title: Comparison of fracture resistance of pressable metal ceramic custom implant abutment with a commercially fabricated CAD/CAM zirconia implant abutment.
abstract: BACKGROUND
  The predictable nature of the hot pressing ceramic technique has several applications, but no study was identified that evaluated its application to the fabrication of custom implant abutments.
  
  
  OBJECTIVE
  The purpose of this study was to compare the fracture resistance of an experimentally designed pressable metal ceramic custom implant abutment (PR) with that of a duplicate zirconia abutment (ZR).
  
  
  METHODS
  Two groups of narrow platform (NP) (Nobel Replace) implant abutment specimens were fabricated (n=10). The experimental abutment (PR) had a metal substructure cast with ceramic alloy (Lodestar) and veneered with leucite pressable glass ceramic (InLine PoM). Each PR abutment was individually scanned and 10 duplicate CAD/CAM ZR abutments were fabricated for the control group. Ceramic crowns (n=20) with the average dimensions of a human lateral incisor were pressed with lithium disilicate glass ceramic (IPS e.max Press) and bonded on the abutments with a resin luting agent (Multilink Automix). The specimens were subjected to thermocycling, cyclic loading, and finally static loading to failure with a computer-controlled Universal Testing Machine. An independent t test (1 sided) determined whether the mean values of the fracture load differed significantly (α=.05) between the 2 groups.
  
  
  RESULTS
  No specimen failed during cyclic loading. Upon static loading, the mean (SD) load to failure was significantly higher for the PR group (525.89 [143.547] N) than for the ZR group (413.70 [35.515] N) for internal connection narrow platform bone-level implants (P=.025). Failure was initiated at the screw and internal connection level for both groups.
  
  
  CONCLUSIONS
  It is possible to fabricate PR abutments that are stronger than ZR abutments for Nobel Biocare internal connection NP bone-level implants. The screw and the internal connection are the weak links for both groups.
authors.affiliation: Private practice, Athens, Greece. Electronic address: protomaria@gmail.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Protopapadaki
authors.forename: Edward A
authors.initials: EA
authors.lastname: Monaco
authors.forename: Hyeong-Il
authors.initials: HI
authors.lastname: Kim
authors.forename: Elaine L
authors.initials: EL
authors.lastname: Davis
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D015040:Zirconium / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D003764:Dental Materials; C508050:IPS e.max Press; D016876:Metal Ceramic Alloys; D019279:Resin Cements; C493120:lithia disilicate; C502351:multilink adhesive system; D003776:Dental Porcelain; C078519:leucite; C023506:Glass ceramics; D015040:Zirconium; C028541:zirconium oxide