title: An in vitro study to compare the effect of two etching techniques on the tensile bond strength of resin cement bonded to base metal alloy and enamel.
abstract: Resin-bonded retainers are being preferred for anterior restorations. To increase the retentive strength of the metal fixed to the tooth, the retainer surface has to be etched. Different etching techniques are described in the literature with different researchers expressing the superiority of one technique over the other. This study was conducted to compare electro chemical and chemical etching techniques and the mode of bond failure. Twenty human maxillary premolars with the crown portion separated from root were embedded in resin block such that mesial or distal portion of it was exposed on the top of the block. 4 × 5 mm area was marked on the tooth, and wax pattern was prepared to cover the exact area, with the opposite end having a hook like structure which was later attached to universal testing machine. Wiron99 Ni-Cr alloy was used for casting. Once the casting and etching procedures were finished, wax patterns were invested, casted and half the samples were etched chemically using Aqua-regia and the other half samples were etched electrochemically. The castings were cleaned and cemented to tooth structure using Rely-X ARC (3 M ESPE, USA) resin cement. Specimens were fixed to universal testing machine and de-bonded. The load required to de-bond and mode of de-bonding was noted. Results were subjected to five different statistical tests, each test specific to the variable being tested. The mean failure load was calculated as 5.95 kg for electrochemically etched samples and that of chemically etched samples was calculated as 11.15 kg. The standard deviation of the force required to debond the specimens (Kgf) was calculated and found to be 0.65 for electrochemically etched samples and 1.11 for chemically etched samples. The following conclusions have been drawn from the study. 1. Chemical etching of the samples created better retentive surfaces than electrochemical etching. 2. The results of mode of de-bonding show that in case of chemical etching maximum debonding occurred at resin-enamel interface and in electrochemical type it occurred at resin-metal interface.
authors.affiliation: Department of Prosthodontics, Sree Mookambika Institute of Dental Sciences, Kulasekharam, Tamilnadu India.
authors.forename: Arunachalam
authors.initials: A
authors.lastname: Sudheer
authors.affiliation: Department of Prosthodontics, Bapuji Dental College and Hospital, Davangere, Karnataka India.
authors.forename: Gautam
authors.initials: G
authors.lastname: Shetty
keywords: Chemical etching; Current density; Electro chemical etching