# Impact of Exposure to Commonly Used Carbamide Peroxide on Dental Pulp Stem Cells
## 1 Introduction  
Aesthetics are philosophical conceptions of beauty that are given high value in modern Western society. In today's society, there is an overwhelming tendency for individuals to project themselves in an optimal manner. Social science research underscores the substantial influence of physical appearance on life experiences, emphasizing its central role as a reflection of individual character. It is human nature to attribute positive personality characteristics to attractive individuals, and this often leads to advantages in various areas of life, such as career opportunities, social status, and romantic relationships [1]. Dentistry has evolved from a primarily medical service to an elective aesthetic service, often at the patient's request [2]. The appearance of teeth has a significant impact on social perceptions; studies show that people with straight, white teeth are seen as more attractive and confident [3]. In addition, there is strong evidence that facial and dental aesthetics significantly influence social judgments, with even children and adolescents evaluating physical attractiveness, including dental appearance, in their social choices [4, 5]. This attitude can often persist into adulthood, where individuals may continue to prioritize physical appearance in their personal and professional relationships [6]. In dentistry, tooth whitening has become an increasingly popular cosmetic treatment, with many patients seeking to improve the appearance of their teeth for aesthetic reasons. This trend is reflected in the growing interest in tooth-whitening treatments in recent years [7]. The most common ingredients used in bleaching are carbamide peroxide and hydrogen peroxide, which are used at various concentrations [8]. Carbamide peroxide is a slower-acting bleaching agent than hydrogen peroxide, and it releases hydrogen peroxide over a longer period of time [9]. This makes it a popular choice for at-home whitening products because it causes less sensitivity than the high-concentration hydrogen peroxide formulations used in dental offices. A 2018 Cochrane review assessed the safety and efficacy of home-based tooth-whitening products. It reported that tooth sensitivity and oral irritation were the most common adverse effects of these products and that these effects were generally mild and transient [10]. Both the organic and inorganic components of the tooth structure undergo significant changes due to the chemical properties of bleaching agents. These changes result in morphological alterations such as increased permeability and surface roughness, which can weaken the tooth's mechanical integrity. Furthermore, bleaching agents can trigger molecular transformations upon reaching the dental pulp, leading to oxidative stress within pulp cells and the subsequent release of pro-inflammatory substances. While bleaching treatments are effective in achieving the desired results, tooth sensitivity remains a prominent side effect. In particular, prolonged exposure to bleaching agents at lower concentrations tends to have more harmful effects on tooth structure [11]. Therefore, it is important to investigate the potential impacts of common dental treatments on dental pulp stem cells, as these cells play an important therapeutic role in maintaining the health and vitality of teeth. By evaluating the impacts of various concentrations of peroxide-based at-home tooth-whitening products on dental cells, including dental pulp stem cells (DPSCs), this study aimed to provide valuable insights into the potential effects of these products on the dental pulp stem cell reservoir. The use of an enamel-dentin or dentin disc model provided a realistic and relevant environment for studying the impacts of peroxide-based tooth-whitening products on DPSCs, as it allowed for the direct and indirect exposure of these cells to the products in a controlled and standardized manner.