Natal and neonatal teeth: Histologic investigations in two brothers

Abstract

The literature on teeth present at birth or erupting immediately after birth is surveyed briefly. A report is given of the eruption of the first tooth in three brothers. The oldest one got his teeth at the normal time. The second boy had a lower incisor that erupted nine days after birth (“neonatal tooth”). This tooth was shed when the boy was 6 years old, and it was a little smaller than the other lower incisors. The youngest boy had two lower incisors present at birth (“natal teeth”) which, however, were removed nine days later. The present article deals with the histologic investigation of the two natal teeth and the neonatal tooth mentioned. In the natal teeth the enamel, in which mineralization has not been accomplished, comers only the incisal two-thirds of the crown, while the cervical third is covered by cementum. Extensive enamel caries developed during these nine days when the boy was nursed solely by his mother. Signs of caries in the dentine could also be observed. In the dentine the incisal half is otherwise normal, while the cervical half shows a most irregular structure, namely, dentinal tubules decreasing in length toward the cervix, where they disappear completely, and further cell inclusions in empty spaces in the mineralized matrix. In the part of the dentine covered by cementum there is a peripheral zone of interglobular dentine with very small globuli. In the part of the dentine covered by enamel, the peripheral zone is normal. It is true of the whole bulk of dentine that any incremental pattern is hardly visible. Neither are the semilunar formations, visible in polarized light and indicative of spherical mineralization, present in their ordinary pattern. The dentinoenamel junction does not have the normal scalloped appearance. At the cervix the dentine shows a deposition of more or less regular bone tissue assuming the form of a root. No Hertwig's sheath is present. The cause of the formation of the irregular dentine and the bony root is supposed to be mechanical irritants due to the mobility of the tooth. The absence of Weil's zone and the cell-rich zone in the pulp is not pathologic, but is in accordance with a normal. stage of development. An ascending pulpitis deriving from accumulations of bacteria in the basal pulp border can be established. These bacteria must have come from the oral cavity through the periodontal tissue in the same way as in deciduous teeth prior to their shedding. The neonatal tooth described has a root with extension as to be expected in a normal shedding tooth. A broad zone with spaces occupies the exterior part of the root dentine. The cervical third of the enamel is hypoplastic and hypomineralized. The familial tendency indicates that in these two brothers the natal and neonatal teeth have been formed in superficial position due to a genetic factor.