A patient's periodontal chart shows the following for tooth #30 mid-buccal: probing depth = 6 mm, gingival margin = 2 mm apical to the CEJ. What is the clinical attachment level?
Choose an answer, then check it.
NBDHE Review · Periodontology (Provision of Clinical Dental Hygiene Services)
Periodontal Assessment: Clinical Parameters
On this page 7 sections
In 30 seconds
Periodontal assessment is the foundation of periodontal diagnosis and treatment planning. The NBDHE tests every component of the comprehensive periodontal examination: probing depth measurement, gingival margin position, clinical attachment level calculation, bleeding on probing, suppuration, furcation involvement, mobility, plaque and calculus assessment, and radiographic bone loss evaluation. You must understand what each parameter measures, how it is recorded, and what it means clinically. Expect 6-10 questions on periodontal assessment, including interpretation of charted findings.
The college version
Core Review
The Periodontal Examination
The comprehensive periodontal examination is the systematic collection of clinical and radiographic data to determine the presence, extent, and severity of periodontal disease. It establishes a baseline against which treatment outcomes are measured.
Probing Depth
Definition: Probing depth (PD) is the distance from the gingival margin to the base of the periodontal sulcus or pocket, measured in millimeters with a periodontal probe.
Technique:
- Use a conventional (e.g., UNC-15, Williams) or electronic pressure-sensitive probe
- Apply gentle probing force (approximately 20-25 grams — roughly the pressure needed to blanch a fingernail)
- Walk the probe circumferentially around each tooth, taking measurements at 6 sites per tooth: distofacial, facial, mesiofacial, distolingual, lingual, mesiolingual
- Record the deepest reading obtained at each site
- Measurements are typically rounded up to the nearest millimeter
Interpretation:
- 1-3 mm: Normal sulcus depth (in the absence of inflammation and bone loss)
- 4 mm or greater: May indicate a periodontal pocket
- Healthy sulcus: Histologically 0.5-2.0 mm; clinically probe may penetrate to the junctional epithelium (giving a reading of 1-3 mm)
- Pseudopocket: Deepened probing depth due to gingival enlargement without apical migration of the junctional epithelium (no attachment loss)
- True pocket: Deepened probing depth with apical migration of the junctional epithelium (attachment loss has occurred)
Critical distinction: Probing depth alone does NOT distinguish between gingivitis and periodontitis. A probing depth of 5 mm could be a pseudopocket (gingivitis with enlargement) or a true pocket (periodontitis with attachment loss). Clinical attachment level (see below) is needed to make this distinction.
Factors affecting probing depth accuracy:
- Probing force (heavy force = deeper readings, more bleeding)
- Probe diameter (thinner probes penetrate more easily)
- Inflammation (inflamed tissues offer less resistance to probing)
- Probe angulation (should be parallel to the long axis of the tooth)
- Subgingival calculus (may obstruct probe penetration)
Gingival Margin Position
Definition: The position of the gingival margin relative to the cementoenamel junction (CEJ).
Measurement:
- Measure the distance from the CEJ to the gingival margin at each site
- If the gingival margin is at the CEJ: 0 mm
- If the gingival margin is apical to (below) the CEJ: recorded as a positive number (recession)
- If the gingival margin is coronal to (above) the CEJ: recorded as a negative number (enlargement/overgrowth)
Clinical significance: The gingival margin position is essential for calculating clinical attachment level and for monitoring changes in gingival architecture over time. Gingival recession is a physical finding; it indicates displacement of the gingival margin apical to the CEJ but does not by itself indicate active disease.
Clinical Attachment Level (CAL)
Definition: CAL is the distance from the CEJ to the base of the periodontal pocket. It represents the total amount of periodontal attachment that has been lost and is the GOLD STANDARD for assessing periodontal disease severity and monitoring disease progression.
CEJ is the fixed landmark: The CEJ does not move. The gingival margin and the base of the pocket can both change over time, but the CEJ remains constant. Therefore, CAL provides the most accurate measure of cumulative periodontal destruction.
Calculation:
There are two formulas depending on the position of the gingival margin relative to the CEJ:
Case 1: Gingival margin is at or apical to the CEJ (recession present) CAL = Probing Depth + Recession
Example: PD = 5 mm, Gingival margin is 2 mm apical to CEJ (recession = 2 mm) CAL = 5 + 2 = 7 mm
Case 2: Gingival margin is coronal to the CEJ (gingival enlargement/overgrowth) CAL = Probing Depth − Gingival Enlargement
Example: PD = 7 mm, Gingival margin is 3 mm coronal to CEJ (enlargement = 3 mm) CAL = 7 − 3 = 4 mm
Case 3: Gingival margin is at the CEJ CAL = Probing Depth
Example: PD = 4 mm, GM at CEJ (0 mm recession or enlargement) CAL = 4 mm
Clinical significance of CAL:
- CAL distinguishes between a pseudopocket (deep probing depth, no CAL) and a true periodontal pocket (deep probing depth, CAL present)
- CAL is used in current AAP/EFP classification for staging periodontitis
- Changes in CAL over time indicate disease progression, stability, or improvement
Probing depth vs. CAL:
- Probing depth measures the current depth of the sulcus/pocket from the gingival margin
- CAL measures cumulative tissue destruction from the CEJ
- Probing depth can change with therapy (reduction indicates treatment response; decreases when tissues tighten)
- CAL is more stable; a gain in CAL indicates true clinical attachment gain (regeneration or new attachment)
Bleeding on Probing (BOP)
Definition: The presence or absence of bleeding within 10-30 seconds after gentle probing to the base of the sulcus/pocket.
Recording:
- Record as present (+) or absent (−) at each probing site
- BOP is usually expressed as the percentage of sites that bleed (number of bleeding sites / total sites probed × 100)
Clinical significance:
- BOP is a sign of inflammation in the connective tissue beneath the junctional and sulcular epithelium
- BOP indicates the presence of an inflammatory lesion, not necessarily active disease progression
- Absence of BOP is a reliable indicator of periodontal stability (negative predictive value >98%)
- Persistent BOP at re-evaluation indicates ongoing inflammation and may predict further attachment loss
- BOP alone does NOT diagnose periodontitis — it can occur in gingivitis and periodontitis
Limitations: BOP can be influenced by probing force, hormonal changes (pregnancy, menstruation), medications (anticoagulants), and smoking (smokers may have suppressed BOP due to vasoconstriction — nicotine effect).
Suppuration
Definition: The presence of pus or purulent exudate from a periodontal pocket, visible either spontaneously or after gentle pressure on the gingiva.
Clinical significance:
- Suppuration indicates an active, acute inflammatory process within the periodontal pocket wall
- Associated with tissue necrosis and bacterial infection
- Presence of suppuration is a sign of active disease
- May indicate the presence of a periodontal abscess
Assessment: Apply gentle finger pressure along the lateral aspect of the gingiva and observe for exudate at the gingival margin. Note the tooth, site, and character of the exudate.
Tooth Mobility
Definition: The degree of horizontal or vertical displacement of a tooth when force is applied. Mobility is assessed using the blunt ends of two instruments (e.g., mirror handle and periodontal probe handle) alternating pressure on the buccal and lingual surfaces.
Miller Classification of Mobility:
| Class | Description |
|---|---|
| Class I | Slightly more than normal (<1 mm horizontal movement) |
| Class II | Moderately more than normal (>1 mm horizontal movement, no vertical displacement) |
| Class III | Severe movement both horizontally and vertically (>1 mm horizontal + vertical depression in socket) |
Interpretation:
- Physiologic mobility (0.1-0.2 mm) is normal and occurs during mastication due to the periodontal ligament
- Pathologic mobility results from loss of supporting alveolar bone and/or widening of the periodontal ligament space due to inflammation
- Mobility is typically assessed AFTER inflammation is resolved (post-initial therapy), as inflammation alone can cause reversible mobility
- Fremitus: palpable or visible movement of a tooth during functional (occlusal) contact. Indicates occlusal trauma. Recorded as Class I (barely palpable) to Class III (visible to the naked eye).
Differential diagnosis: Tooth mobility can also result from:
- Trauma (tooth fracture, luxation)
- Periapical pathology (large periapical lesion)
- Orthodontic treatment (physiological)
- Loss of adjacent teeth
- Parafunctional habits (bruxism)
Furcation Involvement
Definition: Bone loss extending into the bifurcation or trifurcation area of multi-rooted teeth, resulting in exposure of the furcation area to the oral environment or probe penetration.
Glickman Classification of Furcation Involvement:
| Class | Description |
|---|---|
| Class I | Incipient or early involvement. The furcation can be detected with a probe, but the horizontal bone loss is less than 3 mm. The furcation concavity can be felt, but the probe does not enter deeply. |
| Class II | Moderate involvement. The probe can enter the furcation but cannot pass completely through to the opposite side. Bone loss extends more than 3 mm horizontally but still has bone covering portions of the furcation. A "cul-de-sac" is present. |
| Class III | Through-and-through involvement. The probe can pass completely from buccal to lingual or mesial to distal. However, the furcation is still covered by gingival tissue (clinically "closed" but a tunnel exists beneath). |
| Class IV | Through-and-through involvement with gingival recession. The furcation is clinically visible and the probe passes completely through. The furcation is exposed to the oral cavity. |
Furcation assessment:
- Use a Nabers probe (curved, calibrated) specifically designed for furcation assessment
- Maxillary molars have three furcations: buccal, mesial, and distal
- Mandibular molars have two furcations: buccal and lingual
- Maxillary premolars may have a single furcation (between buccal and lingual roots when roots are separated)
Clinical significance of furcation involvement:
- Furcation-involved teeth have a less favorable prognosis
- Class I and II furcations may be managed with non-surgical therapy and maintenance
- Class III and IV furcations often require surgical intervention or may be considered for extraction
- Furcation anatomy (concavities, ridges, accessory canals) makes these areas difficult to debride effectively
- Furcation involvement is a component of periodontitis staging (complexity factor)
Gingival Recession
Definition: The apical displacement of the gingival margin from the CEJ, exposing the root surface.
Measurement:
- Measure from the CEJ to the gingival margin (in millimeters)
- If the GM is apical to CEJ, record as a positive number (e.g., +3 mm)
- Report the location (tooth number and surface)
Clinical significance:
- Exposed root surfaces are at risk for root caries and dentinal hypersensitivity
- Recession contributes to CAL: CAL = PD + recession
- Causes of recession include: thin gingival biotype, prominent roots, orthodontic movement outside the alveolar housing, traumatic toothbrushing, periodontal disease, frenum pull, iatrogenic factors
- Recession is NOT the same as CAL — recession only describes the gingival margin position
Plaque and Calculus Assessment
Plaque Assessment:
- O'Leary Plaque Control Record: A dichotomous (present/absent) scoring system for all tooth surfaces after disclosing solution. Score = (surfaces with plaque / total surfaces) × 100
- Silness and Löe Plaque Index: Scores 0 (no plaque) to 3 (abundant plaque) on selected teeth
- Plaque-free score: The percentage of surfaces without plaque. Used as a motivational tool and outcome measure.
Calculus Assessment:
- Record the location (supragingival or subgingival), extent (generalized or localized), and amount (slight, moderate, heavy)
- Subgingival calculus is detected with a fine explorer or periodontal probe — it feels like a rough, irregular surface
- Calculus is a contributing factor, not the primary etiologic agent — bacterial biofilm is the cause of periodontal disease
Radiographic Assessment of Periodontal Disease
Radiographs are an essential adjunct to clinical examination, not a substitute. They provide:
Radiographic findings in health and disease:
- Healthy periodontium: Intact lamina dura (thin radiopaque line around roots), alveolar crest is 0.5-2.0 mm apical to the CEJ of adjacent teeth, smooth and continuous crestal bone, distinct periodontal ligament space
- Periodontitis: Loss of lamina dura continuity, alveolar bone loss (horizontal or vertical/angular), furcation radiolucency, widened periodontal ligament space, crestal bone irregularity
Bone loss patterns:
- Horizontal bone loss: Bone loss is relatively perpendicular to the long axis of the teeth. Bone level is reduced uniformly. More common.
- Vertical (angular) bone loss: Bone loss is oblique to the long axis of the tooth. Creates an intrabony defect — one, two, or three-walled depending on the number of osseous walls remaining. Often associated with local factors (overhanging restorations, open contacts, food impaction).
Limitations of radiographs:
- Radiographs are two-dimensional representations of three-dimensional anatomy — they cannot show buccal or lingual bone loss
- Radiographs underestimate bone loss (30-50% of alveolar bone mineral content must be lost before it is detectable radiographically)
- Radiographs do not reveal soft tissue morphology (pocket depth, gingival inflammation)
- Radiographs cannot distinguish between treated/stable periodontitis and active disease
Clinical Application
A periodontal chart reveals: Tooth #19 — PD: 5 mm (mid-buccal), GM: +2 mm (recession), BOP: +, furcation: Class II (buccal), mobility: Class I.
Calculations for #19 mid-buccal:
- CAL = PD + Recession = 5 + 2 = 7 mm
- This represents significant attachment loss (7 mm)
- The tooth has moderate mobility (Class I) and furcation involvement (Class II buccal), indicating moderate complexity
- Under the current AAP/EFP classification, the CAL of 7 mm and furcation involvement contribute to staging determination
Common Traps
- TRAP: Using probing depth as a measure of CAL or disease severity. Probing depth alone does not distinguish gingivitis from periodontitis. A 4 mm pseudopocket (no CAL) is less severe than a 3 mm true pocket with 2 mm of recession (CAL = 5 mm).
- TRAP: Forgetting to subtract gingival enlargement when calculating CAL. If the GM is coronal to the CEJ, part of the probing depth is due to enlargement, not attachment loss.
- TRAP: Confusing mobility and fremitus. Fremitus is detected during function (occlusal contact). Mobility is assessed by manual manipulation.
- TRAP: Relying on radiographs alone for periodontal diagnosis. Radiographs do not show pocket depth, BOP, or suppuration.
- TRAP: Not recognizing that smoking suppresses BOP. A smoker may have significant inflammation without bleeding — do not be falsely reassured.
Eli explains
The same idea, in plain words
Explain it like I’m 10
When we check your gums, we are like a surveyor measuring a property. We use a tiny ruler (periodontal probe) to measure three things: (1) how deep the space is between your gum and tooth (pocket depth), (2) where your gum sits relative to the "property line" (the CEJ — the line where the enamel of the tooth meets the root), and (3) how much attachment has actually been lost — which is the most important number. If your gum has receded 2 mm and the pocket is 5 mm deep, the true amount of damage is 7 mm (5 + 2). We also check for bleeding (which means inflammation), pus (which means active infection), loose teeth (mobility), and bone loss in the furcation — the spot where the roots of back teeth split. All these measurements together tell us how healthy your gums are, how much damage has been done, and whether the disease is active or under control.
Key takeaways
- Probing depth = GM to base of sulcus/pocket
- CAL = CEJ to base of sulcus/pocket (gold standard for disease severity)
- CAL = PD + recession (GM apical to CEJ)
- CAL = PD − enlargement (GM coronal to CEJ)
- BOP absence = strong indicator of stability (NPV >98%)
- Suppuration = active disease indicator
- Furcation Class I = incipient (<3 mm), II = cul-de-sac, III = through-and-through (tissue-covered), IV = exposed
- Mobility Class I = <1 mm horizontal, II = >1 mm horizontal, III = horizontal + vertical
- Recession ≠ CAL — recession is only the GM position component
- Question 1: A patient's periodontal chart shows the following for tooth #30 mid-buccal: probing depth = 6 mm, gingival margin = 2 mm apical to the CEJ. What is the clinical attachment level?
- ---
- Question 2: A patient's periodontal chart shows tooth #9 mid-buccal: probing depth = 7 mm, gingival margin = 3 mm coronal to the CEJ (gingival enlargement). What is the clinical attachment level?
- ---
- Question 3: A Nabers probe can enter the furcation of tooth #3 approximately 4 mm but cannot pass through to the lingual side. This is classified as:
Check yourself
3 review questions from the chapter. Try each one, then open the answer.
A. 4 mm B. 6 mm C. 8 mm D. 2 mm
Show answer
C. When the gingival margin is apical to the CEJ (recession present): CAL = PD + Recession = 6 + 2 = 8 mm.
A. 10 mm B. 7 mm C. 4 mm D. 3 mm
Show answer
C. When the gingival margin is coronal to the CEJ (enlargement): CAL = PD − Enlargement = 7 − 3 = 4 mm. The pocket appears deep (7 mm) because of gingival enlargement, but the true attachment loss is only 4 mm.
A. Furcation Class I B. Furcation Class II C. Furcation Class III D. Furcation Class IV
Show answer
B. Class II furcation involvement allows probe penetration of >3 mm but the probe cannot pass completely through to the opposite side (a "cul-de-sac" exists). Class I is incipient (<3 mm). Class III is through-and-through but covered by gingiva. Class IV is through-and-through and clinically visible.
Quick check
3 questions here. Answers stay hidden until you check.
A patient's periodontal chart shows tooth #9 mid-buccal: probing depth = 7 mm, gingival margin = 3 mm coronal to the CEJ (gingival enlargement). What is the clinical attachment level?
Choose an answer, then check it.
A Nabers probe can enter the furcation of tooth #3 approximately 4 mm but cannot pass through to the lingual side. This is classified as:
Choose an answer, then check it.
Study tools & related lessonsYou’ll learn to · Related
You’ll learn to
- Describe the technique, purpose, and interpretation of each periodontal assessment parameter
- Accurately calculate clinical attachment level from probing depth and gingival margin position
- Classify furcation involvement using the Glickman classification system
- Classify tooth mobility using the Miller system
- Distinguish between gingivitis and periodontitis based on assessment findings
- Interpret radiographs for periodontal bone loss
- Document comprehensive periodontal findings systematically
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