Illuminant metameric effects on interbrand and intrabrand color differences of direct composite resins.

STATEMENT OF PROBLEM: Information on the illuminant metameric effects on the intrabrand and interbrand differences in color of direct composite resins is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different illuminations on the color differences of the same or different brands of composite resins. MATERIAL AND METHODS: Sixty-four disks were prepared from 8 different direct dental composite resins of A3 shade, and, after polymerization and hydration for 48 hours, their color coordinates were measured in the Commission Internationale de I'Eclairage (CIE) L∗a∗b∗ color space with a portable colorimeter on a black and white background under D65 (daylight), F2 (cool white fluorescence), and A (incandescence) illuminations. Translucency parameters (TP) and fluorescence intensities (FI) of the brands were also measured to assist in the interpretation of brand behavior under the illuminations. The Kruskal-Wallis and Friedman nonparametric tests with post hoc multiple comparisons tests were applied to analyze the data for differences within and between brands under all illuminations (α=.05), while regression analysis was used to estimate the relationship between D65 and F2 or A illumination data. RESULTS: Statistical analysis showed significant differences among brands (P<.05) for all color coordinates under all illuminations, with a strong linear relationship between them (R2=0.72-0.97). Intrabrand differences were significantly different across brands (P<.05) and ranged from 0.06 to 3.1 across illuminations in ΔE∗ab units (0.05 to 2.4 in ΔΕ00 units). Interbrand differences were also significantly different (P<.05), with a range of 0.15 to 8.7 ΔE∗ab units or 0.14 to 5.7 ΔΕ00 units. CONCLUSIONS: Primary color coordinates of composite resins were affected by A or F2 illumination and were strongly associated with D65 values. Redder or yellower composite resins were affected more under A or F2 illumination. Intrabrand differences, although small, may contribute to clinical mismatches under A or F2 illuminations. Clinicians should be aware that certain brand pairs may present acceptable differences under D65 illumination but could become unacceptable under A or F2 illumination.

Fluorescence intensities of composite resins on photo images.

Recording fluorescence using flash photography, may help reduce time of capture and apply effectively in clinical practice. To test methods for visualizing composite resins fluorescence by direct digital photography. Sixty-four specimen discs (1.5 × 10 mm) were prepared from 8 different composite resin brands. Their CIELAB color coordinates (L*, a*, b*) and fluorescence were measured using a portable colorimeter and a fluorescence spectrophotometer. The mean of three measurements was recorded and then specimens were photographed by a DSLR camera with two different filters (365 nm and 405 nm) mounted on a commercial macro flash. RGB values of all specimens on the photographs were measured by using Photoshop software and converted to CIELab. Data were then analyzed using Kruskal-Wallis and Dunn's multiple comparisons tests. Correlation and regression analyses were also used to relate fluorescence and color parameters on the photographs at α = 0.05. Fluorescence and color data indicated significant differences among the materials (p < 0.05). L* a* and b* color coordinates from both photographs were highly correlated to fluorescence intensities found by the reference method (r365 - 0.95, r405 - 0.94), while regression analysis indicated a strong linear relationship (R2365 - 0.88, R2405 - 0.89). The study showed that filtered flash photography either by the use of a 365 nm or a 405 nm band pass filter can directly visualize fluorescence of composite resin materials and differences in fluorescence between them.

The effect of disposable infection control sleeves on the total energy delivered by dental LCUs.

AIM: This study compared the effect of seven different disposable cross-infection control sleeves on the total energy delivered (J/cm2) by four different dental light-curing units (LCUs). METHODS: Four LCUs and seven disposable sleeves (six proprietary brands and a general-purpose cellophane wrap) were used. Anterior and posterior tooth position was included as a third factor. Total energy delivered was measured for each LCU without a sleeve (control) and with each sleeve and for each tooth position. Curing time was 10 seconds, as recommended by the LCU manufacturers. Measurements were taken 10 times for each sleeve/LCU/tooth position and means (SD) calculated. Data were analysed using three-way analysis of variance (ANOVA). The null hypothesis was that none of the sleeves would, at a 0.1% level, significantly affect the total energy delivered. RESULTS: All sleeves significantly reduced the total energy delivered (P < 0.001). Cellophane wrap (cling film) had the smallest effect on total energy. Total energy delivered was most strongly influenced by tooth position and LCU model. CONCLUSIONS: Sleeves significantly reduce the total energy delivered compared to unsleeved LCUs, but to a degree that may not be clinically important. Cling film reduced total energy delivered to a significantly lesser extent than did proprietary bands of sleeve. In order to determine adequacy of delivered total energy, sleeved LCUs should be tested prior to clinical use.