Determining the Effectiveness of Different Reconstruction Method and Mandibular Implants for Fracture in the Mandible

Introduction: Every year, many people suffer from mandibular defects due to various reasons such as trauma or malignant tumors. Various techniques for reconstructing mandibular defects have always been considered by surgeons and maxillofacial specialists to select the best option and achieve the desired results for the patient. In this study, various articles and their techniques for reconstruction of mandibular defects were reviewed and their results were reported. Materials and Methods: The present study is a systematic review study in which the keywords implants, mandibular, trauma, reconstruction of the desired articles in two databases pubmed and science direct from January 1, 2010 to August 31, 2018 And were selected and then examined. Results: 33 articles met the inclusion criteria on which the final review was performed. 17 articles were clinical studies, 9 articles were case reports and 7 articles were reviews. In these 33 studies, various techniques were examined, including the use of free vascularized fibular flap, the use of computer software, and the prototyping technique. Conclusion: Among the existing methods, the use of free vascularized fibular flap has been approved as a widely used and reliable method in various studies, and many researchers believe that this technique is the gold standard for the reconstruction of mandibular defects. The use of computer software was also used as a complementary technique to improve surgical outcomes. Review Article Hassannia and Ghorbanizadeh; JPRI, 33(42B): 237-257, 2021; Article no.JPRI.73051 238


INTRODUCTION
Defects and injuries occures in the maxilla and mandible for various reasons, including trauma, the presence of tumors, osteomyelitis, congenital defects such as hemifacial, microsomia and Pierre Robin sequence [1]. The mandible plays an important role in human life; Protecting the teeth, aiding the mastication process, swallowing, pronunciation and respiration are among the mandibular maps [2]. The mandible is a unique bone in the human body and is very important for several reasons [3]. This bone supports the airway and supports the base of the tongue. Mastication, swallowing and Speeching are done with the help of this bone. Mandible must also withstand a lot of force during the chewing operation [3]. Findings show that this bone receives an average of 4346 Newtons of molar occlusal force [3]. The jawbones are very important in a person's appearance and Esthetic , and many writers and researchers refer to this role of the jaw as "Andy Gump", which refers to a cartoon about smoking in which a person does not have a mandible [3]. In the reconstruction of the jaw, attention should be paid to the individual plans of this organ, and for this reason, the reconstruction of this bone has become very challenging. This bone is also located near the skull bone and its reconstruction complications can have irreversible consequences [3]. Thousands of people need surgery and mandibular reconstruction every year [4][5][6][7]. The first successful mandibular reconstruction was performed in 1976 by Panje et al. [3]. The researchers used groin tissue to reconstruct the mandible. The first hard part used to reconstruct the jaw was made of Vitallium, an alloy of cobalt, chromium and molbidium. This alloy was quickly replaced by stronger and more neutral alloys (5g). Currently, mostly titanium implants are used [2]. Now, maxillofacial reconstructive surgeries involve a wide range of interventions that sometimes lead to soft tissue augmentation and hard tissue restructuring. Reconstruction of oral and maxillofacial defects is recognized as a major challenge for maxillofacial surgeons [1,[8][9][10]. Defects in this area are more common in patients with squamous cell carcinomas [11]. The development of antibiotics in the control of infections, new imaging techniques as well as anesthesia in recent decades has led to major changes in maxillofacial reconstruction [1,8,9]. In this study, different methods of jaw bone regeneration have been studied.

Search and Selection Strategy of Studies
In the present study, in order to find the desired studies in two databases, pubmed and science direct, a search was performed from January 1, 2010 to August 31, 2018 according to the following strategies:

Collecting Data
Two independent judges extracted the information, which included the method used, the advantages and disadvantages of the method and the final result, and published it in tabular form.

Data Analysis
In the present study, the data of selected studies were divided into three groups: Clinical studies, Case report and review. In each group of the year of publication of the article, the type of intervention (method used to repair the damage), the advantages and disadvantages of the method and the final result of the study were extracted and categorized, and since most studies cannot be quantitatively analyzed, The results were reported qualitatively.

Findings
In this study, in the initial search, 202 articles (128 studies in the PubMed database and 74 studies in the Science Direct database) were obtained. In the initial review, 157 studies (119 studies from the PubMed database and 37 studies from the ScienceDirect database) were selected. Were reviewed. Out of 157 studies, 33 articles met the inclusion criteria on which the final study was performed. 17 articles were clinical studies, 9 articles were case reports and 7 articles were reviews.

Clinical Studies
Pototschnig et al.
[12] used free osteofasciocutaneous fibula flap to repair mandibular injury. They studied 104 patients treated with this method and found that using free osteofasciocutaneous fibula flap was the best way to regenerate various mandibular lesions. They believed that using this method included benefits; Optimal blood circulation in the repaired part is smooth, uniform and flexible surface of the skin.
[13] examined the results of using a zygomatic mandibular implant. They examined 15 patients (9 males and 6 females) with a mean age of 40.2 years (12-68 years) who were treated using this implant. The researchers found that using this implant was a good treatment for mandibular lesions and stressed that it should be used as soon as possible after the lesion to achieve better prognosis.
Ayali and Bilginaylar [14] investigated the biomechanical effects of implant diameter. In this study, they examined three groups. In the first group, edentulous people with mandibular bone with atrophy, in the second group, 3.5 × 11.5 mm implant and in the third group, 11.5 × 4.5 implant were used. In the first and second groups, the highest amount of stress was observed in the condylar neck area and in the third group, the highest level of stress was observed in the symphyseal area.  Amrani et al. [20] evaluated 12 patients who were treated for oral-maxillofacial defects by ramus / coronoid process grafts. The results showed that this method was successful when the ad integrum was reconstructed and there were no defective implants in place. In general, it was found that the use of both the coronoid process of the mandible and the mandibular ramus can be used as a suitable source for ossification.
Gray et al. [21] examined the application of new auxiliary methods made possible by the use of computer software. Virtual Surgical Planning (VSP) and computer-aided design / computeraided manufacturing (CAD / CAM) are some of the methods that Gray et al. Evaluated. In a retrospective study between 2012 and 2016, they selected 13 patients who had been screened with VSP and CAD / CAM before surgery. These methods helped the surgeon locate the incision points as well as prepare models. The results of this study showed that the use of VSP and CAD / CAM before surgery makes the results of the operation more accurate and, of course, safer, and in complex cases such as pediatric surgery helps to reduce the duration of surgery.
Tian et al. [22] examined the effect of a complete digital evaluation to visualize iliac bone graft surgery at the location of the implant in the mandibular bone. In fact, the researchers designed a virtual surgery with different types of digital instruments and compared the results with real surgery results. The results of the study showed that the use of digital surgery increases the predictive power of the treatment team from surgery so they can choose a more consistent and accurate method for surgery. The researchers believed that designing a digital process to visualize surgery could lead to more successful surgery and could be used as a treatment protocol to repair oral-maxillofacial defects.
Xu et al. [23] compared the results of different therapies for the treatment of maxillary ankylosis. They selected 18 patients with maxillofacial aneurysms between 2008 and 2013 and divided them into groups of 10 and 8 patients. In the first group, autogenous coronoid process graft (ACPG) and in the second group, lateral arthroplasty (LAP) were used for treatment. The results showed that compared to ACPG, LAP significantly improved facial pattern and interincisal opening (MIO). The researchers believed that LAP was an effective and practical treatment for maxillary oncology.
Yagihara et al. [24] used a poly (L-lactide) mesh combined with autogenous particulate cancellous bone and marrow to regenerate mandibular lesions. In this study, 62 patients were studied in 8 hospitals. The results of the study showed that this method is an effective and stable method due to its favorable morphology, proper functional restoration and low side effects.
Xie and Sun [25] reviewed the results of using a non-vascularized iliac bone graft to reconstruct mandibular defects. They evaluated treatment outcomes and subsequent complications in 34 patients treated with this method. In the end, they concluded that this method is one of the most important methods of treating mandibular defects.
Nthumba [26] was one of the researchers who examined the results of using osteomuscular dorsal scapular flap in the reconstruction of jaw defects. He examined 8 patients with various mandibular defects treated with this method and concluded that this method could be a good choice for mandibular reconstruction, especially in cases where vascular injuries prevent Tissue transfer is free and also in cases where the source of free tissue supply is limited. This method can also be used as a secondary option in cases where free tissue transfer does not have the desired result.
Rana et al. [27] believed that the simplicity of the procedure, maintaining the beauty and healthy function of the face with the least complications in the tissue donor area are the minimum requirements for a good reconstruction. The researchers conducted a study to evaluate the results of bone grafts from different areas. They selected 178 patients with mandibular defects and evaluated their postoperative outcomes. The results of this study showed that autogenous bone grafts are a suitable method for mandibular reconstruction and free vascularized fibular flap should be considered as the first choice in reconstruction of maxillary defects.
Matsuo et al. [28] investigated the use of particulate cancellous bone and marrow (PCBM), platelet-rich plasma (PRP). In a retrospective study, the researchers enrolled 18 patients who had their jaws reconstructed using PCBM and PRP, and analyzed their clinical data. Other cases, there was no significant difference between the two methods. They believed that both methods were safe and reliable and could be used in cases of mandibular defects due to benign tumors and trauma.
The results of 17 clinical studies in the field of reconstruction of mandibular defects show that different methods have been studied and most of them have been introduced as reliable and safe methods. What is remarkable is that the use of free vascularized fibular flap as a desirable and common method has been confirmed by most studies. The coronoid process is also known as a method that has good results in combination with other methods. Studies in recent years have shown a tendency to use computer technology and software to help surgeons design 3D images, perform virtual surgeries, and predict outcome and visualize clinical conditions. It becomes. The results of these studies also show that computer technology and software can help the process of reconstruction of jaw defects and facilitate the working conditions for the surgeon. These results can be seen in Table 1.

Case report studies
D'Amato et al. [29] reconstructed mandibular defects using the bone slat technique. They examined the clinical manifestations, quantity and quality of reconstructed bone, as well as the condition of blood vessels. In this study, a 52year-old patient with a bone defect in the mandible was selected. The results showed that bone strengthening using this technique created the ideal volume of hard bone and soft tissue and provided suitable conditions for implant placement.
Bäumer et al. [30] studied the results of replacing anterior teeth in the mandible with implantsupported crowns. The results showed that the interdental soft tissue was significantly regenerated.
Deshraj and Ghanshyam [31] used flapless implant placement to reconstruct mandibular defects. The results showed that the use of this technique reduced trauma, reduced recovery time, less pain, reduced infection rate, and also improved patient satisfaction and inflammation due to the presence of sufficient arteries. These researchers consider the quality and quantity of hard and soft tissue as the limitation of this surgical method.
Cho-Lee et al. [32] used free vascularized fibula flap to reconstruct mandibular defects in a patient. After examining the clinical evidence and measuring bone indices, the researchers found that the vertical height of the bone remained stable without any complications, and stated that this method is an reliable method for maxillofacial surgery for implant placement. 1 Free osteofasciocutaneous fibula flap The wide cortical bone and the relative constant anatomy, the long pedicle, flat, uniform and sufficient large and pliable skin island, as well as the good blood circulation also by massive modelling of the skin and bone part.

Not reported
The utilisation of the free osteofasciocutaneous fibula flap is the best possible therapy for these difficult composite reconstructions. [12] 2 zygomatic mandibular implant The zygomatic implant is an excellent immediate loading option for mandibular dental rehabilitation among patients with mandibular defects. We could not detect any statistically significant differences in clinical data between the 2 groups, except for the timing of reconstruction. There were postoperative complications such as wound dehiscence and tray exposure, as well as infection of the reconstructed bone. The overall complication rate of the recipient sites in the intraoral group was 30% (3 of 10), whereas in the extraoral group, it was 0%. However, satisfactory bone formation was seen in all cases in the intraoral group (100% [10 of 10]) but only 87.5% (7 of 8) in the extraoral group Not reported using a tray with PCBM and PRP is a safe and reliable method for cases of benign tumor and trauma, even if immediate reconstruction is performed by an intraoral approach [28] Trento et al. [33] used osteogenic distraction technique to reconstruct jaw defects. The researchers believe that this method eliminates the need for bone removal and has better control over increasing bone volume and soft tissue at the same time. The results of this study showed that the use of this method is satisfactory.
Sales et al. [34] reconstructed jaw defects by iliac crest bone graft with planning through rapid prototyping. These researchers believed that this method has many benefits, including; Accurate plate compatibility with bone, shorter surgery time, reduced exposure time under general anesthesia, reduced blood loss, and shorter exposure time to intradermal tissues were noted. In this study, it was found that the duration of surgery was significantly reduced (approximately 50 minutes) and an excellent 2.4 mm reconstruction adaptation, consistent with the findings in the reference kits.
Junli Ma et al. [35] used virtual surgery and three-dimensional (3D) printing technique for fracture reconstruction in the mandible. The results of using this technique in one patient showed that the recovery process proceeded without any problems and the patient was satisfied with the condition of his jaw. The researchers believed that this technology enabled the surgeon to visualize the reconstruction process before surgery, to use it as a guide during surgery, and to perform more precise surgery in less time.
Gravvanis et al. [36] used free osseous flap fibula to reconstruct mandibular defects and free chimeric ALT / functioning vastus lateralis muscle to regenerate muscle in a person injured by a bullet. The results of this surgery showed that the muscles around the mouth were well regenerated and the patient had a normal smile socially and emotionally. The researchers report that a combination of osseous flap fibula with a chimeric functional ALT / Vastus Lateralis flap can be used in severe and complex injuries that also involve cosmetic issues.
Hatamleh et al. [37] used a computer design plus a titanium implant integrated with a selective laser to reconstruct mandibular defects in a 26year-old man who had a deformity of the left mandible due to trauma. This patient showed satisfactory results of the combination of these two methods and it was found that computer design can assist in clinical interventions in the reconstruction process and increase their effectiveness [37].
Review of 9 case reports was another part of the present study. In these 9 articles, 9 different techniques in mandibular reconstruction in each patient have been studied and the results have been reported. Patients ranged in age from 26 to 52 years. These studies also used sharp computer design, the results of which were satisfactory, and the researchers of these studies emphasized that the computer can be of great help to the surgeon. The use of Free Flaps was also introduced as a reliable method and its effectiveness in reconstructing mandibular defects was confirmed. Prototyping was also a regenerative technique for which researchers cited many benefits. They believed that using prototyping reduced surgery time, reduced patient blood loss, reduced anesthesia time, and reduced healing time, and that plaque formed with bone. It is more compatible. Osteogenic distraction was another technique used. The results of using this method in the patient showed that the need for bone removal is eliminated and there is better control over the increase in bone volume and soft tissue. Bone slat was also one of the techniques used to create the ideal volume for implant placement. These results are shown in Table 2.

Review studies
Divi et al. [38] in a review study discussed new tools and methods of mandibular reconstruction and their evolution process. In this article, they state that the use of Computer-aided design (CAD) can help the surgeon a lot and increase their control over the surgical process and increase the surgeon's creativity.  Virtual surgical planning combined with 3D printing technology enables surgeon to visualize the reduction process preoperatively and guide intraoperative reduction, making the reduction less time consuming and more precise. 3D-printed titanium mesh tray can provide more satisfactory esthetic outcomes in treating complex comminuted mandibular fractures Not reported The healing process was uneventful, and the patient was satisfied with the mandible contour [35] 8 A single stage reconstruction with two free flaps was planned; a free fibula osseous flap to reconstruct the mandibular defect, and a free chimeric The one skin paddle of the chimeric flap reconstructed the buccomandibular/suborbital zones of the cheek, and the other the lining of the mouth. The functional muscle provided reanimation of the corner of the mouth by coapting  Table 3. Review studies about mandibular reconstruction methods

Row
Reconstruction method / Objective Advantages of the method Disadvantages of the method Study (references) 1 highlight many of these relatively newer tools and discuss their evolving role in mandibular reconstruction.
The use of CAD has allowed for earlier dental rehabilitation by more accurately modeling the expected position of the bone grafts, determining the position of implants, and guiding the design of the prosthesis. Additive manufacturing gives surgeons an unprecedented level of control in designing plates allowing for new creative designs.
These new technologies will be important in the next stage of mandibular reconstruction as tissue engineering begins to play a more prominent role Not reported [38] 2 discuss classification and approach to reconstruction of mandibular defects This review examines the current literature on functional outcomes of lateral mandibular reconstruction and presents an algorithm on selecting an optimal reconstructive choice for patients with lateral mandibular defects resulting from oncologic ablative surgery or traum Depending on the predominance of the soft-tissue or bony components of the defect, with consideration of the patient's characteristics and functional and aesthetic goals, the surgeon can wisely select from these reconstructive possibilities The test for overall effect showed that the difference between the procedures did not significantly affect the incidence of postoperative complications (P = 0.21), with RR 0.79 (95% CI 0.54-1.14).

Not reported [44]
Oliveira et al. [42] in a systematic review study examined how to use three-dimensional plates in the reconstruction of mandibular defects. The results of this systematic review showed that the success rate of using 3D plates is high compared to other stabilization methods and the use of this method was recommended by these researchers.
Moura et al. [43] reviewed the scientific evidence to evaluate the results of using non-vascularized bone grafts to reconstruct mandibular defects.
They wanted to answer the question, is there any scientific evidence to support this technique? The results of this study indicate that although more clinical studies are needed for better scientific citation, but according to the study, the success rate of non-vascularized bone grafting was 87.6%. It has also been pointed out that if the mandibular defects are due to malignant tumors and radiotherapy is usually used in these cases, the success rate of non-vascularized bone grafting is greatly reduced, so in these cases a method Not optional.
Chrcanovic [44] designed and conducted a review study to compare the clinical results of locking and non-locking fixation plates in mandibular fractures. Findings showed that postoperative clinical results were not significantly different between the two methods (P = 0.21), with RR 0.79 (95% CI 0.54-1.14).
In this study, 7 review articles were reviewed, two of which dealt with the use of computers in mandibular surgery. These two articles reviewed the functions of computer software in visualizing the operation and the result of reconstruction. Both articles emphasized that the use of a computer would help the surgeon to perform the operation more accurately, thus restoring jaw defects with better clinical as well as aesthetic results.
In two studies, the results of non-vascularized bone graft as well as vascularized bone flaps were reviewed. Both methods were introduced by these researchers as effective methods and Vascularized bone flaps were introduced as the gold standard for mandibular reconstruction. However, the researchers' recommendation in using these methods is that; In cases where the jaw defect is due to surgery for malignant tumors and the patient may be exposed to radiation or chemotherapy, the chances of success of these methods are reduced and these reconstruction methods should be used with more consideration.
The use of 3D plates for fixation in mandibular defect surgery was also reviewed by other researchers. The reviewed results of various studies in this field showed that 3D panels are more effective than other similar methods in fixing. Is high and was introduced as an effective method.
One study also found that locking and unlocking fixation plates in mandibular reconstruction did not differ significantly in surgical outcome, and neither was superior to the other.
The results of these seven review articles are that Vascularized bone flaps are an effective method of reconstructing mandibular defects, and the use of computer software can increase surgical success. They experience fewer side effects, have more beautiful faces, and thus have more satisfaction. These results are shown in Table 3.

CONCLUSION
The present study reviewed 33 different articles on the reconstruction of mandibular defects. The mandible is very important in the physical, mental and social health of human beings because in addition to helping respiration, swallowing, chewing has a great role in the beauty of the face and helps to establish social relations by helping speech. Defects in this organ can cause many complications for a person and affect his quality of life. For these reasons, maxillofacial surgeons and specialists in recent years have studied and applied various techniques to repair the defects of this organ, each of which has yielded results. Among the existing methods, the use of free vascularized fibular flap has been approved as a widely used and reliable method in various studies, and many researchers believe that this technique is the gold standard for the reconstruction of mandibular defects. In this method, blood vessels and nerves are delivered to the organ again [ Radial forearm free flap: This flap is mainly used to repair lateral defects and is useful when the goal is to reconstruct the anterior part of the maxilla, areas without mandibular teeth [56] and when the soft tissue needs to be reconstructed [11]. The main disadvantage of using this flap is the defect in the donor part, such as movement disorders and lack of donor part [1]. Scapular free flap: This type of flap is an osteocutaneous flap that is recommended when there are complex defects that involve the skin of the face, mucosa, and bone [57]. This flap accepts dental implants well and has a success rate of 89% [58].
Iliac crest free flap: This flap is the best bone tissue for dental implants [53]. The success rate of using this flap in jaw reconstructions is estimated to be 96% in one study [59].
Non-vascularized bone was another technique that, although not as widely used as free vascularized fibular flap, has been used in some cases and has yielded satisfactory results.
Nonvascularized Bone grafts are used to repair small defects of the mandible and are not useful when the defect is in soft tissue [3]. The main limitation of this method is that it can not be used for patients undergoing radiation therapy. If this method is used in this group of patients, the probability of success is very low and high side effects are usually observed. It should also be noted that most people who need mandibular reconstruction are those who have squamous cell carcinoma and are usually undergoing radiation therapy [3].
The use of computer software was another method studied, which in many cases was used as a complementary technique and improved surgical results. Computer software with threedimensional designs allows the surgeon to visualize a picture of the operation process and its result before the operation, and use this visualization during the surgery and figure out more accurate surgery. For this reason, these techniques are used as an assistant for the surgeon to help him decide on the type and method of reconstruction, as well as to be more careful during surgery.
Prototyping was also used in a limited number of studies, which produced satisfactory results, but the number of these studies is not enough and needs to be addressed more than before.

DECLARATION Amendments
Important protocol amendments post registration will be recorded and included in dissemination.

Support
No sources of support or funding were provided for this review. Authors are based on their self finance.

CONSENT
It is not applicable.

ETHICAL APPROVAL
It is not applicable

ACKNOWLEDGEMENT
The completion of this undertaking could not have been possible without the participation, guiding and assistance of my lovely husband Dr.majid zolfagharikhorshaneh, i would like to express my deep appreciation and indebtedness to him for his endless support.
As well one of our best former professor Dr Joseph Charles Herrero for his wise advice not limited to this work but during all of our professional practice above all, to the great almighty, the author of knowledge and wisdom for his countless love.

COMPETING INTERESTS
Authors have declared that no competing interests exist. of reconstruction for segmental defects of the mandible: a finite element study to assess the optimisation of plate and screw factors.