Reconstruction of Aesthetic Stomatognathic Function After a High-energy Maxillo-orofacial Fracture: a Case Report

Background: High-energy injury patients with head trauma often present with pan-jaw fractures involving loss of teeth and alveolar bone. They experience a signicant decrease in their quality of life due to masticatory disorders, dysarthria, and poor aesthetics. In most cases, they are treated separately by a medical team and a prosthodontist. Moreover, removable dentures provide little satisfaction to the patients. Case presentation: A 29-year-old young woman suffered a high-energy trauma from a fall accident. Following surgery for a jaw fracture, she underwent occlusal reconstruction with osseointegrated implants. The same team performed maxillofacial surgery and prosthetic treatments, and the series of treatment plans included bone grafting and periodontal plastic surgery. Conclusions: The treatment proved successful after more than two years with no signs of peri-implantitis. The patient was highly satised with the results. Early intervention by an oral and maxillofacial surgeon in such patients is essential for a good prognosis. Surgeons and prosthodontists who belong to the same team could complete the treatment with fewer surgical procedures. Furthermore, implant treatment in a patient with oral and maxillofacial fractures might improve aesthetics and function.


Background
Patients who undergo surgery for maxillofacial high-energy trauma (HET) may have facial deformities, bone healing failures, jaw dysfunctions, and malocclusions. Additionally, teeth or alveolar bone defects result in masticatory disorders, dysarthria, and poor aesthetics, delaying the patient's social rehabilitation and signi cantly reducing their postoperative quality of life (QOL). Therefore, it is important to achieve symmetric facial morphology and reliable occlusion reconstruction.
Restoring morphology and function using conventional, removable dentures is challenging. Maxillofacial implants are required for predictable occlusal reconstruction in patients with maxillofacial trauma. The periodontal tissue environment around the implant affects its long-term stability; therefore, a treatment plan involving bone augmentation (alveolar ridge and GBR) and periodontal plastic surgery is required.
Owing to the presence of considerable expectations for the results and the associated process, it is imperative to provide a detailed diagnosis of the condition to maxillofacial and oral surgeons treating HET jaw and occlusal reconstruction.
We present a reconstruction case using a xed prosthesis and osseointegrated implants after maxillofacial trauma due to HET. A bone graft was necessary for dental implantation following the treatment of the jaw fracture. Digital data and setup models were useful for treatment planning. The patient was highly satis ed with the results of the treatment.

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A 29-year-old woman accidentally fell from a height of three oors at a construction site. It took an hour to rescue her from the site, and then she was brought to our emergency department for advanced trauma life support. She was fortunate to have no signi cant intracranial, spinal, or viscerotropic injuries. There were extensive abrasions and a subcutaneous hemorrhage on the face. The right mid-third of the face had recessed, and there was a deep laceration in the lower jaw. The frontal wall of the maxillary sinus was shattered and depressed, and the maxillary dentition was displaced upward and inward, resulting in loss of continuity. Furthermore, the alveolar bone in the upper right 13-17 region presented with a comminuted fracture. Teeth 13, 15, and 16 were located within the fractured area. There was an insular depressed fracture in the right mandible, and the lower right 42-46 dentition were displaced inwards, resulting in an open bite due to early occlusal contacts of the molars. There was a the right inferior alveolar nerve paralysis. (Figs. 1 and 2).
We con rmed the preoperative and postoperative dentition and occlusal conditions before surgery via model surgery and formulated a surgical plan. The rst surgery was performed under general anesthesia, and the dentition was restored as planned. There was no depressed fracture in the zygomatic arch; therefore, the maxillary dental arch, the anterior wall of the maxillary sinus, and the richness of the cheek were restored. The dislocated upper right canine was xed within the dentition, whereas teeth 15 and 16 were abandoned due to the crushed alveolar bone and the maxillary sinus's anterior wall. The maxillary rst premolar had previously been extracted through an orthodontic procedure. The mandibular fracture underwent open reduction and xation using a titanium plate (Figs. 3A, B).
The second surgery for implant removal and maxillary alveolar bone defect atrophy was planned for six months after the rst surgery. Occlusal reconstruction was initiated using digital data and a 3D molded model to envision a xed prosthesis with an osseointegration implant prior to surgery. A cross-sectional computed tomography (CT) scan revealed that the fractured roots of tooth 16 were lodged within the fractured bone and could interfere with placing the dental implant. The alveolar bone in the dentition defect had insu cient height and width for dental implantation. The missing 15 and 16 atypical spaces were recovered using two premolar-shaped prostheses according to the outcomes of diagnostic setup. In The 3D model, it was clear that the alveolar bone in the dentition defect was atrophied and lacked in height and width. (Figs. 4 and 5). An osteotomy of the mentum, from which the titanium plate was removed, was performed (40 × 20 mm); half of it was veneer-grafted with a cortical bone block. The other half was crushed and used to ll the gap to GBR using a titanium mesh (Fig. 6A, B, C). The amount of horizontal bone width created was deemed su cient; additionally, there were no complaints of any abnormal sensations in the anterior teeth in the mandible following bone collection.
The patient underwent a third operation six months later. Due to trauma and the previous surgery, the scar on the tooth defect's alveolar mucosa was visible, and the oral vestibule was narrowed. Non-mobile keratinized mucosa were required in the alveolar ridge mucosa of the dentition. Thus, vestibuloplasty using atelocollagen was performed when the titanium mesh was removed. Two dental implants (Xive dental implants from DENTSPLY, Mannheim GERMANY) were placed on the alveolar ridge after the healing of the mucosa (4 months). A surgical procedure was performed three months later, wherein the attached gingiva at the alveolar crest was extended to the oral vestibular side to obtain keratinized gingiva around the dental implant (Fig. 7).
The provisional restoration was used to harmonize the crown form and gingival morphology, and the nal superstructure was attached about three years after the injury. The patient was fully satis ed with the aesthetic and functional properties. She responded to a maintenance system every 4-6 months and has maintained her oral hygiene with no signs of peri-implantitis (Fig. 8).

Discussion And Conclusion
In severe maxillofacial injury due to HET, prompt cooperation between the primary survey and the specialized departments concerned with the adjacent affected organs is required. In cases where specialized diagnosis and treatment are required to manage systemic and oral/ maxillofacial injuries, it is bene cial to include an oral and maxillofacial during the treatment planning 1) . Multiple maxillofacial injuries result in loss of alveolar mucosa in addition to jaw bone fractures and missing or damaged teeth.
Dental implants are effective in restoring the aesthetic and oral functions 2,3) . However, the reconstruction process requires a long treatment period and many surgeries. There are several advantages of including a maxillofacial surgeon for the occlusal reconstruction during the treatment planning. In the absence of any issues with life support, it is important to consult with adjacent medical specialists, such as brain surgeons, ophthalmologists, and otolaryngologists to start the diagnosis and treatment planning for the middle and lower thirds of the face. The major goals of treating maxillofacial fractures are to restore the midface's symmetry and the mandible's continuity. It is important to follow evidence-based treatment strategies 4) for good results with maxillofacial fracture treatment.
Occlusal reconstruction is the main theme of stomatognathic medicine. It begins 6 months after mandibular fracture following con rmation of the absence of disorders in the temporomandibular joint. It is desirable for this medical team to be able to organically collaborate with the oral surgery team responsible for jawbone fractures, the prosthetic team for restoring the dentition and occlusion, and the periodontal team for improving the periodontal environment. Dental implant treatment aims to match morphological aesthetics with functionality. In order to achieve the maximum effects of the implant in terms of occlusal reconstruction, it is important to assess the condition of the periodontal tissues and place the osseointegrated implant in the appropriate position 5) . Therefore, the use of 3D digital images is useful during treatment planning.
The minimum bone width and height of the alveolar ridge for dental implantation must be > 5 mm and > 10 mm, respectively 6) . Reports on the use of distraction osteogenesis, autologous bone grafting 7) , titanium mesh tray, and iliac particulate cancellous bone and marrow transplantation (Ti-MESH method) 8,9) for bone defects have been published in the literature. The advantage of distraction osteogenesis is that the soft tissue can concurrently be expanded; however, the dynamic treatment period of several months is a major drawback. In the Ti-MESH method, the biggest concern is the surgical invasion of the ilium crest. Expected results may not be obtained due to the titanium mesh's adverse events (tray exposure and increased risk of infection) and remodeling resorption, leading to loss of the graft 10,11) .
Bone grafting is considered optimal for complex and extensive bone loss due to trauma. Autologous bone grafting, which has excellent bone formation ability, is the gold standard for bone regeneration.
Since the donor site's structure and anatomical site may affect the outcome of the bone graft 12) , the recipient site should be closer to the donor if possible. Bone graft planning requires a 10-20% increase in target bone regeneration owing to the resorption of the graft bone. 13) . It has been reported that the amount of the grafted bone absorbed is less in the mandible generated through intramembranous ossi cation than in the iliac crest generated through endochondral ossi cation. 14,15) . The chin bone is highly calci ed, which helps to make an early transition to the mandible 16) . In addition, the cortical bone with its high mineral density is useful for providing the primary stability for the dental implants. We are selected the recipient sites according to the requirements of the donor. In the this case study, the chin's cortical bone was selected because it could be collected from the same surgical eld. The use of chin cortical bone may be useful when grafting a bone to address a few alveolar bone defects.
The keratinized mucosa in the alveolar ridge is often lost along with the alveolar bone following a jaw fracture. Alternatively, a scarred mucosa remains after several surgical procedures. The mobile nonkeratinized mucosa around the dental implant is more likely to cause peri-implantitis 17) . Also, the development of a mucosal scar with poor blood ow is disadvantageous for bone formation. The presence of keratinized mucosa around the dental implants affects the long-term prognosis of the implant treatment 18,19) . Therefore, vestibuloplasty and free gingival grafts to acquire a keratinized mucosa 20) are required. The palatal mucosa or atelocollagen is effective as a recipient of mucosal grafts 21,22) . It is important to ensure that a keratinized mucosa (of 2 mm) is present around the dental implant.
An oral photograph is indispensable because it is impossible to evaluate the soft tissues using X-ray photography or models. At present, it is unclear when the periodontal mucosa should be treated. The apically positioned ap technique is often performed at the same time as the secondary operation.
However, oral mucosal defects after maxilla-orofacial trauma may require mucosal management before implant placement.
For patients with severe facial fractures, strict adherence to a well-established and structured treatment protocol based on surgical experience provides an e cient, appropriate, and successful treatment. Furthermore, superior results for severe traumatic maxilla-orofacial injuries will be achieved if the treatment is combined with e cient occlusal reconstruction.

Consent for publication
The patient provided written informed consent for publication of this case report and any accompanying images.

Availability of data and materials
The datasets generated and/or analyzed during the current study are not publicly available due to inconsistent language expression but are available from the corresponding author upon reasonable request Facial 3DCT image at the time of initial treatment. The right maxilla has a crushed fracture. The upper right canine is dislocated and invaginated, and the upper right second premolar and rst molar are invaded into the crushed bone. The right mandible has a depressed fracture, and the fracture line crosses the mental foramen.

Figure 4
Page 10/10 CT views of the jaws. A. The coronal view shows that the fractured root of the upper right rst molar within the bone is retained. The amount of alveolar bone required for dental implant placement is insu cient in terms of both height and width. B. In the axial view, the length of the alveolar at the tooth loss was atypical. It was revealed that the premolars on the opposite side had 2.5 to 3 teeth.

Figure 8
Results of the treatment. A. Image showing the intraoral frontal view. B. Image showing the intraoral occlusal view. The nal prosthesis was tted according to the treatment plan. The xed implant prosthesis was supported by the keratinized mucosa and maintained in a favorable environment. Two years have passed since the last prosthesis was attached, and no peri-implantitis was observed. C. Orthopantomograph 2 years after the superstructure was attached. No bone resorption was observed around the implant body.