Mechanical behavior of different machinable ceramic crowns using vertical and horizontal preparations: an in-vitro study

Objective: the aim of this study was to compare mechanical behavior different ceramics when used in thinvertical preparations versus traditional horizontal preparation. Material and Methods: two stainless-steel dieswere milled simulate a minimally invasive vertical preparation (VP) preparation(HP) for an all-ceramic crown maxillary first premolar. The dies were duplicated using epoxyresin. Eighty monolithic crowns divided into 2 groups according design. Eachdesign group subdivided 4 sub-groups material (n=10): IPS e.max CAD (lithium disilicate),Bruxzir shaded zirconia (full contour zirconia), CeraSmart (resin nanoceramic) CEREC Tessera (advancedlithium disilicate). cemented on their relevant epoxy resin self-adhesive cement.All specimens subjected 15,000 thermocycles then loaded fracture universal testing machine.Data analyzed two-way ANOVA Tukey pair wise comparison test. Results: resistancemean values VP (1344 + 118 N) significantly lower than HP design (1646 191 N). Ceramiccrowns made full had higher resistance mean (2842 380 advancedlithium disilicate (1272 125 followed by lithium (983 52 nanoceramic(882 61 Conclusion: both preparations, regardless ceramic materials,showed clinically acceptable values. KEYWORDSDental crown; Prosthodontics; Zirconia; Lithium disilicate; Hybrid ceramics.