Barry Gibson

1 Introduction Cosmetic dentistry, including teeth whitening is gaining increasing attention in dentistry, media and culture. In dentistry, tooth discolouration is defined as a change in the colour and translucency of a tooth and divided into two overlapping categorises: extrinsic—surface stains that are responsive to mechanical removal (e.g., prophylactic brushing) and intrinsic—caused by changes in the internal structure of a tooth [1].

1 Introduction Tooth loss remains a significant public health issue globally, affecting nearly 4 billion people, particularly older adults, worldwide [1, 2]. While advancements in preventive dentistry have led to a decline in complete edentulism, severe tooth loss (defined as having fewer than 9 remaining permanent teeth) remains significantly high in some regions (Brazil, Turkey, Iran, Mexico and New Zealand) [2].

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