19Arquivos em Odontologia • Volume 43 • Nº 01janeiro/março de 2007

Inhibition of Apical Root Resorption by CalciumHydroxide During Orthodontic Treatment: ACase Report

Inibição da Reabsorção Radicular Apical pelo Hidróxidode Cálcio Durante o Tratamento Ortodôntico: Relato deum Caso

Cinthia Mara da Fonseca Pacheco1, Daniela da Fonseca Pacheco1, 2, Patrícia Gonçalves da Motta1, 2

ABSTRACT

Apical root resorption is a common outcome of orthodontic treatment. The present article reports a case ofabsence of apical root resorption in a left maxillary lateral incisor filled with calcium hydroxide paste throughoutorthodontic movement. After orthodontic treatment was completed the tooth was subsequently obturatedwith gutta-percha and the patient followed for 18 months. The presence of a periapical lesion and theproperties of calcium hydroxide as a root resorption inhibitor were decisive for such an approach in thepresented case. Also, the role played by the vital dental pulp in the resorptive process was discussed.Key Words: Calcium hydroxide, apical root resorption, endodontic treatment, orthodontic treatment

INTRODUCTION

Periapical resorption of permanent incisors isan undesirable, but a common outcome oforthodontic treatment. Its incidence ranges from 19to 31.4% in all or some of the anterior teeth1. Studieshave shown that maxillary teeth are more severelyaffected than mandibular teeth, incisors are moreresorbed than canines within the arch, and the mostseverely resorbed teeth are maxillary lateralincisors, mainly because of the high incidence oftheir abnormal root shapes, which is been found tobe a significant factor in root resorption2.

Studies have demonstrated that differentdegrees of radiographic apical shortening occur onlyduring active orthodontic movement and ceasesafter ending of treatment3,4. In rare cases theresorption process may continues after active andretentive orthodontic treatment had beenterminated5.

1Master in Pharmacology, PhD student of Pharmacology Department ofFederal University of Minas Gerais, 2Private Endodontic Practice, Belo

Horizonte, MG, Brazil

It remains still challenging the reason why teethundergo periapical resorption after orthodontictreatment, and more intriguing, is the fact that duringorthodontic movement, endodontically treated teethappear to have less severe apical resorption thanvital ones6. It is known that the vital pulp plays akey role in the resorptive process releasinginflammatory mediators such as neuropeptides7.Therefore, lesser severity of periapical resorptionin endodontically treated teeth could be explainedby the removal of the blood supply and innervationsfrom the dental pulp, and consequently loss of thesemediators.

On the other hand, calcium hydroxide hasproved to be effective in preventing externalinflammatory root resorption, as demonstrated byseveral authors8, 9, 10. It is suggested that the role ofcalcium hydroxide in arresting root resorption, inaddition to its antibacterial effect, may depend onits alkaline pH, which makes osteoclastic andcementoclastic activity impossible11.

The purpose of the present article is to report acase of absence of apical root resorption in amaxillary lateral incisor filled with calciumhydroxide paste throughout the course oforthodontic movement.

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CASE REPORT

A 32-year-old white female came to the dentaloffice in order to have her maxillary left lateralincisor evaluated by an endodontist before shestarted orthodontic movement. A clinicalexamination showed a rotation of the referred tooth,tumefaction of the buccal mucosa near its apex,

tenderness to percussion, and no responsiveness toelectrical pulp testing. In a radiographicexamination, periapical radiolucency could beobserved (Figure 1-A). The diagnosis of the toothwas pulp necrosis. It was discussed with the patientthe possibility of a combined orthodontic-endodontic therapy.

Endodontic therapy was initiated on January9, 2002. After local anesthesia and rubber damisolation, the access preparation was made and theworking length established at 0.5 mm of theradiographic apex (Figure 1-B). The root canalpreparation was accomplished using 2.5% sodiumhypochlorite (Lenza Farm, Belo Horizonte, MG,Brazil) irrigation and hard instrumentation with K-type files (Dentsply, Ballalgues, Switzerland). Afterthe completion of the chemo-mechanical root canalpreparation, the root canal was dried with sterilepaper points and filled with calcium hydroxide(Lenza Farm, Belo Horizonte, MG, Brazil) with aK-type file. The access cavity was sealed with zincoxide eugenol cement (S.S. White, Rio de Janeiro,RJ, Brazil). By this time the orthodontist startedthe tooth movement.

Patient’s next appointment was rescheduled fora month later when a radiograph was taken. At thattime, the tooth was re-opened, a mildinstrumentation was performed and the root re-filledwith calcium hydroxide paste.

Next consult was on April 15, 2002. Anotherradiograph was taken in order to confirm thepresence of calcium hydroxide.

On May 5, 2002, calcium hydroxide dressingwas replaced and maintained for 3 months(Figure 1-C).

Subsequent appointments were scheduled with3 months intervals. At each consult, clinical andradiographic exams were performed, old calciumhydroxide paste removed and the root re-filled witha new one. These procedures were made during a14 months period.

On July 7, 2003 the patient finished herorthodontic treatment. After clinical andradiographic examinations, healing of periapicalregion was observed, which allowed the completionof endodontic treatment (Figures 1-D and 1-E).Briefly, the calcium hydroxide dressing wasremoved by irrigation with 2.5% sodiumhypochlorite. The root canal was then irrigated with17% ethylenediaminetraacetic acid (EDTA; LenzaFarm, Belo Horizonte, MG, Brazil) solution

21Arquivos em Odontologia • Volume 43 • Nº 01janeiro/março de 2007

followed by 2.5% sodium hypochlorite solution,dried with paper points and filled by lateralcondensation of gutta-percha points (Dentsply,Petrópolis, RJ, Brazil) and Endofill sealer (Herpo,Petrópolis, RJ, Brazil). Tooth was sealed with zincoxide eugenol cement and the patient referred to apractitioner to perform a definite restoration. Threemonths later, the patient returned for her firstevaluation (Figure 1-F).

On March 8, 2004 the patient returned foranother evaluation. The tooth remainedasymptomatic and a periapical radiograph revealeda healthy periapical region surrounding the leftlateral incisor (Figure 1-G). Moreover, absence ofapical root resorption of the endodontically treatedtooth could be observed.

The last evaluation of the patient was onJanuary 5, 2005. Radiographic examination did notshow any alteration since her last consult 10 monthsearlier (Figure 1-H). The patient was once moreadvised to seek for a definite restoration in this toothsince it was still filled with temporary cement.

DiscussionMany studies have shown an association

between root resorption and orthodontictreatment2,3,4. However, the mechanisms involvedin the resorptive processes are not well understood.

Several intriguing phenomena regarding apicalroot resorption can be observed. Firstly, vital teethexhibits more severe and frequently root resorptionthan endodontic treated ones. Also, radiographicobservations have shown that differences in healingbetween teeth that undergo orthodontic andendodontic treatment occur. Apical root resorptionthat follows pulp necrosis is usually followed, afterendodontic treatment, by a reconstitution of theoriginal resorbed root length with apical cementum.On the other hand, the apical resorbed rootfollowing orthodontic movement is neverreconstituted7. Actually, it is interesting to observethat in the presented case, such phenomena didoccur. In a first radiograph a periapical lesion couldbe observed in the lateral incisor as well as a slightresorption of its apical root. Eight months later, withthe healing of periapical region, a reestablishmentof root length could be seen. On the other hand, thevital teeth, central incisor and canine, did not showany recover of periapical root length after 18 monthsfollow-up since the resorption was caused byorthodontic movement.

Many explanations have been offered to thecause of the apical root resorption in vital teeth.The literature supports the fact that orthodontictooth movement can cause degenerative and/orinflammatory responses in the dental pulp withrelease of neurotransmitters such as substance P(SP) and calcitonin gene-related peptide (CGRP),which influence both blood flow and cellularmetabolism to the pulp/periapical region7. Theresulting increase in blood supply to these tissuesduring tooth movement impacts the availability ofcells of haematopoetic origin (osteoclast precursors)that are capable, under local stimulatory factors, todifferentiate into osteoclasts and influence theresorptive remodeling process of the teeth. Thesame activity may also occur with the cementoclastand therefore help to explain the apical resorption12.Also, histological observations of human periapicalroot tissue showed an increased cementum activityalong the inner root surface of the pulp in teethsubjected to orthodontic movement13.

As mentioned before, many studies havedescribed that endodontically treated teeth exhibitless propensity for apical root resorption duringorthodontic movement than vital teeth1,6. Inaddition, it has been shown that introducing calciumhydroxide into the apical region of the root canalcan enhance the arrest of resorption inendodontically treated teeth10,11. In the casepresented here it was chosen the therapy withtemporary calcium hydroxide dressing during thecourse of tooth movement rather than immediateobturation with gutta-percha points. One of thereasons for this approach is that calcium hydroxidepaste has proved to be efficient in preventing orinhibiting external inflammatory root resorption14,15.Also, if root resorption had occurred, even a minorone, extravasation of gutta-percha points, withcompromising of endodontic treatment, would hadhappened. Moreover, the main reason for the useof calcium hydroxide was that the tooth had anecrotic pulp and a periapical lesion. Although thereis a recent controversy about the necessity of anantimicrobial intracanal dressing in these cases16,it has been described the advantages of calciumhydroxide in favoring healing process of periapicallesions17.

In conclusion, this report showed that therapywith calcium hydroxide was able to inhibit the apicalroot resorption during orthodontic movement aswell as favored the healing of periapical region.

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RESUMO

A reabsorção radicular apical é umaconsequência comum do tratamento ortodôntico.O presente artigo relata um caso de ausência dereabsorção radicular apical em um incisivo lateralsuperior esquerdo preenchido com hidróxido decálcio durante a movimentação ortodôntica. Apóso término do tratamento ortodôntico, o dente foiobturado com gura-percha e o pacienteacompanhado por um período de 18 meses. Apresença de lesão periapical e as propriedades dohidróxido de cálcio como um inibidor de reabsorçãoradicular foram decisivas para tal conduta nopresente caso. O papel desempenhado pela polpadental nos processos de reabsorção radicular foitambém discutido.

Descritores: hidróxido de cálcio, reabsorçãoradicular apical, tratamento endodôntico,tratamento ortodôntico.

REFERENCES

1. Mattison GD, Delavanis HP, Delavanis PD, Johns PI.

Orthodontic root resorption of vital and

endodontically treated teeth. J Endod 1984; 10: 354-

358.

2. Sameshima GT, Sinclair PM. Predicting and

preventing root resorption: Part I. Diagnostic factors.

Am J Orthod Dentofacial Orthod 2001; 119: 505-

510.

3. Brezniak N, Wasserstein A. Root resorption after

orthodontic treatment: Part1. Literature review. Am

J Orthod 1993; 103: 62-66.

4. Killiany D. Root resorption caused by orthodontic

treatment: an evidence-based review of literature.

Semin Orthod 1999; 5:128-133.

5. Gholston LR, Mattison GD. An endodontic-

orthodontic technique for esthetic stabilization of

externally resorbed teeth. Am J Orthod 1983; 83:

435-440.

6. Spurrier SW, Hall SH, Joondeph DR, Shapiro PA,

Reidel RA. A comparison of apical root resorption

during orthodontic treatment in endodontically

treated and vital teeth. Am J Orthod Dentofacial

Orthod 1990; 97:130-134.

7. Bender IB, Byers MR, Mori K. Periapical replacement

resorption of permanent, vital, endodontically treated

incisors after orthodontic movement: report of two

cases. J Endod 1997; 23: 768-773.

8. Cvek M. Prognosis of luxated non-vital maxillary

incisors treated with calcium hydroxide and filled

with gutta-percha. A retrospective study. Endod Dent

Traumatol 1992; 8: 45-55.

9. Trope M, Moshonov J, Nissan R, Buxt P, Yesilsoy C.

Short vs. long-term calcium hydroxide treatment of

established inflammatory root resorption of replanted

dog teeth. J Endod 1992; 18: 492-496.

10. Hammarstrom LE, Blomlof LB, Feiglin B, Lindskog

SF. Effect of calcium hydroxide treatment on

periodontal repair and root resorption. Endod Dent

Traumatol 1986; 2: 184-189.

11. Tronstad L, Andreasen JO, Hasselgren G, Kristerson

L, Riis I. pH changes in dental tissues after root canal

filling with calcium hydroxide. J Endod 1981; 7: 17-

21.

12. Rygh P, Bowling K, Hoylandsdal L, Williams S.

Activation of the vascular system: a main mediator

of periodontal fiber remodeling in orthodontic tooth

movement. Am J Orthod 1986; 89: 453-468.

13. Bosshardt DD, Schroeder EE. How repair cementum

becomes attached to the resorbed roots of human

permanet teeth. Acta Anat 1994; 150: 253-266.

14. Cvek M. Prognosis of luxated non-vital maxillary

incisors treated with calcium hydroxide and filled

with gutta-perch. A retrospective study. Endod Dent

Traumatol 1992; 8: 45-55.

15. Tronstad L. Root resorption etiology, terminology

and clinical manifestations. Endod Dent Traumatol

1988; 4: 241-252.

16. Weiger R, Axmann-Kremar D, Löst C. Prognosis of

conventional root canal treatment reconsidered.

Endod Dent Traumatol 1998; 14:1-8.

17. Byström A, Happonen R-P, Sjögren U, Sundqvist G.

Healing of periapical lesions of pulpless teeth after

endodontic treatment with controlled asepsis. Endod

Dent Traumatol 1987; 3: 58-63.