Periodontal Probing & Charting

Periodontal Probing & Charting

Probing Depth Measurement and Technique

Periodontal probing is the primary method for evaluating the health of the periodontium. The probing depth (PD) is defined as the distance from the free gingival margin to the base of the sulcus or periodontal pocket.

Clinical Protocol:

1. Measurement Sites: The clinician records six pocket depth measurements per tooth:
   • Facial/Labial Aspect: Distofacial (DF), Facial (F), and Mesiofacial (MF).
   • Lingual/Palatal Aspect: Distolingual (DL), Lingual (L), and Mesiolingual (ML).
2. Instrumentation: Standardized, calibrated probes are utilized, such as the Marquis probe (3-6-9-12 mm markings), the UNC-15 probe (millimeter markings from 1 to 15), or the Williams probe (1-2-3-5-7-8-9-10 mm markings).
3. Technique: The probe tip is inserted gently into the sulcus, maintaining contact with the tooth surface. The probe must be kept parallel to the long axis of the root. A 'walking stroke' is employed-moving the probe in 1 mm increments along the pocket floor-to detect the deepest point of the site.
4. Col Angling: At the proximal surfaces, the probe must be angled slightly (approximately 10-15 degrees) beneath the contact area to assess the col (the non-keratinized depression connecting the facial and lingual papillae), where periodontal disease typically initiates.
5. Probing Force: A standardized force of 10 to 20 grams of pressure is applied. Excessive force can penetrate the junctional epithelium, leading to false-positive deep readings.

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Clinical Attachment Level (CAL) Calculations

While probing depth measures the distance from the moving gingival margin to the pocket base, the Clinical Attachment Level (CAL) measures the distance from a stable, permanent anatomical landmark-the cementoenamel junction (CEJ)-to the base of the pocket. CAL is the gold standard for determining the true extent of periodontal tissue destruction.

Calculations for Three Clinical Scenarios:

To determine CAL, the clinician must measure both the probing depth (PD) and the position of the gingival margin relative to the CEJ.

Scenario 1: The Gingival Margin is at the CEJ

When the gingival margin sits exactly at the level of the CEJ, no recession or overgrowth is present.

• Formula: CAL = Probing Depth (PD)
• Example: If the PD is 4 mm and the margin is at the CEJ, the CAL is 4 mm.

Scenario 2: Gingival Recession (Margin is Apical to the CEJ)

When the gingival margin has receded below the CEJ, exposing the root surface, the recession is measured as a positive value (distance from the CEJ to the gingival margin).

• Formula: CAL = Probing Depth (PD) + Gingival Recession
• Example: If the PD is 5 mm and the gingival recession is 3 mm, the CAL is calculated as: CAL = 5 mm + 3 mm = 8 mm

Scenario 3: Gingival Enlargement/Hyperplasia (Margin is Coronal to the CEJ)

When the gingiva is swollen, overgrown, or has not fully receded (e.g., drug-induced gingival hyperplasia or active inflammation), the gingival margin sits above the CEJ. The distance from the CEJ to the margin is measured.

• Formula: CAL = Probing Depth (PD) - Gingival Margin Height (Coronal to CEJ)
• Example: If the PD is 6 mm and the gingival margin sits 2 mm coronal to the CEJ (covering it), the CAL is calculated as: CAL = 6 mm - 2 mm = 4 mm

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Bleeding on Probing (BoP)

Bleeding on probing (BoP) is recorded immediately after the walking stroke is completed at each site. BoP indicates active inflammation in the connective tissue of the pocket wall, where the sulcular epithelium has become micro-ulcerated.

• Clinical Significance: While BoP has a low positive predictive value for future attachment loss (approximately 30%), it has an exceptionally high negative predictive value (98%). This means that a site that does not bleed on probing is highly stable and unlikely to undergo further attachment loss.

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Tooth Mobility Assessment

Mobility is assessed using the ends of two metal instrument handles (never fingers, as they cushion the movement) to apply alternating forces in a facial-lingual direction. The Miller Mobility Index is used for classification:

• Class I: Slight mobility; up to 1.0 mm of horizontal displacement in a facial-lingual direction.
• Class II: Moderate mobility; greater than 1.0 mm of horizontal displacement in a facial-lingual direction, with no vertical mobility.
• Class III: Severe mobility; greater than 1.0 mm of horizontal displacement combined with vertical mobility (the tooth can be depressed or rotated in its socket).

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Furcation Involvement

Furcation involvement refers to bone loss in the space between the roots of multi-rooted teeth: bifurcated mandibular molars (mesial and distal roots) and trifurcated maxillary molars (mesiobuccal, distobuccal, and palatal roots). A curved, blunt Naber's probe is used to navigate the furcation entrances.

Glickman's Classification of Furcation:

1. Class I (Incipient): Early bone loss in the furcation area. The Naber's probe can detect the fluting of the root entrance, but cannot enter the furcation itself. No radiographic signs of bone loss are visible.
2. Class II (Moderate): Bone loss allows the probe to enter the furcation horizontally under the roof of the furcation, but it cannot pass through to the opposite side. Radiographs may show slight radiolucency.
3. Class III (Severe): Interradicular bone loss is complete. The Naber's probe can pass completely through the furcation from one side to the other (buccal to lingual in mandibular molars; between the roots in maxillary molars). The furcation entrance remains covered by gingival tissue. A distinct radiolucency is visible on radiographs.
4. Class IV (Severe/Exposed): Same as Class III (probe passes completely through), but the furcation is clinically visible and exposed to the oral cavity due to gingival recession.