Degree of Conversion and Cell Viability of Iodonium salt/MDP-containing Adhesives

Objectives: To characterize through degree of conversion (DC) and cell viability analyses adhesives containing the photoinitiators systems camphorquinone/amine and camphorquinone/amine/DPHIF salt associated with MDP, light activated with a conventional LED device or a broad spectrum one. This study evaluated three factors: photoinitiator system (CQ/amine or CQ/amine/DPHIF), concentration of MDP (0%, 3% or 12%) and curing unit device (conventional LED or broad-spectrum LED). Two response variables were studied: DC and biocompatibility.
Methods: Experimental adhesives were prepared containing camphorquinone/amine or camphorquinone/amine/DPHIF as photoinitiators and three different concentrations of MDP (0%, 3% or 12%). The DC was evaluated by FTIR-ATR. The cell viability was evaluated by testing the cell viability through MTT and crystal violet tests. Experimental adhesives were light activated with two devices: a broad-spectrum LED device and a conventional LED one. The data were analyzed by Anova and Tukey's HSD (α = 0.05).
Results: Significant differences were found between photoinitiator systems (p = 0.007) and MDP concentration (p <0.001). The light-curing device was not significant (p = 0.33). The double photoinitiator system presented a lower DC in relation to the triple system. The DC increased with the addition of MDP. The only significant interactions occurred between photoinitiator and percentage of MDP (p = 0.0007) and between photoinitiator and light-curing device (p = 0.0015). No cytotoxic effects were observed for all adhesives evaluated.
Conclusions: The photoinitiator and the addition of MDP influenced the degree of conversion without affecting the cell viability.