Sorry to hear that your kitty is having difficulty eating hard kibble. Unfortunately, halitosis (bad breath) and a decreased or picky appetite can be due to a number of underlying medical conditions. As you have pointed out, dental disease is a large cause for concern and can range from broken teeth, tooth root abscess, dental resorptive lesions, infections or inflammatory conditions of the soft tissues of the mouth, etc etc. There are also systemic body conditions that can result in a pet having both bad breath and/or developing a decreased or more picky appetite, such as kidney disease.
The first step in helping you and your kitty will be to have one of our veterinarians look at her. After discussing your concerns more in depth and completing a thorough exam we can discuss what diagnostics and/or treatments may be indicated. I hope this helps. Please let us know if you need further information.
Susan Vaughn, DVM