Dendrobium repotting and root rot?

[Cruzzfish]

I was repotting Den. nobile gold star and a few others today because they were in a really bad media and I saw some black roots. Should I cut these off to stop it from spreading or will it make it open to infection?

http://i.imgur.com/VAzez0p.jpg

 

[DragonsEye]

Doesnt look like it should be a big issue either way. Considering the number of roots present, removal of that one suspect root will not pose a problem. Use a sterile razor blade and cut well above the blackened area. Dust the cut with cinnamon. Pot up the plant but do not water for a rew days.