The aim of this study was to determine the prevalence of idiopathic osteosclerosis (IO) and condensing osteitis (CO) in Zagreb patient population sample according to age and sex, localization in the jaw, as well as dental relationship between IO and CO lesions. A retrospective study was performed using orthopantomograms of 1200 patients who underwent dental treatment. Descriptive characteristics of radiopacities, including the size and information concerning the tooth involved, were recorded and processed using chi2-test. A total of 114 radiopacities were identified, 34 IO in 29 subjects (16 female and 13 male, mean age 35), and 80 CO in 69 subjects (38 female and 31 male, mean age 37). There were no significant sex differences. Both CO and IO showed greater predilection for occurrence in the premolar to molar region of the mandible. Our results indicated a low prevalence of IO and CO in the population of Zagreb. Our findings support the theory that IO lesions should be considered developmental variants of normal bone architecture unrelated to local stimuli, whereas CO lesions could be considered reactive formations related to teeth with deep caries, large restoration, or pulpitis.