be difficult to identify radiographically. Accessory roots have been reported to occur
in 1-9% of the primary dentition and from 1% to 45% of the permanent dentition.
There is an association between accessory roots and large cusps of Carabelli on the
maxillary first permanent molar and with accessory cusps on maxillary second and
third molars. In some cases the presence of accessory roots reflects macrodontia.
13.7 ABNORMALITY OF TOOTH STRUCTURE
13.7.1 All tissues
Arrested development of tooth-germs
Arrested development of tooth-germ formation may occur following such external
influences as trauma, ionizing radiation, osteomyelitis, or chemotherapy. The teeth
affected and the particular tissues affected will be dependent upon the nature and
timing of the insult. In teeth whose crowns are developing, this may result in enamel
defects and corresponding dentine defects may be seen on microscopic sections
should the tooth ultimately be extracted (820HFig. 13.10 (a) and (b)). If roots are
developing at the time of the insult these may appear stunted.
Locally, one or more permanent tooth-germs may be affected by infection from an
overlying primary predecessor. Such teeth are termed Turner teeth and typically have
areas of enamel hypoplasia and/or enamel hypomineralization. The mandibular
premolars are most commonly affected (821HFig. 13.19).
Regional odontodysplasia
This is an uncommon developmental anomaly, typically affecting the primary teeth
and corresponding permanent successors within a segment of the dentition. The
anterior teeth are more commonly affected than the posterior teeth and the defect may
cross the midline. The term 'ghost teeth' is sometimes applied to reflect the
radiographic appearance seen. Affected patients may present with abscesses prior to
the eruption of the teeth. The abnormal teeth have poorly developed crowns with
enamel and dentine changes, large pulp chambers, and open apices. The permanent
teeth may be less severely affected than the primary predecessors (822HFig. 13.20 (a) and
(b)).
Treatment
The removal of teeth affected by regional odontodysplasia is often necessary. As this
is often the case in the primary dentition, consideration then needs to be given to
management of the affected permanent successors. While there are reports of the
effective use of etch-retained restorations in these cases, the teeth are often slow to
erupt, with a distinctive local gingivitis, and the pulpal morphology is such that
infection is a frequent outcome. Root development may be slow but restoratively
useful. A case-by-case approach to treatment planning is required. Block removal of
unerupted teeth with surrounding bone is not required.