Dents in Nails- Fingernails, Nail Bed, Thumbnails Causes, Meaning & Treatment

Well, it is a known fact that there are certain nail changes that refer specifically to various disorders that could be dermatological or systemic. This prompts the examination of the nails regularly to ensure that notice of any changes in color, surface and shape of the nails are reported and corrected if possible before it functional incapacitation. Information in this material is meant to address dents in nails as a looming nail pathology.

Dents in Nails Meaning, Horizontal, Small & Pictures

General meaning of dents in nails

You probably only view nails from an aesthetic perspective but these structures are really specialized structures that have more than just that to its functions.

They in addition, aid in the increase in sensory perception in the pulp. They also come in handy in the ability of one to pick objects in a fine manner.

Fingernails and Toenails-dents-pitting
Fingernails and Toenails

The nails, just like your tongue could act as a window to your systemic functions and abnormalities.

‘Dents’ is non-specific and may refer to pitting or the formation of ridges. The term however denotes that the pathology referred to herein occurs on the surface of the nail and not under the nail, on the nail bed. Medically, this abnormality is commonly, the beau’s lines which are deep groves that run across the nail surface in a band-like fashion.

It basically extends across the paronychium which is the soft tissue lateral to the nail plate. While its pathophysiology may not be very vivid, it is thought to be caused by a halt in the growth of nail in the germinal matrix below the skin fold proximal to the nail plate, the eponychium.

Beau’s lines could occur as a result of nutritional deficiencies, trauma to the eponychium and systemic infections including pneumonia, mumps and syphilis or conditions with endocrinological basis such as hypothyroidism. As in most diseases, idiopathic or that arising from an unknown etiology and genetic predisposition is probable.

Onychochizia, caused by genetic conditions such as polycythemia Vera and chondrodysplasia punctate leads to formation of dents that run horizontally towards the tip of the nail (Baran R et al, 2005)[1]. Beau’s lines progress with increase in depth within 2 weeks of inhibited nail growth and leads to onychomadesis.

Beau’s lines are themselves triggers to complications such as:

  1. Onychomadesis: an idiopathic freeze of growth of the nail due to dysfunction of the nail matrix that leads to shedding. Unlike onycholysis, this condition leads to shedding beginning from the proximal part of the nail plate, below which you find the germinal matrix.
  2. Onychochizia: horizontal splitting towards the tip of the nail.
  3. Trachyonychia: commonly known as nail pitting resulting from a defect in the deposition of keratin in the germinal matrix due to excess of parakeratotic cells[2].

Various online platforms fail to distinguish various terms that could wrongfully be used to refer to ridges or pits on the nails. Here are some of them:

Muehrcke’s lines

These are vertical lines that occur as a normal process of aging in which case they are harmless. Also known as leukonychia striae, they are surface manifestations of nail bed pathologies.

They result in lines that resemble ridges but which are non-palpable indicating metabolic diseases, hypoalbuminuria (patients albumin <2 g/dL) with end stage renal disease or chemotherapy use. According to Gregoriou S et al, 2008[3], it could also occur in glomerulonephritis and liver disease.

Mee’s lines

These are white ridges that resemble beau’s lines but non-continuous. Also known as true leukonychia characterised by multiple, white lines that transverse the width of the nail or parallel to the moon white (lunula). Mostly due to arsenic intoxication, cardiac failure, Hodgkin’s disease among others.

Note that the dents or grooves are subtle for months without your noticing until they have grown outwards to make them visible enough. The dents may be accompanied by color changes and there could be an overlap between the complications stated before with beau’s lines.

Specific meaning when they’re


These are beau’s lines and often indicate a serious condition. They are indentations or dents that run across the nail plate from one side to another unlike the longitudinal striae. It normally occurs as an aging sign when the ridges become deeper but may be due to acute kidney disease and in the 20-nail dystrophy.

The latter is basically a condition that results in development of beau’s lines on all the 20 nails and a known sign of conditions such as syphilis, diabetes, hypothyroidism and mumps.

Note that horizontal lines could also be accompanied by color change especially after trauma in which the nail bed or the hyponychium is compromised or in more serious systemic conditions such as endocarditis and melanoma. Though the former is best diagnosed with the presence of ‘splinters’ on the nail bed.


These are dents that run along your nail plate, longitudinally from the distal to the proximal parts. They resemble bands and can also be referred to as longitudinal striations. The occurrence of this is generally due to aging and may be considered harmless.

This is due to the reduced rate of cell turn over by the germinal matrix responsible for the deposition of keratin and subsequent nail formation. However, there are conditions that result in vertical indentations which could harm you.

This life-threatening conditions will manifest as a concurrent coloration and changes in the texture.  Such conditions include trachyonychia in which the nails turn dark and surface rough making the nails brittle (onychoschizia). It can also point out to dystrophy of the nails.

Longitudinal striations or indentations (onychorrhexis) may be due to a minor trauma or systemic connotations including nail-patella syndrome, graft versus host disease, rheumatoid arthritis and collagen vascular diseases. Iron deficiency anemia (IDA) could also be a reason for vertical ridges and may lead to clubbed nails (convex-shaped nails) or koilonychia (spoon shaped/concave) 


Interestingly, the distal limit (tip-wards) of the furrow of the dent may aid in the determination of the onset. Sudden attack of a condition results in a furrow with a less steep gradient than that which attacks chronically or protractedly. Therefore, the grooves appear small.


Likewise, as with small dents, this form when there is chronic or slow progressive underlying condition. The dent grows wider with a steep gradient distally that is appreciably palpable.

In reference to the harmless, sign of ageing type of dents on nails, the older you get, the bigger the dents become. This is well attributed to the further decrease in the rate of nail turnover and growth therefore.


grooves dents in nails pictures
dents on nails

What Causes Dents in Fingernails, Thumbnails & Nail Bed

General causes of the dents


Thyroid hormone has been shown to cause adverse effects on cutaneous tissues the nails and hair of those who are affected. In fact, Hale and Ebling performed a demonstration with rat specimen investigating the effect of T4 on the telogen phase of hair growth. This effect is synonymous to that which occurs with nails. In thyroxin toxic nails in thyrotoxicosis, the nails might undergo physical changes in the shape resulting in a concave contour. This is further complicated by Plummer’s nails consequential of tipward onycholysis.

Vitamin Deficiency

If your body is low in vitamins, then ridges could form. B vitamins are important in cell growth and in fact vitamin B 12 is known for its benefits in nail growth. Ridges form when you have this in low amounts. Vitamin C too. This may be a result of low dietary vitamins or a malabsorption of vitamins.

Iron deficiency

Insufficient iron in circulation could lead to iron-deficiency anemia that is mostly characterised by koilonychia in which case the nail plate curves upwards and forms a spoon shape. Hemochromatosis in which iron is highly absorbed may lead to this too. In this condition, the nails may become brittle and may signify iron deficiency.


Fungal infections could lead to brittle nails and nails with ridges. In fact fungal infections are implicated as causes of nail abnormalities and should therefore be considered and explored (National Health Society).


Nail blemishes could occur as a result of chemotherapy. For instance, breast cancer therapy, according to, may lead to drying, bruising, clubbing and formation of dents. Culprit chemotherapeutic agents include doxorubicin and docetaxel among others.


Calcium is involved in the formation nails and therefore a deficiency in your body could make it brittle and even form dents and ridges.

Particular causes in

Finger nails-thumbnails & other fingers

When dents appear on particular fingers, it could be due to:

  1. Fungal infection on that particular finger
  2. Slow development to 20 finger nails disease
  3. Poor nutrition that is low in vitamins, iron, calcium and zinc
  4. Hypothyroidism also makes the thumb nails dent.

Nail Bed

The nail bed is essential for the growth of the nail and without it the nail becomes non-adherent and can be deformed.

At times the nail bed is intact but avulsed from the germinal matrix. The germinal matrix is responsible for the growth of the nail. Eponychial loss due to trauma, excision or amputation of the tips of fingers may cause this.

Sometimes a cicatricial build up beneath the matrix may make the nail assume the shape of the underlying matrix hence formation of ridges (Ravindra Bharathi and Babu Bajantri)[4].

Dents in Nails after Acrylics

Acrylics lead to dents on finger nails due to improper fixing and/or removal. Anyone knows that if acrylics are not removed appropriately they could completely ravage your nails and make them lose their aesthetic look.

Some people even bite them to pull them off. To remove them soak the nails first, get a soft buffer and then smooth the surface. This, if not done, may lead to ridges and dents on nails.

How to Prevent & get rid of Dented Nails

Good thing is that you can prevent the occurrence of dents and ridges on your nails. You can do the following:

  1. Make sure that you supplement your diet or have enough to supply the recommended daily amounts of vitamins, iron, calcium and zinc.
  2. Treatment of the underlying condition. At times waiting too long to treat an infection could lead to complications. For instance, if you notice that you are itching on your fingers, then it is important that you seek medical attention fast to ensure that any fungal infection is treated.
  3. Manage hypothyroidism. Though there have been cases of not recuperating from dented nails even after taking antithyroid drugs, it is good that you prevent the involvement of more finger nails.
  4. Moisturize your nails to protect your eponychial skin. This will also maintain the integrity of the cuticles which protect your germinal matrix. When your germinal matrix is interfered with, then a deformity could occur.


[1]  Baran R, Dawber RP, Haneke E, Tosti A, Bristow I. Martin Dunitz.3rd ed. 2005. Nail configuration abnormalities. A Text Atlas of Nail Disorders: Techniques in Investigation and Diagnosis; pp. 18–24.

[2] Nail pitting and onycholysis.Jadhav VM, Mahajan PM, Mhaske CB; Indian J Dermatol Venereol Leprol. 2009 Nov-Dec; 75(6):631-3.

[3] Gregoriou S, Argyriou G, Larios G, Rigopoulos D. Nail disorders and systemic disease: What the nails tell us. J FAM Pract. 2008;57:509–14.

[4] Bharathi, R. R., & Bajantri, B. (2011). Nail bed injuries and deformities of nail. Indian journal of plastic surgery: official publication of the Association of Plastic Surgeons of India44(2), 197.

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