Simona Mazzoni

Simulation-guided Navigation: A New Approach to Improve Intraoperative Three-dimensional Reproducibility During Orthognathic Surgery

Because of the recent development of three-dimensional technology, computer software is increasingly being used for diagnosis, analysis, data documentation, and surgical planning for orthognathic surgery. Currently, the typical method to reposition jaws in the correct and planned location is based on the use of surgical splints, which have a quite high level of imprecision. The most important differences between planned and achieved maxillary movements are in the vertical and rotational positioning. Several methods have been described for intraoperative maxillary control, but none of these procedures is satisfactory. We present a new method to transfer individualized three-dimensional virtual planning of the patient using a navigation system in the operating room to improve reproducibility of the simulation. We enrolled 10 patients with dentofacial deformities from November 2008 to May 2009. All patients were studied and treated according to the following steps: cone-beam computed tomography data acquisition, virtual simulation of the surgical procedure, surgery with intraoperative navigation, and validation through reproducibility evaluation. We found 86.5% mean preoperative surgical plan reproducibility with the assistance of simulation-guided navigation compared with 80% mean reproducibility obtained in our previous group, in which no intraoperative navigation was performed. According to these results, we can assume that simulation-guided navigation would be a helpful procedure during orthognathic surgery to improve reproducibility of the preoperative virtual surgical planning.

CAD/CAM guided secondary mandibular reconstruction of a discontinuity defect after ablative cancer surgery

A surgical guide is projected to aid the repositioning of the mandibular segments in their original locations, and a reconstruction bone plate is provided to support the fibula free flap. Computer-aided mandibular reconstruction involves three steps: virtual surgical planning, CAD/CAM and rapid-prototyping procedures for the design and manufacture of the customised surgical device and surgery. The duration of the reconstructive phase (<1.5 h intraoperative time) was reduced in comparison with traditional secondary mandibular reconstruction. The bone plate permitted the maximal restoration of the original facial and mandibular contours and the more precise positioning of the residual mandibular ramus in comparison with conventional procedures. No complication was noted during the mean follow-up period of 12 months. The protocol presented in this paper offers some benefits: 1) The virtual environment permitted ideal preoperative planning of mandibular segment repositioning in secondary reconstruction; 2) Intraoperative time was not consumed by approximate and repeated bone plate modelling; 3) Using CT data obtained before primary surgery, the reconstruction bone plate was designed using the original external cortical bone as a template to reproduce the ideal mandibular contour; 4) Prototyped resin models of the bone defect allowed the surgeon to train preoperatively by simulating the surgery.

Oromandibular reconstruction using a fibula osteocutaneous free flap: four different "preplating" techniques.

Background: The aim of oromandibular reconstruction following a partially or fully extended resection is to recreate the normal morphology with a mandibular profile as similar as possible to the original and to restore oral function. Oromandibular reconstruction can be performed with fibula osteocutaneous free flaps combined with the preplating technique. The authors report their experience using the preplating technique for oromandibular reconstruction. Methods: Four different methods can be used to mold the titanium plate that will be used in reconstruction against the existing mandible before resection. The preplating technique was used in 18 patients between 1998 and 2003. In eight patients, the external cortical bone of the mandible was spared by the tumor and the vestibular preplating technique was used. In one patient, the internal cortical bone was unaffected and the lingual preplating technique was used. When the tumor affected both the internal and external cortical bones, the double preplating technique was adopted in eight cases and Luhr’s approach was used in one case. Results: A good cosmetic appearance was obtained through the accurate reconstruction of the inferior mandibular border. Mandible continuity was restored, and the masticatory and oral muscles were anchored to the titanium plate, resulting in good occlusal and functional rehabilitation. Conclusion: The preplating technique combined with a fibula microvascular free flap is a useful, predictable method for oromandibular reconstruction.

Prosthetically guided maxillofacial surgery: evaluation of the accuracy of a surgical guide and custom-made bone plate in oncology patients after mandibular reconstruction.

Background: The aim of the present study was to evaluate the accuracy of prosthetically guided maxillofacial surgery in reconstructing the mandible with a free vascularized flap using custom-made bone plates and a surgical guide to cut the mandible and fibula. Methods: The surgical protocol was applied in a study group of seven consecutive mandibular-reconstructed patients who were compared with a control group treated using the standard preplating technique on stereolithographic models (indirect computer-aided design/computer-aided manufacturing method). The precision of both surgical techniques (prosthetically guided maxillofacial surgery and indirect computer-aided design/computer-aided manufacturing procedure) was evaluated by comparing preoperative and postoperative computed tomographic data and assessment of specific landmarks. Results: With regard to midline deviation, no significant difference was documented between the test and control groups. With regard to mandibular angle shift, only one left angle shift on the lateral plane showed a statistically significant difference between the groups. With regard to angular deviation of the body axis, the data showed a significant difference in the arch deviation. All patients in the control group registered greater than 8 degrees of deviation, determining a facial contracture of the external profile at the lower margin of the mandible. With regard to condylar position, the postoperative condylar position was better in the test group than in the control group, although no significant difference was detected. Conclusions: The new protocol for mandibular reconstruction using computer-aided design/computer-aided manufacturing prosthetically guided maxillofacial surgery to construct custom-made guides and plates may represent a viable method of reproducing the patient’s anatomical contour, giving the surgeon better procedural control and reducing procedure time. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

A CAD/CAM-prototyped anatomical condylar prosthesis connected to a custom-made bone plate to support a fibula free flap

This paper describes a new protocol for mandibular reconstruction. Computer-aided design/computer-aided manufacturing (CAD/CAM) technology was used to manufacture custom-made cutting guides for tumor ablation and reconstructive plates to support fibula free flaps. CT scan data from a patient with an odontogenic keratocyst on the left mandibular ramus were elaborated to produce a virtual surgical plan of mandibular osteotomy in safe tissue for complete ramus resection. The CAD/CAM procedure was used to construct a customized surgical device composed of a cutting guide and a titanium reconstructive bone plate. The cutting guide allowed the surgeon to precisely transfer the virtual planned osteotomy into the surgical environment. The bone plate, including a custom-made anatomical condylar prosthesis, was designed using the outer surface of the healthy side of the mandible to obtain an ideal contour and avoid the bone deformities present on the side affected by the tumor. Operation time was reduced in the demolition and reconstruction phases. Functional and aesthetic outcomes allowed patients to immediately recover their usual appearance and functionality. This new protocol for mandibular reconstruction using CAD/CAM to construct custom-made guides and plates may represent a viable way to reproduce the patient’s anatomical contour, give the surgeon better procedural control, and reduce operation time.

Accuracy of fibular sectioning and insertion into a rapid-prototyped bone plate, for mandibular reconstruction using CAD-CAM technology.

Modern techniques of mandibular reconstruction, such as CAD-CAM technology and rapid prototyping, offer new means by which reconstructive surgery can be planned to optimise aesthetic outcomes and prosthetic rehabilitation. The high degree of accuracy afforded by these approaches is principally attributable to high-precision fibular sectioning and insertion of the bone into a customised bone plate. CAD-CAM mandibular reconstruction procedures using vascularised bone free-flap transfers were performed on 10 patients with benign or malignant neoplasms. Five were not treated with the aid of CAD-CAM technology, and served as the control group. Five were scheduled for maxillofacial surgery using surgical cutting guides and customised bone plates. A generalised linear model for linear measures was used to compare the accuracy of reconstruction between the two groups. A difference, even though not significant, in the lateral shift of the mesial and distal positions of the fibular units was evident between groups. CAD-CAM-generated fibular surgical guides afford improved accuracy when used to restore native anatomy, especially in the context of mandibular arch restoration, and both operating room time and related costs are reduced during fibular sectioning.

The CAD–CAM technique for mandibular reconstruction: An 18 patients oncological case-series

BACKGROUND Modern techniques for mandibular reconstruction, such as CAD-CAM, offer new solutions for planning of reconstructive surgery in relation to the aesthetic outcome and the prosthetic rehabilitation. METHODS CAD-CAM reconstruction procedures using vascularised bone free-flap transfers and surgical guides to cut the mandible and fibula were performed in 18 cases of neoplasms. The planned surgery was used to design and manufacture customised surgical devices. RESULTS The mean follow-up was 12 months. All patients, except one, are alive without disease at the time of writing. Reconstructive microvascular flap survival was 100%. No major or minor microvascular complication occurred. No donor site complication was observed. CONCLUSIONS CAD-CAM technology is a very useful way to obtain the native morphology of the mandible, especially when both bi-dimensional and tri-dimensional defects occur. The reconstruction protocol presented offers several benefits and few disadvantages, which are discussed in the article.

The design and rapid prototyping of surgical guides and bone plates to support iliac free flaps for mandible reconstruction.

Sir:This report describes a novel protocol for the construction of surgical cutting guides and reconstructive titanium bone plates to guide osteotomies according to the preoperative plan and to position and fix an osseous free flap in mandibular reconstruction after cancer removal. Computed tomograp

The Concept of Prosthetically Guided Maxillofacial and Implant Surgery for Maxillary Reconstruction

T he surgical treatment of maxillary tumors in the oral cavity and sinus typically requires a partial or fully extended maxillectomy; the use of virtual planning to restore lost tissues has become popular in reconstructive surgery. A few studies have partially investigated the correlation between the positions of the free graft and oral implants for fixed dental prostheses. Computer-aided design/ computer-aided manufacturing (CAD/CAM) technology has recently opened new frontiers in maxillofacial bone reconstruction, improving the precision of this treatment technique and increasing the success of functional and esthetic outcomes. Its direct application to maxillofacial reconstruction consists of elaborating computerized tomography (CT) data to produce and project a virtual surgical plan, to preoperatively manufacture a customized reconstructive bone plate with the appropriate shape and morphology, and to determine the best position of the fibula free flap to accommodate the final prosthesis. A new methodology for restoring large defects in the maxillofacial region with subsequent intraoral discrepancies between the maxillary arches is proposed using an example case in which the maxillectomy, reconstruction with a fibula free flap and titanium plate, and oral rehabilitation were carried out using CAD-CAM technology.

Chondroma of the mandibular condyle-relapse of a rare benign chondroid tumour after 5 years’ follow-up: case report

Chondroma of the mandibular condyle is rare and its signs and symptoms can mimic those of patients with more common disorders of facial asymmetry or dysfunction of the temporomandibular joint (TMJ). We report a case of chondroma of the mandibular condyle that presented as temporomandibular pain with malocclusion, and which relapsed 5 years after the initial treatment. To our knowledge only 7 cases of chondroma of the mandibular condyle have been reported in the last 70 years. This case is the eighth.