title: The wear of polished and glazed zirconia against enamel.
abstract: BACKGROUND
  The wear of tooth structure opposing anatomically contoured zirconia crowns requires further investigation.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to measure the roughness and wear of polished, glazed, and polished then reglazed zirconia against human enamel antagonists and compare the measurements to those of veneering porcelain and natural enamel.
  
  
  METHODS
  Zirconia specimens were divided into polished, glazed, and polished then reglazed groups (n=8). A veneering porcelain (Ceramco3) and enamel were used as controls. The surface roughness of all pretest specimens was measured. Wear testing was performed in the newly designed Alabama wear testing device. The mesiobuccal cusps of extracted molars were standardized and used as antagonists. Three-dimensional (3D) scans of the specimens and antagonists were obtained at baseline and after 200 000 and 400 000 cycles with a profilometer. The baseline scans were superimposed on the posttesting scans to determine volumetric wear. Data were analyzed with a 1-way ANOVA and Tukey Honestly Significant Difference (HSD) post hoc tests (α=.05)
  
  
  RESULTS
  Surface roughness ranked in order of least rough to roughest was: polished zirconia, glazed zirconia, polished then reglazed zirconia, veneering porcelain, and enamel. For ceramic, there was no measureable loss on polished zirconia, moderate loss on the surface of enamel, and significant loss on glazed and polished then reglazed zirconia. The highest ceramic wear was exhibited by the veneering ceramic. For enamel antagonists, polished zirconia caused the least wear, and enamel caused moderate wear. Glazed and polished then reglazed zirconia showed significant opposing enamel wear, and veneering porcelain demonstrated the most.
  
  
  CONCLUSIONS
  Within the limitations of the study, polished zirconia is wear-friendly to the opposing tooth. Glazed zirconia causes more material and antagonist wear than polished zirconia. The surface roughness of the zirconia aided in predicting the wear of the opposing dentition.
authors: Department of Prosthodontics, School of Dentistry, University of Alabama at Birmingham, Birmingham, AL, USA.
authors: Sridhar
authors: S
authors: Janyavula
authors: Nathaniel
authors: N
authors: Lawson
authors: Nathaniel
authors: N
authors: Lawson
authors: Deniz
authors: D
authors: Cakir
authors: Preston
authors: P
authors: Beck
authors: Lance C
authors: LC
authors: Ramp
authors: John O
authors: JO
authors: Burgess
mesh_terms: D000704:Analysis of Variance; D020099:Coated Materials, Biocompatible; D003442:Crowns; D003743:Dental Enamel / Q000502:physiology; D003775:Dental Polishing; D003776:Dental Porcelain; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis / Q000295:instrumentation*; D003801:Dental Veneers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008422:Materials Testing; D008963:Molar; D018709:Statistics, Nonparametric; D013499:Surface Properties; D057085:Tooth Wear; D015040:Zirconium
chemical_list: D020099:Coated Materials, Biocompatible; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide