In-House Surgeon-Led Virtual Surgical Planning for Maxillofacial Reconstruction.

PURPOSE: Virtual surgical planning (VSP) and custom fabricated cutting guides for maxillofacial reconstruction have been shown to improve the accuracy of bony reconstruction and overall surgical efficiency and decrease the ischemia time. Our aim was to describe an in-house VSP technique for maxillofacial reconstructive procedures. MATERIALS AND METHODS: We used 2 free software applications. 3DSlicer (available at: http://www.3dslicer.org) was used to extract the bones of interest for the recipient and the donor sites from the computed tomography scan's DICOM (digital imaging and communications in medicine) data. The Autodesk Meshmixer (Autodesk Inc, San Rafael, CA) was used to perform VSP and fabrication of the cutting guides. A reconstructed jaw model was printed in-house using a commercially available fused deposition modeling-based desktop 3-dimensional (3D) printer (Qidi Technology, Zhejiang, China) and used to prebend the reconstruction plate. The cutting guides were printed using a commercially available resin-based stereolithography apparatus desktop 3D printer (Form 2, Dental SG Resin; Formlabs, Somerville, MA) to allow for sterilization of the guides. We performed this technique for 19 consecutive patients with maxillofacial benign or malignant tumors requiring microvascular bony reconstruction. We calculated the average time and associated costs using this in-house VSP technique. RESULTS: The technique was found to be simple and repeatable. The average time required for VSP was 158 minutes (2 hours, 38 minutes). The average cost for printing the reconstructed model per case was $5.21 Canadian dollars (CAD), and the average cost for printing the cutting guides per case was $12.80 CAD. CONCLUSIONS: Using this technique, in-house VSP and 3D printing can be performed by the treating surgeon, without an engineering background, within a reasonable period.

Ranitidine Impairs Bone Healing and Implant Osseointegration in Rats' Tibiae.

PURPOSE: Ranitidine has been found to have an impact on bone metabolism by suppressing osteoclastogenesis. We hypothesized that the use of ranitidine would impair bone healing and implant osseointegration. This study investigated the effect of postoperative administration of ranitidine on bone healing and osseointegration in rats. MATERIALS AND METHODS: Twenty-two Sprague-Dawley rats underwent surgery to create a unicortical bone defect in each tibia. A titanium implant was placed on the right tibial defect, whereas the contralateral defect was left unfilled. After surgery, the rats were randomly divided into 2 groups receiving a daily dose of ranitidine or saline solution for 14 days and then euthanized for assessment of bone healing and osseointegration using micro-computed tomography (CT) and histomorphometry. RESULTS: Micro-CT analysis of the bone defect showed a larger bone defect volume in the ranitidine group (0.82 ± 0.13 µL vs 0.66 ± 0.16 µL, P = .034), thinner cortical thickness (0.54 ± 0.07 mm vs 0.63 ± 0.11 mm, P = .026), and less bone regeneration at the defect site (40% ± 12% vs 57% ± 11%, P = .003). Implant-site micro-CT analysis showed less osseointegration in the ranitidine group (34.1% ± 2.7% vs 43.5% ± 2.1%, P = .014), and implant-site histologic analysis showed less medullary (P = .021), cortical (P = .001), and total (P = .003) bone-implant contact and less peri-implant bone volume-tissue volume (P = .002) in the ranitidine group. Histologic analysis for osteoclastic activity showed a lower number of osteoclasts in the ranitidine group (4.8 ± 2.4 mm-2 vs 9.1 ± 2.1 mm-2, P = .026). CONCLUSIONS: The postoperative use of ranitidine impaired bone healing and osseointegration.

A Comprehensive Clinical Care Pathway for Microvascular Maxillofacial Reconstructive Surgery.

PURPOSE: Clinical care pathways (CCPs) for major surgical procedures are less developed. We describe the development of a comprehensive microvascular maxillofacial reconstruction CCP and evaluate the impact. MATERIALS AND METHODS: Our team developed a comprehensive CCP for patients undergoing microvascular free flap reconstruction for benign or malignant tumors. Patient data before (n = 48) and after (n = 47) implementation of the CCP were used to evaluate the impact. Bayesian negative binomial and logistic regression analyses were used to estimate the associations between the CCP and clinical outcomes (length of stay [LOS], readmission to the operating room, and readmission within 3 months of discharge). RESULTS: The average total hospital LOS was high in the pre-CCP group (16.9 days) compared with the post-CCP group (9.8 days). Being in the post-CCP group reduced the LOS in the intensive care unit and surgical ward and reduced the risk of readmission to the operating room. CONCLUSION: Our results underscore the importance of standardized evidence-based patient care through CCPs for complex patient populations.

Nasotracheal Intubation: The Preferred Airway in Oral Cavity Microvascular Reconstructive Surgery?

PURPOSE: We aimed to describe the safety and effectiveness of nasotracheal intubation (NTI) in a cohort of patients undergoing reconstruction of oral cavity defects with free tissue transfer (FTT). MATERIALS AND METHODS: We implemented a retrospective cohort study and enrolled a sample composed of consecutive patients undergoing FTT reconstruction of oral cavity, maxillary, or mandibular defects between 2013 and 2017. These patients were all subject to a newly developed enhanced recovery-after-surgery protocol. The primary outcome measurement was hospital length of stay (LOS). The secondary outcome variables were the duration of mechanical ventilation, intensive care unit (ICU) LOS, need for gastrostomy, and airway-related complications directly associated with either NTI or tracheostomy. Descriptive statistics and a multivariate logistic regression analysis were completed. RESULTS: The sample was composed of 141 patients who had undergone oral cavity FTT for both benign and malignant diseases (NTI, n = 111; tracheostomy, n = 30). Patients managed with NTI had a statistically significantly shorter hospital LOS (8 days vs 15.5 days, P < .0001) and ICU LOS (1 day vs 2 days, P = .0006), as well as a decreased requirement for gastrostomy (17.1% vs 76.7%, P < .0001). Airway-related complications were rare in both the tracheostomy (13.3%) and NTI (3.6%) groups. Multivariate analysis showed that patients undergoing tracheostomy were 3.14 (P = .004) times more likely to have a prolonged hospitalization and 10.4 (P < .0001) times more likely to require a gastrostomy. A sensitivity analysis of only patients with malignant diagnoses had similar statistically significant results. The delayed tracheostomy rate in the NTI group was 3.6%. CONCLUSIONS: To date, this is the largest study to evaluate the use of NTI in patients undergoing oral cavity reconstruction with FTT. Our results suggest that in the appropriate institutional setting, most patients can be safely managed with NTI. This approach results in a decreased hospital LOS and ICU LOS and an earlier resumption of oral intake with less need for gastrostomy.

Two-Dimensional Magnesium Phosphate Nanosheets Form Highly Thixotropic Gels That Up-Regulate Bone Formation.

Hydrogels composed of two-dimensional (2D) nanomaterials have become an important alternative to replace traditional inorganic scaffolds for tissue engineering. Here, we describe a novel nanocrystalline material with 2D morphology that was synthesized by tuning the crystallization of the sodium-magnesium-phosphate system. We discovered that the sodium ion can regulate the precipitation of magnesium phosphate by interacting with the crystal's surface causing a preferential crystal growth that results in 2D morphology. The 2D nanomaterial gave rise to a physical hydrogel that presented extreme thixotropy, injectability, biocompatibility, bioresorption, and long-term stability. The nanocrystalline material was characterized in vitro and in vivo and we discovered that it presented unique biological properties. Magnesium phosphate nanosheets accelerated bone healing and osseointegration by enhancing collagen formation, osteoblasts differentiation, and osteoclasts proliferation through up-regulation of COL1A1, RunX2, ALP, OCN, and OPN. In summary, the 2D magnesium phosphate nanosheets could bring a paradigm shift in the field of minimally invasive orthopedic and craniofacial interventions because it is the only material available that can be injected through high gauge needles into bone defects in order to accelerate bone healing and osseointegration.

Propranolol enhances bone healing and implant osseointegration in rats tibiae.

BACKGROUND: Propranolol, a non-selective ß-blocker widely used to treat cardiovascular conditions, favours bone accrual. Accordingly, we hypothesized that propranolol could be useful for improving bone healing and osseointegration. This in vivo study was designed to investigate the effect of propranolol on bone healing and osseointegration in rats' tibiae. METHODS: On 24 Sprague-Dawley rats, a unicortical defect was created in the right tibial metaphysis of each rat and a custom-made titanium implant was placed in the left tibia. Animals were then assigned into two groups (n = 12, each group) and treated daily with either propranolol (5 mg/kg: subcutaneous) or saline, for 2 weeks. Then, after killing, the volume of the cortical defects (mm3) and the percentages of newly formed bone in the defects, were assessed with microcomputed tomography; bone-implant contact percentage and peri-implant bone volume/tissue volume were assessed by histomorphometry. RESULT: Propranolol-treated rats presented smaller cortical defects (1.56 ± 0.28 mm3 versus 2.04 ± 0.29 mm3 , p < 0.001) with more bone volume/tissue volume (60.6 ± 7.9% versus 41.1 ± 10.2%, p < 0.001) compared to saline-treated rats. Propranolol also enhanced osseointegration as propranolol-treated rats presented higher bone-implant-contact (65.0 ± 13.1% versus 42.5 ± 8.8%, p < 0.001) and peri-implant bone volume/Tissue volume (73.8 ± 10.1% versus 56.9 ± 5.7%, p = 0.007) than saline-treated rats. CONCLUSION: Propranolol enhanced bone healing and implant osseointegration.

Surgical Exposure to Control the Distal Internal Carotid Artery at the Base of the Skull during Carotid Aneurysm Repair.

Extracranial carotid artery aneurysms are rare. Treatment options for these lesions include endovascular interventions, such as coiling and stenting, or surgical reconstruction, such as resection and primary reanastomosis, or interposition bypass grafting. In this report, we describe the surgical technique used to perform surgical repair of an internal carotid artery aneurysm extending up to the base of the skull. Anterior exposure of the infratemporal fossa and distal control of the carotid artery at the level of the carotid canal was achieved through a transcervical approach, performing double mandibular osteotomies with superior reflection of the middle mandibular section.

Development of Neovasculature in Axially Vascularized Calcium Phosphate Cement Scaffolds.

Augmenting the vascular supply to generate new tissues, a crucial aspect in regenerative medicine, has been challenging. Recently, our group showed that calcium phosphate can induce the formation of a functional neo-angiosome without the need for microsurgical arterial anastomosis. This was a preclinical proof of concept for biomaterial-induced luminal sprouting of large-diameter vessels. In this study, we investigated if sprouting was a general response to surgical injury or placement of an inorganic construct around the vessel. Cylindrical biocement scaffolds of differing chemistries were placed around the femoral vein. A contrast agent was used to visualize vessel ingrowth into the scaffolds. Cell populations in the scaffold were mapped using immunohistochemistry. Calcium phosphate scaffolds induced 2.7-3 times greater volume of blood vessels than calcium sulphate or magnesium phosphate scaffolds. Macrophage and vSMC populations were identified that changed spatially and temporally within the scaffold during implantation. NLRP3 inflammasome activation peaked at weeks 2 and 4 and then declined; however, IL-1ß expression was sustained over the course of the experiment. IL-8, a promoter of angiogenesis, was also detected, and together, these responses suggest a role of sterile inflammation. Unexpectedly, the effect was distinct from an injury response as a result of surgical placement and also was not simply a foreign body reaction as a result of placing a rigid bioceramic next to a vein, since, while the materials tested had similar microstructures, only the calcium phosphates tested elicited an angiogenic response. This finding then reveals a potential path towards a new strategy for creating better pro-regenerative biomaterials.

Gastrointestinal stromal tumor with maxillary metastasis: a case report and literature review.

Gastrointestinal stromal tumors (GISTs) form commonly in the stomach, small intestine, colorectum, and esophagus. Metastatic GIST occurs in up to 50% of patients at presentation. The liver and peritoneal cavity are the most common (93%) metastatic sites; head and neck metastases are extremely rare. This report describes a unique case of a 77-year-old man who was diagnosed with a duodenal GIST that had been completely resected 15 years ago. Eleven years after complete resection, he presented with liver metastases and then received multiple lines of systemic therapy and ablative radiotherapy. In 2015, he presented to our oral and maxillofacial surgery department with a left exophytic maxillary mass that filled the left maxillary sinus. Incisional biopsy confirmed metastatic GIST. Further evaluation revealed extensive metastases in the patient's liver, lungs, spleen, abdominal wall, and lymph nodes. After adequate staging, the patient's condition was deemed palliative, and he was referred to the radiation oncology department for palliative treatment of the symptomatic maxillary lesion. To our knowledge, this is the first reported case of maxillary metastasis from a duodenal GIST. Inclusion of GIST in the differential diagnosis of jaw tumors in patients with nonoral malignancies is recommended. The literature on oral metastasis of GIST is reviewed and discussed in this case report.

Skeletal regeneration for segmental bone loss: Vascularised grafts, analogues and surrogates.

Massive segmental bone defects (SBD) are mostly treated by removing the fibula and transplanting it complete with blood supply. While revolutionary 50 years ago, this remains the standard treatment. This review considers different strategies to repair SBD and emerging potential replacements for this highly invasive procedure. Prior to the technical breakthrough of microsurgery, researchers in the 1960s and 1970s had begun to make considerable progress in developing non autologous routes to repairing SBD. While the breaktthrough of vascularised bone transplantation solved the immediate problem of a lack of reliable repair strategies, much of their prior work is still relevant today. We challenge the assumption that mimicry is necessary or likely to be successful and instead point to the utility of quite crude (from a materials technology perspective), approaches. Together there are quite compelling indications that the body can regenerate entire bone segments with few or no exogenous factors. This is important, as there is a limit to how expensive a bone repair can be and still be widely available to all patients since cost restraints within healthcare systems are not likely to diminish in the near future. STATEMENT OF SIGNIFICANCE: This review is significant because it is a multidisciplinary view of several surgeons and scientists as to what is driving improvement in segmental bone defect repair, why many approaches to date have not succeeded and why some quite basic approaches can be as effective as they are. While there are many reviews of the literature of grafting and bone repair the relative lack of substantial improvement and slow rate of progress in clinical translation is often overlooked and we seek to challenge the reader to consider the issue more broadly.

Treatment of Critical-Sized Calvarial Defects in Rats with Preimplanted Transplants.

The local environment and the defect features have made the skull one of the most difficult regions to repair. Finding alternative strategies to repair large cranial defects, thereby avoiding the current limitations of autograft or polymeric and ceramic prostheses constitute an unmet need. In this study, the regeneration of an 8 mm critical-sized calvarial defect treated by autograft or by a monetite scaffold directly placed in the defect or preimplanted (either cranial bone transplant or subcutaneous pocket) and then transplanted within the bone defect is compared. The data reveal that transplantation of preimplanted monetite transplant scaffolds greatly improves the skull vault closure compared to subcutaneously preimplanted or directly placed materials. Autografts, while clearly filling the defect volume with bone appear effective since bone volume inside the defect volume is obviously high, but are not well fused to the skull. The preimplantation site has a large influence on the regeneration of the defect. Transplantation of induced bone inside materials has the potential to reduce the need for autograft harvest without damaging the skeleton. This first demonstration indicates that cranial repair may be possible without recourse to bioactives or cultured cell therapies.

Material-Induced Venosome-Supported Bone Tubes.

The development of alternatives to vascular bone grafts, the current clinical standard for the surgical repair of large segmental bone defects still today represents an unmet medical need. The subcutaneous formation of transplantable bone has been successfully achieved in scaffolds axially perfused by an arteriovenous loop (AVL) and seeded with bone marrow stromal cells or loaded with inductive proteins. Although demonstrating clinical potential, AVL-based approaches involve complex microsurgical techniques and thus are not in widespread use. In this study, 3D-printed microporous bioceramics, loaded with autologous total bone marrow obtained by needle aspiration, are placed around and next to an unoperated femoral vein for 8 weeks to assess the effect of a central flow-through vein on bone formation from marrow in a subcutaneous site. A greater volume of new bone tissue is observed in scaffolds perfused by a central vein compared with the nonperfused negative control. These analyses are confirmed and supplemented by calcified and decalcified histology. This is highly significant as it indicates that transplantable vascularized bone can be grown using dispensable vein and marrow tissue only. This is the first report illustrating the capacity of an intrinsic vascularization by a single vein to support ectopic bone formation from untreated marrow.

Should Live Patient Licensing Examinations in Dentistry Be Discontinued? Two Viewpoints: Viewpoint 1: Alternative Assessment Models Are Not Yet Viable Replacements for Live Patients in Clinical Licensure Exams and Viewpoint 2: Ethical and Patient Care Concerns About Live Patient Exams Require Full Acceptance of Justifiable Alternatives.

This Point/Counterpoint article addresses a long-standing but still-unresolved debate on the advantages and disadvantages of using live patients in dental licensure exams. Two contrasting viewpoints are presented. Viewpoint 1 supports the traditional use of live patients, arguing that other assessment models have not yet been demonstrated to be viable alternatives to the actual treatment of patients in the clinical licensure process. This viewpoint also contends that the use of live patients and inherent variances in live patient treatment represent the realities of daily private practice. Viewpoint 2 argues that the use of live patients in licensure exams needs to be discontinued considering those exams' ethical dilemmas of exposing patients to potential harm, as well as their lack of reliability and validity and limited scope. According to this viewpoint, the current presence of viable alternatives means that the risk of harm inherent in live patient exams can finally be eliminated and those exams replaced with other means to confirm that candidates are qualified for licensure to practice.

Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial.

BACKGROUND: Overdentures retained by a single implant in the midline have arisen as a minimal implant treatment for edentulous mandibles. The success of this treatment depends on the performance of a single stud attachment that is susceptible to wear-related retention loss. Recently developed biomaterials used in attachments may result in better performance of the overdentures, offering minimal retention loss and greater patient satisfaction. These biomaterials include resistant polymeric matrixes and amorphous diamond-like carbon applied on metallic components. The objective of this explanatory mixed-methods study is to compare Novaloc, a novel attachment system with such characteristics, to a traditional alternative for single implants in the mandible of edentate elderly patients. METHODS/DESIGN: We will carry out a randomized cross-over clinical trial comparing Novaloc attachments to Locators for single-implant mandibular overdentures in edentate elderly individuals. Participants will be followed for three months with each attachment type; patient-based, clinical, and economic outcomes will be gathered. A sample of 26 participants is estimated to be required to detect clinically relevant differences in terms of the primary outcome (patient ratings of general satisfaction). Participants will choose which attachment they wish to keep, then be interviewed about their experiences and preferences with a single implant prosthesis and with the two attachments. Data from the quantitative and qualitative assessments will be integrated through a mixed-methods explanatory strategy. A last quantitative assessment will take place after 12 months with the preferred attachment; this latter assessment will enable measurement of the attachments' long-term wear and maintenance requirements. DISCUSSION: Our results will lead to evidence-based recommendations regarding these systems, guiding providers and patients when making decisions on which attachment systems and implant numbers will be most appropriate for individual cases. The recommendation of a specific attachment for elderly edentulous patients may combine positive outcomes from patient perspectives with low cost, good maintenance, and minimal invasiveness. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03126942 . Registered on 13 April 2017.

A Simplified and Systematic Method to Isolate, Culture, and Characterize Multiple Types of Human Dental Stem Cells from a Single Tooth.

This chapter describes a simplified method that allows the systematic isolation of multiple types of dental stem cells such as dental pulp stem cells (DPSC), periodontal ligament stem cells (PDLSC), and stem cells of the apical papilla (SCAP) from a single tooth. Of specific interest is the modified laboratory approach to harvest/retrieve the dental pulp tissue by minimizing trauma to DPSC by continuous irrigation, reduction of frictional heat from the bur rotation, and reduction of the bur contact time with the dentin. Also, the use of a chisel and a mallet will maximize the number of live DPSC for culture. Steps demonstrating the potential for multiple cell differentiation lineages of each type of dental stem cell into either osteocytes, adipocytes, or chondrocytes are described. Flow cytometry, with a detailed strategy for cell gating and analysis, is described to verify characteristic markers of human mesenchymal multipotent stromal cells (MSC) from DPSC, PDLSC, or SCAP for subsequent experiments in cell therapy and in tissue engineering. Overall, this method can be adapted to any laboratory with a general setup for cell culture experiments.