Today, I would like to start with a historical picture. Take a close look at the person in the photo. Notice that she has a closed breathing circuit, so that not even the air she breathes will escape in the environment. You might think that the photo is from a deadly virus outbreak or a space movie. Today, it might be hard to believe that the person in the astronaut suit was actually a dental surgeon on her way to perform an implant surgery in the late 70s. After 40 years of research, implant dentistry has come a long way since that pioneering times. The indications for implant placements have expanded and more than 10 million dental implants are placed worldwide every year. Does this mean that implants are for every one with missing teeth? Certainly not! Despite the significant progress, not everyone is suited for dental implants and careful patient selection remains still the most important factor to ensure long term success. From a systemic point of view, we identify two types of contraindications for dental implants: the absolute and the relative. As you guessed, the absolute contraindications are few. The relative, however, are the tricky situations where the evidence is not conclusive and our clinical judgement needs to be well supported by the current best practices and guidelines. Let's take a look at the main contraindications for implant therapy as based on the currently available evidence. Highest in the list is: plaque and periodontal inflammation. Today, we know well that bacterial plaque is the No. 1 enemy for the long term survival of dental implants. If bacterial plaque is left to accumulate on dental implants, inflammation of the peri-implant tissues in the form of Peri-implant mucositis or peri-implantitis is the expected tissue response. Peri-implantitis is a condition that is difficult to manage. And as we will see in one of the next modules, it can pose a serious threat to the survival of dental implants. Consequently, if your patient is not able to practice effective oral hygiene, or if he has an active periodontal disease, do not proceed with dental implants. The next group is the modifying factors, factors which would not cause implant failure directly but they can modify our body's immune response, amplify the effects of inflammation, compromise the healing ability of the body, and increase the risk for failures either in short or long term. Diabetes mellitus is among the most well-studied modifying factors. Diabetes is a metabolic disorder which is defined by patient's inability to maintain a stable blood sugar level. In reality, however, diabetes can include a wide array of pathological conditions and such patients appear to be more susceptible to periodontal and peri-implant inflammations while they might also present with compromised wound healing. The metabolic control is the key for decision making in such patients. And this is expressed by the value of glycated hemoglobin (A1C), which should be less than 7% in order to consider the patient in “tight control”. A patient under “tight control” is a good candidate for implant placement, while a value bigger than 7% will indicate that improvement of the metabolic control is required before we proceed with implant placement. Similarly, a lot of research has documented the detrimental impact of smoking for the longevity of dental implants. Smokers get a higher risk of peri-implant inflammations, compromised healing ability, and lower success rates in the medium and long term. Again, the effect appears dose related. Heavy smoking increases the risk for both early failures, as well as, long term complications. Although it does not constitute an absolute contraindication, every patient should be offered smoking cessation support and advice to quit or reduce smoking before implant placement. If smoking persists, the patient must be made aware of the increased risks and strict maintenance must be exercised.
