Trauma from Occlusion

A traumatic occlusion is an occlusion that has caused injury to the teeth, muscles, or TMJ.2,5,6 A classification of primary traumatic occlusion is made when heavy occlusal forces exceed the adaptive range in a normal periodontium, causing injury to tissues and bone. A classification of secondary traumatic occlusion is made when normal occlusal forces exceed the capability of a periodontium that is already affected by periodontal disease. Trauma from occlusion does not initiate gingivitis and periodontal disease. When inflammation is present, occlusal trauma can increase tissue attachment loss and supporting bone destruction. Therefore, occlusal trauma is of interest in the diagnosis and treatment of periodontal disease.

Traumatic occlusion does not refer to a malocclusion, as described by Angle’s three classifications. Angle’s Class I, II, and III occlusion classifiy and describe the skeletal relationship of the maxillary to the mandibular teeth. Because malocclusion of the teeth may interfere with the removal of bacterial plaque, it is a factor in the attainment of good oral hygiene. Common terms used to describe mandibular function and dysfunction are listed in Box 11-1.

The occlusal relationship of the teeth is not a predictor of pain or problems in the TMJ. Common occlusal features, such as intercuspal position or midline discrepancies, do not provide the dominant factors in defining populations with TMDs.8,9

Controversy regarding the clinical significance of trauma from occlusion has existed for some time. It is now widely accepted that in the absence of marginal gingival irritation, trauma from occlusion does not produce gingival inflammation. Trauma associated with orthodontic movement of teeth is self-limiting. Self-limited mobility is greater than normal, but is based on the adaptive capacity of the periodontium. Thus, the increased mobility of the teeth is handled through periodontal adaptation to the excessive forces without causing trauma from occlusion.¹ Dentists may use this rationale when selectively grinding (adjusting) the occlusal surfaces of the teeth after periodontal therapy to create a dentition that does not produce injury. The goal is to establish an occlusal relationship that will foster a favorable periodontal response. True trauma from occlusion (trauma that exceeds the adaptive capacity of the periodontium) increases bone loss and pocket depth formation. This situation may occur with bruxism in a periodontal patient.

Certain tooth relationships can also be detrimental to the attainment of good periodontal health. Open contacts or faulty contacts between teeth can cause areas of food impaction. Food impaction is the forceful wedging of food into the periodontium by occlusal forces. The self-cleansing aspects of the dentition do not exist in these situations, and food impaction can be a contributing factor in periodontal disease.

The dental hygienist must carefully complete the clinical assessment of the patient, noting all of the gingival conditions and determining the reason for the condition, if possible. In the past, certain gingival conditions, such as recession, clefting, or thickening of the gingival margin, were thought to be caused by trauma from occlusion. These causative relationships have not been supported by research.⁴

Understanding the multifactorial origin of jaw dysfunction and how it relates to the treatment of the periodontal patient is important. When an individual can attain and maintain good oral hygiene, malocclusion is of no periodontal significance.1,5 However, most patients have difficulty with plaque removal, making malocclusion a factor to be considered in the progression of periodontal disease.

Cause

The etiology of TMDs is multifactorial. Because of the many causes, TMDs are frequently difficult to diagnosis and treat. Stress is often a factor in TMDs and patients with TMDs may have a history of other diseases, such as arthritis and psychological problems. In determining the causes of TMDs, a history of macrotrauma or microtrauma may be discovered by the clinician. A macrotrauma is usually a single event that may have caused damage to the masticatory system. Such an event could be a sports-related injury, a whiplash accident, or a fall. The patient may not relate such an event to later occlusal or TMJ pain and discomfort. Microtrauma is a number of minor habits or events that cause damage to the masticatory structures. Examples of microtrauma include bruxism and postural and oral habits.

Categories of Temporomandibular Disorders

There are four main diagnostic categories for TMD, which are listed in Box 11-2. These categories are based on criteria derived from the signs and symptoms gathered in the comprehensive TMD evaluation.^3,5,11 The first category is muscle and fascial disorders of the masticatory system. This group includes myalgia (pain in the masticatory muscles), trismus (spasm in the masticatory muscles), dyskinesia (incoordination of the jaw), bruxism (clenching or grinding), and other muscle disorders. Disorders of the TMJ, the second category, include internal derangements that impair mechanical function of the TMJ, such as arthritis. The third category includes disorders of mandibular mobility, such as ankylosis, muscular fibrosis, internal derangement, and adhesions in the joint. The fourth category, disorders of maxillomandibular growth, is less common. These disorders include neoplastic and nonneoplastic conditions.