Removing fractured abutment screws
in implants with nonstandard connections
by Dr. Charles Schlesinger
Few things in implant dentistry strike fear in a
practitioner like a fractured abutment screw. There’s
a lot at stake for both the clinician and the patient. If
the clinician is unable to remove the screw, or the process
of removing the screw damages the implant’s internal
threads, the only option may be to remove the implant.
This, as you can imagine, is disappointing to all involved.
With the increasing use of dental implants in the
past few decades, the number of complications resulting
from such usage has also increased. Dental practitioners
must learn to recognize these complications and be ready
to manage them in their practice.1 In 2004, Jung et al.
reported that prosthetic screw fracture has an incidence rate
of 3.9% and the rate for prosthetic screw loosening is 6.7%.2
Since then, with the movement towards more stable conical
connections, fracturing is occurring in less than 0.5% of
cases.3
Implant abutment screws are very small, ranging in
diameter from 1.2 to 2 millimeters. These screws are
susceptible to fracturing by either being overtorqued at the
time of placement or bending when they become loose. As
an abutment screw comes loose, the abutment it secures
also will start to become loose. The abutment screw will
receive tensile and bending movements that can induce a
fatigue fracture.4
Case study
A patient was referred to my office for
removal of four abutment screws that had
fractured off inside the implants that were
retaining his maxillary overdenture (Figs. 1
and 2). According to the patient, these
implants and two others in the posterior
had Locator attachments that retained his
full upper denture. During the COVID-19
shutdown, he felt that his abutments were
loose and his denture was not “snapping” into
place like it used to. Being afraid to contact
his dentist and go to the office, he chose to
wait it out. Unfortunately, the abutments
became more loose, and eventually the screws
fractured off inside the implants (Fig. 3).
This type of fracture can occur if a
retentive abutment comes loose and is
not immediately torqued back down to
specification. In some cases, the screws—or,
in this case, the Locator abutments—will
have to be completely swapped out for
new ones. In this patient’s case, the reason
the abutments came loose was unknown,
and there was no way to ascertain what
happened because someone else delivered
the restoration. It was time to try to remove
the screws and help out the fellow dentist
and the patient.
Fortunately, abutment screws that
fracture like this are in the screw channel
passively—there is no tension or compression
on them, because the head of the screw (or
attached abutment) is missing. This allows
the screw to be removed if you can unscrew
it somehow.
Over the years, I have tried many ways
to remove screws, and some of them work
well. Trying to use a probe or explorer to
rotate the screw by hand can work, but can be tedious. Other methods include using
an ultrasonic tip to vibrate the screw out;
cutting a groove into the top of the screw
to use a small bladed driver to turn it; and
using a “claw”-type tool to slowly rotate the
screw (Fig. 4). The key to screw removal is
getting it out without damaging the implant’s
very fine internal threads. If these threads
are damaged, a new abutment screw will
not be able to be threaded into the implant.
A few kits and instruments on the market
these days—some generic, others sold by
specific implant manufacturers—can help
facilitate broken-screw removal. Most kits
consist of a reverse cutting pilot drill, which
is paired with a connection-specific guide
(Fig. 5). The guide fits like an abutment
into the internal connection of the implant
and guides the pilot to drill into the center
of the screw without wandering into the
side of the implant and damaging it. This
is extremely important in the cases where
the screw has fractured off deep into the
implant and there are threads coronally to
the segment of screw.
Along with the pilot and the guides
is a reverse-threaded tap or “easy out.”
This instrument, when run in reverse, will
thread into the preparation made in the top
of the fractured screw segment. Because
the instrument is reverse-threaded, as it
turns, it will grab the screw and turn it
counterclockwise, eventually unscrewing
it completely from the implant.
In this case, the ERI implants from OCO
Biomedical have a proprietary connection
that is not shared by any other implant on
the market; for this reason, a drill guide
was not commercially available to fit this
style of implant.
The referring office was contacted by
phone to identify the implant diameters. I
then took corresponding OCO Biomedical
impression copings for the specific sizes.
After removing the placement screw, a
handpiece was used to slightly modify the
screw channel to increase the diameter:
A long-shanked surgical 557 carbide was
used to remove the internal lip inside the
coping so the pilot bur would be able to
move smoothly through it. Then the two
flat sides were adjusted to allow a handle to
slide on for stability when drilling (Fig. 6).
Once this was fabricated, I now had a stable guide for the pilot to work through.
Before starting, the implants were thoroughly
irrigated with sodium hypochlorite
and flushed with copious amounts of water
to remove any debris that could inhibit the
procedure. The guide was placed on the first
implant and held firmly with the handle
(Fig. 7). An Aseptico implant motor
was set to 1,400 rpm in reverse mode with
30% irrigation. The pilot (Nobel Biocare,
Fig. 8) was run through the guide
until approximately a 0.5–1 mm divot was
created in the top of the fractured segment
(Fig. 9), and the guide made sure the
divot was made in the center of the screw
segment (Fig. 10).
Once this was completed, a handpiece
with a tap (Nobel Biocare) was set to
20 rpm in reverse without irrigation. The
tip of the instrument (Fig. 11) was placed in
the divot and the rheostat was pushed. The
counterrotation of the instrument and the
left-handed threads of the tap caused the
instrument to “bite” into the metal of the
screw and rotate it in a counterclockwise
direction. Eventually, the broken segment
reached the top of the screw channel and
stuck to the instrument (Fig. 12); in other
cases, the segment can be removed with
small cotton pliers or suction.
This process was repeated for the next
three implants. It was necessary on a few of
them to drill, try to tap and then redrill in
order to remove all the segments (Fig. 13).
Once all the fractured screws were
removed, the threads were cleaned with
an appropriately sized broach from Regal
Cutting Tools (Fig. 14) and flushed to assure
that new Locator attachments would thread
down without issue. A final film was taken
to make sure the screw channels were clean
and clear (Fig. 15). The patient was released
back to the referring dentist for completion
of treatment and further evaluation on the
reasons for the prosthetic failure and crestal
bone loss.
Conclusion
Although this technique is definitely DIY,
it is one of those instances where the stakes
are high if the screw cannot be removed or the
internal threads of the implant are damaged.
Despite all the precautions undertaken, if
there is any damage to the internal anatomy
of the implant, a post-and-corelike prosthesis
for the implant can be considered as a last
resort to restore function.5
This type of workaround to the conventional
screw-retrieval systems with implant-specific platforms can be accomplished
with any system that has a unique
or known platform. With care, one can
make modifications to a stock abutment
or impression coping to guide a specialized
pilot drill for the purpose of facilitating
screw removal.
The modern dental practice sometimes
throws us a curveball, and ingenuity becomes
the mother of invention. Thinking outside
the box to solve a problem will allow any
of us to do the best we can for the patients
that rely upon us for their oral health.
References
1. Leung, B. “A Review of Implant Screw Fractures: Their
Causes and Methods of Retrieval.” Oral Health Group
Weekly. Nov. 15, 2017.
2. Palakru, S., Guntakala, V., et al. “Noninvasive Method
for Retrieval of Broken Dental Implant Abutment Screw.”
Contemp Clin Dent. 2014 Apr-Jun; 5(2):264–267.
3. Salinas, T., Eckert, S. “Implant-Supported Single
Crowns Predictably Survive to Five Years with Limited
Complications.” J Evid-Based Dent Pract. 2010; 10:56–57.
4. Flanagan, D. “Management of a Fractured Implant
Abutment Screw.” J Oral Implantol 2016; 42(6):508–511.
5. Joshi, A., Kale, V.T., Suragimath, G., Zope, S.A. “An
Unconventional Approach for Retrieval of Fractured
Prosthetic Screw: A Case Report.” J Osseointegr 2018;
10(3):75–78.
Dr. Charles Schlesinger, a
fellow of the International
Congress of Oral
Implantologists, is a dental
implant practitioner and
educator who has lectured
internationally for 16 years.
After graduating with honors
from The Ohio State College
of Dentistry in 1996, he
completed a general practice residency at the Veterans
Administration Medical Center in San Diego and went on
to become the chief resident at the VAMC in West Los
Angeles. While in Los Angeles, he completed extensive
training in oral surgery, implantology and advanced
restorative treatment.
After 14 years practicing in San Diego, Schlesinger
moved to Albuquerque to become the director of
education and clinical affairs for a medical device
manufacturer, and eventually also became its chief
operating officer. He returned to private practice
in 2016, and two years later became the COO of
Comfortable Dentistry 4U, a multipractice group. He
also continues to provide patient care in Albuquerque.