Anterior maxillary distraction osteogenesis
Anterior maxillary distraction osteogenesis for cleft lip and
palate
Distraction osteogenesis (DO) has become a mainstream surgical technique for patients
with jaw deformities. This case report describes the surgical orthodontic treatment of
maxillary hypoplasia in two patients of 14–19 years with cleft lip and palate. They were
treated with anterior maxillary DO using rigid intraoral distractor device. Distraction was
started after the initial latency period with activation of 0.8 mm/day until positive overjet
was gained. Cephalometric analysis was performed twice for evaluation: Before surgery
(Pre-Rx) and after distraction (Post-Rx). Both the distractions completed smoothly and
maxilla was distracted efficiently. Maxillary prominence increased in both the patients
with a positive overjet after distraction. DO provided an effective way to correct maxillary
hypoplasia secondary to cleft lip and palate.
Introduction
Cleft palate is one of the most prevalent congenital craniofacial
birth defects in human. In general, the palatoplasty and
pharyngoplasty are performed on such patients at an early age
to obtain good velopharyngeal closure.
As early as 1954,
Herfert suggested that the palatoplasty could damage the growth
center of maxilla, thus interfering with the maxillofacial growth,
leading to hypoplasia. Bardach and Kelly indicated that severe
interference of the maxillary growth usually is caused by the
contraction of the scar on the palate.
Recently, distraction osteogenesis (DO) has evolved as a
new mainstream surgical technique for patients with such jaw
deformities. It can be performed on both the mandible and the
maxilla. Maxillary DO was proposed in 1997 using a rigid external
distraction device. DO can provide skeletal advancement along
with expansion of soft tissue and is regarded as highly effective
surgical technique for patients with jaw deformities.
DO has shown excellent results in maintaining stability. DO
outweighs the traditional methods of craniofacial reconstruction by its
ability to generate new bone and reduced morbidity rate. In addition,
advancement by DO is not as limited as conventional osteotomies
Treatment objective
The objective was to correct the following parameters:
• Hypoplastic maxilla by forward repositioning
• Anterior and posterior crossbites
• Reverse overjet and overbite
• Molar and canine relationship.
Treatment alternatives
Anterior movement of maxilla by Le Fort 1 orthognathic
surgery was an alternative treatment for these cases. However,
due to the possibility of aggravation of hypernasality in the
patients after Le Fort 1 osteotomy, DO of anterior maxilla
was chosen as the treatment plan. The reason is that the
velopharyngeal area will remain intact after the anterior DO
procedure.
Surgical procedure
Vertical cuts were made between two premolars on either
side. Horizontal cuts were made in a fashion similar to that of
conventional Le Forte 1 osteotomy in both the cases. Down
fracture of the premaxilla was done. After complete mobilization
of the premaxilla, the appliance was cemented into the mouth and
surgical site was closed using sutures.
Distraction protocol
The distraction procedure was initiated after 5 days of the surgery.
The distractor was activated twice per day with two turns per
activation giving a total distraction of 0.8 mm/day. Patients were
recalled after every 3 days. Distraction was discontinued after
attaining the desired overjet. 8 weeks of consolidation period
was maintained and hyrax appliance was removed only after
callus formation was confirmed on the radiograph.
Cleft lip and palate patients show sagittal hypoplasia of maxilla
and speech disorders. Various reasons are liable for maxillary
constriction, such as tension of scars, teeth agenesis, and poorly
reconstructed nasolabial muscles. Maxillary DO is often
employed for correction of maxillary hypoplasia in patients with
cleft lip and palate. The intraoral distractor offers some benefits
such as less psychological stress and shorter hospitalization period
and does not necessarily require patient’s cooperation during the
retention period. As compared to the extraoral distraction, it does
not leave scars caused by fixation screws.
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| case 1 pre and post operative |
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| case 2 pre and post operative |
This case report demonstrates increase in SNA angle in both
the patients following surgery in accordance with maxillary
advancement. Alkhouri et al. reported similar findings in patients
with unilateral cleft lip and palate.
The use of banded type of
the anteroposterior expansion might have led to the extrusion
of molars as a result of which Y-axis seemed to increase in both
the cases after distraction. Similarly, as a result of extrusion of
the maxillary molars, there was clockwise rotation of mandible,
leading to posterior positioning of Point B seen in both the cases.
SN-PP, which represents the inclination of palatal plane, was
decreased showing a tendency toward open bite as seen in both
the cases clinically. Nv to Point A depicted a decrease in value
indicating forward movement of maxilla whereas and Nv to Pog
demonstrated an increase in the negative value.
Srivastava et al. reported an increase in U1 to SN value
following distraction therapy which was not in correlation with
our study as the ongoing orthodontic treatment resulted in
retroclination of upper incisors rather than proclination UI
to NA angular measurements decreased demonstrating decrease
in proclination and the linear measurement also decreased
showing the forward movement of Point A following the surgery.
There was a significant reduction in overjet of both the patients
decreasing their Class III tendency.
Hence, maxillary advancement is essential to improve the
esthetic profile and functional occlusal relationship. Many
other studies have evaluated the effectiveness of DO in the
treatment of cleft lip and palate patients suffering from maxillary
deficiency.
The pitfall of the surgery is the lack of vector control and
development of an anterior open bite.
Conclusion
AMOD is a good therapeutic procedure to relish the esthetic
improvement and establish a good occlusal relationship. Its
ability to increase the palatal and arch length, preservation of
palatopharyngeal closure function, and reduction in the relapse
rate, anterior maxillary segmental distraction has great value in the
treatment of maxillary hypoplasia secondary to cleft lip and palate.
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