title: In vitro study of the effect of three hydrogen peroxide concentrations on the corrosion behavior and surface topography of alumina-reinforced dental ceramic.
abstract: OBJECTIVE
  This in vitro investigation studied the effect of three hydrogen peroxide (HP) concentrations (30%, 35%, 38% v/v) at two time intervals (1 and 2 hours) on the corrosion behavior and surface topography of a dental ceramic.
  
  
  METHODS
  A total of 62 Vitadur Alpha discs were constructed following manufacturer instructions. Specimens were divided into four main groups (n = 8). Group 1 (control): specimens were immersed in 4% acetic acid for 18 hours at 80°C. Groups 2, 3, and 4: specimens were immersed in 30%, 35%, and 38% HP concentrations, respectively. Each of the three groups was divided into two subgroups (a and b) according to the immersion time (1 and 2 hours, respectively). Specimens of subgroup a were further immersed in 4% acetic acid for 18 hours at 80°C and were designated as subgroup c. The corrosion behavior of the ceramic specimens were tested by solution analysis using the atomic absorption method, weight loss percent, and corrosion rate. Surface topography was investigated by surface roughness (Ra) measurements and scanning electron microscopy (SEM). Results were statistically analyzed.
  
  
  RESULTS
  There was a significant increase for ions leached with the increase in time of immersion for all ions at 35% and 38% HP, while at 30% HP, ions of K(+) , Al(3+) , and Si(4+) did not increase significantly with time. The results also showed that at a fixed time of immersion, all ions released were dependent on the increase of HP concentration except for Al(3+) ions (p < 0.05). The combined treatment of specimens with HP followed by acetic acid had a significant effect on the increase of ions leached (p < 0.05). The surface roughness values for all specimens increased significantly with time of immersion as well as with the increase in concentration of HP (p < 0.05). These results were confirmed with SEM.
  
  
  CONCLUSIONS
  The amount of released ions is directly proportional to HP concentration and time of immersion. Specimens exposed to both HP and acetic acid showed increased weight loss and a higher corrosion rate than those exposed to acetic acid only. Surface roughness values were time and HP concentration dependent.
authors.affiliation: Department of Fixed Prosthodontics, Faculty of Dentistry, Minia University, Minia, Egypt. manalrafei@yahoo.com
authors.forename: Manal R
authors.initials: MR
authors.lastname: Abu-Eittah
authors.forename: Mona H
authors.initials: MH
authors.lastname: Mandour
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000535:Aluminum / Q000032:analysis; D000537:Aluminum Oxide; D002118:Calcium / Q000032:analysis; D003343:Corrosion; D003776:Dental Porcelain / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011188:Potassium / Q000032:analysis; D012825:Silicon / Q000032:analysis; D012964:Sodium / Q000032:analysis; D013499:Surface Properties; D013997:Time Factors
chemical_list: D007477:Ions; C483027:vitadur alpha; D003776:Dental Porcelain; D012964:Sodium; D006861:Hydrogen Peroxide; D000535:Aluminum; D000537:Aluminum Oxide; D019342:Acetic Acid; D011188:Potassium; D002118:Calcium; D012825:Silicon