The aim of this study was to evaluate the clinical performance of glass fiber-reinforced composite-based resin-bonded fixed partial dentures (GFRC-RBFPDs) as periodontal splints for periodontal support-reduced anterior partially edentulous dentition and for replacing lost teeth. Materials and Methods: A total of 39 subjects were enrolled who required fixed restorations for lost mandibular anterior teeth where the adjacent teeth offered severely reduced periodontal support. GFRC-RBFPDs were cemented to replace the lost teeth and to stabilize the adjacent teeth. The survival rates were recorded, and the periodontal condition (bone height, bleeding index, and probing depth) was evaluated at 1, 2, 3, and 4 years after the restorations. The results were statistically analyzed with single-factor variance analysis and chi-square tests (α = .05). Results: The complete survival rate was 89.7%, and the functional survival rate was 92.3% at the fourth year. The main reason for failure was fracture of the connector of the GFRC-RBFPDs. In 21.7% of adjacent teeth, the bone height decreased; in the other 78.3%, it increased from 1 year after the restoration to the end of the observation period and the heights were statistically different from the initial values. The periodontal condition of the adjacent teeth was improved after the restoration. Conclusions: This 4-year clinical evaluation indicated that GFRC-RBFPDs may be useful as fixed prostheses to replace one to three lost anterior teeth with damaged periodontal support in adjacent teeth.

Injectable bone substitutes and techniques have been developed for use in minimally invasive procedures for bone augmentation. Objective: To develop a novel injectable thermo-sensitive alginate hydrogel (TSAH) as a scaffold to induce bone regeneration, using a minimally invasive tunnelling technique.Material and Methods : An injectable TSAH was prepared from a copolymer solution of 8.0 wt% Poly(N-isopropylacrylamide) (PNIPAAm) and 8.0 wt% AAlg-g-PNIPAAm. In vitro properties of the material, such as its microstructure and the sustained release of recombinant human bone morphogenetic protein-2 (rhBMP-2), were investigated. Then, with the subperiosteal tunnelling technique, this material, carrying rhBMP-2, was injected under the labial periosteum of the maxillary anterior alveolar ridge in a rabbit model. New bone formation was evaluated by means of X-ray, micro-computed tomography (micro-CT), fluorescence labelling, histological study, and immunohistochemistry study.Results : The material exhibited good injectability and thermo-irreversible properties. SEM showed an interconnected porous microstructure of the TSAH. The result of ALP activity indicated sustained delivery of BMP-2 from the TSAH from days 3 to 15. In a rabbit model, both TSAH and TSAH/rhBMP-2 induced alveolar ridge augmentation. The percentage of mineralised tissue in the TSAH/rhBMP-2 group (41.6±3.79%) was significantly higher than in the TSAH group (31.3±7.21%; p<0.05). The density of the regenerating tissue was higher in the TSAH/rhBMP-2 group than in the other groups (TSAH group, positive control, blank control; p<0.05).Conclusions : The TSAH provided convenient handling properties for clinical application. To some extent, TSAH could induce ridge augmentation and mineral deposition, which can be enhanced when combined with rhBMP-2 for a minimally invasive tunnelling injection.

In this study, an injectable and thermo-sensitive alginate/β-tricalcium phosphate hydrogel (TSAH/β-TCP) was prepared for aspirin release to a bone defect. Aspirin was dissolved into a mixture of poly(N-isopropylacrylamide) (PNIPAAm), an aminated alginate-g-PNIPAAm co-polymer, and β-TCP powders. Scanning electron microscopy showed that TSAH/β-TCP had an interconnected porous microstructure with a porosity of 86.78%. The cross-linked hydrogel released approximately 40% of the aspirin in the first 3 days and then slowly released the remainder. At a low concentration (≤100 μg/mL), aspirin did not promote cell proliferation, but enhanced the alkaline phosphatase activity, and osteocalcin (OCN) and collagen I expression of human bone marrow-derived mesenchymal stem cells. The TSAH/β-TCP/aspirin hydrogel was injected into the periosteum of the rat cranial bone, and its in vivo bone-forming ability was evaluated at 12 weeks. A bone morphogenetic protein 2 (BMP-2)-loaded TSAH/β-TCP hydrogel was injected as a control. Micro-computed tomography showed that the percentage of mineralized tissue in the TSAH/β-TCP/BMP-2 and TSAH/β-TCP/aspirin groups were similar and significantly higher than that in the TSAH/β-TCP group. Immunohistochemical staining showed considerable expression of OCN, especially in the TSAH/β-TCP/BMP-2 and TSAH/β-TCP/aspirin groups. These results suggest that the injectable TSAH/β-TCP/aspirin hydrogel has great potential for bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1739-1751, 2018.