Effect of different surface treatments on shear bond strength of ceramic brackets to old composite
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RESEARCH ARTICLE
Open Access
Effect of different surface treatments on shear bond strength of ceramic brackets to old composite Homa Farhadifard1, Loghman Rezaei-Soufi2, Maryam Farhadian3 and Parisa Shokouhi4*
Abstract Background: At present, the demand for orthodontic treatment is on the rise. On the other hand, evidence shows that the bond strength of composite resins to old composite restorations is often unreliable. Therefore, the aim of this in vitro study was to assess the effect of different surface treatments on shear bond strength (SBS) of ceramic brackets to old composite restorations. Methods: In this in vitro experimental study, 60 nano-hybrid composite discs were fabricated. For aging, the discs were incubated in deionized water at 37 °C for 1 month. Next, they underwent 4 different surface treatments namely acid etching with 37% phosphoric acid, sandblasting, grinding, and Er,Cr:YSGG laser irradiation. Ceramic brackets were then bonded to the discs and underwent SBS testing. Results: The maximum mean SBS value was obtained in the grinding group (9.16 ± 2.49 MPa), followed by the sandblasting (8.13 ± 2.58 MPa) and laser (6.57 ± 1.45 MPa) groups. The minimum mean SBS value was noted in the control group (5.07 ± 2.14 MPa). Conclusion: All groups except for the control group showed clinically acceptable SBS. Therefore, grinding, sandblasting, and Er,Cr:YSGG laser are suggested as effective surface treatments for bonding of ceramic orthodontic brackets to aged composite. Keywords: Shear strength, Er,Cr:YSGG laser, Sandblasting, Grinding, In vitro
Background The increasing demand of adults for orthodontic treatment has been associated with some problems. Since many adult patients requiring orthodontic treatment have several composite, amalgam, and porcelain restorations, orthodontists face more challenges in bracket bonding to restored teeth. This problem is more evident in patients with composite restorations especially in the labial surface of their maxillary incisors or buccal surface of their posterior teeth [1]. * Correspondence: [email protected] 4 School of Dentistry, Hamadan University of Medical Sciences, 6517838677 Shahid Fahmideh Street, Hamadan City, Hamadan, Iran Full list of author information is available at the end of the article
Evidence shows that the bond strength of composite resin to old composite restorations is often unreliable [2]. As composite restorations age, the number of available vinyls for cross-polymerization to the new composite layer decreases; therefore, chemical bonding between the old composite and the new composite resin is challenging [3]. It has been proven that the etching process with orthophosphoric acid cannot alter the surface topography of composite resin, and only cleans the superficial layer [4, 5] Therefore, increasing the bond strength between the new and old composite usually requires additional surface roughening of the old composite to improve mechanical interlocking and subsequent coating of the surface with the bonding agent to improve surfa
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