Root resorption is a common side effect of orthodontic treatment that has been recognized since the 1800s. It occurs when forces applied during tooth movement cause damage to the root surface. Most patients experience some degree of resorption, though it is typically minor and clinically insignificant. Risk factors include longer treatment times, use of heavier forces, intrusion movements, and patient characteristics like age. Diagnosis is usually via radiographs, and prevention focuses on limiting risk factors like force magnitude and duration.

1. Root Resorption In
Orthodontics
Dr. Kiran Saju
IInd Year
Department of Orthodontics and Dentofacial Orthopedics

2. History
• First discussed by Bates(1856)
• Resorption – Dr Broomwell
• Has been the major concern to Orthodontists since
1927(Ketcham).
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 1. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Jan 1;103(1):62-6
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 2. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Feb 1;103(2):138-46.

3. Definition
• Root resorption is defined as microscopic areas of
resorption lacunae visualized with histologic
techniques. (Hartsfield et al. 2004)
• EARR- external root resorption .
• OIIRR- orthodontically Induced inflammatory root
resorption . (Brezniak Wasserstein& Aviv. 1993)
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 1. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Jan 1;103(1):62-6
Hartsfield Jr JK, Everett ET, Al-Qawasmi RA. Genetic factors in external apical root resorption and
orthodontic treatment. Critical Reviews in Oral Biology & Medicine. 2004 Mar;15(2):115-22.

4. Incidence
• Around 90% of patients will experience resorption
but in most cases this is insignificant (Weltman et al
2010)
• Some degree is inevitable during treatment with fixed
appliance but is unpredictable and variable. It can be
severe (Killany 1999)
Weltman B, Vig KW, Fields HW, Shanker S, Kaizar EE. Root resorption associated with orthodontic tooth
movement: a systematic review. American journal of orthodontics and dentofacial orthopedics. 2010
Apr 1;137(4):462-76.
Killiany DM. Root resorption caused by orthodontictreatment: An evidence-based review of literature.
InSeminars in orthodontics 1999 Jun 1 (Vol. 5, No. 2, pp. 128-133). WB Saunders.

5. Consolaro A. Extreme root resorption in orthodontic practice: teeth do not have to be replaced with
implants. Dental Press Journal of Orthodontics. 2019 Nov 11;24:20-8.
Oliveira AG. Análise de fatores preditivos da reabsorção dentária radicular no tratamento ortodôntico.
Campinas, SP: [s.n.]; 2010.

6. • Particularly affects 11,12,21,22,31,32,36,41,42,46
(Kennedy et al 1983)
• Mean loss 1.5mm (Linge & Linge 1983)
– Maxilla 2mm
– Mandible 1mm
• Average linear OIIRR was 0.8mm with fixed
appliance using CBCT assessment (Samandra 2019)
• Usually apical than lateral is observed
Kennedy DB, Joondeph DR, Osterberg SK, Little RM. The effect of extraction and orthodontic treatment
on dentoalveolar support. American journal of orthodontics. 1983 Sep 1;84(3):183-90.
Linge BO, Linge L. Apical root resorption in upper anterior teeth. The European Journal of
Orthodontics. 1983 Aug 1;5(3):173-83.
Samandara A, Papageorgiou SN, Ioannidou-Marathiotou I, Kavvadia-Tsatala S, Papadopoulos MA.
Evaluation of orthodontically induced external root resorption following orthodontic treatment using
cone beam computed tomography (CBCT): a systematic review and meta-analysis. European Journal of
Orthodontics. 2019 Jan 23;41(1):67-79.

7. • 5mm or greater is considered as severe (Mirabella &
Artun 1995)
– 5% of adults
– 2% of adolescents (Linge &Linge 1983)
• Root resorption is virtually universal in patients who
had complete roots (Hendrix et al 1994)
• Patients with incomplete root formation did not
develop normal length roots, but these were still
longer than the older patients. (Hendrix et al 1994)
Mirabella AD, Årtun J. Prevalence and severity of apical root resorption of maxillary anterior teeth in
adult orthodontic patients. European journal of orthodontics. 1995 Apr 1;17(2):93-9.
Hendrix I, Carels C, Kuijpers-Jagtman AM, Hof MV. A radiographic study of posterior apical root
resorption in orthodontic patients. American Journal of Orthodontics and Dentofacial Orthopedics.
1994 Apr 1;105(4):345-9.

8. Types
• Brezniak & Wasserstein 1993
– Physiological- Resorption of primary teeth
– Inflammatory
– Replacement- ankylosis
– Idiopathic
• Andreasen et al 1987
– Apical
– Lateral
Andreasen FM, Sewerin I, Mandel U, Andreasen JO. Radiographic assessment of simulated root
resorption cavities. Dental Traumatology. 1987 Feb;3(1):21-7.

9. Mechanism of root resorption
• When orthodontic forces are applied, roots as well as
bone resorb. But cementum is repaired during periods
of quiscence. If repair doesn’t occur then permanent
loss of root structure occurs. (Brezniak & Wasserstein
1993)
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 1. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Jan 1;103(1):62-6
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 2. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Feb 1;103(2):138-46.

10. • Opinions are divided on causes of resorption.
– Theory I
• Mechanical trauma to apex- cell death- repair-if excess-
root resorption.
• PDL has protective effect because of fibroblast
presence, if areas of PDL have become hyalinised and
need removing before tooth movement can progress,
this is more likely with heavy orthodontic forces, the
protective effect of fibroblast would be lost.
– Theory II
• Possibly excess cementoclast and osteoclast activity.
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 1. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Jan 1;103(1):62-6
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 2. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Feb 1;103(2):138-46.

11. • Bone is resorbed in preference to cementum due to:
– Difference in collagen insertion- Dense insertion in
cementum so cementum surface not accessible by
osteoclasts/cementoclasts.
– Cementoid layer highly mineralised, less cellular activity.
– Might have anti invasion factors, against blood vessels
from developing (anti angiogenic factors ).
• Protection may come from innermost cellular layer of
PDL(due to fibroblast).
• Resorption occurs if osteoclasts access mineralised
root tissue via breach in covering cellular layer
Owman-Moll P, Kurol J, Lundgren D. Repair of orthodontically induced root resorption in
adolescents. The Angle Orthodontist. 1995 Dec;65(6):403-8.

12. • Repairs is greatest immediately after tooth movement.
• Irreversible once it extends into dentin
• Can happen quickly; 10- 35 days after appication of
force and usually before resorption lacunae is
apparent.
Owman-Moll P, Kurol J, Lundgren D. Repair of orthodontically induced root resorption in
adolescents. The Angle Orthodontist. 1995 Dec;65(6):403-8.

13. Grading of root resorption
• Levander &malmgren 1988
– Grade 1 - irregular root outline
– Grade 2 - <2mm root resorption (minor)
– Grade 3 - >2mm root resorption (severe)
– Grade 4 - >1/3rd of root length (extreme)
– Occasionally Grade 0 is added – no resorption.
Levander E, Malmgren O. Evaluation of the risk of root resorption during orthodontic treatment: a
study of upper incisors. The European Journal of Orthodontics. 1988 Feb 1;10(1):30-8.

15. • Kaley & Philips 1991
– Category 1 – slight blunting (mild)
– Category 2 – up to ¼ root length (moderate)
– Category 3 – over ¼ root length (severe)
• Profitt & Fields 2001
– Moderate generalized root resorption – seen in individuals
who have undergone comprehensive orthodontic treatment
– Severe generalised root resorption – rare
– Severe localized root resorption – often caused by
prolonged orthodontic treatment.
Kaley J, Phillips C. Factors related to root resorption in edgewise practice. The Angle Orthodontist.
1991 Jun;61(2):125-32.
Kundal S. An Insight into the Ubiquity of Root Resorption in Orthodontics-A Review. International
Journal of Dental Medicine. 2019;5(1):29-34.
Proffit WR, Fields Jr HW, Sarver DM. Contemporary orthodontics. Elsevier Health Sciences; 2006 Dec
8.

16. Etiology
• Complex and multifactorial
• Can be patient related and treatment related
(Weltman et al 2010).
Weltman B, Vig KW, Fields HW, Shanker S, Kaizar EE. Root resorption associated with orthodontic tooth
movement: a systematic review. American journal of orthodontics and dentofacial orthopedics. 2010
Apr 1;137(4):462-76.

17. Patient related risk factors
• Age
– Equivocal
– Some suggest treatment before completion of root
development , possibly the protective effect of pre-dentine.
(Brezniak &Wasserstein 2002; Linge & Linge 1983)
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 1. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Jan 1;103(1):62-6
Brezniak N, Wasserstein A. Root resorption after orthodontic treatment: Part 2. Literature review.
American Journal of Orthodontics and Dentofacial Orthopedics. 1993 Feb 1;103(2):138-46.
Linge BO, Linge L. Apical root resorption in upper anterior teeth. The European Journal of
Orthodontics. 1983 Aug 1;5(3):173-83.

18. • Gender
– Equivocal
– Some found higher in males, some in females. (Kjaer 1995;
Baumrind et al 1996)

19. • Ethnicity
– Hispanic>white>asian (Sameshima & Sinclair,
2001)

20. • Medical history
– Not strong association, but possible association
with asthma. (McNab et al 1999)
– Hypothyroidism / hypoparathyroidism – thyroxine
may have protective effect. (Shirazi et al 1999)

21. • Family history
– Siblings – heritability of 70% of resorption for
maxillary central incisor & lower molars. (Harris
et al 1997)

22. • Malocclusion
– Greater risk in class III, possibly due to compensated incisors
against the cortical plate. (Kaley and Philips 1991)
– Malocclusions with jiggling forces.
– Treatment of ectopic canines may get greater resorption of
maxillary lateral incisor & first premolars. This may be due to
the length of the treatment. (Woloshyn et al 1994)
– No risk factors related to increased overjet and overbite.
– Diminutive maxillary lateral incisors are more susceptible
(Kook et al 2003)

23. • Habits
– Bruxism, nail biting (odenrick & Brattstrom 1985)

24. • Tooth type & series
– 2>1>lower incisor>distal root of lower molar
(Weltman et al 2010)

25. • Root form/ shape
– It has been suggested blunt or pipette- shaped roots
or single rooted teeth are more prone to root
resorption. (Levander and Malmgren 1988)
– However meta analysis has found no association
between unusual root morphology and root
resorption (weltman et al 2010)

26. • Trauma
– Roots showing resorption due to previous trauma
have greater risk of further resorption, although no
greater risk if these teeth show no pre-treatment
resorption. (Malmgren et al 1982)
– Endodontically treated teeth have less resorption
provided RCT is sound. (Remington et al 1989;
Drysdale et al 1996)

27. • Drug related resorption
– The main drug employed for resorption is
bisphosphonates, which demonstrate a dose-
dependent reduction of root resorption when
administered in rats. (Adachi et al 1994; Igrashi et al
1996).
– Nabumetone, a drug belonging to NSAID group
reduces the amount of root resorption along with the
control of pain from intrusive orthodontic forces
without affecting the pace of tooth movement (Villa
et al 2005)

28. • Chronic alcoholism
– Chronic alcoholic receiving orthodontic treatment
are at a higher risk of developing severe root
resorption during the course of orthodontic
treatment. (Davidovitch et al 1996)

29. Treatment related risk factors
• Duration of treatment
– 2- phase vs 1- phase (class II) – less in phase 2
unless greater overjet reduction in phase 2 (Brin et
al 2003)
– Long treatment = great resorption (Roscoe et al
2015)

30. • Magnitude of force
– Heavy > light forces (Brudvik & Rygh 1994)
– Heavy forces show 12x increase in presence of
resorption craters when compared with control.
(Chan & Darendelier 2006)

31. • Type of tooth movement
– Intrusion 4x > extrusion (Han et al 2005)
– Intrusion force – 225 g(4x) > 25g(2x) > control
(Harris et al 2006)
– Rotation – greater resorption in medial 1/3rd .
(Jimenez-Pellegrin & Arana-Chavez. 2004)
– Torque – especially against cortical plate (Kaley &
Philips 1991)
– Continuous vs interrupted – no difference (Owman-
Moll et al 1995)

32. • Extraction patterns
– Extraction of 4 premolars > non-extraction
(Sameshima & Sinclair 2001)
– Extraction of 4s = non extraction.

33. • Archwire & Appliance
– Superelastic Niti > SS (Welland et al 2003)
– Archwire sequence – No difference (Mandall et al
2006)
– Class II traction/Rectangular archwires causes RR
– Self ligating = Conventional ligation

34. Diagnosis
• According to Brezniak & Wasserstein 1993,
radiographs are commonly used as diagnostic aids for
investigation of root resorption
• The techniques used include:
– Periapical bisecting angle
– Periapical paralleling
– OPG
– Cephalogram
– Laminogram
– CBCT

35. Prevention
• Dental history and examination
– Pre treatment warnings during consent
– Check for family history of resorption
– Review pre treatment root lengths; consider OPG
pretreatment radiographs
– Stop adverse habits
– Be wary of traumatised teeth (Alack 1999)

36. • Light forces
• Minimize treatment length
• Monitor progress:
• Radiographic evaluation 6/12 months into treatment,
however opinion is divided due to ALARA principle
• Start orthodontic treatment whilst young as pre
dentine gives a protective effect

37. • Reconsider treatment aims when resorption is
apparent.
• Consider 2-3 months break if resorption is identified.

38. Conclusion
• Root resorption is one of the most relevant problems
in orthodontics that does not have a clear cut method
of resolution or prevention
• We can use lighter forces and create an environment
that would minimize the chances of developing root
resorption.
• Utmost care and regular folow up are the only way to
reduce the adverse effects and achieve stable and
consistent results