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At least 19 recordsLinked to original sources
PubMed2006

Predicting zygoma fractures from baseball impact.

The purpose of this study is to develop injury risk functions that predict zygoma fracture based on baseball type and impact velocity. Zygoma fracture strength data from published experiments were mapped with the force exerted by a baseball on the orbit as a function of ball velocity. Using a normal distribution, zygoma fracture risk functions were developed. Experimental evaluation of these risk functions was performed using six human cadaver tests and two baseballs of different stiffness values. High speed video measured the baseball impact velocity. Post test analysis of the cadaver skulls was performed using CT imaging including three-dimensional reconstruction as well as autopsy. The developed injury risk functions accurately identify the risk of zygoma fracture as a result of baseball impact. The experimental results validated the zygoma risk functions at the lower and upper levels. The injuries observed in the post test analysis included fractures of the zygomatic arch, frontal process and the maxilla, zygoma suture, with combinations of these creating comminuted, tripod fractures of the zygoma. Tests with a softer baseball did result in injury but these had fewer resulting zygoma bone fragments and occurred at velocities 50% higher than the major league ball.

Baseball↗
PubMed2001

Measurement of the maxilla and zygoma as an aid in installing zygomatic implants.

PURPOSE: This study used maxillary and zygomatic measurements to obtain information for installing zygomatic implants. PATIENTS AND METHODS: Angular and linear distances between the maxilla and the zygoma were measured in 12 cadavers (n = 22 sides) classified into short and tall groups by height (140 to 159 cm and 160 to 180 cm, respectively). RESULTS: Based on mean and standard deviation values, the installation angle of zygomatic implants was between 43.8 degrees and 50.6 degrees. The distance between the crest of the maxillary alveolar process near the palate and the jugale (Ju) point of the zygoma was between 44.3 and 54.3 mm. The minimum distance between the most lateral corner of the maxillary sinus and the Ju point was 6.41 mm, and the minimum anteroposterior length of the zygoma was 5.68 mm in the shorter group. CONCLUSIONS: When the installation angle of zygomatic implants is 43.8 degrees or less, perforation of the maxilla and the zygoma or the infratemporal fossa must be avoided. When the angle is 50.6 degrees or more, perforation of the orbital floor must be avoided. Special attention is needed to ensure osseointegration in shorter patients, because the distance between the most lateral corner of the antrum supporting the zygomatic implant and the Ju point is 10 mm or less. The apex of the implant is 3.75 mm in diameter, and the thickness of the zygoma must be 5.75 mm or more. The threads of the implant must not be exposed from the zygoma in shorter patients.

Body Height↗
PubMed2006

Minimally invasive zygoma reduction.

BACKGROUND: It is universally accepted that zygoma reduction is one of the best strategies for facial contouring for Asian patients, and many studies have been conducted regarding this subject. However, these studies have continued to perform the zygoma reduction by sectioning the complete malar eminence to fix it into a new location, which requires a wide range of periosteum dissection to expose the bone sufficiently for correct osteotomy. METHODS: In this study, with the help of a new instrument, the authors have applied a new minimally invasive, blind technique to zygoma reduction with multiple scoring and molding. The minimally invasive zygoma reduction was performed through a 5-mm intraoral stab incision, and the authors have operated on over 271 male and female patients. RESULTS: As a result, the authors could reduce the operation time and the postoperative swelling and have achieved greater cosmetic effects and enlarged indications compared with those of conventional methods. The well-known complications of cheek drooping, facial nerve injury, temporomandibular joint injury, and malunion were absent. In particular, because of the relatively reduced swelling, most of the patients could resume activities of daily life within 3 days after the operation. CONCLUSION: Therefore, the authors recommend this new minimally invasive zygoma reduction as another option for zygoma reduction.

Adult↗
PubMed2004

A clinical evaluation of the Zygoma fixture: one year of follow-up at 16 clinics.

PURPOSE: To evaluate treatment outcome with Zygoma fixtures (Nobel Biocare, Göteborg, Sweden) with regard to fixture survival, patient satisfaction, and function of prosthesis replacement. MATERIALS AND METHODS: The treatment outcome of 76 patients treated with 145 Zygoma fixtures at 16 centers was evaluated. Patient's and dentist's evaluations of the functional and aesthetic outcome of the treatment were assessed at delivery of prosthesis and at the 1-year follow-up visit. At the 1-year follow-up visit, the status of the peri-implant mucosa around the abutments and the amount of plaque were registered. RESULTS: Sixty-six of the 76 patients, with 124 Zygoma fixtures supporting the prosthetic restorations, were evaluated at the 1-year follow-up. The overall survival rate for the Zygoma fixtures was 97.9% after 1-year of follow-up. Eighty percent of the patients were fully satisfied with both aesthetic and functional outcome at the time of prosthetic insertion and at the 1-year follow-up. All reported data from the dentists, with the exception of one restoration with several abutment screw loosenings, scored from acceptable to excellent for the aesthetic and functional outcome of the treatment. The status of peri-implant mucosa was recorded as normal in approximately 60% of the sites. Plaque, when present, was more often detected on the palatal surfaces compared with the buccal surfaces. CONCLUSION: This 1-year follow-up of Zygoma fixtures has shown good results with an acceptable number of minor complications and a majority of satisfied patients.

Adult↗
PubMed2004

Zygoma fixture in the management of advanced atrophy of the maxilla: technique and long-term results.

Despite refinements in surgical technique, including bone grafting and sophisticated prosthetic reconstructions, there are limitations to what can be achieved with bone-anchored fixed prostheses in patients with advanced atrophy of the maxillae. A new approach was suggested by a long-term study on onlay bone grafting and simultaneous placement of a fixture based on a new design: the zygoma fixture, and the aim of this study was to assess its potential. Twenty-eight consecutive patients with severely resorbed edentulous maxillae were included, 13 of whom had previously had multiple fixture surgery in the jawbone that had failed. A total of 52 zygoma fixtures and 106 conventional fixtures were installed. Bone grafting was deemed necessary in 17 patients. All patients have been followed for at least five years, and nine for up to 10 years. All patients were followed up with clinical and radiographic examinations, and in some cases rhinoscopy and sinoscopy as well. Three zygoma fixtures failed; two at the time of connection of the abutment and the third after six years. Of the conventional fixtures placed at the time of the zygoma fixture, 29 (27%) were lost. The overall prosthetic rehabilitation rate was 96% after at least five years of function. There were no signs of inflammatory reaction in the surrounding antral mucosa. Four patients with recurrent sinusitis recovered after inferior meatal antrostomy. To conclude, the zygoma fixture seems to be a valuable addition to our repertoire in the management of the compromised maxilla.

Bone Transplantation↗
PubMed2004

Ballistic impact to the forehead, zygoma, and mandible: comparison of human and frangible dummy face biomechanics.

BACKGROUND: Currently, there is a greater use of nonlethal force in law enforcement and military operations. Because facial injuries have been observed, there is a need to understand the human response to ballistic impacts involving various regions of the face. This study aimed to establish blunt ballistic response corridors for high-speed, low-mass facial impacts to the forehead, zygoma, and mandible, and to determine how these responses compare with those of the frangible Hybrid III headform. Correlation of the human and dummy responses allows injury risk assessment for munitions used in the field. METHODS: Facial impacts to the forehead, zygoma, and mandible of six cadavers at 42 +/- 10 m/sec were conducted using a 25- to 35-g projectile 37 mm in diameter that was instrumented with an accelerometer to determine impact force. High-speed video analysis determined penetration of the projectile, and autopsy determined the facial fractures. Force and deflection were normalized for the 50% tile response, and corridors were determined for blunt ballistic impacts. Similar tests were conducted on the frangible face of the Hybrid III dummy. RESULTS: Peak normalized force of 3.5 +/- 0.9 kN on the forehead and 3.0 +/- 1.0 kN on the mandible did not result in fractures, whereas an impact force of 2.3 +/- 0.5 kN on the zygoma caused anterior maxilla fractures. The frangible Hybrid III face developed similar force levels, but with less penetration of the projectile. Its stiffness was 43% greater than that of the cadaver. CONCLUSIONS: Higher impact force can be tolerated on the forehead and mandible than on the zygoma. Normalized force-deflection and force-time corridors were established for the human response. The frangible Hybrid III face is an effective surrogate for assessing ballistic injury risks, but greater compliance would make it more biofidelic. Initial human tolerance levels of 6.0 kN for the forehead, 1.6 kN for the zygoma, and 1.9 kN for the mandible have been established for ballistic impacts to the face.

Aged↗
PubMed2005

Zygoma implant-supported midfacial prosthetic rehabilitation: a 4-year follow-up study including assessment of quality of life.

OBJECTIVE: Successful prosthetic rehabilitation is crucial for quality of life in cases of large maxillary defects when surgical reconstruction is not advisable because of general health or patient refusal. For this purpose, the extended indications for Zygomaticus fixtures in different defect types were evaluated. PATIENTS AND METHODS: Twelve patients received 28 zygoma implants and 23 dental implants (if a segment of alveolar process was available) and were followed-up 14-53 months. Zygoma implants were positioned classically in the maxillary molar region and to reduce leverage, a premolar and a canine position was developed. The quality of life was assessed by a validated questionnaire after complete rehabilitation. RESULTS: Cumulative zygoma implant survival was 82%. Three losses occurred because of persistent infection and gradual loosening. Lost implants were immediately replaced in adjacent bone. Insufficient implant length within soft tissue reconstructions was prone to chronic infection by pocketing and recurrent overgrowth of granulating tissue. Longer implants were free of soft tissue inhibition, yet prone to overloading and high leverage in cases when no anterior alveolar process and dental implants were present. Zygoma implant success was therefore 71%, including the new premolar and canine Zygomaticus fixture-position. Periotest values increased from 0 to +7 to the fourth year, peri-implant bleeding and plaque index were decreasing from 56% to 0% and 33% to 0%, respectively, and good general quality of life with the priorities on chewing and activity was noted. CONCLUSION: Zygoma implants can reliably anchor the midfacial maxillary prostheses and enable a quality of life comparable with autologous maxillary reconstruction. They can be replaced immediately if local infection or loosening should occur. A premolar and canine position reduce leverage when no anterior alveolar process is present. The patient can alternatively be provided with dental implants.

Adult↗
PubMed2004

Infraorbital nerve injury associated with zygoma fractures: documentation with neurosensory testing.

Persistent sensibility abnormalities after correction of zygoma fractures indicate injury to the infraorbital nerve and may produce pain. To investigate this, a retrospective study of 25 patients who had undergone surgical correction of a zygoma fracture was performed. Bilateral neurosensory measurements were obtained with the Pressure-Specified Sensory Device (Sensory Management Services, Baltimore, Md.). Seven of the 25 patients had required orbital floor reconstruction. Each patient had undergone fracture correction at least 6 months earlier and was interviewed, at the time of sensibility testing, regarding symptoms related to the fracture. The data were evaluated by a blinded examiner, from a separate clinical facility, who attempted to predict the side of the fracture and the degree of zygoma displacement on the basis of measurements of sensibility of the paranasal, upper lip, and zygomaticotemporal areas. Seventy-six percent of patients demonstrated abnormal sensibility on the side of the zygoma fracture, compared with the contralateral side. Sensibility was abnormal for 100 percent of the patients who required orbital floor reconstruction. Seventy-four percent of patients with abnormal sensibility reported symptoms related to the fracture. Eighty percent of the zygoma fractures were correctly identified, with respect to the side of the fracture, by the blinded examiner on the basis of the neurosensory measurements alone (p < 0.005). Predictions proved correct for 91 percent of the patients with widely displaced fractures and none of the patients with nondisplaced fractures. The results of this study suggest that neurosensory testing is an important clinical adjunct for the evaluation of patients with facial pain or dysesthesia after facial fracture reconstruction. The results suggest the need to develop algorithms for the diagnosis and treatment of trigeminal nerve injuries after craniofacial trauma. This approach could also be applicable to dysesthesia or pain after aesthetic facial surgical procedures.

Cranial Nerve Injuries↗
PubMed1989

[Clinical study on surgical treatment of zygoma fractures].

This is a retrospective statistical study on zygoma fractures. This study was based on 83 cases of zygoma fractures treated surgically in Dept. of Oral and Maxillofacial Surgery, Chungnam National University Hospital from May, 1985 to Sep., 1988. Among the many items the type of fractures and surgical methods were emphasized. For convenience sake, the zygoma fracture were classified according to Knight & North's classification. The results obtained are as follows: 1. The zygoma fractures occupied 31.9% of facial bone fractures. 2. The main age group were the second decade (37.5%) and the third decade (30.0%) and the ratio of mail and femail was 5.7:1. 3. The main contributing causes of fractures was traffic accident (71.3%). 4. The zygoma fractures were classified in 6 Group. Group 1. Undisplaced fractures were 8.4%. Group 2. Only arch fractures were 9.6% Group 3. Tripod with unrotated body were 32.5% Group 4. Tripod with medially rotated body were 20.5% Group 5. Tripod with laterally rotated body were 9.6% Group 6. Complex fractures were 19.2% 5. Fixation were required in 69 cases (83.1%) after adequate reduction. 6. Fixation area the most frequently used was zygomaticofrontal suture (71.1%), and infraorbital rim (43.3%), zygomatic arch (16.9%), zygomatic buttress (6%) were followed.

Adolescent↗
PubMed2006

[Segmental reconstruction of maxillary defects by arced distraction osteogenesis of zygoma].

OBJECTIVE: To study the possibility of segmental maxillary regeneration by arced distraction osteogenesis of zygoma. METHODS: The distraction of zygoma with the internal arced devices was performed in 2 dogs to simulate the reconstruction of maxillary defect. The zygoma was distracted about 12 mm, and the process of new bone formation was studied by histology and scanning electron microscopy. RESULTS: The transport disk was distracted about 12 mm around the arc. After 8 weeks of consolidation, the density of new bone was close to that of normal bone. CONCLUSIONS: The segmental maxillary regeneration by arced distraction osteogenesis of zygoma is possible.

Animals↗
PubMed1997

Computer-aided navigation in secondary reconstruction of post-traumatic deformities of the zygoma.

Augmented reality technology was used in 5 patients for secondary reconstruction of post-traumatic unilateral deformities of the zygomaticomaxillary complex. Three electromagnetic sensors interfaced to a computer-aided navigation system (ARTMA Biomedical Inc.) were utilized. The computer navigation procedure was planned by drawing graphic lines on the CT scan at the level of the zygomatic arch, representing the outer surface of the zygoma. The desired position of the displaced zygoma was planned by mirroring from the healthy side, using a virtual mid-sagittal plane. These virtual graphics were presented intraoperatively on a TV monitor and also on the surgeon's see-through head-mounted display. Correct reduction was assumed when the virtual line representing the position of the zygoma before the osteotomy reached the virtual line defined preoperatively as the desired position. The advantages of the technique presented are that a complete exposure of the zygomatic bone is no longer necessary, and coronal and subciliary incisions may be avoided unless enophthalmos correction has to be carried out, which was in fact necessary in 2 patients. The results of zygomatic reconstruction have been satisfactory in all 5 patients.

Adult↗
PubMed2003

Accuracy of drilling guides for transfer from three-dimensional CT-based planning to placement of zygoma implants in human cadavers.

The accuracy of surgical drilling guides was assessed for placement of zygoma implants. Six zygoma fixtures of length 45 mm (Nobel Biocare, Göteborg, Sweden) were placed in three formalin-fixed human cadavers using surgical drilling guides. The fabrication of these custom-made drilling guides was based on three-dimensional computerized tomography (3D-CT) data for the maxillary-zygomatic complex. The installation of the implants was simulated preoperatively using an adopted 3D-CT planning system. In addition, anatomical measurements of the zygomatic bone were performed on the 3D images. The preoperative CT images were then matched with postoperative ones in order to assess the deviation between the planned and installed implants. The angle between the planned and actually placed implants was < 3 degrees in four out of six cases. The largest deviation found at the exit point of one of the six implants was 2.7 mm. The present study showed that the use of surgical drilling guides should be encouraged for zygoma implant placement because of the lengths of the implants involved and the anatomical intricacies of the region.

Adult↗
PubMed2003

Image-based planning and clinical validation of zygoma and pterygoid implant placement in patients with severe bone atrophy using customized drill guides. Preliminary results from a prospective clinical follow-up study.

The zygoma implant has been designed for those situations where there is insufficient bone in the upper jaw, which would otherwise require onlay or inlay (sinus) bonegrafts. The aim of the study was to present and validate a planning system for implant insertion based on preoperative CT imaging. It allows the surgeon to determine the desired position of different kinds of implants. Finally a customized drill guide is produced by stereolithography. In this study, zygoma, pterygoid and regular platform implants were used. The treatment protocol is validated through 12 case studies, selected at random from the total patient group (n=29 patients). From postoperative images, the exact implant location is determined and the deviation of axes between planned and inserted implants is calculated. In this in vivo study, displacements, varying according to the type of implant and the location of the implants, were observed. From a clinical standpoint, most of the inserted implants were judged to be adequately sited. A prospective clinical follow-up study was performed on all 29 patients. Although all patients presented with severe maxillary atrophy, excellent cumulative survival rates (92%) for the zygoma implants and 93% for regular platform implants have been obtained.

Adult↗
PubMed1995

Aesthetic and functional reconstruction in intraosseus hemangiomas of the zygoma.

The incidence of intraosseus hemangiomas is very low. The mandible, the zygoma, the maxilla, and the frontal bone are the most frequent areas of localization in the craniomaxillofacial region. Surgery, without preoperative embolization, is always the best treatment for intraosseus hemangiomas of the zygoma. The radical removal of the tumor frequently causes a contour defect that has to be corrected. Calvarial grafts provide a good solution to the problem of reconstruction of bone loss. They are easy to prepare, near to the implant zone, and they do not require changes in the patient's position during the operation. The implants fixed by micro- and minifixation systems provide a good functional and aesthetic result. We, after a review of the literature on intraosseus hemangiomas of the craniomaxillofacial region, report two cases of intraosseus hemangiomas of the zygoma in which removal of the tumor and reconstruction with calvarial grafts have been performed.

Adult↗
PubMed1998

Transcutaneous reduction and external fixation for the treatment of noncomminuted zygoma fractures.

PURPOSE: This study evaluated the effectiveness of the treatment of noncomminuted monofragment zygoma fractures with closed reduction using transcutaneous threaded pins and an external fixation device instead of open reduction and internal rigid fixation. PATIENTS AND METHODS: In 46 patients, transcutaneous pin was inserted into the center of the fractured zygoma, and the segment was reduced by moving the pin to counteract the initial vector force of injury. After reduction, the fractured segment was immobilized by the external fixation device for 9 to 14 days. RESULTS: All patients except one showed accurate fracture reduction without malunion or any complications. CONCLUSION: This method has advantages over the conventional closed methods in the management of uncomplicated noncomminuted fractures of the zygoma.

Adolescent↗
PubMedDate not supplied

Fractured zygomas.

BACKGROUND: The purpose of this paper is to provide a review, based on collected data, on the topic of "fractured zygoma". The review is presented under the headings of epidemiology, fracture patterns, treatment modalities and complications. Throughout the paper comparison is made with published data from around the world. METHODS: A 10-year retrospective audit was undertaken of all hospitalized patients, at the Royal Hobart Hospital, Tasmania, who had sustained a fractured zygoma. All Le Fort fractures involving the zygoma were excluded. RESULTS: A total of 263 fractures was sustained, largely due to assault. Alcohol was a significant contributing factor. Tetrapod fractures were the most frequent type of fractures witnessed. Plating was the most frequently employed fixation. Inferior orbital nerve dysfunction and other complications were seen in 24.6% and 20.7% of follow-up cases, respectively. Open reductions were nearly 4 times more likely to be accompanied by complications if inferior orbital nerve dysfunction was excluded. CONCLUSIONS: Both closed and open reductions are good treatment modalities and were used in near equal numbers of patients. There is a higher incidence of postoperative facial deformity in the closed reduction group, but more complications related to the incisions in the open reduction group. Open reduction and internal fixation is advocated for the unstable, markedly displaced or comminuted fractures. Silastic sheeting is a favoured graft for repair of the associated orbital floor defects and is associated with few complications.

Accidents, Traffic↗
PubMed1997

Endoscopic reduction and internal cyanoacrylate fixation of the zygoma.

OBJECTIVE: The objective of this study was to explore the feasibility of utilizing n-butyl-2 cyanoacrylate, a polymeric adhesive, for fixation of the zygoma after fracture displacement. DESIGN: A human cadaveric model was developed and used. SETTING: All experimentation was performed in the anatomy laboratory at the University of Western Ontario, London, Ontario. METHODS: The stability of zygomatic fractures endoscopically reduced and fixed with cyanoacrylate was compared to that of contralateral fractures treated by traditional closed reduction. The load to failure of each repaired fracture was established using a previously described linear-load applicator. MAIN OUTCOME MEASURES: The primary outcome measure was load to failure (kg). RESULTS: The technique was easily performed on all specimens and is described. Our data show that a zygoma, reduced and fixed in this manner, tolerates an 18-fold greater load to failure than does a zygoma treated by closed reduction alone. Traditional closed reduction of complete fracture dislocations at all three zygomatic suture lines tolerates a mean load to failure of 0.95 kg. The use of cyanoacrylate fixation increases the mean load to failure to 17.6 kg. CONCLUSIONS: Endoscopic reduction and cyanoacrylate fixation of zygomatic fractures deserve investigation in the clinical setting.

Cadaver↗
PubMed1989

Three-point alignment of zygoma fractures with miniplate fixation.

Over the years, depression of the malar eminence has been one of the most persistent complications of zygoma fractures, regardless of the fixation technique used. The use of a sublabial incision for direct visualization and alignment of the fracture lines at the infraorbital rim and lateral maxillary buttress is described. When coupled with single miniplate fixation of the zygoma across the frontozygomatic suture, the sublabial approach results in improved reduction of the fractures with rigid stabilization. Our experience with this approach, as well as with two-point wire fixation and with miniplate fixation without sublabial exposure, is reviewed.

Adolescent↗