title: Vickers hardness studies of calcium oxalate monohydrate and brushite urinary stones.
abstract: OBJECTIVE
  To measure the hardness of two types of urinary stones: calcium oxalate monohydrate (COM; CaC2O4 . H2O) and dicalcium phosphate dihydrate (brushite; CaHPO4 . 2H2O).
  
  
  METHODS
  The composition of 28 calcium oxalate monohydrate and 22 brushite stones was characterized by infrared spectroscopy (FT-IR). Stone specimens were embedded in crystallographic resin, polished, and subjected to indentation tests using a Vickers tester. The hardness was calculated from measuring the diagonal lengths of the residual indentation on the specimen using the appropriate equation.
  
  
  RESULTS
  The COM stones showed hardness values ranging from 15.3 to 64.2 HV with a mean of 35.8 +/- 13.3, while brushite stones ranged from 10.1 to 46.1 HV with a mean of 26.5 +/- 15.1. The results of ANOVA showed that there were significant differences (P < 0.05) between the two stone types.
  
  
  CONCLUSIONS
  Calcium oxalate monohydrate stones exhibited greater hardness than brushite stones when assessed with Vickers studies.
authors.affiliation: Department of Materials Science, University of Patras, Patras, Greece.
authors.forename: N
authors.initials: N
authors.lastname: Bouropoulos
authors.forename: D E
authors.initials: DE
authors.lastname: Mouzakis
authors.forename: G
authors.initials: G
authors.lastname: Bithelis
authors.forename: E
authors.initials: E
authors.lastname: Liatsikos
mesh_terms: D002129:Calcium Oxalate / Q000032:analysis*; D002130:Calcium Phosphates / Q000032:analysis*; D006244:Hardness; D006801:Humans; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared; D014545:Urinary Calculi / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D002130:Calcium Phosphates; D002129:Calcium Oxalate; C494366:calcium phosphate, dibasic, dihydrate