Following surface selleck chem Regorafenib debridement with a hand-scaling instrument and cleaning with a rubber cup and slurry of pumice, the teeth were examined at 20 X magnification under a dissecting microscope to discard those with any visible structural defects, cracks, or carious lesions. Selected teeth (n = 50) were stored at 4��C in 0.9% w/v NaCl for a maximum of 1 month. One operator prepared standardized class I cavities with an ISO #014 cylindrical diamond bur in a high-speed handpiece under copious water spray. No bevels were added at the preparation margins. The teeth were randomly assigned into 5 groups (n = 10/each) with regard to filling material and/or presence of an SC: Group 1: Conventional GIC (Ionofil U, VOCO, Cuxhaven, Germany) without an SC.
Group 2: Conventional GIC (Ionofil U, VOCO, Cuxhaven, Germany) with an SC (Heliobond, Ivoclar Vivadent, Schaan, Liechtenstein). Group 3: Glass carbomer cement (Glass Carbomer Products, Leiden, Netherlands) without an SC. Group 4: Glass carbomer cement (Glass Carbomer Products, Leiden, Netherlands) with an SC (Glass Carbomer Surface Gloss, Glass Carbomer Products, Leiden, Netherlands). Group 5: Compomer (Dyract Extra, Dentsply, Konstanz, Germany) without an SC. All the materials were handled and applied by 1 calibrated operator in strict accordance with the manufacturer��s instructions. For the glass carbomer cement, photopolymerization of the surface gloss was accomplished using Elipar S10 LED Curing Light (3M ESPE, Seefeld, Germany), which is one of the proprietary high-energy light curing units recommended by the manufacturer.
Heliobond and Dyract Extra were light cured using a quartz-tungsten-halogen curing unit (Optilux 501, Kerr; Danbury, CT, USA). After completion of restorative procedures, samples were stored in distilled water at 37��C for 24 h, and then subjected to thermocycling (2000��, in 5 �� 2��C to 55 �� 2��C with a dwell time of 15 s and a transfer time of 10 s). Microleakage test and image analysis The root apices were sealed with a sticky wax to prevent dye penetration. The samples were coated with 2 consecutive layers of nail varnish up to 1 mm from the restoration margins. Then, samples were immersed in 0.5% basic fuchsine solution (Wako Pure Chemical Industry, Osaka, Japan) for 24 h. Thereafter, samples were rinsed thoroughly under tap water, air dried, and embedded in a phenolic ring with epoxy resin (Struers, Copenhagen, Denmark).
Three parallel longitudinal sections were made through the restorations18 using a low-speed, water-cooled diamond saw (Isomet, Buehler, Lake Bluff, IL, U.S.A.) in the buccolingual direction. For each specimen, the dye penetration along the buccal and lingual margins on each of the 3 sectioned surfaces was digitally photographed at 20�� (1280 �� 1024 resolution) Carfilzomib under a stereomicro-scope (Olympus, Tokyo, Japan) and transferred to a Macintosh PowerPC Workstation.