Antibacterial activity and biocompatibility of zein scaffolds containing silver-doped bioactive glass.

Composite 3D scaffolds combining natural polymers and bioceramics are promising candidates for bone tissue engineering (BTE). Zein, as a natural plant protein, offers several advantages, including biocompatibility, adequate strength properties, and low/no immunogenicity; however, it lacks bioactivity. Thus, composite zein: bioactive glass (BG) scaffolds are proposed as promising candidate for BTE applications, with silver-doping of bioactive glass providing an antibacterial effect against possible post-implantation infection. Therefore, the aim of this study was to investigate the in vitro antibacterial properties, biocompatibility, bioactivity and compressive strength of zein scaffolds containing silver-doped bioactive glass. BG nanoparticles, undoped and Ag-doped, were fabricated using the sol-gel method. 3D composite zein:BG scaffolds, containing 20 wt% BG, were prepared and their antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was assessed using the disc diffusion assay. Human osteoblast-like MG-63 cells were used to evaluate the in vitro biocompatibility of the prepared scaffold groups. In addition, the compressive strength of the scaffolds was determined using uniaxial compression strength testing and the scaffold interconnected porosity was measured using helium pycnometer. Disc diffusion assay showed that only zein scaffolds containing Ag-doped sol-gel BG are antibacterially positive against E. coli and S. aureus. Pure zein scaffolds and zein scaffolds containing sol-gel-derived BG showed no negative influence on the growth of MG-63 cells, as evident by the cells' ability to survive, proliferate, and function on these scaffolds. Moreover, incorporating sol-gel-derived BG into zein scaffolds at zein:BG of 80:20 ratio showed bioactive properties with adequate porosity without affecting the scaffolds' compressive strengths, which was similar to that of trabecular bone, suggesting that the new composites have potential for BTE applications in non-loaded bearing areas.

No clear evidence of superiority regarding pulp medicaments in primary molars.

DATA SOURCES: Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the Web of Science, OpenGrey, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry Platform. STUDY SELECTION: Two reviewers independently selected studies. Randomised controlled trials comparing different pulp interventions combining a pulp treatment technique and a medicament in primary teeth were considered. DATA EXTRACTION AND SYNTHESIS: Data abstraction and risk of bias assessment were carried out independently by two reviewers. The primary outcomes were clinical failure and radiological failure, as defined in trials, at six, 12 and 24 months. Pairwise meta-analysis using fixed-effect models was conducted with statistical heterogeneity being assessed using I2 coefficients. RESULTS: Forty-seven trials involving 3910 teeth were included. All were small single centre studies. The overall level of evidence was low with only one trial having a low risk of bias, 20 a high risk and 26 unclear risk of bias.The 47 trials examined 53 different comparisons: 25 for pulpotomy, 13 for pulpectomy, 13 for direct pulp capping and two comparisons between pulpotomy and pulpectomy.Regarding pulpotomy, 14 trials compared mineral trioxide aggregate (MTA) with formocresol (FC). MTA reduced both clinical and radiological failures at six, 12 and 24 months, although the difference was not statistically significant. MTA also showed favourable results for all secondary outcomes measured, although again, differences between MTA and FC were not statistically significant (with the exception of pathological root resorption at 24 months and dentine bridge formation at six months). MTA showed favourable results compared with calcium hydroxide (CH) (two trials) for all outcomes measured, but the differences were not statistically significant (with the exception of radiological failure at 12 months). When comparing MTA with ferric sulphate (FS) (three trials), MTA had statistically significantly fewer clinical, radiological and overall failures at 24 months. This difference was not shown at six or 12 months.FC was compared with CH in seven trials and with FS in seven trials. There was a statistically significant difference in favour of FC for clinical failure at six and 12 months, and radiological failure at six, 12 and 24 months. FC also showed favourable results for all secondary outcomes measured, although differences between FC and CH were not consistently statistically significant across time points. The comparisons between FC and FS showed no statistically significantly difference between the two medicaments for any outcome at any time point.For all other comparisons of medicaments used during pulpotomies, pulpectomies or direct pulp capping, the small numbers of studies and the inconsistency in results limits any interpretation. CONCLUSIONS: We found no evidence to identify one superior pulpotomy medicament and technique clearly. Two medicaments may be preferable: MTA or FS. The cost of MTA may preclude its clinical use and therefore FS could be used in such situations. Regarding other comparisons for pulpectomies or direct pulp capping, the small numbers of studies undertaking the same comparison limits any interpretation.