Teste Sensorial Quantitativo: efeito de um tratamento dessensibilizante após o clareamento dental.
QST após tratamento dessensibilizante
3.1 Resumo
O objetivo deste estudo clínico randomizado foi quantificar a sensibilidade dentária durante o tratamento clareador e após a aplicação de um dessensibilizante. Para tanto, o equipamento de análise neurosensorial, TSA II, foi utilizado para a realização do Teste Sensorial Quantitativo (QST) por meio de estímulos térmicos. Dez pacientes (n=10) receberam o tratamento clareador com peróxido de hidrogênio a 35% (Whiteness HP Maxx) e após a sessão clareadora foi realizada a aplicação de um dessensibilizante tópico a base de nitrato de potássio a 5% e fluoreto de sódio a 2% (Desensibilize KF 2%) apenas no hemi-arco esquerdo da maxila, utilizando o método da boca dividida. No hemi-arco direito foi aplicada uma solução salina a temperatura ambiente (controle). O QST foi realizado antes do clareamento (AC), imediatamente depois do clareamento (DC) e imediatamente após a aplicação do dessensibilizante (DD). Para padronizar o local do estímulo, uma moldeira de acetato com perfurações circulares foi utilizada durante as mensurações. A análise estatística foi realizada por meio do WHVWH W GH 6WXGHQW Į $V WHPSHUDWXUDV PpGLDV oC) (DP) do limiar de sensação ao frio para o hemi-arco direito (controle) foram: AC-13,898 (4,81), DC-19,241 (3,68), DD-20,646 (3,72) e para o hemi-arco esquerdo foram: AC-14,102 (3,22), DC-19,646 (4,82), DD-13,835 (3,63). Concluiu-se que clareamento dental com peróxidos de alta concentração exacerbaram a sensibilidade dental ao estímulo térmico e que o uso do dessensibilizante foi efetivo para reverter esta situação.
Perspectiva: O novo método utilizado neste estudo pode aumentar a confiabilidade dos
estudos clínicos sobre sensibilidade dentária ao analisar quantitativamente a eficácia de tratamentos dessensibilizantes após o clareamento dental. Esta análise neurosensorial pode ajudar no desenvolvimento de terapias clareadoras mais seguras e confortáveis.
Palavras-chave: Ensaio Clínico. Peróxido de Hidrogênio. Clareamento Dental. Sensação. Análise Quantitativa.
Quantitative Sensory Testing of the effect of desensitizing treatment after dental bleaching
QST assessment after desensitizing treatment
3.2 Abstract
The aim of this randomized clinical trial was to quantify dental sensitivity during bleaching treatment and before a desensitizing treatment using a new device, TSA II, that uses thermal stimuli to conduct Quantitative Sensory Testing (QST). Ten patients (n=10) underwent bleaching treatment using 35% hydrogen peroxide (Whiteness HP Maxx). After the bleaching session, the teeth were cleaned with air/water spray and the split-mouth design was used. Thus, a topical desensitizer containing 5% potassium nitrate and 2% sodium fluoride (Desensibilize KF 2%) was applied to the teeth of the left maxillary hemi-arch. A saline solution at ambient temperature was applied in the right maxillary hemi-arch (control). QST was performed before bleaching (BB), immediately after bleaching (AB), and immediately after the desensitizer (AD). For standardization of tooth analysis, an acetate tray, with circular SHUIRUDWLRQV ZDV XVHG 6WXGHQW¶V W-test was XVHG Į WR DQDO\]H WKH GDWD 0HDQ temperatures (oC) (SD) of cold sensation threshold for the right hemi-arch (control) were: BB- 13.898 (4.81), AB-19.241 (3.68), AD-20.646 (3.72) and for the left hemi-arch were: BB- 14.102 (3.22), AB-19.646 (4.82), AD-13.835 (3.63). Dental bleaching with highly concentrated peroxides increased dental cold sensation thresholds, but the topical desensitizer reversed the immediate cold sensation caused by the cold stimulus.
Perspective: The new method used in this study may increase the reliability of clinical
studies regarding dental sensitivity and quantitatively assess the effect of a desensitizing treatment after dental bleaching. This neurosensory analysis could potentially help to develop safer and more comfortable bleaching therapies.
Keywords: Clinical Trial. Hydrogen peroxide. Dental Bleaching. Sensation. Quantitative
3.3 I ntroduction§
Dental professionals often consider dental bleaching to be a conservative technique that provides low-cost, effective, and fast results. As many patients request dental bleaching, it has become a primary marketing and a focus of treatment planning for many dental professionals.1,16,33,38 When supervised by a dentist, home bleaching can be a simple, safe, and esthetically pleasant approach.15,16,28,38 However, the in-office technique that uses highly concentrated hydrogen peroxide has been widely used because results are achieved quickly without the use of trays.6,12,17
Usually, dental professionals apply products containing 30% to 40% hydrogen peroxide while protecting soft tissues against deleterious effects.14,16 Bleaching occurs using an unstable type of reactive oxygen that oxidizes tooth pigments, promoting lightening.16,42 Despite the effectiveness of dental bleaching, current studies reveal that patients exposed to this whitening strategy report different frequency and intensity of dental sensitivity,28,14 a negative treatment outcome that UHGXFHVSDWLHQW¶VVDWLVIDFWLRQ
The current literature does not clarify the origin of dental sensitivity, which is crucial in determining an effective bleaching technique that causes minimum patient discomfort. In the past, desensitizers have been applied to reduce discomfort with no apparent influence on bleaching efficacy. 20,33,46,48 Among many different options, 5% potassium nitrate, which may or may not be incorporated with 2% sodium fluoride, has been used as a desensitizing agent.25,37,46,48
Clinical studies have evaluated the frequency and intensity of dental sensitivity and have presented subjective data based on personal reports6,5,28,34 and pain questionnaires5 according to the Visual Analogue Scale (VAS). However, misunderstanding of data may have
§
affected the reliability and reproducibility of results, leading to the search for a more reliable quantification method of patient discomfort concomitant with the dental bleaching process. Currently, certain devices allow quantification of neurosensory response related to major and minor nervous fibers47 through Quantitative Sensory Testing (QST) using thermal, mechanical, or electrical stimuli.22,23,27,32,39,41 Because the QST is a fast and useful method resulting from standardized and accurate analysis,23,27,32 it is used in several fields, including anesthesiology,39 acupuncture,27 endocrinology,24,36 neurology,8,11,30 and dermatology.40 In dentistry, it was initially employed to quantify maxillofacial surgery and orofacial pain2,22,23,41 for evaluation of neurological responses after third molar exodontia and orthognathic surgery. However, research has so far not focused on the use of QST to evaluate dental sensitivity. Thus, quantitative testing for cold sensation thresholds may improve the accuracy of studies on dental sensitivity that is frequently reported with dental bleaching.
The TSA II (Medoc Advanced Medical Systems Ltd., Ramat Yishai, Israel)19,27,29,39,42 allows the quantification of sensations and performs testing for cold and hot sensation thresholds using a thermode that is cooled and heated at different times and at different temperatures.23,19
The aim of the present study was to use the neurosensory analysis to quantify thermal dental sensitivity before and after dental bleaching and to compare patient cold sensations both using and not using desensitization methods. More accurate knowledge of patient symptomology in the dental bleaching process may help the development of safe and comfortable bleaching therapies.
As a null hypothesis, it was assumed that:
- dental bleaching with highly concentrated peroxides would not influence cold sensation thresholds and
- the use of topical desensitizer containing sodium fluoride and potassium nitrate would not change the immediate cold sensation thresholds provoked by a specific cold stimulus.
3.4 M aterials and M ethods
After approval by the Committee of Ethics in Research (00278/2011), 10 patients aged from 18 to 25 years were selected according to the criteria shown in Table 1. After the informed consent was obtained from each subject, the patients were carefully evaluated and submitted to anamnesis and appropriate clinical and radiographic exams before allocation (Figure 1).
This present study is a factorial and blinded clinical trial with equal randomization and included the factors: (1) desensitizing treatment in 2 levels (5% potassium nitrate associated with 2% sodium fluoride or saline) and (2) 3 periods of evaluation: before bleaching (BB), immediately after bleaching (AB), and immediately after desensitizing (AD). Dental sensitivity to thermal stimuli was evaluated, and the split-mouth design method was used. Thus, maxillary arch was divided into right and left hemi-arches depending on the desensitizing treatment (n=10) (Table 2).
Quantitative Sensory Testing (QST)
Quantitative Sensory Testing (QST) for cold sensation thresholds was conducted during the first bleaching session from right maxillary canine to left maxillary canine. The evaluation was performed in the following sequence: right maxillary canine, left maxillary canine, right maxillary lateral incisor, left maxillary lateral incisor, right maxillary central incisor, and left maxillary central incisor. Analyses were conducted before bleaching (BB), immediately after bleaching (AB), and immediately after application of desensitizer or not (AD).
For standardization of tooth analysis, a 100% ethylene copolymer and vinyl acetate tray was fabricated for each patient. The tray had circular perforations with a diameter similar to the active tip of the intraoral thermode. The perforations were created on the buccal surface
and 2 mm below the cervical, incisal, and proximal margins of the maxillary teeth, except the canine position, which was perforated 3 mm below the distal margin.
Before measurement, each tooth was covered with 0.05 ml of thermal conductive paste containing silver oxide (IPT - Pasta Térmica Implastec, Implastec Eletroquímica Ltd., Votorantim, São Paulo, Brazil) to optimize thermal conduction. The tests were performed in a dental clinic in a silent environment with a constant temperature of 26º C. The sessions were conducted from 8:00 a.m. to 10:00 a.m.
The neurosensory analyzer TSA II (Medoc TSA II Neurosensory Analyzer, Ramat Yishai, Israel) was used for the testing of cold sensation thresholds employing CST. TSA II consists of a central unity for the generation of thermal signs that is controlled by software and connected to another device held by the patient. The patient is able to stop cooling of the intraoral thermode at any time (Figure 2).
7KH 76$ ,, ZDV FRQILJXUHG XVLQJ WKH ³/LPLWV´ IXQFtion, and three descending temperature tests were performed on each tooth. The test began at 36o C, and the thermode cooling speed was 0.5º C per second, resulting in slow temperature variation that allowed even transference of the thermal stimulus to the dentine-pulp complex. After patient perception of temperature alteration, the patient paused the stimulus, and the measurement was repeated for two times, 30 seconds after the previous one.
The values obtained during the first test were discarded, and the mean of the following tests was used as the initial temperature for cold sensation threshold testing in each tooth. Subsequently, the cold sensation thresholds for all teeth from the same hemi-arch were grouped for comparison between treatments.
Bleaching Treatment
The in-office bleaching technique used 35% hydrogen peroxide (Whiteness HP Maxx, FGM Produtos Odontológicos ± Ltda., Joinville, Santa Catarina, Brazil) (Table 3) and no physical activation. The product is commercially available as a two-bottle system (one bottle contains the peroxide and the other contains the activator, and the substances are mixed in a peroxide/activator ratio of 3:1 drops.
After tooth prophylaxis and soft tissue isolation using a light cured resin gingival barrier (Top Dam ± FGM Produtos Odontológicos Ltda., Joinville, Santa Catarina, Brazil), the bleaching agent was inserted into a graduated syringe, and 0.06 ml of the bleaching product was applied on the buccal surface of the teeth for 15 minutes. After the first application, the teeth were cleaned and dried with gauze, and the procedure was repeated twice, totalizing 45 minutes of contact between the bleaching product and enamel.
Desensitizing Treatment
After the bleaching session and immediately after the second cold sensation measurement, the teeth were cleaned with an air/water spray and 5% potassium nitrate with 2% sodium fluoride (Desensibilize KF 2%, FGM Produtos Odontológicos Ltda., Joinville, Santa Catarina, Brazil) (Table 3) was applied to the teeth of the left maxillary hemi-arch, DFFRUGLQJWRWKHPDQXIDFWXUHU¶VLQVWUXFWLRQV,QWKHULJKWKHPL-arch, saline at environmental temperature was applied in the same way previously described. After 10 minutes, the tooth surfaces were washed thoroughly.
Statistical Analysis
The mean values obtained were grouped according to the period of evaluation: before bleaching (BB), after bleaching (AB), and after application or non-application of desensitizer
(AD). Data concerning each hemi-DUFK ZDV VXEPLWWHG WR 6WXGHQW¶V W-test at a 5% level of significance using Pacotico 5.1 statistics software.
3.5 Results
Table 4 shows the mean temperature of cold sensation thresholds in each hemi-arch. In the periods BB and AB, there was no statistically significant difference between the hemi- arches. However, in period AD, a significant difference (p =0.0000) was observed between the right and left hemi-arches.
In the hemi-arches, dental bleaching increased the mean values of cold sensation thresholds, which means that the teeth became more sensitive. In the right hemi-arch, dental cold sensation after bleaching stayed the same after use of saline solution. However, in the left hemi-arch, the values measured at AD were similar to the initial values obtained at BB
(p = 0.7645). Overall, results revealed a reduction of dental sensitivity after desensitizing application (Figure 3).
3.6 Discussion
Quantitative Sensory Testing (QST): Advantages and Limitations of the Method
Different results in dental sensitivity show that sensory function is not consistent and uniform, so reliable and reproducible methods should be applied.18 In this sense, the development of an accurate pain-testing methodology is helpful for the evaluation of dental sensitivity and for indicating proper treatments.
Quantitative Sensory Testing (QST), widely used in skin and oral mucosa, was adapted to the present study for testing of cold sensation thresholds on tooth surfaces. %HFDXVH467UHTXLUHVSDWLHQWV¶FROODERUDWLRQWRVWRSWKHWKHUPDOVWLPXOXVLPmediately after its perception,9,47 the test must be conducted in a silent environment with a constant temperature. In addition, test reliability depends on the control group. In the present study, the control was characterized by use of saline as a desensitizer in the right hemi-arch.21,22
The configuration of the TSA II should be carefully predetermined to avoid any influence of repetition on tests of the same tooth. An interval between tests was crucial to achieve 36 oC, a temperature comfortable for patients and to avoid the unwanted aggregation of stimuli. Similarly, cooling speed was relevant in the transference of thermal stimuli to the dentine-pulp complex.
Bleaching and Desensitizing Treatments
The high concentrations of hydrogen peroxide44 and the pH of the bleaching products have been associated with histomorphological alterations in enamel, the increase of enamel permeability, and the penetration of byproducts generated by the decomposition of bleaching agents.3,10 These phenomena are related to a high frequency of dental sensitivity, which is considered the most common side effect of dental bleaching.13,26
The physiology of dental sensitivity after bleaching remains unclear due to the functional and structural complexity of teeth, including nervous, odontoblastic, and internal movement of fluids.27,29,31,35,39,42 The hydrodynamic theory4 is based on the movement of dentin fluid as the result of several stimuli that excite the pulp nervous fibers and cause pain.7,31 The excessive oxygen generated by bleaching products in the pulp also stimulates the release of inflammatory chemical mediators, such as substance P, that sensitize the pulp nociceptors and play a role in pain modulation38,45 a fact that can be observed in the values of cold sensation thresholds near patienWV¶FRPIRUWDEOHWHPSHUDWXUH oC).
However, the presence of surface alterations on teeth suggests that the topical action of some products may reverse those alterations or treat dental sensitivity. The positive response to desensitizing after dental bleaching is in accordance with the results of studies by Tay et al.48 and Reis et al.45 that demonstrate the effectiveness of 5% potassium nitrate used with 2% sodium fluoride. It may be due to the neurological action of potassium nitrate that disturbs the depolarization of neurons and reduces the effectiveness of sensory nervous conduction.43,45,48 Hemi-arches treated with this desensitizing agent exhibited lower temperatures of cold sensation thresholds than the hemi-arches treated with saline. In addition, the formation of calcium fluoride on flaws, diffusion channels, and gaps in the dentine-pulp complex represented a physical barrier with this desensitizer.45 Thus, the null hypothesis was rejected because similar data were obtained at the periods BB and AD in the left maxillary hemi-arch treated with desensitizer.
Considering the data of the present study and previous results related to desensitizing effectiveness,45,48 the quantitative analysis of dental sensitivity using a neurosensory method is a promising approach for further clinical studies of this symptom caused by several dental treatments.
3.7 Conclusion
- Dental bleaching with highly concentrated peroxides increased dental cold sensation thresholds.
- Topical desensitizer containing sodium fluoride and potassium nitrate reversed the immediate cold sensation thresholds provoked by the cold stimulus.
3.8 Acknowledgements
This research was supported by Fapesp (10/11627-6). The authors thank FGM Produtos Odontológicos Ltda for providing the bleaching materials.
Moreover, the research is free of conflict of interest and it was conducted by the highest principles of human subject.
3.9 References* *
1. Auschill TM, Hellwig E, Schmidale S, Sculean A, Arweiler NB: Efficacy, side effects and patients´ acceptance of different bleaching techniques (OTC, in-office, at-home). Oper Dent 30:156-163, 2005.
2. Baad-Hansen L, Arima T, Arendt-Nielsen B, Neumann-Jensen B, Svensson P: Quantitative sensory tests before and 1 » \HDUVDIWHURUWKRJQDWKLFVXUJHU\ DFURVV- sectional study. J Oral Rehabil 37:313-321, 2010.
3. Bistey T, Nagy IP, Simó A, Hegedus C: In vitro FT-IR study of the effects of hydrogen peroxide on superficial tooth enamel. J Dent 35:325-330, 2007.
4. Brännström M, Aström A: The hydrodynamics of the dentine; its possible relationship to dentinal pain. Int Dent J 22:219±227, 1972.
5. Browning WD, Blalock JS, Frazier KB, Downey MC, Myers ML: Duration and timing of sensitivity related to bleaching. J Esthet Restor Dent 19:256-264, 2007. 6. Callan RS, Browning WD, Downey MC, Brackett MG: Comparison of two low
sensitivity whiteners. AmJ Dent 21:17-20, 2008.
7. Charakorn P, Cabanilla LL, Wagner WC, Foong WC, Shaheen J, Pregitzer R, Schneider D: The effect of preoperative ibuprofen on tooth sensitivity caused by in- office bleaching. Oper Dent 34:131-135, 2009.
8. &KpOLRXW-+pUDXW) , Zrek N, Khemliche H, Varnet O, Seret-Begue D, Martinez M, Nizou R, Bour F: Exploration of small fibers for testing diabetic neuropathies. Joint Bone Spine 72:412-415, 2005.
9. Chong PS, Cros DP: Technology literature review: quantitative sensory testing. Muscle Nerve 29:734-747, 2004.
10. Cooper JS, Bokmeyer TJ, Bowles WH: Penetration of the pulp chamber by carbamide peroxide bleaching agents. J Endod 18:315-317, 1992.
11. Cruccu G, Sommer C, Anand P, Attal N, Baron R, Garcia-Larrea L, Haanpaa M, Jensen TS, Serra J, Treede RD: EFNS guidelines on neuropathic pain assessment: revised 2009. Eur J Neurol 17:1010-1018, 2010.
12. Da Silva Marques DN, Silveira JM, Marques JR, Amaral JA, Guilherme NM, da Mata AD: Kinetic release of hydrogen peroxide from different whitening products. Eur J Esthet Dentistry 7:344-352, 2012.
**
Referências identificadas no texto em números arábicos sobrescritos e numeradas de acordo com a ordem alfabética do sobrenome do primeiro autor (Anexo C).
13. Dawson PF, Sharif MO, Smith AB, Brunton PA: A clinical study comparing the efficacy and sensitivity of home vs combined whitening. Oper Dent 36:460-466, 2011. 14. Delfino CS, Chinelatti MA, Carrasco-Guerisoli LD, Batista AR, Fröner IC, Palma-
Dibb RG: Effectiveness of home bleaching agents in dicolored teeth and influence on enamel microhardness. J Appl Oral Sci 17:284-288, 2009.
15. Dietschi D: Bright and white: is it always right? J Esthet Restor Dent 17:183-190, 2005.
16. Dietschi D, Rossier S, Krejci I: In vitro colorimetric evaluation of the efficacy of various bleaching methods and products. Quintessence Int 37:515-526, 2006.
17. Dos Santos Medeiros MC, de Lima KC: Effectiveness of nigthguard vital bleaching with 10% carbamide peroxide ± a clinical study. J Can Dent Assoc 74:163-163e, 2008. 18. Dyck PJ, Zimmerman I, Gillen DA, Johnson D, Karnes JL, 2¶%ULHQ3&: Cool, warm, and heat-pain detection thresholds: testing methods and inferences about anatomic distribution of receptors. Neurology 43:1500-1508, 1993.
19. Granot M, Nagler RM: Association between regional idiopathic neuropathy and salivary involvement as the possible mechanism for oral sensory complaints. J Pain 6:581-587, 2005.
20. Hannig C, Weinhold HC, Becker K, Attin T: Diffusion of peroxides through dentine in vitro with and without prior use of a desensitizing varnish. Clin Oral Investig 15:863-868, 2011.
21. Juhl GI, Jensen TS, Norholt SE, Svensson P: Central sensitization phenomena after third molar surgery: a quantitative sensory testing study. Eur J Pain 12: 116-127, 2008. 22. Juhl GI, Svensson P, Norholt SE, Jensen TS: Long-lasting mechanical sensitization
following third molar surgery. J Orofac Pain 20:59-73, 2006.
23. Kalantzis A, Robinson PP, Loescher AR: Effects of capsaicin and menthol on oral thermal sensory thresholds. Arch Oral Biol. 52:149-153, 2007.
24. Kalter-Leibovici O, Yosipovitch G, Gabbay U, Yarnitsky D, Karp M: Factor analysis of thermal and vibration thresholds in young patients with Type 1 diabetes mellitus. Diabet Med 18:213-217, 2001.
25. Kose C, Reis A, Baratieri LN, Loguercio AD: Clinical effects of at-home bleaching along with desensitizing agent application. Am J Dent 24:379-382, 2011.
26. Krause F, Jepsen S, Braun A: Subjective intensities of pain and contentment with treatment outcomes during tray bleaching of vital teeth employing different carbamide