title: A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain.
abstract: OBJECTIVE
  This study was conducted to evaluate clinical validity of a zirconia full-coverage crown by comparing zirconia's wear capacity over antagonistic teeth with that of feldspathic dental porcelain.
  
  
  METHODS
  THE SUBJECT GROUPS WERE DIVIDED INTO THREE GROUPS: the polished feldspathic dental porcelain group (Group 1), the polished zirconia group (Group 2), and the polished zirconia with glazing group (Group 3). Twenty specimens were prepared from each group. Each procedure such as plasticity, condensation, and glazing was conducted according to the manufacturer's manual. A wear test was conducted with 240,000 chewing cycles using a dual-axis chewing simulator. The degree of wear of the antagonistic teeth was calculated by measuring the volume loss using a three-dimensional profiling system and ANSUR 3D software. The statistical significance of the measured degree of wear was tested with a significant level of 5% using one-way ANOVA and the Tukey test.
  
  
  RESULTS
  The degrees of wear of the antagonistic teeth were 0.119 ± 0.059 mm(3) in Group 1, 0.078 ± 0.063 mm(3) in Group 3, and 0.031 ± 0.033 mm(3) in Group 2. Statistical significance was found between Group 1 and Groups 2 and between Group 2 and 3, whereas no statistical significance was found between Group 1 and Group 3.
  
  
  CONCLUSIONS
  Despite the limitations of this study on the evaluation of antagonistic teeth wear, the degree of antagonistic tooth wear was less in zirconia than feldspathic dental porcelain, representing that the zirconia may be more beneficial in terms of antagonistic tooth wear.
authors.affiliation: Advanced Prosthodontics, Graduate School of Clinical Dentistry, Korea University, Seoul, Korea.
authors.forename: Yu-Seok
authors.initials: YS
authors.lastname: Jung
authors.forename: Jae-Whang
authors.initials: JW
authors.lastname: Lee
authors.forename: Yeon-Jo
authors.initials: YJ
authors.lastname: Choi
authors.forename: Jin-Soo
authors.initials: JS
authors.lastname: Ahn
authors.forename: Sang-Wan
authors.initials: SW
authors.lastname: Shin
authors.forename: Jung-Bo
authors.initials: JB
authors.lastname: Huh