Bruxism, Occlusal Overload and Non-Carious Cervical Lesions (Abfraction)

The abfraction hypothesis was first formulated by dental researchers Lee and Eakle in 1984 and later refined by Grippo. The theory is grounded in basic engineering mechanics: teeth are not completely rigid rods; they possess a degree of microscopic flexibility.

When an individual grinds their teeth or exerts heavy lateral biting forces during chewing, non-axial (sideways) loads bend the tooth crown relative to the firmly embedded root. The fulcrum—the pivot point where bending stress is highest—is situated precisely at the cervical margin (the cementoenamel junction).

Nocturnal clenching and grinding generate massive lateral and oblique forces that flex teeth along their long anatomical axes. These intense biomechanical stresses concentrate at the narrow cervical fulcrum near the cementoenamel junction, fracturing microcrystalline enamel rods.

Modern clinical consensus recognizes that pure abfraction rarely acts in isolation. Rather, cervical notches result from a destructive synergy termed the "multifactorial triad": stress (abfraction), friction (toothbrush abrasion), and biocorrosion (acid erosion).

Biomechanical clenching creates microscopic cracks within the brittle enamel crystals and softer dentin. Once cracked, the weakened mineral structure is easily scrubbed away by daily toothbrushing or dissolved by dietary acids (citrus, soda, wine) and gastric reflux, carving deep, sharp-edged wedge defects.

The resulting wedge-shaped non-carious cervical lesions, known as abfractions, frequently occur in conjunction with localized gingival recession. The continuous micro-flexure of the tooth structure disrupts the adjacent junctional epithelial attachment and accelerates margin detachment.

Addressing abfraction-related recession requires managing both the biomechanical cause and the anatomical damage. The first line of defense is a custom hard acrylic occlusal splint (nightguard). The nightguard distributes nocturnal clenching forces evenly across all teeth, eliminating flexure.

If the cervical notch is sensitive or threatens pulp vitality, dentists restore the defect using flexible microfilled composites or resin-modified glass ionomer cements. These materials have a low modulus of elasticity, allowing them to bend slightly with the tooth during chewing without debonding.

Fabricating a custom dual-laminate or hard acrylic nightguard distributes occlusal forces evenly across the entire dental arch, neutralizing destructive lateral torque. Managing nocturnal bruxism protects both restorative composite margins and natural periodontal tissues from ongoing mechanical failure.

Nocturnal bruxism and diurnal clenching generate tremendous non-axial forces that transmit through the clinical crowns of teeth down into the alveolar support. According to the engineering concept of tooth flexure, lateral shearing forces cause the tooth to bend minutely along its fulcrum at the cementoenamel junction (CEJ).

This cyclical flexural stress concentrates tensile and compressive forces at the cervical margin, causing brittle enamel rods and underlying dentin crystals to fatigue, crack, and dislodge—a mechanical phenomenon known as abfraction. As the cervical tooth structure hollows out, the adjacent gingival margin loses its biological collar and recedes apically.

While abfraction and toothbrush abrasion frequently co-exist in wedge-shaped cervical lesions, the primary underlying driver in bruxers is destructive occlusal overload rather than abrasive hygiene alone.

Successfully halting abfraction-related gum recession requires addressing both occlusal biomechanics and structural tooth loss. The cornerstone of non-invasive treatment is the fabrication of a custom, hard acrylic occlusal stabilization splint (nightguard) adjusted to provide mutually protected articulation.

By distributing nocturnal bite forces evenly across the entire arch and eliminating eccentric interferences, a nightguard neutralizes destructive lateral tooth flexure. Where deep wedge-shaped notches cause food impaction or sensitivity, dentists place micro-hybrid composite or glass-ionomer restorations with low modulus of elasticity to flex harmoniously with the tooth.

If soft-tissue grafting is planned to recover root coverage, periodontists coordinate graft placement with precise enamel re-contouring to ensure the soft tissue heals over a smooth, biologically receptive root surface.