# Furcation Involvement > Furcation involvement for BDS Periodontics — Glickman and Hamp grading, Nabers probing, anatomy per tooth, and treatment options by grade. - Canonical URL: https://prepelephant.com/topics/bds/periodontics/furcation-involvement-bds - Exam / course: BDS · Subject: Periodontics - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Furcation Involvement", PrepElephant, https://prepelephant.com/topics/bds/periodontics/furcation-involvement-bds ## Direct answer Furcation involvement means periodontal destruction has reached the area between the roots of a multirooted tooth, changing both prognosis and treatment. Detection belongs to the curved, blunt Nabers probe walked into each entrance — buccal and lingual for mandibular molars, buccal directly and mesial or distal from the palate for maxillary molars — supported by altered radiographic angles or CBCT, since films hide most entrances. Grading follows Glickman's degrees I to IV — incipient cul-de-sac, deeper cul-de-sac, through-and-through hidden by gingiva, through-and-through visible from recession — while Hamp's horizontal classes quantify millimetres: under 3 mm, 3 mm or more but not through, and through-and-through. Treatment escalates by grade, from debridement alone for grade I, through odontoplasty and regeneration for grade II, to tunnel preparation, root resection or hemisection for grades III and IV. ## What you must remember - **Glickman grades:** I — incipient, soft tissue intact over the entrance; II — cul-de-sac entry without through-passage; III — through-and-through but gingiva hides the opening; IV — through-and-through with the opening visible from recession. - **Hamp classification (horizontal):** class I under 3 mm; class II 3 mm or more but not through-and-through; class III through-and-through — the millimetric version asked alongside Glickman. - **Vertical subclasses:** Tarnow and Fletcher graded vertical bone loss in the furcation as A under 3 mm, B 3-6 mm, and C over 6 mm — the qualifier that separates a savable furcation from a hopeless one. - **Probe:** the Nabers probe — blunt, curved, colour-coded designs — made specifically for furcations; a straight periodontal probe cannot negotiate the entrance. - **Anatomy by tooth:** in mandibular molars the buccal entrance lies nearer the cementoenamel junction than the lingual; in maxillary molars the mesial furcation is probed from the palate, the buccal directly, and the distal is hardest. - **Entrances are narrow:** about three-quarters are narrower than 1 mm — thinner than standard curette tips, so fine ultrasonic tips and dedicated furcation instruments do the debridement. - **Local anatomical risk factors:** cervical enamel projections into the furcation (Masters and Hoskins grades), enamel pearls, root proximity and cemental ridges that trap plaque. - **Treatment ladder:** grade I — scaling, root planing, sometimes odontoplasty; grade II — debridement with or without grafting or guided tissue regeneration; grades III and IV — tunnel preparation, root resection or amputation (maxillary molars), hemisection (mandibular), or extraction. ## Grading and treating a furcation A 52-year-old with treated periodontitis has a 6 mm pocket buccal to a mandibular first molar and radiographic fuzziness at its bifurcation. Probe the furcation deliberately: take the Nabers into the buccal entrance and walk it mesiodistally — it sinks 4 mm, meets sloping bone, but cannot pass through to the lingual side, which reads 2 mm. Glickman grade II; Hamp horizontal class II; the vertical loss judged from the film is around 3 mm, Fletcher subclass B. The plan follows the grade: meticulous debridement with fine curved ultrasonic tips plus furcation curettes, interdental-brush coaching, and re-evaluation at three months. If a clean vertical-walled component persists in a well-motivated patient, grafting or a membrane converts a plaque ravine into maintainable architecture. For contrast, the same molar with a through-and-through defect in a smoker is a different tooth: candid talk about tunnel maintenance, hemisection with root canal treatment of the retained half, or extraction — each priced against hygiene, caries risk and what the patient can sustain. ## Grade before you plan The fatal error is skipping the grade and choosing a procedure by habit. A candidate who proposes root resection for a grade II furcation has sacrificed a root to a defect that debridement and regeneration could have managed; one who proposes grafting a grade IV tunnel has scheduled a failure. Two memory tables carry the marks: Glickman's I-IV with its visible-versus-hidden distinction, and Hamp's millimetre classes with the 3 mm threshold — and the strongest answers append Tarnow and Fletcher's vertical A, B, C — vertical loss, not horizontal width, decides between resection and extraction. Anatomy questions follow: why the maxillary mesial furcation is probed from the palate (root eminences block the direct path), and why mandibular buccal entrances lie coronal to lingual. Finally, a treated furcation demands interdental-brush access forever — non-committed patients shift every option toward extraction. ## Frequently asked questions ### How does Glickman classify furcation involvement? Grade I incipient cul-de-sac; grade II deeper cul-de-sac without passage; grade III through-and-through hidden by gingiva; grade IV through-and-through with a visible opening. ### What are Hamp's horizontal furcation classes? Class I under 3 mm of horizontal probe entry, class II 3 mm or more but not through-and-through, and class III complete through-and-through passage of the probe. ### Which probe detects furcations and how? The curved, blunt Nabers probe, walked gently into each entrance — buccal and lingual in mandibular molars; buccal, and mesial or distal from the palate, in maxillary molars. ### What is root resection and when is it chosen? Surgical removal of one root of a maxillary molar after endodontic treatment of the retained roots, chosen for destruction confined to one root in a restorable, motivated patient. ### Why do furcations resist ordinary instrumentation? Most entrances are narrower than 1 mm — smaller than curette tips — and concave interradicular anatomy plus cemental ridges shelters calculus from instruments made for convex surfaces.