Ameloblastoma is one of the most common tumors of the mandible.Extended mandibular resection can effectively prevent recurrence, but the bone defect after resection directly affects the patients’ facial, chewing and pronunciation functions11. At the same time, it also seriously affects the patients’ daily life and social activities, causing damage to the patients’ psychology. With the maturity of microsurgery technology and the rapid development of digitization12 and 3D printing technology13, iliac bone flap and fibula flap have been widely used in clinical practice as precision medical technology. With the improvement of implant materials and repair technology14, implant repair after bone transplantation has been promoted15. With the transformation of the biomedical model, in addition to the biological indicators such as survival rate and organ function reconstruction, the standard for evaluating the effect of tumor treatment also aims to make patients get better QOL16,17.
Popularization of vascularized iliac bone flap and vascularized fibular flap in clinical practice as precision medical technology
With the development of digital technology and microsurgery technology, fibular flap18 and iliac flap19 are widely used in mandibular defect repair and reconstruction. The study has adopted preoperative digital technology to simulate diseased mandibular resection of all patients. It then has employed mirror technology to restore the shape of the diseased mandible, and undertaken fibula or ilium osteotomy. Afterwards, it has pre-formed the titanium plate on the head mold which was printed by 3D printing technology. During the surgery, the transplanted bone is shaped according to the titanium plate, which greatly shortens the time and improves the accuracy. It also perfectly restores the shape of the mandible and avoids facial collapse and occlusal disorder caused by jaw defect.
The fibular flap is a long tubular bone dominated by cortical bone with sufficient bone mass. The resectable fibula length is 20-26cm. In this group of cases, the length of cut is 16-24cm, which can meet a wide range of bone defects. Moreover, the fibula has a segmental blood supply from the periosteum and an intraosseous blood supply from the nourishing artery, making it plastic and more conforming to the shape of the mandible20,21. However, the height of the fibula is 1.3-1.5cm. Hence the repair of mandibular defects with single-layer fibula faces the problem of crown-to-root ratio imbalance and peri-implantitis22 (Fig. 1), which can only be solved by folded fibula (Fig. 2).The fibula is a type I bone, with almost no cancellous bone except for the cortex and medullary cavity. The whole process of tapping is required to place the implant during the operation.
The iliac bone flap is cancellous bone23. Hence, the ilium cannot be shaped arbitrarily even though the longest donor bone can be up to 14 cm in length. It is not suitable to reconstruct the bone defect with a long span24.Likewise, for lesions involving the condyle and chin, the fibula is recommended for repair. The ilium is a type II-III bone, with large bone fragments. The reconstructed mandible can have a certain height and width, which is more suitable for implant placement (Fig. 3). However, to Compared with the fibula, the ilium’s anti-infection ability in the later stage is not as good as that of the fibula. However, it is relatively concealed and has fewer side effects on the lower extremities25.
Here are precautions in mandibular defect reconstruction: (1) In mandibular resection, it is often necessary to strip or even remove the medial pterygoid and masseter muscles. The reattachment of the masticatory muscle cannot completely restore its biomechanical properties to normal, but will have a certain impact on the mandibular opening and closing movement and chewing efficiency. Therefore, excessive stripping of the masticatory muscles should be avoided. (2) The function of cheek and tongue can improve chewing efficiency by sensing and transporting food. Therefore, under the premise of not violating the principle of no tumor, the buccal and tongue tissues and their sensorimotor nerves should be protected as much as possible. (3)In order to avoid the rotational torsion of the ilium during chewing, it is recommended to choose a four-hole titanium plate rather than the reconstruction plate alone for fixation of the vascularized iliac bone. The fibular flap is recommended to be fixed with a reconstruction plate, while the folded part is recommended to be fixed with a four-hole titanium plate or a lag screw.
Necessity to Implant Restoration
The purpose of repairing and reconstructing mandibular defect is to restore its function and shape, so implant denture repair is an important part of the reconstruction process. Implant restoration can better recover the integrity of the dentition26 as well as patients’ occlusal and masticatory functions, hence improve their QOL27. Here are precautions for Implant Restoration: (1) Partial implants are mostly chosen to support the restoration of fixed dentures. However, when the defect range is large and the number of implants is not enough to support the restoration of fixed dentures, or when the vertical distance is large and the overbite coverage relationship is special, overdentures can be selected for restoration. (2) Screw retention is recommended for the upper porcelain crown. Once peri-implantitis occurs, it is convenient to remove it in time. All patients in this group were retained with screws.(3) Patients must be able to use dental irrigators and interdental brushes for periodontal maintenance. They must return for follow-up visits on time, hence get any possible problems such as peri-implantitis and occlusal interference dealt with in a timely manner. (4) The CBCT should be regularly took to understand the bone resorption around the implant.
Influence of Various Indicators of QOL on Patients
With the development of medical technology, repair and reconstruction after ameloblastoma excision can well restore the patient’s facial shape and chewing function, hence minimize the damage caused by the disease to the patient. However, the psychological impact of disease and surgery on patients lasts for a long time. How to further improve the QOL of patients has become the common goal of doctors and patients28.
EORTC-QLQ-H&N35 mainly investigates various functions of the oral cavity. The patient’s swallowing function was not affected because the lingual and hypoglossal nerves were not damaged during the surgery. Some patients had slurred speech due to tooth loss. however, it gradually returned to normal at 24 months after surgery. The scores diet, social contact, and teeth were highest at 6 months after surgery. The scores gradually returned to preoperative levels as implants were placed and porcelain crowns were restored. The score of the fibula group was slightly lower than that of the ilium group at 24 months after surgery. Patients with single-layer fibula repairing mandibular defects are still afraid to chew on the affected side. Overall, patients were very satisfied with their facial shape, occlusal relationship and chewing function.
OHIP-14 conducted a comprehensive investigation of the patients from the physiological and psychological aspects. After fibula transplantation, although the integrity of the mandible was restored, the loss of teeth and the decline of masticatory function still had a great impact on the patient’s psychology.
All patients had completed dental implant restoration at 24 months after surgery, and their occlusal relationship and masticatory function were gradually restored. The scores of physical impairment, disability and social impairment were significantly lower at 24 months after surgery, with statistically significant difference compared with that at 6 months after surgery. There was no difference between the two groups. It shows that with the implant placement, patients were very satisfied with their facial shape, occlusal relationship and chewing function. Functional limitation was significantly lower in both groups at 24 months after surgery, but remained statistically significant in the ilium group compared with the fibula group. Here are three main reasons for consideration: (1) Patients in the fibula group often involved the ascending ramus of the mandible, and most of the condylar needed to be removed during the surgery. Patients feel discomfort in the joint area after surgery. (2) In the fibula group, a single layer of fibula should be selected to repair the mandibular defect if the defect range is large. It will lead to crown-to-root ratio imbalance and the occurrence of peri-implantitis. (3) The lack of fibula leads to the inability of long-term weight bearing of the lower limb on the affected side, patients will feel tired and weak after the activity. The scores of psychological discomfort and psychological disorder both decreased at 24 months after surgery, without statistically significant difference compared with that at 6 months after surgery. There was no difference between the two groups. Patients remain concerned about tumor recurrence, suggesting that recovery from psychological trauma is much slower than recovery from physical lesion. Foreign scholars have provided psychological counseling to patients with maxillofacial tumors, and achieved good result. Psychological problems in cancer patients have also attracted the attention of clinicians in China. While treating the disease, the patient should be educated on the disease knowledge before surgery to reduce their fear and anxiety about the unknown. Postoperative discomfort in the oral, maxillofacial and lower limbs needed to be diagnosed and treated in a timely manner, and patients were encouraged to actively participate in social activities. At the same time, the survey showed that the encouragement and support from family members played a vital role in the physical and mental health of patients, making it easier to recover from the trauma of the disease. Therefore, the psychological discomfort and social barriers of patients require not only the joint efforts of doctors and patients, but also the care and support of their families.
Microsurgery technology, digital and 3D printing technology, and implantation technology enable vascularized iliac flap and fibular flap to reconstruct mandibular body defect to achieve a perfect functional repair effect. It not only shortens the operation time, restores the maxillofacial shape, but also achieves functional reconstruction and improves the patient’s QOL. it is recommended for patients with mandibular body defect to choose vascularized iliac bone flap for repair, while it is recommended for lesions with large defects or involving the condyle and chin to choose vascularized fibular flap to repair.