Have you ever seen the real-life version of “dripping water wears away a stone”?

Many people know the idiom "dripping water wears away a stone", but no one seems to have seen such an example in real life. However, there is a kind of dental disease that can be regarded as the real-life version of "dripping water wears away a stone".

As the hardest organ in the human body (no doubt about it), teeth are like small stones, right? However, even if they are as hard as rocks, teeth can be "punctured". This is another common dental disease besides tooth decay, the so-called "wedge-shaped defect".

So, what does a wedge-shaped tooth look like? And what force "punctures" the tooth?

The teeth that were "punctured"

Among the common oral diseases, in addition to tooth decay, there is another type of tooth with a very distinctive appearance, that is, a gap appears on the neck of the tooth on the labial and buccal sides, and the gap is a wedge-shaped, shallow dish-shaped or a defect in between. This type of tooth gives people the feeling that the tooth has been pierced by some invisible force, and the crown may even look shaky.

Image source: Reference [1]

Even a sharp weapon has its weaknesses

As a weapon that dares to fight against all kinds of food, the strength of teeth is unquestionable. However, this does not mean that teeth are invulnerable.

From the general structure of teeth, the crown, which is directly in contact with food, is the strongest part of the tooth because it has thick enamel as armor; the root is not as indestructible as the crown, but it is still covered with a thin layer of cementum, which is also acceptable; while the neck of the tooth is either only covered with thin enamel and cementum, or completely unprotected. Therefore, the neck of the tooth can be regarded as the soft rib of the tooth, and thus it has become the source of many dental problems. Wedge-shaped defects are one of them.

Where does the invisible force come from?

Undoubtedly, the occurrence of wedge-shaped defects is related to the fragility of the tooth neck structure. However, external factors cannot be ignored.

There is an "abfraction" theory about the mechanism of wedge-shaped defects. Abfraction means "detachment" and comes from the Latin "ab" and "fractio". This theory holds that occlusal pressure and tensile stress cause the tooth structure in the cervical area to bend, leading to microfractures of the hydroxyapatite crystals in the enamel and dentin, resulting in fatigue and deformation of the tooth structure. However, this theory has not yet been conclusively confirmed.

Image source: Reference [2]

The mainstream view is that wedge-shaped defects are caused by multiple factors. These factors include chemical, biological and behavioral factors, such as the effect of acid and improper brushing methods. It goes without saying that the bristles of a toothbrush are not as hard as the teeth, but they can "break" teeth with a brush, which is indeed like "dripping water wears away stone".

What are the consequences of a wedge-shaped defect?

The impact of wedge-shaped defects on teeth can be significant or minor. Some defects do not cause any other symptoms except for changes in appearance, but some may cause tooth sensitivity, pulpitis, etc., so they need to be treated appropriately.

Because the defect is located in a special area, it may not be easy to repair this type of tooth disease, or the repair effect may not be ideal. Based on this, it is more important to prevent wedge-shaped defects from occurring.

References

[1] Sarode GS,Sarode SC. Abfraction: A review[J]. J Oral Maxillofac Pathol, 2013, 17(2): 222-227.

[2] Lee WC, EakleWS. Stress-induced cervical lesions: review of advances in the past 10 years[J].J Prosthet Dent, 1996, 75(5): 487-494

[3] Nascimento MM, Dilbone DA, Pereira PN, et al. Abfraction lesions: etiology, diagnosis, and treatment options[J]. Clin Cosmet Investig Dent, 2016,8: 79-87.