ABSTRACT
The aim of this study was to examine the compatibility of Ce-TZP/Al2O3 nanocomposite (CTA) frameworks and veneering porcelains using the Schwickerath crack initiation test and clarify the effects on debonding/crack initiation strength (DIS) of both surface pretreatment (include heat treatment) of the frameworks, type of veneering porcelain varying the coefficient of thermal expansion (CTE), and surface roughness of the frameworks. The surfaces of Ce-TZP/Al2O3 plates were mechanically treated and followed by post-heat treatment. The liner and body porcelains were built up and fired according to the manufacturer's instructions. Surface analyses of the fractured plates showed compatibility with liner porcelains. Since no statistically difference in the DIS was found amongst the different surface treatments, post-heat treatments don't be mandatory. Whereas, since differences in DIS were found when different porcelains with different CTE were used, we concluded the matching of CTE of the porcelain with that of Ce-TZP/Al2O3 was important for successful all-ceramic restorations using Ce-TZP/Al2O3 frameworks.
Subject(s)
Aluminum Oxide/therapeutic use , Cerium/therapeutic use , Composite Resins/therapeutic use , Dental Porcelain , Dental Veneers , Nanocomposites , Zirconium/therapeutic use , X-Ray DiffractionABSTRACT
A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramic bonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed in this study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconia plate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconia specimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) were carried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89 MPa). SCT revealed that the bonding strengths of test groups using resin cement were significantly higher than those of Control. Notably, the bonding strengths of RE and ML were above 25 MPa even after 10,000 times of thermal cycling -adequately meeting the ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in that a CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement.
Subject(s)
Dental Bonding , Dental Materials/chemistry , Dental Porcelain/chemistry , Dental Prosthesis Design , Dental Restoration, Permanent/methods , Resin Cements/chemistry , Zirconium/chemistry , Aluminum Oxide/chemistry , Aluminum Silicates/chemistry , Apatites/chemistry , Ceramics/chemistry , Computer-Aided Design , Dental Cements/chemistry , Dental Stress Analysis/instrumentation , Feasibility Studies , Hardness , Humans , Materials Testing , Methacrylates/chemistry , Shear Strength , Silanes/chemistry , Stress, Mechanical , Surface Properties , Temperature , Time Factors , Yttrium/chemistryABSTRACT
In the course of our search for natural antipsychotic agents, we isolated five new cyclic tetrapeptides from the fermentation broth of Nonomuraea sp. TA-0426. These compounds turned out to be analogues of WSS2220, which had been produced by the same actinomycete and showed strong inhibitory activity against GlyT1. Four of the present peptides exhibit more potent GlyT1 inhibitory activities than WSS2220.
Subject(s)
Actinomyces/metabolism , Antipsychotic Agents/pharmacology , Glycine Plasma Membrane Transport Proteins/antagonists & inhibitors , Glycine Plasma Membrane Transport Proteins/chemistry , Glycine/chemistry , Peptides/chemistry , Antipsychotic Agents/chemical synthesis , Cell Line, Tumor , Dose-Response Relationship, Drug , Humans , Inhibitory Concentration 50 , Isoleucine/chemistry , Magnetic Resonance Spectroscopy , Methylation , Models, Chemical , Structure-Activity Relationship , Time FactorsABSTRACT
To improve the metabolic stability of a 16-membered macrolide, 2-methylated derivatives of desmycosin were synthesized. Among these derivatives, 2beta-methyldesmycosin retained antibacterial activity and showed improved stability in rat serum compared to desmycosin.
