24.7 Furcation Involvement, Mobility and Occlusal Trauma
Key Takeaways
- Furcations are probed with a curved Nabers probe; mandibular molars are probed buccally and lingually, maxillary molars also from the palatal aspect.
- Hamp degree I is horizontal loss under 3 mm, degree II exceeds 3 mm but is not through-and-through, and degree III is through-and-through.
- Miller grade 1 mobility is horizontal movement between 0.2 mm and 1.0 mm, grade 2 exceeds 1.0 mm and grade 3 includes vertical depressibility.
- Primary occlusal trauma is excessive force on a normal periodontium; secondary occlusal trauma is normal force on a reduced periodontium.
- Occlusal trauma alone does not cause attachment loss but can accelerate it in the presence of inflammation.
5. Furcation Involvement, Tooth Mobility, and Occlusal Trauma
Furcation Assessment & Hamp's Classification
Multi-rooted teeth (maxillary first/second molars, maxillary first premolars, and mandibular molars) are vulnerable to furcation invasion. Furcations must be assessed using a curved, calibrated Nabers probe.
- Mandibular Molars: Bifurcated roots; probed from the buccal and lingual aspects.
- Maxillary Molars: Trifurcated roots (Mesiobuccal, Distobuccal, Palatal); probed via three distinct entrances:
- Buccal entrance: Located between the mesiobuccal and distobuccal roots.
- Mesial entrance: Located between the mesiobuccal and palatal roots; must be probed from the palatal aspect because the mesial furcation entrance sits predominantly in the palatal two-thirds of the interproximal embrasure.
- Distal entrance: Located between the distobuccal and palatal roots; probed from either buccal or palatal aspects (midway interproximally).
According to the widely accepted Hamp et al. (1975) Classification:
- Degree I (Class I): Horizontal loss of periodontal tissue support $< 3\text{ mm}$ into the furcation entrance. Nabers probe detects the fluting/con cavity but cannot penetrate deeper than 3 mm.
- Degree II (Class II): Horizontal loss of periodontal support $> 3\text{ mm}$ into the furcation, but not encompassing the total width of the furcation. The probe does not pass completely through to the opposing side.
- Degree III (Class III): Horizontal through-and-through destruction of periodontal supporting tissue in the furcation. The Nabers probe passes completely through from one entrance to the opposing entrance (e.g., from buccal to lingual in a lower molar, or between mesiopalatal and distopalatal entrances in an upper molar).
Tooth Mobility Grading (Miller's Classification)
Tooth mobility must be tested using the rigid blunt ends of two dental instrument handles (e.g., mirror handle and probe handle), rocking the tooth gently buccolingually. Never use gloved fingers, which flex and yield misleading assessments.
According to the Miller (1950) Classification:
- Grade 1: Horizontal crown displacement between $0.2\text{ mm and }1.0\text{ mm}$ in a buccolingual direction.
- Grade 2: Horizontal crown displacement exceeding $1.0\text{ mm}$ in a buccolingual direction, without vertical displacement.
- Grade 3: Severe horizontal displacement exceeding $1.0\text{ mm}$ accompanied by vertical depressibility or rotation within the alveolar socket.
Occlusal Trauma: Primary vs Secondary
Occlusal trauma refers to injury resulting in tissue changes within the periodontal attachment apparatus (PDL, alveolar bone, cementum) caused by occlusal forces.
| Feature | Primary Occlusal Trauma | Secondary Occlusal Trauma |
|---|---|---|
| Periodontal Support | Normal, intact periodontium (normal bone height and attachment levels) | Reduced periodontium (pre-existing attachment and alveolar bone loss) |
| Nature of Occlusal Forces | Excessive / abnormal forces (e.g., high restoration, heavy bruxism, clenching) | Normal or excessive forces acting on a weakened, reduced apparatus |
| Effect on Attachment Level | Does NOT cause attachment loss or periodontal pocket formation | Does NOT initiate periodontitis, but accelerates progression of existing pockets |
| Radiographic Signs | Symmetrical, funnel-shaped widening of the PDL space; hypercementosis; osteosclerosis | Advanced angular / vertical osseous defects; widened PDL space; root resorption |
| Reversibility | Fully reversible once excessive force is removed (PDL narrows; mobility resolves) | Mobility may persist; requires splinting if mobility impairs masticatory function |
[!CAUTION] Clinical Governance Rule on Occlusal Adjustment: Prophylactic occlusal adjustment or indiscriminate grinding of natural teeth in the absence of primary trauma signs (fremitus, widened PDL, tenderness) is strictly contraindicated. Occlusal adjustment does not prevent or cure periodontitis. Periodontitis is caused by microbial plaque biofilm, not occlusal forces.
6. Clinical Traps, Pitfalls, and Worked Scenarios
[!CAUTION] Clinical Trap: Mismanagement of BPE Code 3 vs Code 4 Sextants: A clinician records BPE scores of
2 1 2 / 3 2 2. Recognizing Code 3 in the lower anterior sextant, the clinician immediately embarks on full-mouth 6-point charting across all six sextants. This violates BSP clinical protocol, generating unnecessary clinical burden and NHS fee errors. A highest BPE score of 3 warrants Step 1 therapy followed by 6-point charting only in that specific lower anterior sextant. Conversely, if the grid had read2 1 2 / 4 2 2, the presence of a single Code 4 mandates an immediate, comprehensive full-mouth 6-point chart across all six sextants before treatment commences.
[!WARNING] Clinical Trap: The Palatal Approach to Maxillary Mesial Furcations: When assessing the mesial furcation entrance of a maxillary first molar with a Nabers probe, attempting to enter from the buccal embrasure will fail to detect furcation invasion because the mesiobuccal root is broad and situated buccally. The mesial furcation entrance opens predominantly on the palatal aspect, immediately anterior to the palatal root. Always direct the Nabers probe from the palatal embrasure, hugging the cervical contour just coronal to the gingival margin.
Worked Clinical SBA Scenario
Scenario: A 56-year-old female presents for a comprehensive dental examination. BPE screening yields the following scores:
2 & 1 & 2 \\ \hline 3 & 4^* & 2 \end{array}$$ Tooth 31 in the lower anterior sextant exhibits 4 mm of gingival recession on the labial surface, with a probing pocket depth of 5 mm. In the lower anterior sextant, tooth 46 exhibits horizontal through-and-through penetration of a Nabers probe between the buccal and lingual root surfaces. *Question:* What are the immediate mandatory clinical management steps required under BSP clinical governance guidelines regarding periodontal charting, radiographic evaluation, and calculation of attachment loss at tooth 31? *Clinical Reasoning Formulation:* 1. **BPE Analysis:** The presence of **Code 4** and **Code * ** in the lower anterior sextant (and furcation involvement at 46) triggers an immediate requirement for **full-mouth 6-point periodontal charting** across all 32 teeth (all six sextants) prior to commencing treatment. It is incorrect to restrict charting to the lower anterior sextant alone. 2. **Radiographic Requirement:** Under BSP and Faculty of General Dental Practice (FGDP/CGDent) selection criteria, the presence of BPE Code 4 and furcation invasion mandates **periapical radiographs** (or vertical bitewings) of the affected sextants to assess alveolar bone architecture, vertical defects, and crown-to-root ratios. 3. **CAL Calculation for Tooth 31:** - Probing Pocket Depth (PPD) = $5\text{ mm}$. - Gingival Margin Recession = $4\text{ mm}$ apical to the CEJ. - $\text{CAL} = \text{PPD } (5\text{ mm}) + \text{Recession } (4\text{ mm}) = \mathbf{9\text{ mm}}$ of clinical attachment loss. 4. **Furcation Assessment at 46:** Horizontal through-and-through penetration across the total buccolingual width represents a **Hamp Degree III (Class III)** furcation involvement, carrying a guarded-to-poor long-term prognosis.A 10-year-old child presents with their parent for a routine dental check-up. The practitioner intends to conduct periodontal screening in accordance with the BSP and BSPD simplified BPE guidelines for paediatric patients. What protocol must be followed?
During a 6-point periodontal examination of tooth 21, the dental practitioner measures a probing pocket depth (PPD) of 5 mm on the mid-labial aspect. The free gingival margin has receded 3 mm apical to the cemento-enamel junction (CEJ). What is the true Clinical Attachment Loss (CAL) at this site?