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Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study
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Journal of Dentistry journal homepage: www.intl.elsevierhealth.com/journals/jden
Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study Mahmoud K. AL-Omiria,b,* , Ra’ed S. Abul Hassanc, Bader K. AlZaread, Edward Lynche a
Faculty of Dentistry, University of Jordan, Amman, Jordan The City of London School of Dentistry, BPP University, UK Faculty of Allied Medical Sciences, The Royal University for Medical Sciences, Amman, Jordan d Faculty of Dentistry, AlJouf University, Sakaka, Saudi Arabia e Warwick Medical School, Coventry CV4 7AL, UK b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 5 November 2015 Received in revised form 21 January 2016 Accepted 24 January 2016 Available online xxx
Objectives: To evaluate the efficacy of tooth bleaching using ozone after hydrogen peroxide (H2O2) in comparison to the use of H2O2 alone. Methods: 70 extracted teeth were randomly distributed into two groups. Teeth surfaces in group 1 (n = 35) were treated using 38% H2O2 and then were exposed to ozone for 60 s and this ozonated peroxide mixture was left on the teeth for 20 min. Meanwhile, teeth in group 2 (n = 35) were treated with H2O2 38% for 20 min. The L* a* b* and Vita Classic shade values of teeth were evaluated in both groups at base line, after application of H2O2 and ozone in group 1, and after application of H2O2 and then again after another application of ozone in group 2. The statistically significant changes were set at P 0.05. Results: Baseline L* a* b* and Vita shade values were comparable between groups (P > 0.05). Teeth obtained lighter shades following bleaching with both H2O2 and ozone or with H2O2 alone (P 0.05). Further bleaching with ozone for teeth already bleached with H2O2 alone showed further improvement of the shades of teeth (P < 0.001). Teeth treated with H2O2 and ozone had more shade improvements than those only treated with H2O2 (P < 0.001). Also, L* values were increased while b* values were decreased (teeth obtained lighter shades) following bleaching in both groups (P 0.05). More changes were obtained when both ozone and H2O2 were used (P 0.05). Conclusions: Bleaching with 38% H2O2 and ozone resulted in teeth with lighter shades than bleaching with 38% H2O2 alone. ã 2016 Elsevier Ltd. All rights reserved.
Keywords: Ozone Hydrogen peroxide Bleaching HealOzone Tooth shade
1. Introduction Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. Ozone is the third most potent oxidant after fluorine and persulfate [1,2]. Also, it has analgesic properties, has a very potent antimicrobial activity (against bacteria, viruses, yeasts, and protozoa), and has the capacity to stimulate blood circulation and the immune response [1,2]. Such features justify the current interest in its application in medicine and dentistry; and therefore, ozone has been indicated for the treatment of more than 250 different pathologies [1–5]. Ozone therapy is used for many aspects in dentistry including biofilm purging, periodontal pocket disinfection, prevention and
* Corresponding author at: Faculty of Dentistry, The University of Jordan, Amman 11942, Jordan. E-mail address: [email protected] (M.K. AL-Omiri).
management of dental caries, treatment of exposed pulps, root canal treatment, tooth extraction, tooth sensitivity, TMJ treatment, exposed roots, pain control, infection control, acceleration of healing, tissue regeneration, control of halitosis, tooth surface remineralization, and bleaching [1–17]. Different ozone generating machines are used in dentistry including the healOzone and Ozicure machines [7–15]. Previous studies on ozone’s role in bleaching are scarce and reported conflicting results [18–21]. Manton et al. [18] found that 8% carbamide peroxide bleaching efficiency was not significantly improved by using ozone. However, Abd Elhamid and Mosallam [20] found that an ozonated gel had better bleaching effect and was associated with less surface roughness of bleached disc-shaped stained resin composite specimens when compared to 30% carbamide peroxide. Also, some researchers demonstrated that ozone could lighten tetracycline stained incisor teeth in rats [19]. Meanwhile, other researchers demonstrated that ozone could bleach teeth similar to
http://dx.doi.org/10.1016/j.jdent.2016.01.010 0300-5712/ ã 2016 Elsevier Ltd. All rights reserved.
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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The colorimeter was used in a custom made booth to standardize the ambient environment during measuring L* a* b* values of the sixteen Vita Classic shades. The colorimeter was fixed in the booth perpendicular to the measured teeth surfaces at a fixed distance of 7 cm away from the measured tooth surface. A cabinet (100 cm 90 cm 70 cm) that had a D65 light with 200– 300 foot candle intensity was used as the measuring booth following Ozcelik et al. [31] . The lighting unit of the measuring booth had three lamps mounted at different angles around the axis of the mounting unit to avoid creation of shadow and to obtain well distributed illumination at the measuring area. Moreover, lamps were turned on for 30 min before color measuring to produce stable and constant illumination following the recommendations of Gozalo-Diaz et al. [32]. The colorimeter was calibrated before each use by measuring a reference Vita Classic shade (B3) each time before tooth shade measurement under the same conditions. Then, the facial surfaces of teeth in group 1 (n = 35) were treated using 38% hydrogen peroxide professional whitening gel (BMS white 38%, BMS Dental, Italy) with ozone then immediately applied for 60 s into the peroxide on each tooth and this ozonated peroxide mixture was left on the teeth for 20 min. Next the teeth were gently rinsed with water for 5 s and gently air dried with a three in one syringe for 2 s. After that, the shade of teeth was recorded as above. The H2O2 gel was applied on teeth surfaces using mixing tips attached on a dual syringe that contains the whitening gel and provided by the manufacturer. The ozone was generated by the healozone1 X4 machine (healOzone1 X4, Curozone, Germany). The delivered ozone concentration was 2350 ppm at a flow rate of 615 cc per min [14]. The ozone was applied to teeth through special disposable silicone cups provided by the manufacturer. The used silicone cups ensured a complete seal and prevented ozone gas escape as the machine is designed to work only when the cup ensures a perfect seal, and thus this ensures the safety of the healOzone machine for human use [8]. All shade measurements were recorded in the region relating to what would have been the area of the tooth corresponding to where the center of the cup was located. Meanwhile, the facial surfaces of teeth in group 2 (n = 35) were treated using 38% H2O2 with air (instead of ozone) then immediately applied for 60 s into the peroxide and this airperoxide mixture was left on the teeth for 20 min in the way as described above. A specially designed healOzone was used which had a switch at the back of the device which was switched to deliver only air and no ozone. The shade of the teeth was then recorded by an assessor who was not aware of the delivery of ozone or just air. Then, the teeth in group 2 were further exposed to ozone treatment for 60 s and the shade was recorded again as above. Intraexaminer reliability was established with 10 duplicate shade readings on 10 teeth by the same investigator. Kappa was 0.92, indicating significant agreement as the measuring environment and criteria were standardized, clear and simple. Interexaminer reliability was also assessed by having another investigator record the same 10 shade readings on each of the 10 teeth; Kappa was found to be 0.90, indicating high interexaminer reliability. Two
Opalescence Quick which contains 45% carbamide peroxide [21]. Previous studies in this regard suffer some pitfalls including the use of unsafe machines to generate ozone [8,21], which followed experimental settings that cannot be applied for clinical settings [21], used subjective visual shade guides to record shade changes [19,21], used very small sample sizes [18,20], used very low concentrations of peroxide [18], primarily assessed extrinsic artificial staining from tea [18] or recorded hue component of the shade only [19]. Numerous studies are present in the textile and pollution literature showing the synergistic benefits of using ozone with peroxide for bleaching and degradation of pollutants and industrial waste products and this is often called advanced oxidative processes [22–26]. This incited the conduction of this study to shed more light on the role of ozone in dental bleaching and to compare its efficacy with conventional bleaching agents. The aim of this study was to evaluate the efficacy of bleaching using both 38% H2O2 and 60 s of ozone applied to teeth for 20 min in comparison to the sole use of 38% H2O2 for 20 min. The null hypothesis for this study was that combining application of both 38% H2O2 and 60 s of ozone applied to teeth for 20 min has similar bleaching effects in comparison to the sole use of 38% H2O2 also applied for 20 min. 2. Materials and methods Seventy freshly extracted human teeth including incisors, canines and premolars were used in this study. The study was approved by the Deanship of Research, University of Jordan, Amman, Jordan. Each tooth was cleaned using normal saline and gauze; and then stored in a 5% thymol solution at room temperature to prevent dehydration of teeth [27]. Thymol solution has an antimicrobial action and was used to store the specimens during the period of tooth collection for this study [27]. A condensation silicone mold was fabricated for each tooth to make it easier to handle the teeth during the study. The teeth were randomly allocated into two groups after giving each tooth mold a specific number then the teeth were distributed randomly to either group 1 or 2. To detect changes in the shade of each tooth surface, the shade of teeth was evaluated for both groups at base line. The shade was recorded using the Colorimeter Konica-Minolta CR-400 (Minolta Inc, Osaka, Japan). Colorimeters measure the intensity of reflected visible light for red, green, blue and yellow wave lengths (i.e. the coordinates of color space in CIELAB color system) [28,29]. The used colorimeter gives the reading for L* a* b* values and Vita Classic shades. L* a* b* values refer to the dimensions of color space and spatial presentation of the CIELAB color system through the use of L* a* b* coordinates; where L* determines lightness, a* determines redness (+a*) or greenness ( a*), and b* determines yellowness (+b*) or blueness ( b*) [30]. L* value ranges between zero and 100, a* value ranges between 90 and 70, and b* value ranges between 80 and 100. Table 1 Distribution of L* a* b* shade values among study groups before and after bleaching. Group
L* value (SD) Baseline
After bleaching
Group 1 (bleaching with H2O2 + ozone) Group 2 (bleaching with H2O2 + air) Group 2 (bleaching with ozone for teeth already bleached with H2O2 + air)
81.64(3.43) 81.79(3.00) 83.76(3.19)
85.07(2.90) 83.76(3.19) 84.91(2.83)
a* value (SD) Baseline 1.75(1.99) 1.98(1.96) 2.63(1.78)
b* value (SD) After bleaching 2.29(1.53) 2.63(1.78) 2.74(1.77)
Baseline
After bleaching
17.32(4.25) 17.45(5.61) 15.56(3.59)
12.97(3.60) 15.56(3.59) 12.82(3.15)
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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Table 2 Differences in shade values of study samples before and after bleaching using paired samples t-test. Group
Vita shade pairs
Paired differences Std. error mean
t
Vita baseline –Vita final L* baseline –L* final a* baseline –a* final b* baseline –b* final Vita baseline –Vita final L* baseline –L* final a* baseline –a* final b* baseline –b* final
2
0.14651 0.44064 0.27536 0.57440 0.12636 0.37895 0.33251 0.84723
Sig. (2-tailed)
34 34 34 34 34 34 34 34
0.000 0.000 0.056 0.000 0.000 0.000 0.062 0.032
95% Confidence interval of the difference Lower
1
df
Upper
0.81655 4.32978 0.01388 3.18124 0.74321 2.74440 0.03345 0.16964
1.41203 2.53879 1.10530 5.51590 1.25679 1.20417 1.31802 3.61321
7.606 7.794 1.982 7.571 7.914 5.210 1.932 2.232
Group 1 = teeth bleached with H2O2 and ozone, group 2 = teeth bleached with H2O2 then air.
operators carried out the experiment. One operator did the bleaching for all samples (M.K.AL-O.) and the other recorded all the shades for the samples (R.S.A.H.) in this study. The operator who did the shade readings was blinded to which treatment had been applied to each tooth. 2.1. Statistical analysis The data were analyzed using the SPSS computer software (Statistical Package for the Social Sciences; version 19.0, SPSS Inc.). The Pearson Correlation test was used to test for correlation between shade values at base line and after application of H2O2, ozone or both. Paired sample t-test was used to compare shade values before and after bleaching. For all statistical analyses, significance levels were set at P 0.05. In order to ensure the use of the most appropriate statistical methods and to avoid statistical errors, the statistical analyses methods used in this study are supported with the conclusions and recommendations suggested by Hannigan and Lynch [33]. 3. Results Table 1 shows the distribution of L* a* b* shade values among study groups before and after bleaching. Using both bleaching protocols was associated with changes in L* a* b* shade values. L*
values were increased following bleaching in both groups; meanwhile, a* and b* values were decreased following bleaching. Table 2 presents the differences between shade values before and after bleaching among the study sample. Baseline Vita shades were improved to lighter shades following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P < 0.001). Also, baseline L* shade values were increased (means lighter shades) following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P < 0.001). In addition, baseline a* shade values were not significantly changed following bleaching in groups 1 and 2 (P = 0.056 and 0.062 respectively). Also, baseline b* shade values were reduced (means lighter shades) following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P = 0.032). Table 3 demonstrates the analysis of variance to compare baseline and final shade values between groups. Baseline Vita, L* a* and b* shade values in group 1 were comparable to baseline shade values in group 2 (P > 0.05). On the other hand; final Vita, L*, and b* shade values in group 1 were significantly different from those in group 2 (P = 0.002, 0.000, and 0.004, respectively). In group 1, final Vita shades were lighter, final L* shade values were higher (lighter shades), and final b* shade values were lower (lighter shades) than those in group 2. However, final a* shade values were not significantly different between groups (P = 0.402).
Table 3 Analysis of variance of shade values between groups before and following bleaching. Shade value Baseline vita
Final vita
Baseline L*
Baseline a*
Baseline b*
Final L*
Final a*
Final b*
Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total
Sum of squares
df
0.357 63.286 63.643 3.004 19.243 22.246 0.401 706.777 707.178 0.989 266.038 267.027 0.316 1683.037 1683.353 155.109 447.786 602.895 1.956 187.154 189.110 117.521 878.059 995.581
1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69
Mean square
F
Sig. (P value)
0.357 0.931
0.384
0.538
3.004 0.283
10.614
0.002
0.401 10.394
0.039
0.845
0.989 3.912
0.253
0.617
0.316 24.751
0.013
0.910
155.109 6.585
23.555
0.000
1.956 2.752
0.711
0.402
117.521 12.913
9.101
0.004
df = degree of freedom; Sig = significance; F = F statistics.
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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Table 4 Changes in Vita, L*, a*, and b* shade values within group 2 following ozone bleaching of teeth already bleached with H2O2 (n = 35). Group
Vita shade pairs
Paired differences Std. error mean
t
Vita final–Vita final after further ozone bleaching L* final–L* final after further ozone bleaching a* final–a* final after further ozone bleaching b* final–b* final after further ozone bleaching Vita baseline–Vita final after further ozone bleaching L* baseline–L* after further ozone bleaching a* baseline–a* final after further ozone bleaching b* baseline–b* final after further ozone bleaching
0.09720 0.20152 0.16430 0.38526 0.15269 0.41613 0.36297 0.86492
Sig. (2-tailed)
34 34 34 34 34 34 34 34
0.000 0.000 0.001 0.000 0.000 0.000 0.877 0.000
95% confidence interval of the difference Lower
2
df
0.21675 1.55811 0.91961 1.95706 1.10399 3.96853 0.68108 2.87371
Upper 0.61182 0.73903 0.25182 3.52294 1.72458 2.27719 0.79422 6.38915
4.262 5.699 3.565 7.112 9.263 7.505 0.156 5.355
Group 2 = teeth bleached with H2O2 then air.
Table 4 shows the changes in shade values within group 2 following further ozone bleaching of teeth already bleached with H2O2. This within group 2 comparison revealed that Vita, L* a* and b* shade values were all significantly changed (P 0.001). So, within group 2; Vita shades became lighter, L* shade values increased, a* shade values decreased, and b* shade values decreased. Furthermore, in comparison to baseline shade values of group 2; further bleaching with ozone was associated with significant changes in Vita, L* and b* shade values (P < 0.001). However, baseline a* values were not significantly changed (P = 0.877) (Table 4). 4. Discussion This study showed that bleaching with 38% H2O2 for 20 min with application of ozone for 60 s resulted in teeth with lighter shades than bleaching with 38% H2O2 and air. Therefore, the null hypothesis of the study was rejected. Although different ozone generating machines are used in dentistry, the healOzone machine was used to provide ozone in this study as it has been and is extensively used worldwide for dental patients and been proven to be safe for human use due to the strict containment of ozone in the machine system and the requirement of perfect seal of its delivery system before it provides ozone [8,12,13,15,34]. Miller and Hodson concluded that the Ozicure device would cause ozone concentrations to reach unsafe levels in the respiratory system especially if used without effective suction; and therefore should not be used [8]. On the other hand, the healOzone machine was safe to use for humans as it is designed to work only if the delivering cups ensure a perfect seal to prevent ozone escape from the machine system [8,12,13,15,34]. Shade measurements were standardized in this study by using a specially designed measuring booth with standardized illumination and a standardized measurement distance following previous recommendations [31,35]. Lighter shades of the teeth were obtained following bleaching with H2O2 and ozone or with H2O2 and air. This is mainly due to the free radicals that have potent bleaching effects capable of color removal. This concurs with the results of previous studies which demonstrated that ozone could lighten tetracycline stained incisor teeth in rats [19] and could bleach teeth similar to Opalescnce Quick [21]. Nevertheless, it contrasts with the results of Manton et al. who found that 8% carbamide peroxide bleaching efficiency was not improved by using ozone [18]. This difference could be due to variations in sample size and study design as they used an early different machine that produced less ozone concentrations, applied ozone for 40 s only, tested a small sample size of only 10 samples per group, primarily assessed tea stain removal, used carbamide peroxide instead of hydrogen peroxide which needs much more time to be effective and also used only 8% carbamide
peroxide which is about 12 times less peroxide concentration than used in this study. In addition, Manton et al. did not attempt to quantify the ppm of ozone delivered nor the flow rate [18]. However, more bleaching effect was obtained when ozone was used with H2O2. This could be due to ozone providing a rich continuous source of superoxide (O) and ozone when combined with peroxide increases the release of hydroxyl radicals (OH) that are known to have a very potent effect on color removal. After all, ozone is also considered the third most potent oxidant after fluorine and persulfate [1,2]. On the other hand, H2O2 is slow to decompose to produce free radicals so it has limits for fast bleaching unless it is activated and H2O2 is a much weaker oxidant than ozone. Also, ozone is more controllable than H2O2 as once H2O2 is activated by ozone it would produce ions and free radicals much more under the control of the operator. Ozone is easy to control as it is provided by this special machine that can control the concentration, volume, delivery site and timing of delivered ozone. This study demonstrated that bleaching with both H2O2 and ozone would enhance the shades of teeth more than bleaching with H2O2 alone. In addition, the application of ozone on teeth already bleached with H2O2 further enhanced the bleaching of teeth. It is probable these teeth had retained some of the originally applied hydrogen peroxide. Ozone seemed to potentiate the bleaching effects of H2O2 in a very quick time. The air was delivered so as to negate any potential desiccation effect of the delivery with ozone. The ozone reacted with the peroxide on the teeth to produce the classic advanced oxidative processes. This will especially have occurred as 38% peroxide was used and it was not in the form of carbamide peroxide which would have needed a considerable amount of time to first break down to urea and hydrogen peroxide. Only after this latter step is the peroxide available to bleach. This can be another reason to help explain the surprising finding in the Manton et al. [18] study. This Manton et al. [18] study also used teeth which had been stained using a strong tea infusion incubated for a total of 20 days which would have been mainly assessing external staining instead of real tooth internal bleaching. Therefore, it is reasonable to apply ozone following application of H2O2 as this should potentially improve bleaching results. This might potentially reduce treatment cost and time, might reduce the potential for tissue irritation and tooth sensitivity and might increase patients’ compliance with and acceptance of treatment. Nevertheless, further research is required to verify and establish these potentials as they were not investigated in this study. Also, ozone does not irritate soft tissues around teeth while H2O2 is very irritant to the soft tissues and requires careful application including gingival masks. The use of ozone is measurable, controllable, quick, less irritant to soft tissues, and does not require light activation that could potentially affect the eyes.
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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The synergistic effects of combining ozone and peroxide are not surprising given the large number of studies proving this increased oxidation effect outside dentistry [22–26]. The study limitations are that this study was conducted on non vital extracted human teeth under a controlled environment which does not copy the intraoral settings. However, the controlled settings helped the standardization of the applied procedures and measurements. Also, dehydration of teeth during the experiment might affect tooth color and thus might affect the obtained results. However, application of ozone in group 1or air in group 2 was done into the H2O2 gel layer and this prevented the teeth from being dehydrated. Also, teeth were stored in thymol solution before being used for the purpose of this study so they were prevented from being dehydrated. Furthermore, after rinsing the whitening gel the teeth were exposed to only 2 s of air from the three-in-one syringe which is not enough to dry the tooth. Also, the size of the study sample is small; however, the number of samples in this study is comparable to or even larger than previous studies in this field [15–19,21]. In addition, the use of high hydrogen peroxide concentrations (38%) in this study does not meet the new recommendations in Europe where the maximum allowed concentration of hydrogen peroxide is 6%. However, using such high concentrations of hydrogen peroxide is still acceptable clinical practice in most countries across the world. The used hydrogen peroxide concentrations in this study were justified as they were applied to extracted teeth and were used to produce quicker and easily measurable effects on the samples without the need for multiple applications of the gel for longer durations. Further studies are recommended on larger samples and in clinical settings to adequately measure the potential bleaching effects of ozone on the natural dentition. Also, further studies are recommended to evaluate the potential effects of ozone for bleaching difficult dental stains such as those present in patients affected with fluorosis and tetracycline staining. In addition, future studies are recommended to determine whether statistically significant color changes to teeth would be visibly detectable by the public including patients and lay people. Also, further studies on whether it is required to do further clinically home based bleaching after ozone bleaching and whether the overall results after that is different due to the application of ozone. More ex vivo studies are in progress to also assess the effect of ozone on teeth treated with 6% hydrogen peroxide. It would be interesting to ascertain how low the percentage of peroxide which can be used in combination with ozone to mimic the bleaching efficacy of 38% peroxide. Any reduction in peroxide concentration can have many potential clinical benefits by reducing the complications of peroxide use [36,37]. European law also now only permits a maximum concentration of 6% peroxide for tooth whitening. 5. Conclusions Within the limitations of this study; it was concluded that teeth obtained lighter shades following bleaching with both 20 min of 38% H2O2 and 60 s of ozone application as well as with 38% H2O2 and air alone. However, bleaching with both H2O2 and ozone resulted in more significant improvements of the shades of teeth than bleaching with H2O2 and air alone. The further application of ozone on teeth already bleached with H2O2 resulted in more significant improvements of the shades of teeth than bleaching with H2O2 alone. Also, teeth treated with both ozone and H2O2 were associated with more changes in L* and b* shade values than those treated with H2O2 alone. However, a* values were not significantly changed following bleaching with both protocols.
5
Conflict of interests The authors have no conflict of interests except for Edward Lynch who has been principal investigator for previous research grants awarded from Curozone to Queens University Belfast. None of the authors currently have any financial interest/ arrangements or affiliations with this German company and no expenses or fees are being paid in any way for this research from Curozone. Acknowledgements The authors would like to thank Mrs AbdelAziz for her assistance during the preparation of this study. Thanks to University of Jordan and Aljouf University for making this study possible. References [1] D.T. Burns, Early problems in the analysis and the determination of ozone, Fresenius J. Anal. Chem. 357 (1997) 178–183. [2] V.A. Bocci, Scientific and medical aspects of ozone therapy: state of the art, Arch. Med. Res. 37 (2006) 425–435. [3] C.G. Nogales, P.H. Ferrari, E.O. Kantorovich, J.L. Lage-Marques, Ozone therapy in medicine and dentistry, J. Contemp. Dent. Pract. 9 (2008) 75–84. [4] V. Seidler, I. Linetskiy, H. Hubálková, H. Stanková, R. Smucler, J. Mazánek, Ozone and its usage in general medicine and dentistry. A review article, Prague Med. Rep. 109 (2008) 5–13. [5] Rajiv Saini, Ozone therapy in dentistry: a strategic review, J. Nat. Sci. Biol. Med. 2 (2011) 151–153. [6] A. Baysan, R.A. Whiley, E. Lynch, Antimicrobial effect of a novel ozone generating device on micro-organisms associated with primary root carious lesions in vitro, Caries Res. 34 (2000) 498–501. [7] J. Holmes, Clinical reversal of root caries using ozone, double-blind, randomised, controlled 18-month trial, Gerodontology 20 (2003) 106–114. [8] B.J. Millar, N. Hodson, Assessment of the safety of two ozone delivery devices, J. Dent. 35 (2007) 195–200. [9] A. Baysan, E. Lynch, Clinical reversal of root caries using ozone: 6-month results, Am. J. Dent. 20 (2007) 203–208. [10] E. Lynch, Evidence-based efficacy of ozone for root canal irrigation, J. Esthet. Restor. Dent. 20 (2008) 287–293. [11] E. Lynch, Evidence-based caries reversal using ozone, J. Esthet. Restor. Dent. 20 (2008) 218–222. [12] P.T. Pires, J.C. Ferreira, S.A. Oliveira, M.J. Silva, P.R. Melo, Effect of ozone gas on the shear bond strength to enamel, J. Appl. Oral Sci. 21 (2013) 177–182. [13] A. Kapdan, N. Öztaş, Z. Sümer, Comparing the antibacterial activity of gaseous ozone and chlorhexidine solution on a tooth cavity model, J. Clin. Exp. Dent. 5 (2013) e133–7. [14] D.F. McKenna, A. Borzabadi-Farahani, E. Lynch, The effect of subgingival ozone and/or hydrogen peroxide on the development of peri-implant mucositis: a double-blind randomized controlled trial, Int. J. Oral Maxillofac. Implants 28 (2013) 1483–1489. [15] J.F. Bortolatto, H. Pretel, M.C. Floros, A.C. Luizzi, A.A. Dantas, E. Fernandez, G. Moncada de, O.B. de Oliveira Jr., Low concentration H2O2/TiO_N in office bleaching—a randomized clinical trial, J. Dent. Res. 93 (Suppl. (7)) (2014) 66S– 71S. [16] P.V. Patel, A. Patel, S. Kumar, J.C. Holmes, Effect of subgingival application of topical ozonated olive oil in the treatment of chronic periodontitis: a randomized, controlled, double blind, clinical and microbiological study, Minerva Stomatol. 61 (2012) 381–398. [17] H.O. Kazancioglu, E. Kurklu, S. Ezirganli, Effects of ozone therapy on pain, swelling, and trismus following third molar surgery, Int. J. Oral Maxillofac. Surg. 43 (2014) 644–648. [18] D.J. Manton, R. Bhide, M.S. Hopcraft, E.C. Reynolds, Effect of ozone and tooth mousse on the efficacy of peroxide bleaching, Aust. Dent. J. 53 (2008) 128–132. [19] J. Tessier, P.N. Rodriguez, F. Lifshitz, S.M. Friedman, E.J. Lanata, The use of ozone to lighten teeth. An experimental study, Acta Odontol. Latinoam. 23 (2010) 84– 89. [20] M. Abd Elhamid, R. Mosallam, Effect of bleaching versus repolishing on colour and surface topography of stained resin composite, Aust. Dent. J. 55 (2010) 390–398. [21] A.A. Grundlingh, E.S. Grossman, M.J. Witcomb, Tooth colour change with Ozicure Oxygen Activator: a comparative in vitro tooth bleaching study, South Afr. Dent. J. 67 (2012) 332–337. [22] E.C. Catalkaya, F. Kargi, Color TOC and AOX removals from pulp mill effluent by advanced oxidation processes: a comparative study, J. Hazard. Mater. 139 (2007) 244–253. [23] I. Arslan-Alaton, Degradation of a commercial textile biocide with advanced oxidation processes and ozone, J. Environ. Manage. 82 (2007) 145–154.
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Contents lists available at ScienceDirect
Journal of Dentistry journal homepage: www.intl.elsevierhealth.com/journals/jden
Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study Mahmoud K. AL-Omiria,b,* , Ra’ed S. Abul Hassanc, Bader K. AlZaread, Edward Lynche a
Faculty of Dentistry, University of Jordan, Amman, Jordan The City of London School of Dentistry, BPP University, UK Faculty of Allied Medical Sciences, The Royal University for Medical Sciences, Amman, Jordan d Faculty of Dentistry, AlJouf University, Sakaka, Saudi Arabia e Warwick Medical School, Coventry CV4 7AL, UK b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 5 November 2015 Received in revised form 21 January 2016 Accepted 24 January 2016 Available online xxx
Objectives: To evaluate the efficacy of tooth bleaching using ozone after hydrogen peroxide (H2O2) in comparison to the use of H2O2 alone. Methods: 70 extracted teeth were randomly distributed into two groups. Teeth surfaces in group 1 (n = 35) were treated using 38% H2O2 and then were exposed to ozone for 60 s and this ozonated peroxide mixture was left on the teeth for 20 min. Meanwhile, teeth in group 2 (n = 35) were treated with H2O2 38% for 20 min. The L* a* b* and Vita Classic shade values of teeth were evaluated in both groups at base line, after application of H2O2 and ozone in group 1, and after application of H2O2 and then again after another application of ozone in group 2. The statistically significant changes were set at P 0.05. Results: Baseline L* a* b* and Vita shade values were comparable between groups (P > 0.05). Teeth obtained lighter shades following bleaching with both H2O2 and ozone or with H2O2 alone (P 0.05). Further bleaching with ozone for teeth already bleached with H2O2 alone showed further improvement of the shades of teeth (P < 0.001). Teeth treated with H2O2 and ozone had more shade improvements than those only treated with H2O2 (P < 0.001). Also, L* values were increased while b* values were decreased (teeth obtained lighter shades) following bleaching in both groups (P 0.05). More changes were obtained when both ozone and H2O2 were used (P 0.05). Conclusions: Bleaching with 38% H2O2 and ozone resulted in teeth with lighter shades than bleaching with 38% H2O2 alone. ã 2016 Elsevier Ltd. All rights reserved.
Keywords: Ozone Hydrogen peroxide Bleaching HealOzone Tooth shade
1. Introduction Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. Ozone is the third most potent oxidant after fluorine and persulfate [1,2]. Also, it has analgesic properties, has a very potent antimicrobial activity (against bacteria, viruses, yeasts, and protozoa), and has the capacity to stimulate blood circulation and the immune response [1,2]. Such features justify the current interest in its application in medicine and dentistry; and therefore, ozone has been indicated for the treatment of more than 250 different pathologies [1–5]. Ozone therapy is used for many aspects in dentistry including biofilm purging, periodontal pocket disinfection, prevention and
* Corresponding author at: Faculty of Dentistry, The University of Jordan, Amman 11942, Jordan. E-mail address: [email protected] (M.K. AL-Omiri).
management of dental caries, treatment of exposed pulps, root canal treatment, tooth extraction, tooth sensitivity, TMJ treatment, exposed roots, pain control, infection control, acceleration of healing, tissue regeneration, control of halitosis, tooth surface remineralization, and bleaching [1–17]. Different ozone generating machines are used in dentistry including the healOzone and Ozicure machines [7–15]. Previous studies on ozone’s role in bleaching are scarce and reported conflicting results [18–21]. Manton et al. [18] found that 8% carbamide peroxide bleaching efficiency was not significantly improved by using ozone. However, Abd Elhamid and Mosallam [20] found that an ozonated gel had better bleaching effect and was associated with less surface roughness of bleached disc-shaped stained resin composite specimens when compared to 30% carbamide peroxide. Also, some researchers demonstrated that ozone could lighten tetracycline stained incisor teeth in rats [19]. Meanwhile, other researchers demonstrated that ozone could bleach teeth similar to
http://dx.doi.org/10.1016/j.jdent.2016.01.010 0300-5712/ ã 2016 Elsevier Ltd. All rights reserved.
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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The colorimeter was used in a custom made booth to standardize the ambient environment during measuring L* a* b* values of the sixteen Vita Classic shades. The colorimeter was fixed in the booth perpendicular to the measured teeth surfaces at a fixed distance of 7 cm away from the measured tooth surface. A cabinet (100 cm 90 cm 70 cm) that had a D65 light with 200– 300 foot candle intensity was used as the measuring booth following Ozcelik et al. [31] . The lighting unit of the measuring booth had three lamps mounted at different angles around the axis of the mounting unit to avoid creation of shadow and to obtain well distributed illumination at the measuring area. Moreover, lamps were turned on for 30 min before color measuring to produce stable and constant illumination following the recommendations of Gozalo-Diaz et al. [32]. The colorimeter was calibrated before each use by measuring a reference Vita Classic shade (B3) each time before tooth shade measurement under the same conditions. Then, the facial surfaces of teeth in group 1 (n = 35) were treated using 38% hydrogen peroxide professional whitening gel (BMS white 38%, BMS Dental, Italy) with ozone then immediately applied for 60 s into the peroxide on each tooth and this ozonated peroxide mixture was left on the teeth for 20 min. Next the teeth were gently rinsed with water for 5 s and gently air dried with a three in one syringe for 2 s. After that, the shade of teeth was recorded as above. The H2O2 gel was applied on teeth surfaces using mixing tips attached on a dual syringe that contains the whitening gel and provided by the manufacturer. The ozone was generated by the healozone1 X4 machine (healOzone1 X4, Curozone, Germany). The delivered ozone concentration was 2350 ppm at a flow rate of 615 cc per min [14]. The ozone was applied to teeth through special disposable silicone cups provided by the manufacturer. The used silicone cups ensured a complete seal and prevented ozone gas escape as the machine is designed to work only when the cup ensures a perfect seal, and thus this ensures the safety of the healOzone machine for human use [8]. All shade measurements were recorded in the region relating to what would have been the area of the tooth corresponding to where the center of the cup was located. Meanwhile, the facial surfaces of teeth in group 2 (n = 35) were treated using 38% H2O2 with air (instead of ozone) then immediately applied for 60 s into the peroxide and this airperoxide mixture was left on the teeth for 20 min in the way as described above. A specially designed healOzone was used which had a switch at the back of the device which was switched to deliver only air and no ozone. The shade of the teeth was then recorded by an assessor who was not aware of the delivery of ozone or just air. Then, the teeth in group 2 were further exposed to ozone treatment for 60 s and the shade was recorded again as above. Intraexaminer reliability was established with 10 duplicate shade readings on 10 teeth by the same investigator. Kappa was 0.92, indicating significant agreement as the measuring environment and criteria were standardized, clear and simple. Interexaminer reliability was also assessed by having another investigator record the same 10 shade readings on each of the 10 teeth; Kappa was found to be 0.90, indicating high interexaminer reliability. Two
Opalescence Quick which contains 45% carbamide peroxide [21]. Previous studies in this regard suffer some pitfalls including the use of unsafe machines to generate ozone [8,21], which followed experimental settings that cannot be applied for clinical settings [21], used subjective visual shade guides to record shade changes [19,21], used very small sample sizes [18,20], used very low concentrations of peroxide [18], primarily assessed extrinsic artificial staining from tea [18] or recorded hue component of the shade only [19]. Numerous studies are present in the textile and pollution literature showing the synergistic benefits of using ozone with peroxide for bleaching and degradation of pollutants and industrial waste products and this is often called advanced oxidative processes [22–26]. This incited the conduction of this study to shed more light on the role of ozone in dental bleaching and to compare its efficacy with conventional bleaching agents. The aim of this study was to evaluate the efficacy of bleaching using both 38% H2O2 and 60 s of ozone applied to teeth for 20 min in comparison to the sole use of 38% H2O2 for 20 min. The null hypothesis for this study was that combining application of both 38% H2O2 and 60 s of ozone applied to teeth for 20 min has similar bleaching effects in comparison to the sole use of 38% H2O2 also applied for 20 min. 2. Materials and methods Seventy freshly extracted human teeth including incisors, canines and premolars were used in this study. The study was approved by the Deanship of Research, University of Jordan, Amman, Jordan. Each tooth was cleaned using normal saline and gauze; and then stored in a 5% thymol solution at room temperature to prevent dehydration of teeth [27]. Thymol solution has an antimicrobial action and was used to store the specimens during the period of tooth collection for this study [27]. A condensation silicone mold was fabricated for each tooth to make it easier to handle the teeth during the study. The teeth were randomly allocated into two groups after giving each tooth mold a specific number then the teeth were distributed randomly to either group 1 or 2. To detect changes in the shade of each tooth surface, the shade of teeth was evaluated for both groups at base line. The shade was recorded using the Colorimeter Konica-Minolta CR-400 (Minolta Inc, Osaka, Japan). Colorimeters measure the intensity of reflected visible light for red, green, blue and yellow wave lengths (i.e. the coordinates of color space in CIELAB color system) [28,29]. The used colorimeter gives the reading for L* a* b* values and Vita Classic shades. L* a* b* values refer to the dimensions of color space and spatial presentation of the CIELAB color system through the use of L* a* b* coordinates; where L* determines lightness, a* determines redness (+a*) or greenness ( a*), and b* determines yellowness (+b*) or blueness ( b*) [30]. L* value ranges between zero and 100, a* value ranges between 90 and 70, and b* value ranges between 80 and 100. Table 1 Distribution of L* a* b* shade values among study groups before and after bleaching. Group
L* value (SD) Baseline
After bleaching
Group 1 (bleaching with H2O2 + ozone) Group 2 (bleaching with H2O2 + air) Group 2 (bleaching with ozone for teeth already bleached with H2O2 + air)
81.64(3.43) 81.79(3.00) 83.76(3.19)
85.07(2.90) 83.76(3.19) 84.91(2.83)
a* value (SD) Baseline 1.75(1.99) 1.98(1.96) 2.63(1.78)
b* value (SD) After bleaching 2.29(1.53) 2.63(1.78) 2.74(1.77)
Baseline
After bleaching
17.32(4.25) 17.45(5.61) 15.56(3.59)
12.97(3.60) 15.56(3.59) 12.82(3.15)
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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Table 2 Differences in shade values of study samples before and after bleaching using paired samples t-test. Group
Vita shade pairs
Paired differences Std. error mean
t
Vita baseline –Vita final L* baseline –L* final a* baseline –a* final b* baseline –b* final Vita baseline –Vita final L* baseline –L* final a* baseline –a* final b* baseline –b* final
2
0.14651 0.44064 0.27536 0.57440 0.12636 0.37895 0.33251 0.84723
Sig. (2-tailed)
34 34 34 34 34 34 34 34
0.000 0.000 0.056 0.000 0.000 0.000 0.062 0.032
95% Confidence interval of the difference Lower
1
df
Upper
0.81655 4.32978 0.01388 3.18124 0.74321 2.74440 0.03345 0.16964
1.41203 2.53879 1.10530 5.51590 1.25679 1.20417 1.31802 3.61321
7.606 7.794 1.982 7.571 7.914 5.210 1.932 2.232
Group 1 = teeth bleached with H2O2 and ozone, group 2 = teeth bleached with H2O2 then air.
operators carried out the experiment. One operator did the bleaching for all samples (M.K.AL-O.) and the other recorded all the shades for the samples (R.S.A.H.) in this study. The operator who did the shade readings was blinded to which treatment had been applied to each tooth. 2.1. Statistical analysis The data were analyzed using the SPSS computer software (Statistical Package for the Social Sciences; version 19.0, SPSS Inc.). The Pearson Correlation test was used to test for correlation between shade values at base line and after application of H2O2, ozone or both. Paired sample t-test was used to compare shade values before and after bleaching. For all statistical analyses, significance levels were set at P 0.05. In order to ensure the use of the most appropriate statistical methods and to avoid statistical errors, the statistical analyses methods used in this study are supported with the conclusions and recommendations suggested by Hannigan and Lynch [33]. 3. Results Table 1 shows the distribution of L* a* b* shade values among study groups before and after bleaching. Using both bleaching protocols was associated with changes in L* a* b* shade values. L*
values were increased following bleaching in both groups; meanwhile, a* and b* values were decreased following bleaching. Table 2 presents the differences between shade values before and after bleaching among the study sample. Baseline Vita shades were improved to lighter shades following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P < 0.001). Also, baseline L* shade values were increased (means lighter shades) following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P < 0.001). In addition, baseline a* shade values were not significantly changed following bleaching in groups 1 and 2 (P = 0.056 and 0.062 respectively). Also, baseline b* shade values were reduced (means lighter shades) following the use of H2O2 and ozone in group 1 (P < 0.001) and following the use of H2O2 and air in group 2 (P = 0.032). Table 3 demonstrates the analysis of variance to compare baseline and final shade values between groups. Baseline Vita, L* a* and b* shade values in group 1 were comparable to baseline shade values in group 2 (P > 0.05). On the other hand; final Vita, L*, and b* shade values in group 1 were significantly different from those in group 2 (P = 0.002, 0.000, and 0.004, respectively). In group 1, final Vita shades were lighter, final L* shade values were higher (lighter shades), and final b* shade values were lower (lighter shades) than those in group 2. However, final a* shade values were not significantly different between groups (P = 0.402).
Table 3 Analysis of variance of shade values between groups before and following bleaching. Shade value Baseline vita
Final vita
Baseline L*
Baseline a*
Baseline b*
Final L*
Final a*
Final b*
Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total Between groups Within groups Total
Sum of squares
df
0.357 63.286 63.643 3.004 19.243 22.246 0.401 706.777 707.178 0.989 266.038 267.027 0.316 1683.037 1683.353 155.109 447.786 602.895 1.956 187.154 189.110 117.521 878.059 995.581
1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69 1 68 69
Mean square
F
Sig. (P value)
0.357 0.931
0.384
0.538
3.004 0.283
10.614
0.002
0.401 10.394
0.039
0.845
0.989 3.912
0.253
0.617
0.316 24.751
0.013
0.910
155.109 6.585
23.555
0.000
1.956 2.752
0.711
0.402
117.521 12.913
9.101
0.004
df = degree of freedom; Sig = significance; F = F statistics.
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Table 4 Changes in Vita, L*, a*, and b* shade values within group 2 following ozone bleaching of teeth already bleached with H2O2 (n = 35). Group
Vita shade pairs
Paired differences Std. error mean
t
Vita final–Vita final after further ozone bleaching L* final–L* final after further ozone bleaching a* final–a* final after further ozone bleaching b* final–b* final after further ozone bleaching Vita baseline–Vita final after further ozone bleaching L* baseline–L* after further ozone bleaching a* baseline–a* final after further ozone bleaching b* baseline–b* final after further ozone bleaching
0.09720 0.20152 0.16430 0.38526 0.15269 0.41613 0.36297 0.86492
Sig. (2-tailed)
34 34 34 34 34 34 34 34
0.000 0.000 0.001 0.000 0.000 0.000 0.877 0.000
95% confidence interval of the difference Lower
2
df
0.21675 1.55811 0.91961 1.95706 1.10399 3.96853 0.68108 2.87371
Upper 0.61182 0.73903 0.25182 3.52294 1.72458 2.27719 0.79422 6.38915
4.262 5.699 3.565 7.112 9.263 7.505 0.156 5.355
Group 2 = teeth bleached with H2O2 then air.
Table 4 shows the changes in shade values within group 2 following further ozone bleaching of teeth already bleached with H2O2. This within group 2 comparison revealed that Vita, L* a* and b* shade values were all significantly changed (P 0.001). So, within group 2; Vita shades became lighter, L* shade values increased, a* shade values decreased, and b* shade values decreased. Furthermore, in comparison to baseline shade values of group 2; further bleaching with ozone was associated with significant changes in Vita, L* and b* shade values (P < 0.001). However, baseline a* values were not significantly changed (P = 0.877) (Table 4). 4. Discussion This study showed that bleaching with 38% H2O2 for 20 min with application of ozone for 60 s resulted in teeth with lighter shades than bleaching with 38% H2O2 and air. Therefore, the null hypothesis of the study was rejected. Although different ozone generating machines are used in dentistry, the healOzone machine was used to provide ozone in this study as it has been and is extensively used worldwide for dental patients and been proven to be safe for human use due to the strict containment of ozone in the machine system and the requirement of perfect seal of its delivery system before it provides ozone [8,12,13,15,34]. Miller and Hodson concluded that the Ozicure device would cause ozone concentrations to reach unsafe levels in the respiratory system especially if used without effective suction; and therefore should not be used [8]. On the other hand, the healOzone machine was safe to use for humans as it is designed to work only if the delivering cups ensure a perfect seal to prevent ozone escape from the machine system [8,12,13,15,34]. Shade measurements were standardized in this study by using a specially designed measuring booth with standardized illumination and a standardized measurement distance following previous recommendations [31,35]. Lighter shades of the teeth were obtained following bleaching with H2O2 and ozone or with H2O2 and air. This is mainly due to the free radicals that have potent bleaching effects capable of color removal. This concurs with the results of previous studies which demonstrated that ozone could lighten tetracycline stained incisor teeth in rats [19] and could bleach teeth similar to Opalescnce Quick [21]. Nevertheless, it contrasts with the results of Manton et al. who found that 8% carbamide peroxide bleaching efficiency was not improved by using ozone [18]. This difference could be due to variations in sample size and study design as they used an early different machine that produced less ozone concentrations, applied ozone for 40 s only, tested a small sample size of only 10 samples per group, primarily assessed tea stain removal, used carbamide peroxide instead of hydrogen peroxide which needs much more time to be effective and also used only 8% carbamide
peroxide which is about 12 times less peroxide concentration than used in this study. In addition, Manton et al. did not attempt to quantify the ppm of ozone delivered nor the flow rate [18]. However, more bleaching effect was obtained when ozone was used with H2O2. This could be due to ozone providing a rich continuous source of superoxide (O) and ozone when combined with peroxide increases the release of hydroxyl radicals (OH) that are known to have a very potent effect on color removal. After all, ozone is also considered the third most potent oxidant after fluorine and persulfate [1,2]. On the other hand, H2O2 is slow to decompose to produce free radicals so it has limits for fast bleaching unless it is activated and H2O2 is a much weaker oxidant than ozone. Also, ozone is more controllable than H2O2 as once H2O2 is activated by ozone it would produce ions and free radicals much more under the control of the operator. Ozone is easy to control as it is provided by this special machine that can control the concentration, volume, delivery site and timing of delivered ozone. This study demonstrated that bleaching with both H2O2 and ozone would enhance the shades of teeth more than bleaching with H2O2 alone. In addition, the application of ozone on teeth already bleached with H2O2 further enhanced the bleaching of teeth. It is probable these teeth had retained some of the originally applied hydrogen peroxide. Ozone seemed to potentiate the bleaching effects of H2O2 in a very quick time. The air was delivered so as to negate any potential desiccation effect of the delivery with ozone. The ozone reacted with the peroxide on the teeth to produce the classic advanced oxidative processes. This will especially have occurred as 38% peroxide was used and it was not in the form of carbamide peroxide which would have needed a considerable amount of time to first break down to urea and hydrogen peroxide. Only after this latter step is the peroxide available to bleach. This can be another reason to help explain the surprising finding in the Manton et al. [18] study. This Manton et al. [18] study also used teeth which had been stained using a strong tea infusion incubated for a total of 20 days which would have been mainly assessing external staining instead of real tooth internal bleaching. Therefore, it is reasonable to apply ozone following application of H2O2 as this should potentially improve bleaching results. This might potentially reduce treatment cost and time, might reduce the potential for tissue irritation and tooth sensitivity and might increase patients’ compliance with and acceptance of treatment. Nevertheless, further research is required to verify and establish these potentials as they were not investigated in this study. Also, ozone does not irritate soft tissues around teeth while H2O2 is very irritant to the soft tissues and requires careful application including gingival masks. The use of ozone is measurable, controllable, quick, less irritant to soft tissues, and does not require light activation that could potentially affect the eyes.
Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010
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The synergistic effects of combining ozone and peroxide are not surprising given the large number of studies proving this increased oxidation effect outside dentistry [22–26]. The study limitations are that this study was conducted on non vital extracted human teeth under a controlled environment which does not copy the intraoral settings. However, the controlled settings helped the standardization of the applied procedures and measurements. Also, dehydration of teeth during the experiment might affect tooth color and thus might affect the obtained results. However, application of ozone in group 1or air in group 2 was done into the H2O2 gel layer and this prevented the teeth from being dehydrated. Also, teeth were stored in thymol solution before being used for the purpose of this study so they were prevented from being dehydrated. Furthermore, after rinsing the whitening gel the teeth were exposed to only 2 s of air from the three-in-one syringe which is not enough to dry the tooth. Also, the size of the study sample is small; however, the number of samples in this study is comparable to or even larger than previous studies in this field [15–19,21]. In addition, the use of high hydrogen peroxide concentrations (38%) in this study does not meet the new recommendations in Europe where the maximum allowed concentration of hydrogen peroxide is 6%. However, using such high concentrations of hydrogen peroxide is still acceptable clinical practice in most countries across the world. The used hydrogen peroxide concentrations in this study were justified as they were applied to extracted teeth and were used to produce quicker and easily measurable effects on the samples without the need for multiple applications of the gel for longer durations. Further studies are recommended on larger samples and in clinical settings to adequately measure the potential bleaching effects of ozone on the natural dentition. Also, further studies are recommended to evaluate the potential effects of ozone for bleaching difficult dental stains such as those present in patients affected with fluorosis and tetracycline staining. In addition, future studies are recommended to determine whether statistically significant color changes to teeth would be visibly detectable by the public including patients and lay people. Also, further studies on whether it is required to do further clinically home based bleaching after ozone bleaching and whether the overall results after that is different due to the application of ozone. More ex vivo studies are in progress to also assess the effect of ozone on teeth treated with 6% hydrogen peroxide. It would be interesting to ascertain how low the percentage of peroxide which can be used in combination with ozone to mimic the bleaching efficacy of 38% peroxide. Any reduction in peroxide concentration can have many potential clinical benefits by reducing the complications of peroxide use [36,37]. European law also now only permits a maximum concentration of 6% peroxide for tooth whitening. 5. Conclusions Within the limitations of this study; it was concluded that teeth obtained lighter shades following bleaching with both 20 min of 38% H2O2 and 60 s of ozone application as well as with 38% H2O2 and air alone. However, bleaching with both H2O2 and ozone resulted in more significant improvements of the shades of teeth than bleaching with H2O2 and air alone. The further application of ozone on teeth already bleached with H2O2 resulted in more significant improvements of the shades of teeth than bleaching with H2O2 alone. Also, teeth treated with both ozone and H2O2 were associated with more changes in L* and b* shade values than those treated with H2O2 alone. However, a* values were not significantly changed following bleaching with both protocols.
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Conflict of interests The authors have no conflict of interests except for Edward Lynch who has been principal investigator for previous research grants awarded from Curozone to Queens University Belfast. None of the authors currently have any financial interest/ arrangements or affiliations with this German company and no expenses or fees are being paid in any way for this research from Curozone. Acknowledgements The authors would like to thank Mrs AbdelAziz for her assistance during the preparation of this study. Thanks to University of Jordan and Aljouf University for making this study possible. References [1] D.T. Burns, Early problems in the analysis and the determination of ozone, Fresenius J. Anal. Chem. 357 (1997) 178–183. [2] V.A. Bocci, Scientific and medical aspects of ozone therapy: state of the art, Arch. Med. Res. 37 (2006) 425–435. [3] C.G. Nogales, P.H. Ferrari, E.O. Kantorovich, J.L. Lage-Marques, Ozone therapy in medicine and dentistry, J. Contemp. Dent. Pract. 9 (2008) 75–84. [4] V. Seidler, I. Linetskiy, H. Hubálková, H. Stanková, R. Smucler, J. Mazánek, Ozone and its usage in general medicine and dentistry. A review article, Prague Med. Rep. 109 (2008) 5–13. [5] Rajiv Saini, Ozone therapy in dentistry: a strategic review, J. Nat. Sci. Biol. Med. 2 (2011) 151–153. [6] A. Baysan, R.A. Whiley, E. Lynch, Antimicrobial effect of a novel ozone generating device on micro-organisms associated with primary root carious lesions in vitro, Caries Res. 34 (2000) 498–501. [7] J. Holmes, Clinical reversal of root caries using ozone, double-blind, randomised, controlled 18-month trial, Gerodontology 20 (2003) 106–114. [8] B.J. Millar, N. Hodson, Assessment of the safety of two ozone delivery devices, J. Dent. 35 (2007) 195–200. [9] A. Baysan, E. Lynch, Clinical reversal of root caries using ozone: 6-month results, Am. J. Dent. 20 (2007) 203–208. [10] E. Lynch, Evidence-based efficacy of ozone for root canal irrigation, J. Esthet. Restor. Dent. 20 (2008) 287–293. [11] E. Lynch, Evidence-based caries reversal using ozone, J. Esthet. Restor. Dent. 20 (2008) 218–222. [12] P.T. Pires, J.C. Ferreira, S.A. Oliveira, M.J. Silva, P.R. Melo, Effect of ozone gas on the shear bond strength to enamel, J. Appl. Oral Sci. 21 (2013) 177–182. [13] A. Kapdan, N. Öztaş, Z. Sümer, Comparing the antibacterial activity of gaseous ozone and chlorhexidine solution on a tooth cavity model, J. Clin. Exp. Dent. 5 (2013) e133–7. [14] D.F. McKenna, A. Borzabadi-Farahani, E. Lynch, The effect of subgingival ozone and/or hydrogen peroxide on the development of peri-implant mucositis: a double-blind randomized controlled trial, Int. J. Oral Maxillofac. Implants 28 (2013) 1483–1489. [15] J.F. Bortolatto, H. Pretel, M.C. Floros, A.C. Luizzi, A.A. Dantas, E. Fernandez, G. Moncada de, O.B. de Oliveira Jr., Low concentration H2O2/TiO_N in office bleaching—a randomized clinical trial, J. Dent. Res. 93 (Suppl. (7)) (2014) 66S– 71S. [16] P.V. Patel, A. Patel, S. Kumar, J.C. Holmes, Effect of subgingival application of topical ozonated olive oil in the treatment of chronic periodontitis: a randomized, controlled, double blind, clinical and microbiological study, Minerva Stomatol. 61 (2012) 381–398. [17] H.O. Kazancioglu, E. Kurklu, S. Ezirganli, Effects of ozone therapy on pain, swelling, and trismus following third molar surgery, Int. J. Oral Maxillofac. Surg. 43 (2014) 644–648. [18] D.J. Manton, R. Bhide, M.S. Hopcraft, E.C. Reynolds, Effect of ozone and tooth mousse on the efficacy of peroxide bleaching, Aust. Dent. J. 53 (2008) 128–132. [19] J. Tessier, P.N. Rodriguez, F. Lifshitz, S.M. Friedman, E.J. Lanata, The use of ozone to lighten teeth. An experimental study, Acta Odontol. Latinoam. 23 (2010) 84– 89. [20] M. Abd Elhamid, R. Mosallam, Effect of bleaching versus repolishing on colour and surface topography of stained resin composite, Aust. Dent. J. 55 (2010) 390–398. [21] A.A. Grundlingh, E.S. Grossman, M.J. Witcomb, Tooth colour change with Ozicure Oxygen Activator: a comparative in vitro tooth bleaching study, South Afr. Dent. J. 67 (2012) 332–337. [22] E.C. Catalkaya, F. Kargi, Color TOC and AOX removals from pulp mill effluent by advanced oxidation processes: a comparative study, J. Hazard. Mater. 139 (2007) 244–253. [23] I. Arslan-Alaton, Degradation of a commercial textile biocide with advanced oxidation processes and ozone, J. Environ. Manage. 82 (2007) 145–154.
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Please cite this article in press as: M.K. AL-Omiri, et al., Improved tooth bleaching combining ozone and hydrogen peroxide—A blinded study, Journal of Dentistry (2016), http://dx.doi.org/10.1016/j.jdent.2016.01.010