Raman spectroscopy and U-Net deep neural network in antiresorptive drug-related osteonecrosis of the jaw.

OBJECTIVE: Application of an optical method for the identification of antiresorptive drug-related osteonecrosis of the jaw (ARONJ). METHODS: We introduce shifted-excitation Raman difference spectroscopy followed by U-Net deep neural network refinement to determine bone tissue viability. The obtained results are validated through established histological methods. RESULTS: Discrimination of osteonecrosis from physiological tissues was evaluated at 119 distinct measurement loci in 40 surgical specimens from 28 patients. Mean Raman spectra were refined from 11,900 raw spectra, and characteristic peaks were assigned to their respective molecular origin. Then, following principal component and linear discriminant analyses, osteonecrotic lesions were distinguished from physiological tissue entities, such as viable bone, with a sensitivity, specificity, and overall accuracy of 100%. Moreover, bone mineral content, quality, maturity, and crystallinity were quantified, revealing an increased mineral-to-matrix ratio and decreased carbonate-to-phosphate ratio in ARONJ lesions compared to physiological bone. CONCLUSION: The results demonstrate feasibility with high classification accuracy in this collective. The differentiation was determined by the spectral features of the organic and mineral composition of bone. This merely optical, noninvasive technique is a promising candidate to ameliorate both the diagnosis and treatment of ARONJ in the future.

A Connective Tissue Neoplasm of the Mandibular Angle Mimicking Stafne's Bone Cavity on Panoramic View.

BACKGROUND: When assessing sharply delineated bone lesions of the mandibular angle on X-rays, numerous diagnoses must be considered. The static bone cavity (Stafne's bone cavity, SBC) is a harmless lingual bone depression of the mandibular angle that usually does not require any treatment. It is essential to differentiate this bone deformity from other lesions that may require treatment. CASE REPORT: The 22-year-old patient was referred for further diagnosis and therapy after osteolysis of the mandible was noticed on a panoramic view (PV). The location and size of the lesion was typical of SBC. Only the three-dimensional representation of the lesion on cone beam computed tomographs revealed an intraosseous lesion. Histological examination of the lesion provided evidence of a fibrous neoplasm. CONCLUSION: The typical image of SBC is ambiguous on plain radiographs such as PV. The radiological diagnosis of the lesion should be based on the representation of the region of interest in different planes.

Massive Transoral Bleeding from the Internal Carotid Artery in a Patient With Granulomatosis With Polyangiitis (Wegener).

BACKGROUND: In the oral and maxillofacial area, granulomatosis with polyangiitis (GPA) can lead to extended tissue destruction. CASE REPORT: This is a case report of a life-threatening local complication resulting from a large osseous defect in the cranial base with consecutive massive bleeding from the right internal carotid artery. Intraoperative examination and diagnostic imaging led to neuroradiological interventional treatment by embolization, and in neurosurgical and further reconstructive surgical treatment by the oral and maxillofacial surgeons. The purpose of this case report was to draw attention to the possibly life-threatening local complications of GPA and to discuss the importance of early intervention. CONCLUSION: As a prevention strategy, regular examinations including three-dimensional radiographic diagnostic imaging are important for the early detection of complications and the possible involvement of important structures.

Retrospective analysis of bacterial colonization of necrotic bone and antibiotic resistance in 98 patients with medication-related osteonecrosis of the jaw (MRONJ).

OBJECTIVES: The aim of our study was to describe microbial flora associated with MRONJ and characterize the susceptibility of pathogens to help guide an effective empiric antibiotic treatment in these patients. MATERIALS AND METHODS: A retrospective, single-center analysis was performed, using 116 bone samples from 98 patients. The bone samples were homogenized and subjected to routine culture methods. Growing bacteria were differentiated to the species level using whole-cell mass spectrometry and subjected to susceptibility testing. RESULTS: A highly diverse microbial flora was detected in necrotic bone, with a simultaneous presence of two or more bacterial species in 79% of all patients. In at least 65% of samples, gram-negative isolates were detected. Therefore, bacterial species resistant against ß-lactamase inhibitors were present in at least 70% of all patients. CONCLUSIONS: The empiric choice of antibiotics in MRONJ patients should consider the high rate of gram-negative bacteria and resistance against ß-lactam antibiotics. CLINICAL RELEVANCE: According to recent guidelines and recommendations, systemic antibiotic treatment is a key component in the treatment of all stage 2 and 3 MRONJ patients. We recommend using fluoroquinolones for empiric treatment and emphasize the use of bacterial cultivation and susceptibility testing to enable an effective antibiotic treatment.

Perioperative Management in Patients With Undergoing Direct Oral Anticoagulant Therapy in Oral Surgery - A Multicentric Questionnaire Survey.

AIM: The purpose of this study was to survey the current opinions of hospitals and medical practices concerning the perioperative management of patients undergoing direct oral anticoagulant therapy (DOAC) and discuss recommendations for the clinical practice. MATERIALS AND METHODS: A questionnaire with 13 topics and multiple ordinal-polytomous subitems was designed and sent to 120 Departments of Oral and Maxillofacial Surgery in Austria, Switzerland and Germany, as well as to 85 oral and maxillofacial/oral surgeons in medical offices in Hamburg, Germany. The data were statistically evaluated by Chi-square, Fisher's exact and Jonckheere-Terpstra tests. RESULTS: The rate of response was 42%. Thirty-seven percent of respondents reported treating over 50 patients per year with undergoing DOAC therapy and only 18% assess a high bleeding risk [33% for vitamin K antagonists (VKA)]. In contrast to that, 62% of respondents would interrupt the DOAC therapy for extraction of one tooth, while 94% would continue VKA therapy. Significantly more clinicians apply suture than those in a medical office. The use of additional hemostatic measures varied between clinic and medical practice. There was a clear request for more detailed guidelines. CONCLUSION: The study shows the current opinion for perioperative management of patients undergoing DOAC therapy. Multi-centric studies under controlled conditions are needed for a safer treatment of anticoagulated patients as therapy strategies differ greatly between institutions and therefore a complication analysis is hardly possible.

Evaluation of Periodontal Space Widening in Patients with Antiresorptive Drug-related Osteonecrosis of the Jaws (ARONJ) on Panoramic Radiographs.

BACKGROUND/AIM: The purpose of this study was to evaluate a potential widening of the periodontal space as an initial measurable imaging criterium on panoramic radiographs in patients with the diagnosis of antiresorptive drug related osteonecrosis of the jaw (ARONJ). PATIENTS AND METHODS: A retrospective analysis of panoramic radiographs of 16 patients (12 females and 4 males; mean age is 70.5 years, standard deviation is 14 years) was performed, over a period of 12 months with the diagnosis of ARONJ. Panoramic radiographs of 16 healthy patients (12 females and 4 males; mean age was 70.6 years, standard deviation was 13.8 years) without diagnosis of ARONJ served as controls. All images were taken with the same device and were evaluated by two experienced maxillofacial surgeons and one dentist. RESULTS: Compared to the control group, a mean widening of the periodontal space of 0.06 mm (confidence interval (CI)=0.05-0.17 mm) was found in the study group. However, this difference was not statistically significant. CONCLUSION: Although a very extensive and sophisticated interindividual comparison was performed to evaluate for slight changes of the periodontal space in patients with antiresorptive drug therapy, our results demonstrate that PDS widening is not a predictive parameter for ARONJ. Therefore, our results indicate that panoramic radiographs are not sufficient enough to allow assessment of stages and disease progress in ARONJ patients regarding to periodontal space widening.

Sensitivity and specificity of sentinel lymph node biopsy in patients with oral squamous cell carcinomas using indocyanine green fluorescence imaging.

PURPOSE: The purpose of this clinical study was to evaluate the sensitivity and specificity of cervical sentinel lymph node biopsy after mapping with indocyanine green fluorescence (ICG) for imaging early-stage oral cancer. PATIENTS AND METHODS: A sentinel lymph node biopsy (SLNB) was performed during a selective neck dissection (SND) in 20 patients with oral squamous cell carcinoma (OSCC, cT1 or cT2, N0 status). The sentinel lymph nodes (SLN) were identified using an infrared video camera after ICG injection. Lymph nodes were examined histologically. The endpoint of this study was to investigate the rate of false-negative results in SLNB. RESULTS: Sentinel lymph nodes could be detected after 8.1 min (range 1-22 min). In eight out of 20 cases, lymph node metastases were found during histopathological evaluation of the neck dissection specimen. In four cases a metastasis could be found in the detected SLN (sensitivity 50%). In the other four cases metastases were found in different lymph nodes. Specificity was 100%, positive predictive value 100%, and negative predictive value 75%. CONCLUSION: In this study, reliability of sentinel lymph node biopsy after ICG imaging could not be verified, as there were false-negative results in 50% of the cases. Therefore, SND can still be recommended as for patients with cT1 or cT2 OSCC, and a N0 neck status.

Assessment of tumor margins in head and neck cancer using a 3D-navigation system based on PET/CT image-fusion - A pilot study.

OBJECTIVES: Determination of tumor margins in patients with squamous cell carcinoma of the head and neck (SCCHN) is mostly based on preoperative magnetic resonance imaging (MRI) or computed tomography scans (CT). Local recurrence of disease is often correlated with the presence of positive resection margins after surgical treatment. Positron emission tomography/computed tomography (PET/CT) imaging plays a crucial role in the assessment of patients with SCCHN. The purpose of this study was to determine whether PET/CT could predict tumor extension. METHODS: In 12 patients who underwent surgical treatment of primary SCCHN (Stage III-IV) F18-FDG PET/CT image-fusion was performed on a 3D navigation-system based workstation. Image-guided needle biopsies were obtained from four different, color-coded metabolic areas within the tumor. The histopathological findings were correlated with findings on corresponding PET/CT scans. RESULTS: 81.3% of biopsies from the central area were positive. Specimens taken from the outer metabolic zone were positive in 66.7% of the patients. The highest incidence of positive biopsies was found in the zone adjacent to the outermost area. There was a statistically significant difference in positive tumor histopathology when comparing the various metabolic zones (p = 0.03). CONCLUSION: Exact determination of tumor is an important research topic, although results remain controversial. The results of this study suggest that in some cases PET scans may overestimate tumor extension.

Functional donor site morbidity longer than one year after fibula free flap: A prospective biomechanical analysis.

OBJECTIVES: The fibula free flap is the workhorse procedure for osseous reconstruction. The objective of this study was to investigate long-term functional outcomes of the harvesting site. PATIENTS AND METHODS: About 19 patients (10 male, 9 female, mean age 58.1 years) were available for the long-term analysis 13-51 months after surgery. Jumping mechanography and balance testing on a ground force reaction plate (Leonardo Mechanograph GFRP) were performed before and surgery. The Esslinger Fitness Index (EFI, maximum peak power in W/kg normalized for age and gender) was considered as primary endpoint. Secondary outcomes were maximum force, range of motion in the ankle joint, sensory limitations, the American Orthopedic Foot and Ankle Society Score (AOFAS-Score), and subjective perceptions. RESULTS: We found no significant difference between pre- and postoperative EFI (70.4% versus 66.0%, P = 0.07) and body sway (1.72 cm2 versus 2.60 cm2 , P = 0.093). The AOFAS-Score was reduced by 8.8 points (99.1 points versus 90.3 points, P < 0.001). Dorsal extenstion (31.6° versus 24.1°, P < 0.001) and flexion (32.3 versus 25.6° flexion, P = 0.011) were significantly reduced and 6 patients had chronic pain. CONCLUSIONS: Reduced peak power and balance ability seem to be reversible short-term effects after fibula harvesting. We recommend preoperative patient education and standardized protocols for physiotherapy.

Improved surgical procedure using intraoperative navigation for the implantation of the SPG microstimulator in patients with chronic cluster headache.

INTRODUCTION: The ATI SPG microstimulator is designed to be fixed on the posterior maxilla, with the integrated lead extending into the pterygopalatine fossa to electrically stimulate the sphenopalatine ganglion (SPG) as a treatment for cluster headache. Preoperative surgical planning to ensure the placement of the microstimulator in close proximity (within 5 mm) to the SPG is critical for treatment efficacy. The aim of this study was to improve the surgical procedure by navigating the initial dissection prior to implantation using a passive optical navigation system and to match the post-operative CBCT images with the preoperative treatment plan to verify the accuracy of the intraoperative placement of the microstimulator. METHODS: Custom methods and software were used that result in a 3D rotatable digitally reconstructed fluoroscopic image illustrating the patient-specific placement with the ATI SPG microstimulator. Those software tools were preoperatively integrated with the planning software of the navigation system to be used intraoperatively for navigated placement. Intraoperatively, the SPG microstimulator was implanted by completing the initial dissection with CT navigation, while the final position of the stimulator was verified by 3D CBCT. Those reconstructed images were then immediately matched with the preoperative CT scans with the digitally inserted SPG microstimulator. This method allowed for visual comparison of both CT scans and verified correct positioning of the SPG microstimulator. RESULTS: Twenty-four surgeries were performed using this new method of CT navigated assistance during SPG microstimulator implantation. Those results were compared to results of 21 patients previously implanted without the assistance of CT navigation. Using CT navigation during the initial dissection, an average distance reduction of 1.2 mm between the target point and electrode tip of the SPG microstimulator was achieved. Using the navigation software for navigated implantation and matching the preoperative planned scans with those performed post-operatively, the average distance was 2.17 mm with navigation, compared to 3.37 mm in the 28 surgeries without navigation. CONCLUSION: Results from this new procedure showed a significant reduction (p = 0.009) in the average distance from the SPG microstimulator to the desired target point. Therefore, a distinct improvement could be achieved in positioning of the SPG microstimulator through the use of intraoperative navigation during the initial dissection and by post-operative matching of pre- and post-operatively performed CBCT scans.

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

OBJECTIVES: To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. METHODS: Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. RESULTS: While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. CONCLUSIONS: MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

Optimized 14 + 1 receive coil array and position system for 3D high-resolution MRI of dental and maxillomandibular structures.

OBJECTIVES: The purpose of this study was to design, build and test a multielement receive coil array and position system, which is optimized for three-dimensional (3D) high-resolution dental and maxillomandibular MRI with high patient comfort. METHODS: A 14 + 1 coil array and positioning system, allowing easy handling by the technologists, reproducible positioning of the patients and high patient comfort, was tested with three healthy volunteers using a 3.0-T MRI machine (Siemens Skyra; Siemens Medical Solutions, Erlangen, Germany). High-resolution 3D T1 weighted, water excitation T1 weighted and fat-saturated T2 weighted imaging sequences were scanned, and 3D image data were reformatted in different orientations and curvatures to aid diagnosis. RESULTS: The high number of receiving coils and the comfortable positioning of the coil array close to the patient's face provided a high signal-to-noise ratio and allowed high quality, high resolution, 3D image data to be acquired within reasonable scan times owing to the possibility of parallel image acquisition acceleration. Reformatting the isotropic 3D image data in different views is helpful for diagnosis, e.g. panoramic reconstruction. The visibility of soft tissues such as the mandibular canal, nutritive canals and periodontal ligaments was exquisite. CONCLUSIONS: The optimized MRI receive coil array and positioning system for dental and oral-maxillofacial imaging provides a valuable tool for detecting and diagnosing pathologies in dental and oral-maxillofacial structures while avoiding radiation dose. The high patient comfort, as achieved by our design, is very crucial, since image artefacts due to movement or failing to complete the examination jeopardize the diagnostic value of MRI examinations.

Prospective biomechanical evaluation of donor site morbidity after radial forearm free flap.

Although the radial forearm free flap (RFF) is a commonly-used microvascular flap for orofacial reconstruction, we are aware of few prospective biomechanical studies of the donor site. We have therefore evaluated the donor site morbidity biomechanically of 30 consecutive RFF for orofacial reconstruction preoperatively and three months postoperatively. This included the Mayo wrist score, the Disabilities of the Arm, Shoulder and Hand (DASH) score, grip strength, followed by tip pinch, key pinch, palmar pinch, and range of movement of the wrist. Primary defects were all closed with local full-thickness skin grafts from the donor site forearm, thereby circumventing the need for a second defect. Postoperative functional results showed that there was a reduction in hand strength measured by (grip strength: -24.1%, in tip pinch: -23.3%, in key pinch: -16.5, and in palmar pinch: -19.3%); and wrist movement measured by extension (active=14.3% / passive= -11.5%) and flexion = -14.8% / -8.9%), and radial (-9.8% / -9.8%) and ulnar (-11.0% / -9.3%) abduction. The Mayo wrist score was reduced by 9.4 points (-12.9%) and the DASH score increased by 16.1 points (+35.5%) compared with the same forearm preoperatively. The local skin graft resulted in a robust wound cover with a good functional result. Our results show that the reduction in hand strength and wrist movement after harvest of a RFF is objectively evaluable, and did not reflect the subjectively noticed extent and restrictions in activities of daily living. Use of a local skin graft avoids a second donor site and the disadvantages of a split-thickness skin graft.

Intraindividual comparison of preoperative (99m)Tc-MDP SPECT/CT and intraoperative and histopathological findings in patients with bisphosphonate- or denosumab-related osteonecrosis of the jaw.

PURPOSE: Bisphosphonate- or denosumab-related osteonecrosis of the jaw (BRONJ/DRONJ) requires reliable preoperative assessment of the extent of disease for surgical planning. The aim of this study was to compare the extent of BRONJ/DRONJ as detected by Tc-99m-methylene diphosphonate (MDP) bone scintigraphy with intraoperative and histopathological findings, and to assess the additional value of hybrid single photon emission computed tomography/computed tomography (SPECT/CT) for evaluation of disease. MATERIAL AND METHODS: Twenty-one patients with BRONJ/DRONJ underwent three-phase bone scintigraphy including SPECT/CT. The diagnostic certainty using conventional SPECT or fused SPECT/CT imaging was compared. Location and extent of disease on scintigraphic imaging and pre- and intra-operative clinical assessment were compared. Intraoperative and histopathological findings served as reference standard. RESULTS: A total of 29 sites of BRONJ/DRONJ were histopathologically confirmed in 21 patients. Bone scintigraphy demonstrated increased perfusion in 57.1% of patients, increased blood pool in 76.2%, and increased tracer accumulation at the metabolic phase in all patients. The intensity of tracer accumulation at the metabolic phase correlated significantly with clinical stage of disease (rs = 0.47, p = 0.03). Clinical examination (p < 0.0001), but not SPECT (p = 0.19), underestimated the extent of disease as determined by surgical evaluation. SPECT/CT offered a significantly higher diagnostic certainty (p < 0.0001). CONCLUSION: In patients with BRONJ/DRONJ, the true extent of osseous lesions as determined by surgery is significantly underestimated by clinical examination. Tc-99m-MDP bone scintigraphy can reliably predict the extent of disease. Hybrid SPECT/CT may significantly increase the diagnostic certainty of anatomical localization.

Early detection of pulp necrosis and dental vitality after traumatic dental injuries in children and adolescents by 3-Tesla magnetic resonance imaging.

OBJECTIVES: More than 50% of all children suffer a traumatic dental injury (TDI) during childhood. In many cases, dentists apply root canal treatment (RCT), which is performed on an average of 7-10 days after replantation. Our aim was to evaluate whether RCT is necessary in many cases, and whether revitalization of affected teeth is possible and measurable by visualization using 3T magnetic resonance imaging (MRI). MATERIAL AND METHODS: Seven healthy children with TDI were treated by repositioning of the affected teeth and reduction of alveolar process fractures followed by splinting. Two weeks after initial treatment, splints were removed. After 6 weeks, all children received 3-Tesla (3T), three-dimensional, high-resolution MRI with a 20-channel standard head and neck coil. The mean age of the children (male/female = 5:2) was 10.8 years (range, 8-17 years). In addition, all children received conventional dental examination for tooth vitality and dental sensitivity to cold and tenderness on percussion. RESULTS: 3T MRI provided excellent images that allowed fine discrimination between dental pulp and adjacent tooth. Using four in-house optimized, non-contrast-enhanced sequences, including panoramic reconstruction, the assessment and analysis of the dental pulp was sufficiently feasible. We could demonstrate reperfusion and thus vitality of the affected teeth in 11 sites. In one child, MRI was able to detect nonreperfusion after TDI of the affected tooth. MRI results were confirmed by clinical examination in all cases. As a consequence of this expectant management and proof of reperfusion and tooth vitality by 3T MRI, only one child had to be treated by RCT. CONCLUSION: 3T MRI is a very promising tool for visualization and detection in the field of dental and oromaxillofacial diseases. By using new 3T MRI sequences in children with TDI, we could demonstrate that RCT are not necessary in every case, and thus could prevent unnecessary treatment of children in the future. Larger studies should follow to confirm the potential benefit in clinical practice.

The Nasopalatine Canal in Adults on Cone Beam Computed Tomograms-A Clinical Study and Review of the Literature.

AIM: The aims of this study were to assess the location, morphology and anatomical dimensions of the nasopalatine canal (NPC) on cone beam computed tomographic (CBCT) images and to compare our findings with recent reports on this matter. A detailed knowledge of anatomical variations is mandatory in skeletal surgery of the anterior maxilla. PATIENTS AND METHODS: Two hundred CBCT scans of the mid-facial region were analyzed from adult patients at the Outpatient Clinic of the Department of Oral and Craniomaxillofacial Surgery, University of Hamburg, Germany. Patients were scanned using standard exposure time at normal patient positioning inside the CBCT device. Three-dimensional (3D) CBCT images were carefully analyzed regarding NPC location, morphology and anatomical dimensions, and variations of radiological morphology, with respect to age and gender. RESULTS: In the sagittal plane, the NPC typically appeared as a canal with a mean length±standard deviation (SD) of 11.15±2.87 mm. The oral cavity opening of the canal is the incisive foramen, with a mean diameter of 4.49±1.71 mm. At the entrance to the nasal floor, in most cases, two apertures were found (Y-canal morphology), but also three or four openings were observed. In particular cases, the canal presented a cylindrical aperture with only one exit to the nasal floor. The average width of the NPC at the level of the nasal floor was 3.43±1.54 mm. The labiopalatal width of the NPC measured perpendicular to the long axis of the canal on sagittal plane was 2.48±1.33 mm. Interpretation of NPC morphology was significantly different when analyzing the images in the sagittal plane only, but the technique allowed demonstration of all aspects using the combined 2D/3D interpretation. CONCLUSION: The NPC may exhibit important anatomical variations, both with regard to morphology and its dimensions. To avoid any potential complications during dentoalveolar surgery, careful preoperative evaluation is required. 3D imaging is recommended to determine canal topography and dimensions, and to assess the individual anterior maxilla's dimensions prior to surgical procedures, such as dental implant insertion or bone augmentation.

Intraosseous heat generation during sonic, ultrasonic and conventional osteotomy.

OBJECTIVES: To assess heat generation in osteotomies during application of sonic and ultrasonic saws compared to conventional bur. METHODS: Two glass-fiber isolated nickel-chromium thermocouples, connected to a recording device, were inserted into fresh bovine rib bone blocks and kept in 20 ± 0.5 °C water at determined depths of 1.5 mm (cortical layer) and 7 mm (cancellous layer) and 1.0 mm away from the planned osteotomy site. Handpieces, angulated 24-32°, were mounted in a vertical drill stand, and standardized weights were attached to their tops to exert loads of 5, 8, 15 and 20 N. Irrigation volumes of 20, 50 and 80 ml/min were used for each load. Ten repetitions were conducted using new tips each time for each test condition. The Mann-Whitney-U test was used for statistical analysis (p < 0.05). RESULTS: Both ultrasonic and sonic osteotomies were associated with significantly lower heat generation than conventional osteotomy (p < 0.01). Sonic osteotomy showed non-significantly lower heat generation than ultrasonic osteotomy. Generated heat never exceeded the critical limit of 47 °C in any system. Variation of load had no effect on heat generation in both bone layers for all tested systems. An increased irrigation volume resulted in lower temperatures in both cortical and cancellous bone layers during all tested osteotomies. CONCLUSION: Although none of the systems under the conditions of the present study resulted in critical heat generation, the application of ultrasonic and sonic osteotomy systems was associated with lower heat generation compared to the conventional saw osteotomy. Copious irrigation seems to play a critical role in preventing heat generation in the osteotomy site.

Value of intra- and post-operative cone beam computed tomography (CBCT) for positioning control of a sphenopalatine ganglion neurostimulator in patients with chronic cluster headache.

INTRODUCTION: The objective of this study was to determine whether postoperative control of the neurostimulator placement within the pterygopalatine fossa (PPF) by means of 3-dimensional (3D) cone beam computed tomography (CBCT) was of therapeutic relevance compared to intraoperative CBCT imaging alone. MATERIAL AND METHODS: Immediately after implantation of the sphenopalatine ganglion (SPG) neurostimulator, intraoperative CBCT datasets were generated in order to visualize the position of the probe within the PPF. Postoperatively, all patients received a CBCT for comparison with intraoperatively acquired radiographs. RESULTS: Twenty-four patients with cluster headache (CH) received an SPG neurostimulator. In 4 patients, postoperative CBCT images detected misplacement not found in intraoperative CBCT. In 3 cases, electrode tips were misplaced into the maxillary sinus and in 1 case into the apex of the PPF superior to the suspected location of the SPG. Immediate revision with successful repositioning within 3 days was done in 2 patients and a deferred reimplantation in 1 patient within 6 months. One patient declined revision. CONCLUSION: We were able to demonstrate the clinical value of postoperative dental CBCT imaging with a wide region of interest (ROI) due to a superior image quality compared with that achieved with intraoperative medical CBCT. Although intraoperative 3D CBCT imaging of electrode placement is helpful in the acute surgical setting, resolution is, at present, too low to safely exclude misplacement, especially in the maxillary sinus. High-resolution postoperative dental CBCT allows rapid detection and revision of electrode misplacement, thereby avoiding readmission and recurrent tissue trauma.

Evaluation of four different optimized magnetic-resonance-imaging sequences for visualization of dental and maxillo-mandibular structures at 3 T.

OBJECTIVES: The purpose of this study was to evaluate four in-house optimized, non-contrast enhanced sequences for MRI-investigation of maxillo-mandibular and dental structures by use of 3 T. METHODS: 12 volunteers with different dental status were examined by using a 3 T MRI with a 20-channel standard head-and-neck coil. All images performed were evaluated by using 3D-techniques, with different slice-thicknesses, in 3D T1- and T2-weighted sequences, as well as by using new techniques of image depictions. In addition phantom measurements were performed to estimate the extent of image artefacts caused by retainers and metal implants. RESULTS: Mean age of the participants was 33 years (range, 25.5-62.75 years), and the sex ratio was 5 females to 7 males. We identified different techniques to improve osseous and dental structures, despite problems caused by dental implants, tooth crowns or braces. CONCLUSION: The sequences evaluated offered excellent visualization in 2D and 3D of osseous and dental structures. Anatomical, osseous and dental structures were described at their ROI, in relation to patients with dental and head and neck pathologies. The ability to detect and distinguish pathological processes as soon as possible in 3D with excellent image quality avoiding ionizing radiation remains a challenging domain.

Stimulation of the sphenopalatine ganglion in intractable cluster headache: expert consensus on patient selection and standards of care.

CONTEXT AND OVERVIEW: Chronic cluster headache (CCH) is a debilitating headache disorder with a significant impairment of the patients' lives. Within the past decade, various invasive neuromodulatory approaches have been proposed for the treatment of CCH refractory to standard preventive drug, but only very few randomized controlled studies exist in the field of neuromodulation for the treatment of drug-refractory headaches. Based on the prominent role of the cranial parasympathetic system in acute cluster headache attacks, high-frequency sphenopalatine ganglion (SPG) stimulation has been shown to abort ongoing attacks in some patients in a first small study. As preventive effects of SPG-stimulation have been suggested and the rate of long-term side effects was moderate, SPG stimulation appears to be a promising new treatment strategy. AIMS AND CONCLUSION: As SPG stimulation is effective in some patients and the first commercially available CE-marked SPG neurostimulator system has been introduced for cluster headache, patient selection and care should be standardized to ensure maximal efficacy and safety. As only limited data have been published on SPG stimulation, standards of care based on expert consensus are proposed to ensure homogeneous patient selection and treatment across international headache centres. Given that SPG stimulation is still a novel approach, all expert-based consensus on patient selection and standards of care should be re-reviewed when more long-term data are available.