At home vital teeth bleaching: how to optimize a safe and stable result

Dental News Magazine – January 2021 Issue

Neila Zokkar (neila_zokkar@yahoo.fr) – Professor, Department of Restorative Dentistry-Endodontics, Faculty of Dental Medicine, Monastir, Tunisia

Marwen Ouni – Post graduate Student, Department of Restorative Dentistry-Endodontics, Faculty of Dental Medicine, Monastir, Tunisia

Hana Serrag – Post graduate Student, Department of Restorative Dentistry-Endodontics, Faculty of Dental Medicine, Monastir, Tunisia

Emna Hidoussi – Assistant Professor, Department of Restorative Dentistry-Endodontics, Faculty of Dental Medicine, Monastir, Tunisia

Abstract

Faced with the evolution of modern society which attaches great importance to aesthetics and appearance, as well as the media coverage of the criteria of the «beautiful smile», the demand to have «white teeth» has increased in recent years.

Over time, various strategies have been used to recover the natural color of the tooth, one of which, vital teeth bleaching is the most effective and cautious treatment procedure. Several whitening systems have been described that can be split into two different categories: in-office and at-home whitening systems.

The present article aims to address, through a case report, the interests of at home technique in the treatment of extrinsic teeth dyschromia and to discuss the side effects of this treatment, as well as the precautions to be taken to avoid these undesirable effects and to ensure the stability of the outcome over time.

Keywords: tooth whitening, home whitening, smile, dyschromia, stability of the result, carbamide peroxide, mechanism of tooth sensitivity

Introduction 

«The smile is an element of unconscious expression and communication, like touch», underlines Bernard Andrieu, body philosopher. Faced with the evolution of modern society which attaches great importance to aesthetics and appearance, as well as the media coverage of the criteria of the «beautiful smile», the demand to have «white teeth» has increased in recent years.  

The growing desire for a better look and a whiter smile has made tooth whitening as a common dental treatment. It has grown into one of the fastest developing fields of esthetic dentistry, providing a more conservative treatment approach for discolored teeth compared to other restorative methods ¹. 

The aim of this paper was to address, through a case report, the interests of at home technique in the treatment of extrinsic teeth dyschromia and to discuss the side effects of this treatment, as well as the precautions to be taken to avoid these undesirable effects and to ensure the stability of the outcome over time.

Case report

A 25-year-old patient in good general health condition consults for dyschromia. The intra-oral examination shows good oral hygiene. The dyschromia is of extrinsic origin, this led us to the ambulatory bleaching technique which is the safest technique for this type of dyschromia. Pre-operative photos are taken (Figure 1). The patient’s initial shade is an A3,5.

The first session is devoted to discussing the necessary precautions, after signing the informed consent. Then we took impressions in order to make compressive aligners.

The choice was towards a whitening gel with a low concentration of hydrogen peroxide (16% of carbamide peroxide): Mix Night 16%. 

Then, dental scaling has been performed. The patient will be checked every week with photos taken.

In order to give the patient a basis for comparison; we started with the whitening of the upper arch (Figure 2+3).

The lower arch is taken care of after 3 weeks from the start of whitening of the upper arch (figure 4).

During the treatment of the lower arch, moderate tenderness was felt by the patient; so, our attitude was oriented towards treatment with a desensitizing gel by wearing trays filled with this gel 10 minutes before the whitening procedure begins; which made it easier for the patient to complete the lower arch whitening procedure (figure 5+6). 

In order to have a homogeneous result, we ended with a week of bleaching two arches (figure 7).

And for the stabilization of the result obtained, a week of treatment is scheduled after four months (Figures8+9). This procedure will be repeated every four months for two years.

Discussion

Over time, several whitening systems have been described that can be split into two different categories: in-office and at-home whitening systems. 

According to the literature, there were many side effects reported with ‘in-office whitening systems’, such as the high cost, the long chair time, and the regular occurrence of unintended effects on soft and hard oral tissues. ²
On the other hand, at home whitening systems are commercially available, and easy to use. 

The vast number of bleaching gels and protocols tested by randomized controlled trials prohibit clinicians from concluding explicitly which protocol has an improved whitening effect.  Some studies assume that at-home bleaching is safer and more stable than in-office protocol². Others showed that for both methods, the effects were equivalent instantly and at long-term ^{4, 5}.

Similar controversy exists in terms of teeth sensitivity. Some authors have shown that in-office bleaching occurs a higher tooth sensitivity than at-home protocol, whereas other studies report similar tooth sensitivity ^{6, 7} or even higher tooth sensitivity of the at home procedure than the in-office protocol.⁸

The mechanism of tooth sensitivity caused by bleaching agents is not well known currently.

Researchers have speculated that initial diffusion of peroxide into the pulp chamber through enamel and dentine can contribute to pulp inflammation and nerve activity ⁹. Other investigators have hypothesized that bleaching agents could release cellular factors such as ATP and prostaglandins which could excite or disrupt the pulp tissues ¹⁰. Another theory which is currently not well known is the hydrodynamics of intradental nerve stimulation and neuropeptide release in response to this treatment ¹¹. Also, Glycerin, contained in most bleaching agents as a carrier, is hydrophilic which causes dehydration of tooth structure during bleaching treatment. This can contribute to tooth sensitivity as well ¹². 

According to the literature, it affects between 37% and 90% of patients with at-home bleaching and between 16.7% and 100% of patients with in-office bleaching ^{13, 14}. The major part of patients report mild sensitivity while 10% experience moderate and only 4% may experience severe sensitivity ¹⁵.

Symptoms are observed at an early stage of the therapy, usually after 2-3 days, and can continue for 3-4 hours after tray removal. ¹⁶

In the case of at-home bleaching, the occurrence of hypersensitivity increases with the frequency of changes in bleaching solution, particularly if they are changed more than once a day  ¹². 

The bleaching intervals should be reduced for the better rapid result. Modifications and improvements to bleaching products have also been made. Potassium nitrate and sodium fluoride as desensitizers are commonly used. These agents can be stored in bleaching gel and administered during treatment using a personalized tray. The precise mechanism of action of potassium nitrate and sodium fluoride to minimize tooth sensitivity in the tooth whitening process is not well known ¹⁷. 

Potassium ions are likely to be an active component reducing dentinal sensory nerve activity due to K+ depolarizing activity ¹⁸. 

Fluoride, on the other hand, treats dentinal sensitivity likely by covering exposed dentinal tubules or reducing fluid flow to the pulp and covering the transfer of stimuli. Different modes of distribution of desensitizing agents were reported in the literature. Some authors have added desensitizing gel to the teeth buccal surface without disrupting it for ten minutes ¹⁰. Others, used desensitizing agents as adjuvants to the bleaching gel ¹⁹. 

However, according to a meta analysis study conducted by Costacurta et al. in March 2020 ²⁰; the addition of potassium nitrate to carbamide peroxide gel did not reduce the risk and intensity of tooth sensitivity during at-home bleaching. Generally, patients with cracked tooth syndrome or with tooth sensitivity should be warned.

Gingival and mucosal irritations are another side effect of home whitening technique. Commonly, an ill-fitting tray that affects the gingiva and/or the use of excessive material may cause soft tissue inflammation. Management requires simple adjustment and polishing of the tray and or instructing the patient to use less material ¹⁶. 

Concerning the systemic effects, patients rarely report gastrointestinal or mucosal irritations, like burning palate and throat burning, and mild stomach or intestines upsets. ²¹ In this context, several literature studies suggest that the use of low hydrogen peroxide concentrations in tooth bleaching is still safe ²².

Concerning side effects on dental hard tissues, contradictions are reported in the available literature. Some electron microscopic scanning studies recorded changes in the enamel surface morphology after application of carbamide peroxide or hydrogen peroxide; with increased enamel structure porosity, demineralization, lower protein concentration, organic matrix degradation, and calcium-phosphate-ratios alteration ²³. 

While others reported no changes in the morphology of the enamel ²⁴. Sulieman et al. reported that 35% hydrogen peroxide did not damage enamel or dentine, and that the pH of the products used can have the adverse effects listed in the literature ²⁵.

Many authors recommend the addition of calcium and fluoride in bleaching agents to reduce enamel demineralization. However, according to Cavalli et al.’ study; even though experimental bleaching agents with calcium or fluoride reduced mineral loss, these agents were unable to reverse the enamel subsurface demineralization ²⁶. 

According to Darriba et al. ²⁷, daytime application of at-home bleaching for 3 weeks achieves greater bleaching results than for 2 weeks, immediately after treatment, one and 6 months afterwards. Another randomized trial ²⁸ showed that at-home bleaching is time but not concentration dependent and its secondary effects depend on the active agent concentration; therefore, there is no need to use high concentration products. According to this study, the most effective protocol is low concentrations (10% carbamide peroxide) with longer time application (overnight use for three weeks are recommended).

Conclusion

Clinicians should warn their patients of the benefits and potential side effects of teeth whitening. Higher concentrations of peroxide may improve the whitening result and minimize the length of application, although side effects like tooth sensitivity, and tooth hard tissues changes may also be increased with this form of procedures. However, higher concentrations of the bleaching agent than recommended could more likely cause damage to the gingival and dental tissues ²⁹.

At-home external bleaching did not demonstrate significant long-term complications if 10% carbamide peroxide was used as the bleaching agent. The whitening treatments have been continually improved until now. The latest methods for reducing the disconfort associated with these whitening procedures are not, according to recent clinical reports, entirely successful and also need to be refined ^{30, 31}.

It is still important to build a more powerful, reliable, and long-lasting therapy to achieve an optimal effect of whitening without any damage.

References

1. Farooq, I., Tooth-Bleaching: A Review of the Efficacy and Adverse Effects of Various Tooth Whitening Products. Journal of the College of Physicians and Surgeons–Pakistan: JCPSP, 2015. 25.

2. Parreiras, S., et al., Effects of Light Activated In-office Bleaching on Permeability, Microhardness, and Mineral Content of Enamel. Operative Dentistry, 2014. 39(5): p. E225-E230.

3. Matis, B.A., et al., Eight in-office tooth whitening systems evaluated in vivo: a pilot study. Oper Dent, 2007. 32(4): p. 322-7.

4. Tay, L.Y., et al., Long-term efficacy of in-office and at-home bleaching: A 2-year double-blind randomized clinical trial. American journal of dentistry, 2012. 25: p. 199-204.

5. Giachetti, L., et al., A randomized clinical trial comparing at-home and in-office tooth whitening techniques: A nine-month follow-up. J Am Dent Assoc, 2010. 141(11): p. 1357-64.

6. Zekonis, R., et al., Clinical evaluation of in-office and at-home bleaching treatments. Oper Dent, 2003. 28(2): p. 114-21.

7. Moghadam, F.V., et al., The degree of color change, rebound effect and sensitivity of bleached teeth associated with at-home and power bleaching techniques: A randomized clinical trial. Eur J Dent, 2013. 7(4): p. 405-411.

8. Basting, R.T., et al., Clinical comparative study of the effectiveness of and tooth sensitivity to 10% and 20% carbamide peroxide home-use and 35% and 38% hydrogen peroxide in-office bleaching materials containing desensitizing agents. Oper Dent, 2012. 37(5): p. 464-73.

9. Kim, S., Neurovascular interactions in the dental pulp in health and inflammation. J Endod, 1990. 16(2): p. 48-53.

10. Reis, A., et al., Assessment of Tooth Sensitivity Using a Desensitizer Before Light-activated Bleaching. Operative Dentistry, 2011. 36(1): p. 12-17.

11. Markowitz, K., Pretty painful: why does tooth bleaching hurt? Med Hypotheses, 2010. 74(5): p. 835-40.

12. Leonard, R.H., Jr., V.B. Haywood, and C. Phillips, Risk factors for developing tooth sensitivity and gingival irritation associated with nightguard vital bleaching. Quintessence Int, 1997. 28(8): p. 527-34.

13. de Paula, E.A., et al., In-office bleaching with a two- and seven-day intervals between clinical sessions: A randomized clinical trial on tooth sensitivity. Journal of dentistry, 2015. 43(4): p. 424-429.

14. Bonafé, E., et al., Tooth sensitivity and efficacy of in-office bleaching in restored teeth. J Dent, 2013. 41(4): p. 363-9.

15. Jorgensen, M. and W. Carroll, Incidence of tooth sensitivity after home whitening treatment. Journal of the American Dental Association (1939), 2002. 133: p. 1076-82; quiz 1094.

16. Sulieman, M., An Overview of Bleaching Techniques: 2. Night Guard Vital Bleaching and Non-Vital Bleaching. Dental Update, 2005. 32(1): p. 39-46.

17. Wang, Y., et al., Evaluation of the efficacy of potassium nitrate and sodium fluoride as desensitizing agents during tooth bleaching treatment—A systematic review and meta-analysis. Journal of Dentistry, 2015. 43(8): p. 913-923.

18. Fugaro, J.O., et al., Pulp reaction to vital bleaching. Oper Dent, 2004. 29(4): p. 363-8.

19. Navarra, C.O., et al., The effects of two 10% carbamide peroxide nightguard bleaching agents, with and without desensitizer, on enamel and sensitivity: an in vivo study. Int J Dent Hyg, 2014. 12(2): p. 115-20.

20. Costacurta, A.O., et al., Does the addition of potassium nitrate to carbamide peroxide gel reduce sensitivity during at-home bleaching? Aust Dent J, 2020. 65(1): p. 70-82.

21. POHJOLA, R.M., et al., Sensitivity and Tooth Whitening Agents. Journal of Esthetic and Restorative Dentistry, 2002. 14(2): p. 85-91.

22. Alqahtani, M.Q., Tooth-bleaching procedures and their controversial effects: A literature review. The Saudi dental journal, 2014. 26(2): p. 33-46.

23. Pinto, C.F., et al., Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology. Braz Oral Res, 2004. 18(4): p. 306-11.

24. Haywood, V.B., et al., Nightguard vital bleaching: effects on enamel surface texture and diffusion. Quintessence Int, 1990. 21(10): p. 801-4.

25. Sulieman, M., et al., A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine. J Dent, 2004. 32(7): p. 581-90.

26. Cavalli, V., et al., Effects of experimental bleaching agents on the mineral content of sound and demineralized enamels. J Appl Oral Sci, 2018. 26: p. e20170589.

27. I, L.D., et al., Influence of treatment duration on the efficacy of at-home bleaching with daytime application: a randomized clinical trial. Clin Oral Investig, 2019. 23(8): p. 3229-3237.

28. López Darriba, I., L. Novoa, and V.A. de la Peña, Efficacy of different protocols for at-home bleaching: A randomized clinical trial. Am J Dent, 2017. 30(6): p. 329-334.

29. Pintado-Palomino, K., et al., A clinical, randomized, controlled study on the use of desensitizing agents during tooth bleaching. J Dent, 2015. 43(9): p. 1099-1105.

30. Rezende, M., et al., Tooth Sensitivity After Dental Bleaching With a Desensitizer-containing and a Desensitizer-free Bleaching Gel: A Systematic Review and Meta-analysis. Oper Dent, 2019. 44(2): p. E58-e74.

31. Vaez, S.C., et al., Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial. J Appl Oral Sci, 2018. 26: p. e20160473.

You can find this article here: Dental News Magazine – January 2021 Issue