title: The effects of hydrochloric acid on all-ceramic restorative materials: an in-vitro study.
abstract: OBJECTIVE
  The aim of this in-vitro study was to assess the long-term effects of hydrochloric acid on the surface roughness of three all-ceramic restorative materials CEREC VITABLOC Mark II CAD, IPS Empress CAD and IPS e.max CAD.
  
  
  METHODS
  Six cylindrical specimens (10mm diameter, 3mm height) of each material type were prepared, using the CEREC CAD/CAM machine. The unpolished samples were immersed in 15ml hydrochloric acid (pH 2) at 37 degrees C. Before immersion (baseline) and at periods of 7.5 hours, 45 hours and 91 hours, the specimens were removed from the acid and two randomised areas (10 microm X 10 microm) were selected and tested on each. The atomic force microscope (Bruker Dimension icon) was used to assess surface roughness and surface area at baseline and after each exposure time. The materials were compared over time with respect to surface roughness and surface area (baseline, 1 month, 6 months, 1 year) in a repeated measures analysis of variance (ANOVA).
  
  
  RESULTS
  Sample groups differed significantly for roughness (p < 0.0001) and surface area (p < 0.0001). For both parameters a significant interaction also existed between material and time (surface roughness: p = 0.0085; surface area: p = 0.0014). CEREC VITABLOC Mark II CAD and IPS Empress CAD had substantially higher levels of roughness and surface area than IPS e.max CAD, which was also affected to a lesser extent over time.
  
  
  CONCLUSIONS
  The results showed that IPS e.max CAD was least affected by long-term exposure to hydrochloric acid.
authors: A
authors: A
authors: Harryparsad
authors: H
authors: H
authors: Dullabh
authors: L
authors: L
authors: Sykes
authors: D
authors: D
authors: Herbst
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry*; D006801:Humans; D006851:Hydrochloric Acid / Q000737:chemistry*; D007101:Immersion; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; C520133:IPS e.max CAD LT; C075815:IPS-Empress ceramic; C493120:lithia disilicate; D003776:Dental Porcelain; C078519:leucite; C074543:Cerec; C023506:Glass ceramics; D006851:Hydrochloric Acid