CBCT device dependency on the transfer accuracy from computer-aided implantology procedures.

OBJECTIVES: To evaluate the potential influence of different cone-beam computed tomography (CBCT) devices on the transfer accuracy of an open-source system for computer-aided implantology (CAI). MATERIAL AND METHODS: A total of 108 implants in 18 partially edentulous patient-equivalent models were planned and fully guided implants were inserted using an open-source CAI system with three different CBCT devices. After follow-up CBCT and fiducial marker-matching procedure, linear horizontal, vertical, and maximal three-dimensional deviations, as well as angle deviations between the virtual planning data and the surgical results were calculated. Variance analysis was carried out to prove whether or not the observed differences between the CBCT devices were statistically significant. RESULTS: The observed mean three-dimensional deviation rates between virtually planned and achieved implant positions varied by around 400 µm (45%) at the implant's base and around 540 µm (50%) at the implant's tip in dependence to the applied CBCT device. Mean vertical deviations varied around 370 µm (76%) at the implant's base and 350 µm (69%) at the implant's tip, whereas axes deviations varied around 0.81° (40%) between the three investigated CBCT devices. Except for the axes deviations and the horizontal linear deviations at the implants base, observed differences reached significance level between the CBCT devices. CONCLUSIONS: Until now, the potential influence from different CBCT devices on the transfer accuracy of CAI systems has not yet been investigated. Data from the present study confirm for the first time the in vitro CBCT device dependency on the transfer accuracy of CAI systems reaching up to axes deviations of 0.6 angle degree and linear deviations around half a millimeter.

Tocilizumab: Another medication related to osteonecrosis of the jaws? A case report and literature review.

Introduction: Medication-related osteonecrosis of the jaw (MRONJ) is a serious complication in patients receiving antiresorptive medication, such as bisphosphonates and denosumab, for different oncologic and non-oncologic diseases. Here, we report a case of MRONJ in a patient treated with tocilizumab, a humanized anti-interleukin-6 receptor antibody that effectively treats moderate to severe rheumatoid arthritis in adults. Case description: A 45-year-old female patient diagnosed with severe rheumatoid arthritis, who had been undergoing intravenous tocilizumab therapy for three years without history of bisphosphonate use, was referred to our department. Four weeks previously, several teeth in the maxilla and mandible were removed under local anesthesia by her dentist. Two weeks after the extractions, she felt pain in both jaws. We diagnosed wound dehiscence and delayed healing of the alveolar bone after the tooth extractions. Digital volume tomography showed persistent dry alveolar sockets. The patient underwent surgical debridement of necrotic bone, and intravenous antibiotics were administered in hospital. Five months later, wound dehiscence reoccurred in the same regions. Histopathological analysis of bone biopsies revealed a diagnosis of MRONJ. Four months later, wound dehiscence occurred in the left maxillary alveolar ridge, and local bone resection was performed under antibiotic treatment. Twenty-four months after the last surgery, wound dehiscence had healed completely without signs of recurrence. Discussion: Osteomyelitis of the jaw in patients treated with tocilizumab has not been reported often. This case confirms the potential role of this interleukin-6 receptor inhibitor in the pathogenesis of MRONJ and shows that patients who receive tocilizumab with MRONJ-like symptoms should be closely monitored. The pathomechanism of MRONJ under tocilizumab therapy remains unclear, so dental practitioners, maxillofacial surgeons, and rheumatologists should look for signs of MRONJ in patients receiving tocilizumab to prevent MRONJ onset.

Eggerthia catenaformis infection originating from a dental abscess causes severe intestinal complications and osteomyelitis of the jaw.

Introduction: Odontogenic foci may result to generalized infections spreading the bacteria through contiguous anatomic cavities or hematogenous spread. The most reported secondary infections caused by oral pathogens are intracranial abscesses. Although, few reports in the literature describe the bacterial spread to extracranial locations. Case description: We describe the case of a 52-year-old male Caucasian patient who was admitted to our hospital suffering from severe sepsis caused by a submandibular abscess. Eggerthia catenaformis was detected in blood and abscess material (confirmed by MALDI-TOF mass spectrometry). The patient subsequently developed a perihepatic abscess and colon perforation, and was stabilized after several surgical interventions. He remained hospitalized for 66 days receiving intravenous antibiotics. Five months later, jaw osteonecrosis with Actinomyces contamination was detected in the left mandible, which also had to be treated surgically. Three years after the last surgery, no signs of recurrence have been detected. Discussion: Oral and maxillofacial surgeons should understand the characteristics of systemic infections, in which the potentially causal intraoral odontogenic foci often lack acute symptoms. If other origins of infection are not detected, elimination of the potentially causal odontogenic foci should be performed. However, the decision making criteria to eliminate suspected causal teeth is needed to be elucidated through more studies.

Evaluation of maxillary sinus anatomy by cone-beam CT prior to sinus floor elevation.

PURPOSE: Surgical complications during sinus floor elevation are frequently caused by septa in the maxillary sinus. In this study, the prevalence of septa was retrospectively determined via three-dimensional imaging to assess the necessity for appropriate imaging prior to sinus floor elevation. MATERIALS AND METHODS: The cone-beam computed tomography scans of 1,029 consecutive patients were evaluated to assess the prevalence of septa, taking into account patient age and sex as well as the number and orientation of septa and their locations. If septa were present, the height was measured and the orientation was determined. RESULTS: Septa were found in 47% of patients and 33.2% of sinuses. There was no statistical difference in prevalence with respect to age, sex, or side. Most patients with septa showed one septum in one sinus (24.6%); 13.7% showed one septum in each sinus. Other combinations (up to three septa per sinus) were found in 8.7% of patients. Septa were most commonly located in the first molar region (256 septa), followed by the second molar region (225 septa), the third molar region (144), second premolar region (136), the first premolar region (44), and the canine region (5). The mean septal height was 11.7 +/- 6.08 mm for septa in a sagittal orientation (n = 206, 25.3%; maximum height of 37 mm) and 7.3 +/- 5.08 mm for those oriented transversely (n = 608, 74.7%; maximum height of 36 mm). The variance was larger for the sagittal orientation group (37.03 mm) than for transversely oriented septa (25.9 mm). CONCLUSION: Septa were found in 47% of the patients in this sample. Appropriate imaging prior to performing sinus surgery seems justified, since complications and the success rate of sinus floor elevation are clearly related to the presence of septa. Int J Oral Maxillofac Implants 2010;25:258-265.

Accuracy of a newly developed integrated system for dental implant planning.

OBJECTIVES: To evaluate the accuracy of the first integrated system for cone-beam CT (CBCT) imaging, dental implant planning and surgical template-aided implant placement. MATERIALS AND METHODS: On the basis of CBCT scans, a total of 54 implant positions were planned for 10 partially edentulous anatomical patient-equivalent models. Surgical guides were ordered from the manufacturer (SICAT). Two different types of guidance were assessed: for assessment of the SICAT system inherent accuracy vendor's titanium sleeves of 2 mm internal diameter and 5 mm length were utilized for pilot drills. The guide sleeves of the NobelGuide system were implemented for fully guided surgery and implant insertion. Deviations perpendicular to the implant axes at the crestal and apical end, as well as the angle deviations between the virtual planning data and the surgical results, were measured utilizing a follow-up CBCT investigation and referential marker-based registration. RESULTS: The SICAT system inherent mean deviation rates for the drilled pilot osteotomies were determined to be smaller than 500 mum even at the apical end. Mean angle deviations of 1.18 degrees were determined. Utilizing the NobelGuide sleeve-in-sleeve system for fully guided implant insertion in combination with the investigated template technology enabled to insert dental implants with the same accuracy. Crestal deviations, in general, were significantly lower than the apical deviations. CONCLUSION: Although hardly comparable due to different study designs and measurement strategies, the investigated SICAT system's inherent accuracy corresponds to the most favourable results for computer-aided surgery systems published so far. In combination with the NobelGuide surgical set for fully guided insertion, the same accuracy level could be maintained for implant positioning.

Comparison of cone-beam imaging with orthopantomography and computerized tomography for assessment in presurgical implant dentistry.

PURPOSE: To establish a basis for weighing the potential diagnostic and therapeutic benefits of three-dimensional cone-beam (CB) data sets in contrast to digital orthopantomography (OPG) and computerized tomography (CT) in implant dentistry. MATERIALS AND METHODS: Twenty-seven patients requiring implant surgery received a single presurgical CB scan. A follow-up digital OPG was taken within a maximal postsurgical period of 2 weeks. For comparison purposes, a control group of 29 patients receiving CT as well as CB diagnosis was analyzed. Image quality of the different modalities was ranked retrospectively by five experienced examiners (from excellent to insufficient) for up to 10 defined criteria, including general image quality and several specific structures. The results were analyzed statistically, and interobserver agreement was calculated using intraclass correlation coefficients (ICCs). RESULTS: The median rating for all investigated criteria was good for CB imaging and between good and insufficient for OPG in the dental implant group. Except for general image quality, statistical analysis showed that CB imaging was significantly superior to OPG imaging for all investigated anatomic structures. With a few exceptions, all investigated anatomic structures in CT and CB imaging were rated excellent in the control group. No significant difference between CT and CB imaging was detected in the control group for all investigated criteria. With a few exceptions, ICCs were higher for CB images than for OPG. In the control group, ICCs for CT and CB images were similar, with a few exceptions. CONCLUSION: The results of the present study confirm superior radiographic visualization for all important high-contrast structures in presurgical implant dentistry assessment for CB imaging in contrast to OPG and a CT-like degree of information for high-contrast structures in CB data sets. Clinically, however, the elevated radiation dosages transmitted by CB imaging must be taken into account.

Vertical ridge augmentation using xenogenous bone blocks: a histomorphometric study in dogs.

PURPOSE: Because vertical ridge augmentation with autogenous bone blocks carries with it a risk of graft resorption and donor site morbidity, the aim of the present study was to compare histologically the healing following vertical ridge augmentation using screwable, xenogenous deproteinized blocks or autologous bone blocks in dogs. MATERIALS AND METHODS: Standardized vertical mandibular defects were surgically created in edentulous ridges of six foxhounds. Two bone blocks (6 x 10 x 15 mm) were inserted on each mandibular side and fixed with both a titanium implant and an osteosynthetic screw. Three different therapies were tested: (1) xenogenous block alone; (2) xenogenous block, covered with a chemically cross-linked collagen membrane; and (3) autologous blocks, harvested during defect preparation. After 3 months of submerged healing, the miniscrews were removed and replaced by dental implants. Following an additional healing period of 3 months, the animals were sacrificed, and dissected blocks were prepared for histomorphometric analysis. RESULTS: During the primary healing period, three of 12 hemimandibles (six blocks) had to be removed because of severe inflammatory reactions (two xenogenous block sites with collagen membrane, one autologous block site). In general, histologic analysis revealed that xenogenous blocks, used alone or combined with a collagen membrane, exhibited osteoconductive properties on a level equivalent to that of autologous blocks, resulting in means of 50% to 60% of ossification of the blocks. Some parts of the xenograft were encased in soft tissue, partly surrounded by multinuclear giant cells. However, all groups showed obvious signs of bone/graft resorption. CONCLUSIONS: Within the limits of the present study, it was concluded that the examined screwable xenogenous bone block might be a useful scaffold for ridge augmentation procedures. However, the combination of xenogenous blocks with a cross-linked collagen membrane did not appear to improve outcomes.

Comparison of torque measurements and clinical handling of various surgical motors.

PURPOSE: Modern implant dentistry requires the application of torque during various treatment steps. This study investigated seven different surgical motors for the accuracy of the applied torque and their reliability. MATERIALS AND METHODS: The following surgical motors were evaluated: Chiropro 980 (Bienair), INTRAsurg 300 and INTRAsurg 500 (KaVo), Osseocare (Nobel Biocare), Surgic XT (NSK), Elcomed SA-200 C (W and H), and Osseo System (XO Dentalcare). The torque was measured during typical surgical and prosthetic procedures using a special load transfer mechanism for a torque gauge. For each setting, 30 measurements were made and means were calculated. RESULTS: The highest percentage shortfall was 20.5% at a set torque of 11.4 Ncm (absolute deviation of -2.4 Ncm). The highest percentage by which a torque was exceeded was 54.6% (absolute deviation of 5.5 Ncm). The lowest value for absolute shortfall was found to be -5.6 Ncm at a set torque of 45 Ncm. The highest absolute exceeded was 15 Ncm at a set torque of 40 Ncm. Potentially problematic torque values were identified in the low-torque-value setting, as the implant position may be changed if a machine driver applies excessive torque to the first-stage healing screw. In addition, in the indication of immediate loading in the high-set-torque group, torque values above the critical value of 50 Ncm may be unwittingly applied while working with a set torque of 40 Ncm. CONCLUSION: For most of the clinically relevant torque settings, precise values were measured, although a few devices delivered potentially problematic torque values for some of the indications.

Craniomaxillofacial patient-specific CAD/CAM implants based on cone-beam tomography data - A feasibility study.

Customized implants have simplified surgical procedures and have improved patient outcome in craniomaxillofacial surgery. Traditionally, patient-specific data is gathered by conventional computed tomography (CT). However, cone-beam CT (CBCT) can generate a 3D reconstruction of the area of interest with a lower dose of radiation at reduced cost. In this study, we investigated the feasibility of using CBCT data to design and generate customized implants for patients requiring craniomaxillofacial reconstruction. We used CBCT to generate 62 implants for 51 consecutive patients admitted to our department between January 2015 and December 2017. The indications for reconstruction and types of reconstruction were very variable. In all cases, the implants were well fitted and no implant-related complications were detected. Pre-surgical planning was faster and more efficient as we did not have to consult a radiologist. Although CBCT data is more difficult to process than conventional CT data for the implant provider, the clinical advantages are pronounced and we now use CBCT as standard in our department. In conclusion, we have shown that using CBCT to design and manufacture customized implants for reconstruction of the craniomaxillofacial area is feasible and recommend this approach to other departments.

Current concepts in cleft care: A multicenter analysis.

The current surgical techniques used in cleft repair are well established, but different centers use different approaches. To determine the best treatment for patients, a multi-center comparative study is required. In this study, we surveyed all craniofacial departments registered with the German Society of Maxillofacial Surgery to determine which cleft repair techniques are currently in use. Our findings revealed much variation in cleft repair between different centers. Although most centers did use a two-stage approach, the operative techniques and timing of lip and palate closure were different in every center. This shows that a retrospective comparative analysis of patient outcome between the participating centers is not possible and illustrates the need for prospective comparative studies to establish the optimal technique for reconstructive cleft surgery.

Application of an augmented reality tool for maxillary positioning in orthognathic surgery - a feasibility study.

BACKGROUND: An augmented reality tool for computer assisted surgery named X-Scope allows visual tracking of real anatomical structures in superposition with volume rendered CT or MRI scans and thus can be used for navigated translocation of bony segments. METHODS: In a feasibility study X-Scope was used in orthognathic surgery to control the translocation of the maxilla after Le Fort I osteotomy within a bimaxillary procedure. The situation achieved was compared with the pre-operative situation by means of cephalometric analysis on lateral and frontal cephalograms. RESULTS: The technique was successfully utilized in 5 patients. Maxillary positioning using X-Scope was accomplished accurately within a range of 1mm. The tool was used in all cases in addition to the usual intra-operative splints. A stand-alone application without conventional control does not yet seem reasonable. CONCLUSION: Augmented reality tools like X-Scope may be helpful for controlling maxillary translocation in orthognathic surgery. The application to other interventions in cranio-maxillofacial surgery such as Le Fort III osteotomy, fronto-orbital advancement, and cranial vault reshaping or repair may also be considered.

Moving the mandible in orthognathic surgery - A multicenter analysis.

Orthognathic surgery has always been a classical focus of maxillofacial surgery. Since more than 100 years, various surgical techniques for mandibular repositioning have been developed and clinically tested. Since the establishment of plate and screw osteosynthesis, orthognathic surgery became more stable and safe. Nowadays, different surgical methods for mobilising the mandible are existing. This international multicenter analysis (n = 51 hospitals) is providing first evidence based data for the current use of different surgical methods. The dominating techniques were Obwegeser/dal Pont (61%) followed by Hunsuck/Epker (37%) and Perthes/Schlössmann (29%). The main osteosynthesis materials were plates (82%), bicortical screws (23.5%), or a combination of both (5.9%). 47% of all centers reported to use several surgical methods at the same time, depending on the anatomical problem and the surgeon's preference. This shows that different surgical methods seem to work as comparable, safe, and reliable procedures in everydays clinical practise. On this basis, further prospective studies could evaluate possible advantages for our patients.

The current state of facial prosthetics ­ A multicenter analysis.

Even though modern surgical techniques are dominating reconstructive facial procedures, the capability to use facial epitheses for reconstruction is still an important skill for the maxillofacial surgeon. We present an international multicenter analysis to clarify which techniques are used to fixate facial prostheses. We contacted all maxillofacial departments in Germany, Austria, Switzerland and Norway which were registered with the German society for oral and maxillofacial surgery (DGMKG). These centers were asked via electronical mail to provide information on the type of epithesis fixation systems currently in use. The return rate from 58 departments was 43.1% (n = 25). Overall, implant fixation was the preferred fixation system (92%). Plates were the second most common fixation technique (32%). No centers reported the standard use of non-invasive fixation techniques for permanent epithesis fixation. The main retention systems in use were magnets (24/25), other retention systems are used much less often. The current preferred fixation technique for facial epitheses consists of implant-based, magnet-fixated epitheses. For nasal prostheses, a plate-based, magnet-fixated system is often used.

Preliminary results of standardized occipital advancement in the treatment of lambdoid synostosis.

INTRODUCTION: Lambdoid synostosis can be found unilaterally, bilaterally or in combination with other forms of craniosynostosis. Based on the concept of frontoorbital advancement, we used the occipital advancement in order to correct unilateral or bilateral lambdoid synostosis. METHODS: The standardized technique consists of transverse osteotomies, removal, remodelling and advancement of the occipital region. RESULTS: Standardized occipital advancement was performed in 21 patients at a multidisciplinary craniofacial centre. The surgery was carried out for patients between 5 and 28 months of age. Aesthetically satisfactory skull shape and normalization of the intracranial pressure could be achieved. A major complication in the form of a life-threatening intraoperative haemorrhage occurred in one case. Other complications like infections have not been experienced. CONCLUSION: Standardized occipital advancement allows precise, reproducible and predictable positioning of the segments. Artificial 'sutures' are created as a result of the osteotomy. Remodelling leads to a well-proportioned skull shape and posterior advancement leads to an increase in intracranial volume.

Facial basal cell carcinoma with successive metastases to the neck, thyroid gland and lung.

Basal cell carcinoma of the skin is the most common malignancy in the head and neck area. Regional and distant metastases rarely occur with this type of tumour. We report an uncommon case of a sclerodermiform basal cell carcinoma of the facial skin in which metastases developed several years after the primary tumour. The metastases occurred in the soft tissue of the neck, the thyroid gland and the lung. This is the first case of BCC with triple metastases which were histologically confirmed.

Computer-assisted orthognathic surgery: waferless maxillary positioning, versatility, and accuracy of an image-guided visualisation display.

There may well be a shift towards 3-dimensional orthognathic surgery when virtual surgical planning can be applied clinically. We present a computer-assisted protocol that uses surgical navigation supplemented by an interactive image-guided visualisation display (IGVD) to transfer virtual maxillary planning precisely. The aim of this study was to analyse its accuracy and versatility in vivo. The protocol consists of maxillofacial imaging, diagnosis, planning of virtual treatment, and intraoperative surgical transfer using an IGV display. The advantage of the interactive IGV display is that the virtually planned maxilla and its real position can be completely superimposed during operation through a video graphics array (VGA) camera, thereby augmenting the surgeon's 3-dimensional perception. Sixteen adult class III patients were treated with by bimaxillary osteotomy. Seven hard tissue variables were chosen to compare (ΔT1-T0) the virtual maxillary planning (T0) with the postoperative result (T1) using 3-dimensional cephalometry. Clinically acceptable precision for the surgical planning transfer of the maxilla (<0.35 mm) was seen in the anteroposterior and mediolateral angles, and in relation to the skull base (<0.35°), and marginal precision was seen in the orthogonal dimension (<0.64 mm). An interactive IGV display complemented surgical navigation, augmented virtual and real-time reality, and provided a precise technique of waferless stereotactic maxillary positioning, which may offer an alternative approach to the use of arbitrary splints and 2-dimensional orthognathic planning.

Comparison of different autografts for aural cartilage in aesthetic rhinoplasty: is the tragal cartilage graft a viable alternative?

Auricular cartilage is an important source of grafts for various reconstructive procedures such as aesthetic rhinoplasty. The purpose of this investigation was to compare tragal cartilage with auricular cartilage harvested from the concha and scapha, and describe its clinical viability, indications, and morbidity in rhinoplasty. A total of 150 augmentation rhinoplasties with a total of 170 grafts were included. The donor sites were tragus (n=136), concha (n=26), and scapha (n=8). The time needed to harvest the grafts, the donor site morbidity, and the indications for operation were recorded. The anthropometric changes to 4 auricular variables after the cartilage had been harvested were analysed and compared with those on the opposite side in 48 patients using Student's paired t-test. Intraobserver reliability was assessed using Pearson's intraclass correlation. The mean (SD) harvesting time was 27 (8) min for the concha, 4.5 (1.4) min for the tragus, and 5.7 (1.6) min for the scapha. The largest graft was taken from the concha (28×19 mm), followed by the tragus (20×12 mm), and the scapha (18×6 mm). The grafts were placed at the following sites: tip grafts (n=123), columella struts (n=80), shield (n=20), rim (n=17), and dorsal onlay (n=15). Harvesting tragal cartilage is safe, simple, fast, and has a low morbidity, but it can affect the patient's ability to wear earphones. Tragal cartilage is a good alternative for nasal reconstruction if a graft of no longer than 20 mm is required.

Computer-assisted orthognathic surgery: feasibility study using multiple CAD/CAM surgical splints.

OBJECTIVE: We present a virtual planning protocol incorporating a patented 3-surgical splint technique for orthognathic surgery. The purpose of this investigation was to demonstrate the feasibility and validity of the method in vivo. MATERIALS AND METHODS: The protocol consisted of (1) computed tomography (CT) or cone-beam computed tomography (CBCT) maxillofacial imaging, optical scan of articulated dental study models, segmentation, and fusion; (2) diagnosis and virtual treatment planning; (3) computed-assisted design and manufacture (CAD/CAM) of the surgical splints; and (4) intraoperative surgical transfer. Validation of the accuracy of the technique was investigated by applying the protocol to 8 adult class III patients treated with bimaxillary osteotomies. The virtual plan was compared with the postoperative surgical result using image fusion of CT/CBCT dataset by analysis of measurements between hard and soft tissue landmarks relative to reference planes. RESULTS: The virtual planning approach showed clinically acceptable precision for the position of the maxilla (<0.23 mm) and condyle (<0.19 mm), marginal precision for the mandible (<0.33 mm), and low precision for the soft tissue (<2.52 mm). CONCLUSIONS: Virtual diagnosis, planning, and use of a patented CAD/CAM surgical splint technique provides a reliable method that may offer an alternate approach to the use of arbitrary splints and 2-dimensional planning.