Occlusal Trauma and Excessive Occlusal Forces

Clinical summary drawn from the 2017 World Workshop narrative review by Fan & Caton (Occlusal trauma and excessive occlusal forces Narrative review, case definitions, and diagnostic considerations, J Periodontol 2018). Focus is on the practical takeaways, especially the management of abfraction.

Case Definitions (Brief)

• Occlusal trauma — injury to the periodontium from occlusal forces exceeding its adaptive capacity. Can only be confirmed histologically; clinically diagnosed via surrogate indicators (fremitus, increasing mobility, widened PDL space, wear facets, tooth migration, discomfort on chewing).
• Primary occlusal trauma — injury to a periodontium of normal height/support from excessive forces (e.g., a high restoration, parafunction).
• Secondary occlusal trauma — injury to a periodontium of reduced height/support from forces that may be normal or excessive (e.g., a periodontitis-compromised tooth that can no longer tolerate normal load).
• Fremitus — palpable functional mobility of a tooth in occlusal function; a key clinical sign of occlusal trauma.

Effect on the Periodontium

• Excessive occlusal forces do NOT initiate periodontitis or cause loss of connective tissue attachment. This is the consistent finding across the classic animal models (squirrel monkey, beagle dog).
• In the absence of inflammation, occlusal trauma produces increased mobility and reversible loss of bone density only — no irreversible attachment loss. Removing the force reverses the bone density loss.
• When occlusal trauma is superimposed on plaque-induced periodontitis, there is only weak evidence it may accelerate attachment loss (a cofactor, not a cause).
• Clinical implication: occlusal therapy is not a substitute for plaque control and conventional periodontal treatment. It is an adjunct to reduce mobility, improve comfort and masticatory function, and possibly enhance healing outcomes when frank signs of occlusal trauma are present.

Abfraction (Main Focus)

What it is

• Abfraction = a non-carious cervical lesion (NCCL) proposed to arise from occlusal loading rather than from caries, erosion, or abrasion. It is the wedge/notch-shaped defect at the cervical (CEJ) region.

Proposed mechanism vs the evidence

• Mechanism (theory): occlusal/eccentric loading generates cervical tensile and compressive stress concentrated at the CEJ, causing flexure of the tooth and micro-fracture of the cervical enamel and dentin.
• Evidence is weak and contested: support comes mainly from finite element analysis (FEA), which does not replicate a real clinical situation — different studies assume different tissue properties and arbitrary force magnitudes/directions/durations.
• Cross-sectional studies show associations (with bruxism, wear facets, premature contacts, group function) but do not establish causation; lesion size has not correlated with the extent of occlusal wear.
• A split-mouth study found eliminating excursive interferences did not slow NCCL progression. The review concludes abfraction remains a biomechanically based theoretic concept, not supported by adequate clinical evidence, and there is no credible evidence it causes gingival recession.
• Practical reading: NCCLs are almost always multifactorial (stress + erosion + abrasion). Don’t attribute a cervical lesion to occlusion alone.

Clinical management

• Diagnose the etiology first. Assess for erosion (diet, GORD, eating disorders), abrasion (toothbrushing technique/force), and occlusal/parafunctional contribution before deciding to ignore or restore. Many NCCLs are non-progressive and can simply be monitored if asymptomatic and not deepening.
• Address the load, not just the lesion. Because the etiology involves the occlusal/biomechanical environment, restoring the defect without managing the cause predisposes to repeated restoration failure (debonding, marginal breakdown) at the high-flexure cervical site.
  • Occlusal adjustment: selectively eliminate premature contacts and excursive interferences directing eccentric load onto the affected tooth.
  • Manage parafunction/bruxism: an occlusal splint/night guard to reduce nocturnal loading.
  • Modify co-factors: erosion and abrasion control (diet/acid advice, atraumatic brushing, desensitising/fluoride agents).
• Restoration considerations (when restoring for sensitivity, esthetics, structural loss, or active progression):
  • Prefer flexible, well-bonding materials at the cervical margin — resin-modified glass ionomer or a low-modulus/flowable composite tolerate cervical flexure better than rigid restoratives.
  • Conserve tooth structure; ensure good moisture control and bonding to dentin/enamel margins.
  • Why aggressive restoration alone fails: if the excessive/eccentric occlusal load is not addressed, the same cervical stresses that contributed to the lesion will continue to flex the tooth and stress the restoration margin, leading to recurrent loss. Load management + co-factor control should accompany any restorative repair.

Related Reference Material

• See MOC Periodontology for the broader periodontal context.
• Pairs with the occlusion lecture: L6 The role of Occlusion in Periodontal therapy.