Poster abstract.

Objective: To evaluate permanent tooth-crown dimensions in prematurely born children and to compare the findings with full-term born controls. Methods: White preterm children of 8 to 10 years of age were selected from the Swedish Medical Birth Register. One group consisted of 36 extremely preterm children (born before the 29th gestational week), the other group included 37 very preterm children (born during gestational weeks 29 to 32). The preterm children were compared with a control group of 41 full-term born children, who were matched for gender, age, nationality and living area. Clinical examinations, study casts and panoramic radiographs were performed for each child. Permanent maxillary and mandibular first molars, central incisors and laterals were measured with a digital sliding calliper on study casts. The tooth-crowns were measured both mesiodistal and buccolingual. The examiner conducting the measurement analysis was unaware of the group to which the subject belonged. Results: The maxillary and mandibular first molars were smaller mesiodistally and buccolingually (p≤0.01) whereas central incisors and lower laterals were smaller mesiodistally (p≤0.02) in the extremely preterm group compared to the full-term group. A reduction in size of 5-8 % was found. The maxillary first molars and mandibular left first molar were also smaller mesiodistally (p≤0.035) in the extremely preterm group compared to the very preterm group. Conclusion: Premature birth is associated with reduced tooth-crown dimensions of permanent teeth.