This is to acknowledge and thank you for your question posted at Avvo.com
By statute, an applicant must be a person of good moral character for 5 years (or for a spouse of a USC, 3 years, or for person in the military, one year) prior to filing and up to the time of admission. The applicant must admit the arrest (but not the criminal act) on the appication and document the dismissal. If you are unclear on the above see an immigration attorney.
Please be advised that my response to your question does not create an attorney-client relationship.
Such a relationship is determined primarily by principles of agency and contract law. The relationship begins when the client acknowledges the lawyer's capacity to act on his or her behalf and the lawyer agrees to act for the benefit and under the control of the client.
You should not have a problem when you apply for citizenship if this is your only criminal matter. Based on your information it appears the charge was dismissed. Even if it had not been dismissed, since it occurred more than five years ago, it still would not have created a problem.
When you file for citizenship you will still have to disclose the arrest and provide court certified copies of the police report, charge, PTI agreement, and final disposition - if available. Because your case was a misdemeanor the Clerk will only keeep the records for five years, so you may only be able to get a one page certification of diposition.
Do not apply to have your record sealed or expunged unil after you become a citizen as doing so could complicate the process.
Even though you will be able to get your citizenship next year,because of the criminal history, I strongly recommend you retain an attorney to help you with the process.
We would be happy to assist you.