title: Effects of different abutment material and surgical insertion torque on the marginal adaptation of an internal conical interface: an in vitro study.
abstract: OBJECTIVE
  To evaluate the marginal adaptation at implant-abutment connection of an implant featuring a conical (45° taper) internal hexagonal abutment with a connection depth of 2.5mm, comparing the performance of two identical abutments of different material (titanium grade-4 and Co-Cr-alloy).
  
  
  METHODS
  Twenty implants (3.75 mm×15 mm) were connected to non-matching abutments (5.5 mm×10 mm) of two different materials (titanium grade-4: n=10; Co-Cr-alloy: n=10). The specimens were separately embedded in epoxylite resin, inside copper cylinders, and submerged without covering the most coronal portion (5 mm) of the fixture. Five specimens per group were stressed simulating a surgical 100 Ncm insertion torque, while the others had no torque simulation. All specimens were subjected to a non-axial static load (100 N) in a universal testing machine, under an angle of 30° with respect to the implant axis. Once 100 N load was reached, low shrinkage self-curing resin was injected inside the cylinders, and load was maintained until complete resin polymerization. Specimens were cut and analyzed with optical and scanning-electron-microscope (SEM) to evaluate the marginal adaptation at the implant-abutment connection. Statistical analysis was performed using one-way ANOVA (p=0.02).
  
  
  RESULTS
  None of the 20 samples failed. The implant-abutment connection was able to guarantee a good optical seal; SEM analysis confirmed the absence of microgaps.
  
  
  CONCLUSIONS
  Within the limits of this study (small sample size, limited time) the marginal adaptation of the implant-abutment connection was not affected by the abutment material nor by the application of surgical insertion torque.
authors.affiliation: Department of Surgical and Morphological Science, Dental School, University of Varese, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Farronato
authors.affiliation: Department of Prosthodontic and Implantology, Fondazione IRCCS Ca' Granda, University of Milan, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Pieroni
authors.affiliation: Department of Surgical and Morphological Science, Dental School, University of Varese, Italy. Electronic address: francescomangano1@mclink.net.
authors.forename: Francesco Guido
authors.initials: FG
authors.lastname: Mangano
authors.affiliation: Department of Prosthodontic and Implantology, Fondazione IRCCS Ca' Granda, University of Milan, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Briguglio
authors.affiliation: Department of Oral Rehabilitation, Istituto Stomatologico Italiano, University of Milan, Italy.
authors.forename: Dino
authors.initials: D
authors.lastname: Re
mesh_terms: D002858:Chromium Alloys; D000044:Dental Abutments; D003722:Dental Alloys; D059605:Dental Implant-Abutment Design / Q000379:methods*; D018772:Dental Marginal Adaptation; D003764:Dental Materials; D066298:In Vitro Techniques; D014025:Titanium; D019415:Torque
chemical_list: D002858:Chromium Alloys; D003722:Dental Alloys; D003764:Dental Materials; D014025:Titanium
keywords: Dental implants; Implant–abutment connection; Marginal adaptation; Microgap