Partial expungements are generally a challenge to secure. From my experience, the courts will not consider it if the case is still open. The sentence must be served and all costs must be paid. You should retain an experienced criminal defense attorney to represent you.
I agree with Attorney Keller. The case must be closed before filing an expungement petition. Moreover, it is unlikely you will be entitled to an expungement of the dismissed charges. However, you should be afforded a hearing to present a case as to why your non-conviction data should be expunged. The court will balance the Commonwealth's interest in preserving the record against the harm caused to the individual by maintaining the record. You should consult a criminal defense attorney who can fully explain the process.
James D. Doyle, Esquire - 310 N High Street, West Chester, PA 19380 - (610) 431-8910 - This is for general purposes only and does not constitute an attorney-client relationship. Contact an attorney licensed in your State for specific inquiries