All posts by Dr. Glenn Clark

Dr. Glenn Clark

About Dr. Glenn Clark

Dr. Glenn Clark, DDS is an expert on sleep apnea, orofacial pain and oral medicine, and Temporomandibular Joint Disorder (TMJ). Dr. Clark serves as the Director for the Advanced Program in Orofacial Pain and Oral Medicine at the Herman Ostrow School of Dentistry of USC.

Picture of tooth erosion from dental abfraction. USC postgraduate dental program.

Dental Erosion from Abrasion & Abfraction

What is dental abrasion?

Dental abrasion 20100113 005

Unlike dental attrition, abrasion is the loss of tooth structure by mechanical forces from a foreign element. If this force begins at the cementoenamel junction, then the progression of tooth loss can be rapid since enamel is thin in this region of the tooth. Once past the enamel, abrasion quickly destroys the softer dentin and cementum structures.

The appearance is commonly described as V-shaped when caused by excessive pressure during tooth brushing. The teeth most commonly affected are premolars and canines. Abrasion usually shows as worn, shiny, often yellow/brown areas at the cervical margin.

Abrasion is the wearing away of tooth surface caused by friction or a mechanical process. Abrasion happens when teeth are brushed too vigorously in sweeping horizontal strokes. The use of a hard toothbrush can also cause the problem.

It is often evident on the outer surfaces of the back teeth. A wedge or V-shaped indentation of the tooth will be seen at the gum margin. Toothbrush abrasion can be repaired by bonding a tooth-colored filling over the abraded area of the tooth.

Dental Abrasion Causes

Sources of tooth erosion from dental abrasion include:

  1. Vigorous horizontal tooth brushing
  2. Nail biting, pen biting, and pipe smoking
  3. Denture clasps
  4. Abrasive dentifrices
  5. Hard toothbrushes

What is dental abfraction?

Picture of tooth erosion from dental abfraction. USC postgraduate dental program.

Abfraction is the loss of tooth structure from flexural forces. This has not been supported by dental research, but it is hypothesized that enamel, especially at the cementoenamel junction (CEJ), undergo this pattern of destruction by separating the enamel rods.

As teeth flex under pressure, the arrangement of teeth touching each other, known as occlusion, causes tension on one side of the tooth and compression on the other side of the tooth. This is believed to cause V-shaped depressions on the side under tension and C-shaped depressions on the side under compression.

This theory does not fully satisfy many researchers because there are many teeth whose occlusion causes tension and compression on either side. Consequently, it would be expected that many more teeth would show signs of abfraction, but this is not the case. Research is ongoing to identify the role abfraction has on this pattern of tooth destruction.

What are the causes of abfraction?

Occlusal forces are blamed as they might cause the tooth to flex, causing small enamel flecks to break off, inducing the abrasive lesions. Usually, there are wedge-shaped lesions with sharp angles found at the cervical margins.

What has recent literature suggested about whether abfraction is real or not?

Bartlett DW, et al.’s critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear.

Stress Analyses in the Theory of Abfraction

A report by Litonjua LA et al. examines studies on mechanical properties of enamel and dentin and studies on bite forces and chewing.

Through their research, they found that abfraction is entirely based on FEM studies, and recent dental stress analyses have been contradictory. Newer studies include PDL and alveolar bone in the models, and new models show that occlusal forces dissipate and are not concentrated at the cervical region.

In conclusion, the key basis of the abfraction theory may be flawed.

Postgraduate Dental Specialty Degrees

Dr. Glenn Glark, DDS, MS prepared this for his Geriatric Dentistry course on Systems Physiology, Motor Disorders and Sleep Apnea. Are you interested in earning a dental specialization? Learn more about our online dental specialty programs today.

A Picture of Dental Attrition of the Teeth

What is dental attrition?

What is dental attrition?

Typical Appearance of Dental Attrition of the Teeth

The definition of dental attrition is the mechanical wearing of the incisal or occlusal surfaces of teeth as a direct result of functional or parafunctional tooth-to-tooth contact. The process is usually slow and rarely results in pulpal disease as secondary dentine is laid down to protect the pulp. Tooth pain is rarely associated with attrition, and men typically show a greater degree of attrition than women. Most attrition occurs during sleep, and its rate is faster in patients with inadequate salivary lubrication of the teeth.

Are there different types of attrition of teeth?

Normal attrition is slow tooth wear associated with chewing, and there is faster dental wear related to sleep disorders like sleep bruxism. Sleep Bruxism causes dental attrition from the lateral motion of the teeth. We also find tooth-to-tooth wear when natural teeth are opposing porcelain crowns.

Sleep Bruxism & Dental Attrition

There have been several articles on this topic. Baba K, Haketa T, Ohyama T, and I sought to answer the question, “does tooth wear status predict ongoing sleep bruxism in 30- year-old Japanese subjects?

In our study comparing tooth wear and bruxism levels, we observed 16 subjects (8 bruxers & 8 age- and gender-controls) with a mean age of 30 years. We used Murphy’s method to form dental casts and measured bruxism level with EMG recordings for five nights.

We found Murphy’s scores and duration of bruxism levels were not correlated. In conclusion, tooth wear status is not predictive of ongoing bruxism level in 30-year-old Japanese subjects.

Why do some bruxers have tooth wear and some do not?

Lubrication is critical to the rate of wear. Johansson A, Kiliaridis S, Haraldson T, Omar R, Carlsson GE in their study, “Covariation of some factors associated with occlusal tooth wear in a selected high-wear sample,” investigated co-factors associated with occlusal tooth wear by studying 59 subjects with a mean age of 35 years, ranging from 16 to 70-year-olds. All subjects had a full or nearly full complement of natural teeth, and all had the presence of definite clinical signs of occlusal wear.


  1. Men > women on wear of the teeth
  2. Greater age = greater wear
  3. Greater bite force = greater wear
  4. Decreased occlusal tactile sensitivity = greater wear
  5. Increased endurance time = greater wear
  6. Low buffer capacity and low rate of secretion = greater wear

In conclusion, the greater the force and inadequate lubrication produces more attrition!

Age Appropriate Attrition

Age% LifeMax Expectmm

How is the severity of attrition scored?

  • #0 = no wear at all
  • #1 = small enamel wear (physiologic)
  • #2 = large enamel wear (accelerated but no dentin exposed)
  • #3 = large enamel & dentin exposed (<1/3 of crown).
  • #4 = > 1/3 of crown lost

Dentist’s should also describe the region: Maxillary; Mandibular; Anterior; Posterior, or Generalized.

Is Bruxism strong enough to damage other tissue beyond the teeth?

Yes, we think Bruxism can stretch the TMJ tissues causing disk displacement.

Correlating TMJ Signs & Symptoms with Bruxism Level

In our article, Association between masseter muscle activity levels recorded during sleep and signs and symptoms of temporomandibular disorders in healthy young adults, we studied 103 healthy adult subjects (age 22-32 yrs). Each subject filled out questionnaires and were examined. Each subject had six consecutive nightly masseter EMGs.

We found that gender was significantly related to the duration of EMG, and that joint sound scores were significantly associated with the duration of the EMG activity. In conclusion, the results suggest that both gender and clicking are significantly related to
duration of the masseter EMG activity during sleep.

Postgraduate Dental Programs

This content was originally prepared by Dr. Glenn Glark, DDS, MS as part of course, “Systems Physiology, Motor Disorders and Sleep Apnea for Dental Residents.” Are you interested in earning a dental specialization like Geriatric Dentistry? Check out our program page for more details on the course curriculum and admission process. staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. [CC BY 3.0 (]

What is Tooth Erosion? Causes, Diagnosis, and Treatment

What is tooth erosion?

Erosion is the wearing away of the tooth surface by an acid, which dissolves the enamel and the dentine. There are a variety of ways that tooth structure is lost.

Food-based dental erosion was first described in 1892 among Sicilian lemon pickers. Food and beverages can dissolve tooth structure if they are acidic enough. Gastric regurgitation is another source of acid that can dissolve teeth. Exposure to environmental substances in the air might also be a source of the erosive chemical. While rare, some individuals have saliva that is acidic enough to dissolve exposed dentin surface, and when it is impossible to find the source, this is called idiopathic erosion.

Six Dental Erosion Causes

  1. Dietary
  2. Regurgitation
  3. Environmental
  4. Flow of saliva
  5. Exposed dentin
  6. Idiopathic

Food & Beverage Causes of Tooth Erosion

Two sources of acid in the mouth are dietary and gastric, and the acid dissolves the calcium in the tooth. Beverages with high acid content include all carbonated beverages and citrus-based drinks (orange juice, grapefruit juice). Additionally, wine has been shown to erode teeth, with the pH of wine as low as 3.0–3.8.

De-mineralization that Occurs in Acidic Mouth

The degree of tooth erosion from acidic beverages is directly related to the frequency and amount of these beverages that are consumed. Foods that are high in acidic content include citrus fruits (oranges, lemons, and grapefruit) as well as pickles and vinegar. Frequently consumed foods and drinks with a pH below 5.7 may initiate dental erosion.

Sources of Dietary Tooth Erosion

  • Citric acid in soft drinks
  • Acidic fruit juices
  • Acidic sugar-free drinks
  • Fruits

Tooth Erosion from Regurgitation

Blausen 0863 ToothAnatomy 02

The acid produced in the stomach during the digestive process is sufficiently powerful to dissolve any food, including bone and teeth. When the contents of the stomach are regurgitated, the acid comes into contact with the teeth. Any condition that causes repetitive vomiting or regurgitation will cause erosion of teeth.

The dentist is often the first to notice the problem. The back surfaces of the front teeth are the first to be affected. The erosion is seen as a light yellow patch on the tooth. This indicates that the enamel has been dissolved and the sensitive dentine under the enamel has been exposed. This exposure of the dentine will result in pain from sweet, hot, and cold food and drinks. If the erosion penetrates deeper and reaches the nerves and blood vessels, the pain can become severe.

People with diseases such as gastroesophageal reflux disease (GERD)1, anorexia nervosa, and eating disorders like bulimia suffer from tooth erosion. GERD is quite common, and an average of 7% of adults experience reflux daily. The leading cause of GERD is increased acid production by the stomach.


Sources Tooth Erosion from Regurgitation

  1. Eating disorders
  2. Gastrointestinal (GERD)
  3. Chronic alcoholism

Erosion from habitual regurgitation of gastric contents can be increased with a heavily acidic diet. Regurgitation produces wide shallow lesions, enamel may be completely lost, and the patient might not admit to an unattractive aspect of psychological illness.

Role of Saliva in Tooth Erosion

Saliva acts as a buffer to dental erosion, lowering the pH when acidic drinks and food are ingested. Acidic foods and beverages will have a greater effect on patients with hyposalivation due to primary xerostomia, drug-related hyposalivation, Sjogren syndrome-related hyposalivation, and radiotherapy gland damage with secondary hyposalivation.

In some individuals, saliva itself may be the cause of the erosion. In some individuals, salivary pH is lower because of medications taken that alter saliva such as vitamin C, aspirin, and some iron preparations. Mostly saliva is not acidic enough to dissolve enamel, but exposed dentin is another story. When dentin is exposed due to attrition or abrasion, dentin dissolves at pH 6.0 (remember pH 7.0 is neutral). Patients with dentin that is dissolving will typically show cupping erosion on the occlusal surfaces of the teeth.

Environmental Causes of Dental Corrosion

Possible sources of erosive acids are from exposure to chlorinated swimming pool water. Erosion has been seen in battery plant workers, picklers and miners who are around the fumes which are acidic.

What is idiopathic tooth erosion?

Idiopathic erosion is by definition, when you do not know the cause.

How to Diagnose Tooth Erosion

Dental erosion (hypoestrogenia) no211

The process of diagnosis involves a series of questions:

  1. Is it really erosion and if so, what type?
  2. Does the patient report or exhibit signs of regurgitation?
  3. Does the patient report or exhibit signs of reflux?
  4. Does the patient report ingestion of acidic foods or drinks?
  5. If it is erosion, is it current or is it old?
  6. How severe and progressive is it?
  7. Does it need monitoring or treatment?

What is the best way to monitor dental erosion?

The best way to monitor tooth erosion is by documenting the current state of the problem with photos or models, and periodically recalling and comparing these photos or models.

Tooth Erosion Treatment & Repair

The answer depends on the type of dental erosion. Below are some options for treatment of active tooth tissue loss.

  1. Treating the underlying medical disorder or disease.
  2. Modifying the pH of the food or beverage contributing to the problem
  3. Changing the patient’s lifestyle to avoid the food or beverage.
  4. Decreasing abrasive forces.
    1. Use a soft-bristled toothbrush and brush gently.
    2. Leave at least half an hour before brushing teeth after consuming acidic food and drinks (teeth will be softened)
    3. Rinse with water after consuming acidic foods and drinks.
  5. Drinking through a straw.
  6. Using a re-mineralizing agent, such as sodium fluoride solution in the form of a fluoride mouth rinse, tablet, or lozenge, immediately before brushing teeth.
  7. Applying fluoride gels or varnishes to the teeth.
  8. Drinking milk or using other dairy products.
  9. Using a neutralizing agent such as antacid tablets.
  10. Applying dentine bonding agents to areas of exposed dentin.

Severe Tooth Erosion Repair

Gold and porcelain are logical, and below is an abstract that describes treating severe dental erosion with ultra-thin CAD/CAM composite occlusal veneers and anterior bilaminar veneers.

Ultrathin Bonded Veneers for Tooth Erosion

The study found that ultra-thin occlusal veneers is an alternative erosion treatment, and reported cases of complete mouth rehabilitation with veneers. In this Patients in this study had severely eroded dentition, and the dental clinician took a bilaminar approach to the a maxillary anterior teeth. This method allows only strategic reduction with no preparation.

Prevention of Tooth Erosion

There are a few ways patients can prevent dental erosion. From an oral healthcare point of view, patients can use fluoride toothpaste, mouthwash, gel, or desensitizing toothpaste. For dental erosion from acidic beverages and food, patients can limit acidic food/drink to mealtimes or totally, stop drinking carbonated beverages, do not drink citrus fruits or use a straw.

If caused by regurgitation, eating disorder, or alcohol addiction then refer the patient to a Psychologist. If Gastroesophageal reflux disease (GERD), refer the patient to their physician.