Written by Carlos Boudet, DDS Thursday, 13 March 2014 12:40
A broken abutment screw is an unwanted complication; however, when it happens, it could also be your chance to be a hero with your implant patients.
Screw loosening,1-3 which can lead to screw breakage, is seen infrequently in today’s dental practices but was seen more often in the earlier years of implant placement. It has been this author’s experience that this was usually associated with the external hex prosthetic connection.4 This challenge led other implant manufacturers to design internal connections5,6 that were more stable and would prevent the problem.
If a screw loosens, and the problem is not corrected early, it can break in one of 2 ways: the “good” way or the “nasty” way. The good way is when the threads are not binding, and the fragment is loose; this allows for easier retrieval. The nasty way is when the fragment threads bind due to deformation, structural damage, or thread locking compounds; this requires extreme care and effort for retrieval. It is easy enough for most of us to inspect the case to determine which of these situations is present.
The following case report describes a simple technique used to remove a broken screw and successfully repair the case.
Diagnosis and Treatment Planning
A new patient came to our office with an implant-related problem. A visual inspection and a periapical radiograph (Figure 1) showed a 4-unit bridge retained by implants placed in the maxillary central incisor positions (teeth Nos. 8 and 9, respectively). The implants were placed extremely deep7 under the bone and needed 7.0-mm long standard abutments to bring the connection to the correct level (about one mm subgingival). The implants were also placed palatal to the normal location (Figure 2). The bridge was screw-retained, and it was loose. Furthermore, the radiograph showed that the screw that attached to the left implant was broken inside the implant. The abutment had fallen out and the patient brought it in his hand, along with the broken screw (Figure 3).
There are several screw removal kits available commercially from different manufacturers;8,9 however, after obtaining advice from a knowledgeable prosthodontist colleague, it was clear that the preferred way to remove a broken screw utilized some commonly available instruments readily available in the dental office. The tools needed are (1) a sharp, pointed endodontic spreader or explorer; (2) good magnification (loupes or a microscope); and (3) a small, straight hemostat.
The loose bridge was removed by removing the screw that secured the bridge to the abutment. The soft tissue had completely covered the implant. The implants were identified as Brånemark (regular diameter, external hex) and the replacement screws were then ordered. Next, the implant was uncovered using the laser (Waterlase [BIOLASE]). Then, the broken screw was visualized using an OPMI microscope (ZEISS). (Please note that a diode laser and magnification loupes would also work nicely). The screw was loose, which meant that there was an excellent chance that it could be retrieved. The broken screw fragment was slowly backed out; this was done by placing the sharp point of an explorer on the top of the broken screw and moving it in a counterclockwise fashion. Since there was no friction on the broken screw, it was backed out until it could be grabbed securely by a small, straight hemostat, then carefully turned until it was removed. Both abutment screws were replaced with new screws, and the screws were then torqued to specifications. The screw-retained fixed partial denture was seated over the abutments and tightened to specifications.
A periapical radiograph of the repaired prosthesis is shown in Figure 4.
Dental implant-supported prostheses have been used for decades now, and some of them are having problems. One of those problems is screw loosening and breakage. The simple technique demonstrated here utilized common instruments to retrieve a broken abutment screw and allowed the successful repair and continued use of a screw-retained fixed partial denture for a very grateful patient.
- Goodacre CJ, Bernal G, Rungcharassaeng K, et al. Clinical complications with implants and implant prostheses. J Prosthet Dent. 2003;90:121-132.
- Jung RE, Pjetursson BE, Glauser R, et al. A systematic review of the 5-year survival and complication rates of implant-supported single crowns. Clin Oral Implants Res. 2008;19:119-130.
- Kreissl ME, Gerds T, Muche R, et al. Technical complications of implant-supported fixed partial dentures in partially edentulous cases after an average observation period of 5 years. Clin Oral Implants Res. 2007;18:720-726.
- Kitagawa T, Tanimoto Y, Odaki M, et al. Influence of implant/abutment joint designs on abutment screw loosening in a dental implant system. J Biomed Mater Res B Appl Biomater. 2005;75:457-463.
- Niznick G. The implant abutment connection: the key to prosthetic success. Compendium. 1991;12:932-938.
- Khraisat A, Stegaroiu R, Nomura S, et al. Fatigue resistance of two implant/abutment joint designs. J Prosthet Dent. 2002;88:604-610.
- Kan JY, Rungcharassaeng K. Immediate placement and provisionalization of maxillary anterior single implants: a surgical and prosthodontic rationale. Pract Periodontics Aesthet Dent. 2000;12:817-824.
- 3i Implant Innovations. Information and Instructions: Screw Removing Instrument. Bulletin IIS032 Rev C; February 1998. dentalmax.com.ar/pdf/biomet/instrumental/kit/kit_tornillo_fracturado_art628_screw_removing_in-strument.pdf. Accessed November 12, 2013.
- Rhein83 USA. Broken Implant Screw Extractor Kit. Product Information. rhein83usa.com/Prd_ScrewExtractorKit.aspx. Accessed November 12, 2013.
Disclosure: Dr. Boudet reports no disclosures.
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