Scanning Electron Microscopy and Macroscopic Examination of Prematurely Erupted Teeth in Preterm Infants

Prematurely erupted teeth are rare in full-term neonates and extremely rare in prematurely delivered infants. The aim of this study was to present macroscopic and scanning electron microscopy (SEM) investigations of prematurely erupted prima-ry teeth of preterm very low birthweight (VLBW) and extremely low birthweight (ELBW) infants. Three preterm VLBW and ELBW infants with pre-maturely erupted lower incisors were examined. The dental examination assessed the type, location, clini-cal appearance, and degree of mobility of the prema-turely erupted teeth. The structural appearance of enamel and dentin of three extracted and longitudi-nally sectioned prematurely erupted teeth was inves-tigated with scanning electron microscopy (SEM). Lower incisors were rootless with hypermobility. The surface of enamel of the prematurely erupted primary teeth was hypoplastic and hypomineralized and had a typical "honeycomb" appearance in SEM. The aprismatic type of enamel was visible in some regions. The neonatal line separating the layer of prenatal enamel from postnatal enamel was ob-served. The enamel prisms were interconnected by interprismatic substances, and cross-striations of prisms were visible. Dentin presented a typical tubu-lar character. The dentinal layer near the enamel dentin junction had Y-shaped branching of dentinal tubules. On the pulpal side, dentin had a globular character. The macroscopic and SEM investigations particularly revealed alterations in enamel, while the dentin of neonatal teeth had a nearly normal appearance.