Consistent Complication Discoveries between Level II and Level IV Fractured Abutment Screw Cases

It’s hard to imagine practicing modern restorative dentistry without the assistance of implant dentistry for additional support and stability of our restorations. Implants can allow for a more conservative restorative solution for helping patients avoid additional dental tooth or bone loss. Most of the restorative solutions incorporate the use of screw retained components, often at multiple levels of a construction.

While the vast majority of these screws function as intended, some do not, and for various reasons. When this occurs, we are often asked to recover screws that have lost their drive geometry, which then blocks retrieval of a prosthesis, or to recover a residual screw fragment, from either abutment or prosthetic screws. While many of these fragments are straight forward to recover, others are not. This review will first identify a treatment algorithm which has been very helpful in my practice to classify these cases, so the appropriate treatment protocols can be used. Then, it will lead into four case studies that have educational merit to understand the reasons these cases required a more comprehensive retrieval protocol, most of which can be credited to flawed, prior recovery decisions and efforts.

A Classification and Treatment Algorithm for basic recovery of fractured screw fragments

This classification is based on two rather straight forward observations based on a fractured, retained abutment screw, but can be applied to any fractured screw. First, a retained screw fragment can be classified as either mobile or non-mobile, when examined with an explorer, most often an endodontic explorer, which has the length to reach the top of the fragment residing internally in an implant. For the most accurate assessment, this evaluation is best conducted under magnification with adequate lighting. I routinely use a clinical microscope in the 16- 25x range. This is important, because a lessor examination may direct treatment in an inappropriate direction, as the assessment of mobility may be misdiagnosed. The second observation is to determine where the top of the screw fracture resides, relative to the first implant thread. If the fracture was through the screw threads, then specifically, is the lead thread of the fractured screw above the implant lead thread or below? This is significant, as it definitely affects the ease of retrieval of a screw fragment. Once these two observations are made, there are only four possible clinical situations, and each has its own treatment approach. These are listed below.

These case types are ordered and progressively become more difficult to recover as the case type gets larger.  Most definitely, the risk to the implant threads increases with the case type.  If haphazard recovery attempts are made, there are many situations where a Type I case becomes a Type III case, and when an implant thread is altered, then the Type III case becomes a Type IV case.  Generally, a mobile Type I or III case can be recovered without the need for rotary instruments, using only a microscope, endodontic explorer or modified endodontic spoon excavator, which can deliver somewhat more rotational torque and speed up the process due to the pointed curved tip.

In my practice, I tend to receive referrals after the initial recovery attempt failed, so the case may or may not be the same as before the initial attempt, depending on how the attempt was operated. After treating over 1300 of these cases, I have developed some general guidelines to avoid complicating a case and making the problem harder to resolve. The guidelines are listed below:

1. If you do not have access to a clinical microscope, you should not attempt these recoveries with any instruments other than hand instruments. Therefore, no rotary instruments are to be used internally in an implant. The hand instruments include the endodontic explorer, modified endodontic spoon excavator, and mouth mirror. These are the three hand instruments I use in my basic diagnostic setup, along with the clinical microscope. In cases where there have been no prior attempts in Type I and III cases, I routinely recover up to 70% of fractured abutment screws with this setup alone. Without the microscope, that percentage would drop dramatically because visualization is not good enough to accurately assess or direct the recovery effort.
2. Do not use ultrasonic instruments internally in an implant, attempting to vibrate a screw loose. I don’t believe the risk of implant damage is worth any gains that might be made over the protocol in point #1. Significant implant damage can quickly occur, and it does not take much to progress into a Type IV case or worse make the implant non-restorable. For a more in depth discussion of ultrasonic use please go to this link https://mastrovichdental.com/featured-case-study/ultrasonics-complications-of-abutment-screw-retrieval-secondary-to-prior-ultrasonic-attempts/

If the fragment is not mobile when tested, as described above (Type II and IV cases), then an approach to increase rotational torque on the fragment must be used.  Review of these four cases will describe the process used to save all four cases, starting with the most straight forward and progressing to a very compromised case, necessitating a more complicated restorative protocol to save the case.  The first three cases illustrate where an unsuccessful drilling protocol was used with two different generic recovery kits, with the net result of actually complicating  the case.  The fourth case illustrates how the use of an ultrasonic instrument dramatically complicated resolution of the case.

In the following four case studies, I will illustrate these issues. These cases offer valuable insights into Four Type II and IV Fractured Abutment Screw case studies with increasingly complicated recoveries. By understanding these risks, we can make better-informed treatment decisions and potentially avoid complications in future restorations.

Contact Dr. Mastrovich and the Mastrovich Dental Team for more information on our Implant Mechanical Rescue services.