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Two Cases of Molar Root Resorption

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               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



                                                 and 5|5.
                                                   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
                                                                       7|7
                                                 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.


CASE 2
A 10 / -year-old boy was referred to
      1
          2


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
                                                                                           REFERENCES
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.


Case 2
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

				
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