Background: This study investigated whether patient-specific condylar positioning devices (CPDs) are beneficial compared to the conventional manual positioning of the condyles. Methods: In this prospective, randomized trial, patients undergoing orthognathic surgery with a bilateral sagittal split osteotomy of the mandible were included. The ascending ramus was positioned with computer-aided designed and computer-aided manufactured (CAD/CAM) patient-specific devices in the CPD group and manually in the control group. Postoperatively, cone-beam computed tomography (CBCT) was performed to align the virtually planned position with the postoperative result. Results: Thirty patients were enrolled in the study, with 14 randomized to the CPD group and 16 to the control group. In the CPD group, the ascending ramus differed in the postoperative CBCT scan from the virtually planned position by 0.8 mm in the left/right, 0.8 mm in the front/back, and 1.3 mm in the cranial/caudal direction. The corresponding control-group values were 1.1 mm, 1.3 mm, and 1.6 mm. CPD and controls differed significantly for the left/right movement of the rami (p = 0.04) but not for the other directions or rotations (p > 0.05). Conclusions: The results demonstrate that both methods are accurate, and postoperative results matched the virtually planned position precisely. It can be assumed that the described CPDs are beneficial when a condylar position different from the preoperative is desired.

Bone adhesives have significant potential for improving surgical procedures and can enhance and simplify them. Recently, phosphoserine-modified mineral-organic resorbable bone adhesives have shown particular promise. Among them, MgO/MgP-based cement exhibit high adhesive strength but suffer from water instability. This study introduces mineral-organic hard tissue adhesives based on organophosphates and magnesium phosphate with hydrolytic stability to enable cell testing. Amorphised magnesium phosphates enhanced reactivity, eliminating MgO additives. Alongside the established organophosphate phosphoserine (OPLS), sodium phytate was investigated as an alternative. We performed comprehensive mechanical and material characterizations, complemented by in vitro cytocompatibility assessments using osteoblastic MG-63 cells and osteoclastic RAW 264.7 cells differentiated with RANKL. Sodium phytate demonstrated strong adhesive properties, with an initial shear strength of 4.35 ± 0.86 MPa, retaining 1.3 ± 0.27 MPa after 7 days. However, it showed lower cytocompatibility with MG-63 cells than with OPLS. The OPLS/MgP combination exhibited both favorable cytocompatibility and strong adhesive performance, achieving an initial shear strength of 3.87 ± 0.53 MPa and maintaining 2.19 ± 0.69 MPa after 7 days. These findings underscore the potential of organophosphate-magnesium compound cement as viable candidates for mineral-organic hard tissue adhesives in surgical applications, combining excellent adhesive properties with favorable cytocompatibility.

Objectives: This study investigated novel mineral-organic cements based on magnesium and organophosphates, originally developed as resorbable bone adhesives. The aim was to evaluate this new class of materials in a dental context, focusing on their suitability as temporary restorative materials in endodontic treatments. Materials and methods: Two thermally treated trimagnesium phosphate hydrates (Mg₃(PO₄)₂ ∙ xH₂O and Mg₃(PO₄)₂ ∙ 22H₂O (cattiite)) were each combined with two organophosphates (phosphoserine (OPLS) and sodium phytate (Na-IP6)), resulting in four adhesive formulations. These were compared with a commonly used material for temporary restorations (Cavit™) and a reference adhesive (TTCP + OPLS) regarding mechanical strength, sealing ability (methylene blue penetration) on bovine teeth, and structural integrity. Results: Shear bond strength to dental hard tissues was significantly higher for the new cements compared to Cavit™, particularly for the OPLS + TMP ∙ xH₂O formulation (4.35 ± 0.71 MPa vs. 0.29 ± 0.16 MPa; initially on dentin). pH and temperature during setting remained within clinical limits. TMP ∙ xH₂O + OPLS also showed the favorable sealing behavior, while Cavit™ performed similarly. Porosimetry, SEM and micro-CT supported the favorable profile of this formulation. Conclusion: The combination of 400 °C sintered TMP ∙ xH₂O and OPLS proved most suitable in terms of handling, stability, and sealing. This system are promising candidates for temporary restorations, particularly in non-retentive cavities. Clinical relevance: The tested cements may serve as novel resorbable, adhesive alternatives for temporary restorations. Future applications could include pulp capping or perforation repair. Graphical

Bone defects resulting from trauma, diseases, or surgical procedures pose significant challenges in the field of oral and maxillofacial surgery. The development of effective bone substitute materials that promote bone healing and regeneration is crucial for successful clinical outcomes. Calcium phosphate cements (CPCs) have emerged as promising candidates for bone replacement due to their biocompatibility, bioactivity, and ability to integrate with host tissues. However, there is a continuous demand for further improvements in the mechanical properties, biodegradability, and bioactivity of these materials. Dual setting of cements is one way to improve the performance of CPCs. Therefore, silicate matrices can be incorporated in these cements. Silicate-based materials have shown great potential in various biomedical applications, including tissue engineering and drug delivery systems. In the context of bone regeneration, silicate matrices offer unique advantages such as improved mechanical stability, controlled release of bioactive ions, and enhanced cellular responses. Comprehensive assessments of both the material properties and biological responses of our samples were conducted. Cytocompatibility was assessed through in vitro testing using osteoblastic (MG-63) and osteoclastic (RAW 264.7) cell lines. Cell activity on the surfaces was quantified, and scanning electron microscopy (SEM) was employed to capture images of the RAW cells. In our study, incorporation of tetraethyl orthosilicate (TEOS) in dual-curing cements significantly enhanced physical properties, attributed to increased crosslinking density and reduced pore size. Higher alkoxysilyl group concentration improved biocompatibility by facilitating greater crosslinking. Additionally, our findings suggest citrate’s potential as an alternative retarder due to its positive interaction with the silicate matrix, offering insights for future dental material research. This paper aims to provide an overview of the importance of silicate matrices as modifiers for calcium phosphate cements, focusing on their impact on the mechanical properties, setting behaviour, and biocompatibility of the resulting composites.

Background/Objectives: Biomineral adhesive bone adhesives composed of phosphoserine combined with magnesium oxides or phosphates exhibit exceptional adhesive properties. This study evaluates two experimental mineral–organic cementitious adhesives in a clinical test setup, investigating their potential for fracture reduction and simultaneous defect filling. Methods: The two experimental adhesives (Groups B and C) and a standard hydroxyapatite cement (Group A, reference) underwent compressive strength testing, shear strength testing, and screw pullout tests as part of a first biomechanical characterization. Furthermore, all materials were tested in a porcine tibial split depression fracture model, where they served both for fracture reduction and for filling the metaphyseal bone defect, supplementary to plate osteosynthesis. Fracture stability was assessed under cyclic loading in a materials testing machine. Results: The OPLS (O-phospho-L-serine) containing adhesive (Group B) demonstrated the highest compressive strength as well as the highest shear strength. All three materials showed comparable maximum pullout forces. Both experimental adhesives (Groups B and C) exhibited higher pullout stiffness compared to the standard cement (Group A). In the fracture model, no significant differences in displacement under cyclic loading were observed between groups. Conclusions: The biomineral adhesive bone adhesives (Groups B and C) demonstrated biomechanical advantages in axial compression, adhesive (shear) strength, and screw fixation compared to the standard hydroxyapatite cement (Group A). Furthermore, they achieved comparable stabilization of metaphyseal fractures under clinically relevant dynamic loading conditions.