Recently, frequency-domain (FD) -optical-coherence-tomography (OCT) methods have been investigated extensively as more efficient and sensitive system compared with conventional time-domain (TD) -OCT. Superstructure-grating-distributed-Bragg-reflector (SSG-DBR) lasers are particularly suited for optical-frequency-domain-reflectometry (OFDR) -OCT with its wide wavelength tunability and frequency agility. We have made a discrete frequency OFDR-OCT system with an SSG-DBR laser, which can tune the wavelength from 1533 to 1574 nm with tuning speed of 10μs per 0.1 nm step. The theoretical expression of the discrete frequency OFDR-OCT is given. Utilizing near-transparent nature of enamel of teeth in the wavelength region of the SSG-DBR laser and long object range of the OFDR-OCT, we have carried out OCT measurements on teeth. Experimental OCT imaging of a canine are reported here.