The Screw Head of the Dental Implant Broke Off. Is This Common? How Difficult to Fix?

It is not common to have screw heads in dental implants break, but they DO happen.  Modern materials and techniques are designed to avoid this happening, but "never say never".

It is important to know WHY it broke.  It is possible that a different size implant should be used, a different technique or a different brand.

I am not exactly certain what you mean by the "screw head". There is the healing abutment (placed after surgery while implant heals) and the prosthetic abutment (which is placed on the implant to support the new crown). If it is the prosthetic abutment that broke off and part of the screw is wedged or stuck in the implant body itself, it may be difficult or easy to remove depending on the skill of the dentist. Ask your dentist or seek out a PROSTHODONTIST (specialist in crown and bridge and implants) in your area to assist you to correct this problem. DO NOT LET YOUR DENTIST NOTCH ANYTHING. This may be irreversible and and destroy your implant forever. 

This is an extremely uncommon event in the hands of an experienced surgeon. This particular event is almost always due to one of two reasons. The first is lack of experience in placing dental implants. The reason the implant broke was because of too much torque placed on that particular implant. Whether it is from faulty implant (which is extremely rare if a legitimate implant brand was used, not a cut rate cheap implant company that the dentist used to save a few dollars) or a inexperienced dentist, too much torque was placed.  Removal is the only remedy. This usually needs to be done with a trephine bur. Using a laser against any metal object is tantamount to malpractice and is extremely dangerous.  I am curious as to what type of doctor placed this implant. The success rate would be excellent if removed  and replaced by a properly trained surgeon. Seek the help of a board certified Oral and Maxillofacial surgeon for help in this matter.  Beware of doctors that have only had a weekend course or two in dental implants. It takes several years of proper training to place implants safely,

Although not considered common I have seen broken implant screws occur from time to time. The interface between implant and abutment (or Implant Post) is retained by a screw that is torqued down to a certain amount of force that is recommended by the implant manufacturer. Assuming that there are no defective parts the specifics of the case must be considered to find out WHY this happened. Did the abutment or Post seat and fit accurately onto the platform of the Dental Implant? If not this could be the reason for Screw head fracture. Was the Implant Crown in a proper bite relationship with the opposing tooth? Additionally, was the right diameter Implant Platform selected? The retrieval of broken Implant Screws can be tricky and challenging. Usually there are specific retrieval kits made by the specific Implant manufacturer. I do not recommend  using a Dental Laser around Implants due to the amount of heat they generate. The retrieval of broken Implant parts takes patience and finesse but can be done in the right hands.

Unfortunately, it sounds like the tiny screw connecting the abutment (post) to the actual implant broke.  This is one of the rare complications we sometimes face in implant dentistry.  Retrieving the remaining screw is tricky.  I imagine your dentist will use a laser to remove any excess tissue and stop the bleeding in the area to get better visibility.  Then he will try to use a micro screwdriver to try and tease the screw out of the implant.   Sometimes it’s very difficult to accomplish this task, hopefully he’ll be successful.  Best wishes to your husband.