically, have no obvious maxillary transverse constriction. When the study models of the patient are “hand-articulated” into a Class I canine relationship, however, a unilateral or bilateral cross bite results. In fact, Tollaro et al.17 have shown that a Class II patient with what appears to be a normal buccolingual
Fig. 12-3 An acrylic splint expander that is bonded to the maxil lary posterior teeth is the appliance of choice in the mixed-denti tion patient with a narrow maxilla. (Modified from McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-4 Lower removable Schwarz appliance. A, After initial placement. B, After 5 months of active treatment. The lower posterior teeth have been uprighted, and a modest amount of arch space has been gained in the lower anterior region. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
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Fig. 12-7 Maxillary constriction can lead to an accentuated
Fig. 12-5 Lateral bialveolar constriction. Frontal view of a patient with maxillary constriction whose mandibular molars, instead of erupting into a posterior crossbite relationship (dashed lines), have erupted lingually. The buccal occlusion appears normal, and no crossbite is evident. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
curve of Wilson (W). When this condition exists, the lingual cusps hang down, often leading to balancing interferences. A flat occlusal plane (OP) often is a treatment objective. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-8 Maxillary constriction can be evidenced by black spaces appearing at the corners of the mouth during smiling. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-6 A lower Schwarz appliance can be used to upright the lower dentition, producing a tendency toward a posterior crossbite. The maxilla subsequently can be expanded further because the mandibular dental arch has been widened initially. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
plate in the mixed dentition or, alternatively, full orthodon tic appliances combined with a transpalatal arch in the per manent dentition.
Spontaneous Correction of Class II Malocclusion An interesting (and somewhat surprising) observation fol lowing initial efforts to expand Class II patients in the early mixed dentition was the occurrence of a spontaneous cor rection of the Class II malocclusion during the retention
period. Such patients had either an end-to-end or full-cusp Class II molar relationship. Generally, these patients did not have severe skeletal imbalances but typically were character ized clinically as having either mild-to-moderate mandibu lar skeletal retrusion or an orthognathic facial profile. At the time of expander removal, these patients had a strong ten dency toward a buccal crossbite with only the lingual cusps of the upper posterior teeth contacting the buccal cusps of the lower posterior teeth. After expander removal, a maxil lary maintenance plate was used for stabilization. Several appointments later, the tendency toward a buccal crossbite often disappeared, and some of the patients now had a solid Class I occlusal relationship. It should be noted that the shift in molar relationship in these patients occurred before the transition from the lower second deciduous molars to the lower second premolars, the point at which an improvement in Angle classification some times occurs in untreated subjects because of the forward movement of the lower first molars into the leeway space.
Chapter 12 Maxillary Deficiency Syndrome
A large prospective clinical study18 of full-cusp and endto-end Class II patients treated with early orthopedic expan sion of the maxilla from the author’s private-practice database currently is underway. The initial analysis of the serial lateral cephalograms of these patients indicates that a spontaneous improvement in Class II molar relationship is a common occurrence. This spontaneous correction has forced us to rethink our approach to Class II molar correction treatment. Tradition ally, clinicians have viewed a Class II malocclusion as pri marily a sagittal and vertical problem. Experience with the post-RME correction of the Class II problem in growing patients indicates that many Class II malocclusions have a strong transverse component. The overexpansion of the maxilla, which subsequently is stabilized with a removable palatal plate, disrupts the occlusion. The patient apparently becomes more inclined to position the jaw slightly forward,19 thus eliminating the tendency toward a buccal crossbite and at the same time improving the sagittal occlusal relationship. Presumably, subsequent growth and remodeling of the structures of the temporomandibular joint make this initial postural change permanent. Spontaneous Class II correction, if it is going to occur, usually happens during the first 6 to 12 months of the postRME period. The Class II correction can be enhanced further at the end of the mixed-dentition period by way of a transpalatal arch that not only maintains the maxillary leeway space, but also can be activated sequentially to produce molar rotation and uprighting.2 At this point, if the occlusion still has a Class II component, additional treat ment approaches may be indicated (e.g., functional jaw orthopedics, Forsus appliance, Class II elastics). The phenomenon of spontaneous correction after RME treatment combined with routine use of a transpalatal arch is now part of our mixed-dentition treatment protocol. We have found that the need for subsequent functional jaw orthopedics has decreased substantially in our practice during the last decade.
CONCLUSION The various orthodontic problems discussed in this chapter are all linked to maxillary deficiency in the transverse or the sagittal dimension, or in both. Signs of maxillary deficiency include much more than anteroposterior crossbite and crowding of the maxillary dentition. Signs of maxillary defi ciency often appear together in maxillary deficiency syn drome. A proven orthopedic appliance, the rapid maxillary expander, can be incorporated easily into treatment plans directed toward a variety of orthodontic conditions. RME is useful in correcting both Class II and Class III problems as well as in resolving mild to moderate tooth-size/arch-perim eter discrepancies. In addition, RME can be used to “broaden the smile” while improving nasal airway function in some patients.20 Many or most of these signs appear in the same patient with maxillary deficiency, with rapid maxillary expansion available as an adjunct to fixed-appliance treat
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Fig. 12-9 Facial mask hooks have been added to the acrylic splint expander to allow for the attachment of elastics. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
Fig. 12-10 The orthopedic facial mask of Petit often is used in patients with Class III malocclusion. (From McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press.)
ment, a procedure that presumably will be incorporated into orthodontic treatment protocols with increasing frequency in the future.
ACKNOWLEDGMENT This chapter is written to honor Dr. Ram S. Nanda, Profes sor Emeritus and former Chair of the Department of Ortho dontics at the University of Oklahoma. The Nanda family has made important contributions to orthodontics, with his brothers Dr. Ravindra Nanda Chair of Orthodontics at the University of Connecticut and the late Dr. Surender K.
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Part II Clinical Management of Sagittal and Vertical Discrepancies
Nanda a fellow faculty member for many years at the Uni versity of Michigan. It is my pleasure to write this chapter in honor of Dr. Ram Nanda’s significant lifetime contributions to our specialty.
References 1. McNamara JA Jr: Maxillary transverse deficiency, Am J Orthod Dentofacial Orthop 117:567-570, 2000. 2. McNamara JA Jr, Brudon WL: Orthodontics and dentofacial orthopedics, Ann Arbor, Mich, 2001, Needham Press. 3. Howe RP, McNamara JA Jr, O’Connor KA: An examination of dental crowding and its relationship to tooth size and arch dimension, Am J Orthod 83:363-373, 1983. 4. Toth LR, McNamara JA Jr: Treatment effects produced by the twin block appliance and the FR-2 appliance of Fränkel com pared to an untreated Class II sample, Am J Orthod Dentofacial Orthop 116:597-609, 1999. 5. Burkhardt DR, McNamara JA Jr, Baccetti T: Maxillary molar distalization or mandibular enhancement: a cephalometric comparison of the Pendulum and Herbst appliances, Am J Orthod Dentofacial Orthop 123:108-116, 2003. 6. Freeman DC, McNamara JA Jr, Baccetti T, Franchi L: Longterm treatment effects of the FR-2 appliance of Fränkel, Am J Orthod Dentofacial Orthop (in press). 7. Freeman CS, McNamara JA Jr, Baccetti T, Franchi L: Treat ment effects of the Bionator and high-pull facebow combina tion followed by fixed appliances in patients with increased vertical dimension, Am J Orthod Dentofacial Orthop 131:184195, 2007. 8. Schulz SO, McNamara JA Jr, Baccetti T, Franchi L: Treatment effects of bonded RME and vertical pull chin cup followed by fixed appliances in patients with increased vertical dimension, Am J Orthod Dentofacial Orthop 128:326-336, 2005. 9. McNamara JA Jr: The role of the transverse dimension in orthodontic diagnosis and treatment, Monograph 36, Craniofacial
Growth Series, Ann Arbor, 1999, Center for Human Growth and Development, University of Michigan. 10. Vanarsdall RL Jr: Personal communication, 1992. 11. Guyer EC, Ellis E, McNamara JA Jr, Behrents RG: Components of Class III malocclusion in juveniles and adolescents, Angle Orthod 56:7-30, 1986. 12. DeClerck H: Unpublished data, 2007. 13. McNamara JA Jr: An orthopedic approach to the treatment of Class III malocclusion in young patients, J Clin Orthod 21:598608, 1987. 14. McGill JS, McNamara JA Jr: Treatment and post-treatment effects of rapid maxillary expansion and facial mask therapy. In McNamara JA Jr, editor. Growth modification: what works, what doesn’t and why, Monograph 36, Craniofacial Growth Series, Center for Human Growth and Development, Ann Arbor, 1999, University of Michigan. 15. Westwood PV, McNamara JA Jr, Baccetti T, et al: Long-term effects of early Class III treatment with rapid maxillary expan sion and facial mask therapy, Am J Orthod Dentofacial Orthop 123:306-320, 2003. 16. McNamara JA Jr: Components of Class II malocclusion in children 8-10 years of age, Angle Orthod 51:177-202, 1981. 17. Tollaro I, Baccetti T, Franchi L, Tanasescu CD: Role of posterior transverse interarch discrepancy in Class II, Division 1 maloc clusion during the mixed dentition phase, Am J Orthod Dentofacial Orthop 110:417-422, 1996. 18. Guest SS, McNamara JA Jr, Baccetti T, Franchi L: Improving Class II malocclusion as a “side-effect” of rapid maxillary expansion: a prospective clinical study, Submitted for publica tion, 2008. 19. Wendling LK, McNamara JA Jr, Franchi L, Baccetti T: Short-term skeletal and dental effects of the acrylic splint rapid maxillary expansion appliance, Angle Orthod 75:7-14, 2005. 20. Hartgerink DV, Vig PS, Abbott DW: The effect of rapid maxil lary expansion on nasal airway resistance, Am J Orthod Dentofacial Orthop 92:381-389, 1987.