K.F. Moos

An Analysis of 2,067 cases of zygomatico-orbital fracture

A ten-year review of 2,067 cases of zygomatico-orbital fractures is presented. The age and sex distribution, anatomical types of fractures, associated maxillofacial and nonmaxillofacial trauma, and causes of the injuries are described. The majority of fractures were sustained by males and resulted from trauma inflicted in altercations. The most common associated facial fractures were mandibular; the most common associated nonmaxillofacial trauma was extremity fractures. Motorcycle accidents caused the most significant amount of associated trauma, followed by motor vehicle accidents in which no seat restraint was used by the victim. Treatment, when indicated, consisted of elevation via a temporal approach followed by fixation where necessary. The fixation methods used are presented and discussed.

A vision-based three-dimensional capture system for maxillofacial assessment and surgical planning

We describe a vision-based three-dimensional facial data capture system designed for the planning of maxillofacial operations. We describe the system requirements and outline the methods used to develop a complete three-dimensional facial capture system. Our approach is based upon imaging the face using two stereo-pair sets of cameras. Scale-space-based stereo-matching is then used to recover correspondences between each of the captured stereo-pairs. Photogrammetric routines based on adjustment of bundles are used off-line to calibrate the system by imaging a single object that references all cameras to the same co-ordinate frame. This calibration scheme allows us to convert stereo correspondences to world points for each pair of cameras without the need for any subsequent fusion of data. Initial results show that we are able to capture key facial landmarks to within 0.5 mm.

The use of Silastic as an Orbital Implant for Reconstruction of Orbital Wall Defects - Review of 311 Cases Treated Over 20 Years

PURPOSE A retrospective review of silicone rubber (Silastic; Dow Corning, Midland, MI) implants placed in orbits was undertaken. These implants were used to reconstruct defects in the orbital floor and/or walls secondary to trauma, or those created during malar or orbital osteotomies. The purpose of the study was to determine the incidence of removal of these implants from the surgical site. MATERIALS AND METHODS The records of 311 patients treated over a 20-year period were reviewed. Of these, 302 had received silastic implants secondary to trauma. RESULTS Forty-one patients (13%) had their implant removed at a second operation. The reasons for removal included infection, migration of the implant, worsening eye sign such as diplopia, and others. CONCLUSION Because there was a clinically significant rate of removal of this material, consideration should be given to the use of other available materials.

How accurate is model planning for orthognathic surgery

The purpose of this study was to evaluate the accuracy of model surgery prediction after orthognathic surgery and to identify possible errors associated with the prediction process. The study included 46 patients who had undergone orthognathic surgical procedures; 22 in Group A who had had a Le Fort I osteotomy; and 24 in Group B who had had a Le Fort I osteotomy and mandibular setback surgery. The immediate postoperative and preoperative lateral cephalograms were analysed to calculate surgical changes; these were compared with those obtained from model surgery prediction and a statistical analysis was undertaken. The maxilla was more under-advanced and over-impacted anteriorly than predicted by model surgery. The amount of mandibular setback was more than that predicted by model surgery. None of the differences between prediction planning and actual surgical changes was statistically significant at p<0.05. Inaccuracy with the face bow recording, the intermediate wafer, and auto-rotation of the mandible in the supine or anaesthetized patient would appear to be the principal reasons for errors. Inaccuracies are associated with the transfer of prediction planning to model surgery planning and prediction, which should be eliminated to improve the accuracy and predictability of orthognathic surgery.

Face bow and articulator for planning orthognathic surgery: 1 face bow

Orthognathic surgery that involves movement of the maxilla relative to the skull is usually planned using casts mounted on an articulator. Accurate positioning of the maxilla relative to the skull is essential for reliable planning, but current methods of mounting casts on articulators are inaccurate and unreliable. We propose that the casts should be mounted using the relation between the horizontal plane and the resting head position to define the position of the skull. A photographic study of 10 subjects confirmed the reproducibility of the head position and its relation to the horizontal plane. A face bow incorporating a circular spirit level was used to transfer the relation between the horizontal and the maxillary dentition to a semiadjustable articulator. The angle between the horizontal and maxillary occlusal planes was measured from six lateral cephalograms and compared with those of casts mounted on a semiadjustable articulator using a face bow with either an orbital pointer or a spirit level. The face bow with a spirit level produced considerably more accurate results.

Infraorbital nerve function following treatment of orbitozygomatic complex fractures. A multitest approach.

Sensory disturbance following orbitozygomatic complex fractures was studied in 65 patients in relation to type of fracture and method of treatment. The fracture-type-dependent treatments were: no surgical intervention (n = 20), closed reduction with or without wire fixation (n = 17), open reduction with miniplate fixation (n = 15) and/or reconstruction of the orbital floor (n = 13). Several methods were applied to assess sensory function, on average 6.3 months after treatment, i.e. the patients report and tests regarding touch, two methods of two-point discrimination, and cold, all applied on the cheek and upper lip. The various examinations indicated that, on average, the long-term sensory disturbance was most pronounced and severe in patients who underwent closed reduction without miniplate fixation. As the sensory disturbance of patients with open reduction and miniplate fixation approached the base-line level of patients for whom surgical intervention was not indicated, open reduction with miniplate fixation can be recommended as treatment for frontozygomatic suture fractures. The degree of sensory disturbance of patients who underwent orbital floor reconstruction was intermediate compared to patients with closed and open reduction respectively.

Influence of close resection margins on local recurrence and disease-specific survival in oral and oropharyngeal carcinoma

There is a lack of consistency among published reports in the definition of what constitutes close resection margins (1-5mm) in the surgical treatment of oral and oropharyngeal squamous cell carcinoma (SCC). Our aim was to define what would constitute close resection margins in predicting local recurrence and disease-specific survival. The study comprised 192 previously untreated patients with oral and oropharyngeal SCC who were recruited at the Southern General Hospital, Glasgow, from 2001 to 2007 with a minimum follow-up of 2 years. Resection was the primary treatment and the surgical margins were recorded for all patients. Statistical analyses were aided by the Statistical Package for the Social Sciences, version 15.0, and MedCalc software. The status of the surgical margins was evaluated using a receiver operating characteristic (ROC) curve to define the cut-off point. Coxs proportional hazard model was used to establish predictive factors for local recurrence and disease-specific survival. Of 192 patients, 23 (12%) had involved margins (<1.0mm), 107 (56%) had close margins (1.0-2.0mm (16.1%); 2.1-3.0mm (12%); 3.1-4.0mm (10.4%); 4.1-5.0mm (17.2%), and 62 (32.3%) had clear margins (>5mm). No predictive cut-off point was found that related close surgical margins to local recurrence. However, there was a significant adverse association between surgical margins ≤1.6mm and disease-specific survival. In recommending postoperative adjuvant treatment for oral and oropharyngeal SCC, we suggest that surgical margins within 2mm should be considered as the cut-off. However, other clinical and pathological prognostic factors should also be taken into consideration when recommending further treatment.

Extra-oral endosseous craniofacial implants: current status and future developments

The published experience of extra-oral endosseous craniofacial implants (EOECIs) is reviewed. The definition of osseointegration, concept of success, the relative merit of one- or two-stage implant placement, EOECI design and control of peri-abutment skin infection are discussed. A plea is made for more consistent and objective reading of clinical experience of this technique.

Information on infraorbital nerve damage from multitesting of sensory function

Sensory disturbance following orbitozygomatic complex fractures was studied in 65 patients from 4 treatment groups which represented potentially varying degrees of sensory disturbance. The fracture-type-dependent treatments were: no surgical intervention (n = 20), closed reduction with or without wire fixation (n = 17), open reduction with miniplate fixation (n = 15) and/or reconstruction of the orbital floor (n = 13). In order to assess the sensory function of different classes of afferent fibres, several methods of sensory testing were applied. On average 6.3 months after treatment, the patients report was obtained, and tests regarding touch, two methods of two-point discrimination, and cold were applied on the cheek and upper lip. The degree of sensory disturbance was method-dependent. In patients who underwent closed reduction, pronounced levels of positive correlation occurred between results from different tests or from both test sites. The levels of these correlations were, in general, low for all other treatments. These findings suggest that afferent fibres of both large and small diameter tended to be permanently damaged in the patient group with closed reduction. In contrast, the types of sensory afferent fibres that were involved in the trauma and/or their recovery were highly variable within patients and sites for all other treatment groups.

Assessment of chin surgery by a coordinate free method

A quantitative description of the changes and stability after genioplasty in a cross-sectional sample of 19 patients who had advancement genioplasty is presented. Euclidean distance matrix analysis (EDMA) of five cephalometric landmarks was used to assess these changes. During the first 6 months after surgery, bone deposition occurred at B point and pogonion, with bone resorption at the superior and posteroinferior aspects of the advanced segment. The genial segment rotated slightly anticlockwise. The authors believe this to be due to the action of the mentalis muscles. The stability of the advanced segment was excellent when assessed 1 year after surgery. The Euclidean distance matrix method can be used to assess shape changes and does not require cephalographic superimposition. It can also distinguish repositioning from remodelling and the changes of genioplasty from those of concomitant orthognathic surgery.