Implant infection can occur soon after implant placement or many years later. Infection occurring soon after implant placement tends to progress more rapidly than infection that occurs after the bone has grown into the implant ("osseointegration"). Any type of implant infection needs treatment, but prevention is best.
Infection that occurs after osseointegration has been divided into two stages: the first stage is when bacteria have colonized the tooth or implant surfaces causing a reversible inflammation of the gums and connective tissue without any bone destruction. This is known as "peri-implant mucositis" and is equivalent to gingivitis around natural teeth. The second stage represents the progression of peri-implant mucositis to the point that bone destruction has occurred. This is known as "peri-implantitis" and is equivalent to periodontitis around natural teeth. Collectively, these two stages of the disease are known as peri-implant infection.
Peri-implant infection is common with peri-implant mucositis occuring in up to 64% of implants. This can, but does not always, lead to the bone destruction that defines peri-implantitis, which occurs in approximately 10-15% of implants. Peri-implantitis has been found to be clustered in approximately 20% of implant patients, with smoking and a history of periodontitis as major risk factors. Approximately 10% of all implants are lost over a 10 year period due to peri-implantitis.
The process begins when bacteria colonize the crown or implant surface within minutes of implant placement. If the right combination of virulent bacterial species is left to grow without adequate daily hygiene and periodic professional maintenance, then inflammation can occur after several weeks of bacterial accumulation, resulting in peri-implant mucositis. This inflammation, if left untreated, can lead to destruction of the bone seen in peri-implantitis. The implant can fail and be lost if enough bone is destroyed. Fortunately, the infection usually progresses very slowly and painlessly so that if an implant is lost, many years of use have been enjoyed by the patient. Unfortunately, the bacteria that cause this infection have been strongly associated with other systemic diseases such as heart disease, stroke, cancer, diabetes, etc. Important points to remember are: 1) peri-implant infection is usually painless so you will not know that it has occurred, and 2) while it can be treated and controlled, there is no cure, and it won't resolve on its own, therefore constant follow-up and maintenance is needed.
The only known means to diagnose peri-implant infection is periodontal probing by a dental professional. X-rays and a visual examination can add useful information, but the infection cannot be diagnosed without probing, as your dentist cannot see the inflammation below the gum line on an x-ray or with their eyes alone. If there is infection around an implant, then bleeding or pus will be seen on probing. Deep pockets do not necessarily indicate any bone loss, but does indicate inaccessible areas that are difficult or impossible for you to clean.
The bacteria constantly try to colonize all the surfaces in your mouth, especially your teeth, so they need to be removed with brush and floss on a daily basis. There are likely areas that are inaccessible for you to clean, so professional cleaning is required. The frequency of these cleanings is best determined by a dentist experienced in treating implant infection.
Oftentimes, even the dentist and hygienist cannot clean the implant crowns effectively while they are in place. For this reason, it is best if implant crowns are made with an access hole so that the dentist can periodically remove the retaining screw that holds the crown onto the implant. This does not remove the implant, but allows removal of the crown which is where the infection starts. With the crown off, it can be fully disinfected as often as needed and the implant itself can be accessed easily for cleaning and assessment, which is rarely possible with the crown in place. This process, known as "implant maintenance" (CDT Code D6080) often needs to be performed every 3 months. The rationale behind this is that even if there is bone destroying inflammation at the crown/implant interface, the inflammation will not have the ability to destroy any implant supporting bone if the bacteria are being cleaned out every 3 months.
Its important to understand that the screw access hole in the crown can be made very small and plugged with tooth colored material, although some crowns, especially on your front teeth, often cannot be made with the screw access hole on the back side of the tooth. As its unacceptable to place the access hole on the front surface of a front tooth, these crowns are rarely made with a screw access hole. They can be cemented in with a special cement that allows removal of the crown to gain access to the retaining screw, but this has not been perfected.
In our office, we always assess the level of inflammation upon crown removal during implant maintenance. If we see minimal signs of inflammation, then we recommend decreasing the implant maintenance frequency to a 4 month interval. If inflammation does not occur at the following implant maintenance appointment, then the frequency is decreased to every 6 months. The minimum recommended frequency for implant maintenance is once per year unless the pocket around the implant is easily accessible and fully probe-able, which is not common due to the bulbous shape of most implant crowns. After implant maintenance in our office, we fill the access hole with teflon tape and temporary onlay composite called "Fermit". This makes it very easy to remove and replace the crowns on subsequent appointments.
Implant Direct branded implants are very amenable to crown removal as their retaining screws are inexpensive and are made of titanium which is very durable, therefore these screws can be loosened and retightened many times before replacement of the screw is required. 3i Implants use a special screw that costs considerably more than the Implant Direct screw, and 3i recommends replacement with a new screw after each removal.
With diligent daily brushing and flossing, and frequent maintenance, peri-implant infection can be avoided resulting in implants that may very well last a lifetime and good health overall.