4.3 Periodontal Assessment, Probing Techniques & Furcation Classification

Periodontal Assessment, Probing Techniques & Furcation Classification

Quick Answer: Comprehensive periodontal assessment measures probing depths, Clinical Attachment Level (CAL), furcation involvement, tooth mobility, and mucogingival status. CAL represents true periodontal destruction and is calculated from the CEJ: CAL = Probing Depth + Recession (when margin is apical) or CAL = Probing Depth - Overgrowth (when margin is coronal). Furcation involvement is classified using Glickman Grades I through IV, tooth mobility via Miller Classes I through III, and attached gingiva width by subtracting probing depth from total keratinized gingiva width.

1. Periodontal Probing Technique and Mechanics

Periodontal probing is the single most essential clinical diagnostic procedure for evaluating gingival health, depth of periodontal pockets, and loss of clinical attachment. Accurate probing requires strict adherence to standardized ergonomics and probing mechanics.

Probe Instrumentation and Ergonomics:

• Probe Selection: Standardized calibrated probes feature millimeter markings. Common designs include the UNC-15 (color-coded at 5, 10, 15 mm), Marquis (3-6-9-12 mm bands), Williams (1-2-3-5-7-8-9-10 mm), and Michigan O. The Nabers curved probe is specifically designed with a curved working end to evaluate furcation entrances.
• Grasp and Fulcrum: A modified pen grasp with a light, solid intraoral finger rest (fulcrum) on an adjacent stable tooth surface.
• Probing Force: Recommended probing force is extremely light, ranging between 10 and 20 grams (equivalent to the pressure required to indent a ripe tomato without breaking the skin). Excessive probing pressure forces the probe tip past the junctional epithelium into inflamed connective tissue, generating false deep readings and causing tissue trauma.
• Walking Probe Technique: The probe tip is kept in continuous contact with the root surface inside the sulcus/pocket. It is moved in 1 mm up-and-down bobbing steps along the circumference of the tooth, recording the deepest measurement across 6 sites per tooth:
  1. Distofacial
  2. Facial
  3. Mesiofacial
  4. Mesiolingual
  5. Lingual
  6. Distolingual
• Interproximal Angulation: Beneath interproximal contact areas, the probe is angled slightly into the col area directly under the contact point while keeping the probe shank as parallel as possible to the long axis of the tooth.
• Bleeding on Probing (BOP): BOP signifies active micro-ulceration of the sulcular epithelium due to inflammatory responses to bacterial plaque. While BOP indicates active tissue inflammation, the absence of BOP is a highly reliable predictor of periodontal stability.

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2. Calculating Clinical Attachment Level (CAL)

Probing Depth (PD) alone does NOT measure total bone or tissue loss because PD is dependent on the position of the gingival margin. Clinical Attachment Level (CAL) measures the distance from a fixed anatomical landmark—the Cementoenamel Junction (CEJ)—to the base of the periodontal pocket.

Clinical Attachment Level (CAL) Scenarios:
1. Margin APICAL to CEJ (Recession):   CAL = Probing Depth + Recession
2. Margin CORONAL to CEJ (Overgrowth): CAL = Probing Depth - Overgrowth
3. Margin AT CEJ:                      CAL = Probing Depth

Formulas and Clinical Calculations:

Scenario 1: Gingival Margin is APICAL to the CEJ (Gingival Recession)

When recession exposes the CEJ, the distance from the CEJ to the margin is added to the probing depth. $ext{CAL} = ext{Probing Depth (PD)} + ext{Gingival Recession}$ NBDHE Sample Problem: A mandibular canine exhibits a Probing Depth of 4 mm, and the gingival margin is located 3 mm apical to the CEJ (3 mm of visible recession). What is the CAL? $ext{CAL} = 4 ext{ mm (PD)} + 3 ext{ mm (Recession)} = 7 ext{ mm of attachment loss.}$

Scenario 2: Gingival Margin is CORONAL to the CEJ (Gingival Overgrowth / Pseudo-pocket)

When inflamed, edematous, or hyperplastic tissue (e.g., drug-induced gingival overgrowth from phenytoin, nifedipine, or cyclosporine) covers the CEJ, the height of tissue above the CEJ is subtracted from the probing depth. $ext{CAL} = ext{Probing Depth (PD)} - ext{Gingival Margin Overgrowth}$ NBDHE Sample Problem: A maxillary molar presents with a deep Probing Depth of 6 mm, but the gingival margin sits 2 mm coronal to the CEJ due to tissue inflammation. What is the CAL? $ext{CAL} = 6 ext{ mm (PD)} - 2 ext{ mm (Overgrowth)} = 4 ext{ mm of attachment loss.}$

Scenario 3: Gingival Margin is AT the CEJ

$ext{CAL} = ext{Probing Depth (PD)}$

CRITICAL EXAM CONCEPT: Gingival recession INCREASES CAL, whereas pseudo-pockets mask true attachment loss if only probing depths are recorded!

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3. Glickman Furcation Classification System

Multi-rooted teeth (mandibular molars [2 roots], maxillary molars [3 roots], maxillary first premolars [2 roots]) are vulnerable to interradicular bone destruction. Furcation entrances are examined using a curved Nabers probe and categorized into four Glickman classes:

• Glickman Grade I (Class I): Incipient furcation involvement. The concavity of the furcation entrance can be felt with the Nabers probe tip, but interradicular bone loss is minimal. The probe cannot enter the furcation horizontally more than 1 mm. Radiographic changes are typically absent.
• Glickman Grade II (Class II): Moderate furcation involvement. The Nabers probe penetrates horizontally into the furcation concavity beyond 1 mm (partial penetration), but does NOT extend all the way through to the opposite side of the tooth. Interradicular bone is partially destroyed.
• Glickman Grade III (Class III): Severe, through-and-through furcation destruction. The Nabers probe passes completely through the furcation crotch from facial to lingual (in mandibular molars) or between mesial, distal, and facial roots (in maxillary molars). However, the furcation entrance remains covered by gingival tissue and is not visually visible.
• Glickman Grade IV (Class IV): Through-and-through furcation destruction identical to Grade III, but with severe gingival recession that clinically exposes the furcation entrance. The clinician can see completely through the exposed furcation crotch during visual inspection.

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4. Miller Tooth Mobility Classification System

Tooth mobility reflects periodontal ligament breakdown and alveolar bone loss. Mobility is tested by placing two rigid instrument handles (e.g., blunt ends of two mirror handles) on the facial and lingual surfaces of the tooth and applying alternating forces. Fingers should never be used because soft finger pads absorb force and yield inaccurate results.

• Miller Class I: Slight mobility; greater than normal physiological movement, but up to 1 mm of horizontal movement in a buccolingual direction.
• Miller Class II: Moderate mobility; horizontal movement greater than 1 mm in a buccolingual direction, but NO vertical (depressible) movement in the socket.
• Miller Class III: Severe mobility; horizontal movement greater than 1 mm combined with vertical depressibility (axial displacement) down into the socket.

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5. Mucogingival Assessment & Width of Attached Gingiva

The mucogingival junction (MGJ) demarcates the firmly bound, keratinized attached gingiva from the dark red, mobile, non-keratinized alveolar mucosa.

Calculating Attached Gingiva Width:

$ext{Width of Attached Gingiva (AG)} = ext{Total Width of Keratinized Gingiva (KG)} - ext{Probing Depth (PD)}$

1. Step 1: Measure the distance from the mucogingival junction (MGJ) to the outer edge of the free gingival margin = Total Keratinized Gingiva (KG).
2. Step 2: Measure the Probing Depth (PD) inside the sulcus/pocket.
3. Step 3: Subtract PD from KG.

NBDHE Sample Problem: A mandibular central incisor has a Total Keratinized Gingiva width of 4 mm and a Probing Depth of 3 mm. What is the width of Attached Gingiva? $ext{AG} = 4 ext{ mm (KG)} - 3 ext{ mm (PD)} = 1 ext{ mm of attached gingiva.}$