Grinding, Clenching and Tooth Wear
If you grind your teeth at night or clench your jaw, you may be one of millions of people who suffer from bruxism. And the worst part is you probably will not even know it until you start experiencing the myriad of painful issues from tooth fractures to changes in facial appearance caused by the chronic bruxism. This blog post will discuss tooth wear and focus on mechanical wear caused by bruxism, its symptoms, consequences and treatment options.
What is Tooth Wear?
Tooth wear is loss of tooth structure due mechanical or chemical injury to the tooth. Unlike decay, which is caused by microorganisms, tooth wear is related to repeated microtrauma to the tooth structure over an extended period of time.
The enamel is the outer layer of the tooth and the hardest substance in the body, ranking 5 on Mohs hardness scale, harder than gold, silver iron and steel. The large amount of mineral in enamel accounts not only for its strength but also for its brittleness. When wear penetrates through the enamel, it exposes the inner tooth structure (the dentin) and increases seven times faster due to the softness of the dentin. This exposure renders the softer dentin more susceptible for developing decay as well.
Tooth wear is usually symptom free and can progress without patient’s awareness. Prevention of tooth wear is paramount, as moderate and advanced wear cases are increasingly extensive and costly to correct.
What Causes Tooth Wear?
Tooth wear can be caused by mechanical or chemical factors:
- Mechanical tooth wear comes from empty mouth tooth bruxing which causes attrition of the tooth surfaces that are repeatedly rubbing against each other; or it can be caused by foreign objects, such as a toothbrush abrasion, nail biting habit, bobby pins, sunflower seeds etc.
- Chemical tooth wear or erosion is due to constant exposure of the tooth to an acidic environment, and this happens in patients with acid reflux, or GERD, bulimia, frequent vomiting due to pregnancies or disease. Acid erosion on teeth can also occur with overconsumption of acidic foods such as carbonated drinks, citrus fruit, chewable vitamin C tablets, aspirin and other acidic foods and drugs. Any food or liquid with a pH of less than5.5 can demineralize teeth.
What is Bruxism?
Bruxism is an involuntary and subconscious oral habit consisting of rhythmic gnashing, grinding or clenching of teeth. Because these movements are not part of the chewing cycle of the jaw, they are considered parafunctional and detrimental.
There are two types of bruxism: static and dynamic. In addition, if you have bruxism, you may be clenching and grinding your teeth at night (sleep bruxism), during the day (awake bruxism) or both.
Causes, Symptoms and Consequences of Excessive Teeth Grinding
Static bruxing is called clenching. Here the masticatory (chewing) muscles exert forces on the teeth when they are closed together, without moving the jaw. Craze lines, cracks, and chips may be present on the teeth or dental restorations, but wear facets are usually absent. Strong clenching of teeth can be a normal manifestation of increased muscle tonus associated with emotional stress, or physical activity, such as heavy lifting.
Dynamic bruxing is known as grinding. The teeth surfaces rub against each other uncontrollably causing attritional wear facets of those contact surfaces. These facets are flat and shiny, and appear exclusively on the chewing tooth surfaces. On the contrary, an acid erosion wear on the tooth can appear on a chewing or a non-chewing surface of the tooth, has a round shape like a well, and is deeper in the middle of the lesion.
Why Do I Grind My Teeth?
The etiology of bruxism is not completely understood and may be different for daytime vs nighttime bruxing and grinding vs clenching.
Stress, personality type, diet, habits, age, and genetics all play a role in bruxing. Some medication, such as certain antidepressants can increase the frequency of clenching and grinding. Bruxing is also commonly associated with airway disturbances such as sleep apnea and medical conditions that produce excessive stomach acid, such as GERD.
Successful elimination of clenching is not as predictable as grinding. In either case, preventive measures go a long way in controlling the extent of tooth wear, and preventing it from becoming more complex and costly to treat.
What are Signs and Symptoms of Bruxing Besides Tooth Wear?
Besides tooth wear, signs and symptoms of bruxism may also include:
- craze lines (crack lines) on the teeth - these are small, hairline fractures, usually on the back teeth, and commonly associated with an amalgam fillings;
- chipped, cracked or broken teeth or restorations, such as veneers or crowns;
- cervical abfractions - these are small notched areas on the neck of the tooth, along the gumline, where tooth structure is missing;
- tooth mobility;
- overly sensitive teeth;
- supraeruption of teeth - teeth that have shifted position to compensate for the wear;
- scalloped tongue - when clenching, the tongue braces against the teeth and over time its outer outline has their imprints making it look scalloped;
- clicking or popping in the jaw joint;
- limited mouth opening;
- deviation of the lower jaw when the mouth opens;
- jaw locking;
- hypertrophic and or tender chewing muscles, especially in the morning;
- facial pain;
- ringing in the ears;
- frequent headaches;
Craze Lines Due to Bruxism
Example of craze lines due to bruxism
Dental Cervical Abfraction Due to Bruxism
Example of Cervical Abfraction Due to Bruxism
Consequences of Tooth Wear
Excessive tooth wear leads to loss of tooth structure and shortening of the teeth, jagged, and sharp incisal edges, unattractive and irregular tooth levels, and change is the smile appearance.
If not treated, the teeth become shorter and shift vertically to occupy the space created between the upper and lower teeth. This phenomenon is called compensatory eruption or supraeruption and enables the teeth to make up for the lost tooth structure at the incisal edge in order to maintain functional bite.
How Grinding And Wear Affect Teeth Appearance, Position and Function
Treatment Options for Tooth Wear Caused by Bruxism
There are preventive and corrective measures to treat tooth wear due to bruxing.
The preventive measures entail occlusal appliance therapy such as splints or mouthguards, teeth alignment and bite correction, stress management, muscle relaxants and dental Botox therapy, treatment of underlying conditions, including sleep apnea, GERD, and medication change.
The corrective measures include orthodontics to reposition the teeth that have supraerupted, and then crowns or veneers to restore the worn teeth to their original size. Frequently when restorations are done on worn teeth, some level of bite change is anticipated and the restorations need to be done simultaneously vs one at a time. This makes treatment of moderate and severe wear very lengthy, expensive and complex.
Treatment of tooth wear due to acid erosion, involves acid control and an occlusal appliance. When the teeth are "bathed" in acid, due to constant exposure to it, the enamel and dentin get demineralized and become softer. Due to the weaker tooth structure, grinding in the presence of acid, happens much faster and can be more extensive. Wearing a guard, to eliminate the mechanical component of wear, slows down the process of wear.