Causes and distribution of facial fractures in a group of South African children and the value of computed tomography in their assessment

The cases of 107 paediatric patients aged 0-12 years were retrospectively reviewed. The patients presented with facial trauma and both plain radiographs and computed tomography (CT) scans had been ordered. Sixty-five per cent of facial fractures were missed in radiography, but revealed on CT; fractures of the maxilla, the zygoma and the orbit were most frequently missed in radiography. Pedestrian motor vehicle accidents were the most frequent cause of facial fractures (37%), followed by passenger motor vehicle accidents (22%). In contrast with other studies reporting the mandible as the most frequent facial fracture site, the most common fracture sites in this study, in descending order of frequency, were the orbit, the frontal bone and the maxilla.

Zygomatic Implants—Protocol for Immediate Occlusal Loading: A Preliminary Report

PURPOSE

To investigate the modified protocol for immediate occlusal loading of the zygomatic implants and to report the preliminary results of this modified protocol.

MATERIALS AND METHODS

Four male patients and 1 female patient with edentulous maxillae were consecutively treated with the zygomatic implants under general anesthesia. All 5 patients were examined by computed tomography and investigated by the SimPlant software (Materialise NV, Leuven, Belgium). Based on the virtual surgical plans, mucosa-supported surgical guides were manufactured by rapid prototyping technique before implant operation. Instead of making a Le Fort I Osteotomy incision or a crestal incision, buccal vestibular incision was used to expose the surgical site for the zygomatic implant osteotomy and placement. Three patients had their remaining upper teeth removed on the same day as implant placement. One patient had undergone simultaneous placement of upper and lower implants followed by immediate loading. The immediate loading protocol was a 2-stage method using a customized provisional fixed prosthesis.

RESULTS

Ten zygomatic implants and 20 normal implants were installed in these 5 patients. These 5 patients were reviewed regularly for 6 to 10 months after immediate loading. The zygomatic implants were considered to be successful when they were asymptomatic with no clinical mobility and no sign of infection. All the zygomatic implants and normal implants were investigated individually after removing the provisional prosthesis and were found to be clinically stable and asymptomatic.

CONCLUSION

According to our observation, immediate occlusal loading of the zygomatic implants has a very good potential for success, as much as immediate occlusal loading of normal dental implants. The surgical placement of the zygomatic implant is simplified and facilitated by making use of the computer-assisted planning and the rapid-prototyping surgical guides.

The value of three-dimensional computed tomography in diagnosis and management of Jacob's disease

This study reports a case of Jacob's disease characterized with limited mouth opening due to bilateral coronoid hyperplasia forming pseudojoints with zygomatic arches. Magnetic resonance (MR) examination of temporomandibular joint (TMJ) is usually the imaging method chosen in patients with such symptoms. However, the coronoid processes can not be displayed because they are not included in field of view in MR imaging of TMJ. For that reason, these patients may be treated for a misdiagnosis of TMJ disorders. In this study, the aetiology and diagnostic methods of Jacob's disease, the pre-operative/post-operative role of three-dimensional computed tomography and some measurements used in diagnosis were evaluated.

[Examination of incident angle for photography of axial projection of zygomatic arch]

In axial zygomatic arch roentgenography, the radiographic angle is determined by taking account of the light field-projected image. However, this method is technically difficult and has poor reproducibility because the body target surface is uncertain at the time of positioning. Therefore, we obtained 3D-CT images from CT examinations of the facial or paranasal sinus, and we assessed the X-ray beam angle where the zygomatic arch is most clearly delineated in terms of sex and age by taking the acanthion-meatal line (France horizon) as the reference. The zygomatic arch was most clearly seen when the X-ray beam angle was perpendicular to the acanthion-meatal line. Excellent images were obtained, and reproducibility of the images was improved using the radiographic technique based on this result.

[The installation of zygomatic implants and drilling guide]

OBJECTIVE

To discuss the technique of installation of zygomatic implants in severely resorbed edentulous maxillae, and maxillary defect.

METHODS

Five patients received 8 zygoma implants and 11 dental implants. On the basis of an axial spiral CT data, anatomical models of natural size were manufactured using CAD/CAM system and before operation preoperative measurements of relevant parameters (length, areas, and volumes) carried out. Theses maxillary and zygomatic measurements obtained were referred for installing zygomatic implants.

RESULTS

The ideal direction and position of installation of the 8 zygomatic fixtures were obtained in 5 patients. The anatomical model and surgical plate were used for preoperative planning and intraoperative control of the insertion of zygomatic fixtures. The implants could be positioned precisely as preoperatively planned. The length of the zygomatic implants was between 40 mm and 50 mm.

CONCLUSIONS

The use of surgical drilling guides should be encouraged for zygomatic implant placement. 3-D image data and anatomical models improves preoperative planning and facilitates clinical procedure.

Point-to-Point Computer-Assisted Navigation for Precise Transfer of Planned Zygoma Osteotomies from the Stereolithographic Model into Reality

PURPOSE

To evaluate the feasibility and accuracy of a new method for planning and realizing zygomatic osteotomies in cases of established post-traumatic deformities using stereolithographic (SL) models and computer assisted navigation.

PATIENTS AND METHODS

In 5 patients, osteotomy and repositioning of the zygomatic complex was planned using SL models. The desired position of the zygoma in the patient was determined by fixing individualized osteosynthesis plates to predefined screw positions. The SL model and the patient were registered to the same 3-dimensional computed tomography data set via an occlusal reference frame on the patient and corresponding reference markers on the model. Prebent osteosynthesis plates from the surgical simulation on the model were fixed to corresponding screw positions on the patient, which were located by computer-assisted navigation. Evaluation of accuracy was performed by image fusion of postoperative computed tomography scans of the model and the patient.

RESULTS

Clinical outcome was satisfactory in all cases. The evaluation by image fusion showed alignment of the patient's and the model's zygoma in 4 of 5 cases. Mean measured distance between screw positions in the models and the patients were 1.1 +/- 0.3 mm for 44 screws. In 1 patient the treatment plan was changed intraoperatively because of unforeseen soft tissue limitations.

CONCLUSION

Point-to-point navigation is an accurate method to transfer the planning of a complex osteotomy from the SL model to the actual surgical procedure. Surgery is facilitated considerably because repositioning and osteosynthesis are achieved in 1 step.

Radiation-induced craniofacial bone growth inhibition: efficacy of cytoprotection following a fractionated dose regimen

BACKGROUND

Severe craniofacial growth disturbances are noted in 66 to 100 percent of children with head and neck cancers who received radiotherapy during their growing years. The authors have previously demonstrated the prevention of radiation-induced craniofacial bone growth inhibition following single-dose orthovoltage radiation to the orbitozygomatic complex in an infant rabbit model through the administration of the cytoprotective agent amifostine (WR-2721) before radiation treatment. The purpose of this study was to investigate the efficacy of cytoprotection using a fractionated dose regimen that better approximates the clinical application of radiation therapy.

METHODS

Thirty 7-week-old male New Zealand rabbits were randomized into three groups (n = 10), each receiving six fractions of orthovoltage radiation to the right orbitozygomatic complex: group C, sham irradiation control; group F35, total dose of 35 Gy; and group F35A, total dose of 35 Gy with administration of amifostine 200 mg/kg intravenously 20 minutes before each fraction. Bone growth was evaluated up to skeletal maturity (age 21 weeks) with serial radiographs and computed tomography scans for cephalometric analysis, bone volume, and bone density measurements.

RESULTS

Fractionated radiation resulted in significant (p < 0.05) bone growth inhibition compared with sham radiation in 16 of 21 cephalometric parameters measured and significantly (p < 0.05) reduced bone volume of the rabbit orbitozygomatic complex. Pretreatment with amifostine before each radiation fraction prevented growth deformities in four cephalometric parameters and significantly (p < 0.05) attenuated these effects in another seven parameters compared with radiated animals. Bone volumes were also significantly (p < 0.05) improved in F35A animals compared with F35 animals.

CONCLUSIONS

This study establishes that fractionation of orthovoltage radiation does not prevent the development of growth disturbances of the rabbit craniofacial skeleton and also demonstrates that preirradiation administration of amifostine is highly effective in the prevention and attenuation of radiation-induced craniofacial bone growth inhibition.

[Aneurysmal bone cyst of the maxilla. Report of one case]

Aneurysmal bone cysts are benign fibro osseous lesions, rarely present in maxillary region. We report the CT and morphological findings of aneurysmal bone cyst of the maxilla in a 15 years old female. The patient was subjected to a maxillectomy, preserving the orbit floor. The postoperative evolution has been uneventful. The tumor mainly involved the maxillary sinus with extension to the orbit wall and osseous palate. Very few cases of aneurysmal bone cysts of the maxilla have been reported in the literature.

The role of intraoperative ultrasonography in zygomatic complex fracture repair

Intraoperative assessment of the zygomatic arch is very important in achieving adequate repositioning. The correct alignment of the zygomatic arch indicates the proper position of the zygomatic bone and ensures adequate prominence of the lateral midfacial aspect. The aim of this study was to estimate the value of ultrasonography as an intraoperative repositioning control. In a clinical study of 25 patients, ultrasonography was employed for intraoperative visualization of the zygomatic arch before and after fracture repositioning. Twelve patients presented with isolated zygomatic arch fractures and 13 with combined fractures of the zygomatic bone and arch. The ultrasonographic findings were compared to the radiological and clinical findings. Ultrasonography was able to detect all fractures and dislocations of the zygomatic arch. It was possible to assess the repositioning in 24 out of 25 cases using ultrasonography. The ultrasound images were concordant with the radiographs. Clinical assessment by palpation only succeeded in isolated zygomatic arch fractures with an m-shaped impression, whereas it remained uncertain in nearly all cases with a different dislocation pattern. Ultrasonography was rapid and easy to perform, and is recommended as an intraoperative visualizing tool in all midfacial fractures with displacement of the zygomatic arch.

Primary tuberculous osteomyelitis of zygoma

Osteomyelitis of zygomatic bone is rare, and tuberculous osteomyelitis is even rarer. This is the case report of a 3-year-old child presenting with a discharging sinus and swelling on the zygoma, which was initially thought to be orbital cellulitis. After further examination, she was diagnosed as having tuberculosis of zygoma and responded to anti-tubercular chemotherapy.

[Position and orientation of zygomatic-area implant of zygo-buccal flange osseointegrated implant obturator]

OBJECTIVE

To provide objective data for position and orientation of zygomatic-area implant used in zygo-buccal flange osseointegrated implant obturator for patients with large maxillary defect.

METHODS

Fifty cases of normal unilateral zygomatic body with dentition were measured on three-dimensional spiral CT images. Measurements included the slope angle of zygomatic body on sagittal sectional image, the maximal horizontal distance from the buccal boundary of maxillary alveolar to outboard of maxillary sinus. Furthermore, the configuration of zygomatic body was observed on coronal sectional image.

RESULTS

The average rearward slope angle of zygomatic-body was 80.03 degrees. Forty-eight cases showed straight zygomatic-body configurations and two cases quite curvy. The maximal horizontal distance from the buccal boundary of maxillary alveolar to outboard of maxillary sinus was 6.77 mm.

CONCLUSIONS

In a normal condition, implants can be upright inserted tilting about 10 degrees ahead to utilize much zygomatic bone-volume in high site. In order to improve security and validity of implantation, it is better to take spiral CT examination to evaluate the bone volume and shape of zygomatic body before zygomatic-area implant.

Internal structure of zygomatic bone related to zygomatic fixture

PURPOSE

The purposes of this study were to investigate the internal structure of the edentulous zygomatic bone, which provides anchorage for the zygomatic fixture, using micro-computed tomography, and to examine the relation between the internal structure of the edentulous zygomatic bone and the zygomaticus fixture.

MATERIALS AND METHODS

Twenty-eight zygomatic bones of edentulous maxillae from cadavers were used. The mean age of cadaver specimens was 79.6 years. The specimens were analyzed using micro-computed tomography.

RESULTS

The internal structure of edentulous maxillae had thicker trabeculae in the region at the tip of the zygomaticus fixture than in other regions.

CONCLUSIONS

The present findings suggest that the presence of wider and thicker trabeculae at the end of the fixture promotes initial fixation. Also, when the trabeculae are able to support occlusal force after successful osseointegration, this thickening greatly aids the support of the fixture at the tip of the fixture, where stress is thought to be concentrated. In addition, the occlusal force was applied to the entire zygomatic bone. This preliminary study suggests that better understanding of the internal structure of the zygomatic bone will provide further information about the direction of installation of the zygomatic fixture, the ideal position of the zygomatic fixture, and the prognosis of implant therapy.

Cavernous hemangioma of the bony orbit

PURPOSE

To study the clinical features, diagnosis and management of intraosseous cavernous hemangioma of the orbit.

METHODS

Five cases of intraosseous cavernous hemangioma seen in our hospital from Jan 1, 1986 to Dec 31, 2000 were reviewed.

RESULTS

Among all five cases, two were male and three were female. The mean age was 47.6 years old, ranging from 39.0 to 55.0 years. The left orbit was affected in 4 cases and the right one in 1 case. The bony involvement occurred in frontal bone (two cases), zygomatic bone (two cases) and sphenoid bone (one case). A painless, slowly enlarging hard bony mass fixed to the bone with no pulsations was the main clinical sign. The x-ray and CT appearance of intraosseous cavernous hemangioma of the orbit were characteristic and usually diagnostic. The differential diagnosis of it included fibrous dysplasia, eosinophilic granuloma, multiple myeloma and metastatic carcinoma. Treatment is local removal of the bone containing the tumor.

CONCLUSIONS

Intraosseous cavernous hemangioma is a rare tumor of the orbit and usually has good surgical result.

Comparative data on facial morphology and muscle thickness using ultrasonography

The purpose of this investigation was to measure the thickness of the masseter, levator labii superioris, and zygomaticus major muscles; to examine the reproducibility of ultrasonographically measured muscle thickness; to evaluate the association between facial and masticatory muscle thickness and vertical facial pattern; and to test whether the variation in muscle thickness is related to the variation in the body mass index (BMI) of different individuals. The thickness of the masseter, levator labii superioris and zygomaticus major muscles was measured bilaterally by ultrasonography in 47 (23 females, 24 males) healthy, fully-dentate young adults who volunteered for the study. The measurements for each individual were performed twice for the masseter muscle: during relaxation and during maximal clenching. Standardized lateral cephalograms of the subjects were traced to determine their facial morphology. The data obtained from the lateral cephalograms were used to divide the subjects into three groups according to their vertical facial pattern: low angle (n = 14), high angle (n = 17) and normal (n = 16). In the low angle group, the mean masseter muscle thickness was 15.20 (+/- 1.90) mm under relaxed conditions and 16.31 (+/- 2.18) mm during maximal clenching. In the high angle group, the respective measurements were 13.29 (+/- 2.52) mm and 14.72 (+/- 2.63) mm. In the vertically normal group, they were 13.56 (+/- 1.95) mm and 14.57 (+/- 1.83) mm. There was no relationship between vertical growth of the face and the thickness of the investigated muscles of facial expression. Masseter muscle thickness was found to be significantly correlated to vertical facial pattern and BMI, showing that individuals with a thick masseter had a vertically shorter facial pattern, whereas the muscles of facial expression showed no relationship with vertical facial pattern.

Infantile myofibromatosis: unusual diagnosis in an older child

This manuscript describes the unusual presentation of infantile myofibromatosis (IM) in an older child with its diagnosis and management. An 8-year-old girl presented with a painless, rapidly expanding malar mass. CT demonstrated an erosive soft tissue lesion and needle biopsy was nondiagnostic. Complete excision returned the pathologic diagnosis of IM. The patient had no complications and no evidence of recurrence at 1 year. Almost 90% of IM cases present by age two and IM in older children is highly unusual. The solitary form of IM is most common and its treatment is complete excision with an excellent prognosis.

Zygomatic arch reconstruction with autogenous rib bone graft in a post irradiated patient -- a case report

Reconstruction of zygomatic arch using an autogenous free non-vascularised bone graft is presented. The zygomatic arch was resected along with the masseter and part of temporalis muscle following a histologically diagnosed case of chondrosarcoma. She received radiotherapy 3 weeks post-operatively to the site. The resultant facial asymmetry was unacceptable to the patient. She was therefore rescheduled for reconstruction of the zygomatic arch despite the anticipated attendant risk of avascular bed for the graft. Bone grafting was done 44 months post irradiation and the patient had been followed up for 38 months without evidence of rejection. We evaluated other sites of possible bone of similar contour and thickness to the zygomatic arch; we found the rib most suitable, despite the poor quality of rib as graft material, because it is a dense, thick bicortical bone with low proportion of cancellous bone, although it is the second most favoured donor site for free bone graft. The advantages of the rib as a graft are that it presents a contour that could be shaped to fit many defects, it is available in sufficient length up to 12-18 cm to fit large defects, the donor site regenerates when the periosteum is preserved.

Morphologic characteristics of masseter muscle in cleidocranial dysplasia: A report of 3 cases

Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia. In order to define the morphologic characteristics of the masseter muscle incidental to bone abnormalities, we present 3 cases of CCD with the masseter muscle thickness and maxillofacial bone abnormalities, using computed tomography (CT) and panoramic radiographs. In CCD patients (a) the masseter muscles were less thick than in age- and sex-matched control subjects, (b) the zygomatic arch was discontinuous with the hypoplastic zygomatic bone, (c) the ascending ramus of the mandible had parallel-sided borders, and (d) the coronoid process pointed upwards and/or posteriorly. We have concluded the masseter muscles are less thick than normal, alongside the maxillofacial bone abnormalities in CCD patients.

Computed tomographic features of bilateral coronoid process hyperplasia with special emphasis on patients without interference between the process and the zygomatic bone

OBJECTIVE

To reveal computed tomography (CT) features of patients with coronoid process hyperplasia without interference between the process and the zygomatic bone.

STUDY DESIGN

A case-control study was designed. Thirteen cases without interference (2 male and 11 female, 28-56 years old) and 65 controls were sampled from a patient database. Differences in CT features were analyzed between the 2 groups regarding the following 7 points of 5 regions: configuration of the coronoid process, vertical level of the coronoid process, the distance between the bilateral zygomatic arches, thickness of the temporal muscle, anteroposterior width of the temporal muscle, thickness of the temporal muscle tendon, and thickness of the masseter muscle. Cluster analysis was applied to differentiate between individuals.

RESULTS

All cases had bilateral hyperplastic change of the coronoid process. Differences were found between the cases and controls in 6 of 7 CT features with the exception of temporal muscle thickness. All incidences of significant difference showed larger values in the cases. All cases were clustered into the same group and were differentiated from the controls.

CONCLUSION

CT features appeared to be effective for diagnosis of this condition, and these patients should be put into the same category under the diagnosis of coronoid process hyperplasia.

Craniofacial measurements based on 3D-CT volume rendering: implications for clinical applications

OBJECTIVES

This study was designed to determine the precision and accuracy of anthropometric measurements using three-dimensional computed tomography (3D-CT) volume rendering by computer systems for craniofacial clinical applications, and to compare the craniometric landmarks using bone and soft tissue protocols.

METHODS

The study population consisted of 13 cadaver heads that were examined with spiral CT. The archived CT data were transferred to a workstation, and 3D-CT volume rendered images were generated using computer graphics tools. Linear measurements (n = 10), based upon conventional craniometric anatomical landmarks (n = 08), were identified in 2D-CT and in 3D-CT images by two radiologists twice each independently, and then performed by 3D-CT imaging using a computer graphics systems using bone and soft tissue protocols. In total, 520 imaging measurements were made. The soft tissues were subsequently removed from the cadaver heads and the measurements were repeated using an electromagnetic 3 Space trade mark digitizer.

RESULTS

The results demonstrated no statistically significant difference between interobserver and intraobserver measurements or between imaging and physical measurements in both 3D-CT protocols. The standard error was found to be between 0.45% and 1.44% for all the measurements in both protocols, indicating a high level of precision. Furthermore, there was no statistically significant difference between imaging and physical measurements (P > 0.01). The error between the mean actual and mean 3D-based linear measurements was 0.83% for bone and 1.78% for soft tissue measurements, demonstrating high accuracy of both 3D-CT protocols.

CONCLUSIONS

3D-CT volume rendering images using craniometric measurements can be used for anthropological studies involving craniofacial applications.

Comparison of Accuracy of Three-Dimensional Spiral Computed Tomography, Standard Radiography, and Direct Measurements in Evaluating Facial Fracture Healing in a Rat Model

Complex maxillofacial fractures demand a detailed understanding of the three-dimensional (3D) pattern of injury. Evaluation of the outcome of the facial fracture repair additionally requires optimal demonstration of fracture gap, bony union, fibrous callus or incorporation of fracture ends, presence of incomplete fusion, or pseudoarthrosis. Although 3D computed tomography (CT) is reliably used for the diagnosis of complex facial fractures, its value in facial fracture healing is unknown. An experimental study was conducted to determine the accuracy of 3D spiral CT scans in evaluating facial fracture healing during the early and late postoperative periods. In 10 adult Wistar Albino rats, a standardized bone defect (3 mm) was created within the mid portion of each zygomatic arch (n = 20). At 10 and 20 weeks postfracture, gap distance displayed by 3D CT and plane radiography (posteroanterior) were measured. At 20 weeks postfracture, intraoperative measurement was also performed. A comparison between 3D CT, radiography, and intraoperative findings was performed. At 10 weeks postfracture, the fracture sites displayed larger bone defects in imaging with 3D CT than with plane radiography. The difference between groups was statistically significant (P < 0.05). The mean defect size imaged by 3D CT was 0.91 +/- 0.82 mm (standard deviation) and by plane radiography was 0.42 +/- 0.16 mm. At 20 weeks postfracture, the mean defect size imaged by 3D CT was 0.56 +/- 0.64 mm, and by plane radiography was 0.38 +/- 0.22 mm. The difference between groups was not statistically significant (P > 0.05). The defect size imaged by both plane radiography and 3D CT was significantly less than the measurement obtained from the intraoperative assessment (P < 0.05). It was concluded that 3D CT has limited benefit in the detection of newly formed bone at week 10 and in the detection of fibrous callus, which can eventually give rise to the bony tissue. Plane radiography is more valid during the early postoperative period (week 10), because it can detect the fibrous callus and newly formed bone more precisely. Gap distance between fracture ends could be determined by 3D CT accurately at week 20, although there was a tendency, which was not statistically significant, to overestimate the amount of bone defect measured by 3D CT when compared with that of plane radiography.

Craniofacial abnormalities in a murine knock-out model of mucopolysaccharidosis I H: a computed tomography and anatomic study

The genetic mucopolysaccharidoses are a group of lysosomal storage diseases in which mucopolysaccharides (glycosaminoglycans) accumulate as the result of a malfunction or lack of a lysosomal degradation enzyme. There are currently seven known forms of mucopolysaccharidoses. Type I results from an enzymatic deficiency of alpha-L-iduronidase. There are three subtypes of mucopolysaccharidoses I that are commonly recognized: Hurler syndrome, Hurler-Scheie syndrome, and Scheie syndrome. Of the three subtypes, Hurler syndrome has the most severe clinical picture. Craniofacial anomalies and cognitive impairment are some of the more pronounced features of Hurler syndrome. Hurler syndrome has been described in cats, dogs, mice, and human beings and is inherited as an autosomal recessive trait. The biochemical nature of the disease is preserved across species lines. Clinically, the disease has similar effects in human beings and animals. It has been difficult to reverse the phenotype of the disease even with replacement of the defective alpha-L-iduronidase enzyme. The purpose of this study is to characterize the cranio-facial differences in the murine knock-out model of Hurler syndrome objectively. Twenty-three measurements were taken from computed tomographic scans in a coronal and sagittal plane on 24 black C57/B6 knock-out Hurler syndrome mice. The seven statistically significant measurements are width of the cervical canal, height of the foramen magnum, width between the external auditory canals, width of the skull base at the mandibular condyles, midocular distance, spread of the mandibular condyles, and width of the zygoma at the maxilla. This information now provides researchers with objective data from living Hurler syndrome-affected mice that will allow them to follow therapies directed at improving craniofacial outcomes for any therapy over time.

Aplasia of zygomatic arch and dislocation of temporomandibular joint capsule in Treacher-Collins syndrome: three-dimensional reconstruction of computed tomographic scans

Seven patients with Treacher-Collins syndrome were studied. All of patients were children or teenagers. Helical CT scanner (Toshiba) was used to reconstruct zygomatic arch and temporomandibular joint capsule on lateral aspect of temporal bone in five patients of microtia and atresia of both ears and two patients of narrow ear canals of both ears without microtia.Three-dimensional reconstructions of computed tomography on lateral aspect of temporal bone demonstrated various congenital abnormality including aplasia of zygomatic arch in seven patients and dislocation of temporomandibular joint capsule in seven patients.