title: Effects of Simulated Gastric Juice on CAD/CAM Resin Composites-Morphological and Mechanical Evaluations.
abstract: OBJECTIVE
  To evaluate the effects of simulated gastric juice on CAD/CAM resin composites by means of morphological and mechanical (i.e., hardness) evaluations.
  
  
  METHODS
  Fourteen specimens of each resin composite (Lava Ultimate and Paradigm MZ100) were prepared according to the manufacturer's instructions. They were submitted to erosive challenges in a simulated gastric juice (pH = 1.2) solution for 6 and 24 hours. Vickers microhardness and surface roughness (Ra, Rq) evaluations were taken before (baseline) and after acid exposure. Morphological analysis was obtained using scanning electron microscopy (SEM). Statistical analysis was performed using two-way repeated measures ANOVA and Student-Newman-Keuls's test (α = 0.05).
  
  
  RESULTS
  Paradigm MZ100 demonstrated higher microhardness than Lava Ultimate regardless of the storage time period (p ≤ 0.001), and microhardness was not affected by the acidic challenge (p = 0.58). After 6 hours of acid exposure, a significant decrease in Raand Rqwas seen for Paradigm MZ100 when compared to the baseline (Rap = 0.032; Rqp = 0.013); however, for Lava Ultimate only Rq decreased (p = 0.021), while Raremained unchanged (p = 0.38). After 24 hours of acid exposure, while Paradigm MZ100 exhibited no additional changes in surface roughness (p ≥ 0.75), Lava Ultimate became rougher (Rap = 0.041; Rqp = 0.014), as confirmed by SEM imaging.
  
  
  CONCLUSIONS
  The acidic scenario tested in the present study changed the surface roughness of the resin composites but not their Vickers microhardness. Moreover, both resin composites seem suitable for use under acidic scenarios, although Paradigm MZ100 showed enhanced stability compared to Lava Ultimate.
authors.affiliation: Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN.|Department of Prosthodontics, Graduate Prosthodontics, IUSD, Indianapolis, IN.
authors.forename: Adriana D
authors.initials: AD
authors.lastname: Backer
authors.affiliation: Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN.|Department of Operative Dentistry, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Eliseu A
authors.initials: EA
authors.lastname: Münchow
authors.affiliation: Department of Biostatistics, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: George J
authors.initials: GJ
authors.lastname: Eckert
authors.affiliation: Department of Cariology, Operative Dentistry and Dental Public Health, IUSD, Indianapolis, IN.
authors.forename: Anderson T
authors.initials: AT
authors.lastname: Hara
authors.affiliation: Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Platt
authors.affiliation: Department of Biomedical and Applied Sciences, Division of Dental Biomaterials, Indiana University School of Dentistry (IUSD), Indianapolis, IN.
authors.forename: Marco C
authors.initials: MC
authors.lastname: Bottino
mesh_terms: D003188:Composite Resins; D017076:Computer-Aided Design; D017266:Dental Prosthesis; D017267:Dental Prosthesis Design; D005750:Gastric Juice / Q000378:metabolism*; D006244:Hardness; D008855:Microscopy, Electron, Scanning; D012117:Resins, Synthetic; D013499:Surface Properties; D015040:Zirconium
chemical_list: D003188:Composite Resins; D012117:Resins, Synthetic; C452079:paradigm MZ100; D015040:Zirconium
keywords: Acid degradation; Bulimia; CAD/CAM; Hardness; Resin composites; Roughness