Health Science Journal

Keywords

Hydrogen peroxide; Carbamide peroxide; Home bleaching; Office whitening 

Introduction

Performing cosmetic treatments is so subjective, because each individual has a standard regarding aesthetics; of course, there is a very large imposition of the media on aligned and clear teeth [1,2]. Beyond the eternal search for the fountain of youth and for this to achieved, there are multitudes of treatments and measuring the results of these is very difficult.

Dental dimming, especially in anterior teeth, causes discomfort to the individual and greatly undermines his confidence in smiling, causing a negative impact on their quality of life [3]. A dental bleaching is an excellent option for minimally invasive aesthetic solutions and which can applied alone or in conjunction with other treatments, and the main factor to be considered is the patients' perception of the results achieved [4].

Although bleaching is not a procedure with predictable results the success rate, as regards the appearance of the teeth, can reach 92% [5], but for this success to be achieved it is necessary to correctly diagnose the type of color change, planning the best way to solve the problem. Since 1868, tooth whitening has been increasingly used [6].

Therefore, the purpose of this clinical study was to compare the degree of bleaching visibly in clinical application between two office bleaching agents in vital teeth, being the 35% hydrogen peroxide and 37% carbamide peroxide.

Literature revision

Dental color changes may be extrinsic, caused by external factors such as food colorings and ingested foods, smoke and chromogenic bacteria that easily removed by prophylaxis or in some cases microabrasions [7]. Already the intrinsic alterations can be acquired or congenital [8], harder to remove. The acquired ones can have diverse causes like trauma, disorders, ingested medicines and physiological. In the congenital occurred in the formation of the structure of the dental germ. These indicated for whitening and in more severe cases of darkening there is a need for more invasive treatments [9].

Stain bleaching occurs by the oxidizing action of hydrogen peroxide. In addition, before starting tooth whitening it is necessary to know and determine the type of peroxide; hydrogen or carbamide, which technique; office, homesupervised or combined techniques and still define the best concentration of these agents [10]. Besides the knowledge of the material to be chosen for each case it is necessary to decide the treatment to know the severity and type of color change, how much time there is darkening, how many teeth will be involved in the treatment and how sensitive the patient is, these are criteria that influence the technique to be chosen [11]. These criteria are fundamental for treatment success without generating unrealistic expectations and consequent patient satisfaction [12,13].

Clinical protocol

An order to perform the whitening in the office it is imperative to protect the soft tissues, either by means of absolute isolation or by application of the light-curing gingival barrier, mouth opening and protection of the labial mucosa with (triamcinolona acetonida) thus avoiding burns and unpleasant sensations to the patient. After this phase of wellprotected protection makes the application of the peroxide chosen, be it carbamide or hydrogen, the dentist must control the time and the complete treatment [14,15].

Hydrogen peroxide is the bleaching agent most used in the bleaching of vital teeth, usually in the concentration of 35%. It has an immediate result, with a longer service time, but its cost may be higher. Hydrogen peroxide breaks down into free radicals breaking molecules, diffusing freely through the enamel and dentin structures, which are permeable facilitating the diffusion of oxygen to act on the pigmented structures of the teeth, brightening them [11,16,17].

Through a literary review, they evaluated the adverse effects of dental whitening [18]. The main agent being used hydrogen peroxide this review has shown that they have insignificant and reversible adverse effects, being a satisfactory and effective technique with correct clinical indication. Carbamide peroxide is a bleaching agent, which, in close contact with water present in the dentin tubules and saliva, degrades in hydrogen peroxide and urea [19]. 35% carbamide peroxide causes mild and moderate surface roughness of the enamel these effects were also found in 35% hydrogen peroxide [20]. Thus, clinically it is necessary that such agents be used with caution [21-23].

When thinking about gingival irritation and dentin sensitivity [24], in a clinical study, compared the effect of two bleaching agents both, hydrogen peroxide, but at different concentrations being 35% and 38% and found that there were no significant side effects and relapse of staining remained until the fifth week after that there was no significant change.

The use of halogen lamps tested to verify its effectiveness in the technique of bleaching in the office with hydrogen peroxide at 37.5% and there was no significant change in whitening [25].

Risks of bleaching treatment

Due to the controversy regarding the effects and risks of bleaching treatment, several researches being done to clarify possibilities such as safety, longevity, aggressions to soft and hard tissues, carcinogenic potential among other factors [26-29]. According to these studies, the sensitivity is the main problem reported regardless of the method used, even ceasing before the end of treatment [30].

Another factor investigated are the changes that occurred in enamel structures, such as possible dental bleaching problem, however, it was verified that the concentrations of Calcium and Phosphorus in the enamel did not present alterations when compared before, during and after the bleaching treatment both home and office [16].

Three 15-minute applications of hydrogen peroxide in one session are more efficient and promotes less sensitivity when compared to the 45-minute direct session. Due to the low pH of the bleaching agent, this may alter the micro hardness of the enamel, but after the removal of this agent and the contact of this enamel with the saliva this minimizes this adverse effect [31,32].

There are also inter-tubular changes and a reduction in the hardness values of the dentin surface due to the oxidative effects of hydrogen peroxide, besides the pH found in the agent [33].

Bleaching agent’s 35% hydrogen peroxide and 37% carbamide peroxide affected the surface roughness of nanohybrid and microhybrid composite resins [34]. The resins can also undergo changes, however easily eliminated with a good polishing [35].

In this way, we can affirm that dental bleaching, like any dental treatment, has risks, however, this much more related to wrong indication, abuse in use and incorrect application [36]. In research it was seen that dental sensitivity during and after the bleaching treatment affects 52% of the evaluated subjects, with 31% of this sensitivity being related to gingival irritation [37] or technical error in the placement of the gingival barrier or insulation. In addition, in the vast majority of these discomforts were mild or moderate and transient [38].

Adhesiveness

In study Cunha [19], the effect of hydrogen peroxide at 35%, in the bonding strength of adhesive systems based on acetone, alcohol and first auto conditions to dental enamel, in periods of time of 24 hours, 7 days and 14 days. Through the results obtained, the hydrogen peroxide at 35% did not alter the bonding strength of composite resin restorations to dental enamel, independent of the adhesive system used at the times tested.

However, this research redone after one year and the results showed different when there was a decrease in the efficacy of adhesive resistance to dentin when the adhesive used presented acetone as solvent, but the values of adhesive resistance to the dentin return to the values of the teeth not submitted to whitening in one week. The same bleaching technique did not alter the adhesive resistance to the dentin of the adhesive system that presents water and ethanol as solvent and for the self-etching adhesive system [39].

One year after in this study, a new in vitro study carried out to evaluate the adhesiveness of enamel composites after dental bleaching using 35% hydrogen peroxide and 37% carbamide peroxide, and demonstrated that the use of both bleaching gels causes reduction of adhesiveness [40]. However, the elements clarified with 37% carbamide peroxide recover the adhesion capacity more quickly and it would be feasible for dental surgeons to wait 48 hours to work safely regardless of the technique and material used. The waiting time of only 24 hours for accomplishment of adhesive restorative procedures has its adhesiveness compromised [41], more studies to clarify the controversies about the subject [42].

Clinical evaluation

The Visual scale and photos commonly used in the dental office to evaluate the color of the teeth for aesthetic procedures; this subjective form requires greater care, ranging from ambient illumination to operator training to minimize discordance. A form considered objective because it is less subject to variations achieved through a spectrophotometer, simple to use and with high precision [10], but not used in the daily routine of the clinician.

The offices usually have more than one source of light whether it is incandescent, fluorecent or natural, these cause differences in the color rendering by the visual mode, in addition to that the hygiene of the mouth must made in advance for better condition of choice [43].

The evaluations from time to time are important to determine the longevity of bleaching. However, the literature does not find work with a long-term follow-up of patients, which makes it difficult to obtain data to prove and guide its use [44]. All these conditions are of paramount importance for the correct independent clinical evaluation of the whitening agent, the technique employed.

Clinical research report

This study compared clinically the efficiency of two systems of whitening in the office, being a Hydrogen peroxide 35% and the other peroxide of Carbamide 37%. The application was done with the two bleaching agents in the same patient dividing the application in hemi arc for immediate clinical verification, after 7 days and after 5 months regarding the whitening power and the best visible result.

This study was performed at the dentistry clinic of the Centro Universitário do Norte Paulista of São José do Rio Preto (UNORP), in two patients, one with 23 years old and the other with 30 years old, siblings, both male, who found their teeth yellowish which bothered them a lot. In the anamnesis it was not reported by both patients, the exaggerated consumption of teas, coffees and affirmed that they were not smokers, did not report prolonged use of antibiotics, traumas and had no dental sensitivity.

After detailed anamnesis, clinical examination of the oral cavity carried out, in which complete health of soft tissues, vitality teeth, absence of carious lesions and few restorations. A form with identification (name, sex and age), treatment to be performed and signing of free and informed consent of both patients were completed.

Patients were advised about the proposed research and post-treatment care, such as diets and beverages containing dyes and in case of possible reports of sensitivity, the volunteers were separated for this study in patient A and patient B.

The dental arches molded with Hydrogum 5 (Zhermack), to obtain gypsum models for the preparation of individual 1 mm thick acetates, to complement with supervised bleaching to normalize the color of the arches after the bleaching in the office, in case there are differences between the arches. These trays tested for adaptations, soft tissue, and hard tissue relationships of both patients.

The whitened elements were of 2nd premolar right to the 2nd left premolar of both arches, divided into hemi-arches. For this, prophylaxis with pumice stone and water, with rubber cup and Robinson brush in all the elements, performed to remove the film acquired in the dental enamel. The labial retractor (Arcflex-FGM) continued the soft tissue protection and lip protection was applied to the base of triamcinolone acetonide.

Teeth coloring performed using the Vitapan Classical color scale where colors A 3,5 were selected for patient A (Figure 1) and A2 for patient B (Figure 2), digital photographs were taken for initial registration and then to compare the color of the teeth at the end of the bleaching treatment. For the sake of patient safety, the gingival barrier applied with TOP DAM to protect the gingival tissues and the papillae, with relative insulation with cotton rollers, keeping the teeth and tissues always dry so that there is no failure in the proposed technique.

Figure 1: Teeth coloring performed using the vitapan classical color scale.

Figure 2: Color of the teeth at the end of the bleaching treatment.

He office bleaching was performed with the bleaching agents 35% hydrogen peroxide and 37% carbamide peroxide, applied with the same technique, for this the patients' dental arches were divided in half with the placement of a polyester strip between the proximal ones central incisors to divide hemiarchs to start the bleaching technique (Figure 3). The right and left quadrants then given the corresponding whitening gel.

Figure 3: Bleaching technique.

The peroxide gel handled according to the manufacturer's recommendations (3 drops of peroxide to 1 thickener), handling until homogeneous. The hydrogen peroxide gel at 35% - Whiteness HP was applied with the aid of a plastic spatula applied in the upper and lower right hemispheres. The 37% carbamide peroxide (Office Power bleaching 37% -BM4) in the upper and lower left hemiarco, both at the same time. After 15 minutes, the products aspirated with the aid of a disposable surgical sucker and the gel re-applied according to the recommendations of the manufacturer of the product. Three applications were performed for 15 minutes, totaling 45 minutes.

After 45 minutes the gel removed by suction and gauze, the dental surfaces cleaned with dry cotton rollers and then rinsed with water/air spray. The gingival barrier removed with a scavenger probe, as well as the retractor. The colors registered shortly after the completion of the whitening agent (Figures 4 and 5).

Figure 4: Dental surfaces after the treatment.

Figure 5: Buccal aspects of the teeth.

After the procedure, patients A and B given the 16% carbamide peroxide based syringes and their previously made trays given a small drop of the product in the region of the tray corresponding to the buccal aspect of the teeth. Indicated the use of the bleaching product for 2 hours, during 30 days during the daytime period.

Results

The patients' age range was 23 and 30 years, therefore, older patients could present possible interferences due to the physiological alterations of the dental tissues as the largest deposition of reactive dentin. With regard to sensitivity, Table 1 shows that patients did not report sensitivity (0%) when using 37% Carbamide peroxide and 35% hydrogen peroxide. However, moderate sensitivity (100%) has been reported in patients using the 16% carbamide peroxide gel in the supervised home technique.

Table 1 Evaluation of the level of sensitivity by the substances.

Substances	Patient A	Patient B
Hydrogen Peroxide 35%	—	—
Carbamide Peroxide 37%	—	—
Carbamide Peroxide 16%	1	1

Regarding sensitivity, regarding whitening techniques (supervised or clinic), it is observed in Figure 6 that the sensitivity was higher in the supervised technique (100%).

Figure 6: Sensitivity assessment by bleaching techniques.

The color change was noted that there was no visible difference in the result obtained with hydrogen peroxide at 35% and carbamide peroxide at 37%, because if there was a decrease in the color scale of 1 to 3 shades, as illustrated in Table 2. As for the techniques, the office obtained the best result, since it managed to descend from 1 to 3 shades, in only one session while the supervised one kept the tones reached previously. There was no recurrence of color in reassessed patients.

Table 2 Evaluation of the change of tonality through the scores.

Substance	Patient N %	Score		Reduction of Tonality
		Initial	Finale
Hydrogen Peroxide 35%	A	3,5	1	2,5
	B	2	1	1
Carbamide Peroxide 37%	A	3,5	1	2,5
	B	2	1	1
Carbamide Peroxide16%	A	1	1	0
	B	1	1	0

Satisfaction was achieved in 100% of the patients, a very significant level. With greater emphasis on the office technique, there was no difference in satisfaction with the supervised one.

Discussion

There is a great deal of research on the topic of tooth whitening, but there is no similarity between the applied methodologies, which makes it difficult to compare different studies. In 2010, the researchers showed the greater effectiveness in the alteration of color in bleaching with the gel peroxide of hydrogen when compared with the carbamide [1].

However, when comparing the effects between the techniques of whitening used in the office and performed by the home technique, it was determined that both the technique in the office was more satisfactory than the home technique. However, after 14 days the techniques in question shown to be equivalent [45].

Based on these and other researches [46-48], it was proposed to investigate which clinic bleaching gel would be most effective clinically and in the eyes of the patient.

According to Nathoo et al. and Xavier et al. higher concentrations are able to clear more, confirming with the findings of this research. However, contrary to the results presented in this study, Dietschi et al. in their research, have highlighted the achievement of more significant results with the use of bleaching agents for domestic use, in the form of gels applied with the aid of when compared to the results obtained by the application of the photoactivated bleaching gels.

Simões emphasizes that the use of hydrogen peroxide in home bleaching achieves effective bleaching faster than carbamide peroxide, with equivalent proportions. This assertion is due to the fact that carbamide peroxide decomposes into hydrogen peroxide to be effective. However, in this work, P. carbamide was used 16% for a period of 4 weeks and an effective stabilization of the bleaching result of which can be observed in Table 2. Confirming the results of the present study, Ghassan et al. and Delfino et al. in their studies found that carbamide peroxide achieved a greater reduction of color than hydrogen peroxide in the same proportions and in the home technique. This fact can occur because carbamide peroxide produces urea which can still be decomposed into carbon dioxide and ammonia. High ammonia pH facilitates the bleaching procedure.

Any bleaching treatment tends to recur, so the procedure may require an additional visit. Although the results found in this research deny this fact, it is believed that with an evaluation for a longer period of time this may become a reality.

Patient satisfaction is very important, since the aesthetic appearance has influence in social life, work environment and mental health. Changes in the colors of the teeth are easily perceived causing enormous dissatisfaction to the patient. The satisfaction was achieved with the office technique and in higher values for the stabilization and maintenance of the color by the supervised technique. Confirming the findings of this research, Caballero et al. in their study, achieved satisfaction of the patients with the homemade technique.

Changes in the smile show admirable effects on people's self-esteem, especially in an extremely competitive society where the standard of beauty is so heavily ingrained by the current media, and certainly this pattern is tied to new perspectives.

The self-esteem of these boys improved with dental bleaching by 80%, thus confirming the importance of a beautiful smile for the individual's well-being, yet not enough for a high esteem.

It was found that the use of bleaching agents promotes a change in the color of the teeth, the degree of whitening being dependent on the technique used and the concentration of the chemical bleaching agents used. In this way, special care by the professionals, in the closing of the diagnosis, correct indication of the best technique and material that will be used.

Conclusion

Based on the results obtained, it can be concluded that:

1. Both techniques and substances are effective.

2. The office technique did not show sensitivity in 100% of the cases.

3. The supervised technique presented mild sensitivity in 100% of the cases.

4. The technique of surgery was that it presented greater color change, independent of the substance used, both P. Hydrogen 35% and Carbamide Peroxide 37%.

5. The technique that showed the highest percentage of patient satisfaction was in the office.

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