Page 67 - Craniomaxillofacial Implant Surgery - Jeroen P.J. Dings

Extra-oral implants – insertion per- or post-ablation?
INTRODUCTION
Maxillofacial defects may be the result of malformative or infective processes, trauma, or oncologic therapy. Most maxillofacial defects have an oncology-related origin, resulting in multiple functional, esthetical, and psychosocial difficulties1-3.
As replacement of an eye or nose by solely surgical means often results in a less
cosmetic outcome compared with prosthetic rehabilitation, a prosthetic device is
often chosen1,2,4-8. Understandably, mechanical retention of the prosthetic device is
crucial. Conventionally, retention was achieved by using skin adhesives, obtaining
hard and soft tissue undercuts, or attachment to glasses1,4,9-11. Since the success of
intraoral endosseous implants, the osseointegration concept has also been introduced 4 in maxillofacial defects, as it offers better predictability, prosthetic adaptability, and
esthetics, resulting in higher convenience for patients12-14. Of utmost importance, in contrast with surgical reconstructions, prostheses allow cavities to be accessed for inspection of possible tumor recurrences9,15. Moreover, implant-supported extraoral prostheses, also called epitheses, have been shown to improve patient acceptance, level of function, and quality of life1,4,5,9,16-22. Disadvantages include the necessity of prosthetic and implant maintenance, periodic replacement of prostheses, and the risk of implant dislodgement when overloaded13.
Although the use of osseointegrated implants is an accepted treatment modality, many aspects in relation to oncologic therapy remain controversial, such as favorable time of placement and the role of hyperbaric oxygen (HBO) in case radiation therapy is applied23. In addition, implant survival is reported to be site specific and, amongst others, related to associated stress distribution at the bone–implant interface, irradiation dose, and fractionation8,13,16,18,24.
There are only a few studies determining the optimal timing of implant placement in relation to ablative surgery. The objective of the present study was to evaluate differences in survival time between extra-oral implants placed during ablation (DA- implants) of nose or orbit, compared to those placed in a later stage, the socalled after ablation (AA-) implants. The second objective is to determine differences in survival rate for implants placed before irradiation compared to implants, which are placed in already irradiated bone.
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