The impact of premature birth on the mandibular cortical bone of children.

SUMMARY

Children born prematurely often have reduced skeletal mineralization. The aim in this study was to compare the cortical thickness of the lower jaw on radiographs of 8- to 10-year-old children with histories of preterm or full term births. There were no significant differences in cortical thickness between full term and preterm children at this age.

INTRODUCTION

The purpose of this study was to compare the cortical thickness of the mandible on panoramic radiographs of 8- to 10-year-old children with histories of preterm or full term births.

METHODS

Panoramic radiography was performed on 36 extremely preterm, 38 very preterm and 42 full term children at the age of 8 to 10 years. Five observers independently measured the mandibular cortical width on the panoramic radiographs at four defined sites bilaterally. Altogether, 928 sites were available. Measurements were performed twice on a random 24% of the sites by four observers. One-way analysis of variance with Tukey's post hoc test was used to test differences between groups. Intraclass correlation coefficient (ICC) was calculated for interobserver agreement while intra-observer agreement was expressed as measurement precision.

RESULTS

Significant differences of mandibular cortical width were found between extremely preterm and very preterm children for five of the eight measurement sites with the very preterm showing the highest value. No significant differences were found between full term and either very preterm or extremely preterm except for one measurement site, with the extremely preterm showing the lowest value. ICC varied between 0.30 and 0.83 for the different sites (mean 0.62). The precision of a single measurement varied between 0.11 and 0.45 mm (mean 0.25 mm).

CONCLUSIONS

From the evidence that very preterm children had significantly thicker mandibular cortices than extremely preterm children, we suggest that these findings may reflect the effect of mineral supplementation provided to premature infants, causing a 'shifting up' of bone mineral status relative to the full term peer group while maintaining the difference between very preterm and extremely preterm born children.