Loss of Vertical Dimension of Occlusion / Bite Collapse
Figure 1: Loss of the molars and second bicuspids, followed by tipping of the remaining teeth, produced a collapsed bite in the patient illustrated here. The arrows demonstrate the loss of interocclusal space which would be required to fit properly sized upper and lower teeth. Such patients can present significant complexities for restoring their dentitions, facial proportions, and temporomandibular joint function; and doing so may require the involvement of surgical, restorative and orthodontic procedures.
Bite collapse (also known as loss of vertical dimension of occlusion) occurs in one of two situations. In the first, the patient grinds their teeth so aggressively, and reduces the biting surfaces so extensively that the upper and lower jaws rotate closer together than normal (Figure 2). It is important to note that there is significant professional literature refuting that excess wear leads to bite collapse, citing the tendency of teeth to move toward each other (extrude) as they wear. However, aggressive tooth grinding can certainly destroy tooth structure at a greater rate than extrusion can compensate for.
Bite collapse can also happen in patients who do not grind their teeth. This occurs when enough teeth are lost that the remaining teeth and supporting (alveolar) bone are unable to withstand even normal biting forces, and begin to tip sideways, resulting in over-closure of the jaws (collapsed bite).
Causes of multiple tooth loss include extensive tooth decay (caries) and periodontal disease. If the teeth in one jaw no longer have opposing teeth in the other jaw to bite against, they will often extrude (supererupt). Sometimes they can keep extruding until they are functioning on the gums of the opposing jaw. Generally, as they extrude, the bone and gum tissue which surrounds them extrudes along with them. The result is a dental bite relationship which requires complex rehabilitation to correct. This can involve many of the surgical and restorative procedures available to dentists.
Figure 2: Severe attrition of this habitual tooth grinder (bruxer) has led to bite collapse.
Severe attrition like that shown in Figure 2 can be a serious problem. It can result in damage to the jaw joints (TMJs); severe pain or dysfunction in the jaw joints (TMJ dysfunction); frequent muscle tension headaches; excessive muscle contraction forces as the closing muscles of the jaw shorten (which can accelerate the destruction); tooth fractures and tooth loss; aggravation of periodontal disease if present (secondary occlusal trauma); shortening of the lower face height (which can change one’s appearance, although it may not be obvious to a casual observer); an inverted smile (corners of the mouth sag); a toothless smile; frequent cracking or chapping at the corners of the mouth (angular cheilitis); and problems chewing.
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