In Vitro Aging Environment Study Of Inlay Restorations A. Cerutti*, P. Menghini, P. Donati, A. Putignano, G. Merlati (School Of Dentistry, Pavia University-Brescia University-Ancona University) The aim of our "in vitro" study was to assess the microleakage and the marginal sealing ability IPS-Empress® inlay restorations (Ivoclar-Vivadent) performed with different luting-cement systems. Introducing an innovative automatic aging thermocycling test "Thermocycler FCA14®" which perform an automatically specimens exposure in a 5% methylene blue water solution, we applied the microleakage testing protocol of the ISO/TR 11405:1994 standard concerning the adhesion to tooth structure to asses marginal adaptability and fit. Ten sound human teeth (mandibular and maxillary molars) were prepared for class Il MOD and MO restorations and divided randomly in three experimental groups (n=3) and one control sample. The inlays were performed with three different luting agents (Variolink II® (Vivadent), Resin Cement® (3M), Nexus® (Kerr) and initial replicas were performed. The automatically thermocycling test has been defined as a 5.000 cycles of temperature fluctuation, ranging between 5°C and 50°C, with a 30"dwell time and a 5"translation period, in a 5% methylene blue aqueous solution. After test stressing, we realised two epoxy resin replicas for each restoration (Epoxident®, USA) by two elastomeric impression materials (President®) and Impregum/Permadyne®) in order to apply a SEM surface analysis suitable to asses the marginal fit (SEM 123, Philips). Tooth specimens were sectioned in order to obtain at least 12 and 8 surfaces to evaluate dye penetration. Axial tooth surface was directly and optically evaluated by a stereomicroscope (Carl Zeiss), magnification 20X, dye penetration along enamel and dentinal surface (Dentinal) and between inlay-luting agent couples (Interface) were measured with a high sensitive score penetration table and graded from 0 to 5 (Eakle et Al., Dental Materials. 1989).   Statistical analysis of results has been performed using T-test and non parametric tests (Kruskall-Wallis and Mann-Whitney) and considering significant with p<0.05. We noted a remarkable dye spreading inside the luting agent thikness (Interface). A statistical difference (p<0,05) was recorded between the adhesion efficiency (Dentinal) and the dye infiltration phenomena of the luting agent (Interface). Statistical evaluation (Kruskall-Wallis test)did not report any significant difference (p>0,5) between microleakage behaviour in the different kinds of resin luting, agents in Dentinal and Interface. Analisy of data (Mann-Whitney test) shows statistical difference (p<0,05) in dye penetration between cervical box and occlusal margin, this behaviour is present in Dentinal and Interface leakage scores. The dye spreading in the luting agent system seems to be a failure at the inlay-luting system interface. This phenomena, in our study, was proportional to layer size. Automatic aging thermocyclig test "Thermocycler FCA 14" could be an appropriate and important test in determining material properties of dental restorations.