Postoperative computed tomography scan study of the pterygomaxillary separation during the Le Fort I osteotomy using a micro-oscillating saw.

PURPOSE: The objective of the study was to evaluate the type of pterygomaxillary separation that occurs with use of a micro-oscillating saw. PATIENTS AND METHODS: Sixteen patients underwent a postoperative computed tomography scan. RESULTS: Ideal or near-ideal separations occurred on 26 of 32 sides (81%), while low-level fractures occurred in 6 of 32 sides (19%). No high-level fractures of the pterygoid plates, or fractures extending to the base of the skull or orbit, were seen. There was a striking difference in the number of ideal separations on the right-hand side (94%), compared with the left-hand side (50%), probably because of the greater difficulty of a right-handed surgeon positioning the saw blade correctly on the left side without bending the thin flexible saw blade backward. CONCLUSION: In view of the high percentage of ideal pterygomaxillary separations achieved using a micro-oscillating saw, and the absence of high-level pterygoid plate fractures extending to the base of the skull, this technique is recommended for the pterygomaxillary dysjunction.

Alternative approaches to pterygomaxillary separation.

Pterygoid plate fractures, resulting from the pterygomaxillary separation in a Le Fort I osteotomy, may be associated with untoward fractures that extend to the base of the skull and orbit and which can lead to rare but significant complications. Five alternative approaches to the pterygomaxillary dysjunction were studied in 50 fresh cadavers. The results of this study show that the use of a curved Obwegeser osteotome to achieve the pterygomaxillary dysjunction should be abandoned, as it leads to an unacceptably high incidence of high-level pterygoid plate fractures at, or near, the base of the skull. The best results were obtained with a Stryker micro-oscillating saw.

Ophthalmic complications associated with orthognathic surgery.

Ophthalmic complications are rare following maxillary osteotomies. Potential complications include a decrease in visual acuity, extraocular muscle dysfunction, neuroparalytic keratitis, and nasolacrimal problems involving both an increase or a decrease in tearing. Ophthalmic injuries appear to be primarily mediated through indirect injuries to neurovascular structures occurring from traction, compression, or contrecoup injuries from forces transmitted during the pterygomaxillary dysjunction using an osteotome or from fractures extending to the base of the skull or orbit associated with the pterygomaxillary dysjunction or the maxillary downfracture. A review of the literature of previous ophthalmic complications as well as eight new cases are reported. The possible etiologic basis for these injuries is discussed in detail as well as treatment possibilities when appropriate.

Trigeminocardiac reflexes: maxillary and mandibular variants of the oculocardiac reflex.

Three case reports are presented to illustrate the existence and importance of reflex bradycardic responses that can occur during maxillofacial surgical procedures. All three patients were healthy young adults undergoing operations which did not include any manipulation of orbital structures. After the patients had been anaesthetized for some time and were haemodynamically stable, profound bradycardia or ventricular asystole occurred suddenly in response to manipulations of the bony structures of the maxilla or mandible, or dissection of, or traction on, the attached soft tissue structures. The parasympathetic supply to the face is carried in the trigeminal nerve. Alternative afferent pathways must exist via the maxillary and/or mandibular divisions, in addition to the commonly reported pathway via the ophthalmic division of the trigeminal nerve in the classic oculocardiac reflex. The efferent arc involves the vagus, regardless of which branch of the trigeminal nerve transmits the afferent impulses. All patients undergoing maxillofacial procedures should be monitored carefully for reflex bradycardia and ventricular asystole.

Hemorrhage following mandibular osteotomies: a report of 21 cases.

Hemorrhage associated with mandibular osteotomies, especially to the extent that it becomes life threatening, is a rare occurrence and its risk is less than that following maxillary orthognathic surgery. Twenty-one cases of significant bleeding following mandibular sagittal split ramus osteotomies, vertical and oblique ramus osteotomies, and genioplasties are presented. Life-threatening hemorrhage associated with mandibular osteotomies is primarily an intraoperative problem and the incidence of major postoperative and recurrent hemorrhage is not as great as following maxillary osteotomies. Suggestions for the avoidance and treatment of these bleeding complications are discussed.

Major vascular complications of orthognathic surgery: false aneurysms and arteriovenous fistulas following orthognathic surgery.

False aneurysms and arteriovenous fistulas are rare complications of orthognathic surgery. The vessel most commonly involved with false aneurysms following mandibular surgery is the internal maxillary artery, and this vessel, especially the sphenopalatine branch, may also be involved following maxillary surgery. An unusual factor in the presentation of false aneurysms following Le Fort I osteotomies is an initial episode of epistaxis occurring greater than 2 weeks postoperatively. Arteriovenous fistulas following orthognathic surgery are more apt to involve large vessels, especially the internal carotid artery. Embolization procedures are the treatment of choice for false aneurysms and arteriovenous fistulas in the maxillofacial region following orthognathic surgery.

Paradental cysts on mandibular first molars in children: report of five cases.

Five cases of paradental cyst are reported which were found to arise buccal to a mandibular first permanent molar in children under the age of 10 years. The justification for calling these lesions paradental cysts is discussed. Since the histopathological findings of this lesion are non-specific, the clinical and radiographic features are of prime importance in diagnosis when the lesion occurs in this site in patients of this age. Buccal swelling adjacent to a mandibular first molar which is partially erupted or which has a soft tissue cover is a common clinical finding. Occlusal projections generally give the best presurgical diagnostic information, demonstrating the presence of a radiolucent lesion with a periosteal bone reaction buccal to the involved tooth and displacement of the roots to the lingual. The cyst can be successfully treated by simple enucleation without disturbing the associated tooth.

Major vascular complications of orthognathic surgery: hemorrhage associated with Le Fort I osteotomies.

Major intraoperative or postoperative bleeding associated with Le Fort I osteotomies can be venous and/or arterial in nature. Arterial hemorrhage generally involves the maxillary artery and its terminal branches. Arterial hemorrhage tends to be more persistent and can be recurrent, which makes it more difficult to manage. Postoperative bleeding following Le Fort I osteotomies generally presents as epistaxis and usually occurs initially within the first 2 weeks following surgery. Treatment modalities that have been used to successfully arrest postoperative hemorrhage include anterior and/or posterior nasal packing; packing of the maxillary antrum; reoperating with clipping or electrocoagulation of bleeding vessels, or the use of topical hemostatic agents in the pterygomaxillary region; external carotid artery ligation; and selective embolization of the maxillary artery and its terminal branches.

Aseptic necrosis of the mandible: report of two cases.

It appears that clinically significant aseptic necrosis following mandibular osteotomies is a more infrequent occurrence than that following maxillary surgery because only two cases were reported in a questionnaire dealing with major vascular complications following orthognathic surgery. Significant necrosis is unlikely to occur if a surgeon follows the basic principle of stripping the minimal amount of mucoperiosteum and muscle attachment from the osteotomized segments commensurate with the successful completion of the osteotomies.

Aseptic necrosis following maxillary osteotomies: report of 36 cases.

The sequelae of insufficient vascularity following maxillary orthognathic surgery can vary from loss of tooth vitality, to periodontal defects, to tooth loss, to loss of major maxillary dentoalveolar segments. The results of a questionnaire mailed to oral and maxillofacial surgeons found this complication was most likely to occur with Le Fort I osteotomies done in multiple segments in conjunction with superior repositioning and transverse expansion. Significant palatal perforations definitely seem to compromise the already tenuous blood supply to the anterior maxilla. Suggestions are given regarding the prevention and treatment of this complication.

Moebius and Poland syndromes: a report of a case.

This report describes the dental treatment of a 45-month-old Native American Indian female with Moebius and Poland syndromes, two rare syndromes which can occur simultaneously.

Difficult tracheal extubation.

We describe a case of nasotracheal tube fixation with a screw. A second case is described in which a broken drill bit was found to impinge on the wall but not penetrate into the lumen of a nasotracheal tube. Possible sequelae of this complication include airway leak, aspiration, tube obstruction, and trauma from attempts at forceful extubation. We recommend the routine intraoperative testing for tracheal tube movement and routine fibreoptic bronchoscopy through the tube when blind surgical procedures occur in the vicinity of a tracheal tube.

Freeway space measurement using mandibular kinesiograph and EMG before and after TENS.

This investigation expands on a previous pilot study of the effects of TENS on the resting position of the mandible. The tendency is for an increase in freeway space, but the variability of results makes individual evaluation essential.

Carotid-cavernous sinus fistula following Le Fort I osteotomy.

A case report of a carotid-cavernous sinus fistula, a rare complication following orthognathic surgery, is presented. The anatomy and pathophysiology of the condition is discussed as they relate to the development of clinical signs and symptoms, and an attempt is made to explain this complication on the basis of a spectrum of possible internal carotid injuries following orthognathic surgery.

Vertical dimension and freeway space. A kinesiographic study.

A statistical correlation is found between the S-N/mandibular plane angle and clinical freeway space, but there was no correlation after TENS stimulation. The S-N/MP angle did not prove to be a reliable predictor of freeway space.

Reconstruction of the atrophic mandible.

Because atrophy of the jaws in edentulous patients is a major health problem, how best to reconstruct the atrophic mandible is a dilemma that frequently confronts the medical and dental professions. After loss of the natural dentition, the reduction of the residual ridges is progressive, irreversible, and cumulative. The cause and pathogenesis of mandibular atrophy is discussed. In the evaluation of a patient, the amount of residual bone at the symphysis should be measured on the lateral cephalometric radiograph as an aid to treatment planning. This measurement allows the degree of atrophy to be classified as minor, moderate, or severe. The current techniques to rehabilitate the edentulous mandible, including relative and absolute heightening techniques and implants, are reviewed with illustrative examples. A modification of a previous absolute heightening osteotomy technique utilizing pedicle bone flaps, is presented.