Chemical etching solutions for creating micromechanical retention in resin-bonded retainers

Effects of a metal etchant and two primers on resin bonding durability to titanium

The purpose of this study was to investigate the efficacy of an etchant in titanium bonding. The aqueous etchant consisted of 0, 5, or 10 wt% ammonium hydrogen fluoride (AHF) in combination with 0, 0.03, 0.3, or 3 wt% cupric chloride (CC). The two primers used were a phosphate-methacrylate primer and a thiophosphate-methacrylate primer, and two self-curing resins (Super-Bond C&B and MT) were employed as luting agents. Disk specimens were cast with a commercially pure titanium. The surface was air-abraded with 50 microm alumina, etched for 10 s, rinsed with water, and then air-dried. The primer was applied to the bonding area (5 mm in diameter), and an acrylic rod was bonded to the specimen with the luting agent. Shear bond strengths were evaluated after 24 h of water storage and following 10,000 thermocycles (4 degrees C and 60 degrees C). The post-thermocycling bond strength was significantly increased with each of the two primers compared with the unprimed controls. The etchant containing 5 wt% AHF and 0.3 wt% CC further increased their durability, and microscopic observation revealed that innumerable submicron crystals were created on the etched specimen. The present results suggest that the chemical etching improved the resin bonding durability to titanium in combination with the primer used.

Analysis of depth of the microporosity in a nickel-chromium system alloy - effects of electrolytic, chemical and sandblasting etching

The present study was designed to analyse the average depth of the microporosity of a nickel-chromium (Ni-Cr) system alloy (Verabond II). The metal surface was subject to one of the following surface treatment: (i) Electrolytic etching in nitric acid 0.5 N at a current density of 250 mA cm(-2); (ii) chemical etching with CG-Etch etchant; and (iii) Sandblasting with alumina particles 50 microm. Half of the samples were polished before the surface treatments. The depth of porosity was measured through photomicrographs (500x) with a profilometer, and the data were statistically analysed using an analysis of variance (anova) followed by Tukey's test. The conclusions were (i) Differents surface treatment of the Ni-Cr system alloy lead to different depths of microporosity; (ii) The greatest depth of porosity was observed in non-polished alloy; (iii) The greatest and identical depth of microporosity was observed following electrolytic etching and chemical etching; (iv) The least and identical depth of microporosity was observed with chemical etching and sandblasting with alumina particles 50 microm, and (v) Chemical etching showed an intermediary depth.