The use of dental implants and prostheses in the oral rehabilitation process after maxillofacial ablation procedures is now regarded as standard practice. Numerous donor sites for free vascularized bone transfer in head and neck reconstruction have been well-documented in the literature including the ribs, ilium, fibula, scapula, and radius. Among these, the fibula is the most commonly used and studied for placing endosseous implants and for rehabilitation purposes. There are benefits and drawbacks to the fibula flap. This paper aims to provide a review of the current research on the long-term success rates of implants in fibula free flaps.
Key points
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The efficacy and prognosis of dental implants placed in free bone flaps have been extensively studied, with the fibula free flap being an ideal option for mandibular reconstruction with dental rehabilitation.
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Patients reconstructed with free fibula flap (FFF) and implant-supported overdentures showed statistically significant improvements in quality of life (QOL) when compared with no prosthesis or non-implant-supported prosthesis in post ablative defects.
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Dental implants can be placed in free fibula flaps using immediate, secondary, or jaw in a day technique. These techniques should be individualized based on the patient’s diagnosis, history, prognosis, motivation, needs and wishes.
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Success rates of dental implants placed in nonirradiated fibulas are comparable with those placed in native bone.
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Implants inserted into the irradiated maxilla have a lower survival rate than implants inserted into the irradiated mandible and irradiated FFF implants have a lower survival rate than native maxilla or mandible implants.
Introduction
When bone integrity is compromised due to trauma, infection, large jaw cysts, or ablative oral cancer surgery, jaw reconstruction is frequently required. Reconstruction of the maxilla or mandible using a fibula free flap is the recognized standard of care when surgical resection involves segmental resection. An increasingly popular treatment strategy for patients with head and neck cancer is the use of dental endosseous implants and overdentures as part of their oral and dental rehabilitation. There are several advantages to implant anchorage compared to traditionally secured prostheses, but most importantly is the significant improvement in the reported quality of life of patients. The first reports of dental prosthetic rehabilitation of the mandible using free tissue transfer and endosseous implants dates back to 1989. , The efficacy and prognosis of implants placed in FFF has been extensively studied. The ease of harvest, availability of long span of bone, segmental periosteal blood supply, length of vascular pedicle, pliability of skin paddle, reliable vascular anatomy, and ability to use a 2-team approach make the fibula free flap an ideal option for mandibular reconstruction with dental rehabilitation.
Success rates
Implants placed in native bone have similar success rates to those placed in non-irradiated fibulas. After one to 5 years of placement, the average overall survival rate of implants placed in FFF is 93.5%, with a range of 83.3% to 97%. These implants have an average 10-year survival rate of 80% and a reported 20-year survival rate of 69%.
Kolokythas and colleagues conducted a meta-analysis with data obtained from 242 patients and a total of 848 dental implants placed in free fibula flaps secondarily. The estimated proportion of successful implants placed in fibula flaps used to reconstruct the maxillomandibular complex was 0.94 or 94% (95% CI [confidence interval] = 0.91–0.96]). The annual implant failure rate was 0.02 with a 95% CI = 0.01 to 0.03.
Liu and colleagues conducted a meta-analysis to compare the survival rate and complications between primary and secondary implantation specifically associated with vascularized fibula transplantation for reconstruction of jaw defects. 7 studies were involved with 186 patients. The survival rate of the primary implantation was 93.3%, The survival rate of the secondary implantation was 93.4%. The meta-analysis further proved that there was no significant difference in the survival rate between primary implantation and secondary implantation, OR = 0.813 (95% CI 0.383–1.725, P =.589 > 0.05)
Ch’ng et al investigated the rate of implant loss in patients with head and neck cancer who had implant placement in fibulas and native jaws before and after radiation treatment. They discovered that, while not statistically significant, there was a slightly higher rate of loss in fibulas (8.6%) than in native mandibles (2.6%) and maxillas (2.2%). Furthermore, there was no statistically significant variation in implant loss between patients who underwent adjuvant radiation therapy and those who did not. When comparing patients who had a fibula and primary implant placement to those who had not, Sandoval and colleagues specifically studied the effects of adjuvant radiation therapy in patients reconstructed with a fibula and primary implant placement compared with fibulas without implant placement and found no significant difference in adverse outcomes.
Radiation and pathology did not significantly affect implant survival statistically. Implants inserted into non-irradiated fibulas have success rates that are similar to those of implants inserted into native bone. After one to 5 years of placement, the average overall survival rate of implants placed in FFF is 93.5%, with a range of 83.3% to 97%. , These implants have an average 10-year survival rate of 80% (range: 78%–83%), and a reported 20-year survival rate of 69%. Maxillofacial subunit reconstruction using an implant-supported prosthesis and FFF has a high implant survival rate, minimal crestal bone loss (<1 mm), and minimal complication rates, making it durable over the long run. Implants placed in FFF exhibit a higher overall implant loss and peri-implant bone loss in comparison to native bone, especially when placed in the maxilla. ,
Virtual surgical planning
Virtual surgical planning is a major factor in both primary and secondary implant placement. It involves computer-aided surgical planning and the creation of surgical guides using computer-aided design and manufacturing (CAD/CAM) technology. Virtual surgical planning (VSP) enables accurate evaluation of anatomy, creation of a patient-specific plan for FFF and implant placement, and implementation of this plan using custom-fabricated cutting and implant placement guides. By using this technology, endosseous implant placement can be planned while avoiding the reconstruction plate and screws ( Fig. 1 ). The precise cutting of the fibula segments in patient-specific reconstruction plates, as well as the planning of osteotomies in the defect site, are made possible by prefabricated fibula cutting and implant placement guides made using VSP ( Fig. 2 ). Moreover, it permits the optimal positioning of endosseous implants in the fibula bone, with predefined angulation and position that facilitates prosthetic rehabilitation, and it prevents interference between the implant and the transosseous screws that secure the FFF.
This results in increased rates of tertiary rehabilitation and more efficient fabrication and placement of a final prosthesis. Reduced operating times, fewer procedures, increased utilization of implants, shorter prosthesis delivery times, higher rates of tertiary prosthetic rehabilitation, and enhanced patient satisfaction and quality of life make up for the higher cost of VSP. ( Fig. 3 )
Immediate, secondary, and jaw in a day
A number of factors make the post-ablative patient an unsuitable candidate for conventional (non-implant-supported) dentures: low bone density, poor soft tissue quantity and quality, complications related to radiation therapy, such as soft tissue loss and xerostomia leading to ulceration from acrylic rubbing against the mucosa, poor denture retention, and poor suction.
The placement of dental implants in free bone flaps can be done using 1 of 3 methods: “Jaw in a day,” primary, or one-stage, and secondary, or 2-stage. Primary or one-stage implant placement in FFF can be safely carried out without vascular compromise to the flap. It adds extra time to the total surgical period, and overall FFF warm ischemia time is less than 4 hours. This procedure improves functional outcome and is cost-effective because it decreases overall reconstruction time by reducing the number of OR visits. Immediate implant placement has several benefits, such as easier access to the fibula bone, fewer surgical procedures, reduced cost, early oral rehabilitation, and a quicker return to oral nutrition and prosthesis use. It also gives implants time to osseointegrate before beginning radiation therapy and may lower the risk of implant loss. Implant placement errors, radiation therapy interference, changes to the local anatomy, and the potential for tumor recurrence at the implant placement site that hinders surveillance are among the drawbacks of this technique. Primary implant placement following the excision of a malignant tumor is not advised due to the possibility of recurrence.
The placement of secondary implants is done in 2 steps. The bone defect is reconstructed in the first stage using a reconstruction plate and FFF, after which it is left to heal for 4 to 6 months. The optimal location and angulation for implant placement are determined in the second stage by the surgeon with the assistance of VSP technology. The secondary implant placement is postponed for a year following the conclusion of therapy in malignant tumor defects treated with FFF and adjuvant radiation therapy. In second-stage surgery, reconstructive hardware is removed if it gets in the way of implant placement. Vestibuloplasty, flap skin paddle debulking, and surrounding implant grafting can be completed concurrently with implant placement or during implant uncovering. ( Fig. 4 ) Secondary implant placement has several benefits, such as identifying patients who are motivated to pursue additional prosthetic rehabilitation, a shorter initial surgical procedure, developing an optimal implant placement guide and prosthodontic plan, and providing time to rule out local tumor recurrence. The drawbacks include higher costs, more OR visits, a longer time for oral rehabilitation.
With today’s virtual technology, the fibula free flap, guided implants as well as the dental prostheses can all be placed in a single surgical procedure ( Fig. 5 ). Despite the limited experience of Jaw in a Day with malignant disease, preliminary reports indicate that it can be successfully used for patients who require adjuvant radiation therapy following surgery. It is likely that radiation therapy has detrimental effects on bone that take several weeks to manifest. Since radiation usually starts 6 weeks after surgery, a large portion of the osseointegration process has already taken place before higher radiation doses are accumulated.
The primary implant placement strategy of placing implants in nonradiated bone has been supported by prior research. Implant placement prior to radiation therapy appears to have no effect on the rate of successful integration and may even slightly increase the survival rate.
The introduction of CAD-CAM and the high success rates linked to this method have spurred a trend toward rapid prosthesis fabrication and implantation, as several case studies and reports have shown. Chiapasco and Gatti were the first to demonstrate the immediate prosthetic loading of implants. In their study, 2 patients with severely atrophied, edentulous maxilla were treated with fibula free flap reconstruction followed by the placement of the prosthesis and implants 3 months later. Every implant was found to have survived its owner. Similarly, Okay and colleagues examined 28 patients and found that, 3 months after free flap reconstruction, patients who had immediate loading of a provisional prosthesis had an implant success rate of 89.3%. These findings opened the door for single-stage total maxillomandibular reconstruction by indicating that there was potential for immediate functional loading of implants ( Fig. 6 ).
Techniques
At the head, the fibula bone has a triangular shape; in the middle, it becomes more quadrilateral, and at the malleolus, it becomes oval or irregular. In most cases of reconstructed defects, the distal fibula bone—which is typically quadrilateral in shape—is used to enable a longer vascular pedicle length.
The ideal position for the fibula bone is one that avoids the screws from the reconstruction plate and permits the angulation of the implant placement. Ideally, segments of the osteotomized fibula should not be smaller than 2 cm. ,
Although fibulas positioned at the inferior border produce aesthetically pleasing results, the prosthesis must have a significantly taller structure due to the resulting lack of vertical “alveolar” height, this can result in higher loading forces on the implants. One of the ways to prevent this is by placing the fibula segment 5 to 10 mm above the mandibular inferior border. Another important consideration is the space needed to place the implants, take dental impressions, allow mastication, and deliver a prosthesis a minimum of 15 mm of mouth opening is needed at the incisal edge of the anterior teeth. There should be a 10 to 15 mm space between the superior edge of the fibula and the occlusal edge of the opposing dentition to enable the development of the implant-supported framework of the prosthesis. The placement of implants in native jaw bone follows the same guidelines as the placement of implants in fibula bone, with the exception of the high bone density fibula, where bone fracture after implant drilling must be avoided by tapping the implant osteotomy site.
Endosseous implant placement requires the fibula bone to be at least 10 mm in height and 5 mm wide. , Bicortical implant placement is crucial in FFF due to the absence of cancellous bone in order to achieve stability and higher removal torque values. It is recommended to plan for a maximum of 2 implants per 2-cm fibula segment. To preserve the maximum amount of bone vascularity, segments should be stabilized using a reconstruction plate and 1 or 2 screws.
In order to stabilize longer fibula segments, prevent micromovement at the osteotomy site, and minimize rotational forces on the segments, a minimum of 2 monocortical screws should be used. The recommended minimum spacing between 2 implants is 3 mm as in the native mandible. Additionally, the implant should be at least 0.5 mm from the cortical plate of the lingual or buccal fibula bone, and at least 3 mm from the osteotomy site.
For the purpose of prosthetic rehabilitation, implants ought to be oriented parallel to each other and with the proper angulation. Angled abutments allow for a maximum of 15° of divergence during prosthesis fabrication. Implant insertion torque should be set at a minimum of 20 Ncm and a maximum of 45 Ncm, respectively. A surgical guide using bone, mucosa, or tooth support can be used to direct the implantation of endosseous implants in the bone. Implants can be precisely positioned, angled, and spaced with a 1 mm margin of error when implant placement guides are used. A screw-retained prosthesis can be provided immediately if the implant insertion torque is 35 Ncm or higher. A 2-stage protocol is employed if the insertion torque is less than 35 Ncm.
In order to achieve a consistent outcome, accurate preoperative planning is essential. A computed tomography (CT) scan of the fibulas and jaws with 1 mm cute is first obtained. Using an intraoral optical scan, a digital file that can be used as a template for making a temporary dental prosthesis and as a reference for implant positioning can be created. The stereolithography digital format is the most widely used. When a patient’s preoperative dentition is intact, a temporary prosthesis can be made by 3D printing the teeth that were cloned using an optical scanner. ,
For the virtual planning session, the intraoral scan digital file must be uploaded to the VSP planner in order for it to match the CT data. Dental implant placement, fibula orientation, mandible resection location, and plate/screw design comprise the 4 components planned using VSP. Optimal fibula positioning should be the foundation for mandible osteotomies in addition to margins that are clinically sound. Sometimes it is necessary to extend the resection margins in order to avoid short fibula segments, which might have a less robust blood supply. ,
Type of implants and prosthesis
Implant survival is not influenced by the brand of the implant. The majority of implant systems that are sold commercially are equally suitable for FFF dental restoration. When compared to machined implants, implants with treated surfaces have comparatively fewer failures. This is probably because rough-surface implants have a larger surface area and accelerate osseointegration. When placed in irradiated fields, short implants have higher failure rates than standard-size implants (10 mm or longer). In light of these findings, FFF reconstruction should employ a surface-treated implant with a minimum width of 3 mm and a minimum length of 10 mm.
Bar connectors are preferable to ball-and-socket connectors because they minimize implant micromovements and resolve issues with misaligned or incorrectly positioned implants. A removable implant-supported prosthesis with ball-and-socket connectors has a higher failure rate.
Poor intermaxillary relationships, tumor recurrence, implant loss, microstomia, and a lack of patient cooperation are among the factors that contribute to the failure of prosthetic rehabilitation. A poor emergence profile, increased loading forces, and stress on the implants are caused by implants with poor vectors, misaligned arches, long abutments, and increased distances between the fibula and opposing occlusal surface. These factors may compromise the long-term survival of the implants. A minimum of 4 implants should be positioned per arch for edentulous patients receiving treatment with implant-supported overdentures. In 2016, Kumar and colleagues found no difference in the quality of life (QOL) between patients treated with overdentures based on 2 versus 4 implants, despite the fact that patients treated with the 2-implant system had higher marginal bone loss.
Ideally 4 implants with bar attachments are used to support the removable implant-supported overdenture. The prosthesis survival rate for patients who have undergone rehabilitation is high—more than 98%. Patients who have FFF and overdentures supported by implants fare better than those who do not. Patients reconstructed with FFF and implant-supported overdentures showed statistically significant improvements in QOL when compared with no prosthesis or non-implant-supported prosthesis in post ablative defects. For these patients, there are restorative options such as hybrid prosthesis, overdentures, and implant-supported cement or screw-retained bridges.
Implant-supported obturators can be utilized by maxillectomy patients to seal oronasal communications created by the defect.
In order to minimize the risk of pressure necrosis and soft tissue ulceration, the best option would be a fixed hybrid screw-retained prosthesis that does not rely on the mucosa. Cement-retained prostheses and acrylic restorations should be avoided as they cause granulation tissue formation around the implant and bone interface ( Fig. 7 ).
