In occlusal trauma, the etiologic factor is any force in excess of the adaptive capacity of the periodontium, the morbid pathobiologic event is injury within the periodontal ligament and alveolar bone, and the signs and symptoms are pain, mobility and/or fremitus, pathologic migration of teeth, excessive occlusal wear, and widening of the periodontal ligament space in radiographs.

As defined in the Glossary of Periodontal Terms, occlusal trauma is the functional loading of teeth (force is primary etiologic factor), usually off-axis, that is of sufficient magnitude (excess of the adaptive capacity) to induce changes to the teeth (eg, fractures, occlusal wear) or supporting structures (inflammation in the periodontal ligament and alveolar bone, also known as the lesion of trauma from occlusion). The changes may be temporary (reversible) or permanent (irreversible).

What is Adaptive Capacity? What Factors Affect the Adaptive Capacity?

Adaptive capacity is the ability of the teeth and tissues of the periodontium to sustain the effects of, or adapt to, forces acting on the periodontium without injury. The adaptive capacity is affected quantitatively and qualitatively by local and systemic contributing factors. When it is exceeded, occlusal traumatism occurs.

The etiologic forces that produce occlusal traumatism may not always be occlusal in nature, but they may be generated by orthodontic or prosthodontic appliances and/or habits of compulsion, such as pipe smoking or lingernail biting. The more inclusive designation, periodontal traumatism, is preferred by some over occlusal traumatism because it allows for nonocclusal forces and occlusal forces as etiologic factors.

What Is the Nature of the Injury to the Periodontal Attachment Apparatus Produced by Forces Acting on Teeth? What Is Primary and Secondary Occlusal Trauma?

The injury to the periodontium caused by forces acting on teeth is called the lesion of trauma from occlusion or more simply, occlusal trauma.

• The lesion of occlusal trauma is located within the periodontal ligament in areas where the ligament is either under pressure (crushed) or under tension (torn). The crush or tear produces a physical injury resulting in local necrosis of the periodontal ligament and a typical inflammatory response. The histologic appearance of the periodontal ligament is described as hyalinization, or a decrease in the cellular component of the tissue. Resorption of nearby alveolar bone also occurs as an outcome of the inflammation. The resorption will occur on the periodontal ligament side of the alveolar bone proper with mild injury (frontal resorption) and/or on the marrow surfaces of the supporting alveolar bone (rear resorption). The degree of necrosis, inflammation, and resorption will depend upon the amount of force acting on the teeth and the adaptive capacity of the periodontium.

• Primary occlusal trauma is the injury resulting in tissue changes (injury to the attachment apparatus) from excessive (in excess of the normal adaptive capacity of the periodontium) occlusal (and other) forces to a tooth or teeth with a healthy, anatomically normal, periodontium in a systemically well patient. Primary occlusal trauma is usually reversible once the forces that produced it are controlled.

• Secondary occlusal trauma is the injury resulting in tissue changes (injury to the attachment apparatus) from normal or excessive (in excess of the reduced adaptive capacity of the periodontium) occlusal (and other) forces to a tooth or teeth with reduced support. Because these same contributing factors that reduced the adaptive capacity of the periodontium may be difficult to control or change, secondary occlusal trauma is difficult to reverse following force control.

Does the Injury in the Periodontium Produced by occlusal trauma on Teeth Contribute in Any Way to Periodontal Attachment Loss?

The marginal inflammatory lesion of periodontitis and the lesion of occlusal trauma were believed to be separate processes. However, it has been hypothesized that the two processes become co-destructive in the transseptal and alveolar crestal fiber region of the marginal periodontium.

The suggestion that the marginal inflammation of periodontitis could be then spread into the periodontal ligament along fiber realignment caused by occlusal forces was supported in animal studies.

This concept of periodontal pathogenesis conflicted critically with the classic periodontitis model where marginal inflammation was depicted as following perivascular connecfive tissue directly into alveolar bone marrow, and where the periodontal ligament was typically free of inflammation.

The projected outcome of this “co-destructive” process was the formation of angular bony defects and infrabony pockets seen commonly in periodontitis.

Studies in both animals and humans have not been able to completely demonstrate the role of occlusal trauma in periodontitis. While it is unclear whether potentially destructive occiusal contacts have any impact on the severity of periodontitis, there is agreement that two of the recognized signs of occlusal trauma (eg, mobility and widened PDL spaces) are associated with greater amounts of attachment loss, pocket depth, and bone loss.

What Are the Clinical Signs and Symptoms of Occlusal Trauma?

The clinical signs and symptoms of injury in the periodontal ligament are commonly:

1. Pain or discomfort around one or more teeth on percussion, function,and/or parafunction. Pain is one of the four cardinal signs of inflammation (dolor/pain, calor/heat, rubor/redness, and tumor/swelling). Pain then is a sign of inflammation in the periodontal ligament.

2. Tooth mobility as determined with bidigital manipulation of teeth using the handles of 2 hand instruments. One handle is placed on the buccal surface and the other is placed on the lingual surface of clinical crowns. Tooth mobility is defined as visibly perceptible movement of a tooth away from its normal position when a light force is applied.

Tooth mobility may be physiologic (ie, horizontal movement limited to the width of the periodontal ligament), or pathologic (ie, horizontal and/or vertical movement beyond the expected boundaries of the periodontal ligament).

Mobility occurs when fibers of the periodontal ligament are injured or destroyed by inflammation resulting from excessive forces acting on teeth. It will also occur when the adaptive capacity of the periodontium has been altered by marginal inflammation or systemic disease. Mobility is commonly observed when a tooth has reduced periodontal attachment.

The Miller classification scheme for tooth mobility in occlusal trauma  is as follows:

– Grade (degree) I. The slightest distinguishable movement in a horizontal direction. Tooth mobility is classified as physiologic mobility.

– Grade (degree) II. Movement in a horizontal direction of a tooth within 1 mm of its normal position.

– Grade (degree) Ill. Movement of a tooth in a horizontal direction greater than 1 mm from its normal position. Grade Ill mobility also includes teeth that are depressible and/or can be rotated in their periodontal support.

3. Fremitus as determined by palpable or visible movement of teeth under vertical (axial) or horizontal (nonaxial) occlusal forces. Fremitus is detected using fingertips placed on the crowns of teeth while the patient occludes. Fremitus is functional mobility.

4. Pathologic migration of teeth. Pathologic migration of teeth usually occurs when teeth have lost their normal periodontal support due to periodontitis and subsequently migrate from their normal position in the dentition in response to occlusal and nonocclusal forces.

5. Tooth loss

6. Posterior bite collapse. Posterior bite collapse is the product of tooth loss and pathologic migration.

7. Widened periodontal ligament spaces around affected teeth in radiographs. Widened periodontal ligament (POL) spaces usually indicate that an adaptive response has occurred either to excessive force on a normal periodontium or to normal or excessive forces on a reduced periodontium. Widened PDL spaces together with an intact laminadura suggest that repair occurred following injury.

What is the Basis for Force Control and Occlusal Therapy in Occlusal trauma?

The essence of occlusal therapy is to treat the lesion of trauma from occlusal trauma and to create an environment that will allow the injured attachment apparatus to repair itself within the limits imposed by the adaptive capacity of the host. It is not a form of therapy for periodontitis.

There is some evidence to suggest that periodontitis patients who receive periodontal inflammatory disease control therapy along with ocdusal adjustment will display minor (<1 mm) gains in attachment compared to those who did not receive occlusal adjustment.

Repair to the attachment apparatus will depend directly upon the effectiveness of force control and indirectly upon the effectiveness of improvements in the adaptive capacity before force control (ie, control of marginal inflammation and control of diabetes mellitus).

What Are the Components of a Force Control Treatment Plan for a Periodontal Patient? What Determines Which Component Is Appropriate in a Given Case? How Are the Components Sequenced?

A typical force control treatment plan for a patient with the diagnosis of generalized moderate chronic periodontitis with occlusal traumatism would be:

Re-evaluation of inflammatory disease control in occlusal trauma

After a minimum of 4-6 weeks (the time for repair of the dentogingival junction), the patient is re-examined and the results of that examination are compared with those recorded at the initial examination. This is a critical stage in treatment as decisions about the working diagnosis and continuing active therapy are made depending upon the answers to the following questions:

1. Are there any persistent signs and symptoms of gingival inflammation or debris present?

2. If so, is there anything short of periodontal surgery that can be done to improve the conditions?

3. Is there any residual tooth mobility/fremitus?

If the answer to the first and second question is no and the answer to the third question is yes, the patients working diagnosis of generalized moderate chronic periodontitis with occlusal trauma is supported, and treatment should proceed to the occlusal therapy phase.

If, however, the answer to the first and second question is yes, then considerations for improving the patients oral hygiene, refining scaling and root planing, instituting antimicrobial therapy, additional Correction of plaque retentive factors, and discussions concerning progress made in smoking cessation might be appropriate.

Assuming that the answers to the first and second questions are no and the answer to the third question is yes, the next step in treatment is to determine what is responsible for the mobility and fremitus.

• Assessment of parafunctional occlusal habits of compulsion in occlusal trauma .

Check this video on Occlusal Trauma and its effect on teeth!!