It is estimated that advanced periodontitis typically affects about 10% of most adult populations studied. These individuals can be considered highly susceptible to periodontitis and often present difficulties for clinicians in therapeutic decision making, especially when dental implants are involved. Poor plaque control and smoking are well established risk factors for periodontitis, as well as for peri-implant disease. Long-term follow-up studies have clearly demonstrated that treatment of periodontal disease, even if advanced, can be successful in arresting disease progression and preventing (or at least significantly delaying) tooth loss. With the increasing development of implant dentistry, traditional well documented and evidence-based therapies to treat periodontal diseases may sometimes not be used to their full potential. Instead, there appears to be an increasing tendency to extract periodontally compromised teeth and replace them with implants, as if implants can solve the problem. However, peri-implant diseases are prevalent, affecting between 28% and 56% of people with implants, and (at the implant level) 12-43% of implants. A history of periodontal disease, smoking and poor oral hygiene are all risk factors for developing peri-implantitis. Unlike periodontitis, there are currently no predictable means for treating peri-implantitis, although resective surgery seems to be the most effective technique. Consequently, if implant treatment is considered in patients who are susceptible to periodontitis, it should be preceded by appropriate and adequate periodontal treatment or re-treatment to control the condition, and should be followed by a stringent supportive maintenance program to prevent the development of peri-implant disease. The decision whether implant treatment should be performed should be based on an assessment of the patient's risk profile at the subject level, as well as at the site level.