Purpose: Peri-implantitis, a clinical term describing the inflammatory process that affectsthe soft and hard tissues around an osseointegrated implant, may lead to peri-implantpocket formation and loss of supporting bone. However, this imprecise definition has resultedin a wide variation of the reported prevalence; ≥10% of implants and 20% of patientsover a 5- to 10-year period after implantation has been reported. The individual reportingof bone loss, bleeding on probing, pocket probing depth and inconsistent recordingof results has led to this variation in the prevalence. Thus, a specific definition of peri-implantitisis needed. This paper describes the vast variation existing in the definition of periimplantitisand suggests a logical way to record the degree and prevalence of the condition. The evaluation of bone loss must be made within the concept of natural physiologicalbony remodelling according to the initial peri-implant hard and soft tissue damage and actualdefinitive load of the implant. Therefore, the reason for bone loss must be determinedas either a result of the individual osseous remodelling process or a response to infection. Methods: The most current Papers and Consensus of Opinion describing peri-implantitisare presented to illustrate the dilemma that periodontologists and implant surgeons arefaced with when diagnosing the degree of the disease process and the necessary treatmentregime that will be required. Results: The treatment of peri-implantitis should be determined by its severity. A case ofadvanced peri-implantitis is at risk of extreme implant exposure that results in a loss ofsoft tissue morphology and keratinized gingival tissue. Conclusions: Loss of bone at the implant surface may lead to loss of bone at any adjacentnatural teeth or implants. Thus, if early detection of peri-implantitis has not occurred andthe disease process progresses to advanced peri-implantitis, the compromised hard andsoft tissues will require extensive, skill-sensitive regenerative procedures, including implantotomy,established periodontal regenerative techniques and alternative osteotomy sites.