The predictability and long-term success rate of dental implants are well documented in the literature. Nevertheless, complications and failures do occur and can have a significant impact on overall treatment. Peri-implantitis is one of the most common biological complications affecting functional implants. Even though the exact causes of peri-implant diseases is the bacterial biofilm, numerous factors may increase the risk of developing peri-implantitis. Risks may be reduced and even eliminated if some related factors are controlled. This lecture will discuss risk indicators to identify susceptible patients so that a customized treatment plan can be provided for each patient, depending on the relevant needs. Also, it will evaluate common problems encountered with the restorative phase providing an understanding of how and why problems exist and ways to reduce them.