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Three-dimensional surgical management of a patient with Pruzansky I hemifacial microsomia and severe facial asymmetry: A 4-year follow-up

Three-dimensional surgical management of a patient with Pruzansky I hemifacial microsomia and severe facial asymmetry: A 4-year follow-up



American Journal of Orthodontics and Dentofacial Orthopedics, 2022-05-01, Volume 161, Issue 5, Pages 708-726, Copyright © 2021 American Association of Orthodontists


Treatment of hemifacial microsomia is challenging and often requires multiple interventions to restore function and facial esthetics. In this article, the combined orthodontic-surgical treatment of a young patient exhibiting Pruzansky I hemifacial microsomia is reported. The patient was aged 15 years, but his bone age was determined to be 18 years. His facial asymmetry was severe, with the nose and a retrusive chin deviated to the left side and a canted smile. The presurgical phase was aimed at centering the mandibular midline to the center of the chin through the distal movement of the mandibular left buccal dentition. The surgery was planned with 3-dimensional computer-aided surgical simulation and included a LeFort I and unilateral sagittal split osteotomies combined with a genioplasty. This report illustrates the therapeutic stages and a 4-year follow-up of a unique and complex orthognathic surgical approach, chosen among other alternatives and leading to improved function and appearance and stable results.

Highlights

  • Hemifacial microsomia can be successfully treated with an orthodontic-surgical approach.

  • Unilateral sagittal split osteotomy can correct severe asymmetries with good stability.

  • Three-dimensional surgical planning facilitates and improves surgical results.

  • Anatomic features should dictate distalization modality in personalized treatment.

Hemifacial microsomia (HM) is the second most common congenital facial anomaly after cleft lip/palate and is characterized by unilateral aberrations of the components of the first and second branchial arches. Both hard (temporomandibular joint, mandibular ramus) and soft tissues (masticatory muscles and the ear) structures are often underdeveloped. Occasionally, defects of the second branchial arch involving the facial nerve and facial muscles coexist with HM. The affected ear often is lower than its normal counterpart and may have an external soft-tissue malformation. Auditory problems (conducive deafness) may result from underdevelopment of the osseous components of the auditory system and facial nerve dysfunction. The asymmetrical face is characterized by an off-centered chin and facial midline usually deviated to the affected side. Often, one commissure is situated at a higher level than the other, inducing an oblique lip line. Other asymmetric symptoms include the unilateral hypoplastic maxillary and temporal bones, unilateral shorter zygomatic arch. ,

Minor to moderate HM can be corrected with one surgical procedure, but it is usually beneficial to apply a staged approach when treating either functional or major structural asymmetries. Accordingly, if the condition involves both the craniofacial skeleton and the overlying soft tissues, the deeper structures are corrected first, and the superficial soft tissues are addressed at a later stage. Although 2-dimensional planning remains widely used in orthodontics and orthognathic surgery, computer-aided surgical simulation, and computer-aided orthognathic surgery are considered the gold standard in treating asymmetries. Numerous 3-dimensional (3D) virtual imaging and planning techniques combine information from facial soft tissue, skeleton, and dentition together. De Riu et al reported an average error of 1.98 mm for linear measures and 1.19° for angular measures after comparing virtual planning and actual outcomes. However, they advocated considering a margin of error for the correction of inaccuracies in virtual planning, primarily because of the difficulty in simulating the soft-tissue changes.

Mild mandibular asymmetries (<5 mm) were shown to be successfully corrected by unilateral sagittal split osteotomy (USSO) without causing adverse complications on the temporomandibular joint because of the adaptability of the mandibular condyle to small changes in its relation to the glenoid fossa. The affected side is operated by advancing or setting back the tooth-bearing segment, leaving the condyle on the affected side intact and rotating the opposite condyle within physiological limits. Inevitable anteroposterior changes at the incisors were recorded when rotating the midline and should be anticipated for the orthodontic presurgical planning. Stable results were reported 3 years after surgery. ,

This report presents a patient with severe facial asymmetry associated with HM, treated with a combination of orthodontics and orthognathic surgery that was planned through 3D simulation and included USSO.

Diagnosis and etiology

The patient aged 15 years 7 months presented to the Division of Orthodontics and Dentofacial Orthopedics at the American University of Beirut Medical Center with a chief complaint of facial asymmetry and crowding of the maxillary right lateral incisor. The patient did not report any history of trauma or prior orthodontic treatment. He was diagnosed with HM, classified as Pruzansky I, with mild hypoplasia of the condyle and ramus on the left side and a small ear. This craniofacial anomaly had caused a severe facial asymmetry that became more noticeable with growth. Limited mouth opening was observed with no pain.

On facial examination, severe asymmetry was noted with the nose and chin deviated to the left by almost 10 mm, in addition to canted lips and asymmetrical ears. Soft tissues were generally thinner on the left side with a grade 1 left microtia. On smiling, a severe cant of the maxilla was observed, resulting in increased dental and gingival (nearly 2 mm) display on the right side compared with the left side. Bilateral Class I occlusion was associated with increased overjet at the level of the maxillary right lateral incisor and an overbite of 20%. The mandibular midline coincided with the maxillary midline but was deviated 3 mm to the right of the center of the chin ( Figs 1 and 2 ). The pretreatment model showed an asymmetric maxillary arch form wider on the left side and flatter on the right side, likely compensating for the mandibular deviation.

Pretreatment facial and intraoral photographs.
Fig 1
Pretreatment facial and intraoral photographs.

Pretreatment dental casts.
Fig 2
Pretreatment dental casts.

The panoramic examination revealed the presence of all teeth. The third molars had not erupted, the mandibular assuming a mesioangular position. On the left side, the condyle appeared smaller, the ramus shorter, and the antigonial notch exaggerated compared with the contralateral right structures. The posteroanterior cephalometric radiograph disclosed a deviated septum, canted maxilla and mandible, and a deviated chin. The cephalometric analysis revealed a mild skeletal Class II relationship with an ANB angle of 4°, a convex subnasal profile, and a normodivergent vertical pattern. Double images of the mandibular corpus, ramus, and dentition were visible, expectedly resulting from the severe facial asymmetry ( Fig 3 ). The maxillary and mandibular incisors were proclined. The complete cephalometric analysis is shown in the Table . The patient’s bone age was 18 years, assessed on a hand-wrist radiograph using the Greulich and Pyle atlas ( Fig 3 , D ).

Pretreatment lateral and posteroanterior cephalometric, panoramic, and hand-wrist radiographs.
Fig 3
Pretreatment lateral and posteroanterior cephalometric, panoramic, and hand-wrist radiographs.

Table
Lateral cephalometric measurements
Measurement Norm Pretreatment Presurgical Posttreatment Postretention
SNA, ° 82.0 82.0 83.5 83.0 83.5
SNB, ° 80.0 78.0 79.0 82.0 82.5
ANB, ° 2.0 4.0 4.5 1.0 1.0
Wits appraisal, mm −1.0 −3.0 −3.0 −5.0 −6.0
LFH/TFH, % 50.0 53.0 53.0 54.0 54.0
SN-GoGn, ° 32.0 31.0 33.0 32.0 32.0
PP-H, ° 0.0 0.0 0.0 −2.0 −2.0
PP-GoGn, ° 25.0 25.5 27.5 28.0 28.0
U1-NA, ° 22.0 23.5 24.0 33.0 33.0
U1-NA, mm 4.0 3.0 3.0 7.0 7.0
U1-SN, ° 104.0 110.0 111.0 117.0 118.0
U1-PP, ° 110.0 116.0 117.0 121.0 121.0
L1-NB, ° 25.0 30.0 28.0 29.0 30.0
L1-NB, mm 4.0 6.0 6.0 6.0 6.0
L1-GoGn, ° 90.0 96.0 94.5 94.5 95.0
FMIA 64.0 53.5 57.5 57.0 57.0
U1-L1 131.0 122.0 122.5 116.5 116.0
Lower lip to E-Line, mm −2.0 0.0 0.0 −1.5 −1.5
Upper lip to E-Line, mm −4.0 −3.0 −3.0 −4.0 −4.0

Treatment objectives

The treatment objectives were to (1) align the nose and chin with the facial midline, (2) level the occlusal cant, (3) reduce the facial convexity and improve the chin point projection, and (4) preserve the Class I canine and molar occlusions and align the maxillary right lateral incisor. These objectives were pursued to improve the balance of hard and soft tissues of the middle and lower thirds of the face and enhance smile esthetics.

Treatment alternatives

Orthodontic treatment alone would not address the nasal and chin deviations, maxillary cant, and convex facial profile. Four surgical treatment alternatives were presented to the patient and his parents.

The first option included a LeFort I osteotomy to intrude the maxilla on the right side and extrude it on the left side, bilateral sagittal split osteotomy to advance and extrude the left side of the mandible, and genioplasty to advance the chin and move it to the right. In addition, both jaws would be rotated in a counterclockwise direction to improve the chin projection. No changes would be needed to the right ramus and mandibular body, normal in shape and size. Accordingly, a second option would limit the mandibular surgery to the left side through a USSO. This alternative would reduce the operation time and the incidence of per operative complications, including inferior alveolar nerve damage, as well as postoperative swelling and pain.

The third alternative was distraction osteogenesis (DO) of the mandibular left side, an established versatile technique capable of increasing the volume of the hard tissues and stimulating soft tissues histogenesis. The main advantage of DO is its possible application while the patient is still growing, thus minimizing functional problems and psychological trauma during growth. In some dysmorphologies, DO is not sufficient to achieve the desired esthetics, and a secondary procedure must be considered. Because the patient’s bone age is advanced relative to his chronological age and he nearly completed his growth, orthognathic surgery could be performed without delay and would result in more accurate positioning of the facial components, particularly when applying the 3D surgical planning technology.

The fourth option would include the use of temporary skeletal anchorage devices (TSADs) to correct the occlusal cant by intruding the maxillary right side and extruding the mandibular right side, combined with a genioplasty and rhinoplasty to center the chin and nose to the facial midline along with soft-tissue augmentation procedures on the left side to improve facial symmetry. However, soft-tissue grafting is associated with numerous complications such as donor site morbidity, resorption of graft, and infection. This option was not recommended because it would not address the origin of the asymmetry (mandibular left ramus and body) and the canted maxilla. After discussing these treatment options with the patient and his parents, the second surgical option was adopted.

Unlike typical asymmetries characterized by the lateral position of the mandibular dental midline in relation to the facial midline, this patient’s mandibular midline aligned with the facial and maxillary midlines; however, it was to the right of the center of the chin by around 3 mm if we follow the long axis of the mandibular central incisors ( Fig 4 ). Therefore, considering the significant amount of chin asymmetry (10 mm), the mandibular midline deviation would be corrected by the orthodontic movement followed by the sagittal and vertical movement of the mandibular sagittal split and genioplasty. At the end of the presurgical phase, the mandibular midline must be moved to the left. Consequently, the Class I canine and molar relations on the left side would be transformed into end-on Class II relations before regaining the Class I occlusion after surgery.

Extraoral photographs illustrating the chin asymmetry: A, the chin axis ( blue ) deviates to the left of the sagittal plane ( red ) and intersects the transverse genial axis ( white ) to the left of its center, revealing the extent of the genial asymmetry; B, the vertical line following the long axis of the central incisors ( yellow ) intersects the chin 3 mm to the right of its center ( black dot ).
Fig 4
Extraoral photographs illustrating the chin asymmetry: A, the chin axis ( blue ) deviates to the left of the sagittal plane ( red ) and intersects the transverse genial axis ( white ) to the left of its center, revealing the extent of the genial asymmetry; B, the vertical line following the long axis of the central incisors ( yellow ) intersects the chin 3 mm to the right of its center ( black dot ).

To shift the mandibular midline to the left side, 2 presurgical orthodontic treatment alternatives were available. The first consisted of distalizing the mandibular buccal teeth by the amount of the midline deviation after extracting the mandibular left third molar. The second option would involve the extraction of the mandibular left second premolar with moderate anchorage. However, because a counterclockwise rotation of the mandible would induce a more retroclined appearance of the mandibular incisors to the face, a minimal presurgical retraction of the mandibular incisors was indicated, favoring a nonextraction approach. Thus, the distalization option was preferred, which would also spare the loss of the mandibular left premolar, in addition to the third molar that had to be extracted before surgery. Moreover, this option would result in a Class I molar occlusion on the left side instead of a Class III molar relationship with the extraction option. The intended distalization movement aligns with the findings of Kim et al, who advocated that mandibular second molars distalization for >3 mm is not recommended because of the neighboring bony anatomy. Accordingly, surgical transverse movement of the chin would be justified to correct the remaining asymmetry in the chin and center it relative to the midsagittal plane ( Fig 4 , A ).

Treatment progress

The treatment was initiated with the placement of bands and preadjusted 0.022-in brackets with Roth prescription (Mini Twin; Ormco, Orange, Calif) on the maxillary and mandibular teeth. The archwire sequence progressed from 0.014-in nickel-titanium wire to 0.016 × 0.022-in stainless steel (SS) wire. The patient’s mandibular third molars were extracted during leveling. After alignment, a nickel-titanium open coil spring was placed between the mandibular left first and second molars to distalize the latter ( Fig 5 , A ). When the space between the left molars reached 3 mm, a 0.016-in archwire with stops mesial to the mandibular left second molar and mesial to the mandibular right first premolar was engaged to hold the left second molar in its distalized position. A TSAD (3M, Unitek, Monrovia, Calif) of 8 mm in length and 1.8 mm in diameter was inserted buccally between the mandibular molars to distalize the remaining mandibular left buccal teeth using an elastomeric chain extended from the TSAD to the mandibular left canine, with bite raising resin on maxillary second molars to avoid occlusal interference between maxillary canine and the mandibular canine bracket ( Figs 5 , B , C , and D ). Distalization of the second molar was limited to 3 mm because of its proximity to the lingual cortex, as demonstrated on the cone-beam computed tomography (CBCT) axial cut ( Fig 5 , E ). Seating elastics, hooked on maxillary and mandibular first premolars and canines, were worn to avoid labial crown tipping. Concurrently, sequential coordinated rectangular archwires were engaged in the maxillary arch reaching 0.021 × 0.025-in SS wire for the full expression of torque.

A, Distalization of the mandibular left second molar with an open coil spring. B, TSAD placed between the left molars. C and D, Distalization of the mandibular buccal teeth with spaces created mesial to left canine. E, Presurgical CBCT axial cut showing the roots of the mandibular left second molar in contact with the lingual cortex of the mandibular body.
Fig 5
A, Distalization of the mandibular left second molar with an open coil spring. B, TSAD placed between the left molars. C and D, Distalization of the mandibular buccal teeth with spaces created mesial to left canine. E, Presurgical CBCT axial cut showing the roots of the mandibular left second molar in contact with the lingual cortex of the mandibular body.

After distalizing the mandibular left buccal teeth, the mandibular incisors were retracted and shifted to the left side using an elastomeric chain stretched between the molars and helices bent distal to lateral incisors on 0.016-in SS archwire while holding the distance between right molar and helix with an SS ligature. After 18 months of presurgical orthodontic treatment, the patient was ready for surgery but decided to delay it until his summer vacation. Meanwhile, finishing mechanics were applied through the addition of mesiobuccal rotation bends on a 0.018-in SS archwire to the maxillary canines, later reproduced on the rectangular surgical archwire; root parallelism was achieved as indicated on a panoramic radiograph by rebonding the mandibular canine brackets ( Fig 6 ). Subsequently, the mandibular archwire was built up sequentially to 0.021 × 0.025-in SS to optimize torque expression, mainly on the mandibular left buccal teeth. The anterior hooks were placed between the maxillary and mandibular central incisors in the operation room before the surgery.

Presurgical facial and intraoral photographs. Patient smiling photograph with a tongue blade showing the frontal occlusal plane cant.
Fig 6
Presurgical facial and intraoral photographs. Patient smiling photograph with a tongue blade showing the frontal occlusal plane cant.

The virtual surgery was simulated in the Dolphin 3D software (Dolphin Imaging and Management Solutions, Chatsworth, Calif) using the presurgical full head CBCT, 3D facial photographs, and scanned study models ( Fig 7 ). To integrate soft tissues, hard tissues, and dental records, the scanned study models were first superimposed on the CBCT, and the facial photographs were later overlaid. The surgical planning started by establishing the position of the maxilla and mandible relative to an axial reference (midsagittal plane). This step revealed the mandibular asymmetry with shorter ramus and mandibular body on the left side. Using the midsagittal reference plane, the maxillary cant was corrected, and the mandibular left side was adjusted to mirror the right side by extruding the left side and moving it forward. Consequently, a computer-aided design and manufacturing intermediate surgical splint was fabricated ( Fig 8 ). In this perspective, a final splint was unnecessary because the surgical occlusion was solid and stable.

A, Presurgical panoramic. B, Lateral cephalometric radiographs. C, Lateral cephalometric radiograph tracing. D, Posteroanterior cephalometric radiographs. E, Three-dimensional reconstruction showing the midline discrepancy between the maxillary and mandibular dental midlines (traced following the long axes of the central incisors) and indicates their position relative to the corresponding jaw.
Fig 7
A, Presurgical panoramic. B, Lateral cephalometric radiographs. C, Lateral cephalometric radiograph tracing. D, Posteroanterior cephalometric radiographs. E, Three-dimensional reconstruction showing the midline discrepancy between the maxillary and mandibular dental midlines (traced following the long axes of the central incisors) and indicates their position relative to the corresponding jaw.

Surgical simulation using Dolphin 3D with the resulting computer-aided design and manufacturing intermediate surgical splint.
Fig 8
Surgical simulation using Dolphin 3D with the resulting computer-aided design and manufacturing intermediate surgical splint.

During surgery, a mandible-first sequence was implemented, starting with a USSO on the left side. The surgical cut followed the original Trauner and Obwegeser description with the distal cut directed posteriorly above the mandibular angle to advance the mandible by 4 mm and elongate it by 7 mm. Next, a 1-piece LeFort I osteotomy was performed to extrude the left side by 3.5 mm and intrude the right side by 1.5 mm. Finally, the chin was advanced by 3 mm and moved to the right by 4 mm. Both jaws were rotated counterclockwise to improve the chin projection ( Fig 9 ).

A, The original Obwegeser cut performed on the left side of the mandible. Note the preservation of the integrity of the mandibular border as the lower cut end above the mandibular angle. B, Planning of genioplasty showing the amount of movement required (4 mm).
Fig 9
A, The original Obwegeser cut performed on the left side of the mandible. Note the preservation of the integrity of the mandibular border as the lower cut end above the mandibular angle. B, Planning of genioplasty showing the amount of movement required (4 mm).

The postsurgical orthodontic phase was initiated 3 weeks postsurgery ( Fig 10 ). Maxillary and mandibular 0.016-in SS archwires were inserted, and the patient was instructed to wear seating elastics. Upon debonding of the fixed appliances, 2 fixed retainers were bonded lingually from canine to canine in both arches. In addition, a maxillary removable modified wrap-around retainer was given to the patient with instructions of full-time wear for the first 6 months. Final records were taken after appliance removal ( Figs 11-13 ). Treatment changes on superimposed cephalograms are shown in Figure 14 . The total treatment duration was 28 months but could have been shorter (2 years) had the patient not postponed the surgery for nearly 6 months.

Postsurgical facial photographs, lateral and posteroanterior cephalometric, and panoramic radiographs.
Fig 10
Postsurgical facial photographs, lateral and posteroanterior cephalometric, and panoramic radiographs.

Posttreatment facial and intraoral photographs.
Fig 11
Posttreatment facial and intraoral photographs.

Posttreatment lateral and posteroanterior cephalometric and panoramic radiographs.
Fig 12
Posttreatment lateral and posteroanterior cephalometric and panoramic radiographs.

Posttreatment dental casts.
Fig 13
Posttreatment dental casts.

A, Overall superimpositions of the pretreatment and posttreatment lateral cephalograms. B and C , Maxillary and mandibular regional superimposition of the pretreatment and posttreatment lateral cephalograms. D, Overall superimpositions of the pretreatment and posttreatment posteroanterior cephalograms ( black , pretreatment; red , posttreatment).
Fig 14
A, Overall superimpositions of the pretreatment and posttreatment lateral cephalograms. B and C , Maxillary and mandibular regional superimposition of the pretreatment and posttreatment lateral cephalograms. D, Overall superimpositions of the pretreatment and posttreatment posteroanterior cephalograms ( black , pretreatment; red , posttreatment).

Treatment results

The posttreatment records indicated that the treatment objectives were achieved. The extraoral photographs revealed a significant improvement in the patient’s facial symmetry, smile esthetics, and soft-tissue profile. Three-dimensional surgical preparation helped accurately plan the surgical movements leading to improved facial symmetry despite the absence of a bony gonial angle and the presence of thin soft tissues on the left side. Nevertheless, the nose remained slightly deviated to the left and the left ear smaller in size. Smile esthetics improved drastically in terms of smile symmetry, width, show of incisors, smile arc, and the corners of the mouth became symmetrically positioned on smile.

The lateral cephalometric analysis and the superimposition on the cranial base showed normalization of the sagittal relations between the jaws and the elimination of the double images of the mandibular borders. Moreover, the measurements disclosed improvement of the ANB angle (from 4° to 1°) and the SNB angle (by 4°) ( Table ). In addition, the cephalometric superimpositions on the cranial base show 5° counterclockwise rotation of the jaws that helped improve the chin projection. The mandibular superimposition reveals 3 mm of distal movement achieved at the first molar level along with the vertical displacement of the mandible caused by its downward movement on the left side. The posteroanterior cephalometric radiograph superimpositions showed significant improvement in the skeletal symmetry, including the occlusal plane inclination, but the left gonial angle remained fuller on the right side compared with the left side ( Figs 11 and 14 , D ). In addition, this posteroanterior superimposition indicated that the lingual tipping of the mandibular left buccal teeth, which was partially corrected in the presurgical orthodontic phase, was completed through the surgical roll of the jaws and the postsurgical orthodontic seating with interarch elastics ( Fig 14 , D ). Root parallelism was properly achieved, and no signs of root resorption or bone loss were evident on the posttreatment panoramic radiograph.

Intraorally, the dental midlines coincided with each other and to the facial midline. Optimal dental alignment, overbite, and overjet were achieved. Class I relationship was maintained with proper interdigitation on both sides. At debonding, the patient had no masticatory disturbances despite the residual limitation in mouth opening and mandibular shift to the right. His oral function returned close to normal after he was given exercises to strengthen the left side muscles ( Fig 15 ).

Facial photographs showing deviation on mouth opening: A, at debonding; B, 2 months after debonding; C, 4 years posttreatment.
Fig 15
Facial photographs showing deviation on mouth opening: A, at debonding; B, 2 months after debonding; C, 4 years posttreatment.

At 4-year postretention, extraoral and intraoral results were stable with further increase in mouth opening and reduction of mandibular shift ( Figs 16 and 17 ). A midline deviation of 1 mm was noticed with increased abrasion of the edges of the maxillary central incisors. Superimpositions of the posttreatment and 4-year follow-up lateral cephalograms showed stability of the jaws’ position, remodeling of the gonial angle, and little residual growth.

Facial and intraoral photographs after 4 years of retention.
Fig 16
Facial and intraoral photographs after 4 years of retention.

Dental casts after 4 years of retention.
Fig 17
Dental casts after 4 years of retention.

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