Tooth whitening is now the most common elective dental procedure (Dutra et al. 2004), and has proven to be safe and effective when supervised by the dentist (American Dental Association Council on Scientific Affairs 2009). More than 1 million Americans whiten their teeth annually, resulting in nearly $600 million in revenues for dental offices (Dutra et al. 2004). Considering the numerous over-the-counter whitening products available and the heightened consumer interest in whiter teeth, it is the responsibility of the dental profession to educate the public about the efficacy and adverse effects of different tooth whitening modalities, suggest or provide appropriate options based on patient’s needs and preference, and establish reliable and valid monitoring tools for the whitening process.

The variety of methods and products available reflects the high demand for whiter teeth. Traditionally tooth whitening could be classified into three categories: (1) professionally applied in-office whitening with high-concentration materials (Fig. 1.1a); (2) dentist-dispensed patient-applied home-whitening with custom fabricated trays (Fig. 1.1b); and (3) over-the-counter products (Fig. 1.1c) like strips, paint-on gels, or brush-on adhesive liquids (Kwon and Li 2013). With the increased demand and a quest for less expensive options, protocols for do-it-yourself (DIY) whitening (Fig. 1.1d) are now found on the Internet, using natural ingredients such as lemons, apples, and strawberries (Kwon and Li 2013; Natural Teeth Whitening Solutions). The availability of OTC products and various DIY methods has provided the general population better access to whitening, but use without the supervision of a dentist has raised several potential concerns. Tooth discoloration can be the secondary effect of an undiagnosed illness, overuse of whitening materials can damage the enamel surface, and the at-home process might go unmonitored (Hammel 1998; Kwon and Li 2013; Natural Teeth Whitening Solutions). Therefore, the supervision of a dentist or use of custom fabricated trays should be the treatment modality of choice. The patient’s final decision, however, will most likely depend on preference. Although at-home whitening with 10 % carbamide peroxide is safe and effective under a dentist’s supervision (American Dental Association Council on Scientific Affairs 2009), in-office whitening has its merits, especially in elderly patients who may prefer the convenience and in young children who may require full supervision during the entire procedure. Also, patients who cannot tolerate wearing trays and those who desire an immediate effect might also prefer an in-office treatment.

Several studies have compared the efficacy, side effects, and patient acceptance of in-office, at-home, or over-the-counter whitening. Patient opinion was found to depend on the whitening product, study design, application time, and methods of color assessment. One study evaluated the time required to achieve a six-tab difference on a Vita Classical shade guide, and found this occurred the fastest with in-office whitening, followed by at-home whitening, with over-the-counter whitening requiring the most time (Auschill et al. 2005). The various techniques caused similar levels of gingival or tooth sensitivity, and patients tended to prefer at-home whitening, as previously reported (Bizhang et al. 2009; Da Costa et al. 2010; Giachetti et al. 2010; Serraglio et al. 2016). In vitro studies comparing all four whitening techniques showed in-office, at-home, and over-the-counter whitening produced good results, whereas do-it-yourself whitening with strawberry puree was ineffective (Kwon et al. 2015a, b). Despite the equivalencies in endpoint whiteness, a concern remains that DIY whitening could reduce tooth microhardness values (Kwon et al. 2015a). A complete summary, including a comparison of the characteristics of current vital tooth whitening technologies, is listed in Table 1.2. It must be noted that this presents an overall comparison and may vary based on the specific material employed.