Shama-il Tirmidhi Chapter 001, Hadith Number 014 (014).

Ibn Abbas (Radiallahu anhu) says: "The front teeth of Rasulullah (Sallallahu alaihe wasallam) were a bit wide (spread out). They were spaced out and not close together. When Rasulullah (Sallallahu alaihe wasallam) talked, an illumination emitting from his teeth could be seen."

Commentary:
According to the Ulama, it is a well known fact that it was something similar to nur which emitted from his teeth. The opinions of Allaamah Munaawi is that it was something sensory, and not a similarity, which emitted miraculously from between the teeth of Rasulullah (Sallallahu alaihe wasallam).

Everything of his noble features was perfect and beautiful. In the manner that is real and intrinsic beauty had reached its last stage, in the same manner his zaahiri (apparent) beauty had also reached its fullest and proper stage. Allahumma sali 'alaa Sayyidina Muhammadiw wa 'alaa aalihi biqadri husnihi wa jamaalihi.