Answered by Shaykh Faraz Rabbani
“..it is permitted to use fillings (though not of gold according to the Imam) when there is need for them.”

In the Name of Allah, Most Merciful and Compassionate. May His abundant blessing and most perfect of peace be on His Beloved Prophet, the best of creation, and his family, companions and followers.
Walaikum assalam wa rahmatullah,
It would be sinful to get tooth fillings merely for fashion or adornment without need. However, because of the hardship of removing such fillings it would be excused and the subsequent purificatory baths and prayers would be valid. See attached answer(s).
It would be best, however, to remove such unnecessary fillings when it is possible without undue hardship.
And Allah knows best.
Wassalam,
Can I lead others? I have tattoos on my body