Background and objectives Tooth agenesis is the most common developmental anomaly in humans. The reported prevalence of permanent dentition tooth agenesis excluding the third molars was 15.7% for European population. Syndrome and isolated forms of tooth agenesis have been described and can occur sporadically or in families showing etiologic heterogeneity. The study aims were to describe the variability of clinical phenotypes, to observe similarities/differences of familial tooth agenesis forms among affected relatives, to characterise the mode of inheritance and to identify distinct groups of patients for further molecular investigations.

Patients and Methods A total of 2305 subjects were included in the study. Clinical and radiographical assessments were performed, followed by detailed investigation into the personal and family medical history of the patients with tooth agenesis. If necessary chromosome or molecular tests were performed.

Results Tooth agenesis was observed in following two forms, hypodontia and oligodontia. More severe expression of both syndromic hypodontia and oligodontia were noticed comparing with non-syndromic tooth agenesis. All teeth were affected but not equally. Tooth agenesis was found in conjunction with other dental anomalies. In many genetic syndromes there is a typical pattern of dental agenesis but comparative analysis of patterns of dental agenesis revealed common, rare and individual dental findings.

Conclusions Predictive genetic testing has potential for accurate risk assessment in families with a history of tooth agenesis that may be inherited. Using the results of these tests, the dentist will be able to develop a targeted prevention plan to minimise the functional complications and aesthetic and psychological stress.