Our tickets are submitted by customers on the customer portal most of the time, then investigated by a front line support employee (which may involve more input from the customer) and if required passed to a developer with details on how to replicate the issue using the comments box. The developer then fixes the issue and updates the ticket with comments (not visible on the portal). The front line support then replies to the ticket so the customer has been updated with the fix. 

The problem is that a customer can add comments as well as replies to their tickets via the portal. When our front line support team look at the ticket list view, there is no way of knowing which tickets are still unanswered (i.e. either a new comment from the customer or developer). We can only filter on last modified which doesn't include comments??

Does anyone know how we would set the system up so we can see which tickets have unanswered comments or replies? Or is there a better way?

Help much appreciated!!