Incidence and distribution of deciduous molar ankylosis, a longitudinal study.

AIM: To study incidence and distribution of deciduous molar ankylosis. MATERIALS AND METHODS: study design: longitudinal retrospective study. A total of 512 consecutive subjects (aged 5 to 15 years) were examined at the Orthodontics and Paediatric Dentistry Department of the Genoa University School of Dentistry; for each subject an ortopantomography x-ray was taken. RESULTS: Thirty-four children were affected by deciduous molars ankylosis (6.6%). A statistically significant difference was revealed between the distributions: the lower deciduous molars were ankylosed more frequently than the upper ones (P < 0.001); the second deciduous molars were ankylosed more frequently than the first molars (P < 0.001). No statistical significance was found between sex and number of infraoccluded teeth (P = 0.74). CONCLUSION: This study found an incidence of deciduous molar ankylosis of about 6.6%; the lower deciduous molars and second deciduous molars were ankylosed more frequently (P < 0.001).