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).