Romanian JouRnal of Stomatology – Volume 68, no. 3, 2022 124 The relationship between light curing time, shear bond strength (SBS) and remanence index of adhesive (ARI) Mahmoud El Saafin 1 , Cristina Stanca Molnar 2 , Irina Zetu 3 , Daniela Manuc 4 , Simina Neagoe 5 , Mariana Pacurar 1 1 Orthodontic Department, Faculty of Dentistry, "G.E. Palade" University of Medicine, Pharmacy, Science and Technology, Targu Mures, Romania 2 Dental Materials Department, Faculty of Dentistry, "G.E. Palade" University of Medicine, Pharmacy, Science and Technology, Targu Mures, Romania 3 Orthodontic Department, Faculty of Dentistry, ”Gr.T. Popa” University of Medicine and Pharmacy, Iasi, Romania 4 Preventive Dentistry Department, Faculty of Dentistry, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania 5 Periodontology Department, Faculty of Dentistry, "Titu Maiorescu" University, Bucharest, Romania CLINICAL STUDIES ABSTRACT The objective of this study is to investigate the effect of different light curing times on the shear strength and remanence index of the adhesive. The light curing intensity was presented by Woodpecker LED light curing unit (2500 mw/cm 2 ). The study was performed on groups of extracted premolars: The first and second groups had a light-curing time of 3 seconds, and the third and fourth groups had a light-curing time of 6 seconds. However, the first and third groups were tested after 24 hours, and the second and fourth groups after 14 days. The study showed that increasing the light curing intensity, exposure time and the time after the brackets bonding will increase SBS and will decrease ARI on the other hand, using light curing unit (2500 mw/cm 2 ) with 6 seconds light exposer will produce sufficient SBS, and 3 seconds light cure exposer (2500 mw/cm 2 ) will produce insufficient SBS. Keywords: SBS, ARI, bracket, bonding, light curing, enamel, adhesive Ref: Ro J Stomatol. 2022;68(3) DOI: 10.37897/RJS.2022.3.6 Corresponding author: Cristina Stanca Molnar E-mail: molnar.stanca@gmail.com Article History: Received: 24 September2022 Accepted: 30 September 2022 INTRoDuCTIoN More than 40 years ago, orthodontic brackets were initially attached directly to teeth. The tooth surface and its preparation, the design of the attach- ment base, and the bonding substance itself must all be carefully taken into account for a good bonding in orthodontics. The type of enamel conditioner used, the acid concentration utilized, the length of the etching pro- cess, the adhesive composition used, the shape of the bracket base, and the material used for the brackets are all factors that affect bond strength [1]. In orthodontics, light-activated bonding agents have become the preferred polymerization method. Numerous factors can influence the light intensity during exposure and thus change the properties of the cured composite. Maintaining strong light intensities both on the resin surface and throughout the substance helps polymerize the resin. The exact distance between the tip of the activating light source and the surface of the resin being exposed is one of the elements that affect light intensity, and that the practitioner can control. To avoid in-tensity loss, this distance should be kept as small as possible. In addition, the in-tensity of the light emitted from the light tip de- creases in inverse proportion to the square of the distance between the tooth and the tip. However,