Rutger H. Schepers

Fully 3‐dimensional digitally planned reconstruction of a mandible with a free vascularized fibula and immediate placement of an implant‐supported prosthetic construction

Reconstruction of craniofacial defects becomes complex when dental implants are included for functional rehabilitation. We describe a fully 3‐dimensional (3D) digitally planned reconstruction of a mandible and immediate prosthetic loading with a fibula graft in a 2‐step surgical approach.

Splintless surgery: does patient-specific CAD-CAM osteosynthesis improve accuracy of Le Fort I osteotomy?

To analyse the accuracy of maxillary positioning after Le Fort I osteotomy, we retrospectively assessed the outcome in three patients (mean (range) age 40 (21 - 60) years) who had been treated with patient-specific CAD-CAM osteosynthesis plates as part of a bimaxillary osteotomy. Virtual surgical planning in each case was based on cone-beam computed tomography (CT) (Simplant® O&O, Dentsply Implants NV, Kessel-Lo, Belgium), and patient-specific CAD-CAM drilling guides and osteosynthesis plates were produced for maxillary positioning and fixation. We evaluated the accuracy of the placement by virtual comparison of the preoperative and postoperative images. In the upper dentition, postoperative analysis showed a mean (SD) deviation of 1.3 (1.4) mm from the preoperative plan. The method enables accurate placement of the maxilla, independent of the condyle or mandible, without the need for extraoral reference points.

Integration of oncologic margins in three-dimensional virtual planning for head and neck surgery, including a validation of the software pathway

PURPOSE Three-dimensional (3D) virtual planning of reconstructive surgery, after resection, is a frequently used method for improving accuracy and predictability. However, when applied to malignant cases, the planning of the oncologic resection margins is difficult due to visualisation of tumours in the current 3D planning. Embedding tumour delineation on a magnetic resonance image, similar to the routinely performed radiotherapeutic contouring of tumours, is expected to provide better margin planning. A new software pathway was developed for embedding tumour delineation on magnetic resonance imaging (MRI) within the 3D virtual surgical planning. MATERIAL AND METHODS The software pathway was validated by the use of five bovine cadavers implanted with phantom tumour objects. MRI and computed tomography (CT) images were fused and the tumour was delineated using radiation oncology software. This data was converted to the 3D virtual planning software by means of a conversion algorithm. Tumour volumes and localization were determined in both software stages for comparison analysis. The approach was applied to three clinical cases. RESULTS A conversion algorithm was developed to translate the tumour delineation data to the 3D virtual plan environment. The average difference in volume of the tumours was 1.7%. CONCLUSION This study reports a validated software pathway, providing multi-modality image fusion for 3D virtual surgical planning.

Comparing Two Diagnostic Procedures in Planning Dental Implants to Support a Mandibular Free-Ending Removable Partial Denture

BACKGROUND The use of a cone beam computed tomography (CBCT) for the preoperative implant planning is increasing. A clear guideline is needed in which cases of CBCT is essential. PURPOSE In this study, two imaging modalities (panoramic radiograph and CBCT) are compared in preoperative implant planning in the severely resorbed mandible and the influence on the observers assessments. MATERIALS AND METHODS Thirty-four consecutive patients with bilateral edentulous regions in the mandible were included. The feasibility of implant placement in the premolar and molar region was judged by three observers on basis of casts either with a panoramic radiograph or a CBCT.Cohens kappa, sensitivity and specificity rates, odds of agreement and disagreement as well as the odds ratios (ORs, ratio between odds of agreement and disagreement) were calculated per observer and overall for all observers assuming the majorities agreement as the prevailing opinion. RESULTS Overall outcome for premolar region revealed true-positive and true-negative rates of 90% and 0%, respectively, with Cohens kappa (κ) = -0.04. The ORs for the three observers varied between 2.6 and 158.8, with an overall OR = 76.For the molar region, overall true-positive and true-negative rates were 65% and 22% respectively, with Cohens κ = 0.68, representing a reasonable amount of agreement. Sensitivity and specificity as well as the ORs for individual observers were fairly consistent with an overall OR = 43. CONCLUSION Implant placement in the resorbed posterior mandible can be well assessed with a cast in combination with a panoramic radiograph in the vast majority of the cases. Misclassification amounts to approximately 10% to 13%. In all cases of misclassification, a critical bone height, or an unclear course of the mandibular nerve or a knife edge ridge was present. In these cases, the use of a CBCT is justified.

The design, production and clinical application of 3D patient-specific implants with drilling guides for acetabular surgery

An innovative procedure for the development of 3D patient-specific implants with drilling guides for acetabular fracture surgery is presented. By using CT data and 3D surgical planning software, a virtual model of the fractured pelvis was created. During this process the fracture was virtually reduced. Based on the reduced fracture model, patient-specific titanium plates including polyamide drilling guides were designed, 3D printed and milled for intra-operative use. One of the advantages of this procedure is that the personalised plates could be tailored to both the shape of the pelvis and the type of fracture. The optimal screw directions and sizes were predetermined in the 3D model. The virtual plan was translated towards the surgical procedure by using the surgical guides and patient-specific osteosynthesis. Besides the description of the newly developed multi-disciplinary workflow, a clinical case example is presented to demonstrate that this technique is feasible and promising for the operative treatment of complex acetabular fractures.

Calculating nasoseptal flap dimensions: a cadaveric study using cone beam computed tomography

We hypothesize that three-dimensional imaging using cone beam computed tomography (CBCT) is suitable for calculating nasoseptal flap (NSF) dimensions. To evaluate our hypothesis, we compared CBCT NSF dimensions with anatomical dissections. The NSF reach and vascularity were studied. In an anatomical study (n = 10), CBCT NSF length and surface were calculated and compared with anatomical dissections. The NSF position was evaluated by placing the NSF from the anterior sphenoid sinus wall and from the sella along the skull base towards the frontal sinus. To visualize the NSF vascularity in CBCT, the external carotic arteries were perfused with colored Iomeron. Correlations between CBCT NSFs and anatomical dissections were strongly positive (r > 0.70). The CBCT NSF surface was 19.8 cm2 [16.6–22.3] and the left and right CBCT NSF lengths were 78.3 mm [73.2–89.5] and 77.7 mm [72.2–88.4] respectively. Covering of the anterior skull base was possible by positioning the NSF anterior to the sphenoid sinus. If the NSF was positioned from the sella along the skull base towards the frontal sinus, the NSF reached partially into the anterior ethmoidal sinuses. CBCT is a valuable technique for calculating NSF dimensions. CBCT to demonstrate septum vascularity in cadavers proved to be less suitable. The NSF reach for covering the anterior skull base depends on positioning. This study encourages preoperative planning of a customized NSF, in an attempt to spare septal mucosa. In the concept of minimal invasive surgery, accompanied by providing customized care, this can benefit the patients’ postoperative complaints.

Liftingprocedures in de cosmetische aangezichtschirurgie

A prominent characteristic of the aging face is the descent of skin and subcutaneous tissues. In order to reduce this and create a more youthful appearance, several lifting procedures can be employed. In the forehead and eyebrow region the transblepharoplastic brow lift, the direct brow lift, the temporal brow lift, the coronal brow lift and the endoscopic brow lift can be distinguished. For the mid-face, the facelift is known to be an effective treatment for aging characteristics. Classic facelifts can be divided into the one layer-, two layer- and the deep plane facelift. Nowadays the minimal access cranial suspension lift is popular. The lifting capacity of this lift may be less, but the risk of complications is lower and the result is often more natural. A neck lift improves the chin-neck angle and a submental liposuction/lipectomy can contribute to this. Complications in lifting procedures are rare. Hematoma is the most frequent complication. Skin necrosis of the wound edges and laceration of the end branches of the facial nerve can also occur. There is a tendency towards minimally invasive procedures with smaller risk of complications and shorter recovery periods.

Optimisation of three-dimensional lower jaw resection margin planning using a novel Black Bone magnetic resonance imaging protocol

Background MRI is the optimal method for sensitive detection of tumour tissue and pre-operative staging in oral cancer. When jawbone resections are necessary, the current standard of care for oral tumour surgery in our hospital is 3D virtual planning from CT data. 3D printed jawbone cutting guides are designed from the CT data. The tumour margins are difficult to visualise on CT, whereas they are clearly visible on MRI scans. The aim of this study was to change the conventional CT-based workflow by developing a method for 3D MRI-based lower jaw models. The MRI-based visualisation of the tumour aids in planning bone resection margins. Materials and findings A workflow for MRI-based 3D surgical planning with bone cutting guides was developed using a four-step approach. Key MRI parameters were defined (phase 1), followed by an application of selected Black Bone MRI sequences on healthy volunteers (phase 2). Three Black Bone MRI sequences were chosen for phase 3: standard, fat saturated, and an out of phase sequence. These protocols were validated by applying them on patients (n = 10) and comparison to corresponding CT data. The mean deviation values between the MRI- and the CT-based models were 0.63, 0.59 and 0.80 mm for the three evaluated Black Bone MRI sequences. Phase 4 entailed examination of the clinical value during surgery, using excellently fitting printed bone cutting guides designed from MRI-based lower jaw models, in two patients with oral cancer. The mean deviation of the resection planes was 2.3 mm, 3.8 mm for the fibula segments, and the mean axis deviation was the fibula segments of 1.9°. Conclusions This study offers a method for 3D virtual resection planning and surgery using cutting guides based solely on MRI imaging. Therefore, no additional CT data are required for 3D virtual planning in oral cancer surgery.

Multi-modality 3D mandibular resection planning in head and neck cancer using CT and MRI data fusion: A clinical series

OBJECTIVES 3D virtual surgical planning (VSP) and guided surgery has been proven to be an effective tool for resection and reconstruction of the mandible. Currently, most widely used 3D VSP approaches to mandibular resection do not include detailed tumour information in the VSP. This manuscript presents a strategy where the aim was to incorporate tumour visualisation into the 3D virtual plan. Three-dimensional VSP of the mandibular resections was based on the fusion of CT and MRI data which was subsequently applied in clinical practice. METHODS All patients diagnosed with oral squamous cell carcinoma between 2014 and 2017 at the University Medical Centre Groningen were included. The tumour was delineated on the MRI data, after which this dataset was fused with the CT bone data in order to construct a 3D bone and tumour model for virtual resection planning. Guided resections were performed and post-operative evaluation quantified the accuracy of the resection. The histopathological findings and patient and tumour characteristics were compared to those of a historical cohort (2009-2014) of conventional mandibular continuity resections. RESULTS Twenty-four patients were included in the cohort. The average deviation from planned resection was found to be 2.2 mm. Histopathologic analysis confirmed all resection planes (bone) were tumour free, compared to 96.4% in the historic cohort. CONCLUSION MRI-CT base tumour visualisation and 3D resection planning is a safe and accurate method for oncologic resection of the mandible. It is an improvement on the current methods reported for 3D resection planning based solely on CT data.

Cosmetische ingrepen tijdens orthognathische chirurgie

The goal of a combined orthodontic-surgical treatment is to correct the dysgnathia and malocclusion and thereby achieve an improvement of function. As a supplement to osteotomy, enhancement of facial aesthetics is increasingly being used to gain more harmony in the face and/or to achieve facial rejuvenation. In this regard, one might think of contour- or projection improvement by performing an intra-oral zygoma osteotomy or the placement of an alloplastic implant. By means of lipofilling, changes to the contours of the soft tissue can be realised. A sub mental fat surplus can be corrected by liposuction or lipectomy, resulting in a normalisation of the chin-neck angle. Otoplasty and limited rhinolplasty can also be combined with an osteotomy, while a blepharoplasty and a lip lift for older patients can be applied for facial rejuvenation. These aesthetic corrections can often be performed in the same surgical session as the osteotomy and contribute to significant patient satisfaction.