Craniofacial Osteomas: From Diagnosis to Therapy.

An osteoma is a benign bone lesion with no clear pathogenesis, almost exclusive to the craniofacial area. Osteomas show very slow continuous growth, even in adulthood, unlike other bony lesions. Since these lesions are frequently asymptomatic, the diagnosis is usually made by plain radiography or by a computed tomography (CT) scan performed for other reasons. Rarely, the extensive growth could determine aesthetic or functional problems that vary according to different locations. Radiographically, osteomas appear as radiopaque lesions similar to bone cortex, and may determine bone expansion. Cone beam CT is the optimal imaging modality for assessing the relationship between osteomas and adjacent structures, and for surgical planning. The differential diagnosis includes several inflammatory and tumoral pathologies, but the typical craniofacial location may aid in the diagnosis. Due to the benign nature of osteomas, surgical treatment is limited to symptomatic lesions. Radical surgical resection is the gold standard therapy; it is based on a minimally invasive surgical approach with the aim of achieving an optimal cosmetic result. Reconstructive surgery for an osteoma is quite infrequent and reserved for patients with large central osteomas, such as big mandibular or maxillary lesions. In this regard, computer-assisted surgery guarantees better outcomes, providing the possibility of preoperative simulation of demolitive and reconstructive surgery.

Osteosarcoma of the Jaws: A Literature Review.

Osteosarcoma of the jaws (OSJ) is a relatively rare disease, accounting for between 2% and 10% of all cases of osteosarcoma. It is morphologically and radiologically identical to the trunk and extremity variant, but distinct in several crucial aspects. The lesion is characterized by sarcomatous cells which produce a variable amount of osteoid bone. It arises centrally within the bone and can be subdivided into osteoblastic, chondroblastic and fibroblastic subtype, depending on the predominant cell type. Radiographically, these tumors display a spectrum of bone changes from well-demarcated borders to lytic bone destruction with indefinite margins and variable cortical bone erosion or, in some cases, images of sclerotic bone. Therapeutic options for OSJ include surgery, chemotherapy and radiotherapy, which are employed according to age of the patient, histological classification and localization of the tumor. Today, there is no general consensus in the treatment guidelines for the OSJ though surgery represents the key to the treatment. The main prognostic factor deeply influencing the patient's prognosis remains the complete tumor resection with negative surgical margins. The aim of the present review is to describe state of the art regarding diagnostic and surgical treatment aspects of the primary osteosarcoma of the jaws.

Use of CAD-CAM Bridging Mandibular Prosthesis in Osteonecrosis of the Jaw: The Experience of Our School.

Osteonecrosis of the jaw (ONJ) is a disease that affects the jaw. It is mainly related to radiation or bisphosphonates therapy, and the symptoms and signs consist of pain, bone exposure, inflammation of the surrounding soft tissue swelling, and secondary infection or drainage. In the case of advanced disease of the mandibular area, the treatment of choice is mandibular resection and reconstruction. In the present study, we report a case series of patients affected by ONJ and treated with a customised bridging mandibular prosthesis-only technique. From 2016 to 2018, we treated five consecutive patients affected by ONJ: three patients were affected by biphosphonate-related osteonecrosis of the mandible (BRONJ) and two were affected by osteoradionecrosis of the mandible (ORNJ). Three patients needed a soft tissue free flap to permit optimal wound closure, intra- and/or extraorally. All reconstructive procedures were carried out successfully, with no major or minor microvascular complication. The average postoperative follow-up was 24.8 (range 10-41) months. Considering that microvascular bone transfer is a high-risk procedure in BRONJ patients, we can conclude that the positioning of a customised bridging mandibular prosthesis (CBMP), whether or not associated with a microvascular soft tissue transfer, is a safe technique in terms of surgical outcome and feasibility.

Pretreatment tumor volume and tumor sphericity as prognostic factors in patients with oral cavity squamous cell carcinoma.

PURPOSE: This study was designed as a retrospective observational study, focusing on the correlation between the preoperative CT-scan tumor volume, tumor sphericity, and the disease-related prognosis. METHODS: A total of 30 consecutive patients, affected by primary oral cancer, were retrospectively identified from our oral cancer database. The preoperative images (DICOM data) for the study population were uploaded into a modular software package designed to convert patients' medical images into 3D digital models. Multislice interpolation and threshold segmentation tools were used to segment the tumor mass. This was then converted into a 3D mesh and exported in STL format, in order to calculate the corresponding volume. We applied the concept of sphericity - a measurement of how closely the shape of an object approaches that of a mathematically perfect sphere - to the segmented tumor mass. RESULTS: Mean tumor volume was larger in patients with tumor recurrence and/or who had died than in patients who were disease free/alive. Tumor sphericity was influential on clinical outcomes. It appeared to be lower in patients who had tumor recurrence and/or who had died (0.54 ± 0.09 and 0.53 ± 0.05) than in patients who were disease free/alive (0.65 ± 0.07). This difference was statistically significant (p < 0.05). Cumulative recurrence-free survival was 86.2% for patients with a tumor volume lower than the cut-off value. Otherwise, it was 0% for those with a tumor volume higher than the cut-off value (p < 0.01; log rank test). Cumulative recurrence-free survival was 86.3% for patients with a higher sphericity index, compared with 13.6% for those with a lower sphericity index. CONCLUSION: The prognostic model, based on a tridimensional, CT-based characterization of the tumor size, which includes both tumor volume and tumor sphericity, uses readily available information and could be considered when formulating prognoses for patients with oral cancer.

Computer-assisted surgery for reconstruction of complex mandibular defects using osteomyocutaneous microvascular fibular free flaps: Use of a skin paddle-outlining guide for soft-tissue reconstruction. A technical report.

INTRODUCTION: We present our pre-operative virtual planning of complex mandibular reconstruction with a microvascular fibular composite free flap and its harvesting using our novel cutaneous positioning guide based on the perforator vessels for our soft tissue reconstructive surgery. TECHNICAL REPORT: We applied our protocol to 42 consecutive patients needing mandibular composite reconstruction. All patients were preoperatively studied with a CTA scan to evaluate the fibular pattern of vascularization and the perforator vessels three-dimensional path and position. Computer assisted surgery (CAS) was performed: a skin paddle outlining guide (SPOG) was designed to reproduce the shape and area of the planned soft tissue resection. CTA measurements and in vivo findings were compared. After performing the CTA, we classified the viable perforators in High Perforators, Medium Perforators and Low Perforators. The average diameter of the perforator vessels was 3 mm. The average difference between the measurements performed on the CTA and the intra-operative measures was 1, 4 mm. The SPOG was based on calf proximal and distal diameters. The anatomical fitting of the guide was obtained thanks to two customized flanges that embrace circumferentially the proximal and distal portions of the leg. The SPOG encompassed appropriate skin/leg regions, allowing the surgeon to localise the required perforator vessel. CONCLUSIONS: CTA protocol appears to be a valuable approach to asses and virtually simulate composite mandibular reconstructions. The SPOG seems to be a valuable tool to reproduce intra-operatively the planned soft tissue area to be reconstructed.

Navigation-guided resection of maxillary tumors: Can a new volumetric virtual planning method improve outcomes in terms of control of resection margins?

INTRODUCTION: In the present study, our aim was to confirm the role of navigation-guided surgery in reducing the percentage of positive margins in advanced malignant pathologies of the mid-face, by introducing a new volumetric virtual planning method for resection. MATERIALS AND METHODS: Twenty-eight patients were included in this study. Eighteen patients requiring surgery to treat malignant midface tumors were prospectively selected and stratified into two different study groups. Patients enrolled in the Reference Points Resection group (RPR - 10 patients) underwent resection planning using the anatomical landmarks on CT scan; patients enrolled in the Volume Resection group (VR - 8 patients) underwent resection using the new volumetric virtual planning method. The remaining 10 patients (Control group) were treated without the use of a navigation system. RESULTS: In total, 127 margins were pathologically assessed in the RPR group, 75 in the VR group, and 85 in the control group. In the control group, 16% of the margins were positive, while in the RPR group the value was 9%, and in the VR group 1%. CONCLUSIONS: The volumetric tumor resection planning associated to the navigation-guide resection appeared to be an improvement in terms of control of surgical margins in advanced tumors involving the mid-face.

Accuracy of CAD/CAM mandibular reconstruction: A three-dimensional, fully virtual outcome evaluation method.

PURPOSE: Computer-aided design/computer-aided manufacturing (CAD/CAM) methods for mandibular reconstruction have improved both functional and morphological results. We evaluated the accuracy of the CAD/CAM method for mandibular reconstruction and assessed the quantitative and qualitative reproducibility of virtual preoperative planning. MATERIALS AND METHODS: A total of 34 consecutive patients treated with mandibular reconstruction using the CAD/CAM method between January 2011 and October 2017 were included in this study. The accuracy of the reconstruction was assessed using the automated Hausdorff distance function of the simulation software, which set the postoperative mesh as the target. This made it possible to calculate the minimum error, the maximum error, and the mean error for each reconstruction in exactly the same way and with the same settings as the difference between the postoperative mesh and virtual planning. Finally, the coloured quality mapper function was applied to superimposition of the STL files, allowing us to visually render the obtained data on differences between preoperative planning and surgical outcome. RESULTS: The average mean error obtained after performing an accuracy evaluation of our reconstructions was 1 mm (range 0.4-2.46 mm). Based on the colour map areas, the maximum error was located in the symphysis area. The body and ramus areas showed the greatest accuracy in terms of planning reproducibility. CONCLUSION: This is the first study to assess the three-dimensional reproducibility of virtual planning using the CAD/CAM method for mandibular reconstruction, in a homogeneous sample of 34 cases. Our data suggest that CAD/CAM microvascular reconstruction can result in a very high degree of reproducibility. This occurs in complex areas as well as the condylar region and in the case of extensive mandibular reconstructions.

Navigation-guided resection of maxillary tumours: The accuracy of computer-assisted surgery in terms of control of resection margins - A feasibility study.

INTRODUCTION: Surgical treatment of maxillary tumours is often highly complex. The three-dimensional anatomy of the mid-face renders both correct intraoperative orientation and adequate oncological safety difficult to obtain. Recently, computer-assisted techniques and intraoperative navigation have been applied to oncological surgery treating head and neck cancer. However, only a few studies have explored whether preoperative virtual resection planning and intraoperative control of resection margins allow assessment of the surgical margins of the tumour. In our present feasibility study, we developed a protocol for preoperative mapping of tumour margins using computed tomography and/or magnetic resonance imaging, virtual planning of the surgical resection, and intraoperative navigation during actual resection of advanced maxillary tumours. MATERIALS AND METHODS: Twenty patients were included in this feasibility study. We prospectively selected ten patients requiring surgery to treat malignant maxillary tumours. A control group of ten patients was retrospectively selected. The simulation protocol featured the following steps: 1. "Contouring" of the tumour: identification of the tumour and the borders thereof on the axial, sagittal, and coronal planes; 2. Definition of the resection margins by positioning "landmarks" at least 1 cm from the tumour edges on the axial, sagittal, and coronal planes; 3. Simulation of osteotomy lines passing through the landmarks, and evaluation of the bony defects to be reconstructed. Tumour margins were controlled by using a pointer to identify mobilised regions and then checking the overlap between the planned resection (shown on the LCD screen of the navigation system) and the real anatomical situation. RESULTS: A total of 127 margins were pathologically assessed in the test group, and 85 were assessed in the control group. Overall, 9% of surgical margins were positive in the test group, and 16% were positive in the control group (p = 0.0047). A significant difference was apparent in terms of deep margin evaluation: in test patients, 87% of margins were clear; this figure was 75% for the control group (p = 0.0038). No significant difference in either mucosal or bone margin clearance was evident. The preoperative planning errors were <5 mm for 91% of all planned resection margins. CONCLUSION: The navigation-guided resection protocol seems to improve tumour-free margin status in patients with advanced maxillary tumours. Further confirmatory trial, enrolling a larger cohort of patients, is needed to strengthen these preliminary results and advantages of this procedure.