Evaluation of new bioceramic endodontic sealers: An in vitro study.

BACKGROUND: The biophysical properties of root canal sealers (RCSs) positively affect the success of endodontic treatment. It is important to ensure an impermeable apical seal after the thorough eradication of the infection. Since bioceramic sealers release bioactive and concomitantly biocompatible products after setting, chemical bonding to dentin and favorable healing is achieved. OBJECTIVES: This study evaluated the chemical composition and elemental distribution of 4 RCSs (1 resinbased and 3 bioceramic-based) by using energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM) and elemental mapping after root canal obturation, both coronally and apically. MATERIAL AND METHODS: Forty extracted single-rooted teeth were shaped, cleaned and randomly divided into 4 groups according to the type of sealer used for obturation. After the sealer set, the teeth were sectioned horizontally to obtain coronal and apical standardized sections. The sections were qualitatively and quantitatively assessed in terms of chemical composition of the tested sealers, using SEM images and elemental mapping as well as the EDX analysis. RESULTS: All of the calcium silicate sealers showed significantly higher peaks of calcium at the periphery of the root canals, contacting dentinal moisture, and high peaks of zirconium, while tungsten was significantly high in AH Plus™. TotalFill® BC™ and BioRoot™ RCS showed higher calcium, oxygen and silicon content coronally than apically, while phosphorus was only detected more apically, which was different for EndoSeal® MTA. All sealers revealed small amounts of different heavy metals, not described by their manufacturers, and a uniform particle distribution with almost regular surfaces. CONCLUSIONS: All of the tested sealers except AH Plus revealed high calcium/phosphorus ratio peaks, suggesting regenerative potential in vivo, with acceptable purity and surface texture, and supporting their biocompatibility, with chemical bonding to root dentin.

Fracture toughness of chairside CAD/CAM materials - Alternative loading approach for compact tension test.

OBJECTIVE: This in-vitro study determined plane-strain fracture toughness (KIC) of five different chairside CAD/CAM materials used for crown fabrication, following alternative innovative loading approach of compact tension test specimens. METHODS: Rectangular-shaped specimens were cut from CAD/CAM blocks (n=10): Vita Mark II (Vident) (VMII); Lava-Ultimate (3M/ESPE) (LU); Vita Enamic (Vident) (VE); IPS e.max CAD (Ivoclar Vivadent); crystallized and un-crystallized (E-max and E-max-U, respectively); and Celtra Duo (Dentsply) fired and unfired (CD and CD-U, respectively). Specimens were notched with thin diamond disk prior to testing. Instead of applying tensile loading through drilled holes, a specially-made wedge-shaped steel loading-bar was used to apply compressive load at the notch area in Instron universal testing machine. The bar engaged the top » of the notch before compressive load was applied at a cross-head speed of 0.5mm/min. Fracture load was recorded and KIC calculated. Data was statistically-analyzed with one-way ANOVA at 95% confidence level and Tukey's tests. RESULTS: Means and SDs of KIC in MPam(1/2) for VMII, LU, VE, E-max, E-max-U, CD and CD-U were: 0.73 (0.13), 0.85 (0.21), 1.02 (0.19), 1.88 (0.62), 0.81 (0.25), 2.65 (0.32) and 1.01 (0.15), respectively. ANOVA revealed significant difference among the groups (p<0.001). CD and E-max had significantly highest mean KIC values. SIGNIFICANCE: Mean KIC values of the tested materials varied considerably, however, none of them reached mean KIC of dentin (3.08MPam(1/2)) previously reported. For E-max and CD, specimens firing significantly increased mean KIC. The modified test arrangement was found to be easy to follow and simplified specimen preparation process.

Hydrazones of 2-aryl-quinoline-4-carboxylic acid hydrazides: synthesis and preliminary evaluation as antimicrobial agents.

A new series of 2-arylquinoline-4-carboxylic acid hydrazide-hydrazones was synthesized using an appropriate synthetic route. All the target compounds were evaluated for their in vitro antimicrobial activity against Staphylococcus aureus as an example for Gram-positive bacteria, Escherichia coli as an example for Gram-negative bacteria, and Candida albicans as a representative of fungi. The minimum inhibitory concentration (MIC) was determined for test compounds as well as for reference standards. Among the compounds tested, compounds having nitro substituents at the arylidene moiety showed the most potent antifungal as well as antibacterial activities against E. coli. Compound 23 displayed an antifungal activity comparable to that of nystatin. However, none of the compounds demonstrated any antibacterial activity against S. aureus. Hydrophobicity of the target compounds correlated weakly with their antibacterial and antifungal activities. The most potent compounds namely, 7, 18, 19, 22, and 23 were assessed for hemolytic toxicity and found to be non-hemolytic up to a concentration of 100mug/mL. In addition, the most potent compound (23) was evaluated for in vitro cytotoxic activity against various cancer cell lines. This compound was found to display no cytotoxic activity but rather it induces the proliferation rate of Hep-G2 cells.