title: Fracture resistance of all-ceramic and metal-ceramic inlays.
abstract: OBJECTIVE
  Metal-ceramic inlay designs were developed to determine if the esthetic qualities of all-ceramic inlays could be duplicated and at the same time improve their strength and stability. The objectives of this study were to: (1) compare the fracture resistance of metal-ceramic inlays with that of all-ceramic inlays; (2) determine the correlation between the degree of preparation taper and fracture resistance; and (3) determine the correlation between marginal gap width and fracture resistance.
  
  
  METHODS
  Inlay preparations were made on 60 Dentoform teeth, with 30 teeth allocated for metal-ceramic inlays and 30 teeth for all-ceramic inlays. Each group was further subdivided into 5-, 10-, and 20-degree taper preparations. Metal-ceramic inlays were fabricated using Goldtech Bio 2000 metal and Ceramco porcelain extending to the margin, while all-ceramic inlays were made from Empress II ceramic. Marginal gap widths were measured at six critical areas after fabrication. The load at failure was measured using an Instron Universal Testing Machine.
  
  
  RESULTS
  The mean fracture load for all-ceramic inlays and metal-ceramic inlays at 5, 10, and 20 degrees was 70+/-40 N, 48+/-37 N, 33+/-7 N, and 40+/-23 N, 29+/-22 N, and 14+/-4 N, respectively. The mean gap width was 105 microm and 126 microm for all-ceramic and metal-ceramic inlays, respectively.
  
  
  CONCLUSIONS
  The mean fracture load for Empress inlays was significantly higher than that for metal-ceramic inlays. Inlays with a 5-degree taper were significantly more fracture resistant than those with a 20-degree taper. There was no relation between marginal gap width and fracture resistance.
authors.affiliation: Department of Prosthodontics, University of Florida College of Dentistry, Gainesville 32610, USA. jesquivel@dental.ufl.edu
authors.forename: J F
authors.initials: JF
authors.lastname: Esquivel-Upshaw
authors.forename: K J
authors.initials: KJ
authors.lastname: Anusavice
authors.forename: M C
authors.initials: MC
authors.lastname: Yang
authors.forename: R B
authors.initials: RB
authors.lastname: Lee
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D002516:Ceramics / Q000737:chemistry*; D003737:Dental Cavity Preparation; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007284:Inlays; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008963:Molar; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D005899:Glass Ionomer Cements; D006047:Gold Alloys; C075815:IPS-Empress ceramic; D016876:Metal Ceramic Alloys; C091610:Protech glass ionomer cement; D019279:Resin Cements; D003776:Dental Porcelain; C058233:Ceramco