tahereh sadat jafarzadeh kashi

The purpose of this in vitro study was to investigate drug release kinetics and cytotoxicity of a novel drug delivery system for treatment of periodontitis.

This in vitro study addresses the fabrication of a polycaprolactone/ alginic acid‑based polymeric film loaded with metronidazole, as a basic drug in the treatment of periodontal diseases. Films were prepared by solvent casting technique. Four formulations with different percentages of drug by weight (3%, 5%, 9%, and 13%) were prepared. Drug release kinetics were investigated using ultraviolet–visible spectroscopy during (one week). Data were analyzed using repeated measures ANOVA. Cytotoxicity of drug‑loaded system extracts was evaluated by 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay using L929 cells after 24‑h incubation. The results were evaluated according to ISO standard 10993‑5 and assessed using ANOVA and Tukey’s tests at a significance level of P < 0.05.

All polymeric films showed a burst drug release followed by a gradual release. Drug release data were fitted well with the first‑order kinetic model in all drug‑containing formulations indicating that drug release is a fraction of remaining drug in the matrix. Drug release is mainly driven by diffusion of medium into the composite matrix. 3%wt metronidazole‑containing formulation exhibited the best MTT result.

The findings of this study supported the synthesis of drug‑loaded periodontal films with 3% metronidazole due to better biological properties along with the ability of acceptable drug release to eradicate anaerobic periodontal bacteria.

Evidence on the protecting effect of laser on bleached enamel is scarce and controversial. Therefore, we aimed to test for the first time whether different wavelengths of diode laser (810 and 980 nm) can prevent enamel surface corrosion. We also tested for the first time whether such therapeutic effects of laser are limited to specific “laser‑activated” bleaching gels or both conventional and laser‑activated gels. In this qualitative experimental study, ten intact human teeth were randomly assigned to five Groups. They were sectioned into twenty buccal/lingual pieces. The groups were: (1) laser‑activated gel + 810 nm laser, (2) laser‑activated gel + 980 nm laser, (3) conventional gel + 810 nm laser, (4) conventional gel + 980 nm laser, (5) conventional gel only, and (6) laser‑activated gel ‑ no irradiation. Buccal sections in each group were subjected to bleaching (according to the stated protocols), and later subjected to field‑emission scanning electron microscopy (SEM) and X‑ray diffraction (XRD). The lingual pieces were used as “before‑treatment” negative controls for XRD. XRD showed an increase in the mineral phase and crystallinity of the enamel in all bleaching groups. This was stronger in the laser‑irradiated groups with conventional bleaching agent. SEM showed a complete etched surface in the positive control groups (i.e., bleached using conventional agent). However, all four laser groups had almost intact surfaces. This study showed the positive effect of diode laser irradiation at 810 nm or 980 nm wavelengths on the prevention of bleaching damage, irrespective of the activation mechanism of the bleaching gel in use.

Poly(methyl methacrylate) (PMMA) is the most common material used to fabricate complete and partial dentures. Despite its desirable properties, it cannot fulfill all mechanical requirements of prosthesis. Flexural fatigue due to repeated masticatory and high-impact forces caused by dropping are the main causes of denture fractures. In the past, different reinforcing agents such as rubbers, macro fibers, and fillers have been employed to improve the mechanical properties of denture base resins. Development of Nano dentistry has introduced new approaches for reinforcement of dental materials. Interest in nanostructure materials is driven by their high surface area to volume ratio, which enhances interfacial interaction and specific new biological, physical, and chemical properties. Researchers to reinforce PMMA resins have used Nanoparticles (Nps) which were comprised of silver, Titania (TiO2), zirconia (ZrO2), alumina, and ceramic. Although different reports describe the use of nanofiber and nanotubes in dental composites, few studies have evaluated the reinforcement potential of nanofiber and nanotubes in PMMA denture base resins. The current article aims to review the different attempts to enhance the mechanical properties of denture base materials. We also focus on recent advances and potential future developments for reinforcement of the PMMA acrylic resins.

The aim of this study was to evaluate the invitro and invivo performance of a 3 wt% of strontium additive hydroxyapatite calcium phosphate cements (CPC). The prepared calcium phosphate cement was characterized with XRD, FTIR, setting time, STA and in vitro and in vivo biological analyses. The MTT assay ALP activities as in vitro study and radiological and histological examinations as in vivo study between the three groups of 3 wt% Sr-HA/CPC, CPC and control were performed and compared. Data were analyzed using T-test and One-way ANOVA. XRD analysis demonstrated that by increasing the ratio of Powder/Liquid (P/L), the crystallinity of the prepared cement increased. The substitution of strontium instead of calcium in CPC could also alter the crystal structure, including some structural disorder. However, in the CPC with no strontium hydroxyapatite (Sr-HA), no significant increase in the crystallinity was observed. SEM observations revealed CPC with increasing P/L ratio, the formation of hydroxyapatite crystals arising from the interaction of solid and liquid phase of cement was decreased. Also, the addition of Sr within Ca site culminated in a dramatic increase in crystallinity of hydroxyapatite. In vitro biological properties ascertained that addition of 3 wt. % Sr-HA into CPC enhanced MTT assay and ALP activity, which could be due to the presence of strontium ions. The histological study showed that greater remodeling was seen at 4 weeks after implantation when the 3 wt% Sr-HA/CPC was used. The obtained results cleared that CPC can be a potential candidate as a carrier with strontium additives for bone remodeling and regeneration.

The aim of this study was to measure the degree of conversion (DC) of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer) with different light curing units (LED LCU and QTH LCU) in two depths.

Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Ceram X, Dentsply, Germany-M2 shade). Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit (Coltolux 75-Colten) and the other five specimens were cured by LED (Demi-Kerr). Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR (Bruker-tensor 27). The data were analyzed by 3-way ANOVA test.

There was significant difference between tested composite resins (P<0.001). The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001). The type of curing unit affected the polymerization of Ceram X resin composite.

This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.

Propolis has traditionally been used in curing infections and healing wounds and burns. Current researches have shown that propolis has antibacterial, antifungal and antiviral actions however, the pharmacological activity of propolis is highly variable depending on its geographic origin. There have been few studies on the effects of Iranian propolis on the oral microorganisms. In this in-vitro study, the antimicrobial activity of the ethanolic and water extracts of the Iranian propolis (10%, w/v) from north-east area of Tehran was evaluated. Susceptibility of the oral strains tested (Streptococcus mutans ATCC 35668; Streptococcus salivarius ATCC 9222; Staphylococcus aureus ATCC 25923; Enterococcus faecalis ATCC 9854 and Lactobacillus casei ATCC 39392) was evaluated using the agar diffusion method at a concentration of 20 mg/mL of propolis and the zones of growth inhibition were measured. Antibacterial activity was determined by using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) at different concentrations of propolis. The ethanolic extract showed bacteriostatic and bactericidal activity against all the strains, with MIC and MBC ranges of 250-500 µg/mL. The MIC concentration of the water extract was 500 µg/mL against S. mutans and E. faecalis. The water extract showed bactericidal activity only against S. mutans (20 mg/mL). These results indicate that the ethanolic extract is probably more useful in the control of oral biofilms and subsequent dental caries development. However, to determine the consequence of the ethanolic extract of Iranian propolis on the oral mucosa, in-vivo studies of its possible effects are needed.