How does a person who underwent mouth or nose surgery perform ablution?
The ruling of mazmaza and istinshaq (taking water into mouth and nose) is contraversial among scholars. This is because whether mouth and nose is included in the face that has to be washed as a required act of ablution. According to the majority including Hanafi, Shafi’i, and Maliki schools, taking water into mouth and nose is one of the sunnah acts of ablution (Marghinani, al-Hidayah, I, 16; Nawawi, al-Majmu’, I, 465; Khattab, Mawahib, I, 245). Hanbali school says that taking water into mouth and nose is fardh in both ghusl and ablution (Ibn Qudamah, al-Mughni, I, 88).
In this matter, the proofs of the majority is stronger and more accurate. Accordingly, as it is sunnah to wash mouth and nose in ablution, that a person do not perform these during ablution due to a disease or surgery or without any reason does not affect validity of the ablution.
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS