title: Assessment of the stress transmitted to dental implants connected to screw-retained bars using different casting techniques.
abstract: Passive fit of the prosthetic superstructure is important to avoid complications; however, evaluation of passive fit is not possible using conventional procedures. Thus, the aim of this study was to check and locate mechanical stress in bar restorations fabricated using two casting techniques. Fifteen patients received four implants in the interforaminal region of the mandible, and a bar was fabricated using either the cast-on abutment or lost-wax casting technique. The fit accuracy was checked according to the Sheffield's test criteria. Measurements were recorded on the master model with a gap-free, passive fit using foil strain gauges both before and after tightening the prosthetic screws. Data acquisition and processing was analyzed with computer software and submitted to statistical analysis (ANOVA). The greatest axial distortion was at position 42 with the cast-on abutment technique, with a mean distortion of 450 μm/m. The lowest axial distortion occurred at position 44 with the lost-wax casting technique, with a mean distortion of 100 μm/m. The minimal differences between the means of axial distortion do not indicate any significant differences between the techniques (P = 0.2076). Analysis of the sensor axial distortion in relation to the implant position produced a significant difference (P < 0.0001). Significantly higher measurements were recorded in the axial distortion analysis of the distal sensors of implants at the 34 and 44 regions than on the mesial positions at the 32 and 42 regions (P = 0.0481). The measuring technique recorded axial distortion in the implant-supported superstructures. Distortions were present at both casting techniques, with no significant difference between the sides.
authors.affiliation: 1  Department of Prosthodontics and Biomaterials, Centre for Implantology, University Hospital RWTH Aachen, Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Haselhuhn
authors.forename: Juliana
authors.initials: J
authors.lastname: Marotti
authors.forename: Pedro
authors.initials: P
authors.lastname: Tortamano
authors.forename: Claudia
authors.initials: C
authors.lastname: Weiss
authors.forename: Lubna
authors.initials: L
authors.lastname: Suleiman
authors.forename: Stefan
authors.initials: S
authors.lastname: Wolfart
mesh_terms: D000044:Dental Abutments; D003724:Dental Arch / Q000473:pathology; D003735:Dental Casting Technique; D015921:Dental Implants; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D019094:Dental Prosthesis, Implant-Supported; D003781:Denture Retention / Q000295:instrumentation*; D006801:Humans; D008334:Mandible / Q000473:pathology; D012984:Software; D013314:Stress, Mechanical; D019415:Torque; D014885:Waxes / Q000737:chemistry
chemical_list: D015921:Dental Implants; D014885:Waxes