A dentist or a dental hygienist licensed pursuant to this chapter under a special volunteer license who is a medical practitioner, as defined by § 63-1-201, engaged in practice at a free health clinic shall not be subject to license fees under this chapter. The board of dentistry may issue a special volunteer license, as such license is defined in § 63-1-201, to qualified applicants without fee or charge. Such license shall be for a period of two (2) years and may be renewed on a biennial basis.