Advertisement
Journal of Prosthetic Dentistry

Salvaging an implant with damaged internal threads

  • Burak Yilmaz
    Correspondence
    Corresponding author: Dr Burak Yilmaz, Division of Restorative Sciences and Prosthodontics, The Ohio State University College of Dentistry, 305 W 12th Ave, Columbus, Ohio 43210
    Affiliations
    Associate Professor, Division of Restorative Sciences and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, Ohio
    Search for articles by this author
  • Faye Mascarenhas
    Affiliations
    Resident, Division of Restorative Sciences and Prosthodontics, College of Dentistry, The Ohio State University, Columbus, Ohio
    Search for articles by this author
      Implant prosthetic dentistry is not problem-free, and clinicians face complications including screw loosening, screw fracture, abutment fracture, damaged abutment threads, and damaged implant threads.
      • Goodacre C.
      • Kan J.Y.
      • Rungcharassaeng K.
      Clinical complications of osseointegrated implants.
      • Pipko D.J.
      • Kukunas S.
      • Ismail Y.H.
      Retrofitting a cast dowel-core on salvaged dental implants.
      • Pow E.H.
      • Wat P.Y.
      A technique for salvaging an implant-supported crown with a fractured abutment screw.
      • Imam A.
      • Yilmaz B.
      • Ozcelik T.B.
      • McGlumphy E.A.
      Salvaging an angled implant abutment with damaged internal threads: A clinical report.
      • Yilmaz B.
      • McGlumphy E.
      A technique to salvage a single implant-supported fixed dental prosthesis having a nonretrievable implant screw fragment.
      • Yilmaz B.
      • McGlumphy E.
      A technique to retrieve fractured implant screws.
      Where the internal threads of an implant are damaged, they may become nonrestorable. Some techniques have been reported for salvaging the implant,
      • Pipko D.J.
      • Kukunas S.
      • Ismail Y.H.
      Retrofitting a cast dowel-core on salvaged dental implants.
      • Yilmaz B.
      • McGlumphy E.
      A technique to retrieve fractured implant screws.
      including fabrication of a conventional dowel and core.
      • Pipko D.J.
      • Kukunas S.
      • Ismail Y.H.
      Retrofitting a cast dowel-core on salvaged dental implants.
      • Pow E.H.
      • Wat P.Y.
      A technique for salvaging an implant-supported crown with a fractured abutment screw.
      However, this can cause extensive damage to the implant and may result in the need to remove it. Removal of the implant requires additional surgical procedures, increases cost, and delays restoration of the edentulous space.
      Implant internal threads can be retapped, and an abutment can be secured in the implant with the help of new threads formed with a tapping tool. Retapping threads allows the use of original implant prosthetic parts during the fabrication of a new restoration. This may improve the long-term success of the new restoration and the implant because a favorable implant–abutment connection can be achieved with the use of original parts. In addition, this technique is safer than the conventional post-core fabrication procedure. However, caution should be used during tapping to form proper threads and not break the tapping tool. The fit of screw threads to the retapped threads may also be inferior to a regular, manufactured screw thread-implant internal thread fit. Therefore, the restoration and the implant should be monitored for integrity at follow-up appointments.
      This report describes a procedure for salvaging an implant with damaged internal threads caused by a previously secured prefabricated, threaded root canal post in the implant screw hole (Fig. 1A, B). The loose crown and root canal post were removed. New threads were formed with a tapping tool, and a new crown was fabricated from original parts.
      Figure thumbnail gr1a
      Figure 1A, Periapical radiograph of loose restoration with prefabricated post. B, Intraoral view of loose restoration. C, Frontal view of prefabricated post after removal of loose restoration. D, Implant site after removal of prefabricated post. E, Loose restoration, prefabricated post, and post removal tool. F, Periapical radiograph of ill-fitting healing abutment. G, Thread tapping tool in handle. H, Thread tapping tool in implant. I, Radiograph of tapping tool in implant. J, Radiograph of seated impression post. K, Radiograph of abutment.
      Figure thumbnail gr1bg
      Figure 1A, Periapical radiograph of loose restoration with prefabricated post. B, Intraoral view of loose restoration. C, Frontal view of prefabricated post after removal of loose restoration. D, Implant site after removal of prefabricated post. E, Loose restoration, prefabricated post, and post removal tool. F, Periapical radiograph of ill-fitting healing abutment. G, Thread tapping tool in handle. H, Thread tapping tool in implant. I, Radiograph of tapping tool in implant. J, Radiograph of seated impression post. K, Radiograph of abutment.
      Figure thumbnail gr1hk
      Figure 1A, Periapical radiograph of loose restoration with prefabricated post. B, Intraoral view of loose restoration. C, Frontal view of prefabricated post after removal of loose restoration. D, Implant site after removal of prefabricated post. E, Loose restoration, prefabricated post, and post removal tool. F, Periapical radiograph of ill-fitting healing abutment. G, Thread tapping tool in handle. H, Thread tapping tool in implant. I, Radiograph of tapping tool in implant. J, Radiograph of seated impression post. K, Radiograph of abutment.

      Procedure

      • 1.
        Remove the loose crown with pliers (GC Pliers; GC America) and the prefabricated post with a post removal tool (CYTCO-K; Dentsply Intl) (Fig. 1C-E). Use a tissue punch (Salvin Dental Specialties) to expose the implant platform (Tapered Screw Vent; Zimmer Dental), which was completely covered with gingiva. Control the bleeding with a hemostatic agent (Viscostat; Ultradent Products Inc).
      • 2.
        Attempt to screw a healing abutment (Zimmer Dental) to the implant to see whether it engages the internal threads of the implant. Make a periapical radiograph to evaluate whether the abutment is completely seated (Fig. 1F).
      • 3.
        If the abutment does not engage the implant’s internal threads and the misfit between the abutment and implant can be radiographically confirmed, use a tapping tool (model 172UWF thread tap; Zimmer Dental) to form new threads in the internal surface of the implant (Fig. 1G).
        • Pow E.H.
        • Wat P.Y.
        A technique for salvaging an implant-supported crown with a fractured abutment screw.
        Remove the head of the tool if it is too large to use between the adjacent teeth (Fig. 1H).
      • 4.
        Use the tapping tool in a clockwise direction, and each time resistance is felt, remove the tool in a counter clockwise direction. Exercise caution during retapping and rinse the internal surface of the implant with water after each attempt. Repeat the procedure until a proper depth is achieved for an impression post to completely seat (Fig. 1I).
      • 5.
        Evaluate the impression post (Zimmer Dental) on the implant, and make a radiograph to determine whether the impression post is completely seated on the implant platform (Fig. 1J).
      • 6.
        Once the impression post is completely and securely seated, make a definitive impression with polyvinyl siloxane impression material (Aquasil Ultra; Dentsply Caulk) for the fabrication of a definitive crown on the implant with the new internal threads (Fig. 1K, Fig. 2).
        Figure thumbnail gr2
        Figure 2Intraoral view of definitive crown.

      References

        • Goodacre C.
        • Kan J.Y.
        • Rungcharassaeng K.
        Clinical complications of osseointegrated implants.
        J Prosthet Dent. 1999; 81: 537-552
        • Pipko D.J.
        • Kukunas S.
        • Ismail Y.H.
        Retrofitting a cast dowel-core on salvaged dental implants.
        J Prosthodont. 2004; 13: 52-54
        • Pow E.H.
        • Wat P.Y.
        A technique for salvaging an implant-supported crown with a fractured abutment screw.
        J Prosthet Dent. 2006; 95: 169-170
        • Imam A.
        • Yilmaz B.
        • Ozcelik T.B.
        • McGlumphy E.A.
        Salvaging an angled implant abutment with damaged internal threads: A clinical report.
        J Prosthet Dent. 2013; 109: 287-290
        • Yilmaz B.
        • McGlumphy E.
        A technique to salvage a single implant-supported fixed dental prosthesis having a nonretrievable implant screw fragment.
        J Oral Implantol. 2013; 39: 81-83
        • Yilmaz B.
        • McGlumphy E.
        A technique to retrieve fractured implant screws.
        J Prosthet Dent. 2011; 105: 137-138