Leftover pockets after perio therapy don't stay quiet at implants

Treated periodontitis patients make up a large share of implant candidates, but whether residual probing pocket depth (PPD) left over after active periodontal therapy actually raises peri-implant risk has never been reviewed systematically. This PROSPERO-registered systematic review (CRD42024567630) searched MEDLINE, Scopus, Embase and Cochrane Library and screened 3,870 records, narrowing to 4 cohort studies with follow-up ranging from 1 to 23 years — all evaluating residual PPD as the exposure of interest; none specifically assessed furcation involvement.

Despite heterogeneous exposure and outcome definitions across the four studies, the direction of effect was consistent: residual PPD persisting after active periodontal therapy was associated with a higher incidence of peri-implantitis. Deeper residual pockets (≥5 or ≥6 mm) and a higher proportion of residual diseased sites carried greater risk, and one study found that ongoing periodontal inflammation at adjacent natural teeth also raised peri-implantitis risk around the implant. Substantial methodological heterogeneity meant meta-analysis was not feasible, and most studies carried a moderate risk of bias (Newcastle-Ottawa Scale).

The clinical read is straightforward even without pooled effect sizes: periodontal therapy that leaves deep residual pockets is not a closed chapter before implant placement — it is a carried-over risk factor. The authors call for prospective studies with standardized peri-implantitis case definitions to quantify that risk more precisely, but the consistent direction across four independent cohorts already supports treating residual PPD as a modifiable checkpoint before moving a periodontally treated patient to implant therapy.