The zygomatic implant perforated (ZIP) flap: a new technique for combined surgical reconstruction and rapid fixed dental rehabilitation following low-level maxillectomy
© The Author(s). 2017
Received: 14 May 2017
Accepted: 23 July 2017
Published: 29 July 2017
This aim of this report is to describe the development and evolution of a new surgical technique for the immediate surgical reconstruction and rapid post-operative prosthodontic rehabilitation with a fixed dental prosthesis following low-level maxillectomy for malignant disease.
The technique involves the use of a zygomatic oncology implant perforated micro-vascular soft tissue flap (ZIP flap) for the primary management of maxillary malignancy with surgical closure of the resultant maxillary defect and the installation of osseointegrated support for a zygomatic implant-supported maxillary fixed dental prosthesis.
The use of this technique facilitates extremely rapid oral and dental rehabilitation within a few weeks of resective surgery, providing rapid return to function and restoring appearance following low-level maxillary resection, even in cases where radiotherapy is required as an adjuvant treatment post-operatively. The ZIP flap technique has been adopted as a standard procedure in the unit for the management of low-level maxillary malignancy, and this report provides a detailed step-by-step approach to treatment and discusses modifications developed over the treatment of an initial cohort of patients.
KeywordsLow-level maxillectomy Zygomatic implants Zygomatic oncology implant Fixed dental prosthesis ZIP flap Micro-vascular reconstruction Radiotherapy Early implant loading Oral cancer rehabilitation
The surgical management and prosthodontic rehabilitation of the maxillectomy patient is complex with a variety of options available to the head and neck cancer team ranging from simple prosthodontic obturation  to reconstruction using pre-fabricated or digitally planned composite flaps  with or without the placement of osseointegrated implants . The primary aims of treatment include effective eradication of the primary tumour, closure of the resulting maxillary defect, preservation of facial form, and ideally, the restoration of the resected maxillary dentition. Whilst the techniques for surgical closure of the low-level maxillectomy defect are well established, it can be challenging to subsequently achieve effective dental rehabilitation. The use of an obturator is not without its difficulties in terms of fit, retention and comfort, as well as preventing the transgress of fluid from the mouth to the nose. Providing and maintaining an effective obturator is demanding on both the patient and prosthodontist. Although some patients are able to tolerate the use of a removable denture following treatment, depending on retention, many are unable due to the change in the oral anatomy, oral dryness and the fragility of the irradiated tissues. Sealing the defect and providing bone and soft tissue through the use of free tissue transfer has both advantages and disadvantages. Following free tissue transfer providing secondary rehabilitation might be delayed or not possible. The situation is made worse by the frequent requirement for post-operative radiotherapy, which ideally should start as soon as feasible following tumour ablation.
The development of highly specialised tools such as zygomatic, oncology and co-axis implants (Southern Implants Ltd., South Africa) have provided a platform for effective maxillary dental rehabilitation in a rapid manner following maxillary resective surgery. Boyes-Varley et al. (2007)  successfully demonstrated the use of early loading in this cancer setting utilising oncology zygomatic and dental implants together with prosthetic obturation. Whilst implant survival was not a problem, the amount of prosthodontic maintenance was significant and most likely related to the complex issues around establishing and maintaining an oro-nasal seal in a changing maxillectomy cavity. The technique presented here incorporates an early loading zygomatic and oncology implant protocol for maxillectomy patients together with microvascular free-flap closure of the resultant defect with a fascio-cutaneous flap and early delivery of a fixed dental prosthesis within a few weeks following surgery.
The findings were discussed with the patient together with the treatment options for this malignant tumour requiring a low-level Brown class 2b maxillectomy . The patient preference was not to have prosthodontic obturation but rather reconstruction using microvascular free tissue transfer. In view of the unilateral low-level nature of the tumour, a soft tissue reconstruction combined with primary insertion of zygomatic implants to support a subsequent fixed dental prosthesis on a shortened dental arch concept was considered the best option. The remaining molar teeth were planned for extraction based on the potential need for post-operative radiotherapy and likelihood of trismus post-operatively. The remaining maxillary teeth on the non-defect right-hand side were planned for extraction to allow either the placement of immediate dental implants or the placement of conventional zygomatic implants depending on the state of the socket anatomy post-extraction.
Dental impressions were taken to allow construction of a maxillary complete denture template to both aid the placement of the zygomatic implants on the defect side and to act as an occlusal registration device during surgery. The occlusal vertical dimension was also measured between nasal tip and chin point to allow subsequent registration to occur at the correct level during surgery.
The ZIP flap technique
Patient-reported quality of life outcomes following ZIP flap procedure
100 (“I am as active as I have ever been”)
100 (“I am not anxious about my cancer”)
75 (“The change in my appearance is minor”)
100 (“I can chew as well as ever”)
75 (“I have a little fear, with occasional thoughts but they don’t really bother me”)
100 (“I have no problems with intimacy as a result of my cancer”)
100 (“My mood is excellent and unaffected by my cancer”)
100 (“I have no pain”)
100 (“There are no limitations to recreation at home or away from home”)
100 (“My saliva is of normal consistency”)
75 (“I have difficulty saying some words but I can be understood over the phone”)
100 (“I have no problem with my shoulder”)
100 (“I can swallow as well as ever”)
100 (“I can taste food normally”)
Most important aspect
Fear of recurrence
Procedural modifications to the ZIP flap technique
In order to reduce intra-operative time, the soft tissue free flap is harvested at the same time as the implant placement and prosthodontic procedures. On raising a skin island, it is appropriate to make it a little over-sized for the required defect to ensure that tension and possible dehiscence at the surgical margins during healing is reduced.
In low-level maxillectomy (Brown class II), the need for bony reconstruction is questionable depending on the horizontal component. With the preservation of the orbital floor, zygomatic prominence and some bony support for the nose, facial appearance, in the experience of the authors and, as demonstrated by this case, is not significantly worsened despite low-level removal of the maxilla. The key issues in these low level defects are adequate clearance of tumour, dealing with the oro-nasal communication and reconstruction of the dentition. Whilst prosthodontic obturation can deal with these aspects in a simple manner, the stability of the obturator prosthesis and its ability to completely seal the oro-nasal defect has limitations. In addition, these prostheses require a significant amount of adjustments, clinic visits and on-going maintenance. The soft lining materials perish, discolour and harbour surface biofilm often resulting in some mal-odour and the need for regular replacement. For many patients, there is a psychological impact of retaining the maxillectomy defect and high anxiety related to the insertion and removal of the prosthesis as well as concerns relating to the handicap they would experience to speech, and eating should their prosthesis fracture or fail in some way. The use of implants to retain maxillary obturators certainly improves their stability and retention, but efficacy of the oro-nasal seal still requires regular maintenance and patients still often dislike the hygiene aspects of looking after the defect and their implant supra-structure within the defect.
The use of soft tissue flaps to close a typical hemi-maxillectomy defect is an effective way of dealing with the oro-nasal communication, but in isolation, this technique works against dental rehabilitation as the bulk of the flap provides a very poor moveable foundation for a subsequent removable prosthesis. The move towards the use of composite reconstruction (especially the fibula flap) has been facilitated by the use of digital planning in which dental implants can be inserted into the fibula flap at the time of harvest and inset facilitated by the use of stereolithographic guides. However, this procedure is not widely applicable for all patients due to financial, technological and medical restrictions and is not currently able to provide patients with an early loaded fixed dental prosthesis especially when post-operative radiotherapy is being utilised. Many older patients presenting with maxillary malignant tumours also have significant peripheral vascular disease and other significant medical co-morbidities which may prevent the harvest of a vascularised composite flap.
In contrast, the use of a soft tissue flap such as the RFFF or antero-lateral thigh flap can often be safely employed in elderly patients with peripheral vascular disease without unduly lengthening the operation too significantly with two-team operating. In addition, the predictability of these flaps with their excellent pedicle lengths is ideal for closure of the resulting oro-nasal surgical defect. The use of a slightly oversized graft is recommended to ensure that any tension on the wound peripheries is kept to a minimum during the healing phase. In addition, for those patients undergoing post-operative radiotherapy, a degree of shrinkage and tightening of the flap tissues is to be expected.
Immediate/early loading of zygomatic  and dental implants  have been well demonstrated already within the literature with very high implant survival rates. In the oncology setting, Boyes-Varley et al.  lost no zygomatic/oncology implants in their series of 20 patients restored with implant-retained obturators, 6 of whom received radiotherapy post-operatively. The case reported has been followed up for 18 months so far without evidence of zygomatic implant failure despite the use of radiotherapy. A recent review of conventional zygomatic implant surgery demonstrated that the incidence of failure after the 6-month stage was extremely low  although for zygomatic oncology implants, this data is not yet fully reported in the literature with the only data available on zygomatic oncology implants being limited to the work of Boyes-Valey , Pellegrino  and the authors themselves . The removal of teeth at primary cancer surgery to facilitate placement of implants on the non-defect side requires careful consideration; where teeth are of poor prognosis with poor bone support, it is easier to extract, perform localised osteoplasty prior to the insertion of a conventional zygomatic implant with its inherent excellent stability and ability to be loaded early in the post-operative period. Where teeth have excellent bone support but additional implants are required to facilitate the construction of a fixed prosthesis, then careful extraction of selected teeth with the immediate installation of a root form implant can be utilised with good success as long as high primary stability is achieved at these sites.
Whilst technically, it would be possible to construct and fit the prosthesis on the same day or even a week later, the need for microvascular flap monitoring in the immediate post-operative period, together with the significant recovery period required by the patient following surgery has lead the authors to delay the fitting of the prosthesis at the 4 to 6-week period post-operatively. In terms of ongoing clinical implant follow-up, no attempt was made at peri-implant probing for the oncology zygomatic implants perforating the soft-tissue flap as it was deemed important not to disturb the soft tissue seal of the skin flap around the implant abutments. No discharge or suppuration was noted during follow-up in this case. Periodontal probing around the conventionally placed zygomatic implants was undertaken periodically during follow up and remained within normal limits.
The use of a soft tissue rather than composite reconstruction may also facilitate a shorter hospital stay and allow adjuvant radiotherapy to be delivered in a more rapid timescale with possible impact on overall cure rates of this very debilitating tumour. The initial experiences with this procedure in over ten cases have been extremely positive with excellent appreciation by patients who value being provided with a fixed dental prosthesis so quickly after major surgery.
The ZIP flap technique represents an innovative approach to the management of patients presenting with low-level malignant maxillary tumours. It provides effective closure of the resulting maxillary defect restoring speech and swallowing functions and also establishing a high-quality fixed dental rehabilitation in a rapid timescale, thus facilitating a more timely return to function and restored facial appearance. This approach has now been adopted routinely in the unit and it is hoped that a cases series will be presented in due course with more detailed patient outcomes. Further work on the long-term results of the ZIP flap procedure is required together with an ongoing appreciation of the important case selection factors for this treatment protocol.
CB devised the treatment concept and undertook all implant surgeries and prosthodontics. SR undertook all surgical resections and free flap reconstructions. CB and SR both wrote the manuscript and reviewed the available literature. Both authors read and approved the final manuscript.
Consent for publication
Consent has been obtained from the patient for the use and publication of all images.
Chris Butterworth and Simon Rogers declare that they have no competing interests.
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