Accuracy of Computer-Aided Design/Computer-Aided Manufacturing-Assisted Mandibular Reconstruction With a Fibula Free Flap.

BACKGROUND: The recent increase in computer-aided design and computer-aided manufacturing (CAD/CAM)-assisted surgery has warranted a thorough evaluation of the accuracy of virtual plan execution. Mandibular reconstructions with a fibula free flap were evaluated by comparing the fibular segments postoperatively with the virtual surgical plans. METHODS: This study included computed tomography data for 20 patients (11 males; mean age 61.3 years, range 47-74) that received a mandibular reconstruction with a fibula free flap. Linear distances (superior and inferior borders) of 41 fibula segments and intercoronoid distances were measured. RESULTS: The mean difference was 3.11 ±â€Š2.80 mm for superior borders (range 0.02-12.20 mm), and 2.75 ±â€Š2.61 mm for inferior borders (range 0.22-13.58 mm). The mean intercoronoid difference was 3.57 ±â€Š1.80 mm (range 0.91-6.11 mm). CONCLUSION: This study confirmed the presumed accuracy regarding the use of fibular and mandibular cutting guides. CAD/CAM is an attractive technique which enhances efficiency and assurance during surgery and preoperative planning.

Relapse tendency after BSSO surgery differs between 2D and 3D measurements: A validation study.

Bilateral sagittal split ramus osteotomy (BSSO) surgery is used to correct various dento-skeletal deformities. Clinical outcomes are critically dependent on accurate and proper positioning of skeletal units created by BSSO. Monitoring skeletal changes postoperatively is a major part of follow-up. Between January 2015 and December 2015, 24 patients underwent BSSO surgery without any other segmental osteotomy (mean age, 29.9 ± 14.2 [range, 17-67] years; 18 females). Cephalometric X-rays and cone-beam computed tomography scans were performed 6 weeks and 12 months postoperatively. We compared the position displacement at three mandibular points at both postoperative time points using 2- and 3-dimensional analysis separately and examined the relationship between these methods. Horizontally in at least in 14/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. Vertically in at least in 16/24 patients, the difference between 2-dimensional and 3-dimensional measurements was >1 mm. A scatter plot with orthogonal regression indicated the relationships between the 2-dimensional measurement and the corresponding 3-dimensional measurement in the horizontal and vertical directions. Skeletal relapse with 2-dimensional-measurements differed significantly from the 3-dimensional measurements. There was no evidence of a relationship between the two types of measurements regarding the direction and the location of the landmarks.

Comparison of in vivo cone-beam and multidetector computed tomographic scans by three-dimensional merging software.

In dentomaxillofacial radiology, cone-beam computed tomography (CT) is used to give fast and high-resolution 3-dimensional images of bone with a low dose of radiation. However, its use for quantitative measurement of bone density based on absolute values (Hounsfield units, HU) as in multidetector CT is still controversial. We know of no in vivo study of 3-dimensional merging software that will reliably match identical bone areas of cone-beam and multidetector CT datasets. We studied 19 multidetector, and 19 cone-beam, CT scans of the skull. The two datasets were fused, corresponding points were identified for measurement, and we compared mean density. We used linear regression to analyse the relation between the two different scanning methods, and studied a total of 4180 measurements. The mean time interval between scans was 5.2 (4.7) months. Mean R(2) over all measurements was 0.63 (range 0.22 - 0.79) with a mean internal consistency (Cronbach's α) of 0.86 (range 0.61 - 0.93). The strongest linearity, seen at the left mastoid, was R(2)=0.79 with high internal consistency (Cronbach's α 0.89), and the weakest was at the left zygomatic bone with R(2)=0.22 and Cronbach's α=0.61. Measurements of bone density based on cone-beam and multidetector CT scans generated in vivo showed high and reproducible internal consistency but poor linearity.

SADMFR Guidelines for the Use of Cone-Beam Computed Tomography/Digital Volume Tomography.

In 2011, the first consensus conference on guidelines for the use of cone-beam computed tomography (CBCT) was convened by the Swiss Society of Dentomaxillofacial Radiology (SGDMFR). This conference covered topics of oral and maxillofacial surgery, temporomandibular joint dysfunctions and disorders, and orthodontics. In 2014, a second consensus conference was convened on guidelines for the use of CBCT in endodontics, periodontology, reconstructive dentistry and pediatric dentistry. The guidelines are intended for all dentists in order to facilitate the decision as to when the use of CBCT is justified. As a rule, the use of CBCT is considered restrictive, since radiation protection reasons do not allow its routine use. CBCT should therefore be reserved for complex cases where its application can be expected to provide further information that is relevant to the choice of therapy. In periodontology, sufficient information is usually available from clinical examination and periapical radiographs; in endodontics alternative methods can often be used instead of CBCT; and for implant patients undergoing reconstructive dentistry, CT is of interest for the workflow from implant planning to the superstructure. For pediatric dentistry no application of CBCT is seen for caries diagnosis.

Accuracy of Dental Implant Placement Using CBCT-Derived Mucosa-Supported Stereolithographic Template.

PURPOSE: The aim of the present in vivo study was to evaluate whether a difference exists between the maxilla and the mandible regarding the precision of implant placement utilizing a cone beam computed tomography (CBCT)-derived mucosa-supported stereolithographic (SLA) template. MATERIALS AND METHODS: Eighty implants (44 maxilla, 36 mandible) were placed in 18 fully edentulous jaws (10 maxillas, eight mandibles) using a mucosa-supported SLA surgical template. A voxel-based registration technique was applied to match the postoperative and preoperative CBCT scans. RESULTS: Vertical deviation (p = .026) at the implant hex and angular deviation (p = .0188) were significantly lower in the maxilla than in the mandible. The global linear deviation and lateral deviation at the implant hex were not significantly different. At the implant apex, the average maximum vertical deviation was within 1 mm (0.1-4.6 mm). The average maximum lateral deviation was 1.8 mm (0.9-5.5 mm) in the maxilla and 2.3 mm (0.5-5.5 mm) in the mandible when a 15-mm-long implant was placed. CONCLUSIONS: When using CBCT-derived mucosa-supported SLA templates, clinicians should be aware of differences in the angular deviation of the implants in the mandible and maxilla. The average maximum linear deviation should be considered as a safety margin at the implant apex.

Accuracy of a Dedicated Bone-Supported Surgical Template for Dental Implant Placement with Direct Visual Control.

The aim of this study is to evaluate feasibility and accuracy of dental implant placement utilizing a dedicated bone-supported surgical template. Thirty-eight implants (sixteen in maxilla, twenty-two in mandible) were placed in seven fully edentulous jaws (three maxillae, four mandibles) guided by the designed bone-supported surgical template. A voxel-based registration technique was applied to match pre- and post-operative CBCT scans. The mean angular deviation and mean linear deviation at the implant hex and apex were 6.4 ± 3.7° (0.7°-14.8°), 1.47 ± 0.64 mm (0.5-2.56 mm) and 1.70 ± 1.01 mm (0.71-4.39 mm), respectively. The presented bone-supported surgical template showed acceptable accuracy for clinical use. In return for reduced accuracy, clinicians gain accessibility when using this type of surgical template for both the maxilla and the mandible. This is particularly important in patients with reduced mouth opening.

Healthcare Engineering Defined: A White Paper.

Engineering has been playing an important role in serving and advancing healthcare. The term "Healthcare Engineering" has been used by professional societies, universities, scientific authors, and the healthcare industry for decades. However, the definition of "Healthcare Engineering" remains ambiguous. The purpose of this position paper is to present a definition of Healthcare Engineering as an academic discipline, an area of research, a field of specialty, and a profession. Healthcare Engineering is defined in terms of what it is, who performs it, where it is performed, and how it is performed, including its purpose, scope, topics, synergy, education/training, contributions, and prospects.

SADMFR guidelines for the use of Cone-Beam Computed Tomography/ Digital Volume Tomography.

Cone-Beam Computed Tomography (CBCT) has been introduced in 1998. This radiological imaging procedure has been provided for dentistry and is comparable to computed tomography (CT) in medicine. It is expected that CBCT will have the same success in dental diagnostic imaging as computed tomography had in medicine. Just as CT is responsible for a significant rise in radiation dose to the population from medical X-ray diagnostics, CBCT studies will be accompanied by a significant increase of the dose to our patients by dentistry. Because of the growing concern for an uncritical and consequently rapidly increasing use of CBCT the Swiss Society of Dentomaxillofacial Radiology convened a first consensus conference in 2011 to formulate indications for CBCT, which can be used as guidelines. In this meeting, oral and maxillofacial surgery, orthodontics and temporomandibular joint disorders and diseases were treated and the most important and most experienced users of DVT in these areas were asked to participate. In general, a highly restrictive use of CBCT is required. Justifying main criterion for CBCT application is that additional, therapy-relevant information is expected that should lead to a significant benefit in patient care. All users of CBCT should have completed a structured, high-level training, just like that offered by the Swiss Society of Dentomaxillofacial Radiology.

The accuracy of image-guided navigation for maxillary positioning in bimaxillary surgery.

The aim of our study was to evaluate the accuracy of image-guided maxillary positioning in sagittal, vertical, and mediolateral direction. Between May 2011 and July 2012, 17 patients (11 males, 6 females) underwent bimaxillary surgery with the use of intraoperative surgical navigation. During Le Fort I osteotomy, the Kolibri navigation system was used to measure movement of the maxilla at the edge of the upper central upper incisor in sagittal (buccal surface), vertical (incisor edge), and mediolateral (dental midline) direction. Six weeks after surgery, a postoperative CBCT scan was taken and registered to the preoperative cone-beam computed tomography scan to identify the actual surgical movement of the maxilla. Student 2-tailed paired t test was used to evaluate differences between the measured result from navigation system and actual surgical movement of the maxilla, which were 0.44 ± 0.35 mm (P = 0.82) in the sagittal, 0.50 ± 0.35 mm (P = 0.85) in the vertical, and 0.56 ± 0.36 mm (P = 0.81) in the mediolateral direction. Our finding demonstrates that intraoperative computer navigation is a promising tool for measuring the surgical change of the maxilla in bimaxillary surgery.

Influence of histopathologic factors on pattern of metastasis in squamous cell carcinoma of the head and neck.

OBJECTIVES/HYPOTHESIS: Knowledge of histopathological factors, such as perineural invasion (PNI), extracapsular spread (ECS), angiolymphatic vessel invasion, and conglomerate lymph nodes, in patients with head and neck squamous cell carcinoma is important for appropriate treatment decisions. Given the availability of aggressive therapeutic options with known side effects and burdens for the patient, choosing the correct treatment option is vital. STUDY DESIGN: Retrospective patient database. METHODS: Using a retrospective database of patients treated over a 10-year period, independent prognostic factors for disease-free survival and overall survival were assessed. Univariate analysis was used to identify significant variables, and multivariate Cox regression analysis was used to determine independent prognostic factors. RESULTS: Between January 1, 1999 and December 31, 2009, 291 patients with head and neck squamous cell carcinoma were analyzed to identify influence of histopathological factors on pattern of metastasis. PNI tends to set metastasis locoregional, both in ipsilateral and contralateral lymph nodes. Lymphangiosis eases the way toward ipsilateral lymph node metastasis. ECS spread and hemangiosis demonstrated a significantly higher risk of distant metastasis. With the occurrence of conglomerate lymph nodes, patient data demonstrated a highly significant accumulation of distant metastasis. CONCLUSIONS: Patients with PNI and lymph vessel invasion tend toward locoregional lymph node metastasis on the ipsilateral side of the neck. In cases of PNI, the patient is at risk for a contralateral neck recurrence of the tumor. In patients with ECS, blood vessel invasion, or conglomerate disease, disseminated spread of the disease to distant locations is more likely and has a high negative impact on survival of the patient.

Accuracy of upper jaw positioning with intermediate splint fabrication after virtual planning in bimaxillary orthognathic surgery.

The purpose of the study is to present and discuss a workflow regarding computer-assisted surgical planning for bimaxillary surgery and intermediate splint fabrication. This study describes a protocol starting from wax bite registration to fabrication of the necessary intermediate splint. The procedure is a proof of concept to replace not only the model surgery but also facebow registration and transfer from facebow to articulator. Three different modalities were utilized to obtain this goal: cone beam computed tomography (CBCT), optical dental scanning, and 3-dimensional printing. A universal registration block was designed to register the optical scan of the wax bite to the CBCT data set. Integration of the wax bite avoided problems related to artifacts caused by dental fillings in the occlusal plane of the CBCT scan. Fifteen patients underwent bimaxillary orthognathic surgery. The printed intermediate splint was used during the operation for each patient. A postoperative CBCT scan was taken and registered to the preoperative CBCT scan. The difference between the planned and the actual bony surgical movement at the edge of the upper central incisor was 0.50 ± 0.22 mm in sagittal, 0.57 ± 0.35 mm in vertical, and 0.38 ± 0.35 mm in horizontal direction (midlines). There was no significant difference between the planned and the actual surgical movement in 3 dimensions: sagittal (P = 0.10), vertical (P = 0.69), and horizontal (P = 0.83). In conclusion, under clinical circumstances, the accuracy of the designed intermediate splint satisfied the requirements for bimaxillary surgery.

Evaluation of 3 different registration techniques in image-guided bimaxillary surgery.

Perioperative navigation is an upcoming tool in orthognathic surgery. This study aimed to access the feasibility of the technique and to evaluate the success rate of 3 different registration methods--facial surface registration, anatomic landmark-based registration, and template-based registration. The BrainLab navigation system (BrainLab AG, Feldkirchen, Germany) was used as an additional precision tool for 85 patients who underwent bimaxillary orthognathic surgery from February 2010 to June 2012. Eighteen cases of facial surface-based registration, 63 cases of anatomic landmark-based registration, and 8 cases of template-based registration were analyzed. The overall success rate of facial surface-based registration was 39%, which was significant lower than template-based (100%, P = 0.013) and anatomic landmark-based registration (95%, P < 0.0001). In all cases with successful registration, the further procedure of surgical navigation was performed. The concept of navigation of the maxilla during bimaxillary orthognathic surgery has been proved to be feasible. The registration process is the critical point regarding success of intraoperative navigation. Anatomic landmark-based registration is a reliable technique for image-guided bimaxillary surgery. In contrast, facial surface-based registration is highly unreliable.

Three-dimensional virtual model surgery to fabricate the digital intermediate splint.

Model surgery is the classical requirement for fabricating an intermediate splint for bimaxillary surgery. However, several sources of error complicate the conventional manual technique for making an intermediate splint, and it can be difficult to reposition the cast model of the upper jaw in the desired position. Additionally, the manual procedure is time consuming and requires a lot of laboratory work. Here, we present a technical note on virtual model surgery, a computer-assisted method that combines 3-dimensional cone beam computed tomography (CBCT) of the articulator and an optical scan of the plaster cast models. A registration block is designed to match the detailed occlusal surface scan to the CBCT data. A paired-point-based registration algorithm is utilized to calculate the registration metric and to transfer the scanned plaster cast model of the upper jaw to the desired position. The detailed protocol is described, and one clinical case is presented.

Validation of anatomical landmarks-based registration for image-guided surgery: an in-vitro study.

INTRODUCTION: Perioperative navigation is a recent addition to orthognathic surgery. This study aimed to evaluate the accuracy of anatomical landmarks-based registration. MATERIALS AND METHODS: Eighty-five holes (1.2 mm diameter) were drilled in the surface of a plastic skull model, which was then scanned using a SkyView cone beam computed tomography scanner. DICOM files were imported into BrainLab ENT 3.0.0 to make a surgical plan. Six anatomical points were selected for registration: the infraorbital foramena, the anterior nasal spine, the crown tips of the upper canines, and the mesial contact point of the upper incisors. Each registration was performed five times by two separate observers (10 times total). RESULTS: The mean target registration error (TRE) in the anterior maxillary/zygomatic region was 0.93 ± 0.31 mm (p < 0.001 compared with other anatomical regions). The only statistically significant inter-observer difference of mean TRE was at the zygomatic arch, but was not clinically relevant. CONCLUSION: With six anatomical landmarks used, the mean TRE was clinically acceptable in the maxillary/zygomatic region. This registration technique may be used to access occlusal changes during bimaxillary surgery, but should be used with caution in other anatomical regions of the skull because of the large TRE observed.

Demodicidosis: an uncommon erythema after cranio-maxillofacial surgery.

Demodex mites are commonly found in the healthy population, but the pathogenesis of demodicidosis has still not been clarified, though it is usually found in cases of immune deficiency. A 45-year-old man presented with an unusual outbreak of erythema and swelling 6 months after resection and chemoradiotherapy for a squamous cell carcinoma of the anterior floor of the mouth. The cheek was biopsied and histological examination showed demodicidosis. In cases of erythema with a normal blood cell count and no history of allergy, particularly in patients with reduced immunity, demodicidosis should be considered as a diagnosis and should be confirmed by examination of a biopsy specimen.

Craniofacial landmarks in young children: how reliable are measurements based on 3-dimensional imaging?

INTRODUCTION: Different approaches for 3-dimensional (3D) data acquisition of the facial surface are common nowadays. Meticulous evaluation has proven their level of precision and accuracy. However, the question remains as to which level of craniofacial landmarks, especially in young children, are reliable if identified in 3D images. Potential sources of error, aside from the systems technology itself, need to be identified and addressed. Reliable and unreliable landmarks have to be identified. MATERIALS AND METHODS: The 3dMDface System was used in a clinical setting to evaluate the intraobserver repeatability of 27 craniofacial landmarks in 7 young children between 6 and 18 months of age with a total of 1134 measurements. RESULTS: The handling of the system was mostly unproblematic. The mean 3D repeatability error was 0.82 mm, with a range of 0.26 mm to 2.40 mm, depending on the landmark. Single landmarks that have been shown to be relatively imprecise in 3D analysis could still provide highly accurate data if only 1 of the 3 spatial planes was relevant. There were no statistical differences from 1 patient to another. CONCLUSIONS: Reliability in craniofacial measurements can be achieved by such 3D soft-tissue imaging techniques as the 3dMDface System, but one must always be aware that the degree of precision is strictly dependent on the landmark and axis in question.For further clinical investigations, the degree of reliability for each landmark evaluated must be addressed and taken into account.

The Reliability of a Three-Dimensional Photo System- (3dMDface-) Based Evaluation of the Face in Cleft Lip Infants.

Ample data exists about the high precision of three-dimensional (3D) scanning devices and their data acquisition of the facial surface. However, a question remains regarding which facial landmarks are reliable if identified in 3D images taken under clinical circumstances. Sources of error to be addressed could be technical, user dependent, or patient respectively anatomy related. Based on clinical 3D photos taken with the 3dMDface system, the intra observer repeatability of 27 facial landmarks in six cleft lip (CL) infants and one non-CL infant was evaluated based on a total of over 1,100 measurements. Data acquisition was sometimes challenging but successful in all patients. The mean error was 0.86 mm, with a range of 0.39 mm (Exocanthion) to 2.21 mm (soft gonion). Typically, landmarks provided a small mean error but still showed quite a high variance in measurements, for example, exocanthion from 0.04 mm to 0.93 mm. Vice versa, relatively imprecise landmarks still provide accurate data regarding specific spatial planes. One must be aware of the fact that the degree of precision is dependent on landmarks and spatial planes in question. In clinical investigations, the degree of reliability for landmarks evaluated should be taken into account. Additional reliability can be achieved via multiple measuring.

Microvascular tissue transfer in cleft palate patients: advocacy of the prelaminated radial free forearm flap.

The closure of wide palatal clefts and recurrent oronasal fistulae may be challenging. After repeated failure of conventional techniques, microvascular tissue transfer may be indicated in the closure of such fistulae. Depending on the location and the size of the palatal fistula, different tissues are required to sufficiently close the palatal gaps. A subdivision of common flaps into mucosa, muscular, bony, skin, and fascia flaps was carried out to analyze their suitability for alveolar, hard, and soft palate reconstruction. Furthermore, the bulk of flaps and the length of the vascular pedicle were analyzed to rate the suitability of different flaps for palatal closure. Based on a new classification of oronasal fistulae, all these factors were taken into consideration to introduce a decision guidance of what microvascular flap fits a particular clinical situation. The radial free forearm flap was found to be sufficient in the closure of all classes of oronasal fistulae.

An evaluation of the preoperative hemoglobin level as a prognostic factor for oral squamous cell carcinoma.

BACKGROUND: Hypoxia seems to be an influencing factor for oral squamous cell carcinomas (SCC), and several immunohistochemical markers have been discussed in this regard. The aim of the present study was to evaluate preoperative hemoglobin levels as a prognostic factor for oral SCC. MATERIALS AND METHODS: The files of 287 patients who had been treated for oral SCC between 1999 and 2008 were studied retrospectively. Hemoglobin levels between 1 and 5 days prior to surgical treatment were compared to Tumor (T)- and Nodal (N)- status, local recurrence, and lymph node metastases rate. The minimum follow-up period was 12 months. RESULTS: From a total of 287 patients with oral SCC, 205 (71.4%) were in the normal hemoglobin (Hb) group (female Hb ≥ 12.0 g/dl; male Hb ≥ 13.0 g/dl), 53 (18.5%) in the mild anemia (female Hb = 11.0-11.9 g/dl; male Hb = 11.0-12.9 g/dl), and 29 (10.1%) in the severe anemia group (female & male Hb<11.0 g/dl). Anemia was significant for the development of lymph node metastasis (p = 0.005) as well as for local recurrence (p = 0.001). No significant correlation was found to the initial T status (p = 0.183). CONCLUSION: Our data suggests that an Hb of below 11 g/dl contributes to and is an indicator for a poor prognosis. Consequently, pre-treatment Hb corrections may significantly improve outcome, but further investigations, including blood transfusion/application of erythropoietin due to tumor anemia, independent of intraoperative blood-loss are necessary to ascertain their role in an improved survival.