title: Clinical study to evaluate the wear of natural enamel antagonist to zirconia and metal ceramic crowns.
abstract: BACKGROUND
  Tooth wear is a complex process, which, if not prevented, may adversely affect the integrity of the stomatognathic system. Different restorative dental materials may affect the amount of wear on natural enamel antagonists.
  
  
  OBJECTIVE
  The purpose of this in vivo study was to evaluate and compare the wear of enamel opposing natural enamel, zirconia, and metal ceramic crowns after 1 year.
  
  
  METHODS
  Ten participants between 18 and 35 years of age requiring 2 complete crowns, 1 on either side of maxillary or mandibular molar region, and having healthy natural teeth in the opposing arch were selected. For each participant, 1 monolithic polished zirconia crown and 1 glazed metal ceramic crown were fabricated and cemented. To evaluate the wear of the antagonistic natural enamel (premolar and molar), polyvinyl siloxane impressions were made immediately (baseline) and at 1 year after cementation. The wear of natural enamel against natural enamel was evaluated as the control. The resulting casts were scanned (using a 3D white light scanner), and 3D software was used to calculate the maximum amount of linear wear.
  
  
  RESULTS
  One-way repeated measures ANOVA was conducted to analyze data. Mean ±SD occlusal wear of the antagonistic enamel 1 year after the cementation of metal ceramic crowns was 69.20 ±4.10 μm for premolar teeth and 179.70 ±8.09 μm for molar teeth, whereas for zirconia crowns, it was 42.10 ±4.30 μm for premolar teeth and 127.00 ±5.03 μm for molar teeth. Occlusal wear of natural enamel opposing natural enamel was 17.30 ±1.88 μm in the premolar region and 35.10 ±2.60 μm in the molar region. The Bonferroni post hoc test revealed that the occlusal wear of antagonistic enamel 1 year after the cementation of a metal ceramic crown was significantly higher (P<.001) than that of an opposing zirconia crown or natural enamel.
  
  
  CONCLUSIONS
  Zirconia crowns led to less wear of antagonist enamel than metal ceramic crowns, but more than natural enamel.
authors.affiliation: Former Resident, Department of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Kailas
authors.initials: K
authors.lastname: Mundhe
authors.affiliation: Professor, Department of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Veena
authors.initials: V
authors.lastname: Jain
authors.affiliation: Senior Research Associate, Department of Prosthodontics, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India. Electronic address: gunjan_prostho@yahoo.co.in.
authors.forename: Gunjan
authors.initials: G
authors.lastname: Pruthi
authors.affiliation: Professor, Department of Endodontics and Conservative Dentistry, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Naseem
authors.initials: N
authors.lastname: Shah
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid; D002484:Cementation; D003442:Crowns / Q000009:adverse effects*; D003743:Dental Enamel; D003764:Dental Materials / Q000009:adverse effects*; D003776:Dental Porcelain / Q000009:adverse effects*; D019554:Dental Restoration Wear; D005260:Female; D006801:Humans; D008297:Male; D008963:Molar; D011145:Polyvinyls; D012833:Siloxanes; D019217:Tooth Attrition; D057085:Tooth Wear; D055815:Young Adult; D015040:Zirconium / Q000009:adverse effects*
chemical_list: D003764:Dental Materials; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide