Removal of a pellet from the left orbital cavity by image-guided endoscopic navigation.

In the cranio-maxillofacial field, computer-aided surgery based on computed tomography data is becoming increasingly important. Complex surgical procedures can be performed utilizing preoperative imaging to provide real-time localization of surgical instruments in the surgical field. Image-data-based navigation plays an ever-increasing role in cases of minimal invasive surgery. The case is presented here of a 58-year-old male patient referred after a hunting accident with a pellet in the left orbit. After transferring the preoperatively acquired computed tomography data to a commercially available navigation system, the bullet was removed through the original wound canal using an intraoperatively calibrated high-resolution endoscope.

Cardiac metastasis after squamous cell carcinoma of the oral cavity: case report.

A 58-year-old woman presented with respiratory problems 6 months after she had had a squamous cell carcinoma in the oral cavity resected. We found on computed tomography a large lesion in the cardiac muscle. There were no abnormalities in the electrocardiogram. The patient died 7 days later and necropsy confirmed a solitary metastasis in the myocardium that originated from a squamous cell carcinoma of the mouth.

Exploring the molecular basis for mechanosensation, signal transduction, and cytoskeletal remodeling.

Living cells respond to mechanical stimulation in a variety of ways that affect nearly every aspect of their function. Such responses can range from changes in cell morphology to activation of signaling cascades and changes in cell phenotype. Although the biochemical signaling pathways activated by mechanical stimulus have been extensively studied, little is known of the basic mechanisms by which mechanical force is transduced into a biochemical signal, or how the cell changes its behavior or properties in response to external or internal stresses. One hypothesis is that forces transmitted via individual proteins either at the site of cell adhesion to its surroundings or within the stress-bearing members of the cytoskeleton cause conformational changes that alter their binding affinity to other intracellular molecules. This altered equilibrium state can subsequently either initiate a biochemical signaling cascade or produce more immediate and local structural changes. To understand the phenomena related to mechanotransduction, the mechanics and chemistry of single molecules that form the signal transduction pathways must be examined. This paper presents a range of case studies that seek to explore the molecular basis of mechanical signal sensation and transduction, with particular attention to their macroscopic manifestation in the cell properties, e.g. in focal adhesion remodeling due to local application of force or changes in cytoskeletal rheology and remodeling due to cellular deformation.

Scanning electron microscopical analysis of laser-treated titanium implant surfaces--a comparative study.

Design and surface qualities of titanium implants are of vital importance for long-term stability following implantation. Four different implant surfaces treated individually were analyzed with special attention focused on laser surface treatment. Surfaces with machine roughness, titanium spray coating, treated by aluminum oxide and treated by laser were examined individually. Evaluation of the surface was carried out by electron microscope examination and mechanical profilometry. The EDS analysis determined the degree of contamination of the implant surface. Electron microscope examination showed that the titanium plasma spray as well as the laser-treated implants have optimum surface qualities: a secondary and tertiary structure with micro-roughness of 10 mm and roughness ranging from 0.5 to 4 mm. The least contamination was found for machine rough surfaces as well as those treated by laser. The other implants showed contamination corresponding to the method of surface treatment. In summary the optimal surface structure with the least contamination was found for the laser-treated titanium surface. Similar surface purity was found for the machine rough surfaces. An optimal structure was also achieved by the titanium plasma spray method, however, at the cost of surface purity.

Periodontal disease in patients with cleft palate and patients with unilateral and bilateral clefts of lip, palate, and alveolus.

BACKGROUND: Long-term health of the stomatognathic system, as well as esthetics, is the therapeutic goal in patients with facial clefts. The aim of this study was to analyze the periodontal situation of patients with cleft palate (CP) and cleft lip, palate, and alveolus (CLPA) to elicit the differing degrees and localization of periodontal disease. METHODS: In 30 patients with unilateral cleft lip, palate, and alveolus (UCLPA), 30 patients with cleft palate (CP), and 20 patients with bilateral cleft lip, palate, and alveolus (BCLPA), the gingival situation was identified and classified according to the sulcus bleeding index (SBI). Periodontal attachment loss and pathological loosening of teeth were noted for identification of periodontal lesions. The state of oral hygiene was recorded by the approximal plaque index (API). RESULTS: In general, poor oral hygiene was found in all patients. The SBI showed a high incidence of gingivitis in patients with cleft lip, palate, and alveolus. Patients with cleft palate had a minor extent of sulcus bleeding. Periodontal disease was found to a similar extent to that in the general population in patients with cleft palate, whereas patients with cleft lip, palate, and alveolus had a predisposition to deep periodontal destruction of teeth adjacent to the cleft. The registration of pathological loosening of teeth, a result of attachment loss, corresponded to the degree of periodontal disease shown by the attachment loss. CONCLUSIONS: A critical periodontal situation was found in patients with unilateral and bilateral cleft lip, palate, and alveolus, ultimately leading to tooth loss in the front tooth region. In contrast, patients with cleft palate exhibited periodontal situations similar to that found in the general population with additional damage, which may be attributed to orthodontic treatment.

18F-FDG PET: early postoperative period of oro-maxillo-facial flaps.

AIM: We addressed the feasibility of FDG-PET to differentiate between viability and non-viability in the immediate postoperative assessment of flaps (autologous microvascular anastomosed pedicled flaps) in oro-maxillo-facial surgery. METHODS: 3-7 days after surgery, FDG-PET was done in 38 patients who had received flaps for re-construction of the mandible after partial resection. The studies were done on a dedicated full ring PET-scanner (ECAT EXACT HR+, Siemens/CTI). Acquisition started between 60 and 80 min post injection. The findings of the soft tissue component of the flaps were grouped using a three point scale: (I) no defect, (II) small defects, (III) one large defect. The results of PET were compared with the clinical course for at least 3 months. RESULTS: "No defect" on the FDG-PET study identified vi-ability of the flap and predicted normal clinical follow-up (22/38 patients). "Small defects" visualized areas of decreased perfusion and decreased glucose metabolism indicating risk of non-viability (13/38 patients); adapt-ing the postsurgical management led to delayed but uncomplicated healing of the flaps in these patients. "One large defect" demonstrated early necrosis of the flap (3/38 patients). After removal and replacement of this necrotic portion of the flap the second FDG-PET scan of these 3 patients demonstrated the uncomplicated post-operative healing. CONCLUSION: FDG-PET facilitated the assessment of viability and non viability of flaps in the immediate postsurgical period, and demonstrated the usefulness of FDG-PET for postoperative care and prognosis.

Vertical alveolar ridge distraction with prosthetic treatable distractors: a clinical investigation.

Alveolar ridge distraction is a recent and promising technique for ridge augmentation. Since 1997, a new distraction system incorporating a distraction implant has been in use. It can be used for alveolar ridge distraction and is not removed from the alveolar ridge. Upon completion of the distraction, it remains in the alveolar process for later prosthetic treatment. Thirty-five patients were treated with distraction implants for the correction of alveolar ridge deficiency. In 10 patients with atrophy of the mandible or maxilla, 16 patients with severe defects of the alveolar process after trauma, and 9 patients with localized alveolar ridge defects after single tooth loss, alveolar ridge distraction was carried out with the aid of 62 distraction implants. The distraction implants were loaded by prosthetic superstructures 4 to 6 months after distraction. A clinical and radiologic follow-up was carried out. Periotest values were examined, and peri-implant bleeding and probing depth were registered prior to prosthetic treatment and 3, 6, and 9 months after implant loading. In 29 patients, distraction was carried out without complications or problems. Two distraction implants were lost. In 2 patients distraction was discontinued because of ankylosis of the distraction segment. In 1 patient the alveolar ridge was overcorrected, and another patient experienced a persisting hypoesthesia of the lip. For 5% of the implants, pathologic probing depth of more than 3 mm and sulcus bleeding were registered prior to prosthetic treatment. These observations decreased during the next 9 months. Periotest values were normal before the start of prosthetic treatment. There was a decrease in the Periotest values, thus an increase in implant stability, during the following 9 months. It was concluded that alveolar ridge distraction using distraction implants can be a successful technique for alveolar ridge augmentation with a low rate of complication. Acceptable esthetic and functional results can be achieved by this atraumatic technique of surgery and distraction.

Three-dimensional craniofacial surgery: transfer from a three-dimensional model (Endoplan) to clinical surgery: a new technique (Graz).

A new technique of individual, three-dimensional (3-D) planning and transferring this to craniofacial operations is reported. The combination of an individual model of the skull of the patient with a transfer device enables planning of real 3-D surgery. The surgical technique is demonstrated in a case with an asymmetrical midface and mandible after ankylosis of the TMJ in childhood.

MR imaging of the TMJ. MR diagnosis and intraoperative findings.

Magnetic resonance imaging provides the possibility of a non-invasive method for the investigation of the soft tissues of the temporomandibular joint (TMJ). Between March 1991 and August 1992 we performed static and dynamic magnetic resonance images (MRI) on 47 TMJs of 37 symptomatic patients using a MR-tomograph with a 6.5 cm surface coil. MR diagnosis could be verified in 15 joints at operation and in 3 cases by arthrotomography. Disc position was confirmed in 80%, perforations were missed in 2 out of 3 cases and two more perforations became obvious during operation. One patient refused MR examination, in 2 cases MRI had to be abandoned because of the patient's claustrophobia. In our work we wanted to show that MRI is a reliable tool to determine disc position, disc shape and disc behaviour during motion. Detection of perforations is still the domain of arthrography.

Reestablishment of sensitivity in the latissimus dorsi transplant through anastomosis of the thoracodorsal nerve with sensitive nerves.

The question as to whether anastomosis of sensory nerves is recommended for free transplants of the myocutaneous latissimus dorsi flap, reanastomosed by microvascular surgery, remains a controversial issue. In this study, a microsurgical nerve anastomosis was performed to sensitize a latissimus dorsi transplant. To determine sensation in the transplanted tissue, six patients were examined clinically. All patients had free transplants of latissimus dorsi flaps reanastomosed by microvascular surgery after tumor resection in the oral cavity. An anastomosis of the sensible auricular magnus nerve with the motor thoracodorsalis nerve was performed. Resulting sensation was determined clinically by testing for pain, temperature, pressure, two-point discrimination, and vibration. All patients showed sensation in the latissimus dorsi flap beginning between the third and the fifth month postoperatively. Therefore, resensitization of a large and voluminous myocutaneous latissimus dorsi flap should be attempted by a nerve anastomosis in this transplant.

Indications and limitations of three-dimensional models in cranio-maxillofacial surgery.

Anatomical, life-like, three-dimensional (3D) models have a definite place in cranio-maxillofacial surgery. Our experience with 541 computer tomography (CT)-based 3D models employed in aiding corrective surgery of tumours, dysgnathia, traumatology, alveolar atrophy, congenital malformation and asymmetrical malformations in our department is discussed. From July 1988 to February 1997, 3D models of 346 patients were used. Most of these were produced at our clinic. The indications, advantages and limitations of 3D-models were analysed retrospectively. In the case of congenital malformations (n = 60), models facilitated precise diagnosis of the skeletal deformity. Simulation surgery allowed prediction and solution of intraoperative problems prior to the actual patient operation. Size, shape and localization of defects caused by trauma (n = 64), osteoradionecrosis (n = 17) or osteomyelitis (n = 2) determined the choice of transplant donor site. In patients suffering from dysgnathia (n = 144), 3D models enabled exact positioning of the jaws. Precise planning could only be accomplished with the help of 3D models, especially for asymmetrical malformations (n = 12). In cases of severe atrophy of the alveolar crest (n = 45), exact measurement of the bone was possible and facilitated the decision as to whether dental implants, bone transplants or a combination of these were indicated. The positioning of transplants and implants was carried out in the ideal relation to the opposite jaw. In tumour patients (n = 186), it is not always possible to identify the tumour borders precisely on the CT scan or 3D model. Therefore, the defect was assumed to be bigger, a longer bridging plate constructed and this measurement corrected according to the intraoperative situation. The advantage of the 3D models consisted of an accurate representation of anatomical structures, bone or soft tissue. This allows precise preoperative diagnosis, operation planning and model operations. Due to this, the correct approach as well as operation technique could be chosen, outcomes of constant high quality were achieved, and there was a reduction in operation time.

Distraction implants: a new operative technique for alveolar ridge augmentation.

In the past alveolar ridge augmentation was mainly based on autologous or allogenic bone transplants. Since 1996 alveolar ridge distraction has enabled local osseous build-up without bone transplantation. The 'distraction implant', uniting qualities of a distraction apparatus with those of a dental implant, has been in use for three years at the Department of Oral and Maxillofacial Surgery of Graz University. Its application in patients with alveolar ridge atrophy and other defects is demonstrated and the first results are presented in this study. Three patients with severe alveolar ridge atrophy of the edentulous mandible, three with extensive alveolar ridge defects and three with local alveolar defects following traumatic loss of a single tooth were treated with distraction implants. Segmental osteotomy was carried out in all patients and one or two distraction implants were positioned. Following this alveolar ridge distraction was carried out. In seven cases there were no complications, whereas in one patient distraction was discontinued, and altogether two distraction implants had to be removed. All complications were treated by conventional operative techniques. Fifteen of 17 distraction implants were loaded successfully. Alveolar ridge distraction by means of distraction implants is an adequate method of alveolar ridge augmentation resulting in improved implant sites and gingival conditions. The segment for distraction should not be smaller than an upper central incisor. The implants can be used for prosthetic treatment, but long-term results are still not finalised.

Analysis of midface asymmetry in patients with cleft lip, alveolus and palate at the age of 3 months using 3D-COSMOS measuring system.

INTRODUCTION: Patients suffering from unilateral cleft lip, alveolus and palate exhibit a varying degree of asymmetry of the midface. Evaluation of this asymmetry can be carried out by means of 3D-CT, or a laser surface scanner. MATERIAL AND METHODS: In this paper, 3D-CT-scan data of 21 patients with unilateral clefts of lip, alveolus and palate were analysed using three-dimensional models. Evaluations of the 3D-models were carried out with the computer-aided 3D-operation simulator 3D-Cosmos. RESULTS: Asymmetry was found in the orbital, nasal and maxillary regions. The infraorbital rims were displaced craniocaudally and horizontally as well as laterally of the cleft-sided piriform aperture. This asymmetry corresponded to a dislocation of the maxillary segment on the cleft side. A deficit in volume was not reliably found.

Navigational precision of drilling tools preventing damage to the mandibular canal.

PURPOSE: The use of CT-based intraoperative navigation has greatly improved surgical control in many specialities. In this study the precision of the SMN system (Zeiss, Oberkochen, Germany) for navigated drilling before implant insertion is evaluated. MATERIAL AND METHOD: One hundred test drillings were carried out on 10 standardized acrylic lower jaw models with the aid of the navigation system after CT scanning. The CT scans were taken using a slice thickness of 1 mm. Then the CT data were transferred to the workstation of the SMN system and referentiation with the help of reference points (fiducials) of the mandibular models for superposition of the acrylic and the CT models were carried out. Referentiation of the model and the drilling were performed by a drilling tool. The limit of drilling was the upper border of the mandibular canal. The aim was to come as near as possible without perforation of the canal roof. RESULTS: An average drilling depth of 6.23 mm and a mean distance to the mandibular canal of 0.14 mm (s=0.05) was found. In 11 cases the upper border of the canal was perforated. The average penetration of the mandibular canal measured 0.19 mm. Eighty-nine drill holes were accomplished without perforation. The average distance to the alveolar canal measured 0.13 mm. CONCLUSION: A high precision of CT-based navigation for controlled drilling of mandibles for dental implants was seen.

Histologic results of neuronal anastomosis of the microvascular latissimus dorsi transplant.

Latissimus dorsi transplants have little neuronal regenerative capacity without neuronal anastomosis. Histologic differences between transplants with and without neuronal anastomosis and two distinct types of neurotization are highlighted in this study. Eighteen patients after tumor resection and defect coverage with a latissimus dorsi transplant were examined preoperatively and postoperatively by means of a biopsy for histologic examination. The number of fascicles, degree of scarring, myelinization, and fibrosis were examined. All patients had a mean of 11.8 fascicles preoperatively. Patients without neuronal anastomosis showed an average of 5.0 fascicles, patients with nerve anastomosis to the cutaneous branches of the intercostal nerve showed an average of 6.2 fascicles, and patients with anastomosis to the thoracodorsalis nerve showed an average of 9.2 fascicles postoperatively. In cases of nerve anastomosis, a lesser degree of fibrosis was found, together with good myelinization. Neuronal reanastomosis led to more vital neuronal structures in the postoperative histologic specimen. The highest density of fascicles was found in the case of the well-vascularized thoracodorsalis nerve.

The Graz implant supported pendulum, a technical note.

A new, immediately loadable palatal implant with rotational stability and an implant-supported pendulum for patients with dental class II dysgnathia and dental crowding is presented. In seven cases, the treatment goal of distalization of all upper molars without extraction of a single tooth was achieved within 8 months.

Computer assisted tumour resection of the skull base: case report.

This case report demonstrates computer assisted resection of a skull base tumour after combined chemotherapy and irradiation, in a 40-year-old man with a squamous cell carcinoma of maxilla, zygoma, orbit and skull base. The resection of the skull base was performed with computer assistance after conventional resection of the maxilla, midface, exenteration of the orbit and lymph node dissection. Following combined chemotherapy and irradiation, the original, pretherapeutic tumour extent was marked on the new, presurgical CT scan enabling resection of the skull base with the use of a navigation microscope. Thus planned resection from the presurgical CT could be transposed intraoperatively using the navigation system, and the skull base could be resected with precision.

Interstitial radiotherapy with Ir-192 as a palliative treatment modality in head and neck cancer.

In selected patients with advanced head and neck cancer interstitial radiotherapy with Ir-192 can be used as a palliative treatment. Using two cases as examples, we report on our experiences with 19 patients.

Combination of microsurgical tissue reconstruction with osteointegrated dental implants. Presentation of a technique.

A technique is presented in which resected mandibles are restored with a combination of microsurgically revascularized jejunal grafts and bone grafts. The bone grafts served as a recipient for Branemark implants. The preliminary results showed that the jejunal mucosa tolerates the implants well and the masticatory function was adequately restored in the patients discussed.