Dr. Beatrice Leung Dentistry Professional Corporation

Dental Professional? Click Here

Minimizing Implant Prosthetic Complications-Other Considerations

Since I started writing these posts, I saw in increase in referral from my colleagues with implant related complications.  Many of their patients have received treatment outside North America with different implant systems and treatment philosophies.  As I am seeing more of these complications, all the more reasons I want to share with these problems with my colleagues in the hope to help everyone tackle them more systemically and efficiently.

A common scenario is that my reception staff gets a call: there is a patient who has a broken implant screw or broken implant bridge.  There is no information on the type of implant system or the details of the prosthetic problem.  If I am lucky, I may be able to get some radiographs to have an idea what the problem is.   Often times, I have to do some investigative work to arrive with a diagnosis so I can provide a solution to the patient in a timely manner.  Added to this, living in Toronto with a multicultural environment, some of these patients do not speak English and with the added language barrier, it can be a challenge to obtain the history of the clinical problem.

Luckily, I have worked with different major implant systems so my office is equipped with a variety of tools for different systems.  However, I propose that it should be a standard of care that patients should be given a record of their implant treatment to facilitate any future repair needs.  There are some online tools available to help dentists determine what implant system their patients have.  I haven’t had the need to use them yet but thought I should share this with you all.  http://whatimplantisthat.com  And because I know implant complications will happen irrespective of the type of implants use, I tend to stay away from some of the smaller implant companies or ones that are new to the industry for my implant prosthetic cases.  I never know if these implant companies will be around in a few years and often find their prosthetic options to be quite limited.

Going back to my initial topic, I wanted to talk about manufacturing issues as they relate to broken screws.  Whenever possible, I would recommend using authentic components from the appropriate implant companies.  They are designed to work with their specific implant systems.  I had an experience where the dental laboratory likes to use a customized CAD/CAM abutment from another company.  While I have had no issue with the design, there was one incident where the screw provided by the company didn’t fit into the screw access channel.  For this particular lab, they like to send the screw in an unopened package.  Their rationale for this practice is to show their dentists that they don’t re-use their screws.  I personally don’t like this practice because if there are issues with the screws, it would be me to find this out and this often means time lost as I have to send the case back to the laboratory to get it fixed.  I personally would want to receive the prosthesis on the model with the final screw attached.  This way, I know that if there are manufacturing issues relating to these components, they would have been discovered and fixed prior to sending it to my way.

Once I have received the laboratory case, even if the prosthesis and screws are packaged separately from the model, I make a habit of placing them on the model first.  This gives me the opportunity to test run how all the components fit together. I would specifically evaluate how the path of the screw and the prosthesis must travel before being seated and the angle of the driver must be in prior to tightening the screw.  I’d like to figure all these out before transferring any components to the mouth.  As many of you can imagine, once the components are transferred to the mouth, there is the added challenge of access from limited mouth opening or the presence of the movable tongue interfering with your work.  Having a prior run through of how all the components fall into place in the model helps me make the try in and insertion process much more smooth sailing.  This will minimize the risk of stripping the screws or damaging the components during the try in phase of the treatment.







Shown above are pictures of a case utilizing multi-unit abutment and its corresponding gold cylinder from Nobel Biocare to provide a screw retained restoration at implant site 46.  These pictures were quite dated so today I would have used a different prosthetic solution in this clinical situation.  At the time, this was a solution to providing a screw retained restoration even though the angulation of the implant is less than ideal.  The use of multi-unit abutment and a gold cylinder is also popular in the All on Four treatment option for fully edentulous cases.  I took several pictures  here to illustrate how the driver for seating the mult-unit abutment is more lingual than that for the gold cylinder.  I usually like to play with these components on the model before trying to transfer them in the mouth.  It can be quite challenging in posterior areas for people with large tongue and limited mouth opening.  Also, the torque value for the screw for the multiunit abutment is DIFFERENT from the screw for the gold cylinder which subsequently becomes the prosthetic screw for the restoration.  Please beware so you don’t overtorque the prosthetic screw leading to stripping or breaking the screw.

I’m showing these pictures of a case for an implant bridge with lab screws coming through the screw access channels.  The extra long lab screws help to illustrate the direction/projection that you must follow to position the prosthetic screws in tightening

To me, these little things matter and I hope you will find the information here useful too.  If you have any great ideas to share, I look forward to hearing from you at drleung@drbeatriceleung.ca.