During the interval between the sixth and seventh year of functional loading, a slightly higher rate of failures than that in the previous years was observed.

The ratio between the rate of peri‐implant complications and the time of function was even more evident for peri‐implantitis, which showed a significant increase after the seventh year of functional loading, with a more evident increase among implants. The results also showed that the rate of peri‐implantitis tended to remain stable after the seventh year of functional loading, and this stability was particularly evident among implants (Table 4). The increase in the rate of patients with peri‐implantitis between the sixth and seventh year was not as high as that among implants, which could be mainly attributed to the fact that patients who develop peri‐implantitis typically have >1 implant in place, and the probability of developing peri‐implantitis is higher in individuals with ≥4 implants.

In the last part of the observation period, after the eighth year of functional loading, a decrease was observed in the number of failures among patients and among implants. According to Lang et al, and Lang and Berglundh this decrease could be mainly attributable to the effects of the therapeutic measures adopted following the CIST (cumulative interceptive supportive therapy) protocol.

In regards to data on peri‐implantitis among patients (P) and among implants (I), the results observed in the present study were similar to the data gathered by Dvorak et al. (23.7% P and 13.3% I), Mir‐Mari et al. (16.3% P and 9.1% I), and Cecchinato et al. (23% P and 11.3% I).

However, at the fifth year, the peri‐implantitis data were similar to the 3.4% value observed in the same period of 5 years by Gatti et al. Similarly, Rodrigo et al. reported a prevalence of peri‐implantitis of 2.9% among implants after 5 years of follow‐up.