CASE REPORT
Change in mandibular growth direction by means of a Herbst appliance? A case report Urban H~igg* Hong Kong The orthodontic treatment of a skeletal Class II, Division 1 malocclusion related to the general growth rate of the patient is described. The female patient was observed from the late juvenile period of growth to the termination of growth. The patient had a vertical facial growth pattern during the initial treatment and observation period (2.5 years). During treatment with the Herbst appliance and the activator, the mandible grew forward. During treatment with the fixed appliance and the period of retention, the vertical growth pattern of the mandible returned. (AM J ORTHODDENTOFAC ORTHOP 1992;102:456-63.) C l a s s II, Division 1 malocclusion is common, and many of those patients have a retrognathic mandible. Major factors affecting the outcome of orthodontic treatment of Angle Class II, Division 1 malocclusion in growing patients are the amount of growth, growth rate, and growth direction of the maxilla and mandible. It would seem to make sense in the treatment of those patients to inhibit forward growth of the maxilla and enhance forward growth of the mandible in combination with tooth mo~'ements. It has been shown that the skeletal contribution to the change from Class II to Class I dental arch relationship is greater when the patient is treated in a period when the general growth rate is high, i.e., close to the pubertal maximum o f standing height in comparison with patients treated before or after that period of time. ~'2 After unfavorable growth has been affected successfully by orthodontic measures, growth returns to its original direction. 3 Accordingly, when treating a patient with an Angle Class II, Division 1 malocclusion who has an unfavorable growth pattern, the use of an efficient appliance that has the capability of changing growth direction is recommended. Performing active orthodontic treatment at a time when the growth rate and amount is large, followed by a period with little or no growth, is desirable.
CASE REPORT History, clinical finding, and diagnosis In 1980 a girl, 9 years and 8 months old, was seen at the orthodontic department in MalmS, Sweden. Her chief complaints were her protruding teeth, and difficulties in closing her lips, and teasing by her peers because of her appearance. The patient was deaf in her right ear. She slept with her *Department of Orthodontics, Faculty of Odontology, MalmS, Sweden, and Departmentof Children's Dentistryand Orthodontics,The Prince Philip Dental Hospital, Universityof Hong Kong, Hong Kong. 814126467
456
mouth open but had open nasal passages. The remarkable features of her facial appearance included a convex, retrognatic profile, lip incompetence, protrusion of the upper lip, and marked activity of the mentalis muscle during swallowing. Her father had a similar facial appearance. There was a history of thumb sucking until the age 8V2 years. Poor oral hygiene and gingivitis were notable. The initial malocclusion was Class II, Division 1 with an overjet of 14 mm and overbite of 0 mm (Fig. 1). The maxillary dental arch was narrow, with a slightly rotated right lateral incisor. In the mandibular dental arch, the first deciduous molars had been extracted, and excessive tooth migration had occurred, predominantly on the left side. There was 6 mm crowding, and the curve of Spee was pronounced. The orthopantomogram showed no abnormalities and no sign of the development of the third molars. Cephalometric analysis (Fig. 2 and Table I) indicated a convex, retrognathic skeletal profile, with bimaxillary retrognathism. The mandibular plane angle was increased, suggesting a vertical facial growth pattern, and the maxillary incisors were proclined.
Treatment plan The specific objectives were (1) to treat the sagittal skeletal discrepancy between the maxilla and the mandible by inhibiting the forward growth of the maxilla and to stimulate mandibular condylar growth and guide it into a more favorable direction; (2) to avoid any opening rotation of the mandible; (3) to create space and alignment of the dental arches; and (4) to reduce the overjet by changing the inclination of the maxillary incisors and by affecting the skeletal growth pattern as described previously. To achieve these objectives, a treatment plan that included five components (Table 1I, periods I through V) was developed. Period I. (1) Reduction of the overjet and improvement of the facial esthetics. This would hopefully stop her peers teasing her, and moreover, reduce the risk of traumatic injuries to the maxillary incisors. (2) The creation of space for the eruption of two of the anchor teeth for the Herbst appliance, the first mandibular premolars.
Volume 102
Case report
Number 5
J 4
-dr
"
,t
Fig. 1. Pretreatment study models. Period II. Treatment of the facial skeletal problem during an intense period of growth with an efficient orthodontic appliance. Period III. The guidance of the growth of the maxilla and the mandible into the most favorable pattern until the growth rate diminished. Period IV. Alignment and placement of the teeth in the proper positions. Period V. The use of retention until facial growth had almost ceased.
Treatment progress During the initial treatment, the overjet was reduced from 14 to 8 mm because of the change in inclination of the maxillary and mandibular incisors (Table I; Figs. 1, 3, and 8A, I). The initial treatment was done with a removable expansion plate, which had a labial bow with u-loops, in the upper jaw and a fixed appliance in the lower jaw. After active treatment, the removable appliance was deactivated and used as a retainer. In the lower jaw, a lingual arch soldered to bands on the first molars was inserted as a retainer. The growth of the mandible was purely vertical and did not contribute to the reduction of the overjet. The growth rate of standing height
Fig. 2. Pretreatment cephalometrics.
457
458
Hiigg
Am. J. Orthod. Dentofac. Orthop.
November 1992
Fig. 3. Study models after initial treatment (period I).
MM/' f'EAR I
100-
II IIIIV
V
VI
8o604o~ 2o~ '$'
'1'2 . . . . . YEARS
Fig. 4. Growth velocity curve from 9.8 to 18 years ofage."The Roman figures refer to the different periods of orthodontic measures. (For explanation, see Table I.)
(Fig. 4) was appreciable during the first year of active orthodontic treatment (6.9 cm), but dropped during the following year of retention (4.3 cm). Then there was a marked increase in growth rate of standing height, indicating that the pubertal growth spurts of standing height and facial growth were being achieved.4"5 In 8 months (period II) of treatment with the Herbst appliance, the dental arch relationship changed from Class II to Class I, and the overjet was overcorrected (Fig. 3, 5, and 8A, II). The sagittal relationship between the maxilla and the mandible improvcd because the mandible came forward, and the position of the maxilla was unchanged. Before treatment with the Herbst appliance, the direction of mandibular growth was purely vertical (Fig. 8A, I); during the Herbst treatment, it became sagittal (Fig. 8, II). There was a marked proclination of the mandibular incisors during the Herbst treatment (Table I; Fig. 8A, I1). The Herbst appliance used was designed with total achorage, according to Panch-
Volume 102 Number 5
Case report
459
Fig. 5. Study models after Herbst treatment (period II). Table I. Cephalometric analysis at several registrations during the orthodontic treatment and follow-up of a
girl with Class II, Division 1 malocclusion (For definitions of the periods, see Table I) Period
' Measure/age (yr) Height (cm) SNA SNB AMB ILs/NL ILi/ML NSL/ML Ii-AP N-Sp'/Sp-Gn UI-E LI-E
9.8 134.4 78 67 11 120 98 46 0 80% 2.5 0.5
I
" 12.1 148.0 77 ( - I) 67 10 ( - 1) 104 106 47 ( + I) 3 . . .
I
"
I
12.8 155.3 77 70 ( + 3) 7 (-3) 104.5 122 46 ( - 1) 7 . . .
. . .
'~ 14.0 164.0 76 ( - 1) 70 6 ( - 1) 109 19.5 45 ( - 1) 6.5 . . .
I
~
I
14.8 167.3 75 ( - 1) 70 5 ( - 1) 108 93 45 1.5 . . .
~' 16.6 170.2 75 70 5 108 92.5 45 1
. .
I 18.0 171.0 75 70 5 108 92.5 45 1 77% 6 4
460
Hiigg
Am. J. Orthod. Oentofac. Orthop. November 1992
Fig. 6. Study models after activator treatment (period III).
T a b l e II. Definition o f periods o f the orthodontic treatment and f o l l o w - u p o f a girl with Class II, Division 1 malocclusion
Age O'r)
Aim
I II
9.6 12.0
Ill IV
12.8 14.0
V VI
14.8 16.6 18.0
Reduce overjet, create space Change from Class II to Class I dental arch relationship Guidance of growth Create space and alignment of the dental arches Retention Retention period completed Follow-up 17 months out of retention
Periods
[
erz. 6 The skeletal effect achieved with the Herbst appl'iance was maintained and further improved during the activator treatment (Table I; Fig. 8A, III). During the activator treatment, the Class I dental arch relationship was maintained,
[
Measure Removable plate fixed appliance, retention Herbst appliance Activator for open bite case Begg appliance, extraction first premolars Retainers
and there was crowding in the mandibular incisor region (Fig. 6). Space was achieved by extracting the first premolars, and the teeth were moved into proper positions with a fixed Begg appliance over 8 months (period IV). Only Class I elastics
Volume 102 Number 5
Case report
461
w
Fig. 7. Posttreatment study models (after first premolar extraction, fixed appliance, retention, and follow-up, periods IV through VI). were used to avoid opening the mandibular plane angle. During period IV, the vertical growth pattern of the mandible returned (Fig. 8A, IV). However, the sagittal skeletal relationship was slightly improved as a result of the rcduction of the SNA angle. After treatment with fixed appliances, a proper inclination of the incisors was achieved (Table I; Fig. 8A~ IV). During the retention period (Fig. 8A, V), there was further vertical growth of the mandible and a slight uprighting of the position of the mandibular incisors. There were no dental or skeletal changes during the follow-up period (Table I; Figs. 7, 8 A, VI). The growth pattern of the mandible is also shown in Fig. 8B.
Treatment results The facial appearance changed significantly during the 8year period that the patient was followed. The lips became' competent and their position in relation to the esthetic line was also improved (Table I; Figs. 9 and 10). The change of lip position is probably due to the rctroclination of the max-
illary incisors and the forward positioning of the mandible during the observation period (Fig. 9). She was followed from the late prepubertal period until her general and facial growth had terminated (Fig. 4). The study model analysis showed that the Class II dental arch relationship had changed to a Class I dental arch relationship, and the overjet was reduced from 14 to 3 mm. The overbite was increased from 0 to 3 mm, and the midline was correctcd. The dental arches were aligned and no crowding had appeared during the follow-up period. The extraction sites were closed despite a very slight opening of the left maxillary extraction site at 18 years (Fig. 7). Accordingly, the shape of dental arches and the relationship between the dental arches became quite close to the ideal norm. Ccphalomctrics (Table I, Fig. 8B) showed that during the initial treatment (period 1) the mandible grew vertically. During period II and I11, forward growth of the maxilla was inhibited, and the mandible grew forward, in almost equal increments, contributing to the reduction of the ANB angle
462
Hiigg
Am. J. Orthod. Oentofac. Orthop. November 1992
1
II
III
IV
V, VI
Fig. 8A. Cephalometric superimpositions. L Dental and skeletal changes during the initial treatment, 9.6 to 12 years. It. Dental and skeletal changes during the Herbst treatment, 12 to 12.8 years. 111. Dental and skeletal changes during the activator treatment, 12.8 to 14.0 years. IV. Dental and skeletal changes during treatment with the fixed appliance and extraction of first premolars 14 to 14.8 years. V. Dental and skeletal changes during the retention period, 14.8 to 16.6 years. Vl. During the followup period, 16.6 to 18 years, no dental and skeletal changes occurred.
a = , ==
/i
, y/ /a / ~
~ "=-
..--''.'f-~
,i I I
..1=,,-"
\ LII,I",",.
ti
-,"/
II \ Fig. 8B. Cephalometric superimposition on sella and NSL line showing position of mandible at six observations mentioned in Fig. 8A.
%% E-line
Fig. 9. Cephalometric superimpositions at 9.6 nd 18 years.
Volume 102 IVumber 5
Case report
463
Fig. 10. Patient profile at the ages of 9.8 and 18 years.
from 11 ~ to 6 ~ The forward growth of the maxilla was further inhibited during treatment with the fixed appliance (period IV). The interincisal angle was increased from 107 ~ to 137 ~ The mandibular plane angle remained unchanged. The change in growth direction of the mandible occurred when the patient was treated with functional appliances. It has been reported that growth direction in the condyle may change during the pubertal growth spurt in some persons. 7 This patient was treated with the Herbst appliance for 10 months and then was treated for 14 months with an activator. The amount of mandibular growth, especially during the Herbst treatment, indicates that treatment took place when the mandibular growth rate was high. The mandibular growth rate of the patient was estimated by an indirect tool, by analyzing her velocity curve of standing height, a method devised for orthodontic purposes by Bjrrk. 4 The treatment with the functional appliances took place close to and just after the pubertal maximum of standing height (Fig. 4) when the mandibular growth is at or close to its pubertal maximum. ~5 It seems possible to stimulate condylar growth with the Herbst appliance, 8 but the inhcrent mandibular growth rate during treatment is of major importance for the total ourcome. 9 The direction of mandibular growth after treatment with the Herbst appliance and the activator returned to its original vertical vector. As the growth rate was low, it did not have any influence on the occlusion or the sagittal relationship between the maxilla and mandible. Though even in a patient with a severe skeletal Class II and an unfavorable mandibular growth pattern, it seems to be possible to change the direction of mandibular growth and get a marked skeletal contributi0fi to the change from Class II to Class I dental arch relationship by means of functional appliances, and to maintain the effect until growth ceases.
REFERENECS I. Pancherz H, Hagg U. Dentofacial orthopedics in relationship to somatic maturation. AM J ORTttOD 1985;88:273-87. 2. Malmgren O, Omblus J, H~igg U, Pancherz H. Treatment with orthopedic appliance system in relation to treatment intensity and growth periods. AM J ORTHOD DEN'I'OFACOR'rItOP 1987;91:!4351. 3. Nielsen B, Enemark H. Effect of cervical anchorage studied by the implant method. Trans Eur Orthod Soc 1969;45:435-47. 4. Bjrrk A. Timing of interceptive orthodontic measures based on stages of maturation. Trans Europ Orthod Soc 1972;48:61-74. 5. Baughan B, Demirjian A, Levesque G-Y, LaPalme-Chaput L. The pattern of facial growth before and during puberty as shown by French-Canadian girls. Ann Hum Biol 1979;6:59-76. 6. Pancherz H. The Herbst appliance--its biological effects and clinical use. AM J ORTHOD 1985;87:1-20. 7. Bjrrk A. Variations in the growth pattern of human mandible. Longitudinal radiographic study by the implant method. J Dent Res 1963;42:319-36. 8. Pancherz tt. Treatment of Class 11 malocclusion by jumping the bite with the Herbst appliance: a cephalometric investigation. A.',I J OR'roOD 1979;76:423-41. 9. tt~iggU, Pancherz H, Taranger J. Pubertal growth and orthodontic treatment. In: Carlson D, Ribbens K, cds. Craniofacial growth during adolescence. Monograph 20, Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development, The University of Michigan, pp. 87-115. Reprhtt requests to:
Dr. Urban H/igg Dept. of Children's Dentistry nd Orthodontics The Prince Philip Dental Hospital University of tlong Kong 34, Hospital Rd. Hong Kong
Change in mandibular growth direction by means of a Herbst appliance? A case report Urban H~igg* Hong Kong The orthodontic treatment of a skeletal Class II, Division 1 malocclusion related to the general growth rate of the patient is described. The female patient was observed from the late juvenile period of growth to the termination of growth. The patient had a vertical facial growth pattern during the initial treatment and observation period (2.5 years). During treatment with the Herbst appliance and the activator, the mandible grew forward. During treatment with the fixed appliance and the period of retention, the vertical growth pattern of the mandible returned. (AM J ORTHODDENTOFAC ORTHOP 1992;102:456-63.) C l a s s II, Division 1 malocclusion is common, and many of those patients have a retrognathic mandible. Major factors affecting the outcome of orthodontic treatment of Angle Class II, Division 1 malocclusion in growing patients are the amount of growth, growth rate, and growth direction of the maxilla and mandible. It would seem to make sense in the treatment of those patients to inhibit forward growth of the maxilla and enhance forward growth of the mandible in combination with tooth mo~'ements. It has been shown that the skeletal contribution to the change from Class II to Class I dental arch relationship is greater when the patient is treated in a period when the general growth rate is high, i.e., close to the pubertal maximum o f standing height in comparison with patients treated before or after that period of time. ~'2 After unfavorable growth has been affected successfully by orthodontic measures, growth returns to its original direction. 3 Accordingly, when treating a patient with an Angle Class II, Division 1 malocclusion who has an unfavorable growth pattern, the use of an efficient appliance that has the capability of changing growth direction is recommended. Performing active orthodontic treatment at a time when the growth rate and amount is large, followed by a period with little or no growth, is desirable.
CASE REPORT History, clinical finding, and diagnosis In 1980 a girl, 9 years and 8 months old, was seen at the orthodontic department in MalmS, Sweden. Her chief complaints were her protruding teeth, and difficulties in closing her lips, and teasing by her peers because of her appearance. The patient was deaf in her right ear. She slept with her *Department of Orthodontics, Faculty of Odontology, MalmS, Sweden, and Departmentof Children's Dentistryand Orthodontics,The Prince Philip Dental Hospital, Universityof Hong Kong, Hong Kong. 814126467
456
mouth open but had open nasal passages. The remarkable features of her facial appearance included a convex, retrognatic profile, lip incompetence, protrusion of the upper lip, and marked activity of the mentalis muscle during swallowing. Her father had a similar facial appearance. There was a history of thumb sucking until the age 8V2 years. Poor oral hygiene and gingivitis were notable. The initial malocclusion was Class II, Division 1 with an overjet of 14 mm and overbite of 0 mm (Fig. 1). The maxillary dental arch was narrow, with a slightly rotated right lateral incisor. In the mandibular dental arch, the first deciduous molars had been extracted, and excessive tooth migration had occurred, predominantly on the left side. There was 6 mm crowding, and the curve of Spee was pronounced. The orthopantomogram showed no abnormalities and no sign of the development of the third molars. Cephalometric analysis (Fig. 2 and Table I) indicated a convex, retrognathic skeletal profile, with bimaxillary retrognathism. The mandibular plane angle was increased, suggesting a vertical facial growth pattern, and the maxillary incisors were proclined.
Treatment plan The specific objectives were (1) to treat the sagittal skeletal discrepancy between the maxilla and the mandible by inhibiting the forward growth of the maxilla and to stimulate mandibular condylar growth and guide it into a more favorable direction; (2) to avoid any opening rotation of the mandible; (3) to create space and alignment of the dental arches; and (4) to reduce the overjet by changing the inclination of the maxillary incisors and by affecting the skeletal growth pattern as described previously. To achieve these objectives, a treatment plan that included five components (Table 1I, periods I through V) was developed. Period I. (1) Reduction of the overjet and improvement of the facial esthetics. This would hopefully stop her peers teasing her, and moreover, reduce the risk of traumatic injuries to the maxillary incisors. (2) The creation of space for the eruption of two of the anchor teeth for the Herbst appliance, the first mandibular premolars.
Volume 102
Case report
Number 5
J 4
-dr
"
,t
Fig. 1. Pretreatment study models. Period II. Treatment of the facial skeletal problem during an intense period of growth with an efficient orthodontic appliance. Period III. The guidance of the growth of the maxilla and the mandible into the most favorable pattern until the growth rate diminished. Period IV. Alignment and placement of the teeth in the proper positions. Period V. The use of retention until facial growth had almost ceased.
Treatment progress During the initial treatment, the overjet was reduced from 14 to 8 mm because of the change in inclination of the maxillary and mandibular incisors (Table I; Figs. 1, 3, and 8A, I). The initial treatment was done with a removable expansion plate, which had a labial bow with u-loops, in the upper jaw and a fixed appliance in the lower jaw. After active treatment, the removable appliance was deactivated and used as a retainer. In the lower jaw, a lingual arch soldered to bands on the first molars was inserted as a retainer. The growth of the mandible was purely vertical and did not contribute to the reduction of the overjet. The growth rate of standing height
Fig. 2. Pretreatment cephalometrics.
457
458
Hiigg
Am. J. Orthod. Dentofac. Orthop.
November 1992
Fig. 3. Study models after initial treatment (period I).
MM/' f'EAR I
100-
II IIIIV
V
VI
8o604o~ 2o~ '$'
'1'2 . . . . . YEARS
Fig. 4. Growth velocity curve from 9.8 to 18 years ofage."The Roman figures refer to the different periods of orthodontic measures. (For explanation, see Table I.)
(Fig. 4) was appreciable during the first year of active orthodontic treatment (6.9 cm), but dropped during the following year of retention (4.3 cm). Then there was a marked increase in growth rate of standing height, indicating that the pubertal growth spurts of standing height and facial growth were being achieved.4"5 In 8 months (period II) of treatment with the Herbst appliance, the dental arch relationship changed from Class II to Class I, and the overjet was overcorrected (Fig. 3, 5, and 8A, II). The sagittal relationship between the maxilla and the mandible improvcd because the mandible came forward, and the position of the maxilla was unchanged. Before treatment with the Herbst appliance, the direction of mandibular growth was purely vertical (Fig. 8A, I); during the Herbst treatment, it became sagittal (Fig. 8, II). There was a marked proclination of the mandibular incisors during the Herbst treatment (Table I; Fig. 8A, I1). The Herbst appliance used was designed with total achorage, according to Panch-
Volume 102 Number 5
Case report
459
Fig. 5. Study models after Herbst treatment (period II). Table I. Cephalometric analysis at several registrations during the orthodontic treatment and follow-up of a
girl with Class II, Division 1 malocclusion (For definitions of the periods, see Table I) Period
' Measure/age (yr) Height (cm) SNA SNB AMB ILs/NL ILi/ML NSL/ML Ii-AP N-Sp'/Sp-Gn UI-E LI-E
9.8 134.4 78 67 11 120 98 46 0 80% 2.5 0.5
I
" 12.1 148.0 77 ( - I) 67 10 ( - 1) 104 106 47 ( + I) 3 . . .
I
"
I
12.8 155.3 77 70 ( + 3) 7 (-3) 104.5 122 46 ( - 1) 7 . . .
. . .
'~ 14.0 164.0 76 ( - 1) 70 6 ( - 1) 109 19.5 45 ( - 1) 6.5 . . .
I
~
I
14.8 167.3 75 ( - 1) 70 5 ( - 1) 108 93 45 1.5 . . .
~' 16.6 170.2 75 70 5 108 92.5 45 1
. .
I 18.0 171.0 75 70 5 108 92.5 45 1 77% 6 4
460
Hiigg
Am. J. Orthod. Oentofac. Orthop. November 1992
Fig. 6. Study models after activator treatment (period III).
T a b l e II. Definition o f periods o f the orthodontic treatment and f o l l o w - u p o f a girl with Class II, Division 1 malocclusion
Age O'r)
Aim
I II
9.6 12.0
Ill IV
12.8 14.0
V VI
14.8 16.6 18.0
Reduce overjet, create space Change from Class II to Class I dental arch relationship Guidance of growth Create space and alignment of the dental arches Retention Retention period completed Follow-up 17 months out of retention
Periods
[
erz. 6 The skeletal effect achieved with the Herbst appl'iance was maintained and further improved during the activator treatment (Table I; Fig. 8A, III). During the activator treatment, the Class I dental arch relationship was maintained,
[
Measure Removable plate fixed appliance, retention Herbst appliance Activator for open bite case Begg appliance, extraction first premolars Retainers
and there was crowding in the mandibular incisor region (Fig. 6). Space was achieved by extracting the first premolars, and the teeth were moved into proper positions with a fixed Begg appliance over 8 months (period IV). Only Class I elastics
Volume 102 Number 5
Case report
461
w
Fig. 7. Posttreatment study models (after first premolar extraction, fixed appliance, retention, and follow-up, periods IV through VI). were used to avoid opening the mandibular plane angle. During period IV, the vertical growth pattern of the mandible returned (Fig. 8A, IV). However, the sagittal skeletal relationship was slightly improved as a result of the rcduction of the SNA angle. After treatment with fixed appliances, a proper inclination of the incisors was achieved (Table I; Fig. 8A~ IV). During the retention period (Fig. 8A, V), there was further vertical growth of the mandible and a slight uprighting of the position of the mandibular incisors. There were no dental or skeletal changes during the follow-up period (Table I; Figs. 7, 8 A, VI). The growth pattern of the mandible is also shown in Fig. 8B.
Treatment results The facial appearance changed significantly during the 8year period that the patient was followed. The lips became' competent and their position in relation to the esthetic line was also improved (Table I; Figs. 9 and 10). The change of lip position is probably due to the rctroclination of the max-
illary incisors and the forward positioning of the mandible during the observation period (Fig. 9). She was followed from the late prepubertal period until her general and facial growth had terminated (Fig. 4). The study model analysis showed that the Class II dental arch relationship had changed to a Class I dental arch relationship, and the overjet was reduced from 14 to 3 mm. The overbite was increased from 0 to 3 mm, and the midline was correctcd. The dental arches were aligned and no crowding had appeared during the follow-up period. The extraction sites were closed despite a very slight opening of the left maxillary extraction site at 18 years (Fig. 7). Accordingly, the shape of dental arches and the relationship between the dental arches became quite close to the ideal norm. Ccphalomctrics (Table I, Fig. 8B) showed that during the initial treatment (period 1) the mandible grew vertically. During period II and I11, forward growth of the maxilla was inhibited, and the mandible grew forward, in almost equal increments, contributing to the reduction of the ANB angle
462
Hiigg
Am. J. Orthod. Oentofac. Orthop. November 1992
1
II
III
IV
V, VI
Fig. 8A. Cephalometric superimpositions. L Dental and skeletal changes during the initial treatment, 9.6 to 12 years. It. Dental and skeletal changes during the Herbst treatment, 12 to 12.8 years. 111. Dental and skeletal changes during the activator treatment, 12.8 to 14.0 years. IV. Dental and skeletal changes during treatment with the fixed appliance and extraction of first premolars 14 to 14.8 years. V. Dental and skeletal changes during the retention period, 14.8 to 16.6 years. Vl. During the followup period, 16.6 to 18 years, no dental and skeletal changes occurred.
a = , ==
/i
, y/ /a / ~
~ "=-
..--''.'f-~
,i I I
..1=,,-"
\ LII,I",",.
ti
-,"/
II \ Fig. 8B. Cephalometric superimposition on sella and NSL line showing position of mandible at six observations mentioned in Fig. 8A.
%% E-line
Fig. 9. Cephalometric superimpositions at 9.6 nd 18 years.
Volume 102 IVumber 5
Case report
463
Fig. 10. Patient profile at the ages of 9.8 and 18 years.
from 11 ~ to 6 ~ The forward growth of the maxilla was further inhibited during treatment with the fixed appliance (period IV). The interincisal angle was increased from 107 ~ to 137 ~ The mandibular plane angle remained unchanged. The change in growth direction of the mandible occurred when the patient was treated with functional appliances. It has been reported that growth direction in the condyle may change during the pubertal growth spurt in some persons. 7 This patient was treated with the Herbst appliance for 10 months and then was treated for 14 months with an activator. The amount of mandibular growth, especially during the Herbst treatment, indicates that treatment took place when the mandibular growth rate was high. The mandibular growth rate of the patient was estimated by an indirect tool, by analyzing her velocity curve of standing height, a method devised for orthodontic purposes by Bjrrk. 4 The treatment with the functional appliances took place close to and just after the pubertal maximum of standing height (Fig. 4) when the mandibular growth is at or close to its pubertal maximum. ~5 It seems possible to stimulate condylar growth with the Herbst appliance, 8 but the inhcrent mandibular growth rate during treatment is of major importance for the total ourcome. 9 The direction of mandibular growth after treatment with the Herbst appliance and the activator returned to its original vertical vector. As the growth rate was low, it did not have any influence on the occlusion or the sagittal relationship between the maxilla and mandible. Though even in a patient with a severe skeletal Class II and an unfavorable mandibular growth pattern, it seems to be possible to change the direction of mandibular growth and get a marked skeletal contributi0fi to the change from Class II to Class I dental arch relationship by means of functional appliances, and to maintain the effect until growth ceases.
REFERENECS I. Pancherz H, Hagg U. Dentofacial orthopedics in relationship to somatic maturation. AM J ORTttOD 1985;88:273-87. 2. Malmgren O, Omblus J, H~igg U, Pancherz H. Treatment with orthopedic appliance system in relation to treatment intensity and growth periods. AM J ORTHOD DEN'I'OFACOR'rItOP 1987;91:!4351. 3. Nielsen B, Enemark H. Effect of cervical anchorage studied by the implant method. Trans Eur Orthod Soc 1969;45:435-47. 4. Bjrrk A. Timing of interceptive orthodontic measures based on stages of maturation. Trans Europ Orthod Soc 1972;48:61-74. 5. Baughan B, Demirjian A, Levesque G-Y, LaPalme-Chaput L. The pattern of facial growth before and during puberty as shown by French-Canadian girls. Ann Hum Biol 1979;6:59-76. 6. Pancherz H. The Herbst appliance--its biological effects and clinical use. AM J ORTHOD 1985;87:1-20. 7. Bjrrk A. Variations in the growth pattern of human mandible. Longitudinal radiographic study by the implant method. J Dent Res 1963;42:319-36. 8. Pancherz tt. Treatment of Class 11 malocclusion by jumping the bite with the Herbst appliance: a cephalometric investigation. A.',I J OR'roOD 1979;76:423-41. 9. tt~iggU, Pancherz H, Taranger J. Pubertal growth and orthodontic treatment. In: Carlson D, Ribbens K, cds. Craniofacial growth during adolescence. Monograph 20, Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development, The University of Michigan, pp. 87-115. Reprhtt requests to:
Dr. Urban H/igg Dept. of Children's Dentistry nd Orthodontics The Prince Philip Dental Hospital University of tlong Kong 34, Hospital Rd. Hong Kong
