Restorative Dentistry & Endodontics

Clinical assessment of whitening efficacy and safety of in-office tooth whitening system containing 15% hydrogen peroxide with or without light activation: Young-Suk Noh, Young-Jee Rho, Yeon-Jee Yoo, Hyang-Ok Lee, Sang-Min Lim, Hyun-Jeong Kweon, Yeun Kim, Seong-Yeon Park, Hee-Young Yoon, Jung-Hyun Lee, Chan-Hee Lee, So-Ram Oh, Kee-Yeon Kum; J Korean Acad Conserv Dent 2011;36(4):306-312. Published online July 31, 2011; DOI: https://doi.org/10.5395/JKACD.2011.36.4.306

Abstract PDF PubReader ePub: Objectives
This clinical study evaluated the effect of light activation on the whitening efficacy and safety of in-office bleaching system containing 15% hydrogen peroxide gel.
Materials and Methods
Thirty-three volunteers were randomly treated with (n = 17, experimental group) or without light activation (n = 16, control group), using Zoom2 white gel (15% H₂O₂, Discus Dental) for a total treatment time of 45 min. Visual and instrumental color measurements were obtained using Vitapan Classical shade guide and Shadepilot (DeguDent) at screening test, after bleaching, and 1 month and 3 month after bleaching. Data were analyzed using t-test, repeated measure ANOVA, and chi-squared test.
Results
Zoom2 white gel produced significant shade changes in both experimental and control group when pre-treatment shade was compared with that after bleaching. However, shade difference between two groups was not statistically significant (p > 0.05). Tooth shade relapse was not detected at 3 months after bleaching. The incidence of transient tooth sensitivity was 39.4%, with being no differences between two groups.
Conclusions
The application of light activation with Zoom2 white gel system neither achieved additional whitening effects nor showed more detrimental influences.

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Effect of cross-sectional area of 6 nickel-titanium rotary instruments on the fatigue fracture under cyclic flexural stress: A fractographic analysis: Soo-Youn Hwang, So-Ram Oh, Yoon Lee, Sang-Min Lim, Kee-Yeon Kum; J Korean Acad Conserv Dent 2009;34(5):424-429. Published online September 30, 2009; DOI: https://doi.org/10.5395/JKACD.2009.34.5.424

Abstract PDF PubReader ePub: This study aimed to assess the influence of different cross-sectional area on the cyclic fatigue fracture of Ni-Ti rotary files using a fatigue tester incorporating cyclical axial movement. Six brands of Ni-Ti rotary files (ISO 30 size with .04 taper) of 10 each were tested: Alpha system (KOMET), HeroShaper (MicroMega), K3 (SybronEndo), Mtwo (VDW), NRT (Mani), and ProFile (Dentsply). A fatigue-tester (Denbotix) was designed to allow cyclic tension and compressive stress on the tip of the instrument. Each file was mounted on a torque controlled motor (Aseptico) using a 1:20 reduction contra-angle and was rotated at 300 rpm with a continuous, 6 mm axial oscillating motion inside an artificial steel canal. The canal had a 60° angle and a 5 mm radius of curvature. Instrument fracture was visually detected and the time until fracture was recorded by a digital stop watch. The data were analyzed statistically. Fractographic analysis of all fractured surfaces was performed to determine the fracture modes using a scanning electron microscope. Cross-sectional area at 3 mm from the tip of 3 unused Ni-Ti instruments for each group was calculated using Image-Pro Plus (Imagej 1.34n, NIH). Results showed that NRT and ProFile had significantly longer time to fracture compared to the other groups (p < .05). The cross-sectional area was not significantly associated with fatigue resistance. Fractographycally, all fractured surfaces demonstrated a combination of ductile and brittle fracture. In conclusion, there was no significant relationship between fatigue resistance and the cross-sectional area of Ni-Ti instruments under experimental conditions.

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Clinical study of shade improvement and safety of polymer-based pen type BlancTic Forte whitening agent containing 8.3% Carbamide peroxide: Jin-Kyung Lee, Sun-Hong Min, Sung-Tae Hong, So-Ram Oh, Shin-Hye Chung, Young-Hye Hwang, Sung-Yeop You, Kwang-Shik Bae, Seung-Ho Baek, Woo-Cheol Lee, Won-Jun Son, Kee-Yeon Kum; J Korean Acad Conserv Dent 2009;34(2):154-161. Published online March 31, 2009; DOI: https://doi.org/10.5395/JKACD.2009.34.2.154

This clinical study evaluated the whitening effect and safety of polymer based-pen type BlancTis Forte (NIBEC) containing 8.3% carbamide peroxide. Twenty volunteers used the BlancTis Forte whitening agent for 2 hours twice a day for 4 weeks. As a control, Whitening Effect Pen (LG) containing 3% hydrogen peroxide was used by 20 volunteers using the same protocol. The change in shade (ΔE^*, color difference) was measured using Shadepilot™ (DeguDent) before, during, and after bleaching (2 weeks, 4 weeks, and post-bleaching 4 weeks). A clinical examination for any side effects (tooth hypersensitivity or soft tissue complications) was also performed at each check-up. The following results were obtained.

1. Both the experimental and control groups displayed a noticeable change in shade (ΔE) of over 2. No significant differences were found between the two groups (p > 0.05), implying that the two agents have a similar whitening effect.

2. The whitening effect was mainly due to changes in a and b values rather than in L value (brightness). The experimental group showed a significantly higher change in b value, thus yellow shade, than the control (p < 0.05).

3. None of the participants complained of tooth hypersensitivity or soft tissue complications, confirming the safety of both whitening agents.

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