A suitable alternative surgical management of this particular case might have been to simply perform an alveoloplasty to produce the desired inter-occlusal clearance and proceed with placement of implant and simultaneous direct sinus lift. That would have left more of the apical portion of the implant within the grafted sinus and possibly modified the location of keratinized band of tissue. The location of the dental alveolar segment in relation to any antral septae also needs to be appreciated, as this described technique can be fraught with complication if such anatomical obstacles are not accounted for preoperatively .
The osteoperiosteal flap or “bone flap” commonly used in segmental orthognathic surgery is a bone fragment moved in space without detachment of the investing periosteum . The prerequisite for simultaneous implant placement in a vertical repositioning bone flap is adequate width within the transport segment. It is always a fine balance between allowing enough exposure to place the fixation device without significantly compromising periosteal vascular input into the bone segment. As it is well documented both clinically and experientially, full thickness mucoperiosteal releases will cause some degree of bone resorption at the labial plate .
Due to the presence of fixation plate and a sizeable sinus window, we decided to use a long-lasting resorbable membrane. In our experience and supported by the literature, placement of a membrane over the osteotomy site has been shown to increase the amount of bone formation . Considering we were only able to obtain one monocortical screw fixation on the mobilized portion of the maxillae, maintaining immobility during the critical phase of bone healing was an obvious liability. Animal studies which have investigated the biology of small segment wound healing have noted that after 2 weeks, revascularization of the small dento-osseous segment was noted . The cross application of such animal studies are helpful but do not completely capture the additional challenges in this case report. The studies in animals were looking at segmental dental alveolar segments which encompassed the natural teeth. In our case illustration, there were osteotomies made within the transport segment and healing of the overlying particulate allograft was contingent on biological stability of the respective segment. This is a clear illustration of how animal models can begin to provide a platform towards technical innovation, but there is always a parameter of uncharted terrain in translating to human clinical application.
A critical appraisal of the gingival architecture in the final end point of this case demonstrates some radiolucency through the soft tissue outlining the platform of the Nobel Biocare TiUnite implant. This would lead us to believe that either the transmucosal bone level placement attempt was inaccurate or excessive reflection of the labial tissue has caused some degree of resorption. This is another liability that needs to be carefully addressed if this application is recaptured within the esthetic zone. Perhaps slight subcrestal placement of the dental implant or platform switched body feature would minimize this outcome. In our application, we utilized an implant platform topography that is purported by the manufacture to allow soft tissue adhesion and minimize crestal bone loss.