Trauma From Occlusion

An inherent "margin of safety" common to all tissues permits some variation in occlusion without adversely affecting the periodontium. However, when occlusal /ones exceed the adaptive capacity of the tissues. tissue injury re-suits I'he resultant injury is termed trauma from occlusion.*

I'hus trauma from occlusion refers to the tissue injury, not the occlusal force. An occlusion that produces such injury is called a traumatic occlusionExcessive occlusal forces may also disrupt the function ot the mastieatoiy musculature and cause painful spasms, injure the temporomandibular joints, or produce excessive tooth wear, but the term trauma from occlusion is generally used in connection with injury in the periodontium.

• the term is used throughout this text to designate periodontal tissue injury produced by occlusal forces. It is also known as traumatism and occlusal trauma.

Periodontal Occlusal InterrelationshipsOcclusal Disharmonies

Fig 24 1 Stress patterns around the roots changed by shifting the direction of occlusal forces (experimental model using photoelastic analysis). A, Buccal view of an ivorine molar subjected to an axial force. The shaded fringes indicate that the internal stresses are at the root apices. B, Buccal view of ivorine molar subjected to a mesial tilting force. The shaded fringes indicate that the internal stresses are along the mesial surface and at the apex of the mesial root, (l-rom Glickman I, Roeber F, Brion M, et al: Photoelastic analysis ol internal stresses in the periodontium created by occlusal forces. | Periodontol 1970; A 1:30.)

Acute and Chronic Trauma

Trauma from occlusion may be acute or c hronic. Acute trauma from occlusion results from an abrupt occlusal impact, such as that produced by biting on a hard object (e.g., an olive pit). In addition, restorations or prosthetic appliances thai interfere with or alter the direction of occlusal forces on the teeth may induce acute trauma. The results .ire tooth pain, sensitivity to percussion, and increased tooth mobility. If the force is dissipated by a shift in the position of the tooth or by wearing away or correction of the restoration, the injury heals and the symptoms subside. Otherwise, periodontal injury may worsen and develop into necrosis accompanied by periodontal abscess formation or persist as a symptom-free chronic condition. Acute trauma can also produce cementum tears (see Chapter 2).

Chronic trauma from occlusion is more common than the acute form and is of greater clinical significance. It most often develops from gradual changes in occlusion produced by tooth wear, drifting movement, and extrusion of teeth, combined with parafunctional habits such as bruxism and clenching, rather than as a sequela of acute periodontal trauma (see Chapters 25 and 51). The features of chronic trauma fioui occlusion and their significance are discussed in the following text.

The criterion that determines whether tin occlusion is trait-matic is w he the i it produce s per'uulontal injury, not how the teeth ocilude. Any occlusion that produces periodontal injury is traumatic. Malocclusion is not necessary to produce trauma; periodontal injury may occur when the occlusion appears normal. I'he dentition may be anatomically and aesthetically acceptable but functionally injurious. Similarly, not all malocclusions are necessarily injurious to the periodontium, traumatic occlusal relationships tire referred to by such terms .is occlusal disharmony. functional imbalance, and occlusal dystrophy. These terms refer to the occlusion's effect on the periodontium, not to the position of the teeth. Because trauma from occlusion refers to the tissue injury rather than the occlusion, an increased occlusal force is not traumatic if the periodontium can accommodate it.

Primary and Secondary Trauma from Occlusion

Trauma from occlusion may be caused by alterations in occlusal forces, reduced capacity of the periodontium to withstand occlusal forces, or both. When trauma from occlusion is the result of alterations in occlusal forces, it is called primary trauma from occlusion. When it results from reduced ability of the tissues to resist the occlusal forces, it is known as secondary trauma from occlusion.

Primary trauma from occlusion occurs if trauma from occlusion is considered the primary etiologic factor in periodontal destruction and it the only local alteration to which a tooth is subjected is from occlusion. Examples include periodontal injury produced around teeth with a previously healthy periodontium following lithe insertion ot a "high filling," 2) the insertion ot a prosthetic replacement that creates excessive forces on abutment and antagonistic teeth. *) the drifting movement or extrusion of teeth into spaces created by unreplaced missing teeth, or 4) the orthodontic movement of teeth into functionally unacceptable positions. Most studies on experimental animals ot the effect of trauma from occlusion have examined the primary type of trauma, c hanges produced by primary trauma do not alter the level of connective tissue attachment and do not initiate pocket formation. I his is probably because the supracre-stal gingival fibers are not affected and therefore prevent apical migration ot the jutu lional epithelium.

Secondary trauma from inclusion ou urs when the adaptive capac itv ot the tissues to withstand occlusal forces is impaired by bone loss resulting from marginal inflammation. This reduces the periodontal attachment area and alters the leverage on the remaining tissues. The periodontium becomes more vulnerable to injury, and previously well-tolerated occlusal forces become traumatic.

l ig. 24-2 depicts three different situations on which excessive occlusal forces can be superimposed:

1. Normal periodontium with normal height of bone

2. Normal periodontium with reduced height of bone

Marginal periodontitis with reduced height of hone

I he first case is an example of primary trauma from occlusion, whereas the last two represent secondary trauma from occlusion. I he effects ot trauma Irom occlusion in these different situations an- analyzed in the following discussion.

Ii has been found in experimental animals that systemic disorders c.ui reduce tissue resistance and that previously tolerable forces may become excessive.50"1 This could theoretically represent another mechanism by which tissue resistance to increased forces is lowered, resulting in secondary trauma from occlusion.

Periodontal Hesponse to External Forces ■ (MAIM IK 24 373

Traumatic Forces Periodontium

Fig. 24-2 Traumatic forces can occur on A, normal periodontium with normal height of bone; B, normal periodontium with reduced height of bone; or C, marginal periodontitis with reduced height of bone.

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Responses

  • WOLFGANG OSTERHAGEN
    How trauma from occlusion can be classified as chronic and acute?
    3 years ago

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