Prosthetic digital solutions for the reconstructed mandible after cancer surgery: preliminary results of ongoing research.

Background After cancer ablative surgery of the mandible, the fibula results not thick enough to reach the original height of the native alveolar bone of the mandible. As a consequence, positioning of dental implants is often deeper then the mouth floor, and unaesthetic and inappropriate hygienic maintenance may outcome with the final prosthetic restoration. Aim of this study is to discuss a novel approach to the positioning of the Fibula Free Flap (FFF) as a function of the restoration of the vertical height of the mandible, for improving the natural gingival/crown ratio and consequently the oral hygiene maintenance of the prosthetic rehabilitation. Moreover, the secondary aim is to present the hybrid (fixed and removable) approach to the prosthetic restoration. Methods and Materials In this novel protocol the design of the bone plate was modified to allow reproducing a double-level anatomy: the more lateral/basal bone inferior margin of the mandible and the more medial alveolar bone position. The customized plate is projected to support the FFF at the higher position of the alveolar bone level, so that no pink resin body of the prosthesis is projected to fill the discrepancy between teeth crowns and the gingiva. The cobalt/chrome framework is then prototyped using a hybrid manufacturing machine, and a new concept of connection to implants is used to fix the prosthesis in place: a double-option attachment allowed using the prosthesis both as a removable or fixed restoration. Results This new methodology allows giving a physiologic gingival appearance to the prosthetic rehabilitation without any additive pink resin to recover the missing alveolar bone and mucosa. The digital workflow permits the transfer of occlusal, aesthetic, and functional data from the pre-operative status of the patient to the final design of the rehabilitation. Moreover, the double-option attachments used for the prosthetic connection to implants permitted to use the restoration as a removable or fixed prosthesis, depending on the home care maintenance results of each patient, avoiding the risk of reactive gingival hyperplasia. Conclusion This novel protocol, due to the new design of the customized bone plate, allowed maintaining the face profile and a correct alveolar bone volume of the mandible, restoring the occlusion without artificial crossbite and excessive crown/implant ratio with consequent usage of large volume of pink resin prosthetic body. Moreover reactive gingival hyperplasia may be avoided using the double option abutment on implants that allow using the prosthesis both as removable or fixed restoration, depending on the oral hygienic maintenance ability of the patient.