dental materials 28S (2012) e1–e70 e65 P6 Influence of crowns preparation’s geometry and design on stress distribution L.C. Anami ∗ , J.M.C. Lima, E.T.C. Yamamoto, A.L.S. Borges UNESP – Univ Estadual Paulista – FOSJC, Brazil Objectives: To evaluate the influence of preparation’s geometry and design of prosthetic crowns on the stress dis- tribution in compression tests using three dimensional finite element analysis. Materials and methods: Six combinations of three- dimensional drawings of all-ceramic crowns (ceramic based on yttria-stabilized zirconia framework and porcelain veneer) were evaluated – G1: flat preparation and simplified crown (0.5 mm thickness flat framework and porcelain veneer with 1.0 mm thickness); G2: flat preparation and crown with con- tact point (0.5 mm thickness flat framework and veneer with contact point); G3: flat preparation and modified crown (mod- ified framework and veneer with 1.0 mm uniform thickness), G4: anatomical preparation and simplified anatomical crown framework (0.5mm thickness flat framework and porcelain veneer with 1.0 mm thickness); G5: anatomical preparation and crown with contact point (0.5mm thickness framework and veneer with contact point); G6: anatomical preparation and modified crown (anatomical modified framework and veneer with 1.0 mm uniform thickness). Bonded contact-types on all interfaces of the mesh were assigned and the material properties were used according to the literature. A punctual and vertical loading of 200 N was applied at the center of the models. The maximum principal stresses were quantitatively and qualitatively analyzed. Results: The highest values of tensile stress were observed at the interface between the ceramics in the region under the load application for the simplified models, in both cases (G1 and G4), followed by models with contact point (G2 and G5). Reductions in stress values were observed for models with modified infrastructure (G3 and G6). The distribution of stresses in the flat models was similar to their respective anatomical models. Conclusions: It was possible to conclude that the modified design of the zirconia coping reduces the stress concentration at the interface with the veneer ceramic and that the simpli- fied preparation can play a stress distribution similar to the anatomical preparation, when load is applied on the center of the crown. http://dx.doi.org/10.1016/j.dental.2012.07.148 P7 Fatigue resistance of CAD/CAM fabricated full-coverage crowns A.O. Carvalho 1,∗ , G. Bruzi 2 , H.P. Maia 2 , M. Giannini 1 , P. Magne 3 1 Piracicaba Dental School / UNICAMP, Brazil 2 Federal University of Santa Catarina, Brazil 3 University of Southern California, USA Objectives: To compare the fatigue resistance, failure mode and the wear of the antagonist of a new resin nanoceramic material for CAD/CAM with feldspathic and lithium disilicate CAD/CAM materials, of full molar crowns of thickness equal to the minimum recommendation for each material. Materials and methods: Forty-five molars received a stan- dardized full crown preparation and were restored using crown of standardized thickness and occlusal anatomy (third maxillary molar) made by Cerec 3 CAD/CAM system. The restorations (n = 15) were milled from feldspathic and lithium disilicate ceramics (Vitabloc Mark II /VMII and IPS e.max CAD /EMAX, respectively), and a composite resin (Lava Ultimate /LU). The intaglio surfaces of the ceramic restorations were conditioned by hydrofluoric acid etching and silane. Airborne- particle abrasion was used to condition the composite resin restorations. Preparations were airborne-particle abraded. The luting agent used was Unicem II. All restorations were submit- ted to cyclic isometric loading at 10 Hz, starting with a load of 200N (5000× cycles), followed by stepwise loading of 400, 600, 800, 1000, 1200, and 1400 N at a maximum of 30,000 cycles each. The number of cycles at initial failure was recorded. Specimens were loaded for a maximum of 185,000 cycles. The chewing cycle was simulated by an isometric contraction (load control) applied through a composite resin sphere (Filtek Z100) with a diameter of 10.0 mm. After the fatigue test, survived specimens were axially loaded (crosshead speed 0.5 mm/min) until failure or to a maximum load of 4500 N with the same resin sphere. After load tests, the specimens were analyzed for the failure mode: “catastrophic” tooth/root fracture that would require tooth extraction, “reparable” tooth fracture, cohesive fracture or fracture at the interface. Groups were compared using the life table survival analysis (Bonferroni method). Results: LU, E.max and VMII demonstrated survival rate after the fatigue test of 80%, 93.3% and 6.6%, respectively. Survival of restored molars with LU and E.max was no signif- icantly different. All specimens loaded until failure exhibited catastrophic failure with an average load of 3122 N (LU), 3237 N (E.max) and 2500 N (VMII). The antagonistic wear was the low- est with LU crowns. Conclusions: Posterior full crowns made of LU and E.max had significantly higher fatique resistance compared to VMII. LU crowns induce less wear of the antagonist than ceramic crowns. Supported by 3M-ESPE and CNPq (20092/2011-6). http://dx.doi.org/10.1016/j.dental.2012.07.149 P8 Laser treated titanium surface induces differentiation of cal- varial osteoblasts-like cells E. Mariscal-mu ˜ noz ∗ , P.P.C. Souza, H.S. Tavares, J. Bianchi, C.A. De souza costa UNESP, University Estadual Paulista, Araraquara, SP, Brazil Objectives: To evaluate if the irradiation of titanium sur- faces with a high energy laser could improve the biological processes of differentiation and mineralized nodules forma- tion of mouse calvarial osteoblasts in contact with titanium discs. Materials and methods: Forty-eight commercial pure grade IV titanium discs (Titanews Com. de Titânio Imp. Exp. Ltda.,