Abstract： @@ Dental abnormalities associated with specific syndromes and/or severe systemic abnormalities in tooth number, form or size are challenging cases in dentistry, affecting esthetics and function.1 Microdontia is used to term abnormally small teeth that generally the maxillary lateral incisor or third molar is involved. On the other hand, the entire dentition may be affected as well.1 Prevalence of microdontia range from 1.5%-2%.2 The definition of severe hypodontia is four or more lacking teeth.3-5 The prevalence of severe hypodontia was found to be less than 1% of the unselected population.6 In another study hypo-dontia is seen with a higher incidence in the permanent dentition (3.5%-6.5%), compared to that of the primary one (0.1%-0.9%).7 The etiology seems to be inheritance in most cases of hypodontia. However, some are caused by mechanical trauma to jaws during tooth formation, by infection or by the effects of cytostatica and radiation during cancer treatment.6 There are more than 160 syndromes combined with hypo-dontia.6 Some of them are ectodermal dysplasia, Rieger syndrome and incontinentia pigmenti. In such cases morphological aberrancies as microdontia and conical crowns may be additional features.6 In addition to the number of lacking teeth, tooth eruption, occlusion and craniofacial parameters are influenced.