Bond strength of three chairside crown reline materials to milled polymethyl methacrylate resin.

STATEMENT OF PROBLEM: Information on the bond strength of milled polymethyl methacrylate interim restorations when relined with chairside reline materials is lacking. PURPOSE: The purpose of this in vitro study was to measure the shear bond strength of various combinations of 3 different chairside reline materials bonded to milled polymethyl methacrylate blocks with 3 different types of surface treatments. MATERIALS AND METHODS: Uniform blocks (10×10×22 mm) were milled from tooth-colored polymethyl methacrylate disks (Vivid PMMA; Pearson Dental Supply Co). The surface treatments tested were airborne-particle abrasion with 50-µm particle size aluminosilicate, application of acrylic resin monomer (Jet Liquid; Lang Dental Manufacturing Co) for 180 seconds, and airborne-particle abrasion with monomer application. The control groups were blocks with no surface treatment. The chairside reline materials tested were Jet acrylic resin (Jet Powder; Lang Dental Manufacturing Co), bis-acryl resin (Integrity; Dentsply Sirona), and flowable composite resin (Reveal; Bisco). All materials were applied through a Ø1.5×3-mm bonding ring. Ten specimens for each of the 12 groups were tested in a universal testing machine. Load was applied at a crosshead speed of 1 mm/min. Fracture surfaces were then analyzed for cohesive versus adhesive or mixed failure. Data were analyzed using 2-way ANOVA and Tukey-Kramer post hoc analysis (α=.05). RESULTS: The mean shear bond strength values ranged from 1.77 ±0.79 MPa to 28.49 ±5.75 MPa. ANOVA revealed that reline material (P<.05), surface treatment (P<.05), and their interactions (P<.05) significantly affected the shear bond strength among the experimental groups. The strongest combination was Jet acrylic resin applied on specimens treated with airborne-particle abrasion and monomer. All 3 failure modalities (adhesive, cohesive, and mixed modes) were observed. CONCLUSIONS: Of the materials tested, the most reliable material to bond to milled polymethyl methacrylate was Jet acrylic resin, and the bond strength values were increased substantially when the milled polymethyl methacrylate surface was airborne-particle abraded and monomer was applied.

[Molecular mechanism of wendan tang in prevention of lipid metabolism disorder in adult rats].

OBJECTIVE: To elucidate the molecular mechanism of Wendan Tang in prevention of lipid metabolism disorder in adult rats. METHOD: On the basis of hyperlipidemia rat models, triglycerides (TG), total cholesterol (TC) in serum, activities of lipase (LA), lipoprotein lipase (LPL), hepatic lipase (HL) in liver, parts of hemogram and hepatic LDLR mRNA levels were investigated 21 days after the feeding of atherogenic diet. RESULT: Wendan Tang significantly reduced the serum TG, TC and increased the activity of LPL and LA, but caused no chang in HL. The result of RT-PCR test showed that high fat and high cholesterol feeding could significantly induce the reduction of LDLR mRNA levels, while Wendan Tang could increase hepatic LDLR density. CONCLUSION: Wendan Tang can prevent disorder of lipid metabolism by regulating TC, TG, LDL-c through upregaulation of LDLR transcription level and improving antioxidant ability.