Improving mandibular reconstruction by using topology optimization, patient specific design and additive manufacturing?-A biomechanical comparison against miniplates on human specimen.

In this study, topology optimized, patient specific osteosynthesis plates (TOPOS-implants) are evaluated for the mandibular reconstruction using fibula segments. These shape optimized implants are compared to a standard treatment with miniplates (thickness: 1.0 mm, titanium grade 4) in biomechanical testing using human cadaveric specimen. Mandible and fibula of 21 body donors were used. Geometrical models were created based on automated segmentation of CT-scans of all specimens. All reconstructions, including cutting guides for osteotomy as well as TOPOS-implants, were planned using a custom-made software tool. The TOPOS-implants were produced by electron beam melting (thickness: 1.0 mm, titanium grade 5). The fibula-reconstructed mandibles were tested in static and dynamic testing in a multi-axial test system, which can adapt to the donor anatomy and apply side-specific loads. Static testing was used to confirm mechanical similarity between the reconstruction groups. Force-controlled dynamic testing was performed with a sinusoidal loading between 60 and 240 N (reconstructed side: 30% reduction to consider resected muscles) at 5 Hz for up to 5 · 105 cycles. There was a significant difference between the groups for dynamic testing: All TOPOS-implants stayed intact during all cycles, while miniplate failure occurred after 26.4% of the planned loading (1.32 · 105 ± 1.46 · 105 cycles). Bone fracture occurred in both groups (miniplates: n = 3, TOPOS-implants: n = 2). A correlation between bone failure and cortical bone thickness in mandible angle as well as the number of bicortical screws used was demonstrated. For both groups no screw failure was detected. In conclusion, the topology optimized, patient specific implants showed superior fatigue properties compared to miniplates in mandibular reconstruction. Additionally, the patient specific shape comes with intrinsic guiding properties to support the reconstruction process during surgery. This demonstrates that the combination of additive manufacturing and topology optimization can be beneficial for future maxillofacial surgery.

Strategic use of obturator prostheses for the rehabilitation of oral cancer patients during the COVID-19 pandemic.

During the current pandemic scenario, maxillofacial rehabilitation specialists involved with supportive care in cancer must transform its practice to cope with COVID-19 and improve protocols that could quickly return the oral function of complex cancer patients who cannot wait for surgical complex rehabilitation. This includes the role of the maxillofacial prosthodontist for the rehabilitation of surgically treated patients with maxillary cancers by the means of filling obturator prostheses that are considered an optimal scientific-based strategy to reduce hospital stay with excellent pain control, oral function (speech, swallowing, mastication, and facial esthetics), psychologic and quality of life outcomes for the patients following intraoral cancer resection. Therefore, the aim of this commentary was to bring new lights to the strategic use of obturator prostheses for the rehabilitation of oral cancer patients during the COVID-19 pandemic as well as to present a protocol for managing such cases.

[Expert consensus statement on reconstruction principle for mandibular defect].

Mandibular defect is one of the common defects of maxillofacial region, which can seriously affect the appearance, chew and speech. The ultimate goal of functional reconstruction of mandibular defect is to restore mandibular appearance, denture and occlusal function. Vascularized bone grafting is an effective method for reconstruction of mandibular defect, especially in treatment of large defect. However, functional reconstruction of mandibular defects involves multiple specialties, many technical details and long treatment cycle, resulting in a small proportion of functional reconstruction. To establish standard operating procedures, Society of Oral Maxillofacial Rehabilitation, Chinese Stomatological Association has organized a lot of experts to establish expert consensus statement on reconstruction principle for mandibular defect, referred to standard procedure of indication, preoperative evaluation, choice of donor site, digital technology aided surgery, recommendations of the operation in the process of residual mandibular position fixed, the mandibular body molding denture and common post-operative complications, in order to promote the reconstruction of mandibular defect treatment and improve the quality of reconstruction.

Mandibular Surgical Navigation: An Innovative Guiding Method.

Mandibular osteotomies are usually required to treat craniomaxillofacial disorders. Losses of mandibular continuity result in esthetic and functional deficiency. During the past 30 years, the spread of the computer-assisted surgery techniques, rapid prototyping, and surgical navigation technique has improved the reliability and the outcomes of mandibular resections and reconstructions, by providing realtime feedback to surgeon. Recent studies reported the feasibility and the precision of surgical navigation applied to mandibular surgical resection and reconstruction with fibula flap but none of them describes a method to navigate the jaw allowing its full motility during the operation. To our knowledge, this is the first-time description of such a kind of method to navigate the jaw positioning the dynamic reference frame directly on the mandibular branch to maintain the full mobility of the mandible. The method described in our series has allowed an accurate surgical navigation of the jaw without the need of intermaxillary fixation. This technique could greatly facilitate resection and reconstructive surgical procedures of the jaw while ensuring precision and accuracy. The encouraging results obtained in the present report suggest to further investigate the possibilities of this technique to better define the method and its indications.

Reconstructive considerations in head and neck surgical oncology: United Kingdom National Multidisciplinary Guidelines.

This is the official guideline endorsed by the specialty associations involved in the care of head and neck cancer patients in the UK. The reconstructive needs following ablative surgery for head and neck cancer are unique and require close attention to both form and function. The vast experience accrued with microvascular reconstructive surgery has meant a significant expansion in the options available. This paper discusses the options for reconstruction available following ablative surgery for head and neck cancer and offers recommendations for reconstruction in the various settings. Recommendations • Microsurgical free flap reconstruction should be the primary reconstructive option for most defects of the head and neck that need tissue transfer. (R) • Free flaps should be offered as first choice of reconstruction for all patients needing circumferential pharyngoesophageal reconstruction. (R) • Free flap reconstruction should be offered for patients with class III or higher defects of the maxilla. (R) • Composite free tissue transfer should be offered as first choice to all patients needing mandibular reconstruction. (R) • Patients undergoing salvage total laryngectomy should be offered vascularised flap reconstruction to reduce pharyngocutaneous fistula rates. (R).