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Tooth resorption part II - external resorption: Case series.
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PMID:  23716975     Owner:  NLM     Status:  PubMed-not-MEDLINE    
External tooth resorption usually follows trauma to the periodontal ligament. It can be classified into five categories based on its clinical and histological manifestations. Calcium hydroxide has long been used as an intracanal medicament to slow down the resorption process due to its alkaline pH. A combination of both external and internal resorptions can also occur on the same tooth, making the management more complex. Five case reports of external resorption have been presented in this article along with pertinent review of literature. Successful management was possible in two cases, while extractions had to be advised in 3 cases due to advanced nature of the lesions.
Marina Fernandes; Ida de Ataide; Rahul Wagle
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of conservative dentistry : JCD     Volume:  16     ISSN:  0972-0707     ISO Abbreviation:  J Conserv Dent     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-05-29     Completed Date:  2013-05-30     Revised Date:  2013-05-31    
Medline Journal Info:
Nlm Unique ID:  101147009     Medline TA:  J Conserv Dent     Country:  India    
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Languages:  eng     Pagination:  180-5     Citation Subset:  -    
Department of Conservative Dentistry and Endodontics, Goa Dental College & Hospital, Bambolim, Goa, India.
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Journal Information
Journal ID (nlm-ta): J Conserv Dent
Journal ID (iso-abbrev): J Conserv Dent
Journal ID (publisher-id): JCD
ISSN: 0972-0707
ISSN: 0974-5203
Publisher: Medknow Publications & Media Pvt Ltd, India
Article Information
Copyright: © Journal of Conservative Dentistry
Received Day: 27 Month: 5 Year: 2012
Revision Received Day: 15 Month: 6 Year: 2012
Accepted Day: 23 Month: 7 Year: 2012
Print publication date: Season: Mar-Apr Year: 2013
Volume: 16 Issue: 2
First Page: 180 Last Page: 185
PubMed Id: 23716975
ID: 3659868
Publisher Id: JCD-16-180
DOI: 10.4103/0972-0707.108216

Tooth resorption part II - external resorption: Case series
Marina Fernandesaff1
Ida de Ataideaff1
Rahul Wagle1
Department of Conservative Dentistry and Endodontics, Goa Dental College & Hospital, Bambolim, Goa, India
1Consulting Endodontist, Goa Dental College & Hospital, Bambolim, Goa, India
Correspondence: Address for correspondence: Dr. Marina Fernandes, Department of Conservative Dentistry and Endodontics, Goa Dental College and Hospital, Bambolim, Goa, India. E-mail:


External resorption is initiated in the periodontium and affects the external or lateral surfaces of a tooth. It is a common sequelae following traumatic injuries, orthodontic tooth movement, or chronic infections of the periodontal structures. It can occur as a single entity or a combination of internal and external resorptions can occur simultaneously on the same tooth and they may appear as separate or joined defects.[1] External resorption is often confused with internal resorption. The difference between internal and external resorption is described previously.[2]

External resorption is further classified into external surface resorption, external inflammatory resorption, external replacement resorption, external cervical resorption, and transient apical breakdown.[1, 3]

External surface resorption

This type of resorption is self-limiting in nature and usually occurs following trauma. It manifests itself as small superficial lacunae in the cementum and may extend in the outermost layer of dentin. These excavations are sometimes seen on the radiograph as small irregularities on the root surface with normal lamina dura and periodontal space.[1, 46]

External inflammatory resorption
Case 1

A 20-year-old female patient undergoing orthodontic treatment was referred for the management of external resorption in teeth # 20, 21, apparent on the periapical radiograph. The patient was asymptomatic and the medical history was non-contributory. Past dental history revealed extraction of an impacted tooth that was present between the apices of teeth # 20 and 21, about 1 month earlier. Clinically, the teeth were noncarious and appeared normal. They responded to both thermal and electric pulp testing within normal limits. The apices of teeth # 20 and 21 showed irregular margins with loss of adjacent lamina dura on a periapical radiograph. A circular radiolucency was present in between the root apices that probably represented the space that was occupied by the crypt of the impacted tooth [Figure 1a].

Since the patient was undergoing orthodontic treatment, all active forces were removed. Following access cavity preparations, the vital pulp tissue was extirpated and thorough debridement of the canal system was done to the working length with hand stainless-steel K-files upto size 45. The profuse bleeding from the canal especially on reaching the apical region was controlled with copious irrigation of 5.25% NaOCl. The canals were dried with paper points and Ca(OH)2 paste was placed in the canals as an intracanal medicament. The medicament was changed after every 15 days. Periodic radiographs were taken after every 1 month [Figure 1bd]. Orthodontic treatment was resumed after 3 months from the commencing of treatment as radiographic signs of healing were evident. Ca(OH)2therapy was continued for a period of 2 months further at the end of which complete periapical healing and normal root architecture of the root apices was evident [Figure 1e]. Root canal obturation of both the teeth was then completed and a follow-up radiograph after 1 year shows maintenance of the restored root architecture [Figure 1f].

External inflammatory resorption usually follows trauma or periodontal infections that can initiate an inflammatory response within the periodontal ligament.[4, 5] It could be a squeal to pressure induced by the crypt of an erupting/unerupted tooth, neoplasms or during orthodontic treatment.[5] Excessive intrusive or tipping orthodontic forces can initiate an inflammatory response.[7] In the above case, the pressure induced by the crypt of the impacted tooth coupled with the orthodontic treatment could have been the etiologic factors leading to resorption. External inflammatory root resorption usually occurs without any clinical symptoms and forms part of the periapical pathology associated with apical periodontitis.[8] Placement of Ca(OH)2 intracanal medicament has been recommended for 6 to 24 months. It exerts an antibacterial effect and also increases the pH of dentin by the diffusion of hydroxyl ions through the dentinal tubules.[9] It also induces the formation of a new cemental apical barrier thus preventing over-extension of the root filling material.[10]

External replacement resorption
Case 2

A 19-year-old female patient presented to the department with a chief complaint of discoloured anterior teeth. The patient had completed her orthodontic treatment about 1 year back and had also undergone an orthognathic surgical procedure. On clinical examination, teeth # 7, 8, 9 and 10 displayed a yellowish brown discoloration. Grade I mobility was evident in teeth # 7 and 10 and grade II mobility in teeth 8 and 9. On percussion teeth #8 and 9 gave a typical metallic sound as compared to adjacent teeth. An unsuccessful attempt at access cavity preparation was detected on the palatal aspect of tooth #9. Teeth #8 and 9 failed to respond to thermal and electric pulp testing while teeth #7 and 10 responded within normal limits. A periapical radiograph revealed severe replacement of root structure of teeth #8 and 9 with alveolar bone with only half the root lengths persisting [Figure 2]. Some amount of root replacement was also seen in teeth #7 and 10. No canal spaces were evident in teeth #8 and 9; hence, no attempt was made to initiate any treatment. It was planned to take periodic periapical radiographs to assess the progression of replacement resorption in teeth #7 and 10. The patient was explained the poor prognosis but at the same time was reassured that there was no exigency in extracting the teeth. Composite laminate restorations were done for teeth #7, 8, 9 and 10 to mask the discoloration. A follow-up after 1 year revealed no significant increase in teeth mobility and resorption rate.

External apical root resorption is commonly associated with orthodontic therapy due to certain biological factors (genetic susceptibility, systemic diseases associated with phosphorous-calcium metabolic alterations, medication intake) and mechanical factors (tooth movement type, orthodontic force magnitude, duration and type of force).[11, 12] Hence, it is essential to take periodic periapical radiographs during treatment.[13] When root resorption is detected during active treatment, a decision must be made as to whether to continue, modify or discontinue the treatment.[12] Luxation injuries are reported as the principal cause of replacement resorption.[14] In this case orthodontic therapy was probably the etiologic agent which also initiated calcific metamorphosis in teeth #8 and 9. Replacement resorption is a continuous process whereby the tooth is gradually replaced by bone.[1] Teeth undergoing this form of resorption, have a characteristic metallic percussion sound[1, 15] as was observed in this case. There is no known treatment for this type of resorption[5, 16] though unsuccessful attempts at Ca(OH)2therapy to arrest the resorption have been tried.[4] If the teeth are in a satisfactory position, there is no urgency for tooth replacement because the replacement usually progresses at a slow rate ranging from few months to years. This provides time for the patient to be mentally and financially prepared for the treatment planned by the clinician.[5]

External cervical resorption

External cervical resorption is a complex pathologic condition that challenges the clinician because of its infiltrative nature in the later stages of its development.[17] Several etiologic factors may initiate external cervical resorption like dental trauma, orthodontic treatment, periodontal therapy, intracoronal bleaching.[15, 1822] Clinically a pink spot is usually seen in the cervical region which is the result of highly vascular granulation tissue within the tooth which becomes visible through the thinned out dentin and translucent overlying enamel.[3] A clinical classification (4 classes) that describes extend of penetration of the resorptive lesion has been developed by Heithersay as a guideline for treatment planning.[18] Class 1-Denotes a small invasive resorptive lesion near the cervical area with shallow penetration into dentine. Class 2-Denotes a well-defined invasive resorptive lesion that has penetrated close to the coronal pulp chamber but shows little or no extension into the radicular dentine. Class 3-Denotes a deeper invasion of dentine by resorbing tissue, not only involving the coronal dentine but also extending into the coronal third of the root. Class 4-Denotes a large invasive resorptive process that has extended beyond the coronal third of the root. Schwartz et al.[23] recommended three choices of treatment when external cervical resorption is diagnosed: 1. No treatment with eventual extraction when the tooth becomes symptomatic; 2. Immediate extraction; or 3. Access, debridement, and restoration of the resorptive lesion. Usually option 1 and 2 are advised for class 3 and 4 lesions,[23] whereas for class 1 and 2 lesions topical application of 90% trichloroacetic acid followed by debridement and restoration is usually successful.[17, 24] Successful management of class 3 lesions have also been reported.[23, 24]

Case 3

A 12-year-old female patient was referred by a private practitioner who detected a mass of soft tissue on the palatal aspect of tooth 11. The patient had a history of alveolar cleft repair done about 1 year back. Clinical examination revealed an extensive soft tissue mass in a palatal defect of tooth 11 [Figure 3a]. Gentle exploration revealed that besides loss of the palatal enamel there was also loss of enamel from the interproximal areas of the tooth. However, the labial surface of the tooth was intact. The tooth responded to thermal and electric pulp testing within normal limits. A periapical radiograph revealed a large irregular radiolucency in the coronal region of the tooth extending mesiodistally and slightly into the coronal radicular dentin [Figure 3b]. A diagnosis of Class 2 external cervical resorption was made.

Glycerol was applied to the adjacent tissues to form a protective film. Isolation was achieved using the cuff rubber dam technique. A small cotton pellet was then dipped in 90 percent trichloroacetic acid and the excess was removed by dabbing it on a piece of gauze. The cotton pellet was then applied over the resorptive tissue mass with gentle pressure for about 1 minute. The tissue mass underwent necrosis with repeated application of trichloroacetic acid which was curetted out till a sound dentinal base was revealed [Figure 3c]. Care was taken to see that the interproximal areas of the tooth were thoroughly debrided. The cavity was then refreshed with a high speed bur and restored with glass ionomer cement [Figure 3d].

Trichloroacetic acid is a chemical escharotic agent that causes coagulation necrosis and renders the resorptive tissue avascular.[5] The use of trichloroacetic acid does not necessitate raising a flap to gain access to the lesion. This eliminates the possibility of active resorbing cells present in the flap from being repositioned over the repaired root surface.[17] However, due to the caustic nature of the acid, certain guidelines need to be followed as outlined by Heithersay:[17, 24] a. The adjacent soft tissues should be protected with glycerol, b. A thin glycerol impregnated cotton roll should be placed into the gingival sulcus for added protection, c. The cuff rubber dam technique should be employed to prevent slippage of the acid impregnated cotton pellets into the oral cavity, d. Very small cotton pellets or mini applicators must be used and excess solution should be dampened on gauze, e. Tweezers used to carry the cotton pellets must not be used for other purposes during the procedure.

A reduction of the microhardness in both dentin and enamel has been reported following the use of trichloroacetic acid.[25] Hence, restorations that will reinforce the weakened tooth structure are recommended. Chemical adhesion to tooth structure favours glass ionomer cement as the restorative material of choice.[26] Recently a ‘reverse sandwich restoration’ comprising of microfilled resin composite and resin modified glass ionomer cement has been proposed to overcome the hydrolytic instability of glass ionomer cement. The microfilled resin tends to flex with the tooth thus reducing the chances of debonding.[27]

Trichloroacetic acid etches dentin and enamel and hence, conditioning is not recommended prior to insertion of the glass ionomer cement.[25] However, refreshing the tooth surface with a bur is necessary because dentin that has been treated with trichloroacetic acid is severely demineralised and is not suitable for bonding with either dentin-bonding agents or glass ionomer materials.[23]

Case 4

A 23- year-old female patient with a non contributory medical history expressed her desire to close the spaces between her anterior teeth. Past dental history revealed a history of trauma about 8 years back. Clinical examination revealed a 5 mm diastema between teeth #8 and 9. Tooth #9 and 10 displayed a pinkish hue in the cervical third of the crowns. Tooth #10 displayed grade II mobility while tooth #9 was non mobile. A ‘catch’ with the explorer was detected in mesial cervical region of tooth #9. A periapical radiograph revealed a large resorptive lesion in tooth #9 extending from the cervical region to almost the apical third of the root. The periodontal ligament space (PDL) space could not be traced suggestive of ankylosis. Tooth #10 showed an infiltrative kind of radiolucency extending from cervical to apical third of the root [Figure 4]. Both the resorptive lesions were classified as class 4 lesions according to Heithersay's classification[18] and due to poor prognosis, extraction was advised for both teeth #9 and 10.

Case 5

A 16-year-old female patient reported to the department with a chief complaint of discolored tooth #9. Past dental history revealed that the tooth was avulsed about 10 years back and was immediately replanted by the patient's father. On clinical examination, the clinical crown height of tooth #9 was much lesser than the adjacent teeth and the cervical portion of the crown displayed a pinkish hue. A perforation was detected in the cervical third of the crown on the palatal aspect with an endodontic explorer and was seen extending mesially and distally. Profuse bleeding was evident on exploration. On the periapical radiograph, tooth #9 had the appearance of an immature apex with thin incompletely developed parallel root canal walls. The pulp canal space was obliterated by a less radio opaque material resembling bone which appeared to be in continuity with the periapical bone. A large ill defined radioluency was seen in the cervical third of the crown extending extensively in a mesiodistal direction [Figure 5]. Computerized tomography (CT) scan slices revealed the canal configuration of the tooth at the coronal, middle and apical levels. At the coronal level a break in the continuity of the palatal wall was observed that was indicative of a perforation. The canal space showed radio opacity resembling bone [Figure 6ac]. At the middle third of the root, CT slices displayed a continuity of the canal walls [Figure 6de] and slices in the apical region revealed thin mesial and distal canal walls [Figure 6f].

Following replantation of avulsed immature teeth, in growth of periodontal tissues into the canal space has been observed as an attempt at revascularization. It has been reported that well organized bone, PDL and cementum can grow into the canal space.[28] In this case tooth #9 which been replanted had a wide open apex which probably provided an open pathway for the in growth of periodontal tissues following damage to the pulp. The pulpal tissue was replaced by metaplastic bone like tissue that was evident on the radiograph and the CT scan images. The perforation that was present in the cervical third of the crown on the palatal aspect and the presence of granulation tissue indicated it to be a case of external cervical resorption. Though the radiographic appearance also resembles perforating internal resorption, this diagnosis could be ruled out due to the absence of vital apical pulp tissue which is essential for internal resorption to progress. The presence of a weakened coronal tooth structure due to the extensive nature of the resorption process and the obliteration of the canal space with metaplastic bone like tissue signalled a poor prognosis for the tooth which was hence advised an extraction.

Transient apical breakdown

This is reported as a temporary phenomenon in which the apex of the tooth displays the radiographic appearance of resorption following trauma and generally returns to normal following repair in a period of 1 year. The teeth respond normally to pulp tests and radiographically a widening of the PDL space and blunting of apices may be seen. No treatment is recommended as this an ephemeral type of resorption.[1, 29]


Tooth resorption is a pathologic condition that still remains a mystery in many aspects. It may go unnoticed over many years as most cases of resorption are asymptomatic in nature. Early detection of resorption is essential for successful management. Besides clinical examination and periapical radiographs, several studies have confirmed the usefulness of cone beam computed tomography (CBCT) in the diagnosis of resorption.[30, 31] More studies are warranted in understanding the resorption process in order to device newer and more predictable treatment approaches.


Source of Support: Nil

Conflict of Interest: None declared

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[Figure ID: F1]
Figure 1 

(a) External root resorption in teeth #20 and 21 of a 20-year-old female patient, (b-d) Repair of root architecture and healing of periapical radiolucency following placement of calcium hydroxide paste after 1, 2 and 3 months respectively, (e) Complete periapical healing and repair of root architecture after 5 months, (f) 1 year follow-up radiograph shows maintenance of the restored root architecture

[Figure ID: F2]
Figure 2 

External replacement resorption in teeth #7, 8, 9 and 10 of a 19-year-old female patient following orthodontic therapy

[Figure ID: F3]
Figure 3 

(a) A soft tissue mass in a defect on the palatal aspect of tooth #8 of a 12-year-old female patient, (b) A large irregular radiolucency in the coronal region of the tooth extending mesiodistally and slightly into the coronal radicular dentin, (c) A sound dentinal base evident after removal of resorptive tissue, (d) Restoration of cavity with glass ionomer cement

[Figure ID: F4]
Figure 4 

External cervical resorption in teeth #9 and 10 of a 23-year-old female patient following trauma

[Figure ID: F5]
Figure 5 

Tooth #9 of a 16-year-old female patient displaying an immature apex with thin incompletely developed parallel root canal walls. Metaplastic bone like tissue seen obliterating the canal space. An ill-defined radiolucency in the coronal portion of the tooth was diagnosed as external cervical resorption

[Figure ID: F6]
Figure 6 

Computerized tomography (CT) scan slices showing the canal configuration of the tooth #9 at the coronal (a, b, c), middle (d, e) and apical levels (f). (a) Continuous canal walls with a wide pulp space, (b) Break in the continuity of the palatal wall distally, (c) Complete discontinuity of the palatal wall representing the resorptive site, (d) (e) Re-establishment of the canal continuity, (f) Thin distal and mesial canal walls evident which can be correlated with the radiograph

Article Categories:
  • Case Report

Keywords: Calcium hydroxide, external root resorption, osteoclast, resorption, trichloroacetic acid.

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