Treacher Collins syndrome: Orthodontic treatment with mandibular distraction osteogenesis and orthognathic surgery

Interdisciplinary treatment for patients with Treacher Collins syndrome is challenging because of the rarity of the condition and the wide variety of phenotypic expression. A 23-year-old male was diagnosed with Treacher Collins syndrome with a history of severe obstructive sleep apnea. He presented with a Pruzansky-Kaban classification grade I mandible, skeletal type II pattern with a hyperdivergent mandibular plane, severe convex profile, and Class II malocclusion with a missing mandibular incisor. Improvement of facial esthetics was achieved by a combination of orthodontics, mandibular distraction osteogenesis, and 2-jaw maxillomandibular advancement surgery. Presurgical orthodontic treatment involved permanent tooth extraction to relieve severe crowding, and Class III mechanics were employed to increase overjet. Correction of mandibular hypoplasia by increasing ramal height and the mandibular length was done by intraoral mandibular distraction osteogenesis. Counterclockwise rotation of the mandibular plane angle and a Class III occlusion with negative overjet were achieved after mandibular distraction osteogenesis. A postdistraction posterior open bite was maintained with a biteplane during the consolidation period. Subsequently, 2-jaw orthognathic surgery was performed. LeFort I osteotomy was done for maxillary advancement to correct an anterior crossbite, eliminate canting, and reestablish occlusal contact at the mandibular occlusal plane. Bilateral sagittal split ramus osteotomy was done to correct the residual mandibular deviation. A genioplasty was also performed to improve chin projection. Postoperatively, the oropharyngeal airway was enlarged. The patient’s facial profile and obstructive sleep apnea problem were improved as a result of advancement and counterclockwise rotation of the maxillomandibular complex.


  • Interdisciplinary care for an adult with Treacher Collins syndrome and sleep apnea is presented.

  • Multidisciplinary treatment included orthodontics and 2-stage surgery with genioplasty.

  • Facial appearance and obstructive sleep apnea were improved posttreatment.

Treacher Collins syndrome (TCS; OMIM154500), also known as mandibulofacial dysostosis or Franschetti-Zwahlen-Klein syndrome, is a rare autosomal-dominant craniofacial deformity , The etiology of this syndrome was due to abnormal development of the first and second branchial arches. The incidence of TCS varies between 1 in 35,000 and 1 in 50,000 live births. , Mutations in the TCOF1 gene are the main etiology, whereas smaller subsets of TCS are caused by mutations in the POLR1D and POLR1C genes. ,

The spectrum of craniofacial deformities in TCS involves the periorbital region, bilateral hypoplasia of the zygoma, maxilla, mandible, and associated soft tissues. According to Tessier’s classification of craniofacial clefts, this syndrome may present with clefts no. 6 (maxillozygomatic cleft), no. 7 (temporozygomatic cleft and hypoplasia of mandibular ramus), or no. 8 (frontozygomatic cleft). Cleft palate may also be found in some patients with TCS. Bone and soft tissue anomalies also result in the impairment of several important functions.

The facial features of TCS patients typically present as down-slanting palpebral fissures, coloboma of the lower eyelid between the middle and lateral thirds, total or partial absence of lower eyelashes, vertical sclerodermic furrow on the cheek, microtia or atresia of the external ears, skin tags, and hypoplasia or absence of the temporal muscle.

The deformities of the skeletal and soft tissues lead to the impairment of several functions such as upper airway obstruction, feeding difficulties, hearing loss because of atresia of the external auditory canal, speech problems secondary to hearing loss, visual disturbances because of upper eyelid ptosis or lower lid coloboma, and lip incompetence as the result of macrostomia, impaired levator muscle function of the upper lip. , , , ,

The maxillomandibular hypoplasia, together with the associated glossoptosis in TCS, may predispose the patient to pharyngeal airway obstruction and obstructive sleep apnea (OSA). , Plomp et al reported the prevalence of OSA in adult TCS patients to be 41%. TCS with severe airway obstruction may require tracheostomy and, in some patients, may be the cause of perinatal death. , ,

Dentoskeletal characteristics in TCS commonly present as hypoplasia of the zygoma, maxilla, mandible, a skeletal open bite, reduced posterior facial height, increased gonial angle, antegonial notching, and posterior rotation of the occlusal plane. The facial soft tissues show a severe convex facial profile, short chin-throat length, recessive chin, and lip incompetence. Intraorally, an anterior open bite malocclusion may be seen. , , ,

The management of TCS by conventional surgical techniques was published by Tessier and Tulasne, in which a maxillomandibular surgical procedure was done in 2 stages. In the first stage, mandibular surgery was performed to lengthen the ramus and advance the mandible by a V-shaped osteotomy with bone graft augmentation. The second stage involved either a LeFort I maxillectomy or LeFort II to III levels. The midfacial rotation was carried out by lowering the posterior part of the maxilla to open the choanae. However, this treatment method is a highly challenging procedure with unsatisfactory results.

In recent years, distraction osteogenesis has become the treatment of choice to manage airway obstruction in patients with congenital deformities such as TCS and other syndromes with micrognathia. , In this procedure, the mandible is gradually advanced, allowing the tongue base to adapt to a more forward position, away from the oropharynx.

Regarding orthodontic treatment, a few treatment modalities have been proposed for teenagers with TCS. Although camouflage orthodontic treatment is feasible to correct the dental malocclusion, such as that reported by Okada and Kuroda, most patients with TCS require orthognathic surgery to correct the severe facial deformity. A combined orthodontic and orthopedic approach with 2-jaw surgery has been described by Chung et al and Opitz et al. Presurgical orthodontic treatment could be carried out to correct any maxillary transverse discrepancies, either by using a rapid maxillary expansion in growing patients or surgically-assisted rapid palatal expansion in adults. Extraction of permanent teeth may be necessary to manage tooth size-arch length discrepancies. Because of the complexity of TCS, it is important for orthodontists to be up-to-date with the interdisciplinary management of the syndrome.

To date, there have been only a few papers published regarding the orthodontic management of TCS. The purpose of this report is to present the combined orthodontic-surgical treatment of an adult TCS patient with OSA.

Diagnosis and etiology

A 23-year old male was presented to our orthodontic clinic with a chief complaint of his abnormal face. His body mass index was 17.8, which indicated an underweight body. The patient’s Epworth Sleepiness Scale showed a score of 10, which suggested possible sleep apnea.

According to the patient’s ear, nose, and throat (ENT) examination report, he was diagnosed with TCS and severe OSA. Polysomnography demonstrated an apnea index of 4.6, hypopnea index of 45.0, apnea-hypopnea index (AHI) of 49.6, respiratory disturbance index of 54.2, and the lowest desaturation of 94.0% ( Table ). When continuous positive airway pressure (CPAP) was applied at 9 cm H 2 O, the parameters showed improvement (apnea index of 2.8, hypopnea index of 17.0, AHI of 19.8, respiratory disturbance index of 19.8, and lowest desaturation of 96%). Unfortunately, his compliance in using CPAP was poor.

Lateral and posteroanterior cephalometric analysis and respiratory parameters
Measurement Ethnic norm SD Pretreatment Post-MDO Posttreatment
Skeletal A-P
SNA (°) 83.9 3.3 78.0 78.0 83.0
SNB (°) 80.9 3.1 70.0 77.0 78.0
ANB (°) 3.0 1.6 8.0 1.0 5.0
Wits appraisal (mm) −1.9 2.9 1.5 −8.1 −2.0
Skeletal vertical
FH-OP (°) 9.0 4.4 19.0 16.0 15.0
Mp-SN (°) 30.3 4.5 48.0 40.0 42.0
SN-PP (°) 8.0 3.4 9.0 9.0 7.0
PP-MP (°) 22.6 3.9 39.0 31.0 35.0
PFH/AFH (S-Go/N-Me) (%) 66.3 3.7 58.3 63.1 59.3
Co-Go (mm) NA NA 45.4 58.5 54.7
Go-Pg (mm) NA NA 60.1 66.2 70.6
Me point deviation (mm) 2.3 (left) 6.4 (right) 0
Dental relationship
SN-U1 (°) 105.8 5.6 102.0 99.5 101.0
U1-NA (mm) 4.6 2.1 4.9 4.0 2.5
Interincisal angle (U1-L1) (°) 127.0 7.7 108.0 130.0 126.0
L1-Mp (°) 96.2 6.1 105.5 88.2 90.8
L1-NB (mm) 6.0 1.9 12.2 10.4 7.3
Soft tissue profile
Chin-throat length (mm) 42.0 6.0 10.2 25.3 30.6
Chin-throat angle (°) 110.0 8.0 165.0 132.0 105.5
Holdaway angle (NB to H-line) (°) 14.0 3.8 28.6 15.3 16.7
Upper lip-E plane (mm) −1.0 2.0 5.2 0 1.3
Lower lip-E plane (mm) 2.0 2.0 6.6 6.2 0.5
Respiratory parameters
AHI <5/h 49.6 NA 3.2
AI 4.6 NA 1.9
HI 45.0 NA 1.3

SD, standard deviation; NA, no data available; AI, Apnea Index; HI, Hypopnea Index.

Ethnic normal values for Thais.

Furthermore, the patient was diagnosed with bilaterally moderate conductive hearing loss. He had undergone myringoplasty grafting at the university hospital and had been prescribed hearing aids. An abnormal electrocardiogram was also detected.

The patient was presented with down-slanting palpebral fissures, mild hypertelorism, lower eyelid coloboma, partial absence of left lower eyelashes, apparent large beak-like nose, and deficient malar area. Because of a severely retrognathic mandible, he showed the typical facial features of TCS with a convex facial profile, short throat length of 10 mm (normal, 42 ± 6 mm), and lip-chin-throat angle of 128° (normal, 110° ± 8°) ( Fig 1 ).

Fig 1
Pretreatment extraoral and intraoral photographs.

A compensated dentition characteristic of Class II skeletal pattern was observed in this patient, which included retroclined and retruded maxillary incisors with proclined and protruded mandibular incisors. Severe crowding was seen in the maxillary anterior region. The molar and canine relationships were Class II end-on on both sides. The anterior teeth showed an overjet of 4 mm and an overbite of 0 mm. The maxillary and mandibular dental midlines were deviated to the right by 1 mm and 2 mm in relation to the facial midline, respectively. The maxillary right canine was completely blocked-out labially. The mandibular right lateral incisor was congenitally missing ( Fig 2 ). On functional examination, the patient had a limited protrusive movement without other symptoms of temporomandibular joint disorder.

Fig 2
Pretreatment digital models.

The panoramic radiograph revealed bilateral hypoplastic condyles and mandible, which can be identified as grade I of the Pruzansky-Kaban classification. The posteroanterior and lateral cephalometric radiographs are shown in Figure 3 .

Jun 12, 2021 | Posted by in Orthodontics | Comments Off on Treacher Collins syndrome: Orthodontic treatment with mandibular distraction osteogenesis and orthognathic surgery

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