Development of a new critical size defect model in the paranasal sinus and first approach for defect reconstruction-An in vivo maxillary bone defect study in sheep.

Fractures of the paranasal sinuses often require surgical intervention. Persisting bone defects lead to permanent visible deformities of the facial contours. Bone substitutes for reconstruction of defects with simultaneous induction of new bone formation are not commercially available for the paranasal sinus. New materials are urgently needed and have to be tested in their future area of application. For this purpose critical size defect models for the paranasal sinus have to be developed. A ≥2.4 cm large bilateral circular defect was created in the anterior wall of the maxillary sinus in six sheep via an extraoral approach. The defect was filled with two types of an osteoconductive titanium scaffold (empty scaffold vs. scaffold filled with a calcium phosphate bone cement paste) or covered with a titanium mesh either. Sheep were euthanized after four months. All animals performed well, no postoperative complications occured. Meshes and scaffolds were safely covered with soft tissue at the end of the study. The initial defect size of ≥2.4 cm only shrunk minimally during the investigation period confirming a critical size defect. No ingrowth of bone into any of the scaffolds was observed. The anterior wall of the maxillary sinus is a region with low complication rate for performing critical size defect experiments in sheep. We recommend this region for experiments with future scaffold materials whose intended use is not only limited to the paranasal sinus, as the defect is challenging even for bone graft substitutes with proven osteoconductivity. Graphical abstract.

A fully ingrowing implant for cranial reconstruction: Results in critical size defects in sheep using 3D-printed titanium scaffold.

Current alloplastic materials such as PMMA, titanium or PEEK don't show relevant bone ingrowth into the implant when used for cranioplasty, ceramic implants have the drawback being brittle. New materials and implant designs are urgently needed being biocompatible, stable enough for cranioplasty and stimulating bone formation. In an in vivo critical size sheep model circular cranial defects (>2.4 cm) were covered with three different types of a 3D-printed porous titanium scaffolds with multidirectional, stochastically distributed architecture (uncoated scaffold, hydroxyapatite-coated scaffold, uncoated scaffold filled with a calcium phosphate bone cement paste containing ß-TCP granules). An empty titanium mesh served as control. Among the different investigated setups the hydroxyapatite-coated scaffolds showed a surprisingly favourable performance. Push-out tests revealed a 2.9 fold higher force needed in the hydroxyapatite-coated scaffolds compared to the mesh group. Mean CT density at five different points inside the scaffold was 2385HU in the hydroxyapatite-coated group compared to 1978HU in the uncoated scaffold at nine months. Average lateral bone ingrowth after four months in the hydroxyapatite-coated scaffold group was up to the implant center, 12.1 mm on average, compared to 2.8 mm in the control group covered with mesh only. These properties make the investigated scaffold with multidirectional, stochastically distributed structure superior to all products currently on the market. The study gives a good idea of what future materials for cranioplasty might look like.

Interdisciplinary management of skull base surgery.

Skull base surgery remains one of the challenging areas in the field of cranio-maxillofacial surgery, otolaryngology and neurosurgery. Subsequent reconstruction of bone and soft tissue are an essential component to restore function and appearance after ablative surgery. Establishment of interdisciplinary tumor boards with presentation of the individual patient cases have become standard. Multiplanar reconstruction using MRI or CT imaging techniques combined with virtual 3D planning allow precise planning of the procedures. Intraoperative navigation helps for complete resection of malignant findings with safety margins; surgical approaches provide a good overview of the surgical site. Reconstruction using local flaps have a low complication rate with equally reliable results in reconstruction of small tissue defects. Free flap surgery makes reconstruction of large tissue defects possible. Alloplastic materials are alternatively used for reconstruction of bone defects. Based on selected patients, treatment algorithms and standard surgical procedures in extracerebral skull base surgery will be illustrated. Current techniques and new approaches will be discussed with emphasize on hard and soft tissue reconstruction.

Medication-related osteonecrosis of the mandible: an unusual presentation and treatment.

A 71-year-old woman was referred to the clinic with extensive medication-related osteonecrosis of the jaw (MRONJ) involving the mandible. She had received 7 years of zoledronate therapy. On cone beam computed tomography, the MRONJ presented as a large sequestrum spanning from the left to the right condylar process, surrounded by thick sub-periosteal bone. The sequestrum was excised via an intraoral approach, leaving the newly formed sub-periosteal bone as a neo-mandible. The patient recovered well from the operation and was discharged 5 days after surgery. She healed completely without complications. This case report presents an alternative surgical treatment that may be considered if there is clinically stable sub-periosteal bone surrounding extensive MRONJ.

Retrospective evaluation of diagnostic accuracy of free flap monitoring with the Cook-Swartz-Doppler probe in head and neck reconstruction.

The Cook-Swartz-Doppler probe is an easy to handle and reliable tool for free flap monitoring. In the head and neck region different confounders can affect the read out. We therefore analyzed the use of the Doppler probe regarding these potential difficulties and to compare the diagnostic accuracy in arterial or venous monitoring of free flaps in the head and neck region. A retrospective study was performed in which all patients were included who underwent free flap surgery in the head and neck region in the Department of Plastic Surgery and the Department of Maxillofacial Surgery of our institution between 2010 and 2018 and were monitored with an implanted Doppler probe. 147 free tissue transfers were included. No significance was found for arterial and venous placement of the Doppler probe for sensitivity (artery 83.3%; vein 84.6%; p = 0.87), specificity (artery 89.2%; vein 96.1%; p = 0.17) and negative predictive value (artery 96.7%; vein 94.2%; p = 0.55). A better positive predictive value for placing the Doppler probe around the artery (82.7%) than the vein (61.1%) was found in our study (p = 0.056). The better positive predictive value in arterial monitoring suggests that this is the more reliable measuring method to assess flap perfusion in the head and neck region.

Lymph node abscess caused by Francisella tularensis - a rare differential diagnosis for cervical lymph node swelling: a case report.

BACKGROUND: Cervical lymph node swelling is quite a common symptom mainly caused by infections in the face or as metastasis of a malignant tumor. In infection cases in particular, rare diseases should never be overlooked. With an incidence of 120 cases in the United States of America (USA) and approximately 25 cases in Germany per year, infection with the pathogen Francisella tularensis is one of these rare diseases that can cause massive lymph node swellings and might even be fatal. CASE PRESENTATION: The example of a healthy 67-year-old German woman who was treated at our university hospital presents a typical progression of a localized form of tularemia. The pathogen could be identified in a universal 16S ribosomal deoxyribonucleic acid (DNA) polymerase chain reaction. Pathogen-specific treatment with lymph node abscess incision, daily rinsing of the abscess cavity, and orally administered antibiotic therapy with doxycycline could cure our patient completely without any remaining complications. CONCLUSION: In patients with cervical lymph node swelling caused by infection it is indispensable to perform specific identification of the pathogen for further local and specific antibiotic treatment. Possible infections with atypical bacteria like Francisella tularensis should never be ignored. Universal polymerase chain reactions are a suitable method for early detection of such rare pathogens.

The influence of dexamethasone on postoperative swelling and neurosensory disturbances after orthognathic surgery: a randomized controlled clinical trial.

BACKGROUND: Orthognathic surgery is associated with considerable swelling and neurosensory disturbances. Serious swelling can lead to great physical and psychological strain. A randomized, prospective, controlled clinical trial was realized in order to evaluate the effect of a preoperative intravenous dexamethasone injection of 40 mg on postoperative swelling and neurosensory disturbances after orthognathic surgery. METHODS: Thirty-eight patients (27 male and 11 female) patients, all with the indication for an orthognathic surgery, were enrolled in this study (mean age: 27.63 years, range: 16-61 years) and randomly divided into two groups (study group/ control group). Both groups underwent either maxillary and/or mandibular osteotomies, resulting in three subgroups according to surgical technique (A: LeFort I osteotomy, B: bilateral sagittal split osteotomy (BSSO), C: bimaxillary osteotomy). The study group received a single preoperative intravenous injection of 40 mg dexamethasone. Facial edema was measured by 3D surface scans on the 1st, 2nd, 5th, 14th and 90th postoperative day. Furthermore, neurosensory disturbances on the 2nd, 5th, 14th and 90th postoperative day were investigated by thermal stimulation. RESULTS: Facial edema after LeFort I osteotomy, BSSO and bimaxillary osteotomy showed a significant decrease in the study group compared to the control group (P = 0.048, P = 0.045, P < 0.001). The influence of dexamethasone on neurosensory disturbances was not significant for the inferior alveolar nerve (P = 0.746) or the infraorbital nerve (P = 0.465). CONCLUSIONS: Patients undergoing orthognathic surgery should receive a preoperative injection of dexamethasone in order to control and reduce edema. However, there was no influence of dexamethasone on reduction of neurosensory disturbances. TRIAL REGISTRATION: DRKS00009033 .

Comparison of virtual and titanium clip marking of tumour resection margins for improved radiation planning in head and neck cancer surgery.

Communication between the surgeon and the radiation oncologist is improved with the use of virtual models of the final tumour resection, combining three-dimensional imaging and conventional clip marking with computer-aided navigation. This investigation was designed to determine the deviation of virtual marking procedures compared to conventional marking by titanium ligature clips in oral cancer with different localizations. Seventeen patients with surgically placed clips and virtual landmarks on the resection margin after complete tumour ablation were evaluated. To determine whether the virtual landmarks remain predictive of the resection margin, the deviation of the virtual points from their corresponding clips was analyzed by measuring the distance between their centres of gravity. In total, 189 clips were evaluated. Metric analyses of the deviation between the virtual points and clips showed a deviation of 2.3 ± 0.6mm for tumours with a maxilla localization, 7.2 ± 2.5mm for tumours with a mandible localization, and 12.6 ± 3.8mm for tumours with a tongue localization. A significant statistical relationship was demonstrated in the virtual point-clip deviation as a function of tumour localization. Virtual marking of maxillary tumour resection margins allows accurate definition of the former tumour bed and could lead to novel adjuvant treatment strategies.

Recurrence rate and shift in histopathological differentiation of oral squamous cell carcinoma ­ A long-term retrospective study over a period of 13.5 years.

OBJECTIVE: Little information is available as to whether recurrences of oral squamous cell carcinoma (OSCC) show different histopathological grades than the primary tumor and whether postoperative radiotherapy (PORT) influences the grade of differentiation in the case of recurrence. The objective of this study was the evaluation of recurrence rates and change in differentiation. MATERIAL AND METHODS: This retrospective, single-institution cohort study included surgically treated OSCC patients over a 13-year period (2000-2013). The relationship among tumor size, lymph node metastases, and recurrence rate of OSCC was investigated. Primary tumor differentiation was compared with differentiation of recurrence. RESULTS: A total of 429 patients (277 men and 152 women) were included in this study. Of these, 124 (28.9%) received PORT. The incidence of primary cervical metastases increased significantly with tumor size (p < 0.001). Recurrence developed in 82 patients (19.1%). Stage T1/T2 showed a significantly lower recurrence rate than stage T3/T4 (16.3% vs. 30.2%) (p < 0.01). A total of 23 (30.7%) patients with recurrence showed a change in differentiation. CONCLUSION: Increasing primary tumor size correlates with incidence of cervical metastases and recurrence rate. Initial cervical metastases show no effect on recurrence rates. Differentiation of primary tumor does not correlate with the recurrence rate. The majority of recurrences show consistent histopathological grading.

Sensitivity and specificity of cone beam computed tomography in thin bony structures in maxillofacial surgery ­ A clinical trial.

INTRODUCTION: Cone-Beam Computed Tomography (CBCT) has become widely used in dentistry and maxillofacial surgery. Accuracy, sensitivity and specificity of thin bony structures below 0.5 mm have been subject of some in vitro studies. This prospective in vivo study investigates the correlation between preoperative CBCT-imaging and intraoperative clinical examination of thin bony structures. We hereby present results from daily clinical routine. METHODS: A total number of 80 sites in 64 patients has been examined to differentiate between preoperative 3D imaging and clinical measurements on cystic lesions in maxilla and mandible. Different CBCT-devices with a voxel size ranging from 0.08 mm to 0.4 mm were used. RESULTS: Overall-specificity found for detecting thin bony structures of the human jaw is 13.89%, overall sensitivity is 100%, positive predictive value (PPV) is 58.67% and negative predictive value (NPV) is 100%. DISCUSSION: Image quality is the key to make use of additional information CBCT provides and depends on spatial, temporal and contrast resolution. CBCT does not depict reliably thin bony structures of the jaw, even if high voxel resolution is used. CONCLUSION: In selected cases using high resolution protocols should be considered despite affecting the patient with higher doses of radiation.

A prospective study of factors influencing morbidity after iliac crest harvesting for oral onlay grafting.

OBJECTIVE: The present study evaluates the morbidity after iliac crest harvesting from the anterior iliac rim for oral onlay grafting and identifies influential factors. MATERIAL AND METHODS: Twenty partially edentulous or edentulous patients (15 females and 5 males) with a mean age of 54.25 years (range 20-78 years, SD 13.86 years, remaining bone height <5 mm of the alveolar ridge) underwent iliac onlay bone grafting. The postoperative clinical morbidity was classified in minor and major complications and was evaluated with respect to body mass index (BMI). RESULTS: The grafting procedure was successfully performed in all patients with a mean BMI of 23.34 (range 18-29, SD 3.36). A significant difference between BMI and walking aid necessity (p = 0.018) was demonstrated, but no difference between BMI and hip pain, duration of disturbance, gait disturbance, complication rate, and sensory loss was identified (p > 0.05). Between hip pain and scar length, age and hip/jaw pain did not demonstrate a significant difference (p > 0.05). Postoperative complications were minor and consisted of hematoma, seroma, and transient sensory disturbance. CONCLUSION: Patients undergoing bone harvest from the anterior superior iliac crest with oral grafting show a low minor complication rate and a high overall satisfaction of 95%.

Design and development of a virtual anatomic atlas of the human skull for automatic segmentation in computer-assisted surgery, preoperative planning, and navigation.

PURPOSE: Manual segmentation of CT datasets for preoperative planning and intraoperative navigation is a time-consuming procedure. The purpose of this study was to develop an automated segmentation procedure for the facial skeleton based on a virtual anatomic atlas of the skull, to test its practicability, and to evaluate the accuracy of the segmented objects. MATERIALS AND METHODS: The atlas skull was created by manually segmenting an unaffected skull CT dataset. For automated segmentation of cases via IPlan cranial (BrainLAB, Germany), the atlas skull underwent projection, controlled deformation, and a facultative threshold segmentation within the individual datasets, of which 16 routine CT (13 pathologies, 3 without) were processed. The variations of the no-threshold versus threshold segmentation results compared to the original were determined. The clinical usability of the results was assessed in a multicentre evaluation. RESULTS: Compared to the original dataset, the mean accuracy was [Formula: see text] mm for the threshold segmentation and 0.6-1.4 mm for the no-threshold segmentation. Comparing both methods together, the deviation was [Formula: see text] mm. An isolated no-threshold segmentation of the orbital cavity alone resulted in a mean accuracy of [Formula: see text] mm. With regard to clinical usability, the no-threshold method was clearly preferred, reaching modal scores of "good" to "moderate" in most areas. Limitations were seen in segmenting the TMJ, mandibular fractures, and thin bone in general. CONCLUSION: The feasibility of automated skull segmentation was demonstrated. The virtual anatomic atlas can improve the preprocessing of skull CT scans for computer assisted craniomaxillofacial surgery planning.

[Function-retaining reconstruction after orbital trauma]. / Funktionserhaltende Rekonstruktion nach Orbitatrauma.

Precise anatomical reconstruction of extensive orbital fractures is a challenging procedure for surgeons. Computer-assisted technologies, anatomical preformed implants and the possibility of acquiring 3D images using cone beam computed tomography are considered as the new standards. In this short review these applications are presented.

Morphometric analysis - Cone beam computed tomography to predict bone quality and quantity.

AIM: Modified quantitative computed tomography is a method used to predict bone quality and quantify the bone mass of the jaw. The aim of this study was to determine whether bone quantity or quality was detected by cone beam computed tomography (CBCT) combined with image analysis. MATERIALS AND PROCEDURES: Different measurements recorded on two phantoms (Siemens phantom, Comac phantom) were evaluated on images taken with the Somatom VolumeZoom (Siemens Medical Solutions, Erlangen, Germany) and the NewTom 9000 (NIM s.r.l., Verona, Italy) in order to calculate a calibration curve. The spatial relationships of six sample cylinders and the repositioning from four pig skull halves relative to adjacent defined anatomical structures were assessed by means of three-dimensional visualization software. RESULTS: The calibration curves for computer tomography (CT) and cone beam computer tomography (CBCT) using the Siemens phantom showed linear correlation in both modalities between the Hounsfield Units (HU) and bone morphology. A correction factor for CBCT was calculated. Exact information about the micromorphology of the bone cylinders was only available using of micro computer tomography. CONCLUSION: Cone-beam computer tomography is a suitable choice for analysing bone mass, but, it does not give any information about bone quality.

Navigation-guided resection with immediate functional reconstruction for high-grade malignant parotid tumour at skull base.

The authors report a case of navigation-guided tumour ablation of a high-grade epithelial-myoepithelial carcinoma of the right parotid gland extending to the skull base. Immediate functional reconstruction of the mandible with a prosthetic temporomandibular joint and facial nerve was performed. Postoperative follow-up showed no evidence of local tumour recurrence or distant metastasis with satisfactory temporomandibular and facial nerve function.

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.

Life-threatening complications associated with acute monocytic leukaemia after dental treatment.

It is highly recommended to conduct a prophylactic check for any dental problems on patients who suffer from leukaemia before chemotherapy begins. Bacteraemia caused by oral microflora may be very dangerous for patients with haematological malignancies. However, it should be noted that the prophylactic process itself might bring about life-threatening complications if there is only a short interval between dental treatment and the beginning of chemotherapy, or if the dental treatment is too aggressive. We present a case where this prophylactic procedure produced life-threatening complications for a patient with acute myeloid leukaemia.

Preliminary functional results of endoscope-assisted transoral treatment of displaced bilateral condylar mandible fractures.

Temporomandibular joint (TMJ) function was evaluated following endoscope-assisted transoral open reduction and miniplate fixation of displaced bilateral condylar mandibular fractures. The transoral treatment of bilateral condylar fractures was performed in 13 patients from May 2000 to December 2004. Eleven of the 13 patients had additional mandibular fractures. Out of 26 fractures of the condylar process, 11 were located at the condylar neck and 15 were subcondylar. One, 6 and 12 months after surgery TMJ function was evaluated. Anatomic reduction was achieved using an endoscope-assisted transoral approach even when the condylar fragment was displaced medially and in fractures with comminution. Good TMJ function was noted 6 and 12 months after surgery. Mouth opening was measured to be more than 40 mm without deviation. Postoperative range of motion with a satisfying lateral excursion was found. Early rehabilitation and pre-injury TMJ function was achieved following minimally invasive anatomic fracture reduction.

Topographical CT-data analysis of the human orbital floor.

The aim of this study was to evaluate the topographical anatomy of the human orbital floor for the production of prefabricated implants on the basis of computer tomography data. A database of 279 CT scans of Caucasian patients without traumatic deformation of the midface was analysed. 3D-image segmentation of the midfacial skeleton was performed using a computer-assisted protocol. A virtual plane (50 x 50 mm (2)) was constructed using defined landmarks above the orbital floor. An automated procedure was used to measure the distance between the orbital floor and the constructed plane at 400 distinct points. A mathematical algorithm was used to analyse the data, and to calculate a map of the orbital floor. Statistical analysis of the data revealed that orbital floor topography could be classified as distinct clusters. There were 12 variations of orbital floor anatomy: three unique patterns of the orbital floor for the right orbit and three corresponding patterns for the left side, all of which varied between the sexes. The 12 patterns were constructed with a statistical confidence interval of 1.36+/-0.6mm.

Individually preformed titanium mesh implants for a true-to-original repair of orbital fractures.

The purpose of this investigation is to present the results using preoperatively-formed titanium mesh implants for a true-to-original primary repair of extensive orbital floor and medial wall fractures. Individually preformed implants were used to repair extensive orbital floor injuries in 19 patients at the University Hospital, Freiburg. The form of the orbital floor and walls was analysed by preoperative diagnostic CT scan data. The form of the virtual reconstructed orbit was transformed into a model of the orbital cavity by a template machine. Postoperative imaging by or CT scan verified the exact 3D reconstruction of the orbital cavity 'true to original'. None of the patients demonstrated diplopia or enophthalmos postoperatively. Using individually preformed titanium mesh implants, the accuracy of the 3D orbital reconstruction was within a range of 1mm. The reconstruction using preformed implants proved to be less time consuming, more precise and less invasive, compared to 'free hand' efforts, for the repair of orbital injuries using titanium mesh and calvarial grafts.