Modification, 3D printing process and application of sodium alginate based hydrogels in soft tissue engineering: A review.

Sodium alginate (SA) is an inexpensive and biocompatible biomaterial with fast and gentle crosslinking that has been widely used in biological soft tissue repair/regeneration. Especially with the advent of 3D bioprinting technology, SA hydrogels have been applied more deeply in tissue engineering due to their excellent printability. Currently, the research on material modification, molding process and application of SA-based composite hydrogels has become a hot topic in tissue engineering, and a lot of fruitful results have been achieved. To better help readers have a comprehensive understanding of the development status of SA based hydrogels and their molding process in tissue engineering, in this review, we summarized SA modification methods, and provided a comparative analysis of the characteristics of various SA based hydrogels. Secondly, various molding methods of SA based hydrogels were introduced, the processing characteristics and the applications of different molding methods were analyzed and compared. Finally, the applications of SA based hydrogels in tissue engineering were reviewed, the challenges in their applications were also analyzed, and the future research directions were prospected. We believe this review is of great helpful for the researchers working in biomedical and tissue engineering.

Evolution from Bioinert to Bioresorbable: In Vivo Comparative Study of Additively Manufactured Metal Bone Scaffolds.

Additively manufactured scaffolds offer significant potential for treating bone defects, owing to their porous, customizable architecture and functionalization capabilities. Although various biomaterials have been investigated, metals - the most successful orthopedic material - have yet to yield satisfactory results. Conventional bio-inert metals, such as titanium (Ti) and its alloys, are widely used for fixation devices and reconstructive implants, but their non-bioresorbable nature and the mechanical property mismatch with human bones limit their application as porous scaffolds for bone regeneration. Advancements in additive manufacturing have facilitated the use of bioresorbable metals, including magnesium (Mg), zinc (Zn), and their alloys, as porous scaffolds via Laser Powder Bed Fusion (L-PBF) technology. This in vivo study presents a comprehensive, side-by-side comparative analysis of the interactions between bone regeneration and additively manufactured bio-inert/bioresorbable metal scaffolds, as well as their therapeutic outcomes. The research offers an in-depth understanding of the metal scaffold-assisted bone healing process, illustrating that Mg and Zn scaffolds contribute to the bone healing process in distinct ways, but ultimately deliver superior therapeutic outcomes compared to Ti scaffolds. These findings suggest that bioresorbable metal scaffolds hold considerable promise for the clinical treatment of bone defects in the near future.

[A survey on general knowledge and influencing factors of dental aesthetics among three universities students in Fuzhou city].

PURPOSE: To investigate the general knowledge of dental aesthetics among three universities students in Fuzhou city and the factors influencing their satisfaction with general dental appearance and the color of anterior teeth. METHODS: A cross-sectional questionnaire survey was conducted on 506 university students in Fuzhou city to identify their general knowledge of dental aesthetics. Logistic regression analysis was used to evaluate the factors influencing the study populations' satisfaction with dental appearance and the color of anterior teeth with SPSS 13.0 software package. RESULTS: The 506 respondents consisted of 220 males (43.5%) and 286 females (56.5%), with a mean age of 22.65 years (SD=1.95). 53.6% of these participants were not satisfied with their dental appearance, 57.2% were not satisfied with the color of their anterior teeth. The majority of the participants (66%) chose tooth bleaching as the most desired treatment to improve their dental appearance. Multivariate logistic regression analysis showed that respondents' dissatisfaction with dental appearance was significantly associated with gender (OR=1.94, 95% CI: 1.03-3.68), the opinion that their teeth were irregular (OR=2.70, 95% CI: 1.61-4.54) and unhappiness with anterior teeth color (OR=4.27; 95% CI: 2.47-7.33). The results also indicated that respondents' dissatisfaction with the color of anterior teeth was significantly associated with the professional learning experience of dentistry (OR=0.26, 95% CI: 1.61-4.54) and gender (OR=1.76, 95% CI: 1.05-2.96). CONCLUSIONS: Most of the respondents in this study are not satisfied with their dental appearance is the color of anterior teeth. Tooth bleaching is the treatment most desired by the participants. Tooth color is one of the most important factors determining whether respondents are satisfied with their dental appearance. Females pay a greater attention to dental aesthetics than males. Over one year professional learning experience of dentistry is the protective factor of respondents' satisfaction with the color of their anterior teeth.

Characterization and optimization of pH-responsive polymer nanoparticles for drug delivery to oral biofilms.

We previously reported on cationic, pH-responsive p(DMAEMA)-b-p(DMAEMA-co-BMA-co-PAA) block copolymer micelles with high affinity for dental and biofilm surfaces and efficient anti-bacterial drug release in response to acidic pH, characteristic of cariogenic (tooth-decay causing) biofilm microenvironments. Here, we show that micelle pH-responsive behaviors can be enhanced through alterations in corona:core molecular weight ratios (CCR). Although similarly stable at physiological pH, upon exposure to acidic pH, micelles with CCR of 4.1 were less stable than other CCR examined. Specifically, a ~1.5-fold increase in critical micelle concentration (CMC) and ~50% decrease in micelle diameters were observed for micelles with CCR of 4.1, compared to no changes in micelles with CCR of 0.8. While high CCR was shown to enhance pH-responsive drug release, it did not alter drug loading and dental surface binding of micelles. Diblocks were shown to encapsulate the antibacterial drug, farnesol, at maximal loading capacities of up to ~27 wt% and at >94% efficiencies, independent of CCR or core size, resulting in micelle diameter increases due to contributions of drug volume. Additionally, micelles with small diameters (~17 nm) show high binding capacity to hydroxyapatite and dental pellicle emulating surfaces based on Langmuir fit analyses of binding data. Finally, micelles with high CCR that have enhanced pH-responsive drug release and binding were shown to exhibit greater antibiofilm efficacy in situ. Overall, these data demonstrate how factors essential for nanoparticle carrier (NPC)-mediated drug deliverycan be enhanced via modification of diblock characteristics, resulting in greater antibiofilm efficacy in situ.