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A New Twist by Dr. Charles Schlesinger

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Categories: Implant Dentistry;
A New Twist 

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).
Dental Implant Abutment Screws_A New Twist
Fig. 1
Dental Implant Abutment Screws_A New Twist
Fig. 2
Dental Implant Abutment Screws_A New Twist
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.
Dental Implant Abutment Screws_A New Twist
Fig. 4
Dental Implant Abutment Screws_A New Twist
Fig. 5
Dental Implant Abutment Screws_A New Twist
Fig. 6 
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.
Dental Implant Abutment Screws_A New Twist
Fig. 7
Dental Implant Abutment Screws_A New Twist
Fig. 8
Dental Implant Abutment Screws_A New Twist
Fig. 9
Dental Implant Abutment Screws_A New Twist
Fig. 10
Dental Implant Abutment Screws_A New Twist
Fig. 11
Dental Implant Abutment Screws_A New Twist
Fig. 12


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.

Dental Implant Abutment Screws_A New Twist
Fig. 13
Dental Implant Abutment Screws_A New Twist
Fig. 14
Dental Implant Abutment Screws_A New Twist
Fig. 15


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.

Author Bio
Charles Schlesinger 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.

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