Those brown (or even black!) streaks that you see on the surface of your crown is a very big no-no. It means that your bur has been maxed out already and needs to be replaced with a new one. A new bur definitely cuts better and more efficiently while leaving less brown streaks as you go. Since we do not use water when doing the bench tests, it creates more friction on the blades that dulls the blade quicker. Actually, there are ways of prolonging the longevity of your burs:
- When reducing the surface of the tooth, it is unnecessary to apply too much pressure. Since the tooth is naturally soft so light pressure is just enough. The pressure should be as if you are sweeping away the surface.
- Do not stay the bur on one place too long, it will increase the friction thus burning the surface. So when placing depth grooves, the bur still moves across the groove just to relieve the friction a bit.
But in any case, if you see that you can’t effectively reduce the surface anymore, it is better to change your bur. Nothing beats the cutting efficiency of a new bur. That’s why we totally recommend that you must hoard and buy a lot for your practice!