Restorative Dentistry & Endodontics

Research Article

Effect of immersion into solutions at various pH on the color stability of composite resins with different shades: Ji-Deok Moon, Eun-Mi Seon, Sung-Ae Son, Kyoung-Hwa Jung, Yong-Hoon Kwon, Jeong-Kil Park; Restor Dent Endod 2015;40(4):270-276. Published online August 28, 2015; DOI: https://doi.org/10.5395/rde.2015.40.4.270

Abstract PDF PubReader ePub: Objectives
This study examined the color changes of a resin composite with different shades upon exposure to water with different pH.
Materials and Methods
Nanohybrid resin composites (Filtek Z350XT, 3M ESPE) with four different shades (A2, A3, B1, and B2) were immersed in water with three different pH (pH 3, 6, and 9) for 14 day. The CIE L*a*b* color coordinates of the specimens were evaluated before and after immersion in the solutions. The color difference (ΔE*) and the translucency parameter (TP) were calculated using the color coordinates.
Results
ΔE* ranged from 0.33 to 1.58, and the values were affected significantly by the pH. The specimens immersed in a pH 6 solution showed the highest ΔE* values (0.87 - 1.58). The specimens with a B1 shade showed the lowest ΔE* change compared to the other shades. TP ranged from 7.01 to 9.46 depending on the pH and resin shade. The TP difference between before and after immersion in the pH solutions was less than 1.0.
Conclusions
The resulting change of color of the tested specimens did not appear to be clinically problematic because the color difference was < 1.6 in the acidic, neutral, and alkaline solutions regardless of the resin shade, i.e., the color change was imperceptible.

Original Article

The effect of different bonding systems on shear bond strength of repaired composite resin: Eun-Mi Seon, Hyeon-Cheol Kim, Bock Hur, Jeong-Kil Park; J Korean Acad Conserv Dent 2008;33(2):125-132. Published online March 31, 2008; DOI: https://doi.org/10.5395/JKACD.2008.33.2.125

Abstract PDF PubReader ePub: The purpose of this study is to compare the shear bond strength of repaired composite resin with different bonding agents and evaluate the effect of bonding agents on composite repair strength. Forty composite specimens (Z-250) were prepared and aged for 1week by thermocycling between 5 and 55℃ with a dwell time of 30s. After air abrasion with 50 µm aluminum oxide, following different bonding agents were applied (n = 10); SB group: Scotchbond multipurpose adhesive (3 step Total-Etch system); SE group: Clearfil SE bond (2 step Self-Etch system); XP group: XP bond (2 step Total-Etch system); XE group: XenoIII (1 step Self-Etch system). After bonding procedure was completed, new composite resin (Z-250) was applied to the mold and cured. For control group, 10 specimens were prepared. Seven days after repair, shear bond strength was measured. Data was statistically analyzed using one-way ANOVA and Tukey's test (p < 0.05). The means and standard deviations of shear bond strength (MPa ± S.D.) per group were as follows: SB group: 17.06; SE group: 19.10; XP group: 14.44; XE group: 13.57; Control Group: 19.40. No significant difference found in each group. Within the limit of this study, it was concluded that the different type of bonding system was not affect on the shear bond strength of repaired composite resin.

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