The term oral parafunctional habit is used to describe any abnormal behavior or functioning of the oral structures and associated muscles. Behaviors commonly included in this category may include: bruxism, clenching, excessive gum chewing, lip or fingernail biting, or non-nutritive sucking.
Bruxism is defined as the grinding of the teeth, and is usually involuntary, chronic, and occurs during sleep. Often the individual may be unaware they are grinding during their sleep, and the clinician may have to provide patient education regarding clinical signs. Causes of bruxism include increased stress, anxiety, caffeine intake, or presence of sleep disorders. It may also be a side effect of certain antidepressant medications. Bruxism can cause sleep disturbances, headaches, orofacial muscle pain, mild to severe attrition, teeth fractures, and gingival recession (Figure 10).27
Thumb/digit sucking or pacifier use is classified as non-nutritive sucking (Figure 11). Cessation of these behaviors normally occurs naturally, as the infant progresses towards toddler age. However, if these behaviors continue past infancy, there are likely to be negative impacts on the developing orofacial structures. The American Academy of Pediatric Dentistry recommends intervention for non-nutritive sucking behaviors that continue past the age of three.29
The most obvious clinical signs of a sucking habit may be an anterior open bite or posterior crossbite.31 This occurs due to the excessive pressure of the digit or pacifier against the teeth. The severity of resulting malocclusion is likely determined by three factors: intensity, duration, and frequency.32