Elipar deepcure s

The cavities were roughened with 50 µm aluminium oxide (blasting medium; Dentaurum GmbH & Co. KG, Ispringen, Germany), cleaned with copious water and air dried. The cavities were then pretreated with a silane coupling agent (Porcelain Primer; Bisco, Schaumburg, IL, USA) for 60 s and air dried. A bonding agent (Single Bond Universal; 3M ESPE) was applied to each cavity and light-cured for 10 s (Elipar DeepCure-S; 3M ESPE) after adequate air drying until no visible movement of the bonding agent was observed. Filtek Bulk Fill (3M ESPE) was placed into the cavities using a delivery gun. The tip of the resin compule was initially placed in contact with the cavity floor, and the resin was delivered slowly while the gun was moved away from the cavity floor to minimize entrapment of air in the resin. Resin filling was performed with two different layering techniques (incremental filling with two 2-mm-thick layers and bulk-filling with a single 4-mm-thick layer). Each layer was packed for 10 s with two strokes per second using a 2-mm-diameter tip on the vibratory device specifically designed for resin application (COMO; B&L Biotech) with or without vibration (no vibration vs. vibration) (n = 10) (Fig. 1D). Light-curing was performed for 20 s after placement of each layer.

The compositions of the main materials used in the present study are given in Table 1. Seventy-eight specimens (diameter: 10 mm) were fabricated by placing three 1.5 mm thick composite increments (Filtek Supreme XTE, 3M, St. Paul, MN, USA; color A4D) on scanning electron microscope (SEM) carriers using cylindrical Teflon molds. To achieve a flat surface, the composite surface was leveled using a PTFE-roller (CompoRoller TM 5300, KerrHawe, Bioggio, Switzerland). Photo-activation was performed for 20 s at 1500 mW/cm² (Elipar Deepcure-S, 3M). Subsequently, the 78 specimens were randomly assigned to 13 groups of six specimens each (Figure 1). Specimens of the positive control group (group 1) were immediately processed further, while all other groups were polished under constant water cooling with 4000-grit silicon carbide (SiC) paper (Buehler-Met II, Buehler, Esslingen, Germany). Prior to the conditioning steps, groups 2–13 were aged in a thermocycling machine (Haake W15, Thermo, Willytec, Gräfelfing, Germany) for 5000 cycles between 5 °C and 55 °C (dwell time: 20 s in each bath; transfer time: 10 s; duration of each cycle: 50 s), as described by Wiegand et al. [26 (link)].

To effectively achieve the maximum concentration of eluates, methanol (99.9%, Sigma-Aldrich) was used as an eluent. Three disc-shaped specimens (TN, CX, and DN) with 13 mm in diameter and 1 mm in thickness were fabricated in a Teflon mould and light-polymerised (Elipar DeepCure-S, 3M ESPE). The top surface remained open to simulate the clinical situation of an oxygen-inhibited layer, while the bottom was covered with a glass slide. The samples were immersed in methanol and eluted for 24 h at 37 °C in brown glass vials (3 cm²/mL).