Degree of Conversion, Depth of Cure, and Color Stability of Experimental Dental Composite Formulated with Camphorquinone and Phenanthrenequinone Photoinitiators

<jats:title>Abstract</jats:title><jats:sec><jats:title>Purpose</jats:title><jats:p>This study evaluated the applicability of 9,10‐phenanthrenequinone (<jats:styled-content style="fixed-case">PQ</jats:styled-content>) in experimental dental composites.</jats:p></jats:sec><jats:sec><jats:title>Materials</jats:title><jats:p>Camphorquinone (<jats:styled-content style="fixed-case">CQ</jats:styled-content>), <jats:styled-content style="fixed-case">PQ</jats:styled-content>, ethyl 4‐<jats:styled-content style="fixed-case">N</jats:styled-content>,<jats:styled-content style="fixed-case">N</jats:styled-content>‐dimethylaminobenzoate (<jats:styled-content style="fixed-case">EDMAB</jats:styled-content>) and diphenyliodonium salt (<jats:styled-content style="fixed-case">DPI</jats:styled-content>) were employed. A mixture of 2,2‐bis(4‐[2‐hydroxy‐3‐methacryloxypropoxy]phenyl)‐propane/triethylene glycol dimethacrylate (60:40%) and silanated glass filler at 60% were used. A two‐peak‐based light‐emitting diode (<jats:styled-content style="fixed-case">LED</jats:styled-content>) was used.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>The photoinitiator absorption and the light emission spectra were determined by a Ultraviolet–visible spectroscopy and a spectroradiometer, respectively. Relative photon absorption (<jats:styled-content style="fixed-case">RPabs</jats:styled-content>) was calculated. Fourier‐transformed infrared spectroscopy analysis was used to determine the degree of conversion (<jats:styled-content style="fixed-case">DC</jats:styled-content>). The optical properties were determined with a spectrophotometer. Depth of cure was assessed from adapted International Organization for Standardization (ISO) 4049. Results were analyzed with descriptive analysis, analysis of variance, and <jats:styled-content style="fixed-case">T</jats:styled-content>ukey's test (α = 5%).</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p><jats:styled-content style="fixed-case">PQ</jats:styled-content> showed higher <jats:styled-content style="fixed-case">RPabs</jats:styled-content> than <jats:styled-content style="fixed-case">CQ</jats:styled-content>. Regarding the <jats:styled-content style="fixed-case">DC</jats:styled-content>, <jats:styled-content style="fixed-case">CQ</jats:styled-content> + <jats:styled-content style="fixed-case">EDMAB</jats:styled-content> (control), <jats:styled-content style="fixed-case">CQ</jats:styled-content> + <jats:styled-content style="fixed-case">EDMAB</jats:styled-content> + <jats:styled-content style="fixed-case">DPI</jats:styled-content>, <jats:styled-content style="fixed-case">PQ</jats:styled-content> + <jats:styled-content style="fixed-case">DPI</jats:styled-content>, and <jats:styled-content style="fixed-case">PQ</jats:styled-content> + <jats:styled-content style="fixed-case">EDMAB</jats:styled-content> + <jats:styled-content style="fixed-case">DPI</jats:styled-content> produced statistically similar results. Groups formulated with <jats:styled-content style="fixed-case">CQ</jats:styled-content> presented higher depth of cure. Only the group formulated with <jats:styled-content style="fixed-case">CQ</jats:styled-content> + <jats:styled-content style="fixed-case">EDMAB</jats:styled-content> presented satisfactory color stability (Δ<jats:styled-content style="fixed-case">E</jats:styled-content> < 3.3).</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p><jats:styled-content style="fixed-case">PQ</jats:styled-content> presented higher <jats:styled-content style="fixed-case">RPabs</jats:styled-content> than <jats:styled-content style="fixed-case">CQ</jats:styled-content> and it was able to produce <jats:styled-content style="fixed-case">DC</jats:styled-content> similar to <jats:styled-content style="fixed-case">CQ</jats:styled-content> + <jats:styled-content style="fixed-case">EDMAB</jats:styled-content>, when used with <jats:styled-content style="fixed-case">DPI</jats:styled-content>. However, groups formulated with <jats:styled-content style="fixed-case">PQ</jats:styled-content> produced lower depth of cure, greater yellowing, and less color stability than the traditional combination <jats:styled-content style="fixed-case">CQ</jats:styled-content> and amine.</jats:p></jats:sec><jats:sec><jats:title>Clinical Significance</jats:title><jats:p>Although research with novel photoinitiator systems should be encouraged, the traditional camphorquinone and amine pair remains as a reliable combination for the formulation of dental composites.</jats:p></jats:sec>