Fig. 36.6 Good skin graft leaving the tragus. (a) Healed surgical site. (b) Prosthesis

Summary: Adhesive and/or Mechanically Retained Orbital Prosthesis

•Orbital prosthesis replaces globe, contents of the orbit, and surrounding tissue.

36.5Adhesive and/or Mechanically Retained Orbital Prosthesis

The loss of the globe and surrounding contents of the orbit poses significant challenges as regards rehabilitation with an orbital prosthesis. This area in particular seems to be rife with confusion as to how to provide the best surgical management in regard to creating the ideal site for prosthetic management. Not infrequently, the patient having an orbital exenteration is seen by the Maxillofacial Prosthodontist only after tumor resection. The orbital defect is not uncommonly managed with free tissue transfer that obliterates the depth of the socket making it difficult if not impossible to place an orbital prosthesis that would represent restoration of symmetry and harmony to the facial contours. As previously noted, if the patient is afforded the opportunity to consult with the Prosthodontist prior to doing an orbital exenteration, this discussion could preclude the unfortunate circumstance of having to subject the patient to further surgical intervention or indicating that prosthodontic management is not possible.

From the prosthodontic perspective, lining the orbital socket with a split-thickness skin graft leaving a firm tissue base and deep, dry socket creates an ideal cavity for which an orbital prosthesis can be successfully provided [4] (see Fig. 36.8a). Sometimes, fullthickness coverage of the exenterated orbit is needed especially when post-op radiotherapy is planned.

There are occasions where orbital exenteration is combined with a maxillectomy for those tumors

emanating from the maxillary sinus and eroding through the floor of the orbit. In general terms, the rehabilitation of such cases necessitates working from the inside out as the maxillary obturator or free flap reconstruction of the maxillectomy impacts the facial contours. This internal contouring of the facial anatomy needs to be established prior to developing the craniofacial prosthetic component of such patients’ rehabilitation efforts.

Typically, the big departure between an ocular prosthesis for a patient missing the globe vs. that for an individual treated with an orbital exenteration is the requirement to have the ocular prosthesis for the latter be smaller and crescent-shaped for ease in placement and removal. Such a design/contour element of the ocular component of the silicone orbital prosthesis thereby prevents the prosthesis from becoming torn or damaged.

The major challenge for successful orbital rehabilitation is first and foremost to accurately orient the ocular component of the prosthesis to establish the appropriate “gaze.” Given that the ocular component of an orbital prosthesis does not track, its three-dimen- sional spatial orientation needs to be precisely placed to afford symmetry in relation to the globe on the unaffected side. This cornerstone in fabrication is critical for arriving at a completed prosthesis that accurately represents restoration of normalized appearance (see Fig. 36.8b).

In some circumstances, the orbital cavity presents with undercuts posterior and superior to the superior orbital

rim and posterior and inferior to the infraorbital rim. Such a presentation can lend itself to the fabrication of a twopiece mechanically retained orbital prosthesis [5].

When implants are used to retain the orbital prosthesis, the space requirements needed for placement of the retaining elements for the prosthesis, be they independent or splinted, can challenge the positioning of the ocular component in its mandated and correct three-dimensional spatial orientation. This challenge can often result in the need for some creative engineering to accommodate and satisfy both form and retention requirements.

Summary: Midface/Multisite Craniofacial

Prosthesis

•Facial prostheses that extend beyond one anatomic site.

36.6Midface/Multisite Craniofacial Prosthesis

When facial anatomy compromise extends beyond one anatomic site, e.g., orbit/nose, orbit/cheek, nose/ upper lip, etc., the need for craniofacial prosthetic rehabilitation becomes significantly more challenging and complex. Further, a combination intra/ extra oral anatomical compromise such as that for

an individual undergoing a maxillectomy and orbital exenteration, planning, and facilitation of such rehabilitation efforts extend beyond those of multi-facial site compromises [6]. Each of these situations tends to be unique and challenges the rehabilitation efforts and creativity of the individual providing such a service. Given the highly variable presentations of such treatment requirements makes it difficult to identify specific issues to address in this section. The necessity for combined intraoral/extraoral defect management to be planned and facilitated from inside out is an absolute requirement for this type of rehabilitation effort. Use of magnet retention is another technique for retaining prosthesis (see Fig. 36.9a–c).

For the combination craniofacial defects, the remaining anatomy must be viewed from the perspectives of where support, stability, and retention can be achieved by either engaging soft tissue undercuts (to do so is concerning for the radiated patient), use of adhesives, or possibly planning for use of craniofacial implants. The challenge for all craniofacial prosthetic rehabilitation efforts from the perspective of patients in need of such treatment, first and foremost, is the provision of a predictable retention system for prosthesis [7, 8]. The more anatomical compromise needing to be addressed, the more challenging it is to create an adequate retention system. Generally speaking, the larger facial anatomical malignancy mandates multimodality therapeutic interventions. Therefore, most of

these patients have been treated with high doses of radiation with or without concomitant or adjunctive chemotherapeutic agents. Thus, the tissue base separate and apart from the surgical intervention is compromised and likely can be negatively impacted by daily use of adhesives to retain the prosthesis or pressure atrophy in sites where soft tissue undercuts are engaged by the prosthesis. Further, use of craniofacial implants can also be compromised in regard to either establishing a good bone/implant osseointegrated interface or over time become compromised by the latent long-term effects of radiotherapy on the tissue bed. All in all, achieving a suitable retention system for such situations, in and of itself, is challenging above and beyond creating a pleasing restoration of anatomical loss.

Summary: Considerations Regarding Implant

Retained Craniofacial Prosthesis

•Osseointegrated implants are used for increasing the stability of craniofacial prostheses.

36.7Considerations Regarding Implant Retained Craniofacial Prosthesis

Much like the requirements for adhesive retained facial prostheses, each treatment site for craniofacial implant retained prostheses has parameters for consideration in regard to optimizing implant placement and tissue base management. The common thread for implant retained