Cone beam computed tomography (CBCT) of the treated sites was performed before augmentation procedure and 6 months postoperatively at time of reentry. Craniofacial bone and TM showed different radio-opacity, which allowed their easy differentiation on the scans after regulating the brightness and contrast. In our department, two different CBCTs were available (Accuitomo, J. Morita Corporation, Japan and 3D eXamVision, Kavo Dental GmbH, Germany). For large defects and in existence of possible other indications (e.g., sinus maxillary diagnostic), the 3D eXamVision was used. Small locoregional defects were imaged with the Accuitomo. Gained bone height and width was quantified using the KaVo-eXam Vision software (Kavo Dental GmbH, Germany) and One Volume Viewer software (J. Morita Corporation, Japan) on one descriptive slide of the CBCT scan [21]. Therefore, the margins of the basal and grafted bone and the rim of the TM were defined, and linear measurements for vertical and horizontal bone augmentation were made on one descriptive coronal section in a midalveolar position (Fig. 9). For horizontal bone augmentation, the widest horizontal distance in midalveolar position was evaluated. However, this evaluation technique has to be assessed critically as it is hard to distinguish between graft material and real new bone. A layer of soft tissue with some embedded granules underneath the mesh, which is usually removed at the time of implant insertion and mesh removal, could not be subtracted from the augmentation bone gain regularly.

The statistical analysis was performed using the IBM® SPSS® Statistics version 23.0 for Windows®. We report descriptive p values of tests, and no adjustment to multiple testing due to the low case number was performed. Chi-quadrat-test was performed to identify potential influencing factors for a higher risk of exposure of the TM.