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1. ROOT RESORPTION
INDIAN DENTAL ACADEMY
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2. Root resorption. Part 1 - Brezniak and
Wasserstein
-AJO-DO 1993 Jan
Andreasen defines three external root
resorption types:
Surface Resorption
2. Inflammatory Resorption
3. Replacement Resorption
1.
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3. 1) Surface resorption
-Self-limiting process, involving small outlining areas
followed by spontaneous repair.
-Stimulation is minimal and for a short period.
-This defect is usually undetected radiographically and
is repaired by a cementum-like tissue.
-Commonly seen after orthodontic treatment is surface
resorption.
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4. 2)Inflammatory resorption

Where initial root resorption has reached
dentinal tubules of an infected necrotic pulpal
tissue or an infected leukocyte zone.

Transient inflamatory resorption-common after
Rx

Progressive inflammatory resorption. When
stimulation is for a long period .
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5. 3) Replacement resorption,
Bone replaces the resorbed tooth material
that leads to ankylosis -rarely seen after
orthodontic treatment.
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6. PROFITT- Three external root
resorption types:

1) Moderate Generalized-long Rx duration

2) Severe Generalized –
-evidence of resorption before Rx
-thyroid harmone
-etiology???

3) Severe Localized-may be caused due to ortho Rx-cortical plates
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7. IMPORTANT CONSIDERATIONS

Cementum is more resistant to resorption compared
with bone. However, resorption of the cementum and
dentin may also occur.

Breach in the formative cell layer covering the tissue,
or when the precementum is mechanically damaged

Denuded root areas attract hard tissue resorbing
cells .
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8. IMPORTANT CONSIDERATIONS

The cementoclast- demineralization of the calcified
tissue and degradation of the organic matrix after
demineralization

Resorbing activity-characterized by synthesizing
prostaglandin E with concomitant increase in cAMP.
This process is regulated by hormones (parathyroid,
and calcitonin).
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9. IMPORTANT CONSIDERATIONS

Relates surface resistance to the innermost cellular
layer of the periodontal ligament. This layer supplies
the protective mechanism to the root, as well as the
potential for a repair.

The cementoblasts, fibroblasts, osteoblasts,
endothelial, and perivascular cells are included in this
layer
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10. IMPORTANT CONSIDERATIONS

occurs even in teeth where deposition of mineralized
material was prevented.

May be resorbed directly or indirectly. Indirect
resorption is seen as undermining resorption— from
howship lacunae of the dentin.

Resorbed lacunae -mainly on the pressure side.

After it can take between 10 and 35 days for
resorbed lacunae to appear on application of force.
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11. IMPORTANT CONSIDERATIONS


According to Schwartz when pressure decreases
below the optimal force (20 to 26 g/cm2) root
resorption ceases. Reitan and Rygh are in agreement
that cementoid fills those resorbed lacunae.
Repair of resorbed lacunae is seen after 35 to 70
days of force application.
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12. Root resorption during orthodontic
therapy(Edward F. Harris- Seminars in orthodontics:2000)

Albert ketcham- 1st to notice

Orthodontically induced resorption occurs adjacent to
the hyalinized zone and occurs during and after the
elimination of the hyaline tissues.

Removal of hyalinized tissue leaves raw surface
exposed to the dentinoclasts.
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13. Prevalence
Rudolph noted the resorption typically attacks the
root tip and travels coronally leading to the “shed
roof” effect.

Incisors-move the most / single-root spindly cone
shape. Single rooted.

Acellular/ cellular cementum:more at the apex where
there is cellular cementum.

Teeth with thick cementum – less.
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14. Measurement Method

EARR-defined operationally as the degree a root has
shortened from its original length by clastic activity.

Methods used to quantify resorption-visually assesed –calipers
-light /electron microscopy
-capture image with scanner or import image from
digital x ray machine and make measurement on a
software.

IOPAs using long cone technique.
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16. 
Dermaut and De Munck.

CrownA x RootB/RootA x CrownB = RootB/RootA
A and B are two examinations, such as pre treatment
and post treatment.

Similar ratios – Linge n Linge, Nanda and
Costapoulos.
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17. 
Cells involved- odontoclast- multinucleated cell
formed by monocyte precursors-local tissue
contribution???
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18. Root resorption after treatment Part 2 - Brezniak and
Wasserstein
-AJO-DO 1993 Feb (138-146):
FACTORS AFFECTING RESORPTION

1.
2.
3.

Biologic factors
Metabolic signals that generate changes in the
relationship between osteoblastic and osteoclastic
activity include
Hormones
Body type
Metabolic rate.
Genetics no definite genetic conclusion.( Heritability
estimate of 70% - Edwards article- Clinical significancesearch for biochemical markers ).
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19. FACTORS AFFECTING RESORPTION

Systemic factors. endocrine problems including
hypothyroidism, hypopituitarism, hyperpituitarism
-hormonal imbalance does not cause but influences
the phenomenon.

secondary hyperparathyroidism is not primarily
responsible for increased root resorption-recent
study.

Study - parathyroid hormone plays a major role in
bone metabolism.
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20. FACTORS AFFECTING RESORPTION



Calcium ions are reputed to play an important
role in mediating the effects of external stimuli
(force, hormones) on their target cells.
Nutrition.Becks demonstrated root
resorption in animals deprived of dietary
calcium and vitamin D. It was later suggested
-not a major factor -Controversial results.
Chronologic age. All tissues involved in the
root resorption process show changes with
age.
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21. FACTORS AFFECTING RESORPTION

The periodontal membrane becomes less
vascular, aplastic, and narrow, the bone more
dense, avascular, and aplastic, and the
cementum wider. (woods et al and bishara
carried out independent studies to find out the
relation bw age and root resorption and found
none-Edwards Article).

Gender. No correlation between gender and
root resorption
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22. FACTORS AFFECTING RESORPTION

Ortho treatment - Study reports that the incidence of
root resorption increased from 4% before orthodontic
treatment to 77% after treatment.

Habits. Nail-biting, tongue thrust associated with
open bite, and increased tongue pressure (finger
sucking-Edwards article).
Tooth structure. Deviating root form is more
susceptible to postorthodontic root resorption.

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23. FACTORS AFFECTING RESORPTION


Convergent apical root canal is considered to
be an indicative of high root resorption
potential.85 The degree
Root resorption in teeth with blunt- or pipetteshaped roots was significantly higher than in
teeth with normal root form - most susceptible
root form to root resorption.
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24. (Levander
and malmgren –assessment of ot form-add
picture
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25. FACTORS AFFECTING RESORPTION


Previously traumatized teeth. Traumatized
teeth can exhibit external root resorption
without orthodontic treatment.
Orthodontically moved traumatized teeth with
previous root resorption are more sensitive to
further loss of root material.The average root
loss for
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26. FACTORS AFFECTING RESORPTION

Trauma patients after orthodontic therapy was 1.07
mm compared with 0.64 mm for untraumatized teeth.

Endodontically treated teeth.
A higher frequency and severity of root resorption of
endodontically treated teeth during orthodontic
treatment was reported –
???? endodontically treated teeth are more resistant
to root resorption because of an increased dentin
hardness and density.
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27. FACTORS AFFECTING RESORPTION

More dense the alveolar bone, the more root
resorption occurred during orthodontic treatment.

Number of which increases according to the number
of marrow spaces. controversial result.

Maxillary teeth are more sensitive than mandibular
teeth -maxillary incisors probably due to the distance.
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28. FACTORS AFFECTING RESORPTION


Root structure and relationship to bone and
periodontal membrane tend to transfer the forces
mainly to the apex .
The most frequently affected teeth, according to
severity, are the maxillary laterals, maxillary centrals,
mandibular incisors, distal root of mandibular first
molars, mandibular second premolars, and maxillary
second premolars.
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29. Mechanical factors

Appliances.
1)Fixed versus removable:fixed appliances is more
detrimental to the roots .

Ketcham claimed that normal function is disturbed by
the splinting effect of orthodontic fixed appliances over a
long period that can cause root resorption.

Stuteville, on the other hand, suggested that the jiggling
forces caused by removable appliances are more
harmful to the roots.
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30. Mechanical factors

2)Begg versus edgewise: It is often stated that the
light wire Begg technique causes less root resorption
than edgewise, although maxillary incisor root
resorption during the Begg third stage has been
documented.

3) Magnets: It is suggested that the increase in force
as space closes with time (attraction) can stimulate a
more physiologic tissue response, and thus decrease
the potential for root resorption.
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31. Mechanical factors

4)Intermaxillary elastics: Linge and Linge found
significantly more root resorption on the side where
elastics were used

5) Extraction versus nonextraction: McFadden and
Vonder found no difference

6) Other appliances:Rapid maxillary expansion, with
cervical traction, has been reported to cause severe
root resorption of the first maxillary molars.
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32. Mechanical factors

Orthodontic movement type.. Intrusion is probably the
most detrimental to the roots involved. Bodily movement
should be less than that of tipping.

Orthodontic force-higher stress causes more root
resorption The extent of tooth movement: Root
resorption is directly related to the distance moved by
the roots.
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33. Combined biologic and mechanical factors

Treatment duration. Most studies report that the
severity of root resorption is directly related to
treatment duration.

Relapse. Teeth are prone to additional root loss
during relapse as a result of light muscles forces

Occlusal force -Heavy mastication, occlusal trauma.
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34. Other considerations

Loss of crestal bone and tooth stability.

3 mm of root resorption is approximately
equivalent to 1 mm of crestal bone loss.
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35. Clinical considerations related to
root resorption

1. Informed that apical root shortening (root resorption)
may be a consequence of orthodontic treatment.

2. Periapical radiographs:

(a.) Periapical radiographs -important orthodontic
records as any pretreatment record, and are particularly
useful to compare pretreatment and post treatment.
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36. Clinical considerations related to
root resorption
(b.) Impossible to predict the onset of root
resorption, periodic control radiographs are
indicated. Once every year after appliance
placement (6 months-Edwards article).
(c.) Post treatment radiographs essential assess the bone/root integrity after treatment.
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37. Clinical considerations related to root
resorption

3. Orthodontic treatment timing.
Early as possible since there is less root
resorption in developing roots and young patients
show better muscular adaptation to occlusal
changes.

4.Resorption is detected during treatment – goals
must be reassessed.
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38. Clinical considerations related to
root resorption

A decision should be made –
1) Terminate the treatment
2) Arrive at a treatment compromise.
3) When necessary, applied forces should be
stopped and/or a bite plane used to disocclude the
teeth.

6. Habits such as nail biting or tongue thrust
should be stopped.
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39. Clinical considerations related to
root resorption

7. All types of tooth movement can cause root
resorption. It seems that intrusion is the most
detrimental.

8. Occlusal traumatism and jiggling are detrimental
-finish treatment with a correct occlusion.

9. It is essential to recognize anatomic and
physiologic limitations. Surgical intervention may be
required.. –
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40. Clinical considerations related to
root resorption

10. Teeth with resorbed roots - abutments to bridges
only when their root length exceeds the clinical crown
length

11. Orthopedic effect in the early treatment phase
has less destructive potential on the roots compared
with the dentoalveolar effect at a later treatment
phase

12. Root resorption - weighed against appliance
efficiency and individual treatment objectives.
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41. Clinical considerations related to
root resorption



13. Treatment time - short as possible
14. Traumatized teeth - treated cautiously.
15. Medical examination and familial tendency records
- especially in cases of severe resorption.
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42. Clinical considerations related to
root resorption

16. Root resorption continues after appliance removal
or during retention, sequential root canal therapy
-calcium hydroxide. G-p filling -only after root
resorption ceases

17. Full-mouth radiographs when receiving a transfer
case.
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43. Thank you
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Leader in continuing dental education
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