Virtual Surgical Planning for Temporomandibular Joint Reconstruction with Stock TMJ Prostheses: Pilot Study.

The temporomandibular joint (TMJ) is one of the most complex joints in the human anatomy. In advanced degenerative stages, conservative or minimally invasive surgical therapies have failed to restore joint function, and joint replacement with prostheses has been required. Stock prostheses, compared to custom-made prostheses, are much less expensive and require less pre-operative preparation time. Four patients followed for years for temporomandibular dysfunction and previously operated on by arthroscopy or open joint surgery that have been reconstructed with stock TMJ prostheses (STMJP) through virtual surgical planning (VSP) and an STL model with surgical and positioning guides were included. The median follow-up was 15 months; the median number of previous TMJ surgeries was 2. The mean preoperative MIO was 24.6 mm and at longest follow-up was 36.4 mm. The median preoperative TMJ pain score was 8, and the median postoperative TMJ pain was 3. All patients have improved their mandibular function with a clear improvement of their initial situation. In conclusion, we believe that stock TMJ prostheses with virtual surgical planning and surgical guides are a good alternative for TMJ reconstruction at the present time. Nonetheless, prospective and randomized trials are required with long-term follow up to assess their performance and safety.

Versatility of nasolabial flaps in oral cavity reconstructions.

OBJECTIVES: Describe the techniques involved and the results obtained witn nasolabial flaps in small and medium-sized defects of the oral cavity. The procedure is an easy resconstructive option with a high success rate and with very good aesthetic and functional outcomes. STUDY DESIGN: A retrospective analysis of 16 nasolabial flap reconstructions in 15 oncological patients with oral cavity defects undergoing single-stage surgical interventions. We evaluate the tumor type, its location, size, the resective and reconstructive techniques involved, as well as any complications. RESULTS: Out of 15 patients, 9 were male and 6 female, with ages ranging from 60-85 years. The primary tumor was located in the mandibular or maxillary gingiva in 7 patients, the lateral margin of the tongue in 5, the floor of the mouth in 3 and the mandibular symphysis in a single patient. The tumors were of a small to medium size. All patients underwent intraoral resections. In most cases, a cervical dissection was performed. All flaps were completed as single-stage surgical interventions, with 14 unilateral and 2 bilateral procedures. Five patients had received radiotherapy treatment for previous tumors. During the follow up period, which ranged from 4 months to 8 years, only one patient required their flap to be thinned, there were two incidents of surgical wound dehiscence, two hematomas and one orocutaneous fistula, none of which affected the survival of the flap. CONCLUSIONS: The nasolabial flap proves highly versatile in oral cavity reconstructions, coupled with a minimal morbidity of the donor region and good aesthetic and functional results. Its high vascularity allows for cervical dissections to be carried out or even for radiotherapy to be administered prior to it. It is straightforward, safe, and carrying it out as a single-stage intervention makes it the ideal surgical option for small to medium intraoral defects in edentulous patients with other comorbidities.

Predictable dental rehabilitation in maxillomandibular reconstruction with free flaps. The role of implant guided surgery.

The reconstruction of maxillomandibular defects secondary to oral cancer surgery, represent a great challenge for Maxillofacial surgeons. During the last decades the reconstructive surgery has experimented a big advance due to the development of the microsurgical techniques. At present, we are able to reconstruct complex defects using free flaps that provide both soft and bone tissue. Fibula, iliac crest and scapula free flaps have been the three classic options for the maxillomandibular reconstruction owing to the amount of bone that this flaps provide, allowing the posterior dental rehabilitation with implants. Today, our objective it is not only the aesthetic reconstruction, but also the functional reconstruction of the patients enhancing their life quality. Guided implant surgery in free flap reconstructed patients has become an essential tool, helping to define the exact position of the dental implant in the flap. In this way it is possible to look for the areas with better bone conditions, avoiding the osteosynthesis material used to fixate the flap with the native bone and deciding the best biomechanical option, in terms of number and situation of the implants, for the future dental prostheses. In summary, using the guided implant surgery, it is possible to design an exact and predictable dental implant rehabilitation in patients with oral cancer who are reconstructed with free microvascular flap, resulting in an optimal aesthetic and functional result.

Interdisciplinary innovative approach to an aggressive ossifying fibroma case: Integrating 3D surgery and customized reconstruction in maxillofacial and dental care.

Aggressive ossifying fibroma is a benign fibro-osseous disorder characterized by its aggressive behavior, which complicates its management. In this article, we present a case involving the recurrence of this condition in the maxillary region, with orbital and dental involvement, in a patient who had previously undergone surgery and reconstruction with a microvascularized free fibula flap. A multidisciplinary approach involving maxillofacial surgery and dentistry was employed to deliver a customized and entirely satisfactory solution for the patient. The use of 3D surgery was integral to our approach, encompassing pre-surgical digital planning and the transfer of this planning to the operating room via navigation software. Customized surgical cutting guides facilitated precise resection, while a personalized polyether ether ketone (PEEK) prosthesis was utilized for reconstruction of the malar and infraorbital region. Pre-prosthetic computer-aided design/computer-aided manufacturing (CAD/CAM) surgery, along with dental rehabilitation using transepithelial abutments and dental prostheses on a titanium framework, were employed for dental restoration. During the postoperative period, mobility in the reconstructed maxilla was observed due to the loss of support from the initial reconstruction plate. This was addressed by replacing the plate with a custom-made titanium plate, designed to accommodate the location of the transepithelial abutments and prevent disruption of the dental rehabilitation. This case demonstrates the potential of new technologies when applied within the collaborative framework of maxillofacial surgeons and dentists, enabling effective and definitive solutions in complex reconstruction cases. Key words:Aggressive ossifying fibroma; 3D surgery; customized reconstruction; complex dental reconstruction.

Clinical and Pathological Features of Osteosarcomas of the Jaws: A Retrospective Study.

INTRODUCTION: Osteosarcomas of the jaw (OSJs) are rare tumors with distinct characteristics from osteosarcomas affecting other bones. This study aims to analyze the clinical, pathological, and therapeutic characteristics of OSJs. METHODS: A retrospective, descriptive cross-sectional study including patients diagnosed with OSJ registered at the "La Paz" University Hospital, Madrid, was performed. RESULTS: Data of eight patients with a diagnosis of OSJ were obtained during the study period of 22 years (2002-2024). The mean age of the patients was 41 years. The distribution was 1:1 between the maxilla and mandible. Painful inflammation was the most frequent clinical manifestation. Conventional osteoblastic osteosarcoma was the most predominant histological type. Survival rate at 5 years was 50%, which decreased to 25% at 10 years. CONCLUSIONS: OSJs differ from conventional osteosarcomas of long tubular bones. Surgery continues to be the mainstay of treatment. However, more studies are needed through which more standardized protocols can be proposed for adjuvant therapeutic management.

Epithelioid Hemangioendothelioma of Mandibular Gingiva: A Challenging Diagnosis.

Epithelioid hemangioendothelioma (EHE) is a rare neoplasm derived from the vascular endothelium. Although it can occur anywhere in the body, few cases have been described in the oral cavity. We report a 47-year-old woman presenting with a painful ulcerated lesion on the mandibular gingiva, suggestive of a traumatic decubitus ulcer. Histology and immunohistochemistry confirmed the diagnosis of epithelioid hemangioendothelioma. A literature review of EHE of mandibular gingiva was done. Pubmed were searched from 1975 through June 2024 using the following search terms: epithelioid hemangioentothelioma, vascular tumor, oral cavity and mandibular gingiva. Relevant manuscripts were selected and the results were used to update a narrative overview of the diagnosis and management of this entity. We found 38 cases of EHE in the oral cavity, of which 16 were located on the gingiva. Most of them were located on the mandibular gingiva as painless swelling, unlike our case. 70 % of the cases presenting in the mandibular gingiva had bone resorption on imaging. However, only half of those located in the maxillary gingiva had this bone resorption. Only 2 cases located in the mandibular gingiva presented recurrence and 1 of them debuted with nodal metastases after a 7-year follow-up. The clinical and histological diagnosis of EHE is complex and must be confirmed by immunohistochemistry. Upon diagnosing this entity, we should perform an excision with clear margins and conduct long-term follow-up due to the risk of local and distant recurrence. Key words:Epithelioid hemangioendothelioma, Gingival pathologies, Oral cavity, Mandibular Diseases, CD31, Immmunohistochemical markers, Vascular tumor.

Surface scanned 3D designed customized chinstrap for the treatment of intraoral dehiscence in polytraumatized patient. Technical note.

The advent of 3D surgical technology has revolutionized personalized medicine, enabling the development of tailored solutions for individual patients. This technical note presents the application of 3D technology in designing a customized chin guard using flexible 3D resin. The process involves surface scanning the lower facial region of a polytraumatized patient with a structured-light surface 3D scanner, generating a detailed point cloud. The acquired data undergoes meticulous processing within an specific professional software, including erasing unwanted portions, aligning frames, and mesh consolidation. Subsequently, the mesh is exported as an STL file and further refined using a 3D mesh management software. A customized chin support is designed for the specific patient's needs, exported in STL format, and 3D printed using a stereolithography (SLA) printer with Flexible 80A resin. Post-printing procedures involve washing and curing to ensure biocompatibility and optimal mechanical characteristics. The resultant customized chin guard, attached to elastic support straps, offers a precise fit to the patient's anatomy, enhancing comfort and allowing for extended wear. This innovative approach addresses the challenge of surgical intraoral wound dehiscence in a polytraumatized patient, showcasing the potential of 3D technology in personalized medical solutions for complex cases. Key words:Surface scanner, 3D surgery, customized surgery, chinstrap.

Application of 3D technology for the design of a guidewire for deep cervicofacial collections percutaneous management.

Background: This study aims to present a case of deep cervicofacial abscesses and demonstrate the efficacy of CT-guided drainage with a custom-designed puncture guide in a challenging anatomical location. The use of this type of guide is an innovative technique since CAD-CAM technology has not been used for this type of application until now. Material and Methods: A 76-year-old man with persistent facial swelling and trismus underwent surgical drainage initially, but symptoms persisted. A CT-guided transcutaneous approach was planned using a custom-designed positioning guide created with "in-house" 3D technology. The guide was fabricated using Surgical Guide resin, and the patient underwent successful CT-guided drainage. Results: The intervention facilitated precise drainage without damaging critical anatomical structures. The patient exhibited prompt clinical improvement, shortened hospitalization, and favorable aesthetic outcomes. Conclusions: CT-guided drainage, particularly when combined with a custom puncture guide, offers a less invasive alternative for challenging cervicofacial abscesses. This approach proves valuable in reducing procedure duration, minimizing soft tissue trauma, and enhancing preoperative planning, making it especially beneficial for patients with high anesthetic risk or complex anatomical considerations. Key words:Cervical abscess, 3D technology, drainage guide, percutaneous puncture.

Venous malformation differential diagnosis with an odontogenic abscess on a pediatric patient. Case report and review of the literature.

Venous malformations (VMs) are aberrant venous vessel angiogenesis present at birth. However, they can become apparent later in life, debuting in early childhood. This poses a clinical quest for surgeons, dentists, and pediatricians, as they might appear as a compressible mass in the head and neck region, not uncommonly mistaking them for odontogenic abscesses or other soft tissue tumors. The differential diagnosis can be challenging and imaging techniques are often needed. Ultrasounds are extremely useful initially as other diagnostic tools can be potentially harmful in the context of a VM. MRI is key as it provides accurate extension and location information, and allows to plan invasive treatment alternatives if the patient requires it. In this article, we present the case of a 6-year-old girl who was treated by mistake for an infection upon the diagnosis of an incipient odontogenic abscess instead of a venous malformation, and a literature review on VMs. Key words:Venous malformation, odontogenic abscess, differential diagnosis.

DUSP1 and SOX2 expression determine squamous cell carcinoma of the salivary gland progression.

Salivary gland squamous cell carcinomas (SG-SCCs) constitute a rare type of head and neck cancer which is linked to poor prognosis. Due to their low frequency, the molecular mechanisms responsible for their aggressiveness are poorly understood. In this work we studied the role of the phosphatase DUSP1, a negative regulator of MAPK activity, in controlling SG-SCC progression. We generated DUSP1 KO clones in A253 human cells. These clones showed a reduced ability to grow in 2D, self-renew in ECM matrices and to form tumors in immunodeficient mice. This was caused by an overactivation of the stress and apoptosis kinase JNK1/2 in DUSP1-/+ clones. Interestingly, RNAseq analysis revealed that the expression of SOX2, a well-known self-renewal gene was decreased at the mRNA and protein levels in DUSP1-/+ cells. Unexpectedly, CRISPR-KO of SOX2 did not recapitulate DUSP1-/+ phenotype, and SOX2-null cells had an enhanced ability to self-renew and to form tumors in mice. Gene expression analysis demonstrated that SOX2-null cells have a decreased squamous differentiation profile -losing TP63 expression- and an increased migratory phenotype, with an enhanced epithelial to mesenchymal transition signature. In summary, our data indicates that DUSP1 and SOX2 have opposite functions in SG-SCC, being DUSP1 necessary for tumor growth and SOX2 dispensable showing a tumor suppressor function. Our data suggest that the combined expression of SOX2 and DUSP1 could be a useful biomarker to predict progression in patients with SG-SCCs.

Peripheral odontogenic keratocyst. A Case report.

Odontogenic keratocysts (OKCs) are benign cysts arising from the dental lamina and its remnants. They are most commonly located in the posterior body and the ramus of the mandible. The diagnosis of peripheral OKCs (other than intraosseous) are extremely rare and the current literature is limited. The most common location is the gingiva, but mucosal, epidermal, and even intramuscular sites have also been described. Currently 15 cases have been described. The origin and nature of peripheral OKC still remains controversial. The differential diagnosis includes gingival cyst, mucoceles and epidermoid cyst. Soft tissue OKCs have a lower rate of recurrences; 12,5% vs. 62% in intraosseus OKCs. We report a case of a 58-year-old woman with a peripheral OKC, located in the left masticatory space. We performed a review of the existing literature on peripheral odontogenic keratocysts. Key words:Odontogenic keratocysts (OKCs), peripheral keratocyst, mandibular cyst.

Genetic Profile of Arteriovenous Anomalies of the Head and Neck: Implications in Progression and Therapeutic Approaches.

BACKGROUND: Arteriovenous Malformations (AVMs) are complex vascular anomalies that are usually sporadic and can have a variable clinical course. Treatment of AVMs can lead to severe sequeale and require thorough decision-making. There is a lack of standardized treatment protocols showing a growing need for pharmacological targeted therapies, specially in the most severe cases where surgery may not be feasible. Current knowledge in molecular pathways and genetic diagnosis have shed light in the pathophysiology of AVMs, opening possibilities for personalized treatment strategies. METHODS: We performed a retrospective review of patients with head and neck AVMs treated in our department between 2003 and 2021 and performed a complete physical examination and imaging with ultrasound and angio-CT or MRI. Patients underwent genetic testing on AVMs' tissue samples and/or peripheral blood samples. Patients were grouped according to the genetic variant and a correlation between phenotype and genotype was studied. RESULTS: 22 patients with head and neck AVMs were included. We found eight patients with varians in MAP2K1, four patients with pathogenic variants in KRAS, six patients with pathogenic variants in RASA1, one patient with a pathogenic variant in BRAF, one patient with a pathogenic variant in NF1, another patient with a pathogenic variant in CELSR1 and one patient with pathogenic variants in PIK3CA and GNA14. Patients with MAP2K1 variants were the biggest group, with a moderate clinical course. Patients with KRAS mutations showed the most aggressive clinical course and a high rate of recurrence and osteolysis. Patients with RASA1 variants showed a characteristic phenotype with an ipsilateral capillary malformation in the neck. CONCLUSION: We found a correlation between genotype and phenotype in this group of patients. The genetic diagnosis of AVMs is recommended in order to stablish a personalized treatment strategy. Targeted therapies are currently being investigated with promising results and may be recommended in addition to conventional surgical or embolization procedures, specially in the most complex cases. LEVEL OF EVIDENCE: Level IV.

Buccal cheek mucosa solitary fibrous tumor. Case report.

Solitary fibrous tumor (STF) is a mesenchymal tumor that mainly appears in the pleura. Its presence in the oral cavity is very uncommon, being the buccal mucosa the most frequent location. Imaging cannot distinguish this entity between other types of tumors, being histological and immunohistochemical studies essential for its diagnosis. Immunohistochemical stains typically show positive results for CD34, Bcl2, and CD99. Surgical removal with wide margins is the gold standard treatment, requiring a close follow up due to recurrence risk. We present a case report of a solitary fibrous tumor located in the buccal cheek mucosa and the surgical approach. Key words:Solitary fibrous tumor, Buccal mucosa, Intraoral, Immunohistochemical markers.

HPV infection in oral cancer, our experience: prevalence, clinical implications, and current vaccination program in Spain.

Background: Oral cancer is the 11th most common type of cancer in the world, with established major risk factors as tobacco and alcohol, and recently included high-risk human papillomavirus types 16 and 18. HPV types 16 and 18 are the etiologic agents of cervical cancers and a proportion of oropharyngeal cancers. However, the picture of HPV and the clinical implications of oral cancers are not clear with most reports combining oral cancer data with head and neck cancers. It has been confirmed as a favorable prognostic factor in oropharyngeal cancer. However, the prognostic value of HPV in oral squamous cell carcinoma is still unclear. Material and Methods: The main objective of this article is to present the evidence encountered following a bibliographical review of recent publications specifically related to oral cancer and its differences from oropharyngeal cancer. The secondary goals are to present the findings of a five-year retrospective observational study of the prevalence of HPV infection in oral cancer patients treated by the Oral and Maxillofacial Surgery Department at La Paz University Hospital (Madrid, Spain), and finally, we to evaluate and compare our country's HPV prevention program in comparison to other European countries. Results: According to the review of the literature, HPV positive oral squamous cell carcinoma is associated with significantly decreased overall survival and distant control. Bibliographic review suggest HPV infection can be used as a negative prognostic factor in oral squamous cell carcinoma. Conclusions: As regards diagnostic testing for HPV, it should be extended to as many cases of oral cavity squamous cell carcinoma as possible, especially in those with risk factors. The current vaccination program in Spain does not have adequate coverage and is significantly under the level of other European Union countries; it should be expanded and catch-up strategies should be included. Key words:HPV, OSSC, Papillomavirus, oral carcinoma, prevention.

3D designed in-house positioning and cutting guide system for genioplasty surgery. Technical note and case report.

Advances in 3D printing technology have the potential to significantly improve the workflow of maxillofacial surgical planning. In-house fabricated custom positioning and cutting guides allow for intraoperative reproduction of pre-planned osteotomy cuts, which can result in greater surgical accuracy and patient safety while maintaining an acceptable cost-effectiveness ratio. The design and creation of the customized surgical guides is performed in our hospital fab lab, which allows time savings, from an average of 10 days to just 24 hours, and a cost reduction of more than 90%. The process begins with the import of the pre-surgical facial CT scan into 3D software that allows to perform the surgical cuts virtually and the manipulation of the segments. Once the virtual planning of the surgery has been performed, the next step is the creation of the cutting and positioning guides. The final step is the printing of the guides in surgical resin and their sterilization. In addition, post-surgical models can be 3D printed to pre-mold the plates on them, which saves surgical time. The mentoplasty surgery is a simple example of how 3D surgery can be applied to maxillofacial surgery in an efficient way obtaining all the advantages of customized surgery with a limited investment in time and resources. Key words:3Dsurgery, customized, personalized medicine, genioplasty, surgical guides, in house.

Use of surgical bone cement to increase the projection of the nasomaxillary buttress in a case of orthognathic surgery. Technical note.

The soft tissue outcome of the projection at the level of the nasomaxillary buttress is difficult to manage in cases of severe hypoprojection, being orthognathic surgery resolutive at the occlusal level but sometimes insufficient at the level of esthetic outcome. The literature describes the use of alloplastic prostheses and autologous bone grafts, but there are few documented cases of the use of premolded surgical cement for this purpose. The main advantage of the use of bone cement over the alternatives described is its ability to be premolded for customization, low cost, easy availability, speed of preparation and minimal comorbidity. This technical note describes the surgical steps and outcome of the use of surgical bone cement for projection augmentation at this level, including notes on preparation, premolding and fixation. Key words:Orthognathic surgery, maxillary surgery, surgical bone cement, nasomaxillary buttress.

Depth of Invasion: Influence of the Latest TNM Classification on the Prognosis of Clinical Early Stages of Oral Tongue Squamous Cell Carcinoma and Its Association with Other Histological Risk Factors.

BACKGROUND: The American Joint Committee on Cancer (AJCC), in its 8th edition, introduces modifications to the previous TNM classification, incorporating tumour depth of invasion (DOI). The aim of this research is to analyse the prognosis (in terms of disease-free survival and overall survival) of clinical early stage (I and II) squamous cell carcinomas of the oral tongue according to the DOI levels established by the AJCC in its latest TNM classification to assess changes to the T category and global staging system and to evaluate the association between DOI and other histological risk factors. METHODS: A retrospective longitudinal observational study of a series of cases was designed. All patients were treated with upfront surgery at our institution between 2010 and 2019. The variables of interest were defined and classified into four groups: demographic, clinical, histological and evolutive control. Univariate and multivariate analyses were carried out and survival functions were calculated using the Kaplan-Meier method. Statistical significance was established for p values below 0.05. RESULTS: Sixty-one patients were included. The average follow-up time was 47.42 months. Fifteen patients presented a loco-regional relapse (24.59%) and five developed distant disease (8.19%). Twelve patients died (19.67%). Statistically significant differences were observed, with respect to disease-free survival (p = 0.043), but not with respect to overall survival (p = 0.139). A total of 49.1% of the sample upstaged their T category and 29.5% underwent modifications of their global stage. The analysis of the relationship between DOI with other histological variables showed a significant association with the presence of pathological cervical nodes (p = 0.012), perineural invasion (p = 0.004) and tumour differentiation grade (p = 0.034). Multivariate analysis showed association between depth of invasion and perineural invasion. CONCLUSIONS: Depth of invasion is a histological risk factor in early clinical stages of oral tongue squamous cell carcinoma. Depth of invasion impacts negatively on patient prognosis, is capable per se of modifying the T category and the global tumour staging, and is associated with the presence of cervical metastatic disease, perineural invasion and tumoural differentiation grade.

New Technologies for Personalized Medicine in Head and Neck Oncologic and Reconstructive Surgery.

The search for standardized protocols has been a constant concern in Head and Neck Reconstructive Surgery [...].

Mechanisms of Cisplatin Resistance in HPV Negative Head and Neck Squamous Cell Carcinomas.

Head and neck squamous cell carcinomas (HNSCCs) are the eighth most common cancers worldwide. While promising new therapies are emerging, cisplatin-based chemotherapy remains the gold standard for advanced HNSCCs, although most of the patients relapse due to the development of resistance. This review aims to condense the different mechanisms involved in the development of cisplatin resistance in HNSCCs and highlight future perspectives intended to overcome its related complications. Classical resistance mechanisms include drug import and export, DNA repair and oxidative stress control. Emerging research identified the prevalence of these mechanisms in populations of cancer stem cells (CSC), which are the cells mainly contributing to cisplatin resistance. The use of old and new CSC markers has enabled the identification of the characteristics within HNSCC CSCs predisposing them to treatment resistance, such as cell quiescence, increased self-renewal capacity, low reactive oxygen species levels or the acquisition of epithelial to mesenchymal transcriptional programs. In the present review, we will discuss how cell intrinsic and extrinsic cues alter the phenotype of CSCs and how they influence resistance to cisplatin treatment. In addition, we will assess how the stromal composition and the tumor microenvironment affect drug resistance and the acquisition of CSCs' characteristics through a complex interplay between extracellular matrix content as well as immune and non-immune cell characteristics. Finally, we will describe how alterations in epigenetic modifiers or other signaling pathways can alter tumor behavior and cell plasticity to induce chemotherapy resistance. The data generated in recent years open up a wide range of promising strategies to optimize cisplatin therapy, with the potential to personalize HNSCC patient treatment strategies.

Maxillary reconstruction with subperiosteal implants in a cancer patient: A one-year follow-up.

Introduction: To describe a clinical case on cancer patient with ablative tumor surgery, from treatment planning, surgical resection and subsequent implantological rehabilitation. Case Report: A 61-year-old male, diagnosed with a squamous cell carcinoma in the maxilla, requires the removal of the lesion and corresponding oral rehabilitation. However, two surgeries were necessary to rehabilitate the upper jaw. A custom-made prosthesis was fabricated. It was made from sintered titanium using machined subperiosteal implants with a universal external connection. Finally, a milled cobalt- chrome structure was produced and a feldspar ceramic covering was subsequently applied. Conclusions: Rehabilitation using subperiosteal implants may be an alternative tool for complex surgery involving large atrophies or cancer patients who have undergone highly ablative surgery. Key words:Oral rehabilitation, oral cancer, subperiostal implants.