Background : Oral dental rehabilitation after ablative surgery in head and neck cancer is demanding. Besides soft tissue deficiencies due to resection and scarring, bony reconstruction has an important impact on functional and aesthetic result. Limited bone graft dimensions restrict adequate oral rehabilitation with dental implants. Disproportions between soft and hard tissue result often in later periimplantitis and early implant loss. Pre-operative virtual planning in mandible reconstruction could ease predictable oral rehabilitation.
Methods : After import of 3D images (CT or CBCT scan) into iPlan 3.0 ® (Brainlab ® , Germany), automated atlas-based segments of the mandible are created to add missing or destructed parts including a virtual dental arch. Depending on the position of the teeth in the upper jaw, ideal implant position for the mandible are simulated by using hollow cylinders, that represent implant axis and diameter, as well as the ideal amount of peri-implant bone. For two-stage procedures, a stereolithographic biomodel is created to allow for bending an ideal patient specific reconstruction plate, which guides the future bone position.
Results : There is a significant discrepancy between conventional bent mandible reconstruction plates, primarily aligned to the outer contour of the original mandible, compared to backwards planned reconstruction plates, that takes the ideal oral rehabilitation into account. Especially in the posterior molar region, the patient specific reconstruction plate is located more on the lingual side to prevent cross-bite situation of implant borne prosthesis.
Conclusion : Virtual planned reconstruction plates could guide the future position of bone grafts and thus allow for ideal oral rehabilitation with dental implants. Since planning is not primarily dependent on the outer contour of the mandible, improved functional rehabilitation could come along with minor aesthetic results. This has to be discussed with the patient prior to surgery.
Key words: mandible reconstruction; virtual planning; computer-assisted planning