Assuming you are from Illinois, like myself, you probably have a moderate chance of getting accepted at either state school. This should not discourage you from applying. I definately think that you will get accpeted somewhere (nova, NYU, indiana, Marq) this year, but don;t hold your breath for UIC or SIU
I am a UIC grad, with same DAT, but higher GPA, it took me 3 tries to get accepted to UIC, I never got accepted to SIU. The best way to look at this is by school.
Overall in talking to admission counselors there are almost 400 Illinois residents applying to dental school every year, trying to get one of the 115 spots (50+65). I have it on good authority that UIC will boost their class up by 10 next year (class of 2007)
SIU_SDM: the better of the 2 state schools. In fact in the last 5 years they have been in the top 4 or 5 in part 1 of the national boards. This school, puts high emphasis on the DAT (as in better then 18), and science GPA (they want at least 3.2). You should have a 3.4 and a 18 DAT to be considered. The major factor that SIU considers is location, as in where you live. The reason this school was started is to get more DDS's (or DMD's) in Southern Illinois. While some people do get accepted from Chicagoland, they try to get the downstaters. If you are from Cook county, you are at a disadvantage.
UIC: an OK school. I think that in the last few years their reputation has been slipping, but with the closing of Loyola and NW, they have stepped up their research and realized that they have to be Chicago's dental school. The new dean has some great ideas, I think that in 5 years UIC will be great, I just couldn;t wait that long. You have a good chance to get accepted here. UIC doesn;t care about the DAT, as long as you get a 14. UIC also loves undergrads from the state schools, especially UIUC. Your GPA is a little, low, don;t expect a Dec 1st acceptance, but don;t be surprised if you get a letter in March. For UIC you don;t have to retake the DAT.
I would apply to several out-of-state privates (nyu, detroit, marquette, creighton, nova, case-west, the bostons, and pennsylvanias), and those that encourage out-of-staters (michigan, indiana, iowa, the kentuckys). Not to mention the new school in Arizona.
Your research and volunteering are normal. Everyone has that, and most people have dental assisted, so those won't set you apart. I hope this helps, feel free to ask more questions.