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Due to economic, cultural, environmental, and social factors, the prevalence of maxillofacial bone disorders varies in different parts of the world. The present meta-analysis was conducted to assess the efficacy and safety of different type of stem cells-based scaffolds and their construction methods in maxillofacial bone disorders. We searched major indexing databases, including PubMed/Medline, ISI Web of Science, Scopus, Embase, and Cochrane Central without any language, study region, or type restrictions. A systematic search of articles published up to July 2021 was done. Of the 428 studies found through initial searches, 36 met the inclusion criteria. After applying the exclusion criteria, the main properties of 32 articles on 643 animals and 4 experimental studies on 52 patients (age range from 43 to 74 years) included in this meta-analysis. Our pooled analysis showed that stem cells-based scaffolds significantly improved the bone regeneration and formation in maxillofacial bone disorders (Prevalence: 0.54; 95% CI: 0.43, 0.64, P < 00001, I2 = 90 2). According to the results of these studies, in most studies, bone marrow-derived mesenchymal stem cells (BMSCs) have been used to regenerate bone, and these cells are still the gold standard in bone tissue engineering, a growth factor that is one of the three sides of the tissue engineering triangle. Bone morphogenetic proteins (BMP) especially BMP2 and platelet-rich plasma (PRP) are the most widely used growth factor and scaffold respectively. Platelet-rich plasma (PRP) is used as a scaffold and since it contains proteins, it also used as a growth factor and can be a stimulant of ossification. It seems that the future perspective of bone tissue engineering is to use the prototyping rapid method to build a composite and patient-specific scaffold from CT and MRI images, along with genetically modified stem cells.
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Background: The literature on the effect of bleaching on stainability and color stability of any composites is scarce and controversial. In the case of some composites and/or bleaching agents or staining solutions, there is no previous study. Therefore, this rather large study was conducted for the first time to examine simultaneously the effects of bleaching and 3 staining solutions on 3 composite types. Materials and Methods: This 3-phase experimental in vitro study was performed on 18 groups of 5 specimens each: 90 composite discs with 10 mm diameter and 1 mm thickness were fabricated from 3 resin composites (microhybrid, nanohybrid, and nanofilled). Forty-five discs underwent bleaching with 15% carbamide peroxide, and the remaining 45 were immersed in distilled water at room temperature. The color assessment was performed before and after this step, and Δa, Δb, and ΔL color parameters were calculated for each specimen. The specimens were then immersed in coffee, cola, and red grape juice for 2 weeks, and underwent colorimetry again. The simultaneous effects of bleaching and staining agents and composite types on ΔE (color changes) of composite specimens were analyzed using an independent-samples t-test, a Mann-Whitney U-test, and two-way and one-way analysis of variances followed by a Tukey and a Dunnett's T3 tests (α = 0.05). Results: Bleaching had no significant effect on color changes of microhybrid, nanohybrid, or nanofilled composites (P > 0.05). The stainability of composites did not increase after bleaching (P > 0.05). Regardless of the composite type and the presence of bleaching, coffee had the worst effect on color of composite specimens, while cola had the smallest staining effect (P < 0.05). Conclusion: Stainability of microhybrid/nanohybrid/nanofilled composites did not increase after bleaching with 15% carbamide peroxide. Coffee should be consumed with care, as far as composite coloring is a concern, regardless of the type of composite in use or its bleaching history. Cola was the weakest stainer. Coffee always caused perceptible staining (ΔE >3.7), regardless of the composite in use or its bleaching history. Red grape juice caused such perceptible colorations in most cases. Cola did not cause any perceptible discoloration in most cases.
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OBJECTIVE: This work investigates the graft polymerization of acrylic acid onto nanoclay platelets to be utilized as reinforcing fillers in an experimental dental adhesive. Physical and mechanical properties of the adhesive and its shear bond strength to dentin are studied. The effect of the modification on the stability of the nanoparticle dispersion in the dilute adhesive is also investigated. MATERIALS AND METHODS: Poly(acrylic acid) (PAA) was grafted onto the pristine Na-MMT nanoclay (Cloisite(®) Na(+)) through the free radical polymerization of acylic acid in an aqueous media. The resulting PAA-g-nanoclay was characterized using FTIR, TGA and X-ray diffraction (XRD). The modified nanoclays were added to an experimental dental adhesive in different concentrations and the morphology of the nanoclay layers in the photocured adhesive matrix was studied using TEM and XRD. Shear bond strength of the adhesives containing different filler contents was tested on the human premolar teeth. The stability of nanoclay dispersion in the dilute adhesive was also studied using a separation analyzer. The results were then statistically analyzed and compared. RESULTS: The results confirmed the grafting reaction and revealed a partially exfoliated structure for the PAA-g-nanoclay. Incorporation of 0.2 wt.% of the modified nanoclay into the experimental adhesive provided higher shear bond strength. The dispersion stability of the modified nanoparticles in the dilute adhesive was also enhanced more than 25 times. SIGNIFICANCE: Incorporation of the modified particles as reinforcing fillers into the adhesive resulted in higher mechanical properties. The nanofiller containing bonding agent also showed higher shear bond strength due to the probable interaction of the carboxylic acid functional groups on the surface of the modified particles with hydroxyapatite of dentin.