title: Complications with computer-aided designed/computer-assisted manufactured titanium and soldered gold bars for mandibular implant-overdentures: short-term observations.
abstract: BACKGROUND
  Implant-overdentures supported by rigid bars provide stability in the edentulous atrophic mandible. However, fractures of solder joints and matrices, and loosening of screws and matrices were observed with soldered gold bars (G-bars). Computer-aided designed/computer-assisted manufactured (CAD/CAM) titanium bars (Ti-bars) may reduce technical complications due to enhanced material quality.
  
  
  OBJECTIVE
  To compare prosthetic-technical maintenance service of mandibular implant-overdentures supported by CAD/CAM Ti-bar and soldered G-bar.
  
  
  METHODS
  Edentulous patients were consecutively admitted for implant-prosthodontic treatment with a maxillary complete denture and a mandibular implant-overdenture connected to a rigid G-bar or Ti-bar. Maintenance service and problems with the implant-retention device complex and the prosthesis were recorded during minimally 3-4 years. Annual peri-implant crestal bone level changes (ΔBIC) were radiographically assessed.
  
  
  RESULTS
  Data of 213 edentulous patients (mean age 68 ± 10 years), who had received a total of 477 tapered implants, were available. Ti-bar and G-bar comprised 101 and 112 patients with 231 and 246 implants, respectively. Ti-bar mostly exhibited distal bar extensions (96%) compared to 34% of G-bar (p < .001). Fracture rate of bars extensions (4.7% vs 14.8%, p < .001) and matrices (1% vs 13%, p < .001) was lower for Ti-bar. Matrices activation was required 2.4× less often in Ti-bar. ΔBIC remained stable for both groups.
  
  
  CONCLUSIONS
  Implant overdentures supported by soldered gold bars or milled CAD/CAM Ti-bars are a successful treatment modality but require regular maintenance service. These short-term observations support the hypothesis that CAD/CAM Ti-bars reduce technical complications. Fracture location indicated that the titanium thickness around the screw-access hole should be increased.
authors.affiliation: Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland.
authors.forename: Joannis
authors.initials: J
authors.lastname: Katsoulis
authors.forename: Julia
authors.initials: J
authors.lastname: Wälchli
authors.forename: Simone
authors.initials: S
authors.lastname: Kobel
authors.forename: Hadi
authors.initials: H
authors.lastname: Gholami
authors.forename: Regina
authors.initials: R
authors.lastname: Mericske-Stern
mesh_terms: D000368:Aged; D017076:Computer-Aided Design; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D012994:Dental Soldering; D003780:Denture Repair; D003781:Denture Retention / Q000295:instrumentation*; D003828:Denture, Overlay; D005260:Female; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D007575:Jaw, Edentulous / Q000534:rehabilitation; D008297:Male; D014025:Titanium / Q000737:chemistry; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants; D006047:Gold Alloys; D014025:Titanium
keywords: CAD/CAM technology; complications; gold; implant-overdenture; maintenance service; rigid bar; titanium