Early Orthopaedic Treatment of Hemifacial Microsomia

The aim of this paper is to report treatment effects of functional therapy in a growing patient affected by hemifacial microsomia (HM). According to Kaban's classification, the patient was classified as grade IIa as she presented all mandibular and temporomandibular joint components and a normal shaped, hypoplastic mandible. The therapeutic approach included the use of an asymmetrical functional activator (AFA) to stimulate the growth of the affected side and consequently to improve symmetry of the mandible and maxillary deficiency. Further effects were the lengthening of the mandibular ramus, restoration of occlusion, and expansion of soft tissues.


Introduction
Hemifacial microsomia (HM) is a congenital craniofacial malformation caused by hypoplasia of anatomical structures deriving from the rst and second branchial arches. As a result, HM involves facial skeleton, soft tissues, ear, and cranial nerves, thus resulting in the absence or insu ciency of these components [1]. Such a congenital malformation is also known as Goldenhar syndrome, craniofacial microsomia, rst and second branchial arch syndrome, otomandibular dysostosis, and lateral facial dysplasia [2].
HM is the second most frequent craniofacial birth defect after cleft lip and palate. Reported incidence varies from 1 case every 3000 to 1 case every 5600 newborns [3].
Males and females are not equally a ected: females are less frequently a ected than males with an estimated ratio of 2 : 3. ere is also a di erence between the a ected sides: a right malformation is more frequent than the left one (ratio: 3 : 2) [4].
Aetiology of this condition is uncertain although the majority of authors suggest the hypothesis of an early hemorrhage from the stapedial artery causing a hematoma in the supplied region. us, di erent phenotypical grades of dysmorphism may occur according to the degree of vascular damage.
Among various classi cation systems proposed, in the present article, we selected and used the classi cation proposed by Kaban [5], which distinguishes the following categories according to the severity of the anatomical anomalies: Type I: hypoplastic temporomandibular joint Type IIa: hypoplastic and abnormal shape of mandibular ramus, condyle, and temporomandibular joint Type IIb: mandibular ramus is hypoplastic and markedly abnormal in form and location, being medial and anterior Type III: absence of mandibular ramus Type IV: mandibular body hypoplasia Treatment of patients depends on the degree of deformity of the facial structures and includes repair of bony asymmetry as well as of soft tissue defects and auricular anomalies [6]. e purpose of this report was to present a nonsurgical approach to treat a young girl a ected by mild type IIa HM, using an asymmetrical functional activator (AFA). Facial examination showed an asymmetry with the typical three-dimensional deformity on the a ected side: on the sagittal dimension, the chin was deviated from the midline; on the vertical plane, the mandibular border was cranially displaced; and on the transversal plane, the face resulted less expanded (Figure 1(a)). e left auricle was hypoplastic ( Figure 2).

Case Report
Both condyles showed appropriate movements, and the maximum mouth opening was at normal range.
Computer tomography (CT) scan revealed a hypoplastic condyle and a de ciency in the ramus height on the a ected side.
Intraoral examination highlighted the typical canting of the occlusal plane, as the reduction in ramus length created the condition for a vertical maxillary growth deciency on the a ected side. Based on clinical and radiographic ndings, a diagnosis of grade IIa HM according to Kaban classi cation was made.
Objectives of treatment planning were (1) to improve mandibular growth in the sagittal and vertical dimension, (2) to free the vertical maxillary growth on the a ected side and to correct the occlusal plane canting, and (3) to improve the overall facial symmetry.
It was decided to delay a mandibular osteodistraction and to try a functional approach using an asymmetrical functional activator (AFA).

Description of the Appliance Design
e AFA has a "hybrid" design, being a combination of the two following functional appliances: biteblock components of the bionator and the vestibular shields of the Frankel appliance on the a ected side (Figures 3 and 4).
On the a ected side, it is necessary to free the vertical growth of the maxilla, maintaining upper and lower teeth apart; thus, the ideal appliance is the Frankel I function regulator. is device maintains the vertical dimension by the means of the buccal shields, avoiding any occlusal contact. Allowing the passive vertical eruption of the upper teeth, the appliance corrects the occlusal plane canting. e soft tissue tension due to the buccal shields improves the stretching and lengthening of the soft tissues too. Buccal shields are supplied with a screw, which is progressively activated in order to increase the vertical dimension.
On the healthy side, an Andresen functional appliance is indicated both to avoid dental eruption and to guide the mandible in the therapeutical position improving the chin symmetry.
e acrylic and the wire elements contribute to create the correct setting for skeletal and dentoalveolar correction by forcing the mandible in the correct position in the three dimensions of the space.

Treatment Procedure and Results
An alginate impression was taken, and a construction wax bite was registered with the mandible in advanced and  2 Case Reports in Dentistry symmetric position in order to bring the chin to the midline and to correct the vertical height de ciency on the a ected side. e functional treatment with AFA began at the age of 4, and it was performed for 30 months with good compliance and nearly full-time wearing of the appliance. After this period, the patient showed a favourable response. Particularly, maxilla-mandibular growth on the malformed side developed su ciently to reestablish normal occlusion and an almost complete facial symmetry, with levelling of the occlusal plane and oral commissure (Figures 1 and 5). e treatment continued for another 6-month period with the patient wearing the appliance only by night. At the age of 7, the active therapy was interrupted, and the patient underwent regular follow-up twice a year in order to monitor facial growth and dental eruption. During this  period, no additional orthodontic or surgical procedures were performed.

Discussion
erapy of HM is still controversial, particularly with regard to the possibility of modifying skeletal discrepancy and of redirecting growth on the a ected side with a functional approach [7,8].
Successful treatment of facial asymmetry by functional appliances in the young child following early fracture of the mandibular condyle has extensively been reported [9][10][11][12][13]. Similarly, topics concerning the growth of the mandible and therapeutic approaches to in uence it have been addressed in numerous clinical and experimental studies [14][15][16][17]. Based on these ndings, patients with a recognizable condylar deformity, such as those in type I and IIa HM, might bene t from functional stimulation in uencing condylar growth [18][19][20].
On the other hand, according to few authors, asymmetry tends to recur after orthopaedic treatment in subjects affected by true HM form, which may later require orthognathic surgical correction of skeletal de ciencies [21][22][23]. Conversely, long-term satisfactory results are more likely to be observed in abnormalities due to trauma, infections, or surgical iatrogenic deformities; these conditions are frequently misdiagnosed as HM, even though they are limited to the bony structure of the mandible without involvement of the soft tissue and neuromuscular pattern [24,25]. e present case demonstrated a good outcome of functional appliance therapy in a growing patient with type IIa HM. Particularly, the use of the AFA seemed to induce a complete and balanced maxillary-mandibular growth and to be e ective in terms of improvement of chin symmetry, occlusal plane, and oral commissure levelling.
Management of the occlusal canting is usually required both in orthodontic camou age and presurgical orthodontic treatment of patients with HM: early orthopaedic intervention is focused on the di erential control of teeth eruption between the opposing arches and the prevention or correction of dentoalveolar adaptation to the asymmetry; by contrast, after growth, the levelling of occlusal plane might require xed appliances combined with the use of miniscrews [26][27][28].
Conceivably, the reported favourable result is related to the special conditions of the present case. In fact, the very early age, the excellent cooperation, and the timing of treatment may a ect the success of the treatment of asymmetric facial growth [29,30]. Early interceptive orthodontic treatment is frequently recommended both in children with craniofacial anomalies and in nonsyndromic patients for the positive e ect on skeletal growth and dental development [31][32][33][34]; moreover, in growing subjects, it may improve nasal function and prevent the development of respiratory disorders [35][36][37] and of muscle function disturbances [38]. e long-term stability of facial aesthetic is demonstrated by photography, which is the standard means of documenting facial appearance [39]. However, three-dimensional (3D) techniques should be considered the ideal tool for assessment of craniofacial morphology in patients with skeletal asymmetry: compared to conventional two-dimensional representation, 3D evaluation overcomes problems in head positioning and may be used to quantify hard/soft tissue de ciency, as well as to monitor and measure the e ects of both growth and treatment [40,41]. Particularly, objective measurements of the skeletal response can be performed on pre-and posttreatment 3D computerised tomography (CT), documenting incremental growth of the mandible. Given the mild form of the present case, we chose not to perform such exam during the follow-up. Interestingly, noninvasive methods, such as laser surface scanner, stereophotogrammetry, or ultrasonographic measurements, are being intensively investigated in order to make a quanti cation of facial topography without ionising radiation [42][43][44][45][46][47].
As for other craniofacial malformations, the role of orthodontists is very important in the interdisciplinary management of patients with HM, especially in cases with mild mandibular and soft tissue de ciencies [48][49][50][51][52]. Problems related to facial appearance may cause severe psychosocial disturbances [53]; thus, improvement of patient aesthetic appearance is also part of treatment objectives [54].
Proper orthopaedic intervention in the early age may induce an improvement of aesthetics, function, and psychological aspects, reducing or even eliminating the need for maxillary and mandibular osteotomies in late adolescence.

Conflicts of Interest
e authors declare that there are no con icts of interest regarding the publication of this paper.