[Computer-aided reconstruction of the facial skeleton : Planning and implementation in clinical routine]. / Computerassistierte Gesichtsschädelrekonstruktion : Planung und Umsetzung in der klinischen Routine.

In computer-aided reconstruction of the facial skeleton, a workflow has been established involving the following steps: > diagnosis → planning and simulation → surgical procedure → validation and quality control <. In addition to clinical findings, the focus of diagnosis is on three-dimensional (3D) imaging, particularly computed tomography. Planning and simulation involves creation of a virtual model of the desired surgical outcome using special planning software. The accuracy of implant fit can be virtually verified before surgery. 3D models and virtual reconstructions can be used for manufacturing patient-specific implants. During the surgical procedure, planning must be transferred to the surgical site as accurately as possible. A number of techniques are available for this purpose, e. g., closed reduction, open reduction with the placement of anatomically preformed or patient-specific implants in combination with surgical guides, and the additional use of navigation. Validation and quality control require postprocedural 3D imaging. After reconstructions of the midface, 3D imaging should be performed even before surgery is completed. Malpositions can thus be directly corrected and unnecessary open reconstructions avoided. Mobile 3D c-arms are particularly useful for intraoperative 3D imaging. Whereas intraoperative imaging makes postoperative imaging after midface reconstruction unnecessary in many cases, postoperative 3D imaging in addition to intraoperative imaging may still be recommended after complex reconstructions of the facial skeleton.

Determinants of Microscale pH in In Situ-Grown Dental Biofilms.

Dental biofilm pH is the most important determinant of virulence for the development of caries lesions. Confocal microscopy-based pH ratiometry allows monitoring biofilm pH with high spatial resolution. Experiments performed on simplified biofilm models under static conditions identified steep pH gradients as well as localized acidogenic foci that promote enamel demineralization. The present work used pH ratiometry to perform a comprehensive analysis of the effect of whole saliva flow on the microscale pH in complex, in situ-grown 48-h and 96-h biofilms (n = 54) from 9 healthy participants. pH was monitored in 12 areas at the biofilm bottom and top, and saliva flow with film thicknesses corresponding to those in the oral cavity was provided by an additively manufactured microfluidic flow cell. Biofilm pH was correlated to the bacterial composition, as determined by 16S rRNA gene sequencing. Biofilm acidogenicity varied considerably between participants and individual biofilms but also between different areas inside one biofilm, with pH gradients of up to 2 units. pH drops were more pronounced in 96-h than in 48-h biofilms (P = 0.0121) and virtually unaffected by unstimulated saliva flow (0.8 mm/min). Stimulated flow (8 mm/min) raised average biofilm pH to near-neutral values but it did not equilibrate vertical and horizontal pH gradients in the biofilms. pH was significantly lower at the biofilm base than at the top (P < 0.0001) and lower downstream than upstream (P = 0.0046), due to an accumulation of acids along the flow path. pH drops were positively correlated with biofilm thickness and negatively with the thickness of the saliva film covering the biofilm. Bacterial community composition was significantly different between biofilms with strong and weak pH responses but not their species richness. The present experimental study demonstrates that stimulated saliva flow, saliva film thickness, biofilm age, biofilm thickness, and bacterial composition are important modulators of microscale pH in dental biofilms.

[The hybrid operating room. Home of high-end intraoperative imaging]. / Der Hybridoperationssaal. Zentrum intraoperativer Bildgebung.

A hybrid operating room must serve the medical needs of different highly specialized disciplines. It integrates interventional techniques for cardiovascular procedures and allows operations in the field of orthopaedic surgery, neurosurgery and maxillofacial surgery. The integration of all steps such as planning, documentation and the procedure itself saves time and precious resources. The best available imaging devices and user interfaces reduce the need for extensive personnel in the OR and facilitate new minimally invasive procedures. The immediate possibility of postoperative control images in CT-like quality enables the surgeon to react to problems during the same procedure without the need for later revision.

Clinical Accuracy of 3D-Planned Maxillary Positioning Using CAD/CAM-Generated Splints in Combination With Temporary Mandibular Fixation in Bimaxillary Orthognathic Surgery.

STUDY DESIGN: The aim of this study was to evaluate the accuracy of 3-dimensional (3D)-planned maxillary positioning by using computer-assisted design (CAD)/computer-assisted manufacturing (CAM) splints combined with temporary mandibular fixation in bimaxillary orthognathic surgery. In orthognathic surgery, customized splints work sufficiently well to transfer preoperative planning into the operation site for transverse und sagittal positioning of the maxilla. The vertical positioning is more difficult due to the non-fixed mandibular reference. Therefore, the combined use of CAD/CAM splints and temporary mandibular fixation to the zygomatic region was applied for transferring the 3D-planned maxillary position into the operation site from 2012 until 2015 in our hospital. OBJECTIVE: In addition to the general accuracy, the precision should therefore be checked especially in the vertical plane compared to axial and sagittal plane. METHODS: In this retrospective study, we calculated the deviation of 5 occlusal landmarks of the maxilla in 35 consecutive patients by fusing preoperative 3D planning images and postoperative computed tomography scans after bimaxillary surgery. RESULTS: The overall median deviation of maxillary positioning between plan and surgical result was 0.99 mm. The accuracy of left-right positioning was median 0.96 mm. Anterior-posterior positioning of the maxilla showed a median accuracy of 0.94 mm. Just slightly higher values were determined for the upward-downward positioning (median 1.06 mm). CONCLUSIONS: This demonstrates the predictability of maxillary positioning by using CAD/CAM splints in combination with temporary mandibular fixation in all 3 axes.

Endoscopy-assisted open treatment of condylar fractures of the mandible: extraoral vs intraoral approach.

By using an endoscopy assisted extraoral and transoral approach for open reduction of condylar mandible fractures with limited incisions, the risk of facial nerve damage and extensive visible scars can be reduced. The endoscopy-assisted treatment of 17 consecutive patients with fractures of the condyle was performed from April 1998 to December 1999. Of the 17 patients, 13 presented with additional mandibular fractures. Nine of the 17 patients were treated by a submandibular approach and eight by a transoral approach. Adequate anatomic reduction was achieved by the submandibular and transoral approach using an endoscopy-assisted technique. The transoral approach proved to be a reliable surgical approach for fractures of the mandibular condyle, even when dislocation with lateral override was present. In four patients, angulated drills and screwdrivers facilitated the transoral treatment of condylar fractures. Transbuccal stab incisions and the use of trochars were not needed in these four patients. The extraoral approach was indicated for severely dislocated fractures such as fractures with medial override or comminution.

Repair of complex orbital fractures: technical problems, state-of-the-art solutions and future perspectives.

Within the wide range of severity of orbital fractures, the small group of complex fractures causes most of the sequelae. Therefore identification of severe injuries and adequate treatment is of major importance. The introduction of craniofacial techniques made possible a wide exposure of even large orbital wall defects and their reconstruction by grafts. In spite of significant progresses, repair of complex orbital wall defects remains a difficult surgical problem even for the experienced. This paper outlines the specific technical problems concerning surgical anatomy, exposure and defect reconstruction of this type of injuries. A number of new developments providing interesting future perspectives for orbital wall reconstruction such as intraoperative navigation, endoscopic techniques and new materials are discussed.

Computer-assisted therapy in orbital and mid-facial reconstructions.

BACKGROUND: Management of orbital and mid-facial fractures requires a thorough ophthalmic evaluation and precise imaging. A principle goal of therapy is to anatomically reduce fracture segments and to restore a normal orbital volume as soon as possible. Diagnostic advances such as new surgical and imaging techniques have dramatically improved both the functional and aesthetic outcome of reconstructions. METHODS: Orbital reconstruction is performed using computer-assisted navigation. This technique makes preoperative simulation by mirroring the unaffected side onto the affected side. RESULTS: Results from computer-assisted navigation application to both primary and secondary orbital and mid-facial reconstruction are shown. CONCLUSION: Navigation technique it offers significant advantages in both primary and secondary reconstructions. Navigation facilitates reconstruction in unilateral defects through mirroring techniques, and in bilateral defects by importing virtual models from standard CT datasets improving the software tool to fulfil the need for maxillofacial surgery reconstruction.

[Computer-assisted insertion of zygomatic implants (Brånemark system) after extensive tumor surgery]. / Rechnergestützte Insertion von Zygomatikumimplantaten (Brånemark-System) nach ablativer Tumorchirurgie.

Installation of fixtures for prosthetic reconstruction of the upper jaw in patients with extensive bone and soft tissue defects is still a challenge. The new fixture developed by Brånemark System achieves immediate prosthetic reconstruction by anchoring implants in the zygomatic bone to offer sufficient support without bone grafts. The dimension of these zygomatic fixtures and the complex anatomy due to previous surgical procedures demand specific treatment for a precise and safe insertion of the implants. On the basis of an axial spiral CT data set, the STN navigation system (Stryker-Leibinger/Zeiss) was used for preoperative planning and intraoperative control of the insertion of zygomatic fixtures after subtotal maxillectomy. Computer-assisted insertion of zygomatic fixtures was successfully completed. The implants could be positioned precisely as preoperatively planned. The use of zygomatic fixtures after ablative tumor surgery with resection of the maxillary bone provides immediate prosthetic reconstruction without additional bone grafting. Computer-assisted insertion of these implants improves preoperative planning and facilitates clinical procedure.

[Therapy refractory idiopathic thrombocytopenia. Contraindication for dental surgery interventions]. / Therapierefraktäre idiopathische Thrombozytopenie. Kontraindikation für zahnärztlich-chirurgische Eingriffe.

Hemorrhagic diathesis represents a high risk for oral surgery. In clinical practice various kinds of diathetic diseases are seen that are of plasmatic, vascular, thrombocytic and hypertensive origin. Usually these patients will be primarily referred to the hospital as high-risk cases. Therefore, a broad spectrum of diagnostic and therapeutic interdisciplinary methods are available, so that as a rule it is possible to obtain a clear picture of the severity of the bleeding tendency. We represent a case of a 58-year-old woman who had decayed teeth with chronic periodontal and periapical lesions, who could not be treated by oral surgery because of refractory idiopathic thrombocytopenic purpura (ITP) with 1000 platelets/microliters. The patient's history showed that various hematologic concepts had been tried, including splenectomy, but all had failed entirely. After therapy with steroids, immunosuppressive and cytostatic agents, and even after administering immunoglobulins and substitution with platelets, the count did not increase; thus, an absolute contraindication for all kinds of surgery was declared. This rare example indicates that unmanagable bleeding diseases still exist that should be known by dentists and oral surgeons to prevent making deleterious therapeutic decisions.

[Extraoral and intraoral endoscopically assisted management of collum fractures]. / Extraorale und intraorale endoskopisch assistierte Versorgung von Kollumfrakturen.

AIM OF THE STUDY: Using limited extraoral and transoral incisions for an endoscopically assisted open reduction of condylar mandible fractures, the risk of facial nerve damage and extensive visible scars can be reduced. PATIENTS AND METHODS: The endoscopically assisted treatment of 17 consecutive patients with fractures of the condyle was performed from April 1998 to December 1999. Of the 17 patients, 14 had additional mandibular fractures, and 11 of the condylar fractures were dislocated. Of the 17 patients, 9 were treated by submandibular and 8 by transoral approach. Adequate anatomic reduction was achieved by the submandibular and transoral approaches using an endoscopically assisted technique. APPROACHES: In four patients angulated drills and screwdrivers facilitated the transoral treatment of condylar fractures. Transbuccal stab incisions and the use of trocars were not needed in these four patients. The transoral approach proved to be a reliable surgical approach for fractures of the mandibular condyle even when dislocation with lateral override was present. The extraoral approach was used for severely dislocated fractures such as fractures with medial override or comminution.