Vertical dimension is the space between the upper and lower jaws. In a normal occlusion with a full dentition the space is ideal with the teeth and jaw working in harmony. Over time, especially in older patients this space can diminish if the natural teeth are worn down from bruxism or lost due to decay or periodontal disease.
This loss of vertical dimension or bite collapse can result in damage to the jaw joints, severe pain or dysfunction in the jaw joints, frequent muscle tension headaches, tooth fractures and tooth loss, and aggravation of periodontal disease if present. Other resulting issues are shortening of the lower face height, 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.
Dr. Howard Kopel speaks on the loss of vertical dimension as relating to adult aging and provides examples such as shorter facial proportion, crack at corner of lip, etc. as well as how to restore the patient back to a youthful appearance.