A Systematic Review of Bone Marrow Stromal Cells and Periosteum-Derived Cells for Bone Regeneration.

Bone marrow stromal cells (BMSCs) and periosteum-derived cells (PDCs) represent promising skeletal stem cell sources to treat critical-size bone defects. However, the large number of preclinical tests with a variety of in vivo data complicates the selection of cells for further clinical translation. This systematic review aims to analyze the in vivo bone-forming efficacy of BMSCs- and PDCs-based approaches in all published preclinical experiments until November 2020. For this purpose, four databases (PubMed, Embase, Cochrane Central Register of Controlled Trial, and Web of Science) were searched for eligible literature, which yielded a total of 94 full-text articles for systematic review. This review generated an evidence-based list of BMSC- or PDC-based approaches, which have been evaluated for bone formation in different animal models. Among them, 74 studies were included for pairwise and network meta-analysis. The results revealed that both PDC and BMSC had beneficial bone-forming efficacy compared to bare scaffold. In addition, BMSC- and PDC-based approaches had no significant difference regarding in vivo bone-forming efficacy. However, BMSC-based approach had a higher probability to be ranked better than PDC-based approach. Furthermore, the review discusses (i) the possible risk of bias of the in vivo evaluation of cell-based approaches, (ii) the difficulty in replication of such experiments due to frequent poor reporting of the methods and results, and (iii) the clinical relevance of the currently utilized BMSC- and PDC-based approaches. Systematic review registration: The study was prospectively registered in PROSPERO, Registration No. CRD42021270922.

Effect of the implant-supported provisional restoration on the accuracy of digital peri-implant mucosa replication-A clinical study.

OBJECTIVE: This study aimed to quantitatively evaluate the effect of implant-supported provisional restorations (ISPRs) on the accuracy of the intraoral scanned peri-implant soft-tissue profile in the esthetic area. MATERIALS AND METHODS: Sixteen patients with a single ISPR in the maxillary central incisor's region were recruited for this study. Three impression methods were sequentially used in each patient: (1) an intraoral scanning (IOS) with the ISPR, (2) a conventional impression using the ISPR as impression coping, and (3) a routine IOS without the ISPR. The stereolithography files of the three impression methods obtained from the same patient were superimposed, and the conventional impression method was used as the reference model. Two-dimensional (2D) and three-dimensional (3D) analyses were performed to measure the peri-implant soft-tissue deviation between the reference models and IOS from the groups with or without the ISPR, respectively. Data were presented as the means ± standard deviations. Two-way analyses of variance with post hoc Sidak's multiple comparisons and paired t-tests were performed for 2D and 3D analyses, respectively. The significance level was set at p < .05. RESULTS: The peri-implant mucosa without the ISPR immediately collapsed (<20 s), particularly on the palatine side of the labial mucosa and labial side of the palatine mucosa. Consequently, the IOS without the ISPR led to 414.7 ± 116.0 µm of overall dimensional deformation in the cuff-like submucosal region, which was significantly larger (p < .0001) than that in the IOS with the ISPR (230.6 ± 85.5 µm). CONCLUSION: Implant-supported provisional restorations are important for accurate replication of the intraorally scanned peri-implant soft-tissue profile.

Circulator-free on-chip bidirectional four-wave mixing.

On-chip bidirectional four-wave mixing (FWM), which may meet the rapidly increasing demands on integration level and system versatility, has never been implemented for the lack of competent on-chip optical circulators that are indispensable for separating the bidirectional channels. In this scenario, we first propose and demonstrate a circulator-free scheme that fully utilizes the inherent clockwise and counter-clockwise transmission natural of an add-drop microring resonator to implement on-chip bidirectional FWM. It should be noted that the proposed scheme additionally provides a universal solution for multichannel nonlinear operations and the related applications, with the advantages of compact structure and low crosstalk. The implementation for multimode channels is investigated for demonstration, as the mode division multiplexing technique is of particular interest in integrated optoelectronics and the resonance-enhanced nonlinear structure with superior dimension compared to straight waveguides has never been implemented for a multimode case. The experimental results exhibit that the FWM efficiencies of the two-mode channels are -26.78 and -28.69 dB, respectively, and the crosstalk is lower than -35 dB.

Silicon Integrated Interferometric Optical Gyroscope.

Miniaturized and low-cost optical gyroscopes are urgently required for emerging applications in consumer electronics market. In this paper, we proposed a theoretical analysis and preliminary experiment results for integrated interferometric optical gyroscope based on the silicon-on-insulator (SOI) platform for the first time. The gyroscope is based on the Sagnac effect and composed of coiled multimode waveguides to reduce propagation loss and the footprint. The sensitivity of the sensing part is fully investigated in terms of waveguide loss, gyroscope footprint, crossing numbers for coiled waveguides, as well as the waveguide cross section. The experimental results show that gyroscope sensitivity is 51.3 deg/s with a footprint of 600 µm × 700 µm.