Reading a perio chart comparison
How the overlay view works and what counts as meaningful change.
Dentist· 3 min · Updated 14 Apr 2026
In plain language
A perio chart comparison overlays the current chart with one or two previous charts and highlights sites where the depth changed beyond a threshold — usually 2 mm.
Why it matters
Trend matters more than any single visit. A single 4 mm pocket is unremarkable; a 4 mm pocket that was 2 mm a year ago is a finding.
Faurenis's approach
Faurenis's comparison view uses two thresholds — a "worsened" red dot at +2 mm and an "improved" green dot at -2 mm. The legend explains both.
Risks & safeguards
- Probe operator variation — Faurenis notes that comparisons are most useful when the same hygienist is probing across the compared visits.