title: A comparison of two soldering techniques on the misfit of bar-retained implant-supported overdentures.
abstract: OBJECTIVE
  This study was conducted to measure and compare the effect of the soldering method (torch soldering or ceramic furnace soldering) used for soldering bars to bar-retained, implant-supported overdentures on the fit between the bar gold cylinder and implant transgingival abutment.
  
  
  METHODS
  Thirty-two overdenture implant bars were manufactured and screw retained into two Bränemark implants, which were attached to a cow rib. The bars were randomly distributed in two groups: a torch-soldering group and a porcelain-furnace soldering group. Then all bars were cut and soldered using a torch and a ceramic furnace. The fit between the bar gold cylinders and implant transgingival abutments was measured with a light microscope on the opposite side to the screw tightening side before and after the bar soldering procedure. The data obtained were statistically processed for paired and independent data.
  
  
  RESULTS
  The average misfit for all bars before soldering was 33.83 to 54.04 μm. After cutting and soldering the bars, the misfit increased up to a range of 71.74 to 78.79 μm. Both before and after the soldering procedure, the bars soldered using a torch showed a higher misfit when compared to the bars soldered using a porcelain furnace. After the soldering procedure, the misfit was slightly lower on the left side of the bars, which had been soldered using a ceramic furnace.
  
  
  CONCLUSIONS
  According to our data, the soldering of bars using the torch or furnace oven soldering techniques does not improve the misfit of one-piece cast bars on two implants. The lower misfit was obtained using the porcelain furnace soldering technique.
authors.affiliation: Department of Prosthodontics and Occlusion, School of Dentistry, University of Oviedo, Oviedo, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Alvarez
authors.forename: Pedro
authors.initials: P
authors.lastname: Lafita
authors.forename: Hector
authors.initials: H
authors.lastname: de Llanos
authors.forename: Angel
authors.initials: A
authors.lastname: Gago
authors.forename: Aritza
authors.initials: A
authors.lastname: Brizuela
authors.forename: Joseba J
authors.initials: JJ
authors.lastname: Ellacuria
mesh_terms: D000818:Animals; D002417:Cattle; D059605:Dental Implant-Abutment Design; D018772:Dental Marginal Adaptation; D019094:Dental Prosthesis, Implant-Supported; D012994:Dental Soldering / Q000295:instrumentation / Q000379:methods*; D003781:Denture Retention / Q000295:instrumentation*; D003828:Denture, Overlay; D004867:Equipment Design; D006047:Gold Alloys / Q000737:chemistry; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry; D011897:Random Allocation; D013499:Surface Properties
chemical_list: D006047:Gold Alloys; D010165:Palladium
keywords: Misfit; ceramic furnace; light microscope; torch; welding