Treatment of a Class II, Division 1 vertical growth pattern with severe anterior crowding

Treatment of a Class II, Division 1 vertical growth pattern with severe anterior crowding

AMERICAN BOARD OF ORTHODONTICS CASE REPORT Treatment of a Class II, Division 1 vertical growth pattern with severe anterior crowding Ernest A. Maggio...

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AMERICAN BOARD OF ORTHODONTICS CASE REPORT

Treatment of a Class II, Division 1 vertical growth pattern with severe anterior crowding Ernest A. Maggioncalda, DDS*

San Francisco, Calif. Treatment of a skeletodental Class II vertical growth problem, combined with a severe arch length deficiency in both arches, presents a challenging orthodontic problem. This is the case report of a small-statured, 11-year, 10-month-old boy with a history of juvenile chronic arthritis and marked mandibular retrognathia who was treated with first premolar extractions in both arches. Unexpected favorable growth, with significant decrease of the mandibular plane angle over a long treatment period, provided a very satisfactory result. [This case report was presented to the American Board of Orthodontics in partial fulfillment of the requirements for the certification process.] (Am J Orthod Dentofac Orthop 1997;112:300-8.)

A l l Class II malocclusions present a challenge to the orthodontist; each requires a treatment regimen specifically designed for the individual patient. The degree of difficulty with Class II treatment varies with accompanying disorders, which may include medical, dental, and skeletal structure; hereditary factors; growth trends; the influence of environmental factors; or any combination of the above. Attempting to treat all patients with Class II malocclusions with "cookbook" treatment criteria often leads to a compromised result, or perhaps total failure. This is especially important as most problems seen by orthodontists are of the Class II variety. Careful diagnosis helps reveal subtle discrepancies that may require alterations in the treatment plan. Lack of success in treating these severe malocclusions may not always be attributable to poor patient cooperation--rather, it can be attributed to poor diagnosis before and during treatment. A patient's growth potential is an important consideration for successful orthodontic correction of a Class II skeletodental pattern. More precisely, it is amount and direction of facial skeletal growth that greatly facilitates correction during orthodontic therapy. Anticipated growth of a child or completion of growth in adults often dictates treatment objectives and limitations, including timing of treatment, dental extraction patterns, appliance design, and, at times, orthognathic surgery. Specific appliance therapy for each patient evolves from specific diagnostic interpretation. Even when adhering to sound treatment principles, the very best effort by *Associate professor, Department of Orthodontics, University of the Pacific School of Dentistry, San Francisco. Reprint requests to: Dr. Ernest Maggioncalda, 4943 Junipero Serra Blvd., Daly City, CA 94014-3216. Copyright © 1997 by the American Association of Orthodontists. 0889-5406/97/$5.00 + 0 8/4/72963

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the clinician and patient may still result in a compromise of some extremely challenging deformities during treatment. However, there are fortuitous occasions when the clinician finds unexpectedly favorable growth patterns in some patients, which make a very satisfying result possible. The following case report will illustrate the treatment of a challenging Class II, Division 1 steep mandibular plane angle malocclusion with severe crowding in both arches, during which unpredictable favorable growth occurred. CASE REPORT Patient History and General Clinical Picture

History. The patient was a white boy, 11 years, 10 months of age. A medical history of juvenile chronic arthritis was reported, although the patient appeared healthy at the initial examination with no conditions present what would contraindicate treatment. No nasal obstruction or allergies that might have contributed to the malocclusion were noted. The patient's chief complaint was "crowded upper and lower front teeth." General body size and stature appeared small for the patient's age group. Oral tissues were healthy, with no carious lesions apparent. Oral hygiene was very good, and no detrimental habits were noted that might have affected tooth position. Photographic analysis. There is fullness of the upper lip in profile, with an acute nasolabial fold (Fig. 1). Sulcus depth of the fold is lacking and at about 90°. The upper lip is 4 mm forward of Rickett's E-plane. The mentolabial sulcus is shallow, with the lower lip 1 mm forward of the E-plane. There is lip incompetence in repose, with mentalis strain on closure. The frontal view reveals a symmetrical face with dolicocephalic tendencies. OccIusal analysis. Occlusal analysis (Figs. 2 and 3) shows retained maxillary right and left deciduous second molars and the mandibular left deciduous second molar.

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Fig. 1. Pretreatment frontal and profile photographs.

Fig. 2. Pretreatment intraoral photographs.

The permanent first molar occlusal relationship is end-on Class II and would be a full Class II relationship with loss of maxillary deciduous second molars and closure of the leeway space. Maxillary incisor overjet is 9.5 mm, measured from the labial surface of the mandibular left central incisor to the labial surface of the maxillary left central incisor. The overbite is 3 mm. There is a severe arch length discrepancy, with all canines blocked out. Maxillary arch form is narrow and tapered, particularly in the premolar area. Both maxillary lateral incisors are displaced lingually and are essentially nonfunctional, as are all the canines. The mandibular anterior segment is flattened somewhat from canine to canine and some lingual angulation of incisors is evident. Maxillary and mandibular arch form are not well coordinated. There is a slight dental midline deviation, with the lower midline off 1 mm to the left.

Radiographic analysis. Pretreatment radiographic examination (Fig. 4) shows a normal complement of permanent teeth, including four third molars buds. The unerupted mandibular left second premolar is mesially inclined. Mandibular incisor root apices converge and incisor roots are in close approximation. All are present. Tooth and bone anatomy are unremarkable. Cephalometric evaluation. Cephalometric radiographic values (Table I) show excessive lower facial height (56.3%) with a relatively steep mandibular plane angle (GoGnSn 38°). Cephalometric tracings (Fig. 5) indicate a Class II skeletal pattern. The ANB angle was 6° with an SNB angle of 74 °. The anteroposterior position of the mandibular incisors relative to the apical base appears to be within normal limits, even though significant crowding exists. Maxillary incisors are anterior to the apical base at 9 mm (1 to NA). The I M P A is 90 ° and mandibular incisor

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Fig. 3. Initial study models. to APO is 2 mm. There is marked mandibular retrognathia, short posterior facial height, and excessive lower anterior facial height. ETIOLOGIC FACTORS

An excessive vertical growth pattern with severe anterior crowding in both arches is genetic. The growth pattern is accompanied by developmental dental and dentoalveolar compensations, due to narrowed arch form. The malocclusion is due primarily to a skeletal discrepancy between the maxilla and the mandible, A history of chronic juvenile arthritis may have detrimentally altered condylar growth at an early age; however, no radiographs are available to confirm this possibility. DIAGNOSIS

The patient presented with a Class II, Division 1 malocclusion in the late mixed dentition, with mandibular retrognathia, a steep mandibular plane angle, and an obtuse gonial angle with antegonial notching (Fig. 5). Posterior facial height was short, and anterior facial height

moderately excessive. Severe crowding in both maxillary and mandibular anterior segments mitigated against acceptable incisor and canine alignment in both arches. Retained deciduous teeth created an end-on molar relationship. A history of juvenile chronic arthritis was noted. It is inconclusive as to whether this disorder had a significant bearing on the growth pattern. TREATMENT OBJECTIVES

Maxilla: Maintain anteroposterior position of Point A. Use high-pull headgear to restrain forward growth and avoid orthodontically induced posterior dentoalveolar height increase. Mandible: Encourage full potential of forward mandibular growth; prognosis guarded because of initial skeletal discrepancy. Maxillary dentition: Attempt some distalization of the first molars to achieve Class I occlusion and arch length enhancement; extraction of first premolars for anterior alignment with uprighting and retrac-

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Fig. 4. Pretreatment intraoral radiographs.

tion of proclined central incisors; move blocked out canines into arch; improve arch form compatibility with mandibular arch. Mandibular dentition: Extraction of both first premolars for anterior alignment; move blocked out canines into arch; coordinate arch form with maxillary arch as Class II relationship is corrected. Facial esthetics: Reduce facial convexity by facilitating forward mandibular growth and restraining maxillary growth with high-pull headgear; enhance nasolabial fold by retraction of maxillary incisors; maintain, or decrease if possible, lower facial height; improve lip posture and seal; increase maxillary incisor to stomion dimension. Occlusion: Establish Class I molar and canine relationship; achieve optimal overjet and overbite; maintain some curve of Spee but avoid the extrusion of the maxillary second molars; achieve ideal arch coordination with canine disclusion; increase interincisal angle by uprighting the maxillary incisors.

TREATMENT PLAN Treatment was initiated after extraction of all four first premolars and three retained deciduous second molars. An edgewise pretipped and pretorqued 0.018 × 0.025 slot appliance was placed. High-pull headgear was used to increase molar anchorage in the maxillary arch, and a fixed 0.032 stainless steel lingual arch was placed in both

Table I. Summary of cephalometric analysis Measurement

Norm

A

B

SNA SNB ANB NA to point A (ram) GoGnSN NPO-FH IMPA FMA

82 80 2 2 32 88 90 25

80 74 6 2 38 86 90 26.5

80 76.5 3.5 2 32 89 101 21

LI-APO (ram) UI-NA UI-NA (mm) LI-NB LI-NB (mrn) Y-axis SN-OP Interincisalangle E Plane--U to L lip Holdawayratio LAFH (%)

0-2 22 4 25 4 59 14 131 -1/-2 4/4 54

2 29 7 21 4 58 26.5 127 4/1 4/- 1 56.3

5 25 5 30 7 56.5 20 125 -5/-6 7/3 57

maxillary and mandibular arches. The patient was instructed to wear headgear a minimum of 14 to 16 hours daily. Initially, brackets were not placed on the maxillary and mandibular incisors. After the posterior segments were leveled, all canines were retracted with sectional retraction springs (0.016 × 0.022, stainless steel T-scissor loop design). Both maxillary canines were retracted before the mandibular canines to obtain a Class I canine relationship early in treatment. Brackets were later bonded to all the incisors, and both arches were leveled

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Fig. 5. Pretreatment Lateral cephalogram and tracing.

Fig. 6. Posttreatment frontal and profile photographs.

with 0.016 × 0.022 stainless steel arch wires. Maxillary and mandibular spaces were closed with continuous 0.016 × 0.022 stainless steel multilooped arch wires. Intermaxillary Class II elastic traction was limited to avoid increasing the vertical dimension through lower molar extrusion. The occlusion was detailed and finished with 0.016 × 0.022 maxillary and 0.0175 × 0.025 mandibular stainless steel arch wires. TREATMENT PROGRESS Good patient headgear compliance was noted during the first few months of treatment, but there was a decrease in compliance thereafter. Ongoing reinforcement discussions provided some improvement, but continued compliance with the headgear was sporadic, even though several parent consultations were necessary. Thereafter, the patient was placed on a 2-week office visit schedule to observe progress and to manage compliance more closely. Sectional retraction of all canines required approximately 4 months. Eruption of all second molars was very slow, and brackets were bonded to these teeth 25 months into active treatment. Both arches were releveled. It was noted

that the molar relationship was still end-on Class II at that time. The patient was instructed that there would be no attempt to retract anterior teeth unless he increased time with headgear wear because a Class I molar relationship was essential before anterior segment retraction. Progress was exceedingly slow for several months, but favorable change eventually became evident because of more headgear wear and remarkable skeletal growth. Maxillary and mandibular incisor retraction was augmented with V4 inch, 4 ounce, Class II elastic traction during space closure. Headgear was also worn at this time. The maxillary and mandibular arches were releveled. Detailing of tooth positions was accomplished with 0.016 × 0.022 maxillary and 0.0175 × 0.025 mandibular stainless steel arch wires. TREATMENT RESULT Photographic analysis. Improved facial balance (Fig. 6) was achieved as a result of reduction of facial convexity by maxillary incisor retraction and horizontal mandibular growth, with upward and forward rotation. There remained some degree of lip incompetency in the final result; however, lip posture was improved. Nasolabial and

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Fig. 7, Posttreatment intraoral photographs.

mentolabial sulcus depth was shallow; the upper lip contour was improved by nasal growth and incisor retraction. A slight increase in posttreatment lower anterior facial height was apparent, 56.3% to 57%. Occlusal analysis. A Class I occlusion with satisfactory overjet and overbite and a well-seated posterior occlusion were achieved (Figs. 7 and 8). The maxillary and mandibular intraarch discrepancies were essentially eliminated and improved arch coordination provided functional mandibular movements within normal limits. Dental and facial midlines coincided, and canine guidance existed in both right and left excursions, with no balancing interferences noted. No mandibular deviation was noted on opening and closing. The curve of Spee was maintained through first and second molar segments. Centric occlusion and centric relation were coincident. Radiographic analysis. Posttreatment intraoral radiographs (Fig. 9) revealed satisfactory root position, with minor apical blunting in the maxillary incisor segment. Alveolar bone height appeared to be within normal limits. There was insufficient arch length for all third molars, and the patient was later referred for removal of these teeth. Cephalometric evaluation. There was a decrease in the ANB angle from 6° to 3.5 °, with a significant decrease in the GoGnSN angle from 38 ° to 32 °. A reduction in facial convexity is also apparent (Fig. 10). Cephalometric anal-

ysis (Table I) with superimposition of pretreatment and posttreatment radiographs (Fig. 11, A) revealed no apparent vertical change in point A relative to cranial base, even though the S-NA line increased in length 6 mm with growth. The SNA angle remained at 80 ° and maxillary superimposition revealed a much greater vertical increase in posterior dentoalveolar height than in anterior height. There was some posterior downward tipping of palatal plane. Overall growth of the maxilla was downward and forward. In the mandible, there was a 2.5 ° advance in the SNB angle, with approximately 15 mm of forward growth at pogonion. A significant change in the growth pattern was noted with an increase in posterior facial height. There was a greater increase in mandibular posterior dentoalveolar height than in the corresponding anterior region, and proportionally much more than the increase seen in the maxillary posterior segment. The total ANB angle change appears to be due to forward mandibular growth. The facial plane angle, NPO-FH, increased from 86° to 89 °, suggesting a significant degree of horizontal mandibular growth. Maxillary incisor angulation, 29 ° to NA, decreased with incisor retraction to the 25 °. Mesial movement of the maxillary molars during space closure was 8 mm (Fig. 11, B). In the mandible, incisor angulation to the NB line increased from 21 ° to 30 °, significantly beyond Steiner's 25 ° mean. A final IMPA of 101 ° exceeded Tweed's 90 ° val-

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Fig. 8. Posttreatment study models.

ue (Fig. 11, B). The mandibular incisors came forward 3 mm to the NB line. There was 7 mm of mesial mandibular molar movement during space closure. RETENTION

After completion of active treatment and removal of maxillary and mandibular appliances, a maxillary circumferential removable retainer was used along with a mandibular fixed canine-to-canine bonded 0.0175 multistranded wire. Total retention time was 2 years. At the last visit, the patient was advised to continue to wear the retainers during sleeping hours for an additional 6 months. Very satisfactory retainer wear was observed during the 2 year postactive treatment period.

FINAL EVALUATION

The overall change in skeletal and dental relationships was profound. Dental and facial esthetics improved markedly as a result of treatment and growth. The mandibular plane angle decreased more than expected. Excellent growth in corpus length and ramus height helped to reduce the Class II skeletodental discrepancy. The limiting effect of high-pull headgear on maxillary posterior alveolar height may have been a contributing factor. Occlusal analysis revealed slightly insufficient maxillary second molar transverse width, particularly on the left side, but this problem has improved over time with further settling of the second molars. Mild labial gingival recession around the mandibular left lateral

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Fig. 9. Posttreatment panoral and intraoral radiographs. Note lower third molar position.

Fig. 10. Posttreatment lateral cephalogram and tracing.

incisor and canine was apparent. This recession may have been due to thin labial bone and/or labial incisor tipping. However, the gingival attachment on both teeth was within normal limits when probed. Prognosis of rotation corrections in both anterior segments remains guarded. All third molars were extracted before cessation of retainer wear. The final head film was taken after extraction of third molars. Poor headgear wear, combined with a very late growth spurt, possibly influenced by an earlier

arthritic developmental condylar disorder associated with juvenile chronic arthritis, lengthened treatment excessively. Fortunately, for this patient, a great deal of favorable mandibular, as well as general skeletal growth, manifested itself during the active treatment period, albeit late. DISCUSSION

Juvenile chronic arthritis (JCA), which begins before 16 years of age, can be divided into three

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)

'\

A

B

11 vrs 10 mo

11 yrs 10 mo - -

. . . . . . . .

17yrs 3mo

.......

:-"2;:" i j

t~"5

17 yrs 3 mo

Fig. 11. Superimposed cephalometric tracings. A, Full tracings. B, Maxilla and mandible. Initial tracing at 11 years, 10 months. Final tracing at 17 years, 3 months.

subtypes (systemic, pauciarticular, polyarticular). Each type presents with different clinical features. Larger joints, including the condyle, tend to be affected by the disease. The result is an interference with normal growth and development. Micrognathia, due to impaired condylar growth, is seen in more than 60% of patients with the disorder. 1 Although information was not available as to which subtype of JCA was present in this patient, the literature states that when JCA occurs in the preteen years, the outlook is more favorable than when it is found in adults. Fortunately, complete remission occurs in up to 75% of patients. This information may provide insight into the significant increase in growth and morphologic change seen in the patient's mandible during the period of his orthodontic treatment. A 6° decrease in GoGnSn, although very favorable for this patient's orthodontic treatment result, is unusual with or without orthodontic therapy. Brodie claimed that the morphogenetic pattern of the human skull is established at an early age (6 months to 1 year) and that once it is attained, it does not change. However, Bj6rk's implant studies have shown great individual variation in the normal growth pattern of the lower jaw. 2 In addition, extrusion of posterior teeth with appliances can alter a normal growth pattern, essentially negating any favorable horizontal effect of condylar growth. According to other investigators, 3 deep (+3 ram) antegonial notching (seen on cephalometric

radiograph, Fig. 5) predicates a backward pattern of mandibular rotation and a vertical direction of mandibular growth. There is evidence that "deep notch" patients require a longer duration of orthodontic treatment due to an unfavorable mandibular growth pattern. They generally have a smaller increase in total length and corpus length, with less forward chin displacement. These patients also exhibit longer total facial height and longer lower facial height than "shallow notch" (1 mm or less) subjects. The mandibular plane angle is also more vertically directed with growth. One explanation for the favorable result for this patient may be "catch-up" growth rate at the condyles that were possibly affected early by a temporary arthritic disorder. There is evidence to support the catch-up growth hypothesis if a disturbance occurs before intense hyperplastic activity (pubertal growth spurt). Irreversible damage is less apt to occur during the juvenile period of growth if there is complete remission of the disorder, permitting expression of an inherent, genetically normal growth pattern for this patient. REFERENCES 1. Kjellber H, Fasth A, Kiliaridis S, Wenneberg B, Thilander B. Craniofacial structure in children with juvenile chronic arthritis (JCA) compared with healthy children with ideal or postnormal occlusion. Am J Orthod Dentofac Orthod 1995;107:67-77 2. Bj6rk A. Variations in the growth pattern of the human mandible: longitudinal radiographic study by the implant method. J Dent Res 1963;42:400-11. 3. ginger CP, Mamandras AH, Hunter WS. The depth of the mandibular antegonial notch as an indicator of mandibular growth potential. Am J Orthod Dentofac Orthop 1987;91:117-24.