DISCUSSION
The ambition to restore ad integrum the lost oral structures
often leads us to select a fixed implant-supported option. Clinicians
thus hope to restore esthetics, function and comfort for these
edentulous patients. However, this vision is often unrealistic in a
context of UADT cancer. The clinical conditions of the prosthetic
management, the need for an easy access to oral hygiene, but also for
the supervision of possible cancer recurrence on the surgically treated
sites modify the prosthetic choice. Studies have shown (3) that patient
satisfaction would be equivalent between patients wearing a complete
implant-supported bar-retained overdenture or a fixed implant-supported
prosthesis. Moreover, oral hygiene maintenance (often difficult in
patients treated surgically for UADT cancers) is easier with a complete
implant-supported bar-retained overdenture compared to a fixed implant
supported prosthesis.
In these complex clinical situations, the limited mouth opening
(LMO) restricts easy access to prostheses. Excessive retention of the
clips must be avoided despite the great number of implants. Therefore,
we will prefer the Dolder CB rather than the Hader CB.
The CBs were made of titanium for all our clinical cases because
titanium CBs achieve better stress distribution on implants and
peri-implant tissues than the cobalt-chromium CBs (13).
The main difficulty of the prosthetic rehabilitation is the vertical
dimension paradox : Patient N°1 presented a severe bone resorption, and
Patient N°2 had an oversized reconstruction. Initially, for both cases,
we could therefore expect an increased prosthetic space ; however, given
the microstomia / mouth opening limitation (and the oversized fibula in
the mandible for Case N°2), the prosthetic space is reduced. Therefore,
determining an esthetic and functional VOD becomes difficult. Tissue
sclerosis leads to labial inocclusion at rest which can prove to be
unesthetic. In Case N°2, this tissue sclerosis could have been limited
if we had implemented a complete removable prosthesis immediately after
the surgery. But, given the context (fibula graft/ UADT cancer), placing
a prosthesis immediately after the surgery could lead to flap necrosis.
The complete removable bar-retained overdenture remains a good
alternative to the esthetic challenge (lip support, gummy smile) often
observed in patients treated surgically for UADT cancer.
Another problem frequently encountered (15) in patients grafted with a
fibula is mucosal hypertrophy around the implants. It consists of
granulomatous mucous tissue which may complicate the implant-supported
prosthetic rehabilitation (16). In Case N°2, we could have considered
achieving a bar contacting the mucosa in order to reduce the stress on
the implants and the bar. However, this option limits the access for
good oral hygiene, and may aggravate peri-implant tissue proliferation
which can become chronic. Grafting palatal gingiva in the concerned
zones could be an alternative.
For Patient N°1, in the maxilla, we fabricated a CB spaced 1mm from the
mucosa because his oral hygiene was good despite the limited mouth
opening (LMO) and microstomia, but also to limit the stress on the
peri-implant bone. Otherwise, we could have fabricated a complete
prosthesis with full palate coverage. Indeed, Kim MJ and Hong SO showed
that a prosthesis with full palate coverage provided a better stress
distribution on the implants (particularly the most distal ones which
receive the most of the loads), than a partial palate coverage). (18)