Precision of 30 guided implants in complex tumour situations.

Implant born prosthetic rehabilitation of tumour patients can be difficult to perform. Challenges in treating such patients include disrupted anatomy with limited mouth opening due to previous ablative surgery as well as free-flaps or simple bone grafts, adjuvant therapy such as radiotherapy and, in general, poorer general health. Combining classical knowledge of ideal prosthesis placement and current virtual planning possibilities the positioning and in consequence the survival of dental implants can be optimised. Since prosthetic rehabilitation has a positive effect on the patients' quality of life and general health, we propose performing such surgeries as early as possible. All patients at our institution receiving pre-planned guided implant reconstruction and postoperative evaluation with Cone Beam Computed Tomography (CBCT) between 2015 and 2018 were evaluated for inclusion. Eight patients with a total of 30 implants met the inclusion criteria. The planned implant position was compared to the outcome position by fusing the two and deviations in entry-point position, apex-position, angular deviation and depth error were recorded. The mean (SD) discrepancy at entry-point was 2.28 (1.45) mm and 2.89 (1.53) mm at the apex, respectively. Mean (SD) angulation discrepancy was 9.5˚ (4.13˚) and the mean (SD) depth deviation was 1.52 (0.86) mm. Our results demonstrate the feasibility of pre-planned implant placement in challenging clinical situations and that only few concessions have to be made for precision.

Virtual planning, simultaneous dental implantation and CAD/CAM plate fixation: a paradigm change in maxillofacial reconstruction.

Prosthetic rehabilitation in patients undergoing reconstructive surgery using vascularized free flaps is challenging, and functional rehabilitation of the patient with a fixed prosthesis is rare. Virtually planned maxillofacial reconstruction including simultaneous dental implantation according to the prosthodontic ideal position of the implants could further enhance dental rehabilitation. The data of 21 patients undergoing fibula free flap reconstructive surgery with CAD/CAM patient-specific reconstruction plates during the years 2015-2018 were analysed, including the applicability of the virtual plan, flap survival, duration of surgery, ischemia time, simultaneous dental implantation, implant exposure, and postoperative complications. The virtual plan could be translated to surgery in all cases. In total, 76 dental implants were simultaneously placed during primary reconstruction in the 21 patients. For 38.1% of these patients, the implants could be uncovered in secondary surgery; the mean duration until exposure was 7.6 months. The implant survival rate was 97.4% (74/76). Wound infection requiring a secondary intervention occurred in 23.8% of patients during follow-up. Virtually planned reconstruction with a fibula free flap, simultaneous dental implantation, and CAD/CAM plates allows early and functional dental rehabilitation. A dental workflow should be integrated into the virtual planning, and prosthetically favourable implant positions should determine the position of the fibula segments.

Total virtual workflow in CAD-CAM bony reconstruction with a single step free fibular graft and immediate dental implants.

The Surgical reconstruction of defects of the face is challenging. Local and regional flaps have an important part to play, but large defects of bone and soft tissue are a greater problem. Microvascular tissue transfer has become the standard for such patients, and preoperative planning of bony reconstructions is now common. To use these preplanning tools best the implants should be placed in the prosthetically ideal place, and the bone positioned to surround the implants - that is, truly backward planning of the position of the bone. The buccolingual angulation and the actual position of the implants during operation can be difficult to verify. Using commonly available software and 3-dimensional printing solutions, therefore, we have constructed an algorithm to optimise the position of these implants during the operation, and to get their position as close to the planned outcome as possible. This algorithm is adaptable to any implant system and is potentially possible in any implant or preplanning software unit.

[Reconstructive orbital surgery]. / Rekonstruktive Orbitachirurgie.

BACKGROUND: In complex orbital reconstructions ideal positioning of the bony buttress and surrounding soft tissue is a prerequisite for an aesthetic and functional result. The use of computer-assisted surgery can support the surgeon before and during the reconstruction procedure and facilitate quality control processes. This is illustrated using three clinical examples. MATERIAL AND METHODS: The areas of interest (bony defect areas, surrounding tissues) are segmented in a 3D image series. In most cases, the contralateral non-affected side can serve as the reference in virtual reconstruction. The virtual model obtained can now be used for the manufacturing of patient specific models and implants, as well as for intraoperative navigation or direct quality control with the use of intraoperative cone beam computed tomography (CBCT). RESULTS: For the reconstruction of primary and secondary traumatic defects as well as for congenital malformations or neoplastic diseases, the presented workflow can be used. Preoperative virtual visualization, patient specific reconstruction and direct quality control using intraoperative CBCT ensure that the preoperatively planned result can be achieved. Together with the interplay of hard and soft tissue the best possible results can be achieved. CONCLUSION: Computer-assisted surgery has been continuously further developed over the last two decades and is currently used in the clinical routine. Patient specific implants in combination with the use of direct intraoperative quality control facilitate the reconstruction of complex orbital injuries and defects and enable the ideal reconstruction from both aesthetic and functional aspects.

Patient-specific biodegradable implant in pediatric craniofacial surgery.

Surgical correction of premature fusion of calvarial sutures involving the fronto-orbital region can be challenging due to the demanding three-dimensional (3D) anatomy. If fronto-orbital advancement (FOA) is necessary, surgery is typically performed using resorbable plates and screws that are bent manually intraoperatively. A new approach using individually manufactured resorbable implants (KLS Martin Group, Tuttlingen, Germany) is presented in the current paper. Preoperative CT scan data were processed in iPlan (ver. 3.0.5; Brainlab, Feldkirchen, Germany) to generate a 3D reconstruction. Virtual osteotomies and simulation of the ideal outer contour with reassembled bony segments were performed. Digital planning was transferred with a cutting guide, and an individually manufactured resorbable implant was used for rigid fixation. A resorbable patient-specific implant (Resorb X-PSI) allows precise surgery for FOA in craniosynostosis using a complete digital workflow and should be considered superior to manually bent resorbable plates.

Medium-term outcome of Astra Tech implants in head and neck oncology patients.

Rehabilitation with implant-retained prostheses is a key step in the rehabilitation of patients after ablative head and neck surgery. Data of patients who underwent mandibular restoration with Astra Tech implants were gathered consecutively and analyzed retrospectively. Implant survival was calculated by Kaplan-Meier analysis, and Cox models were used to identify any association between implant failure and contributing factors. In total, 136 implants were placed in 33 patients. The main reason for ablative surgery was squamous cell carcinoma. Twenty-one patients received adjuvant radiotherapy with a cumulative radiation dose of 56-76Gy prior to implantation. Failure occurred in six patients, resulting in the loss of 17 implants. The cumulative implant survival rate was 92.7% after 1 year and 87.5% after 20 months. Smoking and alcohol consumption were associated with a significantly higher implant failure rate. Most patients had a stable implant status after 20 months.