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An American Board of Orthodontics case report Correction of class I crowding in an achondroplastic patient
n Bead of Orthodontics ease rep0
n
o~~~tio~ of Class I crowding in an achondyoplastic patient d. Patrick Dunbar, DDS, Bruce Goldin, PhD, DMD, and d. Daniel Subtelny, DDS, Rochester, N.Y.
n the treatment of any malocclusion, the orthodontist needs to consider many factors including the growth potential of the patient. In cases in which growth may be intenupted or deficient because of genetic factors, special attention must be given. Treatment modalities may be limited since “normal” growth cannot be used as a positive treatment factor.
Diagnosis The patient had a Class I malocclusion with severe maxillary retrnsion and decreased maxillary vertical height. The anterior palate was tipped up. There was maxillary anterior crowding with both lateral incisors in crossbite. The left buccal segment was also in crossbite. The lower arch exhibited moderate anterior crowding. This patient had large adenoids but was a nasal breather. Her previous mandibular positioning was direct horizontally as a result of overclosure (Fig. 1). From the Eastman Dental Center. Presented to the American Board of Orthodontics in partial fulfdlment of the requirements for the certification process conducted by the Board. 8/4/11458
History
The patient, a girl 11 years 4 months of age, was first seen with achondroplasia. A tonsillectomy and myringotomy with tube insertion were performed at age 5 years. The patient was an otherwise well-adjusted, healthy, and intelligent person. Facial appearance Typical of achondroplasia, the patient exhibited a concave soft-tissue profile with a bulging forehead and a retrognathic maxilla. The nose was saddle-shaped in appearance because of lack of development of the nasomaxillary complex. There were no apparent major asymmetries judging from both the lateral and frontal photographs (Fig. 2). Etiology
The malocclusion and the facial appearance illustrate genetic characteristics. Achondroplasia is an autosomaldominant trait that equally affects males and females. Its clinical manifestation that is of concern to orthodontists is the effect on the cranial base (chondrocranium), which is cbaracteristically small yet the cranial vault continues to grow, compensafing for the developing brain. Disproportionate growth results.
Fig. 1. Intraoral slides, December 1980.
A m . .I Orthod. Dtwlofic. Orthop. Septemkr I989
Dunbar, Goldin, and Subtelny
Fig. 1 (Cont’d). Study models, December 1980
Gephalometric findings
Skeletally the chin was slightly forward with a facial angle of 87” when compared with the Michigan mean of 84.6” at age 11. The maxilla was positioned posteriorly to nasion with a 79” FH-NA angle (mean 88”). The profile was concave with a - 12” angle of convexity. Radiographic evaluation of the adenoids showed approximately 75% airway obstruction. The
frontal radiograph showed slight maxillary constriction. Nasal width was within normal limits, bnt cloudiness in the airway was apparent. The denture bases basically mirrored their skeleta; bases with an SNB of 81” (mean 77.3”), an SNA of 74” (mean 81. l”), and an ANB of 7” (mean 3.8”). These findings, along with an A-B/NPg of 6” (mean -5.9”): indicated a poor
Fig. 2. Facial photographs, December 1980.
C Fig. 3. Cephalometric tracings. A, Initial tracing, December 1980. B, Retention tracing, November
1984. C, Postretention tracing, April 1987.
Am. .;. mkd. Drntofac. Ortlwp.
Dunbar, Goldin, and Subtelny
September
1989
Fig. 4. Facial photographs, November 1984.
able I. Gephalometric
findings
Initial Measurement , Facial angle (“) NA-FH (“) Angel of convexity (“) MP angle (“) SNA (“) SNB (“) Y axis (“) N-ANS (mm) N-ME (mm) UFH/TFH(%) Interincisal angle (“) Upper 1 -paIatal plane (“) Upper I-FH (“) Lower I-MP (“) Lower I-AP angular (“) Upper LAP iinear (mm) Lower I-AP linear (nun)
I2180
Mean Michigan-l I yr
Retention 11184
Postretention 4187
Mean Michigan-16 yr
87.0 79.0 -12.0
84.6 88.0 6.6
86.0 88.0 -15.5
88.0 79.0 -15.0
26.0 74.0 81.0 59.0 38.0 106.0 35.8 127.0
28.8 77.3 60.6 52.7 116.2 45.3 126.9
27.5 73.0 81.0 61.5 41.0 34.7 122.0
26.0 75.0 82.0 60.0 41.0 119.0 34.4 122.0
79.2 59.6 55.1 123.2 45.2 133.6
114.0
112.8
113.5
111.0
Ill.!
122.0 -4.5 16.0
112.5 3.3 22.5
123.0 -2.0 29.0
122.0 0.0 31.0
111.1
8.0
6.5
13.0
10.5
5.2
5.5
1.6
8.0
8.0
0.8
81.1
denture base relationship to each other and an abnormal skeleta1 profile. The vertical dimension showed decreased upper facial to totai facial height attributable in part to the palatal plane being
118.1
86.0 87.9 3.2 25.8
$1.8
5.2 21.8
tipped up anteriorly. The mandibular plane was slightly 9at relative to the mean, 26” versus a mean of 28.8“. Dentally the maxillary incisors were prochned relative to the SN plane and Frankfort horizontal plane, ? 16.5” and 122”,
Volume 96 Number 3
Fig. 5. Study models at retention, November 1984.
respectively, with means of 105.1” and 112.5”. Relative to the palatal plane, the upper incisor was well related due to the upward anterior palatal tilt. The mandibular incisors were slightly retroclined relative to the mandibular plane at 85.5” (mean 93.3”). The incisal edges of both maxillary and mandibular incisors were positioned anteriorly relative to the A-PO plane at 8 mm and 5.5 mm, respectively, with means of 6.5 mm and 1.6 mm (Fig. 3 and Table I).
Plan of treatment The initial plan was to proceed with nonextraction therapy. A fixed Hyrax rapid palatal developer was to be used to expand the maxilla, correct the left posterior crossbite, and gain arch length. Occlusal acrylic overlays were to be integrated with the Hyrax and placed over the maxillary first and second molars to help prevent buccal flaring of these teeth during expansion. Nasomaxillary advancement was to be accomplished with fixed appliances incorporating anterior labial
A m . 2. Orthod. Demfac.Orthop. September 1989
Dunbar, Goldin, and Subtelny
root torque and fabce mask therapy. A lip bumper was to be used in the lower arch to upright the first and second molars, gain arch length, and slightly open the mandibular plane to decrease the skeletal concavity. The possible need for a lower arch extraction was left for reevaluation, depending on t h e outcome of ongoing treatment. progress 06 treatment
A Hyrax rapid palatal expansion appliance with occlusal acrylic coverage was cemented to the first premolars and first molars. Activation was discontinued 14 days later and the
achieved changes were stabilized after 2.5 mm of expansion with correction of the buccal crossbite. At that time the maxillary incisor brackets were bonded and arch wires fabricated with anterior labial root torque to advance me maxillary incisors. After 6 months of treatment, a maxillary holding appliance was placed. The patient stated that nasal breaking was much easier. A lip bumper was placed to the lower first molars. Biteblocks off the maxillary holding appliance were used to decrease the possibility of bite opening as the lower molars uprighted. Face mask therapy was added 8 months into treatment to stimulate anterior positioning of the nasomaxillary complex. The face mask was discontinued after 2 months when sufficient space for the maxillary lateral incisors was gained. The maxillary canines were then brought into the arch. A palatal holding appliance with rotation loops was fixed to the maxillary second molars 15 months into treatment to hold eruption and gain better mesial-buccal molar rotation. After 24 months of treatment, it was decided to extract a lower lateral incisor because of deficient anterior arch length. The spaces were closed by use of power chain modules. Forty-two months after initiation of active treatment, appliances were removed. A maxillary edgewise Hawley retainer and a lower lingual bonded 3-3 fixed retamer were placed. Results achieved
~ 6. Superimposition tracing, December 1980, November 4984.
Facial. The lateral views show a profile that is still concave in appearance. However, the concavity s e e m s t o have remained stable without worsening (Fig. 4).
Fig. 7. Facial photographs, April 1987.
Volume 96 Number 3
Dental. A super Class I molar relationship with a Class III tendency at the canines has resulted. This is primarily attributable to a deficient maxilla. All teeth are in the arch and in good alignment (Fig. 5). Cephalometric analysis at retention. At age 15, the chin to forehead relationship has remained relatively stable and now is slightly posterior to the Downs mean, 86” versus a mean of 87.2”. The anteroposterior position of the maxilla has decreased 2” to 77” for the FH-NA angle; the angle of facial convexity has become slightly more concave. The man-
dibular plane has remained reasonably stable with an increase of 1.5”. The vertical dimension has remained relatively constant, although the maxilla appears to have moved slightly inferiorly relative to the anterior tubercle of the atlas. The upper facial height to total facial height ratio is virtually unchanged. Dentally the proclination of the maxillary incisors is unchanged, while the mandibular incisors are slightly proclined, from 85.5” to 88” to the mandibular plane. The maxillary incisors have increased from 8 mm to 13 mm relative to the
Fig. 8. Intraoral photographs, Aprii 1987.
62
A m . S. Orthod. Dentofac. Orthop. September 1989
Dunbar, Goldin, and Subtelny
Fig. 8 (Cont’d). Study models, April 1987.
APo plane (mean 5.7 mm). The interincisal angle has become more acute, decreasing from 127” to 122” (mean 131.9”) (Fig. 6 and Tab!e I). Final evaluation Both skeletal and dental improvements have occurred over time. The growth of the mandible and the maxilla has
remained fairly consistent, relative to each other, with mandibular growth slightly ahead. The angle of facial convexity is essentially unchanged at - 25”, with the maxillary anteroposterior dimension keeping pace with the mandibular growth. The maxillary incisors have retroclined slightly; the mandibular incisors appear to have prochned slightly. The maxillary incisal edge to APO plane has decreased 2 mm to
CONCLUSION
A very acceptable occlusion has been achieved in a patient with poor growth potential. The results were obtained without extraction in the maxillary arch although severe arch length discrepancy was present. A single tooth extraction in the lower arch enabled correction of arch length problems and achievement of an acceptable overjet. Approximately 3 years postretention: the occlusion has remained relatively stable, with a bonded fixed lower and removable upper retainers. We wish to express our sincere gratitude to tbe orthodontic residents of the Eastman Dental Center who participated in the treatment of this case. Fig. 9. Superimposition tracing, November 1984, April 1987.
I1 mm; the mandibular incisors are 8.5 mm ahead of the APO plane, an increase of 0.5 mm. The angulation of the mandibular plane is unchanged from the initial records (Figs. 7 through 9 and Table I).
Reprint requests to: Dr. Bruce Goldin Eastman Dental Center Department of Orthodontics 625 Elmwood Ave. Rochester, NY 14620
n
o~~~tio~ of Class I crowding in an achondyoplastic patient d. Patrick Dunbar, DDS, Bruce Goldin, PhD, DMD, and d. Daniel Subtelny, DDS, Rochester, N.Y.
n the treatment of any malocclusion, the orthodontist needs to consider many factors including the growth potential of the patient. In cases in which growth may be intenupted or deficient because of genetic factors, special attention must be given. Treatment modalities may be limited since “normal” growth cannot be used as a positive treatment factor.
Diagnosis The patient had a Class I malocclusion with severe maxillary retrnsion and decreased maxillary vertical height. The anterior palate was tipped up. There was maxillary anterior crowding with both lateral incisors in crossbite. The left buccal segment was also in crossbite. The lower arch exhibited moderate anterior crowding. This patient had large adenoids but was a nasal breather. Her previous mandibular positioning was direct horizontally as a result of overclosure (Fig. 1). From the Eastman Dental Center. Presented to the American Board of Orthodontics in partial fulfdlment of the requirements for the certification process conducted by the Board. 8/4/11458
History
The patient, a girl 11 years 4 months of age, was first seen with achondroplasia. A tonsillectomy and myringotomy with tube insertion were performed at age 5 years. The patient was an otherwise well-adjusted, healthy, and intelligent person. Facial appearance Typical of achondroplasia, the patient exhibited a concave soft-tissue profile with a bulging forehead and a retrognathic maxilla. The nose was saddle-shaped in appearance because of lack of development of the nasomaxillary complex. There were no apparent major asymmetries judging from both the lateral and frontal photographs (Fig. 2). Etiology
The malocclusion and the facial appearance illustrate genetic characteristics. Achondroplasia is an autosomaldominant trait that equally affects males and females. Its clinical manifestation that is of concern to orthodontists is the effect on the cranial base (chondrocranium), which is cbaracteristically small yet the cranial vault continues to grow, compensafing for the developing brain. Disproportionate growth results.
Fig. 1. Intraoral slides, December 1980.
A m . .I Orthod. Dtwlofic. Orthop. Septemkr I989
Dunbar, Goldin, and Subtelny
Fig. 1 (Cont’d). Study models, December 1980
Gephalometric findings
Skeletally the chin was slightly forward with a facial angle of 87” when compared with the Michigan mean of 84.6” at age 11. The maxilla was positioned posteriorly to nasion with a 79” FH-NA angle (mean 88”). The profile was concave with a - 12” angle of convexity. Radiographic evaluation of the adenoids showed approximately 75% airway obstruction. The
frontal radiograph showed slight maxillary constriction. Nasal width was within normal limits, bnt cloudiness in the airway was apparent. The denture bases basically mirrored their skeleta; bases with an SNB of 81” (mean 77.3”), an SNA of 74” (mean 81. l”), and an ANB of 7” (mean 3.8”). These findings, along with an A-B/NPg of 6” (mean -5.9”): indicated a poor
Fig. 2. Facial photographs, December 1980.
C Fig. 3. Cephalometric tracings. A, Initial tracing, December 1980. B, Retention tracing, November
1984. C, Postretention tracing, April 1987.
Am. .;. mkd. Drntofac. Ortlwp.
Dunbar, Goldin, and Subtelny
September
1989
Fig. 4. Facial photographs, November 1984.
able I. Gephalometric
findings
Initial Measurement , Facial angle (“) NA-FH (“) Angel of convexity (“) MP angle (“) SNA (“) SNB (“) Y axis (“) N-ANS (mm) N-ME (mm) UFH/TFH(%) Interincisal angle (“) Upper 1 -paIatal plane (“) Upper I-FH (“) Lower I-MP (“) Lower I-AP angular (“) Upper LAP iinear (mm) Lower I-AP linear (nun)
I2180
Mean Michigan-l I yr
Retention 11184
Postretention 4187
Mean Michigan-16 yr
87.0 79.0 -12.0
84.6 88.0 6.6
86.0 88.0 -15.5
88.0 79.0 -15.0
26.0 74.0 81.0 59.0 38.0 106.0 35.8 127.0
28.8 77.3 60.6 52.7 116.2 45.3 126.9
27.5 73.0 81.0 61.5 41.0 34.7 122.0
26.0 75.0 82.0 60.0 41.0 119.0 34.4 122.0
79.2 59.6 55.1 123.2 45.2 133.6
114.0
112.8
113.5
111.0
Ill.!
122.0 -4.5 16.0
112.5 3.3 22.5
123.0 -2.0 29.0
122.0 0.0 31.0
111.1
8.0
6.5
13.0
10.5
5.2
5.5
1.6
8.0
8.0
0.8
81.1
denture base relationship to each other and an abnormal skeleta1 profile. The vertical dimension showed decreased upper facial to totai facial height attributable in part to the palatal plane being
118.1
86.0 87.9 3.2 25.8
$1.8
5.2 21.8
tipped up anteriorly. The mandibular plane was slightly 9at relative to the mean, 26” versus a mean of 28.8“. Dentally the maxillary incisors were prochned relative to the SN plane and Frankfort horizontal plane, ? 16.5” and 122”,
Volume 96 Number 3
Fig. 5. Study models at retention, November 1984.
respectively, with means of 105.1” and 112.5”. Relative to the palatal plane, the upper incisor was well related due to the upward anterior palatal tilt. The mandibular incisors were slightly retroclined relative to the mandibular plane at 85.5” (mean 93.3”). The incisal edges of both maxillary and mandibular incisors were positioned anteriorly relative to the A-PO plane at 8 mm and 5.5 mm, respectively, with means of 6.5 mm and 1.6 mm (Fig. 3 and Table I).
Plan of treatment The initial plan was to proceed with nonextraction therapy. A fixed Hyrax rapid palatal developer was to be used to expand the maxilla, correct the left posterior crossbite, and gain arch length. Occlusal acrylic overlays were to be integrated with the Hyrax and placed over the maxillary first and second molars to help prevent buccal flaring of these teeth during expansion. Nasomaxillary advancement was to be accomplished with fixed appliances incorporating anterior labial
A m . 2. Orthod. Demfac.Orthop. September 1989
Dunbar, Goldin, and Subtelny
root torque and fabce mask therapy. A lip bumper was to be used in the lower arch to upright the first and second molars, gain arch length, and slightly open the mandibular plane to decrease the skeletal concavity. The possible need for a lower arch extraction was left for reevaluation, depending on t h e outcome of ongoing treatment. progress 06 treatment
A Hyrax rapid palatal expansion appliance with occlusal acrylic coverage was cemented to the first premolars and first molars. Activation was discontinued 14 days later and the
achieved changes were stabilized after 2.5 mm of expansion with correction of the buccal crossbite. At that time the maxillary incisor brackets were bonded and arch wires fabricated with anterior labial root torque to advance me maxillary incisors. After 6 months of treatment, a maxillary holding appliance was placed. The patient stated that nasal breaking was much easier. A lip bumper was placed to the lower first molars. Biteblocks off the maxillary holding appliance were used to decrease the possibility of bite opening as the lower molars uprighted. Face mask therapy was added 8 months into treatment to stimulate anterior positioning of the nasomaxillary complex. The face mask was discontinued after 2 months when sufficient space for the maxillary lateral incisors was gained. The maxillary canines were then brought into the arch. A palatal holding appliance with rotation loops was fixed to the maxillary second molars 15 months into treatment to hold eruption and gain better mesial-buccal molar rotation. After 24 months of treatment, it was decided to extract a lower lateral incisor because of deficient anterior arch length. The spaces were closed by use of power chain modules. Forty-two months after initiation of active treatment, appliances were removed. A maxillary edgewise Hawley retainer and a lower lingual bonded 3-3 fixed retamer were placed. Results achieved
~ 6. Superimposition tracing, December 1980, November 4984.
Facial. The lateral views show a profile that is still concave in appearance. However, the concavity s e e m s t o have remained stable without worsening (Fig. 4).
Fig. 7. Facial photographs, April 1987.
Volume 96 Number 3
Dental. A super Class I molar relationship with a Class III tendency at the canines has resulted. This is primarily attributable to a deficient maxilla. All teeth are in the arch and in good alignment (Fig. 5). Cephalometric analysis at retention. At age 15, the chin to forehead relationship has remained relatively stable and now is slightly posterior to the Downs mean, 86” versus a mean of 87.2”. The anteroposterior position of the maxilla has decreased 2” to 77” for the FH-NA angle; the angle of facial convexity has become slightly more concave. The man-
dibular plane has remained reasonably stable with an increase of 1.5”. The vertical dimension has remained relatively constant, although the maxilla appears to have moved slightly inferiorly relative to the anterior tubercle of the atlas. The upper facial height to total facial height ratio is virtually unchanged. Dentally the proclination of the maxillary incisors is unchanged, while the mandibular incisors are slightly proclined, from 85.5” to 88” to the mandibular plane. The maxillary incisors have increased from 8 mm to 13 mm relative to the
Fig. 8. Intraoral photographs, Aprii 1987.
62
A m . S. Orthod. Dentofac. Orthop. September 1989
Dunbar, Goldin, and Subtelny
Fig. 8 (Cont’d). Study models, April 1987.
APo plane (mean 5.7 mm). The interincisal angle has become more acute, decreasing from 127” to 122” (mean 131.9”) (Fig. 6 and Tab!e I). Final evaluation Both skeletal and dental improvements have occurred over time. The growth of the mandible and the maxilla has
remained fairly consistent, relative to each other, with mandibular growth slightly ahead. The angle of facial convexity is essentially unchanged at - 25”, with the maxillary anteroposterior dimension keeping pace with the mandibular growth. The maxillary incisors have retroclined slightly; the mandibular incisors appear to have prochned slightly. The maxillary incisal edge to APO plane has decreased 2 mm to
CONCLUSION
A very acceptable occlusion has been achieved in a patient with poor growth potential. The results were obtained without extraction in the maxillary arch although severe arch length discrepancy was present. A single tooth extraction in the lower arch enabled correction of arch length problems and achievement of an acceptable overjet. Approximately 3 years postretention: the occlusion has remained relatively stable, with a bonded fixed lower and removable upper retainers. We wish to express our sincere gratitude to tbe orthodontic residents of the Eastman Dental Center who participated in the treatment of this case. Fig. 9. Superimposition tracing, November 1984, April 1987.
I1 mm; the mandibular incisors are 8.5 mm ahead of the APO plane, an increase of 0.5 mm. The angulation of the mandibular plane is unchanged from the initial records (Figs. 7 through 9 and Table I).
Reprint requests to: Dr. Bruce Goldin Eastman Dental Center Department of Orthodontics 625 Elmwood Ave. Rochester, NY 14620