OP- I was in a very similar situation and DID get accepted to dental school, so don't give up. Don't ever give up. I rarely comment on threads but reading some of the things other people have said to you are so ignorant and degrading that I felt I had to comment to give you a ray of hope. Getting stressed out about exams during finals week, and cheating on a test because you feel overwhelmed--very hard to explain your reasoning because I'm sure everyone has experienced this at one point or another. Having a very close relative unexpectedly pass away and clinically being diagnosed with depression resulting in ONE poor decision--very explainable and any human being with a heart and soul will more than likely be able to see beyond your poor decision. My personal story was I had ~3.8 GPA going into my junior year of college and over Thanksgiving break (3 weeks before finals), my grandfather whom I was very close with (grew up without my own father because he passed away when I was very young so in a sense, my grandfather filled that role) passed away, and it was heartbreaking. To add to that, my brother had a tumor discovered in his neck, which at the time was believed to be cancerous. And to add to all of that good news, my girlfriend of 4 years abruptly broke up with me and I found out she was a cheating little b****. Obviously, my world came crashing down at the worst possible time for a college student. I couldn't do any work, couldn't study for finals, could barely drag myself out of bed, and was placed on anti-anxiety medication as well as an anti-depressant. I made the mistake of turning in a friend's paper from a previous semester as an "extra credit re-write" in a non-science class, and got caught. I got an honor code violation for my actions, and posted a 3.36 GPA for the semester--by far the worst of my college career. My point is that common, everyday stress from being a college student is vastly different from uncontrollable, life altering circumstances that will never occur again. Definitely explain in your application how your uncle's death impacted you and why it led you to make a poor academic decision. Unless many of you have been in a similar situation, please don't degrade the OP for making a bad decision and tell him/her talking about an uncle's death is a "cop out" or "not taking responsibility".
The reality of this, however, is that MANY schools you apply to will, unfortunately, look at your application, see that you have an honors code violation, and without looking twice at anything else on your application, throw it away. I applied to 10 schools that I thought I had pretty competitive statistics for, got 2 pre-Dec. interviews, 2 post-Dec. interviews, and 2 acceptances.
If you really want to be a dentist, be a dentist. One bad decision you made when you weren't thinking clearly doesn't mean you're a bad person, it doesn't mean you're unethical, and it doesn't mean you won't make a fantastic dentist. If anyone wants to sit on their high horse and act like they've never made a mistake, then let them. Just don't let them tell you what you can/can't achieve.
Just my 2 cents