In the present study, a newly introduced bovine cross-linked collagen scaffold (test material) was investigated in vivo in an Achilles tendon defect model and compared to a commercially available porcine collagen scaffold (control material). In total, 28 male Sprague Dawley rats (about 400 g) were examined. The defined Achilles tendon defect of 5 mm of the right hind limb was replaced by one of the scaffold materials. After euthanasia, the hind limbs were transected for testing. Biomechanical evaluation was carried out via tensile testing (n = 8 each group, observation time: 28 days). Nonoperated tendons from the bilateral side were used as a control (native tendon, n = 4). For the histological evaluation, 12 animals were sacrificed at 14 and 28 days postoperatively (n = 3 each group and time point). Stained slices (Hematoxylin & Eosin) were evaluated qualitatively in terms of presence of cells and cell migration into scaffolds as well as structure and degradation of the scaffold. All transected hind limbs were additionally analyzed using MRI before testing to verify if the tendon repair using a collagen scaffold was still intact after the observation period. The maximum failure loads of both scaffold materials (test material: 54.5 ± 16.4 N, control: 63.1 ± 19.5 N) were in the range of native tendon (76.6 ± 11.6 N, p ≥ 0.07). The stiffness of native tendons was twofold higher (p ≤ 0.01) and the tear strength was approximately fivefold higher (p ≤ 0.01) compared to the repaired tendons with both scaffolds. Histological findings indicated that neither the test nor the control material induced inflammation, but the test material underwent a slower remodeling process. An overall repair failure rate of 48% was observed via MRI. The experimental data of the newly developed test material showed similar outcomes compared to the commercially available control material. The high repair failure rate indicated that MRI is recommended as an auxiliary measurement tool to validate experimental data.

In the field of dental technology, the length of ceramic pontics is limited to avoid mechanical failure. To reduce thermal-induced residual stress within the ceramic, using smaller subcomponents and subsequent bonding with silicate-based glass solder may be a favorable approach. Thus, the bending strength of zirconia compounds bonded with different silicate-based glass solders was investigated. For this purpose, rectangular specimens made of zirconia were bonded by glass solder. Parameters such as the scarf angle (45° and 90°), two different glass solders, as well as the soldering process (pressure and surface treatment) were varied. All specimens were subjected to quasi-static four-point bending tests according to DIN EN ISO 843-1. Additionally, the quality of the glass solder connection was evaluated using μCT and fractography. In the present study, zirconia compounds were sucessful bonded of zirconia compounds using silicate-based glass solder was. No significant differences in terms of bending strength were observed with respect to the different bonding parameters analyzed. The highest bending strength of 130.6 ± 50.5 MPa was achieved with a 90° scarf angle combined with ethanol treatment of the specimens before soldering and an additional application of a pressure of 2 bars in a dental pressure pot before subsequent soldering. Nevertheless, the bending strengths were highly decreased when compared to monolithic zirconia specimens (993.4 ± 125.5 MPa).

Purpose Zirconium dioxide ceramic has been successfully introduced as a framework material for fixed dental prostheses. To reduce manufacturing constraints, joining of subcomponents could be a promising approach to increase the mechanical performance of long‐span fixed dental prostheses. In this experimental study, the biomechanical behavior of monolithic and soldered framework specimens for fixed dental prostheses made of Y‐TZP was investigated. Materials and methods Framework specimens (n = 80) of 5‐unit fixed dental prostheses made of Y‐TZP were prepared and divided into 10 equal groups. The specimens were monolithic or composed of subcomponents, which were joined using a silicate‐based glass solder. Thereby, three joint geometries (diagonal, vertical with an occlusal cap, and dental attachment‐based) were investigated. Moreover, the groups differed based on the mechanical test (static vs. dynamic) and further processing (veneered vs. unveneered). The framework specimens were cemented on alumina‐based jaw models, where the canine and second molar were acting as abutments before a point‐load was applied. In addition, µCT scans and microscopic fractography were used to evaluate the quality of soldered joints and to determine the causes of fracture. Results The determined fracture loads of the different unveneered framework specimens in static testing did not vary significantly (p = 1). Adding a veneering layer significantly increased the mechanical strength for monolithic framework specimens from 1196.29 ± 203.79 N to 1606.85 ± 128.49 N (p = 0.008). In case of soldered specimens with a dental attachment‐based geometry, the mechanical strength increased from 1159.42 ± 85.65 N to 1249.53 ± 191.55 N (p = 1). Within the dynamic testing, no differences were observed between monolithic and soldered framework specimens. µCT scans and fractography proved that the dental attachment‐based joining geometry offers the highest quality. Conclusion Using glass soldering technology, subcomponents of 5‐unit framework specimens made of Y‐TZP could be joined with mechanical properties comparable to those of monolithic frameworks.

Currently used methods for processing allogeneic bone grafts like gamma irradiation are connected with downside of altering the mechanical properties of the graft. As an alternative, high hydrostatic pressure (HHP) leads to an effective devitalization of cells without influencing the bone matrix and its mechanical behavior. To address the clinical application, bone plates were prepared out of HHP-treated bone granules, which are conceivable for augmentations in the jaw region. In order to achieve sufficient mechanical strength, two different adhesives were tested. Mechanical characterization by three-point bending tests was performed. Furthermore, analysis regarding cytotoxicity as well as colonization experiments with mesenchymal stem cells were performed to investigate osteoconductive properties of the bone plates. While plates composed of fibrin glue showed better biocompatibility, plates prepared with Loctite® 408 showed better mechanical properties and could be incorporated in a model application. Regardless of the adhesive, bone plates induced osteogenic differentiation compared to cells cultured without bone plates. Although an adhesive combining both properties would be necessary for later clinical application, the study at hand demonstrates the possibility of producing allogeneic bone plates from HHP-treated granules, which meet the basic requirements for jaw augmentation.