## 2 Materials and Methods  
A study protocol was designed in accordance with CRIS (Checklist for Reporting Invitro Studies) Guidelines [6]. The protocol described the procedures of the study, including the background, rationale, personnel, and institutions involved; data gathering; data management; specimen storage; materials and equipment; addressing potential bias; and defining the research and its aims. Storage and utilization of used materials were in accordance with recommendations provided by the manufacturers. The study has been approved by the Ethics Committee of the University of Milan, Italy (protocol n. 314), and written consent for the use of extracted teeth was obtained from each patient. De-bonding of BrackFix(r) (Voco GmbH, Cuxhaven, Germany) composite under UV light was compared to the conventional de-bonding method in a blind randomized in vitro test (Figures 1-3). Procedures were performed by postgraduate doctors with similar experience of de-bonding and by experienced operators. To investigate the efficacy of the novel composite, the dental surface after the de-bonding was evaluated by a single experienced operator. Figure 1: Bracket and composite observed under UV light (360–370 nm 20 mW/cm\({}^{2}\)). Operators involved in the study were recruited from the same postgraduate class, from the University of Milan, Italy, with no vision problems. The operators were randomly chosen to perform two types of de-bonding on two different extracted human teeth, the tests were also performed with experienced operators from the same institution. Each of them executed both the new de-bonding procedure of fluorescent composite (DFC) and \"standard\" de-bonding of non-fluorescent composite (DSC) in randomized, blinded order. The sample consisted of 48 human teeth, extracted for various reasons. Inclusion criteria were as follows: good preservation state, integrity, absence of caries, no prior exposure to chemical agents, absence of extraction force generated cracks, and low levels or absence of demineralization. Teeth with minor cracks and small spots of demineralization were included as they are useful for the operator to evaluate enamel integrity in the process of adhesive clean-up. Such cases can be randomly found in patients undergoing or finishing orthodontic therapy. Exclusion criteria included: major cracks, lesions or dental  
Figure 3: Visibility of Composite in two study groups under UV light (360–370 nm 20 mW/cm\({}^{2}\)). Figure 2: Bracket removal under UV light 360–370 nm 20 mW/cm\({}^{2}\). restorations, anatomical abnormalities, or extraction signs on the crown. The sample of 48 human teeth included all teeth types in equal proportions--10 incisors, 10 canines, 14 premolars, and 14 molars. During all procedures, teeth were stored in isotonic solution at 4 \({}^{\circ}\)C with the solution being changed daily for a maximum of 5 days. All the teeth were selected and the inclusion/exclusion criteria were evaluated by an experienced operator prior to the study. The teeth were etched with 37% phosphoric acid gel (Vocoid, Voco GmbH, Cuxhaven, Germany) for 30 s, rinsed with water, and air-dried as recommended by the manufacturer. Stainless-steel brackets (Leone S.p.A, Sesto FiorentinolItaly) were applied to the teeth by a single operator according to manufacturer instructions. Composites (fluorescent and standard) were applied in similar quantities and cured with a light-curing unit with a brightness of at least 1000 mW/cm\({}^{3}\) for 20 s. The novel Composite BrackFix(r) (Voco GmbH, Cuxhaven, Germany) was used for the DFC group. BrackFix(r) primer (Voco GmbH, Cuxhaven, Germany) was applied before application of the composite BrackFix(r). Fluorescent dye added to the composite base of BrackFix(r) allows it to be detectable and seen under the UV light (Figures 1-3). The control group (DSC) was bonded under similar conditions using a non-fluorescent composite Transbond XT (3M, Saint Paul, MN, USA). Teeth were numbered and classified, and 24 teeth pairs were randomly assigned.