Management of a Fractured Implant Abutment Screw:
A Clinical Report
Ceyhun Canpolat, DDS, PhD,1 Zeynep Özkurt-Kayahan, DDS, PhD,2 & Ender Kazazoğlu, DDS, PhD3
1
Assistant Professor, Department of Prosthodontics, Yeditepe University, Faculty of Dentistry, Istanbul, Turkey
Associate Professor, Department of Prosthodontics, Yeditepe University, Faculty of Dentistry, Istanbul, Turkey
3
Professor, Department of Prosthodontics, Yeditepe University, Faculty of Dentistry, Istanbul, Turkey
2
Keywords
Implant; screw fracture; management;
complication.
Correspondence
Zeynep Özkurt-Kayahan, Department of
Prosthodontics, Yeditepe University, Faculty
of Dentistry, Bağdat cad. No: 238, 34728
Goztepe, Istanbul, Turkey.
E-mail: zeynepozkurt@hotmail.com
The authors deny any conflicts of interest.
Accepted July 10, 2013
doi: 10.1111/jopr.12111
Abstract
In an abutment screw fracture, it is generally a challenge for the clinician to remove
fractured fragments. In some cases, the screw cannot be removed, and alternative
solutions should be considered. This clinical report describes the replacement of a
ball attachment with a fractured screw, which was impossible to retrieve, with a
cast dowel with ball attachment. The patient who presented to the Department of
Prosthodontics, Yeditepe University, Faculty of Dentistry was a 65-year-old woman,
wearing a mandibular complete denture supported by two implants for 4 years. She
complained about the loss of retention of the denture because of the fractured abutment
screw, and it was found that another dentist had previously tried to retrieve the fractured
screw with no success. It was decided to construct a cast dowel with ball attachment to
improve retention without sacrificing the implant. The interior of the implant and the
fractured screw were machined with a rotating instrument. An impression was taken
with a metal strip and silicone-based materials. In the laboratory, a stone die was
generated from the impression, and a custom-made cast dowel with ball attachment
was constructed. It was then cemented with glass ionomer cement and connected to
the denture with the direct method. The alternative procedure described in this clinical
report was successful for the removal of the fractured abutment screw and use of the
existing denture.
Dental implants are an effective, reliable, and predictable
prosthodontic treatment option for partially and completely
edentulous patients.1,2 Despite a high success rate of 97% to
99%,3,4 technical and biological problems may be encountered.
Biological complications include peri-implant radiolucencies,
peri-implantitis, and radiographic signs of loss of osseointegration. Technical complications include loss of retention, screw
loosening, and fractures of porcelain/framework/screws.5
Abutment screw fracture is an uncommon (range from 0.5%
to 8%)6 but challenging technical complication in implantretained restorations and may occur due to bruxism, unfavorable superstructure, overloading, malfunction, premature occlusal contacts, metal fatigue after screw loosening, and component misfit.6-9
A fractured abutment screw must be removed without damage to the implant body to be replaced by a new abutment, so the
implant will still be able to retain the prosthesis.10 The success
of removal depends on the location of the screws. If fracture occurs above the head of the implant, the screw can be removed
successfully with hemostats; however, if fracture occurs below the head of the implant, other special removal systems,
such as Retrieval Instruments (Nobel Biocare, Zurich, Switzer402
land), Neo Screw Remover Kit (Neobiotech, Seoul, Korea),
and Implant Repair Kit (ITI, Waldenburg, Switzerland), should
be used.11-13 If these systems are not available, other methods for retrieving fractured abutment screws may be tried.11-18
Although in the authors’ opinion, removing the fractured part
successfully without any damage to the internal threads of the
implant and screwing a new abutment is the best solution, the
attempts may be unsuccessful in some cases. The aim of this
report was to describe an alternative method to remove a fractured screw without sacrificing the implant and to maintain the
use of an existing mandibular overdenture using conventional
techniques.
Clinical report
A 65-year-old female patient presented to the Department of
Prosthodontics, Yeditepe University, Faculty of Dentistry. She
had been wearing a maxillary complete denture and a mandibular overdenture supported by two implants for 4 years. She complained about the loss of retention of the overdenture because
of the fractured abutment screw whose apical part remained
threaded into the implant. Upon clinical examination, it was
C 2014 by the American College of Prosthodontists
Journal of Prosthodontics 23 (2014) 402–405
Fractured Abutment Screw
Canpolat et al
Figure 1 Fractured abutment screw.
Figure 5 Cast dowel with ball attachment.
Figure 2 (A) Dowel space, (B) metal strip, (C) impression.
Figure 6 (A) Dowel in place, (B) radiographic image of the dowel.
Figure 3 Final impression.
Figure 7 (A) Cast dowel and ball housing, (B, C) ball housing try-in.
Figure 4 (A) Impression of the existing ball attachment, (B) cold-curing
acrylic replica.
found that another dentist had tried to retrieve the fractured
screw but was not successful (Fig 1). The remaining part of the
fractured screw was very small, far from the implant neck, and
almost impossible to remove. Since the fractured screw and the
inner walls of the implant had been machined and damaged
during previous removal attempts, it was impossible to retrieve
the fractured screw. Therefore, the only solution seemed to
be placement of a new implant. Both implants were osseointegrated without any sign of peri-implantitis. The patient and
the clinician were not willing to sacrifice the implant and to
C 2014 by the American College of Prosthodontists
Journal of Prosthodontics 23 (2014) 402–405
403
Fractured Abutment Screw
Canpolat et al
Figure 8 A hole was opened for excess acrylic in the existing mandibular
overdenture.
Snap vks 1.7; Bredent, Senden, Germany) was fabricated in the
laboratory, using chrome-cobalt alloy (MESA, Brescia, Italy;
Fig 5). In the next appointment, a cast dowel with ball attachment was tried in the site for proper fit. The dowel was then luted
with glass ionomer cement (Meron; VOCO GmbH, Cuxhaven,
Germany; Fig 6). The ball housing (Fig 7) was fixed in the
existing mandibular overdenture with the direct method using
self-curing acrylic resin material (Meliodent; Heraeus Kulzer
GmbH, Hanau, Germany). Excess acrylic came out through the
previously opened hole in the denture (Fig 8). After polymerization of the acrylic, the overdenture was removed, trimmed,
and polished. The overdenture was checked for retention, and
proper occlusal relationship with the existing maxillary complete denture was obtained.
The results are satisfactory both for the patient and for the
clinician. After a 15-month follow-up, continued stabilization
of the dowel, implant, and dentures was observed (Fig 9).
Discussion
Figure 9 Patient with restored ball attachment after 15 months
follow-up.
construct a new treatment plan with additional implants. When
the clinician was questioned about any other possible solution,
it was decided to produce a cast metallic dowel with ball attachment to improve retention without sacrificing the implant
and the existing overdenture.
The implant interior and the remaining fractured screw were
machined with a high-speed handpiece (320,000 rpm) under water cooling and a diamond bur (Super Coarse, 180 to
200 µm, No:544; Acurata GmbH, Thurmansbang, Germany).
The running handpiece was removed from the implant every few seconds so there was adequate water cooling inside the implant. After radiographs of the dowel space were
taken (Fig 2A), an impression was taken with a metal strip
(Fig 2B) and poly(vinyl siloxane) (PVS) impression material (Fig 2C; Express XT Light Body Quick and Express XT
Penta Putty, 3M ESPE, Neuss, Germany). After polymerization
(Fig 3), another impression was taken with PVS material to
construct a similar attachment above the dowel that would be
a reproduction of the ball attachment of the sound implant
(Fig 4A). After the negative space of the existing ball attachment was filled with cold-curing acrylic material (Meliodent;
Heraeus Kulzer GmbH, Hanau, Germany) to determine the
height, a stone die was generated from the impression (Fig 4B).
A custom-made cast dowel with ball attachment (Vario-Kugel
404
There is only one article in the literature presenting a technique
of converting the screw chamber into a dowel space and constructing a dowel-core and crown restoration.18 However, the
presented case describes a similar solution to abutment screw
fracture complication of an implant-retained overdenture. One
possible explanation for the fracture was assumed to be the
unrecognized loosening of the screw caused by nonaxial or excessive prosthetic loading, poor denture support, poor balance,
or occlusal rocking. The case was complicated because another
dentist attempted to remove the fractured part with an unsuccessful outcome, decreasing the possibility of removing the
screw with special removal systems. Therefore, a cast metallic
dowel with ball attachment reproduction was constructed to use
the existing implant and overdenture, saving the patient’s time
and the cost of a new implant and a new overdenture.
Fracture of an abutment screw is a challenging complication of implant-supported restorations.19 Although a fractured
screw should be retrieved and replaced by a new one without
any damage to the internal threads of the implant, in some
cases, it cannot be removed.17 In the literature, various techniques have been described to decrease the risk of implant
damage.11-17 Retrieving the fractured screw is the best solution; however, an alternative method was used for this patient,
who required placement of a custom-made metallic dowel into
the implant. In situations in which the fractured screw cannot
be removed, and the inner surface of the implant is damaged,
the implant would be sacrificed, the treatment plan would be
changed, and new implants would be inserted with additional
cost. This conservative management is easy to perform, costeffective, and time-efficient and does not require additional
equipment. On the other hand, the aim of this technique should
be to avoid any further complications such as loosening of
the dowel. Retrieving the fractured parts is important, but so
is defining the reason for failure and eliminating those factors, including checking the occlusion, eliminating premature
contacts, and equilibrating the chewing force.15 It is highly recommended that a detailed clinical examination be performed to
identify parafunctional activities, such as bruxism, which may
cause component fractures.13
C 2014 by the American College of Prosthodontists
Journal of Prosthodontics 23 (2014) 402–405
Fractured Abutment Screw
Canpolat et al
Conclusion
This report suggests that a conventional technique used for
natural teeth such as cast dowel with ball attachment may be a
useful compromise option for replacing failed implant abutment
screws in such cases.
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C 2014 by the American College of Prosthodontists
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