The differential diagnosis of the osteocondensing lesions (osteomata and exostoses) is till today a topical issue for the experts. In order to test the reliability of the etiopathogenetic theories advanced up to now, the authors carried out a research on samples of tissue coming from surgical interventions for osteomata and exostoses of the maxillofacial region resortied with optical and polarized-light microscopes (OM-PLM). This research meant to analyze the morphological and structural characteristics of newly formed tissues; a considerable attention has been devoted to the difference between primary and secondary bone and to the quality of cementing lines. Thanks to the data resulted from this study, the authors advanced interesting theories about these pathologies either from an etiological and nosological point of view.