Applying to PhD programs in mathematics: would a letter of recommendation from my department chair at the community college be of any advantage? I finished my MS in mathematics 5 years ago.  Over these years I have been teaching at a community college (primarily calculus 1,2,3 with analytical geometry and Ordinary Diff. Eqs).  When I was in my masters program I was having trouble narrowing my interests and decided to stop at my masters and start teaching. During this time as an instructor I have become very interested in some applied mathematics (biology in particular).  I plan to apply to several PhD programs in the near future.   With that said, I didn't keep in touch with too many people from the university I attended.  I did stay in touch with a couple of my professors (on a minimal basis) and plan to ask them for letters of recommendation.

My questions...

Would a letter of recommendation from my department chair at the community college be of any advantage (and even suffice as 1 of the 3 required)?  Or should I call a professor from 5-7 years ago that may remember the grade they gave me?  To me the latter seems very generic and I feel my department chair could say more about my dedication to mathematics and teaching.

Thanks!
I agree, the letter from your current department is likely to be more meaningful than a letter from someone who barely remembers you. The people reading your file will immediately recognize you as a "non-traditional" applicant (i.e., not straight out of undergrad), and will not be surprised that the letters in your file do not follow the pattern of traditional applicants. 

While many employer letters are utterly dispensable in graduate admissions, it's a different story when the employer is a math department, "even" at a CC. Chances are that some of your target departments (at least those that combine pure and applied math) are struggling to staff their remedial courses. Slightly cynically speaking, they will be happy to have an instructor with faculty-level experience and TA-level salary (in addition to research prospects).