## 1 Introduction  
Orthodontic brackets, pivotal in levelling and aligning teeth, have evolved significantly since their inception. Initially, the gold standard involved bonding brackets onto stainless-steel bands, transitioning in the late 1970s to direct bonding onto enamel, which became the predominant method. Subsequent modifications aimed to enhance bond strength through base design alterations and adhesive use, facilitating the effective application of orthodontic forces. The rising demand for aesthetic solutions fueled advancements in bracket design and bonding techniques [1]. The process of bonding orthodontic brackets has undergone significant advancements, largely driven by innovations such as enamel acid-etching, pioneered by Buonocore in 1955, which marked a pivotal moment in adhesive dentistry [1, 2]. Since the advent of orthodontic bracket bonding by Newman, various bonding agents have been developed to enhance adhesion strength and precision [3]. One notable advancement is the introduction of light-cured materials, initially described by [PERSON] and [PERSON], which enable precise bracket placement and ensure a robust bond at the enamel-composite interface [4]. Debonding is the procedure of removing the brackets, along with adhesive resin from the tooth surface. Various methods exist, each with its potential impact on enamel integrity. Factors such as bracket type, bonding agent type, and debonding instruments influence the extent of enamel damage. Metal or stainless-steel brackets have shown less risk of enamel fracture than ceramic brackets [5]. Evaluating the adhesion quality between the composite, tooth, and bracket base is crucial. This assessment is commonly conducted using the Adhesive Remnant Index (ARI) method, which provides insights into the distribution and strength of adhesive remnants following bracket removal [6; 7]. The integrity of the bonds between metal-composite and composite-enamel are crucial for treatment efficacy and patient oral health. These bonds must withstand orthodontic forces and intraoral stresses throughout treatment [8; 9]. However, conducting in vitro studies to assess these adhesive systems presents challenges. Thermocycling involves subjecting materials to alternating temperature variations to simulate oral conditions and assess their durability [10; 11; 12]. It is a laboratory method that exposes dental materials and teeth to ranges of temperatures comparable to those occurring in the oral cavity, which could result in adverse consequences such as damage or weakening of the materials due to various coefficients of thermal expansion between the tooth structure and the filling material. During these cycles, thermal stresses may impact the bond strength between the repairing or filling material and the tooth structure [13; 14; 15; 16]. Thermocycling is considered one of the most severe thermal environments [17]. Adhesive failure can occur at any interface between the bracket, adhesive, and enamel or at a number of different sites. Factors influencing detachment site include the tooth preparation technique (curing technique), bonding material type, and debonding method [1; 8]. Previous research [8; 18; 19] evaluated the effect of the removal of different types of brackets on tooth enamel. Enamel microcracks (EMCs), often overlooked but crucial, can result from debonding procedures, potentially leading to long-term complications, including tooth fracture, demineralization, and esthetic concerns [20]. Given the critical role of metal bracket bonding and subsequent debonding in orthodontic procedures, this study aimed to investigate the impact of thermocycling, orthodontic bonding agents, and curing techniques on the enamel layer following metal bracket debonding. While previous research has explored the influence of different bonding agents and curing methods on EMCs, limited attention has been given to thermocycling tests as an evaluation parameter.