title: Effects of thermocycling on the bond strength of a resin-modified glass ionomer cement: an in vitro comparative study.
abstract: This study investigated the effects of thermally induced stresses (thermocycling) on the shear bond strength of resin-modified, chemically cured, glass ionomer cement for use as an orthodontic bonding agent. A conventional no-mix composite resin was also used as a control. Mesh-based metal orthodontic brackets were bonded to extracted human premolars using either the resin-modified glass ionomer cement or the no-mix composite resin. Specimens were stored either in water at 37 degrees C for 24 hours for baseline data or thermocycled between 5 degrees C and 55 degrees C for 200 and 20,000 cycles before testing the in vitro shear bond strengths. Thermocycling reduced shear bond strengths for all specimens. The resin-modified glass ionomer cement showed a 11.1% decrease after 200 thermocycles and 26.5% decrease after 20,000 thermocycles, whereas the no-mix adhesive resin showed only 5.7% and 17.9% reductions, respectively. Analysis of variance showed statistically significant differences between the mean shear bond strengths of the groups at the P < .001 level of significance. For the resin-modified glass ionomer cement groups, the predominant bond failure site was at the bracket-adhesive interface. The results of this study suggest strongly that resin-modified glass ionomer cements offer a viable alternative to conventional no-mix composite resins, with satisfactory in vitro shear bond strength even after 20,000 thermocycles.
authors.affiliation: Department of Orthodontics, Ondokuz Mayis University, Samsun, Turkey. sarici@omu.edu.tr
authors.forename: Selim
authors.initials: S
authors.lastname: Arici
authors.forename: Nursel
authors.initials: N
authors.lastname: Arici
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid / Q000648:ultrastructure; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry; D001840:Dental Bonding; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D013995:Time; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D005899:Glass Ionomer Cements; D019279:Resin Cements; D014867:Water