R.I. Gen. Laws § 28-33-9

When an injury results in no incapacity or incapacity of three (3) days or less and a dispute arises between the employee and the employer or insurer as to the payment of medical expenses or other services provided under §§ 28-33-5, 28-33-7 and 28-33-8, the employee or the medical provider may file a petition with the workers’ compensation court, which petition shall follow the procedure as outlined in chapter 35 of this title. In no event shall a petition be filed until twenty-one (21) days have elapsed since written demand for payment for the expense or service has been made on the employer or insurer.