title: Marginal gap, internal fit, and fracture load of leucite-reinforced ceramic inlays fabricated by CEREC inLab and hot-pressed techniques.
abstract: OBJECTIVE
  This in vitro study was designed to evaluate and compare the marginal gap, internal fit, and fracture load of resin-bonded, leucite-reinforced glass ceramic mesio-occlusal-distal (MOD) inlays fabricated by computer-aided design/manufacturing (CAD/CAM) or hot pressing.
  
  
  METHODS
  Fifty caries-free extracted human molars were prepared for standardized MOD inlays. Impressions of each specimen were made and poured using type IV dental stone. Dies were randomly divided into two equal groups. Twenty-five ceramic inlays were fabricated by the hot-pressed technique using IPS Empress leucite-reinforced glass ceramics, and the other 25 ceramic inlays were produced by CAD/CAM technology using ProCAD leucite-reinforced ceramic blocks and CEREC inLab facilities. Inlays were bonded to the teeth using a dual-cured resin cement. The specimens were stored in distilled water at 37°C for 24 hours and then thermocycled for 5000 cycles. The marginal gap measurements were taken with a stereomicroscope. Specimens in each group of inlay systems were randomly divided into two subgroups of 10 and 15 specimens each. Ten specimens in each subgroup were sectioned mesiodistally for evaluation of the internal fit. The fracture load of specimens in the second subgroup (n = 15) of the two inlay systems was determined under compressive load in a universal testing machine. Data were analyzed using Student's t-test at a significance level of p < 0.05.
  
  
  RESULTS
  The mean marginal and internal gap size in both IPS Empress and ProCAD inlays were less than 100 μm; however, the marginal gap for the IPS Empress restorations was significantly higher than that of ProCAD restorations (p < 0.05). There was no significant difference in the mean internal fit or the fracture load between the two glass ceramic inlays (p > 0.05).
  
  
  CONCLUSIONS
  The leucite-reinforced glass ceramic inlay restorations fabricated by CEREC inLab (CAD/CAM) and the hot-pressed technique provided clinically acceptable marginal and internal fit with comparable fracture loads after luting.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Shahed University, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Keshvad
authors.forename: Tabassom
authors.initials: T
authors.lastname: Hooshmand
authors.forename: Farokh
authors.initials: F
authors.lastname: Asefzadeh
authors.forename: Foroogh
authors.initials: F
authors.lastname: Khalilinejad
authors.forename: Mohammad
authors.initials: M
authors.lastname: Alihemmati
authors.forename: Richard
authors.initials: R
authors.lastname: Van Noort
mesh_terms: D000538:Aluminum Silicates; D002484:Cementation; D017076:Computer-Aided Design; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design / Q000379:methods; D019232:Dental Restoration Failure; D006801:Humans; D007284:Inlays; D008422:Materials Testing; D008963:Molar; D011312:Pressure
chemical_list: D000538:Aluminum Silicates; D003776:Dental Porcelain; C078519:leucite