A novel report on the use of an oncology zygomatic implant-retained maxillary obturator in a paediatric patient

The paediatric population rarely suffer malignant disease of the oral cavity requiring any form of maxillectomy, and there is little published evidence around the rehabilitation and restorative management of children undergoing such procedures. The seemingly most common approach for a limited low-level maxillary resection in a child would be to consider resection and simple prosthetic obturation as this allows relatively simple management of the tumour from a surgical point of view as well as immediate functional and aesthetic rehabilitation with a prosthesis. It also allows for full histopathological examination of the resected specimen to ensure complete resection of the tumour before committing the patient to any form of complex surgical reconstruction which could be planned at a later date should the patient wish. The delivery of a maxillary obturator improves quality of life significantly by primarily restoring aesthetic and functional modalities. It also serves as a purpose to allow correct phonation of speech, prevent nasal discharge of masticatory contents and facilitate swallowing. The aesthetic and psychological benefits of facial restoration are paramount in a child undergoing such a procedure. The use of microvascular reconstruction techniques have allowed for autogenous tissue reconstruction of maxillary defects with either soft or hard tissue. The use of a soft-tissue-only reconstruction such as a radial forearm flap in this clinical situation would prevent successful dental rehabilitation as the soft tissue flap provides no support for the dental prosthesis and, apart from the separation of the oral and nasal cavities, provides no advantage for the patient. The use of a composite-bone-containing flap such as the fibula flap has the potential to provide oro-nasal separation as well as bone to support an implant-retained prosthesis, and with the latest digital technologies, this can be provided rapidly in carefully selected cases [8], although this mode of rapid rehabilitation is not available in many centres. However, there is no published data on this mode of dental rehabilitation in a growing child currently, and this approach should probably be deferred until all mandibular growth has been completed. The use of microvascular reconstruction, in addition, carries with it significant clinical risks as well as potential donor site morbidity and flap failure as well as the potential for fibrous union and loss of individual bony segments where multiple osteotomies are required.

The difficulty of restoration with a maxillary obturator prosthesis depends on the extent of the surgical resection, with the acceptance that resections with an increasing horizontal component provide a much greater prosthodontic challenge. The number of remaining teeth is a key component in conventional obturator design [9] with the remaining dentition being used exclusively to retain the prosthesis by means of clasps which are often in the visual field and affect the resulting aesthetic outcome for the patient as well as placing significant forces onto them. In conventional maxillary defect preparation, the additional use of a split skin graft into the lateral aspect of the cheek is used to provide a scar band to aid with defect retention, and this brings added morbidity to the procedure especially for a paediatric patient. In conventional hemi-maxillectomy cases, gaining some form of retention from the defect is essential in providing the patient with confidence in the use of the prosthesis, and the discomfort associated with this can make paediatric patients anxious about placing and removing the obturator themselves. The advantages of providing “in-defect” support and retention by means of zygomatic implant placement addresses all of these potential difficulties and allows the construction of a simple highly polished acrylic prosthesis that does not require clasping of the teeth in the aesthetic zone, requires very little extension into the defect to affect a peripheral seal and most of all provides good support when the patient masticates on the defect side. No additional skin grafting is required, and the placement and retrieval of the prosthesis is comfortable and atraumatic. Maintenance of the prosthesis is simple with modifications to the peripheral seal as required at the chair side and replacement of the bar attachments from time to time.

In a paediatric patient, the development and subsequent growth of facial skeleton is an added concern, although by age 13/14, the major mid-face growth will be largely completed [10]. Certainly in this case, the bone volume of the zygomatic body was more than adequate for the placement of the implants. In terms of ongoing facial growth, Min Kim et al. report a case where an 11-year-old male underwent a hemi-maxillectomy and a modified functional obturator (MFO) prosthesis was successfully used to obturate the defect and restore aesthetics and function. After 18 months of wearing the MFO, the result was stable, and at 3 years post-operatively, the patient’s facial profile was reported as near normal. In the case reported here, it was felt that due to the removable nature of the obturator prosthesis, the implant technique employed would allow for the construction of a new maxillary obturator in the event of any significant continued mid-facial/maxillary growth, which so far has not been required.

The use of modified zygomatic implants (Fig. 1) allows improved hygiene by the patient of the implants within the maxillary defect. The threaded portion of the implants is fully engaged into the bone with only the smooth portion protruding into the defect. Clearly this ongoing hygiene by the patient is of utmost importance in preventing peri-implant soft and hard tissue changes, but the implant design here has facilitated that extremely well in this young patient, and no additional professionally directed hygiene measures to maintain excellent peri-implant health have been required to date.

The evidence for loading zygomatic implants immediately is very clear in the literature [11] in a cross-arch manner but not in a unilateral situation as has been utilised in this case. Whilst the stability of the implants achieved at surgery was excellent, it was decided to adopt a delayed loading approach which also gave time for the maxillectomy defect to stabilise prior to the construction of the definitive prosthesis.