title: Surface roughness of orthodontic band cements with different compositions.
abstract: OBJECTIVE
  The present study evaluated comparatively the surface roughness of four orthodontic band cements after storage in various solutions.
  
  
  METHODS
  Eight standardized cylinders were made from 4 materials: zinc phosphate cement (ZP), compomer (C), resin-modified glass ionomer cement (RMGIC) and resin cement (RC). Specimens were stored for 24 h in deionized water and immersed in saline (pH 7.0) or 0.1 M lactic acid solution (pH 4.0) for 15 days. Surface roughness readings were taken with a profilometer (Surfcorder SE1200) before and after the storage period. Data were analyzed by two-way ANOVA and Tukey's test (comparison among cements and storage solutions) or paired t-test (comparison before and after the storage period) at 5% significance level.
  
  
  RESULTS
  The values for average surface roughness were statistically different (p<0.001) among cements at both baseline and after storage. The roughness values of cements in a decreasing order were ZP>RMGIC>C>R (p<0.001). After 15 days, immersion in lactic acid solution resulted in the highest surface roughness for all cements (p<0.05), except for the RC group (p>0.05). Compared to the current threshold (0.2 µm) related to biofilm accumulation, both RC and C remained below the threshold, even after acidic challenge by immersion in lactic acid solution.
  
  
  CONCLUSIONS
  Storage time and immersion in lactic acid solution increased the surface roughness of the majority of the tested cements. RC presented the smoothest surface and it was not influenced by storage conditions.
authors.affiliation: Dental School, Federal University of Pelotas, Pelotas, RS, Brazil.
authors.forename: Françoise Hélène
authors.initials: FH
authors.lastname: van de Sande
authors.forename: Adriana Fernandes da
authors.initials: AF
authors.lastname: Silva
authors.forename: Douver
authors.initials: D
authors.lastname: Michelon
authors.forename: Evandro
authors.initials: E
authors.lastname: Piva
authors.forename: Maximiliano Sérgio
authors.initials: MS
authors.lastname: Cenci
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
mesh_terms: D000704:Analysis of Variance; D020770:Compomers / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D007101:Immersion; D019344:Lactic Acid / Q000737:chemistry; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D015036:Zinc Phosphate Cement / Q000737:chemistry
chemical_list: D020770:Compomers; D003738:Dental Cements; D005899:Glass Ionomer Cements; D019279:Resin Cements; D019344:Lactic Acid; D015036:Zinc Phosphate Cement