Biomechanical comparison of four different miniscrew types for skeletal anchorage in the mandibulo-maxillary area.

This study compared four miniscrew types for skeletal anchorage (Aarhus, FAMI, Dual Top and Spider) regarding their biomechanical properties contributing to primary stability. Insertion torque measurements and pull-out tests in axial (0 degrees ) as well as in the 20 degrees and 40 degrees direction were performed. Stiffness of the screw-bone construct was calculated from the load-displacement curve. Conic FAMI and Dual Top screws had higher insertion torques. Insertion torques were raised by drill-free insertion of FAMI and Dual Top screws. Statistically significant differences were found between the 4 screw types in pull-out tests. The highly significant differences between the four screws for peak load in the axial (0 degrees ) and 20 degrees direction were not apparent in 40 degrees angular loads. For the conical screws, peak load values increased in angular compared with axial load. The Dual Top screw achieved the highest values for peak load and stiffness. 12 Dual Top and 1 Spider screw heads fractured in the pull-out tests. A conical drill-free screw design achieves higher primary stability compared with cylindrical self-tapping screws. This effect was more obvious in insertion torque estimations rather than in pull-out tests. The Dual Top screws, although biomechanically superior to other screw types, were most prone to fractures.

Intraoperative navigation in the maxillofacial area based on 3D imaging obtained by a cone-beam device.

The aim of this study was to evaluate intraoperative navigation in the maxillofacial area based on three-dimensional imaging obtained by a cone-beam device. Digital volume tomograms (DVT) were obtained by the prototype of GALILEOS (Sirona Dental Systems Inc., Bensheim, Germany), a newly developed, compact size, cone-beam machine with a scan volume of 15 cm x 15 cm x 15 cm. Intraoperative navigation was performed in 12 patients in three selected indications. Target detection error expressing the accuracy of DVT navigation and registration performance of specially developed methods for image-to-patient registration was estimated. Target detection error was maximally 2 mm and depended on the registration method chosen. The automatic detection rate of the fiducial markers ranged between 0.64 and 0.32. The preoperatively defined treatment plan was fully accomplished in 11 out of 12 cases. A favourable surgical outcome was achievable in all cases. Intraoperative complications were not observed. Intraoperative navigation based on DVT imaging can be considered as a valuable alternative to CT-based procedures. Special characteristics of the cone-beam technique, in terms of contrast resolution and the limited field-of-view size of the devices, restrict the indication spectrum and create a demand for modifications of the usual registration methods.

Lateral femoral cutaneous nerve and iliac crest bone grafts--anatomical and clinical considerations.

This study investigates the topographical relationship of the lateral femoral cutaneous nerve (LFCN) to the anterior iliac crest and its clinical relevance in the context of bone graft harvesting. In the anatomical part of the study, LFCN was dissected and its course investigated in 34 human formalin-embalmed cadavers. In the clinical part, data of patients who underwent an iliac crest bone grafting procedure were collected and analysed. The obtained results were then compared with the results of other investigators published in the medical literature. From 34 nerves, the lateral branch of 1 LFCN (2.9%) crossed the anterosuperior iliac spine (ASIS) prominence at a distance less than 5mm superolaterally from the most anterior point of the spine. All other nerves ran below the inguinal ligament with an average distance of 14.6mm in the inferomedial direction from the spine. In 4 out of 298 patients (1.3%) who underwent harvesting of monocortical bone grafts from the inner table of the ilium, sensory disturbances in the dermatome of LFCN were observed. After a maximum period of 12 months all sensory disturbances resolved so that no case of permanent sensory impairment was recorded. The relatively low incidences of iatrogenic LFCN damage can be attributed to a standardized surgical concept which employs a lateral incision and layer by layer dissection to the periosteum/iliacal fascia level in order to identify the nerves potentially crossing the iliac crest above the ASIS.

Comparison of static and dynamic computer-assisted guidance methods in implantology.

The planning of dental implant position and its transfer to the operation site can be considered as one of the most important factors for the long-term success of implant-supported prosthetic and epithetic restorations. This study compares computer-assisted fabricated surgical templates as the static method with intro-operative image guided navigation as the dynamic method for transfer of three-dimensional pre-operative planning. For the static method, the systems Med3D, coDiagnostix/ gonyX, and SimPlant were used. For the dynamic method, the systems RoboDent und VectorVision2 were applied. A total of 746 implants were inserted between August 1999 and December 2005 in 206 patients. The static approach was used most frequently, accounting for 611 fixtures in 168 patients. The failure ratios within the first 6 months were 1.31% in the statically controlled insertion group compared to 2.96% in the dynamically controlled insertion group. Complications related to an incorrect position of the implants have not been observed so far in either group. All computer-assisted methods included in this study were successfully applied in a clinical setting after a certain start-up period. The indications for application of computer-assisted methods in implantology are currently given in difficult anatomical situations. Due to uncomplicated handling and low resource demands, the static template technique can be recommended as the method of choice for the majority of all cases falling into this category.

Image guided surgical navigation for removal of foreign bodies in the head and neck.

INTRODUCTION: The removal of foreign bodies in the head and neck area is often a surgical challenge due to a combination of difficult access and a close anatomical relationship of the foreign body to vital structures. Recent developments in computer-assisted surgery (CAS) have brought major improvements to the operating rooms for maxillofacial surgeons. The purpose of this paper is to report our experience in computer assisted removal of foreign bodies from the head and neck area, based on various clinical cases. PATIENTS: Computer assisted removal of foreign bodies from the head and neck area was performed in 11 patients. Three patients sustained gun shot wounds with remaining projectiles or fragments in the soft tissue. In six cases, objects related to a preceding surgical intervention were removed. Two patients presented with dislocated teeth in the facial or cervical soft tissues after 3rd molar surgery. METHOD: For surgical planning and intra-operative navigation, a computer based image guided surgery system (VectorVision(2), BrainLab) was used. RESULTS: In 10 of 11 cases the foreign bodies could be removed without major complications by a minimal invasive manner. More than 40 % of surgery time could be saved compared to similar interventions operated upon using conventional methods. CONCLUSION: In our opinion, the use of a computer based image guided surgical system is of great benefit when removing foreign bodies from the head and neck area. The minimally invasive access helps to prevent major complications such as injury to vital structures and allows a quicker operation.

The fronto-orbital osteotomy as plastic-reconstructive approach to the anterior and middle skull base.

INTRODUCTION: A combined extra-intracranial access for the operative exploration of tumours of the anterior and middle skull base is indicated when the tumour extends intracranially and simultaneously into the nasal cavity, the paranasal sinuses or the orbit. METHODS: Two standardized modifications of the fronto-orbital osteotomy, the fronto-orbito-nasal and the fronto-orbito-zygomatic osteotomy, allow safe removal of skull base tumours in these locations. In extensive skull base tumours, a modified bilateral fronto-orbital-zygomatic osteotomy can be used. RESULTS: Between February 1993 and July 2000 skull base tumours in 111 patients were resected using the presented methods. The most frequent tumour type was meningioma in 29 cases. Complications were encountered in 13 cases (11.7%). CONCLUSION: The advantages over other approaches are good extra- and intracranial overview and minimal cerebral trauma. Additional transfacial incisions are not usually necessary. Exact repositioning of the fronto-orbital segments leads to optimal aesthetic results.

Use of an image-guided navigation system in dental implant surgery in anatomically complex operation sites.

INTRODUCTION: Recent developments in computer assisted surgery have brought major improvements to maxillofacial surgery. Computer systems for intra-operative navigation have been introduced enabling the surgeon to locate the continually updated position of the instruments and the operation site on the patient's three-dimensional reconstructed image data set displayed on a monitor in the operating room. Complex surgical procedures can be performed according to the preoperative plan based on CT and/or MRI data minimizing surgical risks and optimizing clinical results. Nowadays computer-assisted-surgery has also proved effective in dental implantology. AIM: The objective of this study was to compare the accuracy of conventional and computer-assisted dental implantation planning and surgery. Analyzing our early experiences, we aimed to evaluate the benefit from utilising computer assisted surgery (CAS). PATIENTS: Five patients were treated with the aid of CAS, a total of 18 dental implants being placed. Only difficult operation sites, e.g. following bone augmentation or anatomically malformed jaws were included in this study. METHOD: An infra-red light based navigation system (Vector Vision 2, BrainLAB, Munich, Germany) including a three-dimensional planning approach for maxillofacial surgery was used. Placement of dental implants in the maxilla included direct visualization when drilling the implant socket according to the axis previously planned on radiographs and CT scans. RESULTS: In two cases the conventionally planned implant location had to be changed due to insufficient bone being available. With four implants, it proved possible to insert longer fixtures after the CAS system had evaluated all parameters of the surgical region. In one case a shorter implant was installed due to insufficient bone at the designated location. CONCLUSION: The use of an image-guided navigation system provides a valuable tool in implant dentistry and proved superior to conventional implant surgery especially in difficult anatomical regions.

MRI examination of the TMJ and functional results after conservative and surgical treatment of mandibular condyle fractures.

Thirty patients with healed condylar fractures were included in this study. Ten patients were conservatively treated while in 20 patients the fractures were treated surgically. All patients were assessed using: magnetic resonance imaging of both temporomandibular joints (TMJs) to evaluate the disc position and morphology; radiographs to evaluate the alignment of the bony fragments after consolidation; and clinical examination including the stomatognathic functional status and mechanical axiography. The study shows that anatomical reduction of a low, displaced or dislocated condylar fracture by surgical approach may be of benefit for the functional recovery of the TMJ.

Holographic face models as planning tool in maxillofacial surgery.

The holographic facial profile scan is a new technique for creation of high-resolution, three-dimensional, realistic facial computer models which can be used for surgical planning and documentation in maxillofacial surgery. First, a holographic image of the patient is recorded using a pulsed laser system. In a second step, called holographic tomography, the real image of the patient's hologram is reconstructed by means of a continuous-wave laser. By moving a screen through the real three-dimensional image, it is sliced into a series of two-dimensional projections which are captured with a digital camera. The slices containing the specific two-dimensional information are superimposed to a three-dimensional surface model using special software. The extremely short exposure time of 35 nanoseconds for taking a holographic image is separated from the time-consuming rendering process of the surface model; thus, the obtained models are not affected by the movements of the patient.

[Athletic injuries in mouth, jaw and facial surgery]. / Sportverletzungen in der Mund-, Kiefer- und Gesichtschirurgie.

Sport is a common cause of facial injuries. Depends on geographical distribution, 10% to 32% of all facial trauma cases are accounted to sporting activities according to the literature. In the following review article, sports-related facial injuries are classified based on their localization and on the principle of their treatment. Sports-specific mechanism underlying common injuries and state of the art concepts of diagnostics and surgical management, as currently practiced, are presented.

[Mouth guard protection for prevention of athletic injuries to teeth, mouth and jaw]. / Mundschutz zur Vorbeugung von sportbedingten Zahn-, Mund- und Kieferverletzungen.

Sport is well known as a common cause of dental and oral injuries. Sports-related injuries account for 13% to 39% of all trauma cases in this area. The knowledge about prevention of dental and oral injuries among hobby and professional athletes can be regarded as not satisfactory yet. Mouth guards are considered as one of the most effective means for injury prevention. However, no statements or recommendations regarding use of mouth guards in sports have been published in German language literature yet. The following review article describes several types of available mouth guards and discuss their advantages and disadvantages. Guidelines concerning indications and use of mouth guards are presented.

Intraoral molluscum contagiosum imitating a squamous-cell carcinoma in an immunocompetent person--case report and review of the literature.

A case of intraoral molluscum contagiosum involving the right distal alveolar bridge of an immunocompetent person is reported. A review of the literature, with only five previously published cases, revealed that involvement of the oral soft tissues is rare.

Diagnostic quality of multiplanar reformations obtained with a newly developed cone beam device for maxillofacial imaging.

OBJECTIVES: To compare the diagnostic quality of multiplanar reformations generated by a newly developed cone beam device with the diagnostic quality of multiplanar reformations obtained using a state of the art multidetector row CT scanner. METHODS: Digital volume tomograms (DVTs) were obtained with the prototype of GALILEOS (Sirona Dental Systems Inc., Bensheim, Germany), a newly developed compact-sized cone beam machine with a scan volume of 15 x 15 x 15 cm. CT scans were performed for comparison with two 16-detector row CT scanners. The study included 30 image pairs obtained from the same patients. The multiplanar reformations in axial, coronal and sagittal planes were subjectively assessed by 3 observers using a 1(excellent)-5(poor) scale on 35 weighted criteria including findings detection, image quality and visualization of several anatomical structures. RESULTS: There was no statistically significant difference between DVT and CT in cumulative values expressing the diagnostic quality of the reformations (P = 0.071). The interobserver agreement was better with CT than with DVT. Findings detection and the visualization of the majority of anatomical structures within the mandibulomaxillary area were ranked at the same level for DVT as with CT. CONCLUSIONS: The diagnostic quality of multiplanar reformations can be considered the same in both devices. Although sharpness, noise level and contrast resolution do not reach the level of CT, DVT images proved statistically not inferior for the detection of lesions which may be adequately depicted by both imaging modes.

[Chemodenervation with botulinumtoxin in masseteric hypertrophy]. / Die Chemodenervation mit Botulinumtoxin bei Masseterhypertrophie. Ergebnisse einer Behandlungsserie.

BACKGROUND: Masseteric hypertrophy is a unilateral or bilateral enlargement of the masseteric muscle of various aetiologies. The therapeutic options range from solely conservative measures, especially in functionally induced abnormalities, up to surgical ablation of the muscle. The presented study evaluates the application of botulinum toxin serotype A for the treatment of masseteric hypertrophy. PATIENTS AND METHODS: Between June 2000 and August 2004 seven patients with a unilateral and one patient with a bilateral manifestation of the condition were treated by an injection of botulinum toxin. RESULTS: A significant improvement of facial asymmetry caused by chemodenervation and following reduction of the hypertrophic muscle mass could be achieved in all cases. Complications during the injection, side effects, signs of intoxication, and therapy failure were not observed. CONCLUSION: The results of this treatment series show in agreement with the reports in the literature that the application of botulinum toxin can be currently considered as the therapy of choice in masseteric hypertrophy.

[Time saving and effective method of temporary intraoperative reposition in mandibular fractures. Realization with the FAMI screw]. / Zeitsparende und effektive Methode der temporären intraoperativen Reposition bei Unterkieferfrakturen. Realisierung durch Einsatz der FAMI-Schraube.

Open reduction and rigid fixation with maxillomandibular fixation at least intraoperatively is the method of choice for treatment of mandibular fractures. We report an effective method of internal temporary fixation which significantly facilitates fracture reduction and stabilization. The technique is used in combination with special FAMI screws and a monocortical miniplates system according to Champy, which eliminates in most cases the need for maxillomandibular fixation. Our results in 78 patients with mandibular fractures confirmed the reliability and the efficiency of the internal temporary fixation.