Transbond xt

Sixty freshly extracted first premolars were collected, which were mainly extracted for orthodontic purpose and having intact buccal surface. Teeth with heavy restorations, caries and pre-treated with any chemical agent were discarded. All the teeth were stored in a solution of 0.1% (wt/vol) thymol.
All the 60 teeth were randomly divided into two groups:

Group 1 (Control group) – included 30 premolars

Group 2 (Experimental group) – included 30 premolars.

After cleaning the buccal surface of all the 60 premolars with pumice powder and dried with oil – free air source, they were etched with 37% phosphoric acid gel for 30 s.
On premolars in the control group a thin layer of primer (3M Transbond XT) was applied on enamel and bracket base, whereas on premolars in the experimental group a thin layer of Pro Seal was applied on enamel and bracket base. Pro Seal is a highly filled light cured sealant with following contents, ethoxylated bisphenol A diacrylate (10-50%), Urethane acrylate ester (10-40%) and plyethyleneglycoldiacrylate (10-40%) and a proprietary catalyst. The exact percentages of the products are a trade secret. The adhesive (3M Transbond XT) was then applied on the bracket base of both groups (3M Unitek – 0.022” Roth prescription) and bonding done with light cure for 20 s using light-emitting diode source.

Group I – Control Group: 60 teeth were etched with 37% phosphoric acid. Teeth were etched for 40 seconds, rinsed and air-dried. A thin layer of Transbond XT primer (3M Unitek) was applied to the enamel surface and light-cured for 10 s. Brackets were bonded onto the center of the buccal surface of teeth with Transbond XT (3M Unitek), a light-cured composite adhesive. Before curing, the excess resin material is removed with a sharp probe without disturbing the bracket position; the adhesive was light-cured for a total of 40 seconds, following the manufacturer's instruction.
Group – II – Experimental Group: 60 teeth were etched and primed by using self-etching primer that is Transbond Plus (3M Unitek), which contains both the acid and the primer and it is applied on the enamel surface of 60 teeth for 3 s and gently evaporated with air, according to the manufacturer's instructions. For activation, the two components are squeezed together, and the resulting mix is applied directly on the tooth surface. It contains a black (largest) reservoir were squeezed into white (middle) reservoir and then into purple (smallest) reservoir of the blister package using control pressure. The brackets were bonded using Transbond XT adhesive (3M Unitek) and light-cured for 40 s, in the same manner as in Group I.

Specimens were prepared for bracket bonding according to the following procedures: 37% phosphoric acid gel (3M ESPE, Seefeld, Germany) was used to etch the teeth for 30 sec. The teeth were then rinsed with water from a 3-way syringe for 30 sec and dried with an oil-free air source for 20 sec. Subsequently, the liquid primer Transbond XT (3M Unitek, Monrovia, Calif) was applied to the etched surface. MBT premolar stainless-steel brackets (Victory series 3M Unitek) were bonded to teeth with Transbond XT light cure adhesive paste. Excess resin was removed with an explorer before it was polymerized and cured with the following varying procedures:
Group 1: 15 teeth were cured by conventional method of bonding by curing labially for 40 sec
Group 2: 15 teeth were cured for 50 sec by transillumination
Group 3: 15 teeth were cured labially for 20 sec followed by 30 sec of transillumination
Group 4: 15 teeth were first cured by transillumination for 30 sec followed by labial curing for 20 sec.

37% phosphoric acid gel (Sina Co, Iran) was placed on the enamel surface for 15 seconds, washed with water spray for 30 seconds, and dried to a chalky white appearance. The primer solution, Transbond XT (3M Unitek, Monrovia, Calif), was then applied on the etched surface, and then it was light-cured for 5 seconds. Transbond XT composite resin (3M Unitek, South Peck Road, Monrovia, California, USA) was placed on upper premolar metal brackets (Standard-022, Dentaurum, Germany); the bracket was bonded to the tooth surface perpendicular to the long axis of the buccal surface with approximately 250 g force using a manual force gauge (Tension and Compression Gauge, Dentaurum, Germany). In all groups, the brackets were light-cured by LED light-curing unit (Valo, Ultradent, USA) at a light intensity of 1000 mW/cm2 for a total of 20 seconds, with the light beam directed for 10 seconds at each of the mesial and distal faces.