Bleeding on probing around dental implants: a retrospective study of associated factors.

AIM: To (i) identify factors associated with the probability of a peri-implant site to be positive to bleeding on probing (BoP+) and (ii) compare BoP+ probability around dental implants and contra-lateral teeth. METHODS: In 112 patients, data related to 1725 peri-implant sites and 1020 contra-lateral dental sites were retrospectively obtained. To analyse the association between patient-, implant- and site-related factors and BoP+ probability, a logistic, three-level model was built with BoP as the binary outcome variable (+/-). RESULTS: BoP+ probability for a peri-implant site with probing depth (PD) of 4 mm was 27%, and the odds ratio increased by 1.6 for each 1-mm increment in PD (p < 0.001). Also, BoP+ probability was higher in females compared to males (OR = 1.61; p = 0.048), and lower at posterior compared to anterior dental implants (OR = 0.55; p < 0.01). No significant difference in BoP+ probability was observed between peri-implant and contra-lateral dental sites when controlling for the difference in PD. CONCLUSIONS: The probability of a peri-implant site to bleed upon probing is (i) associated with PD, implant position and gender, and (ii) similar to that observed at contra-lateral dental sites when controlling for the effect of PD.