The impact of premature birth on the permanent tooth size of incisors and first molars



Ebrahim E, Paulsson L.


Eur J Orthod. 2017 Nov 30;39(6):622-627. doi: 10.1093/ejo/cjx021.


BACKGROUND: Scientific evidence is insufficient to answer the question of whether premature birth causes altered tooth-crown dimensions. OBJECTIVE: To evaluate permanent tooth-crown dimensions in prematurely born children and to compare the findings with full-term born controls. SUBJECTS AND METHODS: Preterm children of 8-10 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 29-32). The preterm children were compared with 41 matched full-term born children. Clinical examination and study casts were performed on all children. Permanent maxillary and mandibular first molars, central incisors, and laterals were measured with a digital sliding caliper on study casts. The tooth-crowns were measured both mesio-distal and bucco-lingual. RESULTS: Both the mesio-distal and bucco-lingual measurements in the maxillary and mandibular first molars had a significantly smaller width in the extremely preterm group compared with the full-term group. The central incisors and lower laterals were significantly smaller mesio-distally in the extremely preterm group compared to the full-term group. A reduction in tooth size of 4-9% was found between the extremely preterm group and the full-term group for both boys and girls. The maxillary first molars and mandibular left first molar were also smaller mesio-distally in the extremely preterm group compared to the very preterm group. The results indicate that the more preterm the birth, the smaller the tooth-crown dimensions. Independent of gestational age girls had generally smaller teeth than boys. CONCLUSION: Premature birth is associated with reduced tooth-crown dimensions of permanent incisors and first molars. CI – © The Author 2017. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email:

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Link/DOI: 10.1093/ejo/cjx021