Tooth chromophores

Tooth chromophores are the diverse organic and inorganic molecules embedded within the dental hard tissues (enamel and dentin) or adsorbed onto the tooth surface that are responsible for visible tooth color and discoloration. These molecules, which include porphyrins, carotenoids, and polyphenolic compounds from diet or systemic sources, typically possess long chains of conjugated double bonds that absorb specific wavelengths of light [1][3]. In the context of aesthetic dentistry, these chromophores are the primary therapeutic targets for whitening agents like hydrogen peroxide and carbamide peroxide. These agents penetrate the porous structure of the enamel to reach the dentin, where they undergo an oxidation-reduction reaction that disrupts the chromophore's chemical structure, rendering it colorless [2]. Understanding the specific nature of these chromophores—whether they are extrinsic (surface-level) or intrinsic (incorporated into the matrix)—is critical for selecting the appropriate concentration and duration of bleaching treatment. Pathological staining, such as that caused by tetracycline or excessive fluoride, involves the formation of stable complexes with the hydroxyapatite crystal lattice, making these chromophores particularly resistant to standard oxidation [4]. Consequently, tooth chromophores represent a unique non-protein target in clinical pharmacology focused on dental aesthetics and restorative health. [1] Joiner, A. (2006). The bleaching of teeth: A review of the literature. Journal of Dentistry. [2] Epple, M., et al. (2019). A Critical Review of Modern Concepts for Teeth Whitening. Dentistry Journal. [3] Watts, A., & Addy, M. (2001). Tooth discolouration and staining: a review of the literature. British Dental Journal. [4] Sanchez, A. R., et al. (2004). Tetracycline and other tetracycline-derivative staining of the teeth and oral cavity. International Journal of Dermatology.

Other names

Dental chromophoresTooth pigmentsIntrinsic stainsExtrinsic stainsTooth discoloration agents

Bleaching agents act as oxidizing agents that produce free radicals (such as hydroxyl radicals) which attack the conjugated double bonds of the chromophore molecules. This oxidative cleavage breaks the large, pigmented molecules into smaller, less-pigmented or colorless fragments, thereby increasing the lightness (L*) and reducing the yellowness (b*) of the tooth structure [1][2].