Are Vascularized Bone Grafts Helpful in Lower Jaw Rehabilitation?
Free flaps, especially vascularized bone grafts (VBGs), are considered one of the primary reconstructive modalities for segmental or complex defects of the mandible. For the rehabilitation of adjacent soft tissues in the oral cavity, popular flap surgeries include the fibula-free flap, the scapular flap, and the iliac crest flap. These have been exceedingly successful in orofacial and head and neck reconstructive surgeries. Among these, the fibula flap is often the primary choice for mandibular reconstruction due to several benefits. The double-barreling technique of the fibula flap is one of the most potent surgical methods for achieving accurate and predictable post-surgical outcomes for the rehabilitation of complex lower jaw or mandibular defects.
Whether hard tissue or soft tissue grafting is required for lower jaw or mandible defects caused by head and neck cancers, secondary metastasis to the lower jaw, orofacial traumatic injuries from accidents, cancer resection surgery defects, or large recurring benign jaw tumors that may create functional issues, the free fibula vascularized bone graft can be one of the less complex and more beneficial surgeries for rehabilitating these defects.
Can Double-Barrel Technique of Free Fibula Graft Overcome Drawbacks Associated With Complex Lower Jaw Surgeries?
One of the minor drawbacks of surgery, however, is that the fibula flap graft cannot provide sufficient bone height to restore the actual or original height of the mandible in affected patients. A common surgical challenge faced by maxillofacial surgeons in this area is the vertical discrepancy that arises between the remnant mandible and the fibula flap placement. The drawback of reducing the vertical dimension in the lower third of the face, with potential aesthetic and functional sequelae, further complicates cases, making the free fibula flap difficult for implant placement or prosthetic rehabilitation of the lower jaw.
Postoperative consequences, such as implant overloading or a lack of functional stress-bearing capacity, can lead to the failure of dental implants or rehabilitation, creating both functional and aesthetic long-term discomfort. To overcome these discrepancies in free fibula flap surgery, surgical researchers have proposed the double-barreling method.
According to dental researchers, the double-barrel technique of the free fibula flap for the lower jaw primarily addresses hard and soft tissue mandible defects exceeding 3.94 inches. The surgical site must meet certain criteria, such as possessing adequate periosteal and medullary vascular supply along with a long, anatomically constant vascular pedicle for hard tissue rehabilitation or a large skin paddle for soft tissue reconstruction.
The feasibility of dental rehabilitation with a free fibula flap should always be preoperatively assessed by the maxillofacial surgeon or dental implant specialist, particularly concerning prosthetics such as implant-supported or implant-retained prostheses needed to rehabilitate patients with lower jaw defects.
In the double-barreling technique, the bicortical bone of the lower jaw is ideal for achieving a foundation or primary stability for dental implants, while the donor area's morbidity is significantly lower compared to other flap approaches in maxillofacial surgery.
Computer-aided design and computer-aided manufacturing (CAD or CAM) technology can also play a critical role in planning and executing such procedures. CAD or CAM enables precise reconstruction of the mandible, ensuring optimal alignment, aesthetics, and function postoperatively.
What Are the Surgical Steps in Double Barrel Technique?
The main steps in the double-barreling method of the free fibula flap involve several surgical modifications that the oral or maxillofacial surgeon can adopt. However, the first step is always an imperative and thorough preoperative assessment performed with the help of virtual surgical planning (VSP) methods.
In this technique, the surgeon creates a double-barrel flap at the recipient site in an affected patient using the free fibula graft. This requires a double-barrel customized titanium plate, followed by immediate implant placement. In many cases, the surgeon subsequently uses a computer-aided design and computer-aided manufacturing (CAD or CAM) titanium mesh filled with an iliac crest onlay graft over the fibula flap as a second-stage procedure.
Additionally, vertical distraction osteogenesis of the fibula flap can be performed. This step is essential in addressing significant vertical discrepancies and optimizing bone height for successful rehabilitation.
To ensure the success of graft surgery, it is crucial to complete mandibular reconstruction comprehensively, guaranteeing the aesthetic and functional oral rehabilitation of patients with mandible defects. At this stage, the placement of dental implants becomes integral and must be performed optimally to achieve long-term success.
Intraoperative navigation plays an important role in the double-barreling method. It allows for highly accurate and predictable post-surgical outcomes, particularly in patients with severe or high-grade bony or soft tissue defects. Intraoperative navigation is also essential in cases with altered or complex lower jaw anatomy, ensuring precise alignment and improved reconstruction outcomes.
Importance of CAD or CAM and Intraoperative Navigation in Double Barrel Technique:
CAD or CAM design, modeling, and intraoperative navigation techniques have been hailed as revolutionary advancements in modern maxillofacial surgery over the last decade. These methods simplify the surgical process, reduce operator and patient chair time, and improve the accuracy of surgeries. Through thorough preoperative understanding and planning by the maxillofacial surgeon, preplanning is carried out for the exact locations of osteotomies (surgical procedures that involve cutting and reshaping bones to correct deformities or improve alignment) for bone flap surgeries. These technologies are particularly useful for a range of defects, including those caused by cancer, burns, or accidents, which result in hard and soft tissue deficiencies in the lower jaw.
CAD or CAM guides and intraoperative navigation systems hold great potential in guaranteeing optimal postoperative results with minimal scope for iatrogenic or operator-based errors.
Conclusion
Current dental research underscores the outcomes from free vascularized bone grafts (VBGs), such as the free fibula grafts, as significantly superior and positively impactful for long-term success in rehabilitation surgeries of the lower jaw. In mandibular reconstruction surgeries, the modifications in surgical techniques, such as the double-barreling technique, hold promising potential for maxillofacial surgeons. These techniques allow surgeons to achieve both aesthetic and functional rehabilitation of the mandible without compromising the long-term comfort of patients.
