Effect of light-cure initiation time on polymerization efficiency and orthodontic bond strength with a resin-modified glass-ionomer. Orthod Craniofac Res 2012 May;15(2):124-34
Date
04/21/2012Pubmed ID
22515188DOI
10.1111/j.1601-6343.2011.01531.xScopus ID
2-s2.0-84860126154 (requires institutional sign-in at Scopus site) 6 CitationsAbstract
OBJECTIVES: The polymerization and acid-base reactions in resin-modified glass-ionomers (RMGI) are thought to compete with and inhibit one another. To examine the effect of visible light-cure (VLC) delay on the polymerization efficiency and orthodontic bond strength of a dual-cured RMGI.
SETTING AND SAMPLE POPULATION: The Orthodontics Graduate Program at Marquette University. An in vitro study utilizing 72 freshly extracted human bicuspid teeth.
MATERIALS AND METHODS: A RMGI light-cured immediately, 2.5, 5, or 10 min after mixing comprised the experimental groups. Isothermal and dynamic temperature scan differential scanning calorimetry (DSC) analysis of the RMGI was performed to determine extents of VLC polymerization and acid-base reaction exotherms. Human premolars (n = 18/group) were bonded with the RMGI. Shear bond strength and adhesive remnant index (ARI) scores were determined.
RESULTS: Differential scanning calorimetry results showed the 10-min-delay RMGI group experienced significantly (p < 0.05) lower VLC polymerization compared with the other groups. Acid-base reaction exotherms were undetected in all groups except the 10-min delay group. No significant differences (p > 0.05) were noted among the groups for mean shear bond strength. A chi-square test showed no significant difference (p = 0.428) in ARI scores between groups.
CONCLUSIONS: Delay in light-curing may reduce polymerization efficiency and alter the structure of the RMGI, but orthodontic shear bond strength does not appear to be compromised.
Author List
Thomas JT, Roberts HW, Diaz L, Bradley TG, Berzins DWAuthor
David Berzins BS,PhD Graduate Program Director for Dental Biomaterials in the General Dental Sciences/Dental Biomaterials department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
Acrylic ResinsAluminum Silicates
Analysis of Variance
Bicuspid
Calorimetry, Differential Scanning
Chi-Square Distribution
Dental Bonding
Dental Stress Analysis
Glass Ionomer Cements
Humans
Light-Curing of Dental Adhesives
Orthodontic Brackets
Polymerization
Shear Strength
Statistics, Nonparametric
Survival Analysis
Time Factors