objective:   the aim of this study was to evaluate the bond strength between metal brackets and non-glazed ceramic with three different surface treatment methods. materials and methods: forty-two non-glazed ceramic disks were assigned into three groups. group i and ii specimens were etched with 9.5% hydrofluoric acid. subsequently in group i, silane and adhesive were applied and in group ii, bo...

background: laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. the purpose of this study was to compare the shear bond strength (sbs) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (er:yag) laser. materials and methods: in this expe...

background. acid etching prior to orthodontic bracket bonding may result in enamel wear or cracks following bracket removal. the manufacturer of fuji ortho lc glass-ionomer (gi) claims that it can bond brackets to wet unetched enamel. this study aimed to compare the bracket bond strength to etched and unetched enamel under dry and wet conditions. methods. in this in vitro study, 60 intact premo...

In this research, the protonation constant value of tannic acid was determined at 25 °C and different ionic strengths (0.1 to 0.7 mol/dm3 NaCl) using potentiometric titration technique. The dependence of protonation constant on ionic strength was modeled and discussed by a Debye-Hückel type equation. Then, based on the obtained data from experiments, the minimizing Sum o...

     In this study, the effect of the secondary structure of the protein on the acid strength of three structures of random (R), alpha helix (α) and beta sheet (b) were investigated theoretically. These structures are related to the cationic amino acids of histidine and lysine in the polypeptide chain of eight-glycine residue. Computational methods at the HF, B3LYP, X3LYP and M05-2X levels in t...

the major foible of dental ceramics is their brittle nature. therefore, the producers of these materials have focused on the “strength” issue. a method of increasing strength is ion exchange on porcelain surface which leads to formation of a compressive crust that opposing forces should overcome before developing a crack. in current study, ion exchange in two types of porcelain, ceramco ii whic...

Background and Aim: Debonding is the most commonly encountered failure in teeth restored with fiber posts that mainly occurs at the weakest interface (dentin-cement interface). Thus, reinforcement of this interface is mandatory. The aim of this study was to evaluate the effect of different root dentin surface treatments after post space preparation on bond strength of fiber posts cemented with ...