Microhybrid Composite Vs Dual Curing Cement In Luting Composite Inlays C. Stacchi*, M. Cadenaro, R. Di Lenarda (Priv. Pract., Inst. Odontol, Univ. Trieste) The aim of this study is a comparative evaluation of a microhybrid and a dual curing composite resin behaviour in luting composite inlays on human teeth, using halogen and plasma curing lamps.   We prepared 24 occlusal cavities, using inlay burs on extracted human teeth (12 molars and 12 premolars). The cavity depth was 3 mm. The cavity walls were diverging (15°) with butt margins. After the application of two layers of Lab-Separator Coltene on the cavity walls we prepared 24 inlays using Filtek Z250 3M composite resin, A3.5 shade, with incremental technique. Each layer of the material (max thickness 2 mm) was polymerized using an Apollo 95E D.M.D.S. Ltd. lamp, with three occlusal light expositions of three seconds each.   After being removed from the cavities, the inlays were additionally photo and thermo-polymerized for 9 minutes in a Coltene D.I. 500 oven; then they were lightly reduced on the pulpal and axial surfaces with a diamond bur respecting the margins. The inlays were sand-blasted with Al2O3 for 2 sec. (Danville Microetcher), silanyzed with Silane Pulpdent and covered with a layer of Scotchbond 1 3M.   The cavities were totally etched for 45 sec' with the UltraEtch 35% phosphoric acid, washed for 30 sec, gently dried and covered with a layer of Scotchbond 1 3M. Teeth were divided into two groups of 12 specimens (6 molar and 6 premolars). In group 1 Z250 composite resin was placed on the pulpal and axial walls; in group 2 the dual cure cement Relyx ARC 3M was applied.   In both groups the inlays were placed and adapted into the cavities applying an ultrasonic tip for 30 sec and then polymerized (subgroups A and B) with the following protocol:   Groups 1A and 2A with Curing Light 2500 3M lamp (830 mW) occlusally, buccally and lingually for 3 min each; Groups 1B and 2B with Apollo 95E D.M.D.S. Ltd. lamp (1930mW) occlusally, buccally and lingually for 1 min each.   Teeth with luted inlays were stored in physiologic solution till they were embedded in resin and sectioned in three buccal - lingual sections with a microtome cooled under tap water.   The sections were analysed with a 64x magnification stereomicroscope to evaluate the quality of the tooth - inlay interface and the Vickers microhardness of the luting agents on the bottom of the cavity, on the pulpoaxial corners and on the axial walls every half millimeter of depth was measured.   The one-way ANOVA and Scheffè tests were performed and no statistical differences were found between photo and dual curing composite, when the plasma light curing lamp was used.   Inforced composite IFPDs were considered clinically successful over the observation period.