Automatrix mt

The cavities in all three groups (A, B and C) were etched with 35% phosphoric acid gel (Ultra-Etch, Ivoclar Vivadent AG, Schaan, Liechtenstein) for 20 s, then rinsed for 5 s and partially dried with pieces of gauze until the dentine was moist. A layer of fifth generation adhesive (Adper Single Bond-2, 3 M ESPE, St. Paul, MN, USA) was then applied with a microbrush to all surfaces of the cavity, followed by a gentle stream of air over the liquid for about 5 s until the solvent evaporates completely [24 , 25 (link)]. Then, a LED light-curing unit (Bluephase N, Ivoclar Vivadent AG, Schaan, Liechtenstein) was used at a light intensity of 1200 mW/cm² for 10 s. A circumferential metallic matrix (Automatrix MT, Dentsply, Milford, DE, USA) was adjusted around each cavity for an adequate conformation of the restoration walls.

All cavities were conditioned with 37% phosphoric acid gel for 15 s, then washed with abundant water and dried with sterile gauze balls until dentin was wet, and then a layer of fifth generation adhesive Tetric^® N-Bond was placed with microbrush and air was gently applied for 5 s with a triple syringe to evaporate the solvent [19 (link),20 (link)]. For adhesive light-curing in A1 and A2 groups, a QTH lamp was used with intensity of 700 mW/cm² for 40 s; for B1 and B2 groups, a 3rd generation Bluephase LED lamp was used with intensity of 1200 mW/cm² for 10 s; and for C1 and C2 groups, a 3rd generation Valo LED lamp was used with intensity of 1000 mW/cm² for 10 s. Then, a circumferential metal matrix (Automatrix^® MT, Dentsply, Charlotte, NC, USA) was adjusted around each class II cavity to achieve an adequate conformation of the restoration walls.