may fail to resorb. Although it has been suggested that there may be hypoplasia of
cementum on the roots of the teeth, this has not been definitively established. The
proportion of cellular to acellular cementum does not seem to be significant.
Hereditary gingival fibromatosis may be associated with delayed eruption,
presumably because of a local effect whereby the teeth are unable to penetrate the
enlarged and thickened gingivae. Other, truly localized causes of delayed eruption
include ectopic crypt position. This most often affects the maxillary or mandibular
permanent canines, or may present with the impaction of the maxillary first
permanent molars against the distal aspect of the adjacent primary second molar.
Local causes such as the presence of supernumeraries or odontomes may also
interfere with eruption of an adjacent permanent tooth (879HFig. 13.6 (a) and (b)). A delay
of more than 6 months between the eruption of a tooth and its antimere requires
investigation, most usually radiographically.
The position of the permanent canines, particularly those in the maxilla, should be
ascertained by palpation not later than the 10th birthday of the child. Any uncertainty
as to their presence or position should be followed by radiographic examination. The
potential for palatal impaction of these teeth may be identified by this simple measure
and simple intervention in selected cases, by the prompt removal of the primary
canine, may prevent the need for later surgery (880HChapter 14).
Delayed eruption of permanent teeth may also be due to dilaceration of developing
roots and crowns as a result of trauma to the primary dentition (881HChapter 12).
Early extraction of a primary tooth may be associated with delayed eruption of the
permanent successor due to thickening of the overlying mucosa.
Treatment
Any systemic condition may require treatment if this is available. Local obstructions
such as supernumerary teeth or odontomes need to be removed. Surgical exposure and
orthodontic traction may be necessary for late-presenting permanent canines and
patients with hereditary gingival fibromatosis may require gingivectomy.
In cleidocranial dysplasia, a combined restorative and surgical and occlusal
management approach to treatment planning is required. Retained primary teeth will
likely need to be extracted, together with the surgical removal of unerupted
supernumerary teeth. This requires careful treatment planning, as the successful
eruption of the permanent dentition cannot be guaranteed. Orthodontic treatment to
guide the teeth into occlusion may be one of the treatment options, with prosthetic
replacement of the teeth being considered should the teeth fail to erupt.
13.9 DISTURBANCES OF EXFOLIATION
13.9.1 Premature exfoliation
Premature exfoliation is always a cause for further investigation. Its association with
hypophosphatasia has been considered above (882HSection 13.7.4). Premature exfoliation