Transbond xt adhesive primer

Shear bond strength was measured with the Instron machine (Instron Corporation, Canton, MA, USA) to evaluate the bracket adhesion of the synthetic bonding resin. The premolars were used for each group (n = 5). This research was approved by the Institutional Review Board of Pusan National University Dental Hospital (PNUDH-2018046). Premolars with no WSL and no other enamel defects were used in this test. The tooth surface was washed with no-fluorine pumice washed with DW for 10 s, and dried. They were etched for 15 s using a 35% phosphoric acid, sucked, washed with water, and then dried. Orthodontic primer (Transbond™ XT adhesive primer, 3M, Nonrovia, CA, USA) was applied to the premolar surface and air was blown over it for 2 s gently. The brackets (Damon orthodontic metal standard edgewise brackets, Ormco, CA, USA) were bonded on tooth surface. The remaining paste was eliminated and then the mesial and distal sites were photopolymerized for 5 s. This entire process was conducted as per the recommendations of the CharmFill Flow manufacturer. The bracket bonded premolar tooth was kept in DW for 24 h and then analyzed using Instron (Crosshead speed: 1 mm/min).

A 0.038 × 0.015 inches gold chain (Reliance Ortho Prod. Inc., Itasca, IL, USA) was bonded between the three premolars of each block. The bonding process consisted of the application of acid etching with ortho-phosphoric acid 37% for 20 s and posterior rinse and dry with water and oil free compressed air. After acid etching preparation, the Transbond XT Adhesive Primer (3M Unitek, Monrovia, CA, USA) was rubbed in a thin layer for three seconds, followed by 20 s of light cured polymerization with a LED lamp (Bluephase, Ivoclar Vivadent AG, Schaan, Liechtenstein). The gold chain was placed with a cotton tweezer and Tansbond XT resin was applied over the surface of both the chain and tooth with posterior light cured polymerization for 20 s. The composition of fixed retention are showed in Table 1.

Orthodontic brackets' bonding was performed by a single calibrated operator, who initially performed the etching procedure by applying 37% phosphoric acid (Dentsply, Petrópolis, RJ, Brazil), only to the gluing site, with the aid of a syringe, for 30 seconds. Next, the enamel was washed with running water for 30 seconds and dried with light jets of oil-free compressed air for 20 seconds. Subsequently, Transbond XT adhesive primer (3 M ESPE, St. Paul, MN, USA) was applied to the conditioned surface with the aid of disposable microbrush applicator, light cured with Valo (Ultradent, South Jordan, UT, USA) for 10 seconds, in standard mode (395–480 nm; 1000 mW/cm²), and a small amount of resin (Transbond; 3 M ESPE) was placed on the base of the Iceram Roth 0.022″ L5A ceramic bracket (Orthometric, Marília, SP, Brazil). The bracket was positioned in the center of the buccal surface of the tooth, with enough pressure to enable the excess material to flow and to be removed with the aid of an exploratory probe. Polymerization was carried out for 40 seconds, 10 seconds on each side of the bracket. Samples were then stored in distilled/deionized water at 37°C for 24 hours.