An Environmental Scanning Electron Microscopy Evaluation on Comparison of Three Different Bleaching Agents using the Laser Activated in-Office Bleaching at Different Wavelengths.

BACKGROUND: Shade of the teeth is of specific significance to the patient because of social and psychological concern and hence plays vital role as primary care. Bleaching is a noninvasive, relatively inexpensive, conservative, and low-maintenance method to change a smile dramatically. AIM: To study the effect of application of three bleaching agents at different wavelengths of laser on the enamel surface of teeth using an environmental scanning electron microscopy (ESEM).
MATERIALS AND METHODS: One hundred and twenty freshly extracted, noncarious intact maxillary central incisors were collected and stored in moist conditions in plastic containers. Using a randomized stratified design, the samples were divided into 12 groups (n = 10). The bleaching agent was mixed according to the manufacturer's instructions and applied on the enamel surface of the teeth followed by laser activation. The ultrastructural effects of the bleaching agent on the enamel were determined with an ESEM. Samples were assessed both before and after bleaching on the basis of the degree of surface damage. Because the observation by ESEM was designed to be qualitative, no statistical analysis was performed.
RESULTS: JW power bleaching agent and Opalescence Xtra boost showed minimum surface alteration when compared to Polaoffice. Furthermore, the groups treated with diode 810 nm showed less surface damage while neodymium-doped yttrium aluminum garnet 1064 nm more surface alterations than the groups treated with diodes.
CONCLUSION: From this current study, it can be concluded that the diode laser of 810 nm with JW power bleaching showed minimum surface alterations. Copyright:

INTRODUCTION

Teeth play a major role in the beauty and personality of the individual. Teeth discoloration is a common problem.[1] The desire to have whiter natural looking teeth and thus a more pleasant smile has become a major esthetic need of patients today, possibly correlating through the advent of social networks and digital photographs.[2] Bleaching of teeth has gained immense success in the past decade as it is a noninvasive, relatively inexpensive, conservative, low-maintenance method to change a smile dramatically.[345]

Hydrogen peroxide (30%–35% H2O2) is capable of generating a hydroxyl radical, oxygen derived free radical. Commercially available bleaching agents – JW power bleaching, Opalescence boost, Pola office, etc.[6] Carbamide Peroxide (CH6N2O)3 solutions of 10% break down into urea, ammonia, carbon dioxide, and approximately 3.5% hydrogen peroxide. A 35% solution yields 10% hydrogen peroxide and is available as to be used by the dentist as an in-office procedure before the patient using the home kit.[7] Commercially available bleaching agents – Colgate platinum over white, opalescence PF, opalescence quick, etc.[78] Sodium Perborate (Na[H2 (O2)2 (OH)]4) is an oxidizing agent marketed as powered and various commercial preparations forms, which decomposes to sodium metaborate, hydrogen peroxide, and nascent oxygen in the presence of acid, warm air, or water.[9]

Dental lasers can be used with bleaching agents containing the specific chromophore that will absorb the laser's wavelength. Laser is a comparatively novel approach for teeth whitening.[10] Mechanism of a laser system for bleaching relies on wavelength, power of radiation, and pump mode.[11] Lamps that emit long wavelengths have lower energy photons, causing high thermal that may induce unfavourable thermal effects. KTP, argon, and diode lasers are classically used for in-office bleaching treatments.[1213]

Lasers have also been known to produce some amount of surface alterations. We undertook this study to examine the effect of application of three bleaching agents activated at different wavelengths of laser on the enamel surface of teeth using environmental scanning electron microscopy (ESEM).

MATERIALS AND METHODS

Specimen preparation

Sample size was calculated using Power G analysis. One hundred and twenty freshly extracted, noncarious intact maxillary central incisors were collected, cleaned thoroughly and stored in moist conditions in plastic containers to avoid dehydration. Using a randomized stratified design, the samples were divided into 12 groups (n = 10): Group I – Polaoffice activated by Diode laser 810 nm, Group II – JW Power Bleaching activated by Diode laser 810 nm, Group III – Opalescence Xtra Boost activated by Diode laser 810 nm, Group IV – Polaoffice activated by Diode laser 940 nm, Group V – JW Power Bleaching activated by Diode laser 940 nm, Group VI – Opalescence Xtra Boost activated by Diode laser 940 nm, Group VII – Polaoffice activated by Diode laser 980 nm, Group VIII – JW Power Bleaching activated by Diode laser 980 nm, Group IX– Opalescence Xtra Boost activated by diode laser 980 nm, Group X – Polaoffice activated by neodymium-doped yttrium aluminum garnet (Nd: YAG) laser1064 nm, Group XI – JW Power bleaching activated by Nd: YAG laser 1064 nm, and Group XII – Opalescence Xtra Boost activated by Nd: YAG laser1064 nm. Samples from each group were taken for an ESEM study to the surface changes before and after bleaching [Figure 1].

Figure 1

ESEM images for the surface changes before and after bleaching. Group I – Polaoffice activated by Diode laser 810 nm, Group II – JW Power Bleaching activated by Diode laser 810 nm, Group III – Opalescence Xtra Boost activated by Diode laser 810 nm, Group IV – Polaoffice activated by Diode laser 940 nm, Group V – JW Power Bleaching activated by Diode laser 940 nm, Group VI – Opalescence Xtra Boost activated by Diode laser 940 nm, Group VII – Polaoffice activated by Diode laser 980 nm, Group VIII – JW Power Bleaching activated by Diode laser 980 nm, Group IX – Opalescence Xtra Boost activated by Diode laser 980 nm, Group X – Polaoffice activated by Nd: YAG laser 1064 nm, Group XI – JW Power Bleaching activated by Nd: YAG laser 1064 nm, Group XII – Opalescence Xtra Boost activated by Nd: YAG laser 1064 nm

Bleaching procedure

The bleaching agent was mixed according to the manufacturer's instructions and applied on the enamel surface of the teeth followed by laser activation with the following parameters: (1) diode 810 nm–2.5 watts, 20 s; (2) diode 940 nm-–2.5 watts, 20 s; (3) diode 980 nm–2.5 Watts, 20 s; and (4) Nd:YAG-2.5 Watts, 20 s. The present bleaching mode was used for diode lasers. For each sample, three cycles of bleaching were done and an interval of 20 s was taken in between each cycle. Before each cycle, the bleaching agent was removed, and the gel was rinsed off.

Evaluation of treatment effects (environmental scanning electron microscope)

ESEM was used to determine the ultrastructural effects of the bleaching agent on the enamel. Samples were analyzed both before and after bleaching on the basis of the degree of surface damage. Only sample pairs of the same tooth were compared and recorded. No statistical analysis was done, as the observation by ESEM was designed to be qualitative.

RESULTS

Group I-Diode 810 nm along with Polaoffice cracks, less distinct erosion with mild depressions, smooth lased appearance of treated surface were observed [Figure 1, Plate Ia, Ib]. Group II-Diode 810 nm along with JW Power Bleaching typical enamel surface morphology, smooth lased surface, mild irregularities were observed [Figure 1, Plate IIa, IIb]. Group III – Diode 810 nm along with Opalescence Xtra Boost smooth lased enamel, mild pitting were observed [Figure 1, Plate IIIa, IIIb]. Group IV – Diode 940 nm along with Polaoffice distinct erosion patterns, depressions, and aberrant crystals were observed [Figure 1, Plate IVa, IVb]. Group V – Diode 940 nm along with JW Power Bleaching no significant changes between pre- and postsamples except for lased enamel in postbleaching samples were observed [Figure 1: Plate Va, Vb]. Group VI – Diode 940 nm along with Opalescence Xtra Boost no surface alterations except for laser etched enamel pattern were observed [Figure 1: Plate VIa and VIb]. Group VII – Diode 980 nm along with Polaoffice mild surface erosion with generalized pitting was seen with a lased enamel surface, surface appeared to be dehydrated [Figure 1: Plate VIIa and VIIb]. Group VIII – Diode 980 nm along with JW Power Bleaching mild surface erosion with pitting was observed [Figure 1: Plate VIIIa and VIIIb]. Group IX – Diode 980 nm along with Opalescence Xtra Boost mild surface erosion with mild depressions was observed with lased enamel surface [Figure 1: Plate IXa and IXb]. Group X – Nd:YAG 1064 nm along with Polaoffice erosion pattern showed a loss of enamel prism cone with retained periphery resulting in generalized depressions on enamel surface, deep grooves, and scratches were observed [Figure 1, Plate Xa, Xb]. Group XI – Nd:YAG 1064 nm along with JW Power Bleaching mild erosion and generalized pitting was observed [Figure 1, Plate XIa, XIb]. Group XII – Nd:YAG 1064 nm along with Opalescence Xtra Boost distinct erosion pattern with generalized pitting was observed [Figure 1, Plate XIIa, XIIb].

DISCUSSION

In the current study, comparison between groups, on observation for diode 810 nm groups showed that among three bleaching agents used, JW power bleaching agent showed least surface alteration while polaoffice showed maximum surface destruction. For Diode 940 nm groups, Opalescence Xtra boost showed almost no surface alteration except for lased enamel surface while polaoffice showed some amount of surface destruction. For diode 980 nm groups, JW power bleaching agent showed least surface alteration while maximum surface destruction was observed with polaoffice. For Nd:YAG 1064 nm groups, JW power bleaching agent showed lesser surface alterations, in contrast to polaoffice which showed maximum surface alterations. However, among the different bleaching agents, overall JW power bleaching agent and Opalescence Xtra boost showed minimum surface alteration when compared to polaoffice. JW Power bleaching agent showed best results in terms of complete colour change, degree of tooth lightening, and surface alteration. No surface damage to minimum surface damage may attribute to the fact that this bleaching agent has least percentage of hydrogen peroxide (30%) recommended for in-office bleaching and secondly because of presence of titanium dioxide (TiO2) which is not present in other bleaching agents used. These results were confirmed by Goharkhay et al. who experimented with a gel which contained finely dispersed TiO2, which limited thermal transmission to the dental pulp.[10] Opalescence Xtra Boost showed significant results with minimum surface alterations. It contains of potassium nitrate and fluoride which is not seen in other two agents. It has been stated by several research studies that if the fluoride is incorporated into or adsorbed on the hydroxyapatite crystal, the crystal becomes more resistant to acid dissolution. This reaction explains the role of fluoride in enamel remineralization.[1415] Thus, even though the bleaching agent consist a high percentage of hydrogen peroxide minimum surface alterations are observed.

Present study states that amongst the different wavelengths of laser used, the groups treated with diode 810 nm showed less surface damage while Nd: YAG 1064 nm more surface alterations than the groups treated with diodes. The findings of this study also are in accordance with the study by Dostalova et al. where it was reported that the surface etching of the enamel can be lessen or forestall by using diode laser irradiation.[16] This confirmed previous studies by Anaraki et al. and de Paula Xavier et al. regarding the effect of diode laser on forestalling the roughening of enamel during bleaching.[1718] This is attributable to the in-depth activity of the laser-activated bleaching agent, when compared to the unspecific effect on the surface and depth of conventional bleaching.

According to Torres et al., treatments without photo activation or with photo activation using Nd: YAG laser were unable to efficiently catalyse hydrogen peroxide decomposition.[18] Wetter et al. reported significantly better results with diode laser photo activation in term of lightness when comparing dental bleaching efficacy with diode laser and LED.[19] Azarbayjani et al. in a study on effectiveness of diode laser bleaching in preventing enamel damage reported that diode laser at both wavelengths of 810 and 980 nm lessen the degree of enamel surface alteration that occurs during bleaching.[12] Although this study was carried out with optimal parameters and keeping all biases in check, it does have certain limitations. The present study being an in vitro study presents challenges of maintaining actual oral environment conditions hence the future could be an extension in the form of an in vivo one. Although this study was carried out with optimal parameters and keeping all biases in check, it does have certain limitations. Future studies should have an increased sample size to achieve better robustness of numerical evaluations.

CONCLUSION

For the reason of cosmetics and feel good factor for patients bleaching is the procedure carried out most commonly with an awareness of white naturally looking teeth. Within the limitations of this study, it can be concluded that the ESEM images reveal that overall among all groups, the diode laser of 810 nm with JW power bleaching showed minimum surface alterations.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.