Occlusal trauma is the damage to teeth when an excessive force is acted upon them and they do not align properly.When the jaws close, for instance during chewing or at rest, the relationship between the opposing teeth is referred to as occlusion. When trauma, disease or dental treatment alters occlusion by changing the biting surface of any of the teeth, the teeth will come together differently, and their occlusion will change. When that change has a negative effect on how the teeth occlude, this may cause tenderness, pain, and damage to or movement of the teeth. This is called traumatic occlusion.Traumatic occlusion may cause a thickening of the cervical margin of the alveolar bone and widening of the periodontal ligament, although the latter can also be caused by other processes. Signs and symptoms
Clinically, there is a number of physiological results that serve as evidence of occlusal trauma:,
Progressive Tooth mobility
Fremitus
Tooth migration
Pain
Thermal sensitivity
Pain on chewing or percussion
Wear facets

Diagnosis
Microscopically, there will be a number of features that accompany occlusal trauma:
Hemorrhage
Necrosis
Widening of the periodontal ligament, or PDL (also serves as a very common radiographic feature)
Bone resorption
Cementum loss and tearsIt was concluded that widening of the periodontal ligament was a "functional adaptation to changes in functional requirements". Primary vs. secondary
There are two types of occlusal trauma, primary and secondary.
Paraneoplastic pemphigus (PNP)  is an autoimmune disorder stemming from an underlying tumor. It is hypothesized that antigens associated with the tumor trigger an immune response resulting in blistering of the skin and mucous membranes. While patients with malignant and benign tumors are both at risk, malignancy is associated with high mortality rates (near 90%). Current treatment focuses on general wound healing and administering corticosteroids, which has not demonstrated a high success rate. Recent research developments aim to treat the underlying tumor in order to alleviate the symptoms of PNP. Signs and symptoms
While the presence of lesions is the denominator among patients with PNP, the characteristics of the lesions differ. The five clinical presentations of lesions associated with PNP include:

"Pemphigus-like": Flaccid blister (discrete), crusts over the raw exuding skin lesions
"Pemphigoid-like": Tense blister(s) on brick red erythema
"Erythema multiforme-like": Severe polymorphic skin and/or mucous membrane lesions
"Graft-vs.-host disease-like": Widespread lichenoid eruption with severe mucous membrane involvement
"Lichen planus-like": Small red flat-topped scaly papulesIt is most common that mucous membrane lesions of the oral cavity are presented first. They can involve the oropharynx, nasopharynx, tongue, and vermilion (red portion) of the lips. They are also known to develop in the conjunctiva of the eye, anogenital (perineum) region, and esophagus. Cutaneous lesions tend to follow the onset of mucosal lesions. The blisters often erupt in waves, usually affecting the upper trunk, head, neck, and proximal extremities. Pemphigoid-like lesions are seen more often on the extremities.