Can I file a utility patent if my provisional patent has expired?

I would highly recommend that you consult with a registered patent attorney as soon as possible. The time periods described below represent only a few of the factors that will influence how quickly a patent application should be filed. Under U.S. patent law, a patent will not be granted to an applicant unless the application is filed less than one year from the date that the invention was sold or offered for sale within the United States. Yet another condition imposed under U.S. patent law is that the patent will be denied unless the application is filed within one year of the date the invention was described in a printed publication anywhere in the world. If either of the above events, occurring more than a year ago, it will be a complete bar to the patentability of your invention. Thus, if your invention has been described in a printed publication anywhere in the world, or if your invention has been sold or offered for sale in the United States, then you would be wise to pay close attention to the dates on which those events occurred, and to make sure that you consult competent counsel long before the expiration of the one year grace periods. While these are the two most commonly mentioned "statutory bars" to patent registration under U.S. patent law, they are by no means the only factors that should be taken into account when one decides when to file a patent application or to consult patent with a registered patent attorney. Numerous other factors influence the timing of the filing of a U.S. patent application. For one thing, there is always the possibility that someone else has filed or will soon be filing a patent application on the same subject matter. The sooner you file, the more likely it is that you will prevail against someone else who has filed or is about to file. The discussion up to this point assumes nothing more than that the inventor is interested in getting United States patent protection. It is important to keep in mind, however, that if there is any possibility that the inventor would want to seek patent protection in countries outside the United States, then it is imperative to seek advice of competent counsel in advance of any public disclosure or sale of the invention. The reason for this is that in many countries outside the United States, public divulgation of the invention at any time prior to the patent application may bar the grant of the patent. For the above reasons, it is always wise to try to get a patent application on file prior to any public disclosure or sale. Even if the invention has not been publicly divulged there are reasons to file a patent application sooner rather than later. Filing the application sooner will help to some extent in prevailing over others who happen to have developed the invention independently and who also file a patent application. In the United States two approaches are possible to the protection of an invention in the face of a statutory bar such as the on-sale bar or the publication bar: the filing a patent application or the filing of a provisional patent application.