My friend has a tooth missing and needs dental work on it but needs some grafting which means they have to use cow bone to build the bone. Can you use this in islam or not?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

There is no harm in using the bones of edible animals that have been slaughtered in accordance with the Islamic Sharee'ah for permissible purposes.

However, if the used bones are of dead animals (not slaughtered according Sharee'ah ), the scholars hold different opinions regarding the permissibility of availing oneself of them. The preponderant opinion is that it is permissible just like it is lawful for a Muslim to avail himself of the tanned skin of a dead animal. The Hanafi scholars, as well as Ibn Wahb from the Maaliki school of Fiqh, and Ahmad in one of his opinions in this regard, maintained that the bones of the dead animals are (ritually) pure and that it is permissible to avail oneself of them. This is the opinion adopted by Shaykhul-Islam Ibn Taymiyyah . This is because these bones are a usable substance and not susceptible to rot and decay. Accordingly, they are ruled as ritually pure like tanned skins. In addition, the dead animals are not inherently impure; but they are impure due to the flowing blood and impure liquids that they contain. These (impure) substances and liquids, however, are not found in bones.

Allaah Knows best.