Photopolymerization of Light Curing Adhesives Used with Metal Orthodontic Brackets and Matrices

: Kilponen L, Uusitalo E, Tolvanen M, Varrela J, Vallittu PK

Publisher: AMER SCIENTIFIC PUBLISHERS

: 2016

: Journal of Biomaterials and Tissue Engineering

: JOURNAL OF BIOMATERIALS AND TISSUE ENGINEERING

: J BIOMATER TISS ENG

: 6

: 8

: 659

: 664

: 6

: 2157-9083

DOI: https://doi.org/10.1166/jbt.2016.1483

Objective: To measure the degree of conversion (DC%) of light-curing orthodontic adhesives under both orthodontic brackets and metal matrices. In addition, the transmission of curing light through dentin slices of different thicknesses was evaluated. Methods: Two light-curing dimethacrylate adhesives (Transbond (TM) XT and Enlight) were each tested in 11 groups (n = 5/group): a control group (without a bracket), under a bracket, and under four different sized pieces of dental matrices shielding the resin from light curing. Additional groups contained a continuous E-glass-fiber weave in the adhesive interface. The adhesives were light-cured for 40 s and the DC% was measured with FT-IR. The transmission of curing light was measured through slices of dentin (0.5, 1.0, 2.0, 3.0 and 4.0 mm). Results: Both bracket and metal matrices prevented the DC% of the adhesive from reaching the DC% of the control. Transbond (TM) showed lower DC% than Enlight. The DC% was higher with a piece of glass-fiber weave (p < 0.05). Dentin slices influenced transmission of curing light significantly with a decrease from 1845 mW/cm(2) to zero through dentine slice of 4.0 mm. Conclusions: The photopolymerization of light curing adhesives was influenced by the light shielding effect of both the metal brackets and the matrices. Dentine slices attenuated the curing light.