The zygomatic bone was adequately exposed. Implants from Noris Medical Ltd. (Nesher, Israel) were chosen. The working, threaded part of the implant is 13 mm long, while the remaining, fully smooth shaft has 4-mm diameter and variable length. In all, length ranges from 35 to 57.5 mm. Implant drilling was performed using both straight and angled handpieces. The fixtures were placed at 35 rpm for the 2/3 of the apical and manually for the most coronal 1/3 working part. Palatal-alveolar repair was attained with soft tissue, local flaps: these were also wrapped around the implants. In order to obtain a durable watertight seal between oral and nasal/antral cavities, implant uncovering and loading were planned to be deferred by 3 months.
CT scans and/or panoramic radiograph were taken to monitor implant healing.
Screw-retained fixed prosthesis was considered for teeth replacement.
Discussion
Neoplasms of the maxilla often require extensive surgery and adjuvant treatments: as a consequence, quality of life might result as heavily impaired.
Reconstructive surgery (immediate or delayed) allows anatomic and basic functionality restoration following maxillary tumour resection. Actually, the most important goal has to be achieved—as earlier as possible— is the repair of the natural barrier between oral and nasal/antral cavities: options include free or local flaps and obturator.
Free flaps may either be harvested as single component, or as soft tissue and bone complex. Among the latter, fibula, iliac crest, and scapula are the most popular, with personal preference for the fibula flap. These composite auto-transplants allow both restoration of the oronasal/antral barrier and bone support for implants. Disease-related indications for composite free flaps include repair of large defects (2/3 of the palato-alveolar complex) and 3-D maxillary reconstruction. Their use implies large consumption of resources, yet patients’ survival is quite rewarding [
13].
In contrast, local and regional flaps are less demanding, but their use is restricted to more limited palato-alveolar defects (up to the midline). The temporalis muscle is the workhorse for repairing such defects, while buccal fat pad has room in case of minor oronasal/antral communications [
14]. When needed, adequate bone support may be set by secondary bone grafting.
Finally, prosthetic obturator is recommended when the above solutions cannot be available or are contraindicated: it requires adequate anchoring (residual dentition, standard implants, deep vestibular sulcus) and continuous servicing.
In our opinion, primary closure by flaps should be preferred over prosthetic obturator, as this approach makes the patients more comfortable and prosthesis-free, immediately and during his/her daily activity. Indeed, in all three patients, local flaps have performed well and led to successful immediate closure of the oroantral communication following tumour ablation. Seok et al. [
14] advocate the application of 4-hexylresorcinol in order to accelerate and improve re-epithelialization.
Common belief stresses that follow-up in patients wearing obturator would be easier and safer than that in patients having surgical closure of the palate. In fact, possible local recurrence of the tumour could be detected early, yet benefit in survival of such a policy has not definitively proved. Moreover, modern imaging techniques could be at least as effective as inspection in revealing possible relapse at an early stage.
Nevertheless, some patients are or become more demanding about full or maximum recovery of the finest activities linked to chewing, phonation, deglutition, and aesthetics: in these cases, dental rehabilitation through implant-supported prosthesis might greatly help, the fixture(s) being usually inserted in native or grafted bone. Zygomatic implants could overcome the possible problem of lacking or poor-quality bone [
2,
5,
12,
15‐
22]. In such patients, ZI is usually a delayed, multi-staged procedure, either after having primarily closed the oronasal/antral communication [
12,
17,
19], either after left it untreated or amended with obturator [
5,
16,
18]: the overall time from tumour treatment and final dental rehabilitation might require 1 year or more. Intuitively, interest has arisen in shortening this gap and we planned to move toward this direction.
The relatively innovative aspect of the present paper deals with the idea of challenging three different tasks in a single-stage procedure: resection of the tumour, closure of the oronasal/antral communication, and insertion of the zygomatic implants finalized to a fixed restoration. In few words, we tried to reach the best cost/benefit ratio.
Indeed, Pellegrino et al. [
12] should be credited for the first reported case, even if not clearly evident from their paper (personal communication from Prof. C. Marchetti). The authors also proposed a new classification of rehabilitation-orientated maxillary defects: in our opinion, it deserves attention because of its clarity and effectiveness in orientating therapeutic options.
We were able to complete the above plan within the expected period of 3 months in patient no. 1, whose outcome is optimal after 1 year.
Supplementary advantage of ZI at the time of tumour resection is to give implants sufficient time to become osseointegrated before prospective radiotherapy course, then avoiding or minimizing its well-known negative impact on healing [
23]. Actually, patient nos. 2 and 3 took some benefits from this policy.
In addition, applying a maxillary prosthesis in the early stages minimizes contraction of facial soft tissues [
16].
We performed ZI under direct vision, enhanced by resin guide pointing landmarks. The procedure was somewhat easier than ZI in simply atrophic patients, as the resected bone allowed more room to vision and manipulation. On the other hand, the prepared flaps and the residual dentition could make things a bit more difficult than usual situations. Some authors advocate either general [
24] or specific computer-aided surgery [
12,
25], or surgical navigation [
15,
26], for accurate, safe zygomatic implant installation. Undoubtedly, these are effective apparatuses, whose limitations are availability and operating costs. The pilot hole technique [
27] and piezosurgery could offer similar advantages—at least in terms of safety—with lower costs.
Zygomatic implants are most suitable for immediate loading in reason of the high torque usually necessary for their insertion and consequent outstanding primary stability. However, we privileged the delayed loading to achieve and maintain an adequate seal between oral and nasal/antral cavities.
Long-term results of ZI are quite satisfactory. Brånemark [
2] reported a 97% success rate in a series of 184 zygomatic implants inserted in 81 patients. Aparicio et al. [
10] conducted a large review of zygomatic implant survival: success rates ranged 94.4 to 100%. Recently, Chrcanovic et al. [
11] extended the analysis over 4556 zygomatic implants in 2161 patients: they found a noteworthy 12-year cumulative survival rate of 95.21%.
Despite the prosthetic aspects of the proposed technique are somewhat beyond the paper scope, some considerations appear obliged. Screw-retained, metal-core dental prostheses are popular, manageable devices allowing easy removal for fixture inspection and cleaning. An interesting point is that in patient no. 1, the interdental and inter-arch obligations lead to a double-cantilevered dental restoration, entailing a possible overload: to mitigate it prudently, mesial (to 23) and distal (to 27) splinting were conceived. Indeed, implant stability was preserved, as checked at regular clinical and X-ray follow-up examinations (Fig.
5).
Within reason, delayed ZI insertion in regard of radiotherapy and/or primary ablative surgery would have been more hazardous and difficult, if not impossible. In turn, fixed dental restoration would have been more demanding, more lasting, suboptimal, even not feasible. Concisely, immediate insertion of ZI at the ablative tumour time could be considered as a biological investment.