One of the scholars of al-Azhar was asked about a man with a tooth cavity: if he were to extract it, he would suffer harm and pain and if he were to leave it, he would also suffer harm and pain from water entering the cavity. The only way to prevent this harm is to have the cavity filled with silver or a similar material, which would prevent water from entering it when performing the ritual bath for major ritual impurity. Is it permissible for him, according to Islamic law, to have the cavity filled, or should he have the tooth extracted?

There is no objection in Islamic law to the man in question having his tooth filled, provided the case is as mentioned in the question. When performing the ritual bath, it is sufficient for him to run water over the outer surface of the affected tooth.

There is no objection in Islamic law to having a tooth cavity filled if there is no other way to avert harm except by having it filled with silver or a similar material in the manner described. It is sufficient to perform the ritual bath by running water over the outer surface of the affected tooth similar to what scholars have stated regarding heel fissures into which medication is applied. Moreover, in the circumstances described, the man is not required to have the tooth extracted, as this would entail undue hardship, and the explicit texts, both scholarly[1] and scriptural, state: “He has chosen you and has not placed upon you in the religion any difficulty” (Quran, 22: 78) and “Allah intends for you ease and does not intend for you hardship” (Quran, 2: 185). The Messenger of Allah (peace and blessings be upon him) also said, “The religion most beloved to Allah is the upright and tolerant religion” (recorded by al-Bukhari).

And Allah Almighty knows best.