Figure 1. Patient with surgical stent at stage II implant surgery. A, Three-dimensional reformation of a class II palatomaxillary defect reconstructed with a microvascular fibula free flap. Computer-assisted planning is for a fixed dental prosthesis (FDP) with 3 implants. B, The patient had implant placement shortly after free flap reconstruction prior to 6 weeks of radiotherapy. C, Once radiation treatment and osseointegration time (3 months) is completed, a stage II implant surgery with vestibuloplasty is performed using a surgical stent. D, A surgical stent in place with the replacement of teeth acts as a device for healing over 6 weeks and as a provisional FDP until definitive prosthetic restoration is fabricated.
Figure 2. Patient with immediate-load provisional restoration. A, Three-dimensional reformation of fibula free flap reconstruction of a left symphysis-body mandibular defect after segmental resection of an ameloblastoma tumor. Radiographic scanning appliance is in place to help determine position and angulation of implants. B, Computer-aided design and computer-aided manufacturing computed tomography–derived surgical guide in place at stage I surgery. Cylinders in the guide correspond to osteotomy sites for implant placement. C, Implants placed into osteotomy sites of the fibula. Bicortical stabilization is critical for success. Visualization of these sites was important to verify position. D, The implants were “early” loaded (2 weeks after surgery) by receiving a provisional fixed dental prosthesis in hypo-occlusion. Orthodontic treatment was indicated to correct the supereruption of the left maxillary teeth.
Figure 3. Treatment algorithm for computer-assisted implant rehabilitation and vascularized bone free flaps (VBFF) reconstruction. CT indicates computed tomographic; FDP, fixed dental prosthesis; and Ncm, Newton centimeters.
Figure 4. Patient with cantilever framework (design 2). A, Three-dimensional reformation of a right mandible reconstructed with a fibula free flap. The treatment plan includes 5 implants. Mucosal supported radiographic scanning appliance is in place. B, The height discrepancy of the fibula relative to the native mandible and the facial position of bone availability for implant placement relative to the dental arch are addressed with a cantilever framework design 2, fixed (cantilever). C, Symmetrical facial contour of the lower third of the face is first priority to restore outline form and cosmesis. D, The tissue of the neovestibule heals well around the gold alloy framework. E, Panoramic radiographic view of the implant-supported fixed dental prosthesis and fibula free flap reconstruction.
Figure 5. Patient with mesostructure-superstructure framework (design 3). A, Three-dimensional reformation of a reconstructed mandible with bone-supported computer-aided design and computer-aided manufacturing surgical template in place. The guide is subsequently fabricated via stereolithography prior to implant surgery. B and C, The severe height discrepancy of the native mandible relative to the fibula reconstruction is accounted for with a cast mesostructure. D, The fixed dental prosthesis (FDP) comprises a milled mesostructure with a corresponding superstructure that is retrievable and retained with setscrews (framework design 3, fixed; mesostructure-superstructure). E, Panoramic radiographic view of an implanted FDP and fibula reconstruction of the left mandible.
Figure 6. Patient with conventional framework (design 1). A, Computer-assisted planning of 6 implants into fibula free flap reconstruction of a class III palatomaxillary defect. B, A secondary split-thickness skin graft of the palate extending to vestibule was accomplished with a modification to the immediately fixed provisional restoration in an effort to improve hyperplastic tissue response around the implants. Palatal view of definitive screw-retained implant (fixed dental prosthesis) into a fibula free flap reconstruction is shown. C and D, Computer planning assists with the implant position so that screw access is not on the facial side (framework design 1, fixed [conventional]). Functional and aesthetic occlusal rehabilitation is restored with bilateral contacts and anterior guidance in mandibular excursive movements. E, A panoramic radiographic view of implant placement avoiding the plating system, conventional metal framework, and fibula free flap reconstruction. Note that there was 1 implant failure that had no change on treatment plan, prosthodontic design, and outcome.
Okay DJ, Buchbinder D, Urken M, Jacobson A, Lazarus C, Persky M. Computer-Assisted Implant Rehabilitation of Maxillomandibular Defects Reconstructed With Vascularized Bone Free Flaps. JAMA Otolaryngol Head Neck Surg. 2013;139(4):371-381. doi:10.1001/jamaoto.2013.83
Author Affiliations: Divisions of Prosthodontics (Dr Okay) and Oral and Maxillofacial Surgery (Drs Okay and Buchbinder), Department of Otolaryngology–Head and Neck Surgery (Drs Okay, Buchbinder, Urken, Jacobson, Lazarus, and Persky), and Institute for Head and Neck and Thyroid Diseases (Drs Okay, Buchbinder, Urken, Jacobson, Lazarus, and Persky), Beth Israel Medical Center, Albert Einstein College of Medicine, New York, New York.
Importance Functional recovery for patients who undergo maxillomandibular reconstruction with vascularized bone free flaps (VBFFs) is potentially more attainable with computer-assisted implant rehabilitation. This prosthodontic-driven approach uses software planning and surgical templates for implant placement supporting fixed dental prostheses (FDP). Implant success with immediate load (IL) provisional and definitive FDP restorations in VBFFs is reported for the first time in a patient cohort.
Objectives To determine implant success for FDP restorations and IL restorations. To determine factors that may influence success and predictability to provide FDP restorations in VBFFs.
Design A retrospective medical chart review was conducted of patients who underwent VBFF reconstruction and computer-assisted planning (CP) for FDP implant rehabilitation. This study was conducted with approval from the institutional review board at Beth Israel Medical Center, New York, New York.
Setting Clinical procedures were conducted in operating room and outpatient facilities in a tertiary referral medical center.
Participants Twenty-eight consecutive patient treatments were reviewed. Inclusion criteria for all patients were VBFF reconstruction and CP for FDP restoration prior to stage 1 implant surgery. Patients were evaluated for implant success, surgical templates, IL provisional restorations, and prosthodontic framework design. A comparison is made between patients with IL provisional restorations and those patients who did not receive an immediate restoration.
Main Outcomes and Measures Implants that achieved osseointegration and used for prosthetic reconstruction determined success. Prosthodontic design considerations included whether the patient received an IL provisional restoration and 3 categories of FDP metal framework design.
Results Ninety-nine implants of 116 implants placed were used for prosthetic restorations, achieving an 85.4% success rate. Twenty-five of 28 patients received FDP restorations. Thirteen of 28 patients received IL provisional restorations at stage 1 implant surgery. Fifty of 56 implants were successful (89.3%) in the IL group.
Conclusions Computer-assisted implant rehabilitation of reconstructed defects can achieve superior results to provide FDP and IL provisional restorations. This prosthodontic-driven approach also uses unique framework design to account for mandible height discrepancy after fibula free flap reconstruction. Patient management for FDP rehabilitation is also dependent on radiation status, soft-tissue modification, and patient selection.
A primary objective of surgical reconstruction and implant rehabilitation is to restore and advance masticatory, speech, and swallowing functions. Aesthetic considerations are equally important after tumor ablation when loss of structures that lend support to facial projection and symmetry are involved with the surgery. The goals of reconstruction may vary for different patients owing to a balance among the components of the defect, comorbidities involved with surgical reconstruction, and patient motivation. Contemporary treatment of the patient with head and neck cancer integrates surgical reconstructive techniques with prosthetic rehabilitation to optimize function and aesthetics.1- 3 Microvascular free tissue transfer for surgical reconstruction has been revolutionary in addressing the functional deficits from ablative surgery of large tumors. If bone is to be part of the reconstructive effort, then a method of fixation to ensure flap stability is determined until a bony union occurs. Major advancements of surgical reconstructive techniques and new approaches to the restoration of maxillomandibular defects effectively provide a more “conventional” setting for prosthetic reconstruction of the dentoalveolar arch and its interaction with surrounding structures. Composite free flaps from the fibula, iliac crest, and scapula regions are designed and harvested to address tissue volumetric loss to restore mandibular continuity, separate oral from sinonasal cavities, and provide a platform for fixture placement.4- 7 Vascularized bone free flaps (VBFFs) from the fibula or iliac crest donor sites provide good to excellent bone volume and the quality required by underlying bone for the application of osseointegration to prosthetic devices.8 The VBFF will either restore discontinuity of the mandible or reproduce the stable base of the maxilla.
Surgical reconstruction of palatomaxillary defects has evolved over the past decade to emerge as a viable option for patients undergoing resection of large tumors. While surgical closure of large palatomaxillary defects can provide closure of the oral cavity, problems are encountered with large, soft-tissue flaps, occupying the functional space over the tongue, that are not amenable for dental reconstruction. The use of VBFFs to reconstruct large palatomaxillary defects provides surgical closure and restores the stable base of the hard palate above the alveolar process.9,10 This approach optimizes function and addresses the shortcomings of an obturator for large maxillary defects.11,12 The VBFF permits the primary reconstruction of the orbital rim and the prominence of the zygomatic body with autologous tissue.
Vascularized bone offers the ability to reestablish the bony dental arch for the placement of osseointegrated implants. This allows for the distribution of masticatory forces across an intact maxillary arch and buttress system and thereby reestablishes a favorable biomechanical condition to the maxilla. Surgical reconstruction with fibula or iliac crest free flaps and implant rehabilitation with fixed dental prostheses (FDPs) replace analogous structures of a stable palatomaxillary complex.
Harvested bone from a distant donor site with its own blood supply presents additional strategies for osseointegration and prosthetic rehabilitation while reconstructing acquired defects from benign and malignant tumors. Among these strategies is taking advantage of the vascular bed for osseointegration prior to radiation therapy. The placement of implants in the immediate surgical setting will shorten the overall treatment time needed for a definitive prosthetic restoration. Once the bone is fixated to the reconstruction plate and the anastomosis of recipient vessels is completed, implant placement is performed. Following primary implant placement, the restorative team must allow 12 to 16 weeks for osseointegration and undisturbed healing.13,14 Once the patient completes radiation therapy after reconstruction and primary implant placement, the fixtures are uncovered after the soft-tissue reaction has subsided. At that time, soft-tissue modification, such as flap debulking or vestibuloplasty procedures, can also be performed. A surgical stent can be used and screwed into the implants for healing purposes prior to definitive prosthetic rehabilitation. Primary implant placement is helpful in developing a comprehensive approach to ablative surgery, subsequent reconstruction, and prosthodontic rehabilitation when adjunctive radiation therapy is contemplated. This strategy circumvents the need for preoperative hyperbaric oxygen treatment15,16 (Figure 1).
Advanced care for the rehabilitation of patients with head and neck cancer involves the application of computer planning software with computer-aided design and computer-aided manufacturing (CAD-CAM) of drilling guides that will allow the transfer of the virtual plan to the operating room. Computed tomography (CT)-derived implant surgical drill guides can be designed to be tooth, mucosa, or bone supported. This approach has ushered in a new way of thinking about implant-assisted prosthetic reconstruction. Rapid prototyping is an automated process with construction accomplished with a 3-dimensional printing, stereolithography machines with laser-driven polymerization, or sintering devices. Advanced digital technology can create accurate models from 3-dimensional imaging data or can be applied to the fabrication of surgical templates with the aid of software programs. The software programs allow for the virtual surgery in preoperative planning, and then these data are translated to the actual surgery via the drill guides. For implant placement, this approach is prosthodontically driven. A CT study is made with a radiographic scanning appliance. The appliance is fabricated with a mixture of polymethylmethacrylate and barium sulfate so that the position of the dentition and their surfaces are captured in the CT scan. The scanning appliance is fabricated from the duplication of a diagnostic wax-up or interim prosthesis17 (Figure 2).
The decision to use FDPs vs removable dental prostheses (RDPs) is dependent on clinical factors, such as bone availability, the number and position of implants, the need to assist or support restorations, hygiene maintenance, and manual dexterity. Aside from these clinical factors, other considerations, such as comfort and psychosocial implications, affect prosthetic design. Fixed dental prosthetic restorations are associated with superior chewing performance and aesthetics while causing less physiologic discomfort and psychological disability than their removable counterparts. Fixed dental prosthetic restorations are screw retained, and the prosthesis is retrievable. This design consideration is an important factor in cases in which direct visualization of tissue is necessary. There are also issues of maintenance. Composite free flaps can use muscle for lining the oral cavity, and, on occasion, peri-implant mucosa requires surgical debridement of hyperplastic inflammatory tissue. In addition, owing to a lack of innervation to the free flap, muscle will atrophy over time, requiring secondary impressions and reline procedures to prevent food debris from collecting under the prosthesis.
When planning the reconstruction of the complete dental arch with an osseointegrated FDP, a minimum of 5 or 6 implants with the greatest anterior-posterior spread is recommended to minimize the cantilever forces of the posterior extension of the prosthesis. Three to 4 implants are recommended for unilateral maxillomandibular defects. As the defect crosses the midline, more implants are necessary to support the replaced dental arch.
There is a 3-dimensional challenge in managing the height of the fibula as it relates to the dental arch and the native mandible. Despite this shortcoming, the advantages of the fibula free flap have made this a “work horse” flap for oromandibular reconstruction of discontinuity defects. The length of the bone harvest is excellent for reconstruction of the inferior border of the mandible in order to reestablish symmetry in the lower third of the face. The low donor site morbidity and its physical distance for a second surgical team associated with the fibula free flap harvest also contribute to its favorable characteristics. In addition, there is good to excellent bone stock for osseointegration. The bicortical nature of the fibula possesses approximately 12 to 15 mm of bone height for endosteal implant placement.18
A retrospective medical chart review was conducted of 28 patients who underwent VBFF reconstruction and computer-assisted planning for their implant rehabilitation. This study was conducted with approval by the institutional review board at Beth Israel Medical Center, New York, New York.
The treatment plan for all patients was FDP implant restorations after obtaining a CT examination on dedicated computer software (Materialise-Dentsply International; Nobel Clinician–Nobel BioCare) for implant surgery after microvascular free flap reconstruction. We have considerable experience with these software platforms since their introduction to the market. Patients were assessed for age, disease, defect classification, donor site, and radiation status. Implant data included implants planned with computer software assistance, implants placed during stage I surgery, and implants used for prosthodontic rehabilitation. Patients were also evaluated for CT-derived surgical templates, immediate provisional restorations, and prosthodontic framework design.
Mandibular defects were defined using the classification described by Urken et al.19 Defects were assigned letters c, r, b, or s to indicate defects of the condyle, ramus, body, and symphyseal regions, respectively. The symphysis was divided into right and left regions, and abbreviations in Table 1 are listed twice for bilateral defects, or rather, defects crossing the midline. The patient's maxillary defects were staged according to the classification scheme previously reported.11 This classification scheme allowed either class II or class III maxillary defects to be available for study. A treatment algorithm was developed to better organize our approach to rehabilitation incorporating soft-tissue modification and immediate restoration as additional factors to patient management (Figure 3).
If soft tissue overlying the bony reconstruction was thin and manageable enough for a transmucosal approach to implant surgery or if minimal soft-tissue modification was needed, the immediate restoration was fabricated prior to CT examination. Patients with minor soft-tissue modification at the time of stage I surgery were also considered for immediate restoration. The following techniques were implemented for patients requiring immediate loading of the implants. The desired contours of the restoration are achieved for aesthetics and tooth replacement. The provisional restoration can be duplicated in a mixture of acrylic resin with barium sulfate for a radiographic scanning device that is worn during the CT examination. A CAD-CAM tooth-supported stereolithographic guide is stabilized by the remaining dentition after the dental cast is optically scanned and registered into the software program. Surgical templates can either be fixated into the jaw or can be removable to check the implant osteotomy sites. If the implant primary stability is able to resist a force of more than 20 Newton centimeters (Ncm), then the provisional restoration can be attached with screw-retained plastic cylinders.20- 25 The restoration is placed in hypo-occlusion if the patient is partially edentulous. If the patient has a reconstructed class III maxillary defect, occlusal contacting forces in mandibular lateral movement and protrusion are minimized. Patients are instructed to remain on a soft, nonchew diet for several weeks. After 12 weeks, the provisional restoration is removed, and a definitive fixed restoration is fabricated with a customized metal framework. All implants supporting the immediate restoration either had transmucosal healing abutments placed or were attached to the prosthesis with screw-retained plastic abutment cylinders for fixation.
Implants that achieved osseointegration and were used for prosthetic reconstruction determined implant success. Prosthodontic design considerations included whether the patient received an immediate fixed restoration (attachment of denture at the time of implant surgery), the design of the definitive restoration (FDP vs RDP, or none), and the design of the metal framework necessary for the definitive restoration. The FDP framework designs were categorized as 1, conventional (the screw is accessible through the occlusal or lingual surface of the prosthesis); 2, cantilever (the screw is accessible on the facial side of the prosthesis); or 3, mesostructure-superstructure (the framework is in 2 segments held together with set screws).
Data collection for 28 patients in this study is represented in Table 1. A total of 122 implants were virtually planned on a dedicated computer software program for implant surgery, and 116 (95.1%) were subsequently placed in 28 patients who had undergone reconstruction with VBFFs. A total of 102 implants (87.1%) achieved osseointegration. Ninety-nine implants (85.4%) achieved osseointegration and were used for prosthetic restorations. Thirteen of 28 patients received immediately or early fixed restorations at stage I implant surgery (Table 2).
We have found that implants can be placed into the neoridge created by the VBFF without raising the soft tissue off the bony reconstruction or stripping the periosteal blood supply. This potentially decreases postoperative surgical pain and inflammation and allows for immediate implant loading of the fixtures. At the time of stage I implant surgery, immediate or early loading of the implants with the attachment of a provisional fixed implant-supported restoration occurs prior to osseointegration. When osseointegration is completed, approximately 3 months after immediate loading, fabrication of a definitive implant restoration can then accomplished. When stage I implant surgery is performed with CT-derived surgical templates after reconstruction, this accelerated approach to rehabilitation permits a shorter treatment time for a fixed implant restoration. Patient selection, radiation status, and soft-tissue considerations are important determining factors in managing care. One partially edentulous patient with a symphysis and body mandibular defect underwent reconstruction with a fibula free flap after radiation treatment and hyperbaric oxygen therapy. This patient, of the 13 patients receiving immediate restorations, had experienced 3 implant failures that changed the treatment plan. She subsequently underwent restoration with an implant-assisted RPD. Another partially edentulous patient with a bilateral symphysis and body defect who had undergone reconstruction with a fibula free flap had 2 implant failures of 5 implants placed and subsequently had the 2 implants placed again with the CT-derived surgical template. This occurred 6 weeks after the failed implants were removed. This patient was able to wear the immediately fixed restoration until definitive prosthetic rehabilitation was completed. The last patient with implant failure in the immediate restoration group had a class III defect reconstructed with a fibula free flap and had experienced failure of 1 of 6 implants placed. No additional implant surgery was performed, and the patient went on to have definitive FDP restoration. Another patient with a class III defect had 2 implants placed with a surgical guide prior to definitive FDP restoration in addition to having 4 existing implants placed at the time of fibula free flap reconstruction to improve anterior-posterior support. These 4 implants placed were not counted in this study, and the other 2 “early” loaded (2 weeks after surgery) implants were counted. All 13 patients with immediate restorations had CT-derived surgical templates for their surgical implant procedures. The success rate for implants in the immediate restoration group was 89.3% (50 of 56 implants). In addition, no implants were lost to failure owing to their inability to be used for prosthetic restoration.
Fifteen patients who did not receive an immediate restoration had an implant success rate of 81.7% (49 of 60 implants). One patient had 5 of 6 implants fail to osseointegrate. He did not receive a dental prosthesis. Another patient, after fibula free flap reconstruction and operative radiotherapy, experienced 2 implant failures. She subsequently underwent restoration with an implant-assisted RPD. In 7 of these 15 patients, CT-derived surgical templates were used to guide implant placement. Of the 8 patients who had computer-assisted planning without CT-derived surgical templates, 4 patients had been diagnosed as having malignant tumors and received postoperative radiotherapy. The 4 patients who received postoperative radiotherapy after implant placement and surgical reconstruction had an implant success rate of 88.9% (16 of 18 implants).
Twenty-five of 28 patients received definitive FDP restoration. The predictability of providing these restorations was 89.3%. Fifteen patients received framework design 1, conventional FDPs. Six patients had framework design 2, cantilevered framework. Four patients had framework design 3, mesostructure-superstructure design. One patient received an FDP restoration fixed to custom abutments with a luting agent. Two patients underwent restoration with an implant-assisted RPD. One patient did not receive a prosthetic restoration.
The complexity of rehabilitation for patients with maxillomandibular defects reconstructed with VBFFs makes it necessary to devise treatment strategies that advance care toward patient expectations in terms of function and aesthetic, psychological, and social aspects. Edentulous patients who do not achieve oral rehabilitation after cancer surgery can exhibit considerable psychological morbidity in addition to their functional deficits.26 Computer-assisted planning has been helpful for implant placement after surgical reconstruction of defects resulting from large maxillomandibular tumors. It compliments a treatment algorithm for reconstruction of the defects with vascularized bone flaps. It is based on 2 initial factors: whether adjuvant radiation therapy is planned and soft-tissue considerations (need for debulking). The potential for immediate FDP is based on patient selection, favorable comorbidity factors, and the lack of soft-tissue redundancy (Figure 3). Computer-assisted planning provides a platform for prosthodontic treatment planning, virtual implant surgery, and an opportunity to translate the planning to stage I surgery with CAD-CAM stereolithographic drilling templates. In our clinical setting, its application is routinely considered for prosthetic restorations of VBFF surgical reconstruction.
The exception is when implant placement occurs at the time of free flap reconstruction prior to radiation treatment to take advantage of the vascular bed. For some patients, though, the position of the vascular pedicle may not be conducive to primary placement, such that delayed primary implant placement is more beneficial. The fibula is tubular and triangular in cross section, and the 3 surfaces have dedicated characteristics. One surface has cutaneous perforators arising from the peroneal artery and vein, another surface is where the vascular pedicle runs, and the facial third is for rigid fixation. Orientation of skin and muscle; disruption of the pedicle; and which leg is used as a donor site, owing to vascular anomaly or atherosclerosis, are factors that contribute to whether the base or apex of the triangle is oriented as the neoridge of the maxilla or mandible.27 These factors have an important implication for whether implants are placed in the immediate setting with surgical reconstruction. Secondary placement of implants with computer-assisted planning is a progressive approach to prosthetic reconstruction of the dental arch and occlusion. Computer-assisted planning and CT-derived surgical drilling templates have shown potential for decreasing overall treatment time and improving accuracy of implant sites for FDPs. Computer-assisted planning can be used 4 to 6 weeks after VBFF reconstruction and prior to the initiation of radiation therapy. Treatment planning involves more implants rather than a minimum number to support a fixed restoration. In the event of an implant failure, prosthetic success is still achievable with restoration of a shorter dental arch or an RDP overdenture without added time or surgery.
Soft-tissue modification includes flap debulking and vestibuloplasty procedures to form a neovestibule. These procedures are perhaps best accomplished at stage II implant surgery with a surgical stent. The surgical stent is fixed to the implants and can be made with or without dentition. It promotes healing, maintains vestibular height, and improves the function and appearance of the lips and cheek. During this healing period and the time needed for definitive restoration fabrication, the stent can serve as a fixed provisional restoration. Six patients in this study received surgical stents at stage II with dentition. Two of these 6 patients had received postoperative radiation therapy without disturbance of healing (Figure 1).
Soft-tissue modification or debulking procedures can also be performed at the time of implant placement as well. If this is the case, a bone-supported (CAD-CAM) surgical template is indicated. With computer-assisted planning, the additional procedure for hardware removal can be avoided, with the number of implants and their sites clearly defined prior to surgery. Use of reconstruction plate fixation screws can be avoided with virtual implant planning surgery. Conversely, a decision can also be made to remove internal fixation hardware that may interfere with the placement of sufficient number of implants for a fixed restoration (as in 1 patient in this study who had a class III defect). Implant surgery is performed once bony union of the VBFF osteotomies is established, approximately 6 weeks after surgical reconstruction.28
The use of CT-derived surgical templates, while helpful, does possess shortcomings. The design of the guides can either be fixated to the jaw or removable. If the guide is fixed, then examination of the osteotomy is not possible until its completion prior to implant placement. Checking the preparation sequence of the osteotomy may be useful with a removable surgical template. In this study, there were situations in which the guide was used to locate the osteotomies to begin their preparation but were completed without the guide for full visualization. Bicortical stabilization is critical to success for implant placement in the fibula. Direct visualization of the implant is sometimes necessary for verification and should remain an option during surgery.
Perhaps one of our most impressive findings was for patients receiving immediate restoration. The success rate for implants in the immediate restoration group was 89.3% (50 of 56 implants). All 13 patients with immediate restorations had CT-derived surgical templates for their implant surgical procedures. Computer-assisted planning techniques can provide the desired position for tooth replacement with a radiographic scanning appliance worn by the patient at the time of cone beam CT examination. Implant position is determined by satisfactory bone volume, spacing, and implant angulation such that the abutment screw access is away from facial surfaces of the scanning appliance. The scanning appliance can be a duplication of the immediate restoration and can also have barium sulfate with polymethylmethacrylate in its composition. Ideally, implant surgery should be performed with a transmucosal approach or with an incision to visualize the osteotomy sites. Implant position favors abutment screw access either on the occlusal or lingual surface for aesthetic, conventional, screw-retained FDPs. The immediate restoration is attached to implants with resistant torque values greater than 20 Ncm. While overall treatment time may be similar to that of patients without immediate restorations, we found a potential to provide patients with fixed provisional restorations during the period needed for osseointegration and definitive FDP fabrication. This treatment time can take approximately 6 months and does not interfere with osseointegration or prosthetic success compared with those patients who did not receive immediate restorations. Also, these patients had strict diet restrictions during the first several weeks after implant surgery but exhibited high satisfaction with their care and rehabilitation process. This study widely applies this approach to treating patients with VBFF reconstruction of their maxillomandibular defects.29,30
Patients completing surgical reconstruction and requiring postoperative radiotherapy had timing constraints that did not allow for fabrication of CT-derived surgical templates. The computer-assisted planning was integral to overall success because of virtual placement prior to surgery. In patients receiving an immediate implant load, all individuals had surgical templates for a transmucosal or a minimally invasive approach, in which the visualization of the bone volume is replaced with the accuracy of replicating virtual placement. A prosthesis can be fabricated prior to surgery with this in mind. Computer-assisted planning and derived surgical templates are “next-generation” tools to implement implant rehabilitation.
Incorporating an immediately loaded restoration at implant surgery is also dependent on patient selection, prosthodontic design consideration, and improvement in the implant position from computer-assisted planning. The approach also depends on the ability to consistently provide FDPs as a definitive restoration overall. Three-dimensional simulation software provides the panoramic, axial, and transsagittal planes to perform accurate virtual implant placement with selected diameter and length according to bone availability. The implants are positioned to take advantage of the best bone stock, to avoid vital structures, and to ensure safety. The angulation of the fixtures is such that their screw access is confined to the occlusal surface rather than perforating aesthetic facial surfaces, which is desirable for a screw-retained restoration. Prosthetic design considerations are part of the computer-assisted planning stage because the tooth position and occlusal table are visualized.
Use of the fibula vs the iliac crest can present a geometric challenge for prosthetic reconstruction. As mentioned, the fibula is best positioned to reproduce the contours of the outline form for the lower third of the face. This may lead to an intraoral height discrepancy with the native mandible. In addition, the dental arch lies on the lingual side above the reconstruction such that implants placed can be positioned on the facial side of the dental arch and the occlusal plane. There are surgical techniques to overcome this height discrepancy. One is to position the fibula higher and use the reconstruction plating system to reproduce the contours of the inferior border. Another is the “double barrel” technique, in which the fibula is folded to increase the height of the fibula free flap.31 We have found that that the height discrepancy can also be addressed through prosthodontic design. The use of a metal framework designed to sit on the lingual side of implants can overcome their facial position and height discrepancy. An implant-supported FDP can then be constructed such that lip and cheek support is achieved. With this cantilever framework (design 2), screw access sits facial to the dental arch in the neovestibule. The resistance of cantilever forces is possible owing to the bicortical nature of the fibula (Figure 4). These concepts can also be applied to a screw-retained fixed restoration in the partially dentate patient by using a cast mesostructure-superstructure framework (design 3) to negotiate the severe height discrepancy of the native mandible vs implants placed into the fibula free flap. The mesostructure is milled so that the implant support is centralized over the mandibular neoridge and the corresponding superstructure acts as a fixed partial denture set with screws into the mesostructure.32 The contours of the mandibular prosthesis can provide support to the lower lip to restore projection and symmetry to the mouth. The loss of motor function from the marginal mandibular branch of the facial nerve from ablative and reconstructive procedures can be ameliorated with this means of lip support (Figure 5).
With mandibular reconstruction, the angulation of the implant may be difficult owing to the orientation of the fibula to overcome the height discrepancy of the native mandible and the lingual position of the dental arch in relation to the inferior border of the mandible. However, resolving these factors is not solely reliant on computer-assisted planning. Unique prosthodontic design considerations are needed for implant rehabilitation. The use of a mesostructure-superstructure framework (design 3) is necessary at times to overcome the severe height discrepancy of the mandible reconstructed with a fibula free flap (4 patients). A cantilever framework (design 2) will overcome the facial position of the implant. Six patients underwent restoration with cantilever designs expressing the facial position of the fibula and its orientation related to the dental arch. Computer-assisted planning can improve the position and angulation of implants so that the conventional framework (design 1) is achievable when there is a more favorable relationship to the fibula. In this study, 15 patients underwent restoration with conventional FDP frameworks (design 1) reflecting a more ideal and accurate position of implant placement.
Our finding of 25 of 28 patients (89%) receiving an FDP has implications for the predictability of treatment outcome, unlike findings of previous studies. While other studies33- 35 examined implanted prosthetic devices in bone flap reconstruction and their benefit, this study examines the predictability of providing fixed restorations to these patients and the potential for immediate restorations. Of the 25 patients receiving fixed implanted restorations, only 1 patient underwent restoration with a nonretrievable or cemented FDP. This patient underwent reconstruction with an iliac crest–internal oblique free flap of a mandibular (body and symphyseal) defect after resection of an ameloblastoma tumor without VBFF height discrepancy. As mentioned, FDP restorations have better results for chewing performance and aesthetics while causing less physiologic discomfort and psychological disability than RDP counterparts.36The rigid construct for the replacement of the dental arch is a near-normal design and explains this result in conventional or intact patients. This advantage of a fixed implant restoration can truly apply to patients with sensory deficits of the reconstructed defect and their need to avoid additional psychological trauma. Not having to remove a prosthetic component to their maxilla or mandible improves function and helps the patient overcome the traumatic experience of their disease and surgery without the frequent reminder. An FDP allows the intact sensate mucosa to remain exposed, optimizes function in class II maxillary defects, and leaves the native mandibular dentition free of removable partial denture metal frameworks. The VBFF and FDP optimize functional rehabilitation. The restoration of bilateral balanced occlusal contacts is a critical step to a functional occlusion. Occlusal rehabilitation with normal guidance and protection schemes can be restored to that of a naturally dentate individual. Dental occlusion is a focal point to oral rehabilitation after VBFF reconstruction and implant placement (Figure 6). It is a factor that our reconstructive team considers for improved mastication, functional outcome, and quality of life.
The financial cost for implant rehabilitation is a challenge to those undergoing treatment. Maxillofacial prosthetic Current Procedural Terminology codes do provide a means for reimbursement. However, insurance carriers tend to follow the way of Medicare and to not provide reimbursement for the additional cost of implant procedures associated with both benign and malignant neoplasms. Our institute provides these necessary services at discounted fees for this highly beneficial care. Computer-assisted planning allows for predictable success and therefore, potentially, further cost benefit.
In conclusion, a treatment strategy is described for implant rehabilitation after free flap reconstruction of maxillomandibular defects. Computer-assisted implant rehabilitation of reconstructed defects can achieve superior results to provide FDPs and immediate restorations. This is a prosthodontic-driven approach that also uses unique framework design and mesostructures to account for mandibular height discrepancy after fibula free flap reconstruction. Patient management for FDP rehabilitation of the reconstructed defect is also dependent on radiation status, soft-tissue modification, and patient selection. This approach advances function and rehabilitation for these patients.
Correspondence: Devin J. Okay, DDS, Beth Israel Medical Center, Institute for Head and Neck and Thyroid Diseases, 10 Union Square E, Ste 5B, New York, NY 10003 (email@example.com).
Submitted for Publication: September 17, 2012; final revision received December 18, 2012; accepted January 3, 2013.
Author Contributions: All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Okay and Buchbinder. Acquisition of data: Okay and Buchbinder. Analysis and interpretation of data: Okay, Urken, Jacobson, Lazarus, and Persky. Drafting of the manuscript: Okay. Critical revision of the manuscript for important intellectual content: Buchbinder, Urken, Jacobson, Lazarus, and Persky. Administrative, technical, and material support: All authors.
Conflict of Interest Disclosures: None reported.
Previous Presentation: This study was presented at the American Head and Neck Society Eighth International Conference on Head and Neck Cancer; July 23, 2012; Toronto, Ontario, Canada.
This article was corrected for errors on July 10, 2013 and July 31, 2013.