Background: Peri-implant bone level values have been used as the clinical standard of reference to describe the status of a dental implant, despite the fact that their significance for the long-term survival of the implant has never been properly assessed.
Purpose: To challenge the assumption that the natural course of peri-implant bone loss is the loss of the implant.
Materials and methods: This article is a narrative review on reasons and interpretations of marginal bone level changes around dental implants.
Results and conclusions: Different views regarding the pattern and progression of marginal bone loss depending on dental specialties have been identified. However, the present finding of a negative correlation between an increasing cumulative marginal bone loss and a decreasing risk of implant failures over time indicates that peri-implant marginal bone loss does not necessarily represent a condition of disease. Reduction of marginal bone levels may be observed in a majority of patients during follow-up time, with only a minority of those patients losing implants and implant-supported prostheses in the long term. Bone level changes seem often to occur as a consequence of physiological processes and/or as an adaptation to altered external as well as host response factors. Periodical radiological assessments of implant-restorations remain a valid diagnostic tool for the detection of potential implant fractures, loss of osseointegration, screws working loose and for the detection of the few cases with advanced, continuously progressing marginal bone loss during time. The detection of peri-implant marginal bone loss at one time point should not be immediately considered as a sign of ongoing pathology and of an increased risk of future loss of the implant in question.
Keywords: bone loss; cumulative survival rate; implant failure; marginal bone level; oral implants.
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