Even if your case was "DISMISSED" in criminal court, it is very common that the dismissal was obtained after pleading "guilty" or "no contest/nolo contendre" and completing some form of probation or community service. If so, then it will be considered a conviction for immigration purposes even though you may have a "CLEAN RECORD" under state law. Getting a case dismissed could still make you deportable/removable from the U.S. If you are a legal permanent resident, you need to have all of your criminal cases reviewed to make sure you are not deportable or removable, and properly prepared for your naturalization process. The law has changed recently and what may not have been a problem before could now result in you being placed in deportation/removal proceedings. REMEMBER to tell your attorney about each and every arrest and/or criminal matter you have ever been involved in anywhere in the world.
Case Dismissed? Great, But You Can Be Deported. Criminal Cases Affect the Naturalization Process