Translucency & Radiopacity of Five Resin Composites

Objective: Determine the translucency and radiopacity of five commercially availablecomposites: Aelite LS(AE), Filtek LS(FS), GC Kalore(KA), Empress DirectEnamel(EE), Empress Direct Dentin(ED)Experimental Methods: Experiment conducted according to ISO guideline 4049.Five composites(n=50), shade A2, were packed into an aluminum mold(10-mm diameter,1-mm thick) and light cured for 80 seconds(40 sec each side). The color of eachspecimen was measured according to the CIELAB color scale relative to the standardilluminant D65 against a white background and a black background using a reflectionspectrophotometer with a 8mm (MAV) diameter target mask. Using color data,translucency parameter and contrast ratio were calculated for each sample. Forradiopacity, five specimens(1 for each composite) were placed in random order with analuminum step wedge(20-mm x 50-mm, 10 0.5-mm steps) on an occlusal film andexposed at 70kV, 7mV, 0.339sec from a target-film distance of 360-mm. Afterimmediately being processed(10 radiographs), the radiographic optical densities of thespecimens and aluminum step wedge were read with a photographic transmissiondensitometer(aperture 1-mm). Aluminum equivalent was calculated using regressionanalysis(mean optical density vs. mean thickness aluminum step wedge). A visualanalysis by two independent examiners was also done and compared to the ISO 4049radiographic method. One-way ANOVA(p<0.05) and Tukey multiple comparisontests(p<0.05) were used for statistical analysis.Results: EE was the most translucent (22.089) and had the lowest contrast ratio(0.783)while AE was the least translucenct(11.808) and had the highest contrast ratio(0.908).For translucency all five composites were significantly different. For contrast ratio,except KA and FS, which were similar, all composites were significantly different. Therewas a very strong inverse correlation between translucency parameter and contrast ratio(-0.944). According to ISO guidelines 4049, a composite material is deemed radiopaque ifthe aluminum equivalent value of the material is greater than 1 mm. All five compositesmet this criteria with ED having the highest radiopacity(3.609 AlEq) and AE having thelowest radiopacity(1.263AlEq). All of the composites were significantly different exceptAE and FS, which were similar. Visually, ED was deemed the most visually radiopaqueby examiners and was significantly different than the other composites while EE/KA andFS/AE were not significantly different. FS and AE were least radiopaque visually. Therewas a strong correlation(0.938) between Al Radio Equiv and Visual Al Equiv whencomparing the materials as a group. There was much variation when correlating betweeneach material. There was a very weak to no correlation between radiopacity Al Equivand translucency(0.084) and contrast ratio(0.053).Conclusions: EE was the most translucent material. AE can be considered a veryopaque material but was the second most radiolucent material. ED had the highestradiopacity of the five composites but all five composites met ISO 4049 guidelines forradiopacity. Radiopacity and translucency were not correlated.