INTRODUCTION
The most commonly observed staining of vital teeth is the result of highly colored drink or food. Tobacco produces a yellowish brown to black discoloration, usually in the cervical portion of the teeth and mainly on the lingual surfaces. Chewing tobacco frequently penetrates the enamel to produce an even darker stain, and marijuana may produce sharply delineated rings around the cervical portion of the teeth next to the gingival margins. Coffee and tea can cause severe, tenacious brown to black discolorations. Those stains, such as the ones caused by brightly colored foods, are the most difficult to remove from pits, fissures, grooves, or enamel defects.[1,2,3,4] “Bleaching” or “teeth whitening” is the most conservative dental treatment for discolored teeth compared to the other teeth-whitening procedures such as resin-bonded composites, porcelain veneers, and crowns. Methods of tooth whitening have existed for more than 100 years. During the last decade, increased attention to techniques of bleaching has raised safety concerns. Review found 246 citations by cross-referencing hydrogen peroxide with toxicity. There are safety concerns associated with the potential biological effects of free radicals, specifically free radicals of oxygen that are by-products or intermediates of hydrogen peroxide metabolism.[2] Contemporary bleaching systems involve the use of hydrogen peroxide or carbamide peroxide, which can be applied externally, in a procedure known as vital bleaching, or internally, in the pulp chamber, in a procedure that can be used only for non-vital teeth. Both techniques are intended to bleach the chromogens “pigments” in the dentin. Mechanism involved in tooth bleaching is based on the diffusion of hydrogen peroxide through dentinal tubules and the oxidation of pigments. During the bleaching procedure, neither the patient nor the dentist can exactly control the amount of lightening. This technique runs the risk of both over- and under-bleaching. There is a possibility of soft tissue damage due to the caustic nature of the high concentrations of peroxide. There is a greater risk of postoperative sensitivity.[2] Tooth sensitivity was considered as an important side effect of tooth-bleaching agents. Comparative studies have pointed out higher incidence of tooth sensitivity ranging from 67% to 78% after the use of in-office power bleaching method compared with the home vital bleaching method, using 10% carbamide peroxide (15%–65%).[5] There are several reviews that reported on adverse and undesirable effects of bleaching on local hard and soft tissues. Newer bleaching agents with the different activation methods have been incorporated to reduce these untoward effects of bleaching. This study outlines the untoward effects reported by bleaching products introduced within the field of dental bleaching. Hence, the purpose of this narrative review was to report the cervical root resorption, crown fracture, tooth sensitivity, mucosal reaction and enamel surface alterations produced during the treatment, and the management of vital and non-vital teeth-bleaching procedures.
LITERATURE SEARCH STRATEGY
A comprehensive literature search in electronic databases of Scopus, PubMed, Medline, Web of Science, Saudi Digital Library, and Google Scholar databases was performed by using important terms. The key words used were “adverse effects of tooth bleaching,” “adverse reaction of tooth bleaching,” “adverse effects of vital bleaching,” “adverse effects of non-vital bleaching,” “undesirable effects of tooth bleaching,” and “biological effects of dental bleaching.” Adverse effects of cervical root resorption, crown fracture, tooth sensitivity, alteration in enamel surface, and mucosal irritations were reported after carefully analyzing the reported literature.
CERVICAL ROOT RESORPTION
Of the 58 bleached teeth, four teeth with intracoronal bleaching (30% hydrogen peroxide) showed external root resorption. In other study, sodium perborate was used as an intracanal bleaching agent that did not reveal any external root resorption. It has been reported that high concentration of hydrogen peroxide in the presence of heat was found to increase the cervical root resorption. The exact mechanism of cervical root resorption is not clear; however, it was postulated that bleaching agent escapes through dental tubules to reach periodontal tissues and initiates inflammatory process.[6] Care must be taken while using thermo-catalytic bleaching on defective dentinal areas due to the risk of cervical perforation.
CROWN FRACTURE
There is a possibility of crown fracture after intracoronal bleaching, most likely due to the extensive removal of the intracoronal dentin. In addition, use of 30% hydrogen peroxide for the purpose of bleaching in intracoronal area could decrease the microhardness of dentin and enamel and deteriorate the mechanical properties of the dentin.[7] Chauhan et al. reported that the intracoronal bleaching significantly affected the shear bond strength of ceramic brackets after 1 month of bleaching, and perborates affected strength more adversely compared to the hydrogen peroxide and carbamide peroxide bleaching agent. Care must be taken while using thermo-catalytic bleaching on defective dentinal areas because of the risk of cervical perforation.[8]
TOOTH SENSITIVITY
One of the common side effects of external tooth bleaching is the tooth sensitivity. Albanai et al. reported the incidences of dentin sensitivity ranging from 15% to 65% by using 10% carbamide peroxide.[9] Incidence of tooth sensitivity increased in in-office bleach with hydrogen peroxide and heat application. It is common to have tooth sensitivity for 4 days after tooth bleaching, and it ceases at the end of the treatment. However, persistence of tooth sensitivity up to 39 days was also reported within the literature. The exact mechanism concerned with tooth sensitivity is not clearly established; however, in vitro experiments have suggested that peroxide penetrated enamel and dentin and entered the pulp chamber.[10]
EFFECT OF BLEACHING AGENT ON MUCOSAL TISSUES
It has been shown that a high concentration of hydrogen peroxide in the range of 30%–35% is destructive to mucus membrane and may lead to burns and bleaching of the gums. Most of the findings from animal studies have revealed that exposure of the gingiva to 1% hydrogen peroxide for approximately 6–48h damaged the epithelium and caused acute inflammation of subepithelial connective tissue. Various studies reported the effect of tooth-bleaching agent on changes in soft tissue morphology, proliferation of basal keratinocytes, apoptosis of cells in all epithelial strata, and alterations in the expression of cytokines associated with the inflammation.[11] Hence, it is always recommended to use the tray that will prevent gingival exposure by exclusively contacting the teeth.
EFFECT OF BLEACHING AGENTS ON ENAMEL SURFACE
Many studies have reported morphologic changes of enamel after bleaching with various agents. When enamel surface is exposed to the bleaching agent, it showed some morphologic changes compared to untreated control surfaces. Cavalli et al.[10] reported that 35% carbamide peroxide produced the roughest enamel surfaces. Different concentrations of carbamide peroxide produced similar staining means and enamel surface morphological alterations.[12] Türkun et al.[11] showed that 10% carbamide peroxide bleaching materials caused alterations in enamel surface morphology immediately after bleaching, these alterations were dependent on brand and application time. Moreover, these enamel alterations reversed to normal within 3 months.[13] Hence, all the precautions should be taken while planning dental bleaching to avoid further risk of discoloration.
CONCLUSION
In view of this review, it is highly desirable to take all the necessary precautions and considerations while performing tooth-bleaching treatment. It is concerned with various adverse reactions of cervical root resorption, crown fracture, tooth sensitivity, mucosal reaction, and enamel surface alterations. Hence, regular updated knowledge of the bleaching products and techniques is vital to avoid adverse outcomes of teeth-bleaching treatment. Hence, it is necessary for the professionals to inform about the possible adverse reactions of tooth bleaching to the patients.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
REFERENCES
1. Eriksen HM, Nordbø H. Extrinsic discoloration of teeth J Clin Periodontol. 1978;5:229–36
2. Goldstein GR, Kiremidjian-Schumacher L. Bleaching: Is it safe and effective? J Prosthet Dent. 1993;69:325–8
3. Hattab FN, Qudeimat MA, al-Rimawi HS. Dental discoloration: An overview J Esthet Dent. 1999;11:291–310
- Cited Here |
- PubMed
4. Watts A, Addy M. Tooth discolouration and staining: A review of the literature Br Dent J. 2001;190:309–16
5. Nathanson D, Parra C. Bleaching vital teeth: A review and clinical study Compend Newtown Pa. 1987;8:490–2 494, 496-7.
- Cited Here
6. Velloso GR, de Freitas MM, Alves A, Silva A, Barboza E, Moraschini V. Multiple external cervical root resorptions after home whitening treatment: A case report Aust Dent J. 2017;62:528–33
7. Chng HK, Palamara JE, Messer HH. Effect of hydrogen peroxide and sodium perborate on biomechanical properties of human dentin J Endod. 2002;28:62–7
8. Chauhan V, Kumar P, Sharma P, Shetty D. Effect of different intracoronal bleaching methods on shear bond strength of ceramic brackets bonded to bleached enamel: An in-vitro study J Orthod Sci. 2017;6:86–90
- Cited Here
9. Albanai SR, Gillam DG, Taylor PD. An overview on the effects of 10% and 15% Carbamide Peroxide and its relationship to dentine sensitivity Eur J Prosthodont Restor Dent. 2015;23:50–5
- Cited Here |
- PubMed
10. Thitinanthapan W, Satamanont P, Vongsavan N. In vitro penetration of the pulp chamber by three brands of carbamide peroxide J Esthet Dent. 1999;11:259–64
- Cited Here |
- PubMed
11. Alqahtani MQ. Tooth-bleaching procedures and their controversial effects: A literature review Saudi Dent J. 2014;26:33–46
12. Cavalli V, Arrais CA, Giannini M, Ambrosano GM. High-concentrated carbamide peroxide bleaching agents effects on enamel surface J Oral Rehabil. 2004;31:155–9
Keywords:
Bleaching; cervical root resorption; crown fracture; enamel alteration; sensitivity
