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“Photo-‐Fenton and Convencional In-‐of4ice Dental Bleaching”P.E. CAPEL CARDOSO, A. MUENCH and H.B. PINHEIRO - Universidade de São Paulo, São Paulo, Brazil FDI - 2011 - #348
Dental professionals and patients everywhere request a more efficient dental whitening treatment, ideally faster. For more than a century, in-office dental whitening treatment has been performed in much the same way, using hydrogen peroxides in high concentrations that vary between 30 to 38%. Light and heat may be used to accelerate the HP chemical reaction (Fig. 1). All very similar to the procedure described by Fisher in 1910. The redox potential of the HP (H2O2) is 1.76 eV (Fig. 3), whereas a well known advanced oxidation process (AOP) widely used to oxidize contaminants and waste water treatment, the Photo-Fenton reaction (Fig. 2) based on a combination of HP, an iron catalyst and light/energy, has a redox potential of 2.83 eV (Fig. 3).
There is a system for dental whitening treatment in the market based on the Photo-Fenton reaction, which uses a HP at 25%. The lower HP concentration is also desired. A clinical trial can indicate the whitening result of this new system when compared to a gold standard convencional in-office whitening treatment. The results obtained can assist dentists when choosing a system for their patients.
This clinical trial evaluated the results of two in-office whitening treatment methods, one based on the Photo-Fenton reaction and the other a convencional in-office system, verifying shade change (∆E) and color stability.
Results
ZAP OPX
0
1
2
3
4
5
6
7
8
9
7 days after bleaching 14 days after bleaching 30 days after bleaching
∆E
8.4 (+-2.3)
5.5 (+-1.2)
8.2 (+-1.7)
5.5 (+-1.5)
8.5 (+-3.0)
5.9 (+-1.5)
Homogeneity and homoscedasticity tests were applied to the data obtained which indicated that two way ANOVA and Tukey test were the best tests to treat the results. Statistical analysis comparing the results obtained for shade change over time (pre and post whitening treatment after 7, 14 and 30 days) demonstrated that ZAP Group presented a superior whitening result when compared to group OPX (Table 2 and Fig. 11). Shade change stability was observed for both groups.
Experimental groups
7 days after bleaching
14 days after bleaching
30 days after bleaching
ZAP (n=20) 8.4 (+-2.3) Aa 8.2 (+-1.7) Ca 8.5 (+-3.0) Ea
OPX (n=20) 5.5 (+-1.2) Bb 5.5 (+-1.5) Db 5.9 (+-1.5) Fb
Table 2. Description of experimental groups
Means with different lowercase letters in the same row are statistically different (p<0.05).Means with different capital letters in the same column are statistically different (p<0.05).
This clinical trial indicates that even though a lower concentration HP (25%) is employed by the whitening system that uses the Photo-Fenton reaction, it presented a superior performance when compared to the convencional in-office whitening system using a higher concentration HP (38%), which indicates the efficacy of the Photo-Fenton process. Both systems presented color stability during the 30 days evaluation period.
1. Fisher. The bleaching of discolored teeth with hidrogen peroxide. Dental Cosmos, 1910. 53: p. 246-7.2. Haywood, V.B. and H.O. Haymann. Nightguard vital bleaching. Quintessence Int, 1989. 20(3): p. 173-76. 3. Kim-Pusateri S, Brewer JD, Davis EL, Wee AG. Reliability and accuracy of four dental shade-matching devices. J Prosthet Dent. 2009 Mar;101(3):193-9.4. Oppenländer, T. Photochemical Purification of Water and Air, Advanced Oxidation Processes (AOP): Principles, Reaction Mechanisms, Reactor Concepts. Wiley-VCH. 353p. 2003.5. Parsons, S. Advanced Oxidation Process for Water and Wastewater Treatment. IWA Publishing Alliance House. 347p. 2005.
Results Representative FEG-SEM micrographs:
Material and Methods
Experimental groups Description
ZAP (n=20) 25% HP + ferrous gluconate (Discus Dental) + Zoom AP Light (Discus Dental) –1 treatment session*
OPX (n=20) 38% HP-Opalescence Xtra Boost (Ultradent) –1 treatment session*
Table 1. Description of experimental groups
* Each treatment session consisted of three applications of whitening gel for 15 minutes each one, according to manufacturers’ instruction.
∆E = (∆L*2+∆a*2+∆b*2)1/2
Figure 8
Figure 7Figure 6
Figure 9Figure 10
After approval by the University Ethics Committee, 40 volunteers were selected, signed an informed consent and were instructed on the procedures. The volunteers were randomly divided into 2 groups (Table 1) of 20 patients each (n=20). Group 1: ZAP; Group 2: OPX. The whitening treatment for both groups was performed with 3 consecutive 15-minute applications. The shade of superior incisives and canines was assessed using a digital Easyshade spectrophotometer (Fig. 4 and 5) immediately before and post the whitening treatment at 7, 14 and 30 days.
The use of Vita-Easyshade Spectrophotometer assured objective measurements. This device measures the color based on a tri-dimensional system called CIELab (Fig. 6 and 7), defined by the International Commission on Illumination. This system supplies numerical values that inserted into a formula (Fig. 8) provides the color or shade variation, also known as ∆E. This is an accurate and efficient method to measure the change in tooth color; it eliminates the subjective influence of the human eye. Currently, this is one of the most widely used tools for color evaluation in clinical trials of teeth whitening.
To ensure that measurements were taken at the same spot on each tooth, a custom clear EVA tray was used. Holes in the tray on the labial surface of incisors and canines (Fig. 9) were made with a specially designed bur, 6 mm in diameter, corresponding to the size of the tip of the optical spectrophotometer reader (Fig. 10).
Figure 4
VITA Easyshade® Advance
Número do modelo: DEASYAS
Data de publicação: 05.11
Manual de Instruções
Figure 5
Oppenländer, 2003
Figure 3
Fe2+ + H2O2 Fe 3+ + *OH + OH- (1)
Figure 2
Fe (OH)3++ hv Fe 2+ + *OH (2)Figure 1
2H2O2 2H2O + O2
Figure 11
www.arq.usfc.br www.erx50.com
Objective
Clinical Relevance
Conclusion
Results
References
Please find below some of the more relevant sources used for this clinical trial. The complete bibliography can be provided by the authors upon request.
