title: Internal adaptation, marginal accuracy and microleakage of a pressable versus a machinable ceramic laminate veneers.
abstract: OBJECTIVE
  The aim of this study was to evaluate the internal adaptation and marginal properties of ceramic laminate veneers fabricated using pressable and machinable CAD/CAM techniques.
  
  
  METHODS
  40 ceramic laminate veneers were fabricated by either milling ceramic blocks using a CAD/CAM system (group 1 n=20) or press-on veneering using lost wax technique (group 2 n=20). The veneers were acid etched using hydrofluoric acid, silanated, and cemented on their corresponding prepared teeth. All specimens were stored under water (37 °C) for 60 days, then received thermocycling (15,000 cycles between 5 and 55 °C and dwell time of 90 s) followed by cyclic loading (100,000 cycles between 50 and 100 N) before immersion in basic fuchsine dye for 24 h. Half of the specimens in each group were sectioned in labio-lingual direction and the rest were horizontally sectioned using precision cutting machine (n=10). Dye penetration, internal cement film thickness, and vertical and horizontal marginal gaps at the incisal and cervical regions were measured (α=0.05).
  
  
  RESULTS
  Pressable ceramic veneers demonstrated significantly lower (F=8.916, P<0.005) vertical and horizontal marginal gaps at the cervical and incisal margins and lower cement film thickness (F=50.921, P<0.001) compared to machinable ceramic veneers. The inferior marginal properties of machinable ceramic veneers were associated with significantly higher microleakage values.
  
  
  CONCLUSIONS
  Pressable ceramic laminate veneers produced higher marginal adaptation, homogenous and thinner cement film thickness, and improved resistance to microleakage compared to machinable ceramic veneers.
  
  
  CONCLUSIONS
  The manufacturing process influences internal and marginal fit of ceramic veneers. Therefore, dentist and laboratory technicians should choose a manufacturing process with careful consideration.
authors.affiliation: Dental Biomaterials Department, Faculty of Dentistry, Alexandria University, Egypt.
authors.forename: Moustafa Nabil
authors.initials: MN
authors.lastname: Aboushelib
authors.forename: Waleed AbdelMeguid
authors.initials: WA
authors.lastname: Elmahy
authors.forename: Mohammed Hamed
authors.initials: MH
authors.lastname: Ghazy
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D002484:Cementation / Q000379:methods; D002516:Ceramics / Q000737:chemistry; D004396:Coloring Agents; D017076:Computer-Aided Design; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification*; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D012394:Rosaniline Dyes; D012821:Silanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004396:Coloring Agents; C508050:IPS e.max Press; D019279:Resin Cements; D012394:Rosaniline Dyes; D012821:Silanes; C493120:lithia disilicate; D014867:Water; D003776:Dental Porcelain; C074543:Cerec; C103502:Variolink; C025485:basic fuchsin; D006858:Hydrofluoric Acid