title: Retentive properties of five different luting cements on base and noble metal copings.
abstract: BACKGROUND
  The retention of indirectly fabricated restorations can be compromised by short or over-tapered tooth preparations.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the retentive properties of 5 different luting cements on base and noble metal copings to short and over-tapered preparations.
  
  
  METHODS
  Eighty extracted mandibular premolars were prepared to receive full cast copings with a flat occlusal surface, 33 degrees taper, and 3-mm axial length. Half of the standardized metal copings were cast in an AuAgPd alloy, whereas the other half were cast in an NiCr alloy. Cementation was performed with 5 different luting cements through use of 5 kg of pressure in 90% relative humidity. Specimens were stored in distilled water at 37 degrees C for 24 hours and thermocycled between 5 degrees C and 55 degrees C for 5000 cycles, with a dwell time of 30 seconds. After thermocycling, vertical tensile force was applied in a Zwick universal testing machine with a constant speed of 1 mm/min until separation was noted. A 2-factor analysis of variance was used to analyze the data, with a significance level of alpha =.05.
  
  
  RESULTS
  Mean dislodgement forces for AuAgPd crowns and NiCr crowns were 120.88 N and 143.09 N, respectively, for zinc phosphate cement; 135.45 N and 150.38 N for Principle; 145.88 N and 220.71 N for Meron; 276.85 N and 225.61 N for Avanto; and 300.92 N and 381.02 N for Fuji Plus.
  
  
  CONCLUSIONS
  Within the limitations of this study, Fuji Plus and Avanto showed significantly higher retentive strengths for AuAgPd copings in comparison to the other cements tested (P <.05). The retentive strength of Fuji Plus was significantly higher than those of the other cements tested with NiCr copings (P <.05).
authors.affiliation: Faculty of Dentistry, Marmara University, 80200 Nisantasi, Istanbul, Turkey.
authors.forename: Sule
authors.initials: S
authors.lastname: Ergin
authors.forename: Deniz
authors.initials: D
authors.lastname: Gemalmaz
mesh_terms: D000268:Adhesiveness; D000704:Analysis of Variance; D001641:Bicuspid; D002858:Chromium Alloys / Q000737:chemistry; D000044:Dental Abutments; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D017268:Dental Prosthesis Retention; D005899:Glass Ionomer Cements / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry; D011312:Pressure; D019279:Resin Cements / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D019246:Tooth Preparation; D014867:Water / Q000737:chemistry; D015036:Zinc Phosphate Cement / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D003738:Dental Cements; D005899:Glass Ionomer Cements; D006047:Gold Alloys; D019279:Resin Cements; D014867:Water; D012834:Silver; D010165:Palladium; D015036:Zinc Phosphate Cement