Root resorption final1

ROOT RESORPTION
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Cementum
 Cementum as a unit is composed of –
1. Cementoblasts
2. Cementoid
3. Fully mineralized cemental tissue

 Classification :
a) Cellular cementum (apical 1/2- 2/3 )
b) Acellular cementum (coronal 1/2 –2/3 )
 Based on the presence of collagen
fibres-
a) Fibrillar
b) Afibrillar
Cementum
C
D

 Cementoblasts- origin- precursor cells –
dental sac.
 Cementoid-lined by cementoblasts
 Sharpeys fibres
Cementum

 Cementum is more resistant to resorption
compared with bone.
 Breach in the formative cell layer covering the
tissue, or when the precementum (cementoid)
is mechanically damaged.
 Denuded root areas attract hard tissue
resorbing cells .
Cemental resorption

 The cementoclast- ??? Origin –precursor cells .
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).
Cemental resorption

 Surface resistance - cementum is due to the
innermost cellular layer of the periodontal ligament.
1. - protective mechanism
2. -potential for repair
a) Cementoblasts
b) Fibroblasts
c) Osteoblasts
d) Endothelial
e) Perivascular cells
Cemental resorption

 The cementum may be resorbed
-directly
-indirectly.
 Indirect resorption is seen as undermining resorption
— from Howship lacunae of the dentin.
 Resorbed lacunae -mainly on the pressure side.
 Takes between 10 and 35 days for resorbed lacunae
to appear on application of force.
Cemental resorption

 Schwartz - below the optimal force (20 to 26 g/cm2)
root resorption ceases.
 Reitan and Rygh - cementoid fills those resorbed
lacunae.
 Repair of resorbed lacunae is seen after 35 to 70
days of force application.
Cemental resorption

Histological illustration of varying
degrees of repair in orthodontically
induced root resorption in maxillary
premolars after 1 to 8 weeks
retention.
A. Root surface in the cervical third
ofthe root with normal dentin (d),
acellular root cementum (c), and
periodontal ligament (p).
B. Undermined root resorption in the
cervical third of the root. Dentin (d),
cementum (c), periodontal ligament
(p).
C. Partial repair with acellular
cementum (ac) in the cervical third
of the root. Dentin (d).

D. Partial repair with cellular
cementum (cc) in the apical third of
the root. Dentin (d).
E. Functional repair with
cellular cementum (cc) in the apical
third of the root. Dentin (d).
F. Anatomic repair with
acellular cementum (ac) in the
middle third of the root. Dentin (d)

Andreasen defines three external root
resorption types:
1. Surface Resorption
2. Inflammatory Resorption
3. Replacement Resorption
Cemental 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.
1) Surface resorption

 Where initial root resorption has reached
dentinal tubules of an infected necrotic pulpal
tissue or an infected leukocyte zone.
1. Transient inflamatory resorption-common
after Rx
2. Progressive inflammatory resorption. When
stimulation is for a long period .
2)Inflammatory resorption

3) Replacement resorption,
Bone replaces the resorbed tooth material
that leads to ankylosis -rarely seen after
orthodontic treatment.

PROFITT- Three external root
resorption types:
 1) Moderate Generalized-
-long Rx duration
 2) Severe Generalized –
-evidence of resorption before Rx
-etiology???
 3) Severe Localized-
-may be caused due to ortho Rx-cortical plates

Root resorption during orthodontic
therapy-
 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 ??

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.
 Acellular/ cellular cementum:more at the apex where
there is cellular cementum.
 Teeth with thick cementum – less.

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.

LEVANDER E MALMGREN

Categories of root resorption:
(A)Slight blunting–Category 1
(B) Moderate blunting–Category 2
(C) Severe blunting

 Dermaut and De Munck.
 CrownA x RootB= RootB=1
RootA x CrownB RootA
A and B are two examinations, such as pre treatment
and post treatment.
 Similar ratios – Linge n Linge, Nanda and
Costapoulos.
Measurement Method

 Biologic factors
 Genetics no definite genetic conclusion was found
possible.
 Heritability estimate of 70% - Edwards article- Clinical
significance-search for biochemical markers .
 Systemic factors. endocrine problems including
hypothyroidism, hypopituitarism, hyperpituitarism
-hormonal imbalance does not cause but influences the
phenomenon.
FACTORS AFFECTING RESORPTION

 Calcium ions are reputed to play an important role in
mediating the effects of external stimuli 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.

 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. Treated and untreated random samples
showed no correlation between gender and root
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.

 Convergent apical root canal is considered to
be an indicative of high root resorption
potential.
 Root resorption in teeth with blunt- or pipette-
shaped roots was significantly higher than in
teeth with normal root form - most susceptible
root form to root resorption.

 Root form - normal (N), blunt (A), eroded (B), pointed (C), bent (D), bottle
shaped (E).
AJO-DO 1995 Jul : Risk factors of root resorption Mirabella and Årtun
LEVANDER E MALMGREN

 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.

 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.

Orthodontic treatment of patient with and without endodontically treated central incisor. AJO-
DO 1995 Jul (48-55) : Risk factors of root resorption Mirabella and Årtun
.
Endodontically Treated Teeth

Endodontically treated incisors resorb with less frequency and severity than vital
control teeth.
Endodontically Treated Teeth

 More dense the alveolar bone, the more
root resorption occurred during orthodontic
treatment.
 Maxillary teeth are more sensitive than
mandibular teeth -maxillary incisors probably
due to the distance.

AJO-DO 1995 Jul (48-55)
PROXIMITY TO THE PALATAL CORTEX

 The most frequently affected teeth, according to
severity-
1. Maxillary laterals
2. Maxillary centrals
3. Mandibular incisors
4. Distal root of mandibular first molars
5. Mandibular second premolars
6. Maxillary second premolars.

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.
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)Extraction versus nonextraction:
McFadden and Vonder found no difference
Mechanical factors

 Scott et al-Angle Orthod- Association of appliance type
and tooth extraction with the incidence of external apical
root resorption (EARR) of posterior teeth following
orthodontic treatment.
 EARR was 2.30 times higher for Begg appliances
.compared with edgewise.
 3.72 times higher where extractions were performed.
Mechanical factors

 A 4-grade ordinal scale, modified from Sharpe et al was used to
determine -degree of EARR as follows:
0 = no apical root resorption
1 = slight blunting of the root apex
2 =moderate resorption of the root apex beyond blunting and up to one
third of the root length
3 = excessive (severe) resorption of the root apex beyond one third of
the root length.
Mechanical factors

 4) 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.
 5)Intermaxillary elastics: Linge and Linge
found significantly more root resorption on the
side where elastics were used
Mechanical factors

Continuous vs discontinuous force
application- Ahu acar-1999-AO
Reitan –light interrupted forces
help to prevent excessive root
resorption rest periods help repair
of lacunae
Buccal aspect

PALATAL ASPECT
Continuous vs discontinuous force
application- Ahu acar-1999-AO

 6) Other appliances:Rapid maxillary expansion with
cervical traction, has been reported to cause severe root
resorption of the first maxillary molars.
 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
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.
Combined biologic and mechanical factors

 Loss of crestal bone and tooth stability.
 3 mm of root resorption is approximately
equivalent to 1 mm of crestal bone loss.
Other considerations

 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.
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.
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.
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.
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.. –
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.
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.
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.
root resorption

REFERENCES
 Root Resorption During Orthodontic Therapy- (Edward F. Harris-
Seminars In Orthodontics:2000)
 Root Resorption After Treatment Part 2 - Brezniak and Wasserstein-
AJO-DO 1993 jan (138-146)
 Root Resorption After Treatment Part 2 - Brezniak and Wasserstein-
AJO-DO 1993 Feb (138-146)
 Repair of orthodontically induced root resorption in adolescents Py
Owman-Moll, Jüri Kurol, Dan Lundgren.
1997 Angle orthodontist, inc.1995

 Current principles and techniques -Graber
Vanarsdall
 Contemporary orthodontics-Profitt
REFERENCES

Root resorption final1

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