# Cytotoxicity of Orthodontic Archives Used in Clinical Practice: In Vitro Study
###### Abstract  
This study investigates the cytotoxicity of various orthodontic archives, which are essential in directing tooth movement through biomechanical forces. With advancements in material science, different archive materials have been developed to balance mechanical performance with aesthetic and biological considerations. The study focuses on evaluating the biocompatibility and mechanical properties of stainless steel, nickel-titanium, and chromium-cobalt archives, particularly their cytotoxic effects on oral cavity cells. In vitro cell culture experiments with fibroblasts, combined with scanning electron microscopy (SEM) analysis, were conducted to assess cell viability and morphology. The results revealed significant differences in cytotoxicity, with copper wires showing high toxicity and causing extensive cell death, while nickel-titanium and chromium-cobalt wires supported better cell viability and healthier cell morphology. These findings highlight the importance of selecting archive materials that ensure mechanical efficiency without compromising cellular health, emphasizing the need for ongoing assessment of material biocompatibility in the oral environment. orthodontic archives; cytotoxicity; biocompatibility; nickel-titanium alloy; chromium-cobalt alloy; stainless steel; fibroblasts; proliferation; in vitro study +
Footnote †: journal: Medical Medical University of Wroclaw, Krakowska 26, 50-425 Wroclaw, Poland; [EMAIL_ADDRESS]  
Footnote †: journal: Medical University of Wroclaw, Krakowska 26, 50-425 Wroclaw, Poland; marcin. The key to successful orthodontic tooth movement lies in the application of uniform, mild forces. Insufficient force does not adequately stress the periodontal ligament (PDL) to initiate movement, while excessive force can slow progress and cause tissue damage. It is widely recognized in the orthodontic field that gentler forces are preferable to achieve superior treatment results compared to stronger ones. Identifying an optimal force range is crucial to facilitate tooth movement through bone remodeling, involving growth, resorption, and renewal. The challenge of overcoming bone resorption at the PDL interface is a significant challenge. Advancements in archive technology aim to produce materials that deliver these optimal forces consistently, reducing the need for frequent adjustments. According to the principles of [PERSON]'s law and Burstone's load deflection rate, an ideal archive is characterized by a low load deflection rate over a wide operating range, aligning with the orthodontic principle of applying ideal forces for treatment [5]. Initially, dentistry used noble metals, combining gold with platinum or copper, until the 1930s, when these were replaced by stainless steel. Today, orthodontic employs several alloys to create metal archives: stainless steel (SS), chromium-cobalt steel (CrCo), nickel-titanium alloys, and titanium-molybdenum (Table 2). Stainless steel (SS), specifically the austenitic stainless steel chromium-nickel blend (Vipla 18/8) blend, is frequently chosen to make orthodontic archives. This blend, consisting of carbon, iron, 18% chromium, 8% nickel and small amounts of manganese, silicon, phosphorus, and sulphur, offers enhanced durability and ductility thanks to nickel, while its rigidity can be adjusted through the annealing process. Chromium contributes to its corrosion resistance by creating a protective oxide coating, though the gradual release of nickel could impact biocompatibility. Compared to nickel-titanium variants, stainless steel wires are less likely to trigger allergies and can be easily manipulated and connected using welding or soldering techniques. They offer an economical solution but are characterized by their rigidity and limited flexibility, which requires more regular adjustment in treatment [1,2]. Elgiloy, a chromium-cobalt steel (CrCo) alloy, is known for its enhanced elasticity and corrosion resistance, attributed to the addition of 40% cobalt and 20% chromium to its base composition.