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The roots of all teeth were embedded in a 25 mm diameter cylinder using a self-curing acrylic resin. The insertion of the teeth was carried out using a dental surveyor so that the occlusal surface of the tooth remained parallel to the cylinder base and the cementoenamel junction (CEJ) was positioned 2 mm above the resin level to simulate the bone tissue.
Two impressions of the occlusal surface of each tooth were made using polyvinylsiloxane Express XT (3M-ESPE, St. Paul, MN, USA). The first mold was sectioned in a buccopalatal direction and provided guidelines for a depth check of the cavity's occlusal box. The second mold was then used to reproduce the original shape and volume of the occlusal surface of each tooth.
Teeth were randomly divided into 4 groups (Table 1). In groups I, BF3 and BF1, cavities were prepared to simulate class II MOD cavities using the diamond bur no. 3131 (KG Sorensen, Cotia, SP, Brazil) at high speed under constant cooling with water and air. A new diamond bur was used for every preparation. Tooth preparation was standardized with a millimeter probe and silicone mold (Fig. 1). After completion of preparation, the cavities presented an occlusal box with 2.0 mm depth and 2.5 mm buccopalatal width, an a proximal box with 4 mm depth and 1.5 mm in the pulp direction (Fig. 1).

Twelve samples (7 mm x 2 mm x 1 mm) of each group were made in polyvinylsiloxane matrices (Express XT, 3M ESPE, St. Paul, USA), according to ISO 178: 2001 specifications, except for length. Lightcuring of the samples was conducted for 40 seconds, under a mylar strip, and the specimens were stored for 24 hours at 37ºC.
The three-point bending test was performed in a universal testing machine (Instron, Model 4111, Instron, Canton, USA), with a 5-mm distance between the holders, at 0.5 mm/min speed and 50 N load, until the fracture of the samples. Prior to the test, the dimensions of each specimen were obtained with a digital caliper (Mitutoyo, Tokyo, Japan), and then transferred to Bluehill 2 software (Instron, Canton, MA, USA) to calculate the elastic modulus in GPa and the flexural strength in MPa, according to dimensions and strain.

Sorption and solubility tests were based on ISO 4049: 2009 specifications, except for the sample size, and the water volume (mL) used. Disc samples of the infiltrants were prepared (5 mm x 1 mm, n = 5) in polyvinylsiloxane molds (Express XT, 3M ESPE, St. Paul, USA) that had been previously made in a Teflon matrix.
Right after light-curing, the samples were stored in a desiccator containing silica gel at 37ºC. The specimens were weighed repeatedly at 24-hour intervals for 4 days until a constant initial mass (m1) was obtained, with a variation of less than 0.1 mg. The thickness and the diameter of the samples were measured using a digital caliper, and the measurements were then used to calculate the volume (V) of each specimen (in mm 3 ).
Afterwards, the specimens were stored individually at 37°C in Eppendorf vials containing 2 mL of distilled water. After seven days of water storage, the samples were removed from the incubator and left at room temperature for 30 minutes. The specimens were then washed in running water, dried with absorbent paper, and weighed on an analytical scale (m2). The samples were further dried in a desiccator containing silica gel, and weighed daily until a constant mass (m3) was obtained, a process that took 6 days in this study. The sorption (So) and solubility (SL) values were calculated using the following formulas: So = (m2-m3) / V; SL = (m1-m3) / V.