Maxillary and Mandibular Displacement in Hemifacial Microsomia: A Longitudinal Roentgen Stereometric Study of 21 Patients with the Aid of Metallic Implants

Congenital and acquired mandibular asymmetry: Mapping growth and remodeling in 3 dimensions

INTRODUCTION

Disordered craniofacial development frequently results in definitive facial asymmetries that can significantly impact a person's social and functional well-being. The mandible plays a prominent role in defining facial symmetry and, as an active region of growth, commonly acquires asymmetric features. Additionally, syndromic mandibular asymmetry characterizes craniofacial microsomia (CFM), the second most prevalent congenital craniofacial anomaly (1:3000 to 1:5000 live births) after cleft lip and palate. We hypothesized that asymmetric rates of mandibular growth occur in the context of syndromic and acquired facial asymmetries.

METHODS

To test this hypothesis, a spherical harmonic-based shape correspondence algorithm was applied to quantify and characterize asymmetries in mandibular growth and remodeling in 3 groups during adolescence. Longitudinal time points were automatically registered, and regions of the condyle and posterior ramus were selected for growth quantification. The first group (n = 9) had a diagnosis of CFM, limited to Pruzansky-Kaban type I or IIA mandibular deformities. The second group (n = 10) consisted of subjects with asymmetric, nonsyndromic dentofacial asymmetry requiring surgical intervention. A control group (n = 10) of symmetric patients was selected for comparison. A linear mixed model was used for the statistical comparison of growth asymmetry between the groups.

RESULTS

Initial mandibular shape and symmetry displayed distinct signatures in the 3 groups (P <0.001), with the greatest asymmetries in the condyle and ramus. Similarly, mandibular growth had unique patterns in the groups. The dentofacial asymmetry group was characterized by significant asymmetry in condylar and posterior ramal remodeling with growth (P <0.001). The CFM group was characterized by asymmetric growth of the posterior ramus (P <0.001) but relatively symmetric growth of the condyles (P = 0.47).

CONCLUSIONS

Forms of CFM are characterized by active and variable growth of the dysplastic side, which has a distinct pattern from other disorders of mandibular growth.

Three-dimensional longitudinal changes in craniofacial growth in untreated hemifacial microsomia patients with cone-beam computed tomography

INTRODUCTION

The purpose of this study was to evaluate the concept that the affected and contralateral sides do not grow at the same rate in patients with hemifacial microsomia. Changes in the cranial base, maxilla, mandible, and occlusal plane were evaluated on 3-dimensional images from cone-beam computed tomography data in untreated patients.

METHODS

Six patients were classified as having mandibular Pruzansky/Kaban type I, IIA, or IIB hemifacial microsomia. Cone-beam computed tomography (MercuRay; Hitachi, Tokyo, Japan) scans were taken before orthodontic treatment during both growth and postpuberty periods.

RESULTS

The cranial base as defined by the position of the mastoid process was in a different position between the affected and contralateral control sides. The nasomaxillary length or height was shorter on the affected side for all 6 patients with hemifacial microsomia regardless of its severity, and it grew less than on the contralateral control side in 5 of the 6 patients. The occlusal plane angle became more inclined in 4 of the 6 patients. The mandibular ramus was shorter on the affected side in all patients and grew less on the affected side in 5 of the 6 patients. The mandibular body grew slower, the same, or faster than on the control side.

CONCLUSIONS

The cranial base, position of the condyle, lengths of the condyle and ramus, and positions of the gonial angle and condyle can vary between the affected and contralateral control sides of patients with hemifacial microsomia, with the ramus and nasomaxillary length usually growing slower than they grow on the control side. These results suggest that many factors affect the growth rate of the craniofacial region and, specifically, the mandible in patients with hemifacial microsomia.

Orthognathic surgery for secondary cleft and craniofacial deformities

Orthognathic surgery is a critical component of surgical management of craniofacial deformities such as cleft lip and palate, craniofacial dysostoses, and mandibulofacial dysostoses. These operations can correct discrepancy in jaw relationship and malocclusion, relieve airway obstruction, correct facial asymmetry, optimize facial aesthetics, improve speech articulation, improve ability to masticate, and enhance psychological development and social interaction. Oral and maxillofacial surgeons who treat these deformities should be part of a craniofacial team to provide interdisciplinary care for patients. Distraction osteogenesis is a useful technique in the management of severe craniofacial deformities but does not replace conventional orthognathic surgery, which is safe and predictable. Recent advances in three-dimensional imaging and planning tools have made it possible to plan surgery more accurately and predictably.

Mandibular widening in hemifacial microsomia: a roentgen stereometric study of 11 patients with the aid of metallic implants

INTRODUCTION

Our objective was to study mandibular widening in untreated subjects with hemifacial microsomia.

METHODS

From the 3-dimensional files at the Department of Plastic and Reconstructive Surgery, Skane University Hospital in Malmö, Sweden, data of 11 subjects (3 girls, 8 boys) with hemifacial microsomia were retrieved. Their age range was 9 years 2 months to 13 years 2 months at the first examination. The mean observation period was 5 years 2 months. Each subject was studied by roentgen stereophotogrammetry with the aid of metallic implants.

RESULTS

A significant widening of the mandible was found, with a mean total change of 0.31 mm (range, 0.08-0.79 mm) and a mean annual change of 0.07 mm (range, 0.03-0.12 mm). In 2 subjects, narrowing of the mandible was found: -0.16 and - 0.23 mm.

CONCLUSIONS

The mandible got wider during adolescence in 9 of our subjects with hemifacial microsomia but to a lesser extent than has been reported in subjects without hemifacial microsomia and from ordinary orthodontic clinics. Sex difference was not addressed. It was suggested that chewing (forces and patterns) was responsible for the mandibular widening in our subjects; this is in line with previous research.

Ten-year follow-up of a patient with hemifacial microsomia treated with distraction osteogenesis and orthodontics: an implant analysis

INTRODUCTION

Distraction osteogenesis (DO) has become an accepted treatment method for patients requiring mandibular lengthening because of congenital malformations. However, the skeletal growth pattern of a distracted mandible in the long term has still not been clearly shown in the literature. The purpose of this report was to analyze the dentofacial changes observed during a 10-year follow-up period in a patient treated with mandibular DO.

METHODS

The patient was a 12-year-old girl with hemifacial microsomia who had undergone DO with an external device. Morphologic changes during the observation period were evaluated on panoramic radiographs and posteroanterior and lateral cephalograms. Six Björk-type titanium implants were placed bilaterally in the mandible under local anesthesia to analyze the mandibular skeletal changes over time.

RESULTS

Marked lengthening was achieved during the active phase of mandibular distraction. The ratio between the ramus heights of the affected and normal sides improved significantly in the affected side's favor as the mandible was lengthened, but this ratio returned to its initial value after 10 years.

CONCLUSIONS

Although there was some growth on the affected side during the follow-up period, it was not enough to catch up with the growth on the normal side. The original asymmetry recurred as a consequence of the growth pattern in this patient with hemifacial microsomia.