###### Abstract  
This study aims to analyze the effect of desensitizing agents on the shear bond strength (SBS) of ceramic brackets after in-off bleaching procedures. Twenty-seven extracted premolars were equally divided into three groups (n = 9). Group 1 served as the control; bleaching was performed with 37% hydrogen peroxide. In group 2, bleaching and the application of a fluoride-containing desensitizing agent (CPP-ACFP) were performed. In group 3, bleaching and the application of a non-fluoride-containing desensitizing agent (CPP-ACP) were performed. Ceramic brackets were bonded with composite resin. SBS was tested using a universal testing machine. The site of bonding failure was measured using the adhesive remnant index (ARI) score. There was a statistically significant difference in mean SBS values (\(p\) < 0.05). Group 1 showed the lowest SBS value (6.32 \(\pm\) 4.83 MPa), which differed significantly with groups 2 and 3 (\(p\) < 0.05). There was no significant difference between group 2 (15.36 \(\pm\) 4.67 MPa) and group 3 (12.19 \(\pm\) 6.81 MPa) (\(p\) > 0.05). The ARI score did not show a significant difference. The conclusion is that the application of fluoride-containing and non-fluoride desensitizing agents increases the shear bond strength of ceramic brackets on bleached teeth with composite resin cementation. The application of both desensitizing agents had no impact on the results of the ARI score, with the highest ARI score in each group being 4, indicating that less than 10% of the adhesive substance remains on the enamel. shear bond strength; desensitizing agent; in-office bleaching; ceramic; bracket +
Footnote †: journal: Medical  
how well adhesive resin bonds to previously bleached enamel. Prior studies report that bleaching can decrease the shear bond strength of orthodontic brackets [8; 9; 10]. Bleaching agents may impact the structure by decomposing organic and inorganic components, and they may also impact the morphology of enamel by causing porosity, cavities, depression, deeper enamel, loss of as prismatic layers, and a rough surface [11]. In-office bleaching temporarily reduced enamel microhardness and increased surface roughness [12]. Patients frequently mention dentin hypersensitivity as a side effect of bleaching therapy, in addition to tooth morphological changes. Some researchers theorize that post-bleaching hypersensitivity is caused by the direct activation of nerve receptors in the tooth's structure by hydrogen peroxide, resulting in increased pain [7; 13]. Utilizing a desensitizing agent is one of the methods that have been employed to reduce post-bleaching hypersensitivity. Desensitizing agents have two distinct modes of action. The degeneration of dental tubules, which prevents the passage of dental fluids and promotes remineralization, is required for one process. The second one reduces the sensory excitability of nociceptor by inhibiting pulp nerve activity [14]. Desensitizing agents include both fluoride and non-fluoride-containing substance, such as casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACFP) and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) [15]. Along with the need for orthodontic and cosmetic treatment, the popularity of ceramic brackets has grown and is becoming a popular choice, particularly for adult patients who desire orthodontic treatment without compromising aesthetics. Ceramic brackets were introduced to the dental profession in an effort to meet patients demands for aesthetics and were first utilized in clinical settings in 1987. Ceramic brackets are made of aluminum oxide [16]. They offer numerous benefits over stainless steel brackets, including biocompatibility, good aesthetics, resistance to chemical and temperature changes, and good adhesive strength [17]. Furthermore, dental ceramic also has limitations, such as fractural strength and wear resistance [18]. There is currently no research on the effect of post-bleaching desensitizing agents on the shear strength of enamel and bracket attachment.