title: Effect of Aging Regimens on Resin Nanoceramic Chairside CAD/CAM Material.
abstract: OBJECTIVE
  To evaluate the effect of cyclic mechanical loading, thermal cycling, and storage in water on a resin nanoceramic chairside computer-aided designed/computer-aided manufactured (CAD/CAM) material compared to a control leucite-reinforced glass-ceramic material.
  
  
  METHODS
  One hundred twenty specimens (18 × 4 × 3 mm) were milled from two chairside CAD/CAM materials' blocks (Lava Ultimate: LU; Vitablock Mark II: VM). Each group included four subgroups (A: n = 20 control; B: n = 20 cyclic loading [105 cycles, 80 N]; C: n = 20 thermal cycling [5 to 55°C]; D: n = 60 water storage [20: 3 months; 20: 6 months; 20: 9 months at 37°C]). Each subgroup included 10 specimens tested for flexure strength using three-point bending in a universal testing machine. The other 10 specimens were tested for surface roughness using an automated profiler followed by testing for surface hardness using a microhardness tester.
  
  
  RESULTS
  LU displayed higher flexure strength than VM before and after all the aging conditions. The surface roughness for VM was lower than LU for the control, but both materials showed comparable values and significant increases after 9 months storage in water. After cyclic loading, only VM displayed a significant increase in the surface roughness value (p < 0.05). The surface hardness of VM was higher than LU for the control. VM did not show significant changes in hardness after any aging condition. LU showed significant reduction in surface hardness value only after storage in water (p < 0.05).
  
  
  CONCLUSIONS
  The resin nanoceramic Lava Ultimate can be used as a durable substitute for glass-ceramic chairside CAD/CAM material.
authors.affiliation: Associate Professor and Chairman of Substitutive Dental Sciences Department, College of Dentistry, University of Dammam, Kingdom of Saudi Arabia.
authors.forename: Fahad A
authors.initials: FA
authors.lastname: Al-Harbi
authors.affiliation: Associate Professor, Restorative Dental Sciences Department, College of Dentistry, University of Dammam, Kingdom of Saudi Arabia, Assistant Professor, Dental Biomaterials Department, Faculty of Dentistry, Mansoura University, Egypt.
authors.forename: Neveen M
authors.initials: NM
authors.lastname: Ayad
authors.affiliation: Assistant Professor, Substitutive Dental Sciences Department, University of Dammam, Dammam City, Kingdom of Saudi Arabia.
authors.forename: Aws S
authors.initials: AS
authors.lastname: ArRejaie
authors.affiliation: Professor, Restorative Dental Sciences Department, College of Dentistry, University of Dammam, Kingdom of Saudi Arabia, Professor, Dental Biomaterials Department, Faculty of Dentistry, Cairo University, Egypt.
authors.forename: Hala A
authors.initials: HA
authors.lastname: Bahgat
authors.affiliation: Professor and Director, Hugh Love Center for Research and Education in Technnology, Loma Linda School of Dentistry, CA.
authors.forename: Nadim Z
authors.initials: NZ
authors.lastname: Baba
mesh_terms: D002516:Ceramics; D017076:Computer-Aided Design; D017266:Dental Prosthesis; D017267:Dental Prosthesis Design; D006244:Hardness; D006801:Humans; D049329:Nanostructures; D012117:Resins, Synthetic; D013499:Surface Properties
chemical_list: D012117:Resins, Synthetic
keywords: CAD/CAM; Chairside; mechanical loading; resin nanoceramic; thermal cycling; water storage