Summary of answer:
Praise be to Allah
It was narrated that Ibn Mas‘ood (may Allah be pleased with him) said: May Allah curse the women who do tattoos and those who have tattoos done, those who pluck their facial hair, and those who file their teeth for the purpose of beautification, changing the creation of Allah, may He be exalted. Why should I not curse those whom the Prophet (blessings and peace of Allah be upon him) cursed? Narrated by al-Bukhaari (5931).
What is meant by those who file their teeth is those who do that in order to create gaps between them so that they will appear younger.
The fact that it says “for the purpose of beautification” indicates that what is prohibited is to do that with the aim of looking more beautiful. From this it may be understood that whoever does these things for medical purposes or to conceal a defect, that is permissible and there is nothing wrong with it.
An-Nawawi (may Allah have mercy on him) said:
With regard to the words “those who file their teeth for the purpose of beautification”, what is meant is that they do that with the aim of looking more beautiful, which indicates that what is prohibited is that which is done for the purpose of beautification. But if it is needed for medical reasons, or to treat a defect in the teeth and the like, then there is nothing wrong with it. And Allah knows best.
End quote from Sharh Saheeh Muslim (14/107)
As-Sindi mentioned in his commentary on Sunan an-Nasaa’i that the words “for the purpose of beautification” may be understood as referring to the filing of the teeth only, or the phrase may be understood as referring to all the things mentioned in the hadith, so it includes tattooing and plucking the facial hair.
Shaykh Muhammad ibn ‘Ali ibn Adam al-Ethiopi said:
In my view the second interpretation is more likely to be correct. And Allah knows best. End quote from Dhakheerat al-‘Uqba (38/131).
This is also indicated by the report narrated by Abu Dawood (4170) from Ibn ‘Abbaas, who said: The woman who does hair extensions and the woman for whom that is done, the woman who plucks facial hair and the woman for whom that is done, the woman who does tattoos and the woman for whom that is done when there is no disease (that would justify doing that) are cursed. Narrated by Abu Dawood (4170); its isnaad was classed as hasan by Ibn Hajar in Fath al-Baari (10/376); classed as saheeh by al-Albaani in Saheeh Abi Dawood (4170).
The words “when there is no disease (that would justify doing that)” come after mention of tattooing, therefore al-Qaari said: This refers to tattooing. Al-Mazhar said: If a woman needs tattooing for medical purposes, it is permissible, even if some trace of it remains.
End quote from ‘Awn al-Ma‘bood Sharh ‘ala Sunan Abi Dawood (11/228).
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:
We must understand the difference between that which is done for the purpose of adornment and beautification, and that which is done to remove a defect. The Prophet (blessings and peace of Allah be upon him) gave permission to the Sahaabi whose nose had been cut off to wear a (prosthetic) nose made of gold to correct the defect resulting from the cutting off of his nose. “And he cursed the woman who files teeh and the woman for whom that is done”, which refers to a woman who files her teeth so that there will be gaps between them and the like. But if it so happens that the teeth are not properly aligned, in a manner that spoils the appearance of the teeth, then there is nothing wrong with taking measures to straighten them.
End quote from Fataawa Noor ‘ala ad-Darb (22/2)
Based on that, if the tattoo is for medical purposes or to conceal a defect that is bothering the individual – as in your case – then it is permissible, and is not prohibited.
The scholars of the Standing Committee for Issuing Fatwas were asked:
I am a young woman suffering from vitiligo which has deformed many areas on my body. I used to use some kinds of make-up and creams to conceal the visible areas, because I could not bear people looking at me, because I am very sensitive about this matter and because of what it caused me of intense psychological distress that affected my social life to the extent that I became very withdrawn, even from my family, especially now that I have grown up and reached the age of twenty-two years. Now I have heard some news that has given me back some hope, which is that there is a kind of make-up that conceals the effects of vitiligo in areas that are visible, and it will remain for a long time, as long as several years, then it fades after that and can be reapplied. My question is: is this make-up prohibited and regarded as being like tattooing? Especially since it is said that it is essential to use special equipment to apply it to the skin. May Allah reward you with good.
This procedure comes under the heading of cosmetic treatments… What appears to be the case is that this procedure comes under the heading of permissible cosmetic treatment, because it is not done for the purpose of making oneself appear more beautiful. Rather it is done to restore normal appearance, and it is not a kind of tattooing, because tattooing is not done to remove a defect; rather it is done for the purpose of beautification. The fact that the procedure is done with special equipment does not affect the ruling, so long as that does not cause harm or involve anything else that is haraam. And Allah knows best. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) was asked:
I am a young man, twenty years old, and about to get married. But what is impacting my life is that on my face I have many dark spots or moles, but some of them attract attention, as some people make fun of me, especially children who laugh at me, so how about the adults? For this reason I am quite withdrawn and introspective. Recently I decided to remove two of them – is there anything wrong with doing that? What if I have them removed surgically?
Changing the creation of Allah, may He be glorified and exalted, is of two types: one type that is done for the purpose of beautification, and one type that is done for the purpose of removing a defect. As for that which is done for the purpose of beautification, such as plucking facial hair, tattooing and filing the teeth: plucking facial hair means removing hair from the face, tattooing means injecting coloured dyes, black or green and so on, under the skin, in a decorative pattern, as we see on the hands and faces of some people, and filing the teeth means filing them to create gaps between them or make them appear smaller and the like, for the purpose of beautification.
The apparent meaning of the texts indicates – in fact the texts clearly state – that this is prohibited; indeed it is a major sin, because the Prophet (blessings and peace of Allah be upon him) cursed the one who does these things.
The second type is that which is done for the purpose of removing bothersome things and defects. There is nothing wrong with this; rather the Sunnah indicates that in some cases it may be required, as in the hadith about the Sunnahs of the fitrah, such as clipping the nails, trimming the moustache and circumcision. In fact these are done for the purpose of removing bothersome things that are off-putting to sound human nature. Islam teaches us to do these things by way of removing bothersome things and defects. In fact I would say that there is another type which may be permissible if a person is faced with bothersome things and he wants to remove them, as this questioner mentioned about these spots or moles. There is nothing wrong with removing them, even by surgical means, if it is most likely that this procedure is safe. Hence Islam enjoins us to treat sickness and the like in Islamically acceptable ways, and undoubtedly these physical defects are a kind of illness or sickness. Moreover, even if they are not a kind of sickness that affects the body and saps its strength, they are a psychological sickness because people suffer a great deal because of them, as the brother who asked this question mentioned. Based on that, we say: there is nothing wrong with having a surgical procedure to remove these things, on condition that it is thought most likely to be safe and that it is thought most likely that he will benefit from this procedure.
End quote from Fataawa Noor ‘ala ad-Darb.