RESEARCH – May 2007

Eruption of primary teeth and the relationship among several neonatal factors in preterm children


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Many studies have shown a delay of dental eruption in primary dentition and have attempted to find out its causes in prematurely born children. Although primary teeth eruption is delayed in preterm children, there is no difference in eruption timing compared with full-term infants after correcting the child`s age.
The aim of the study was to determine the primary teeth eruption pattern in preterm children with birthweight below 2500 g in Estonia and to investigate the influence of different neonatal factors, such as birthweight, breastfeeding, rachitis, anaemia, sepsis, orotracheal intubation and tube feeding on primary teeth eruption.
Patients and Methods: 72 prematurely born children (31 boys and 41 girls) with a mean gestational age of 31.1 (24-35) weeks and a birthweight of 1660 (600-2443) g were studied. The children were divided into two groups according to birthweight: less than 1500 g and 1501-2500 g. Twenty-three children born at term with a normal birthweight served as the controls. Data were collected retrospectively from medical records and prospectively by interviewing the mothers. Analyses were made using both chronological and corrected ages for the prematurely born group.
Results. The appearance of the first primary tooth occurred significantly later in the preterm group compared with the controls (8.9 vs 6.6 mo, p<.0001) and retardation of dental eruption at the age of one year was found (4.8 vs 7.6 teeth in full-term infants, p=.0004) when chronological ages were considered. A nonsignificant difference occurred when corrected ages were used. There was a significant delay of primary teeth eruption in children with birthweight less than 1500 g in the first year of age. The eruption of the first tooth occurred after the 10th month of age in 38.5% of the children with birthweight below 1500g and in 15.2% of the children with a birthweight of 1501-2500 g (OR 3,6, 95% CI 1,163-11,299). The eruption of the first tooth in preterm children was earlier in those who received breast milk up to 3 months compared with the nonbreastfed children. Neonatal intubation time more than 5 days had a significant negative impact on teething. Rachitis, sepsis, anaemia and tube feeding showed no significant impact on teething.
Conclusions. The factors related to severity of neonatal illness, postnatal nutrition and birthweight less than 1500 g in prematurely born children affect the timing of primary tooth eruption and dentition during the first year of life.