Raghu Devanna. MDS
Department of Orthodontics & Dentofacial Orthopedics,
A.M.E’s Dental college & Hospital,
Sagittal and transverse discrepancies often coexist in skeletal Class II malocclusions. Orthopedic growth modification can work well in such cases, provided that the remaining pubertal growth is adequate and that the clinician can time treatment to coincide with the peak growth period.
The transverse discrepancy is generally corrected first, establishing a proper base for the sagittal correction to follow. For example, in a skeletal Class II case with a narrow maxillary arch and retrusive mandible, maxillary expansion is performed initially to facilitate functional mandibular advancement. The present article illustrates an exception to this rule, in a case where sagittal correction was undertaken before transverse correction to make optimal use of the patient’s pubertal growth spurt in first phase followed by a second phase of fixed appliance therapy during adolescence to achieve optimal results.
Keywords: Growing skeletal class II, “Two Phase” Management, Pubertal growth spurt, Orthodontics and Dentofacial Orthopedics.
Whatever the type of appliance that is used or the kind of growth effect that is desired; if growth is to be modified, the patient has to be growing. Growth modification must be done before the adolescent growth spurt ends. In theory, it could be done at any point up to that time. The ideal timing remains somewhat controversial but the recent research has clarified the indications for treatment at various ages. Unfortunately, although most anterior-posterior and vertical jaw discrepancies can be corrected during the primary dentition years, relapse occurs because of continued growth in the original disproportionate pattern. If children are treated very early; they usually need further treatment during the mixed dentition and again in the early permanent dentition to maintain the correction. For all practical purposes, early orthodontic treatment for skeletal problems is mixed dentition treatment; and a second phase of treatment during adolescence will be required1. Sagittal and transverse discrepancies often coexist in skeletal Class II malocclusions.2-4 Orthopedic growth modification can work well in such cases, provided that the remaining pubertal growth is adequate and that the clinician can time treatment to coincide with the peak growth period.5,6
The transverse discrepancy is generally corrected first, establishing a proper base for the sagittal correction to follow.7,8 For example, in a skeletal Class II case with a narrow maxillary arch and retrusive mandible, maxillary expansion is performed initially to facilitate functional mandibular advancement.7,9 The present article illustrates an exception to this rule, in a case where sagittal correction was undertaken before transverse correction to make optimal use of the patient’s pubertal growth spurt in first phase followed by a second phase of fixed appliance therapy during adolescence.
A 12-year-old female presented with the chief complaint of protrusive upper front teeth. She exhibited a convex profile, an acute nasolabial angle, a protrusive upper lip, a trapped lower lip, and a deficient chin (Fig. 1A). The incompetent lips, reduced mandibular plane, and excessive incisal exposure and decreased lower anterior facial height all indicated a horizontal growth pattern.
All permanent teeth were present except for the unerupted third molars. The canine and incisor relationships were Class II. The maxillary anterior teeth were severely proclined, and the overbite was excessive (13mm and 5mm respectively). Midlines were coincident (Fig. 1B). Cephalometric analysis confirmed the diagnosis of a Class II, division 1 malocclusion on a skeletal Class II base, with a horizontal growth pattern and a marked mandibular retrusion (Table 1). Evaluation of the patient’s hand-wrist and cervical radiographs indicated she was at the peak of the pubertal growth spurt, with considerable growth remaining (Fig.1C & D)
Table 1.CEPHALOMETRIC ANALYSIS
|Maxilla to Cranium|
|N Perp. – Pt. A (mm)||0±1 mm||-1.5mm|
|Eff. Max Length (mm)||92mm|
|Mandible to Cranium|
|N Perp. – Pog (mm)||0 mm||-6mm|
|Eff. Mand. Length (mm)||111mm|
|N Pog – F.H. Angle||90°||86mm|
|Maxilla to Mandible (Skeletal)|
|Wits (mm)||0 mm||2.5mm|
Co Gn – Co A (mm)
|Facial Axis Angle||90°||90°|
|GoGn – SN (Angle)||32°||29°|
|Occlusal to SN Angle||14°||20°|
|UFH : LFH||0.7||0.81|
|PFH : AFH||62.65%||65.78%|
|Sum of Posterior Angles||396±6°||392°|
|UI to NA (Angle)||22°||43°|
|UI to NA (mm)||4 mm||10mm|
|UI to Pt. a Vertical (mm)||5 mm||9.5mm|
|UI to SN (Angle)||102±2°||119°|
When the patient positioned the mandible forward, she showed a good improvement in profile i.e positive VTO (Visual Treatment Objective) (fig. 2).
Because the skeletal discrepancies were in the borderline surgical range, both surgical and nonsurgical treatment plans were considered and presented to the patient. Her refusal of any surgery and, more important, her growth status led us toward a functional-orthopedic approach.
The pubertal growth status of a patient is more critical for sagittal correction10 and because the patient was at the peak of pubertal growth, we decided to carry out the sagittal correction first with a functional orthopedic approach. A fixed Twin Block appliance was chosen to stimulate the forward mandibular growth11, 12. This was to be followed by fixed-appliance therapy for simultaneous intrusion and retraction of the anterior teeth and finishing and detailing of the occlusion.
The Twin Block appliance was fabricated with a 7mm sagittal advancement and a 5mm vertical opening in the premolar region (Fig. 3). The patient was instructed to wear the appliance full-time except during meals and contact sports. After six months of wear, the labial bow was activated to retract the upper incisors into the opened spaces.
After 11 months of good compliance, the patient showed a Class I molar relationship with no dual bite and a considerably improved facial profile. She was then fixed with Twin Block appliance with the same vertical opening, but another 2mm of sagittal advancement. After removal of the appliance, we noted a Class I molar relationship, an overjet of 4mm, and increases of 4mm and 2.5mm in the maxillary intercanine and intermolar widths, respectively. The increased arch width in the canine regions had removed the occlusal interferences and settled the canines into a Class I relationship with adequate buccal clearance (Fig. 4). She practiced upper-lip exercises and an active anterior lip seal throughout the orthopedic treatment period.
MBT-prescription .022” brackets were then bonded. For the first seven months of fixed-appliance therapy, we used a removable transpalatal arch to maintain the vertical anchorage and sagittal expansion at the maxillary first molars, as well as 4.5oz Class II elastics to retain the sagittal correction. A utility arch was placed to intrude and retract the maxillary anterior teeth, closing the spaces (Fig. 5).
After 10 months of fixed appliance treatment, the patient was highly satisfied with the treatment results.
The fixed appliances were debonded for a total treatment time of 24 months (Fig. 6 & 7). The patient wore Hawley retainers and a bonded lingual retainer for one year (Fig.8).
Superimposition of the cephalometric tracings revealed a restriction in maxillary growth and considerable forward movement of the chin, resulting in a harmonious basal relationship (Fig. 9a-9e). Other factors contributing to the correction included sagittal and vertical maintenance of the maxillary molars, intrusion and retraction of the maxillary anterior teeth. And counter clockwise rotation of the occlusal plane.
Although the upper anterior intrusion and increased tonicity of the upper lip reduced the incisal exposure, a complete passive lip seal could not be achieved. On retrospective analysis, however, the treatment plan was justified by the results achieved.
A good esthetic and functional result was achieved for this patient. This was achieved by employing a stepwise functional advancement and two phase treatment protocol that was tailored specifically to this patient’s needs. During the treatment, oral hygiene was continually reinforced and treatment mechanics adjusted to simplify oral hygiene.
This approach took advantage of the patient’s pubertal growth spurt to achieve a sagittal correction that otherwise would have been a missed opportunity. Our case exemplifies the need for individualized treatment planning rather than a cook-book approach in the management of dentofacial deformities.
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