13.7.4 Cementum defects
The cementum can be affected in a number of genetic disorders. The consequences of
alterations in cementum can have profound effects on the fate of the dentition.
There are a number of rare but significant conditions associated with the early loss of
primary teeth. Any case of early or spontaneous loss of teeth is a cause for further
investigation. In one of these, hypophosphatasia (both autosomal dominant and
autosomal recessive inheritance are known), there may be premature exfoliation of the
primary teeth or loss of the permanent teeth. The serum alkaline phosphatase level is
low; phosphoethanolamine is excreted in the urine. Histopathological examination in
hypophosphatasia will show aplasia or marked hypoplasia of the cementum. There
may also be abnormal dentine formation with a wide predentine zone and the
presence of interglobular dentine (similar to vitamin D-resistant rickets).
Treatment
Local measures such as scrupulous oral hygiene may slow the loss of teeth in cases of
hypophosphatasia but the prime focus of treatment may be the replacement of teeth of
the primary and permanent dentitions as they are lost.
13.8 DISTURBANCES OF ERUPTION
13.8.0 Introduction
Considerable variations exist in the timing of eruption of the permanent dentition.
There may be some racial variation and eruption may also be influenced by
environmental factors such as nutrition and illness. Eruption times of permanent teeth
in females tend to be slightly ahead of the corresponding eruption times in males; this
becomes a more marked difference with the later erupting teeth.
13.8.1 Premature eruption
Some families report that early tooth eruption is a family feature. Children with high
birth weight have been reported to have earlier eruption of their primary teeth than
children with normal or low birth weights. Early eruption of the permanent dentition
may occur in children with precocious puberty and children with endocrine
abnormalities, particularly those of the growth or thyroid hormones.
Natal and neonatal teeth
Teeth present at birth are known as natal teeth and those that erupt within the first
month of life as neonatal teeth. Approximately one in 2000-3000 live births are so
affected. The mandibular central incisor is the most common natal or neonatal tooth.
Occasionally maxillary (central) incisors or the first molars may appear as natal teeth.
The vast majority of cases represent premature eruption of a tooth of the normal
sequence. It has been suggested that this condition is a result of an ectopic position of
the tooth-germ during foetal life.
Natal or neonatal teeth may also be seen in association with some syndromes