I R T
O R T H O D O N T OC S H O D O N T I C S
Two Cases of Molar Root Resorption
LISA YIP, HELEN FIONA MCKEOWN AND PAUL JONATHAN SANDLER
reduced enamel epithelium and dental
Abstract: The presence of unerupted teeth in close proximity to adjacent teeth can follicle of the impacted tooth may result
cause root resorption. The third molars and mandibular premolars are the most
in osteoclast recruitment and connective
frequent teeth to be impacted and the relationship between impacted teeth causing root
resorption of adjacent teeth has been well documented, but it is surprising how few tissue destruction and root resorption.7
studies have analysed the incidence of root resorption in these cases. This paper Much of the literature regarding root
discusses two patients who have undergone molar root resorption due to adjacent resorption has focused on the effect of
unerupted impacted teeth. impacted maxillary canines on maxillary
lateral incisors; incidence of root
Dent Update 2003; 30: 200-204 resorption of the incisors in such cases
Clinical Relevance: Unerupted teeth may lead insidiously to progressive is 12% in children of 10–13 years.8
migration, cyst formation and root resorption. The patient is often asymptomatic and, Although this may seem a significant
unless there are clinical signs to suggest abnormality in development, such pathology problem, the prevalence of impacted
is found as incidental findings on routine radiographs – by which time the prognosis of maxillary canines for the population as a
adjacent teeth may have been compromised. whole is only 2%,9 so the incidence of
root resorption of maxillary lateral
incisors caused by impacted maxillary
canines can be regarded as fairly low.
Nemcovsky et al.10 conducted a
survey of 186 radiographs of patients
T he teeth most frequently impacted
are the maxillary third permanent
molars, followed by the maxillary
The presence of retained or ankylosed
deciduous molars are an indication that
the permanent successor will be
with non-erupted third molars and found
radiographic evidence of root resorption
in 24.2% of second molars, of which
canines and mandibular premolars.1 malpositioned, impacted, poorly 6.5% showed moderate to complete root
Causes of second premolar impaction developed or even absent.4 resorption.
include: Causes of impaction of third molars No studies on the incidence of root
include:5 resorption caused by impacted second
l early extraction of second premolars have been documented.
deciduous molars, resulting in l insufficient skeletal development; Two case reports of patients who
mesial drift of the permanent l low correlation between maturation have undergone molar root resorption
molars;2 and of the third molar and skeletal due to adjacent unerupted impacted
l ectopic positioning of the development; teeth are reported below.
developing tooth bud.3 l excessive arch length, which
encroaches into the area of normal
third molar development.6 It is a CASE 1
Lisa Yip, BDS, MFDS RCS(Eng.), Senior House result of the lack of attrition A 15-year-old girl was referred to the
Officer, Oral and Maxillofacial Department, Helen
Fiona McKeown, BDS, FDS RCS(Edin.), MMedSci,
associated with a modern diet. orthodontic department regarding the
MOrth RCS(Eng.), Specialist Orthodontist, management of a deeply impacted |5.
Orthodontic Department, and Paul Jonathan The mechanisms by which impacted Three years previously she had
Sandler, BDS, FDS RCPS(Glasg.), MSc, MOrth teeth cause root resorption are unclear. undergone a course of orthodontic
RCS(Eng.), Consultant, Orthodontic Department, Various explanations have been treatment with upper and lower fixed
Chesterfield and North Derbyshire Royal
Hospital, Chesterfield, UK.
described in the literature, one of which appliances. Her orthodontist had taken
is that the secretion of cytokines by the the decision to leave the retained |e and
200 Dental Update – May 2003
O R T H O D O N T I C S
The patient presented with a Class
III incisor relationship on a mild Class
III skeletal base. He was in his early
mixed dentition and the d|d and |e were
present. The 4|4 and 7|7 were
unerupted. A decision was made to
Figure 1. Case 1: orthopantomogram showing review the situation annually to allow
Figure 3. The |5 spontaneously erupting into the
the |5 to be deeply and horizontally impacted. time for the lower deciduous molars to space of the permanent |6.
exfoliate and await the optimum time for
orthodontic treatment (Figure 6).
After 2 years, following the loss of obvious root resorption of 7|7 was
the deciduous teeth, a course of upper evident (Figure 8).
and lower fixed appliances was The patient did not then attend for 8
undertaken to retrocline the lower months, and it was not until 16 months
labial segment and close the spaces. after the decompensation that it
However, 12 months later the boy became clear that the 8| was mesially
began to grow rapidly, and it was felt and the |8 distally impacted against the
that, due to the worsening Class III roots of 7|7, the roots of which appeared
malocclusion, it would not be possible to have undergone gross resorption
to camouflage his skeletal pattern and (Figure 9). The roots of 21|12 . also
Figure 2. The |5 is rotating through 45° and
orthognathic surgery would be 4321|1234
starting to resorb the mesial root of the |6.
needed. The upper and lower fixed appeared shortened. A decision was
appliances were de-bonded and made for this to be monitored
retainers were fitted. At this point throughout his treatment.
the unerupted |5 because the latter was there was no clinical or radiographic The prognosis of the 7|7 was
horizontally and deeply impacted, with sign of root resorption of any of the compromised and they were extracted
no sign of root resorption (Figure 1). teeth. The crowns of 8|8 were during the orthognathic surgery. The 8|8
An orthopantomogram showed that developing (Figure 7). were kept in place to erupt into the
the |5 had rotated through 45°, Three years later, presurgical spaces of the 7|7: their eruption will be
uprighting itself, and had started to decompensation was commenced: no carefully monitored radiographically.
resorb the mesial root of the |6.
Unfortunately, the |8 was absent and
the |e had distal caries and resorbed a
roots (Figure 2).
A decision was made to extract |6 to
allow |5 to erupt in its place. The |e was
firm; it was thus restored and left in
situ. Twelve months following the
extraction, the |5 spontaneously
erupted into the space of the |6 (Figure
3) and after another 9 months was fully
erupted (Figure 4). The result did not
compromise the appearance anteriorly
(Figure 5). b c
It was decided that, once the |e
exfoliated, a bridge or an implant
would be provided in its space.
A 10 / -year-old boy was referred to
the orthodontic department regarding
the management of hypodontia. He Figure 4. (a) The |5 has fully erupted. (b) Clinical appearance: buccal aspect. (c) Clinical
appearance: occlusal aspect.
had congenital absence of the 54|45
Dental Update – May 2003 201
O R T H O D O N T I C S
apical position of the unerupted third
molar and a mesio angulation of 60° or
more with respect to the distal root of a
permanent second molar were
significantly associated with root
resorption of the permanent second
molar. Hence this study supported early
extraction of impacted third molars in
such cases. However, another study11 Figure 7. The crowns of 8|8 developing: there is
no sign of root resorption of 7|7.
Figure 5. The result did not compromise the showed that 39.3% of mesio-angulated
anterior appearance. upper third molars in 18-year-old
patients erupted by the age of 26 years.
The authors concluded that
radiographically apparent impaction in
late adolescence did not justify
prophylactic removal in the absence of
other clinical indications.
Despite the slight mesioangular Figure 8. Orthopantomogram taken 3 years
after presentation. There is no sign of root
impaction of 8| and the distoangular
resorption of 7|7.
impaction of |8, both of these teeth
Figure 6. Case 2: the orthopantomogram shows caused gross root resorption.
an early mixed dentition and the congenital Unfortunately, late detection of the close radiographic monitoring is vital
absence of 54 45.
55 advancing root resorption led to the to prevent avoidable loss of adjacent
necessity for removal of 7|7. permanent teeth.
Fortunately, the presence of the
DISCUSSION unerupted 8|8 meant that posterior
Unerupted second premolars have been function could be maintained by the
reported to have tremendous eruptive potential eruption of these teeth into ACKNOWLEDGEMENTS
and migratory potential and are the most the space. Many thanks to Mr Payne for his assistance in
providing and interpreting the tomographic views.
common teeth to migrate,2 as
demonstrated in Case 1. It is well
recognized that unerupted impacted CONCLUSION
teeth should be treated conservatively These two cases demonstrate the
unless there is evidence of their importance of identifying the risks of 1. Dachi SF, Howell FV. A survey of 3874 routine full
presence causing destruction to leaving unerupted impacted teeth. If a mouth radiographs II, a study of impacted teeth.
adjacent structures: where location of decision has been made to do so, Oral Surg 1961; 14: 1165–1169.
the unerupted impacted tooth is poor,
there is an increased likelihood of
surgery causing damage to adjacent
teeth and neurovascular tissue.
Figure 9. (a) Sixteen months later the 8|8
have impacted against the roots of 7|7,
Case I which have undergone gross resorption. (b)
Tomographic view confirming gross
The decision was made to leave the resorption of the upper permanent second
unerupted impacted |5 but, in view of the molar.
orientation of the crown and its
potential for eruption and migration,
leaving this tooth required close
radiographic monitoring. Late detection
of root resorption affected the
prognosis of |6 and its loss compromised
the result of the orthodontic treatment.
Nemcovsky et al.10 showed that an
202 Dental Update – May 2003
O R T H O D O N T I C S
2. Cryer BS. The unpredictable lower second succession, interproximal attrition, and Begg’s clinical signs of eruption disturbance. Eur J
premolar? BSSO 1965; 10–16. theory. Am J Orthod Dentofac Orthop 1990; 97: Orthod 1986; 8: 133–140.
3. Burch J, Ngan P, Hackmar A. Diagnosis and 349–357. 10. Nemcovsky CE, Libfeld H, Zubery Y. Effect of
treatment planning for unerupted premolars. 7. Nemcovsky CE, Tal H, Pitaru S. Effect of non- non-erupted third molars on distal roots and
Paed Dent 1994; 16: 89–95. erupted third molars on roots of approximal supporting structures of approximal teeth. A
4. Alling CC, Catone GA. Management of impacted teeth. A radiographic, clinical and histologic radiographical survey of 202 cases. J Clin
teeth. J Oral Maxillofac Surg 1993; 51: 3–6. study. J Oral Path Med 1997; 26: 464–469. Periodont 1996; 23: 810–815.
5. Varrela J. Occurrence of malocclusion in 8. Ericson S, Kurol J. Radiographic examination 11. Kruger E, Thomson WM, Konthasinghe P. Third
attritive environment: a study of a skull sample of ectopically erupting maxillary canines. Am J molar outcomes from age 18 to 26: findings
from Southwest Finland. Scand J Dent Res 1990; Orthod Dentofac Orthop 1987; 91: 483–492. from a population-based New Zealand
98: 242–247. 9. Ericson S, Kurol J. Radiographic assessment of longitudinal study. Oral Surg Oral Med Oral
6. Corruccini RS. Australian aboriginal tooth maxillary canine eruption in children with Pathol Oral Radiol Endodont 2001; 92: 150–155.
BOOK REVIEW who’s who in development of public
health theory and practice and some
Essential Dental Public Health. Blanaid excellent diagrams. This makes the book
Daly, Richard Watt, Paul Batchelor and incredibly useful to researchers and
Elizabeth Treasure. Oxford University ensures certain pages will be well
Press, Oxford, 2002 (£24.95). ISBN 0-19- thumbed. I personally wonder whether
262974-3 evidence-based dentistry and critical
appraisal of the literature actually
This book is a valuable addition to the belong in this book, since I see these as
bookshelf for anyone interested in generic skills in the clinical sciences.
dentistry beyond what happens directly That said, the former is well set into the
between dentist and patient. In their context of public health and it is quite
preface, the authors are overly modest rightly impossible to draw a precise line
and describe their book as intended dividing clinical and public health
primarily for undergraduate dental topics. Prevention is another topic that
students, though I feel it would benefit should permeate dentistry rather than be
postgraduate students, researchers and strength is added the excellent idea of owned by any particular group.
teachers of the discipline. regular discussion points, summaries A concise summary of dental public
The book covers a wide range of and learning outcomes for each chapter, health is never an easy thing to produce
topics within public health and public again making light work for busy and the authors are to be congratulated
health as applied to dentistry. As such, students (and their teachers!). A lot of for a well-constructed and readable
it presents ideas usually confined to trouble has been taken to attribute book.
generic public health texts and makes an several well-known concepts that are John Morris
excellent text on which to base an often quoted by others but matched University of Birmingham School of
undergraduate curriculum. To this basic with a reference, including a fascinating Dentisty
advantages over metal posts: they are valuable reading for busy dentists
ABSTRACT aesthetic, must be bonded to tooth contemplating a change in clinical
tissue, have a modulus of elasticity practice. The review suggests that the
STICK WITH THE NEW, OR STICK similar to dentine and appear to use of direct adhesive core build-up
WITH THE OLD? perform well in clinical studies. How maximizes retention and conserves
Tooth-Coloured Post Systems: A does the busy practitioner decide tooth tissue.
Review. A.J.E. Qualtrough and F. whether or not these should be Briefly, the authors conclude that
Mannocci. Operative Dentistry 2003; included in their clinical carbon fibre posts have generally been
1: 86–91. armamentarium? superceded by quartz, silica and glass
This comprehensive review sets out fibre-reinforced materials. These may be
For over 120 years, when faced with the criteria for the successful post, used in narrower cross-section than
the need for a post-retained crown, the and addresses how these criteria are gold, and also no longer require parallel-
vast majority of dentists in Great satisfied by the tooth-coloured sided preparation. A shorter, tapered
Britain have used gold. Recently, systems. The paper is design, far more in harmony with the
however, there has been considerable comprehensively referenced for the canal morphology, may be acceptable.
interest in tooth-coloured post student to take the subject to greater Peter Carrotte
systems. These have several depth, but the review would be Glasgow Dental School
204 Dental Update – May 2003