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

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.