Musannaf Ibn Abi Shayba 18:809

Abu Bakr narrated to us, he said: Sahl ibn Yusuf narrated to us, from ‘Amr, from al-Hasan, who said regarding the tooth of a young boy if it has not fallen out: He said: Two just men shall look at it. If it has grown, something shall be assigned for it [as compensation/diyah]. And if it has not grown, it shall be like the tooth of an adult man.