Effective
Endodontically Treated Incisors with External Root Resorption during
Orthodontic Movement: A Case Report
Abstract
This case report describes a 21-year-old orthodontic patient experienced
the external apical root resorption of maxillary central incisors with
pulpitis during the orthodontic movement. The active cooperation of
orthodontists and endodontists demonstrated the satisfactory treatment
outcome and prevention of further apical root resorption. The etiology
of external apical root resorption is comprehensive, orthodontists
should be armed with an adequate training and scientific knowledge, and
keep the treatment mechanism simple and precise to guard against it.
Besides, we should know the right timing of endodontic treatment and
applying orthodontic force when external apical root resorption occurs.
1 Introduction
External apical root resorption(EARR) is one of the most undesirable
sequel of orthodontic treatment, which was first reported by Ottolengui
in 1914.[1] EARR may occur in as many as 90% of orthodontically
treated patients[2] ,and it is most commonly seen in the maxillary
incisors.[3][4] EARR associated with orthodontic forces is
typically root surface resorption and causing the apical region of the
roots to become shorter, even cause an imbalanced ratio of crown and
root in the affected teeth.
While, orthodontically induced EARR can be considered as a frequent and
acceptable complication. Orthodontic treatment itself does not induce
the pulp necrosis nor calcific metamorphosis of the pulp. Moreover, the
pulp is vital in teeth with EARR induced by orthodontic treatment.
Endodontic treatment is not required unless pulp symptoms
involved.[5] Root canal treatment can be considered for preventing
EARR for severe externa root apical resorption.[2] Endodontically
treated teeth may have a lower level of EARR even the difference might
not be clinically significant (up to 1mm).[6]
This case report describes a 21-year-old girl undergoing orthodontic
treatment encountered pulpitis and external apical root resorption of
maxillary central incisors. When pulp symptoms appear, orthodontists
consulted with the endodontist in time to complete endodontic treatment.
Timely
and effective endodontic treatment not only controlled the external
apical root resorption, but also ensured orthodontic treatment proceeded
smoothly.
2 Diagnosis and etiology
A girl aged 21 years old asked for orthodontic treatment with the chief
complaints of irregularly located teeth and protrusion. Facial
photographs showed mild asymmetry, with the left side larger than the
right. The lateral view showed a slight convex facial profile with upper
and lower lips to the E-line measurements of 0.9mm and 0.7mm,
respectively. Intraorally, deep bite with excessive eruption of
mandibular incisors, the maxillary dental midline was shifted to the
right by 1mm, and the mandibular dental midline was shifted to the left
by 1mm. The maxillary right canine buccally erupted, the mandibular
second premolar inclined buccally and crossbite. An Angle Class I molar
relationships were seen on both sides. Mild gingivitis and
Teeth
#11, #36, #46, #47 were caries (Fig1).Cast analysis showed severe
crowding in both maxillary and mandibular arch(Fig2). The panoramic
radiograph showed four wisdom teeth and asymmetric morphology of
bilateral condyles. No TMJ symptoms and signs were noted. Cephalometric
radiograph revealed a skeletal Class I relationship (ANB, 1.59) and low
Mandibular plane angle (SN-MP, 24.26)(Fig 3; Table1). The diagnosis of
this present patient was skeletal Class I malocclusion, low mandibular
plane angle, and Class I dental relationships.
3 Treatment objectives
Caries were asked to go for dental treatment. Better oral hygiene was
required. Because of the severe crowding and convex facial profile, the
patient’s 4 first premolars were planned for extraction to relieve the
crowding and improve the profile. 4 third molars were also planned for
removal. Align maxillary canine and mandibular premolar, correct their
inclination, correct anterior deep bite by controlling lower incisor
eruption to establish normal bite. Moderate anchorage was planned to
achieve ideal occlusal relationship with coinciding upper and lower
midline. Improve facial and dental appearance by orthodontic treatment.
4 Treatment progress
Completing resin fillings of teeth#11, #36, #46, #47 and removal of
the 4 first premolars, the maxillary and mandible arch were bonded with
0.022-inpassive self-ligation system( Damon Q; Ormco, Glendora, Calif).
The following sequence of arch wires was used for leveling and
alignment:(1) 0.014 NiTi (Both arches), (2) 0.016 NiTi (Both arches),
(3) 16 x 22 NiTi (Both arches),(4) 18 x 25 NiTi (Both arches), (5) 19 x
25 NiTi (Both arches), (6) 19 x 25 SS (Both arches), and (7) 0.014 SS
(Both arches) with settling elastics.
However, the patient complained of maxillary right incisor pain and
swelling one year after the start of orthodontic treatment. We paused
the orthodontic process and referred to the endodontist for further
examination. Clinical dental examination revealed the apical sinus tract
of tooth #11, electronic pulp vitality test respond negative with
grade-one mobility based on Millers Mobility Index. Periapical
radiographs showed decreased apical density of two maxillary central
incisors. The ratio of root and crown length decreased to 1.29(tooth
#11) and 1.12(tooth#21) from the initial 1.47 respectively(Fig4A).
Crown and root lengths were measured using the method of Linge.[7]
Repeated electronic pulp test of #21 showed vital. Based on the above
examination results and analysis, #11was diagnosed with periapical
periodontitis, and undergone root canal treatment immediately. Due to
the pulp is vital and no clinical symptoms, tooth #21 was not
endodontically treated for the time.(Fig4B)
Unfortunately, tooth #21 occurred apical sinus tract and no vitality of
electronic pulp test 2-month later. Periapical radiographs displayed
decreased apical density and further EARR of tooth #21, the ratio of
root and crown length decreased to1.10(Fig4C). Diagnosis of tooth #21
was chronic periapical periodontitis, and underwent root canal
treatment. A three-month follow-up showed the reducing
density-decreasing area, and no progress of EARR(Fig4D). The sinus tract
has completely healed and no clinical symptoms.
Orthodontic treatment was continued 6 months after root canal treatment.
During the latter orthodontic treatment, maxillary central incisors had
no progress of EARR. The total treatment duration was 33 months,
including a 8-month interval for dental treatment.
5 Treatment results
Post-treatment exhibited acceptable and appreciable outcome with
improved profile. The Class I molar relationship on both sides was
maintained throughout the treatment. The canine relationships were
corrected to Class I, and the upper, lower, and facial midlines were
coincident(Fig5,Fig6). A functional occlusion was established with
stable posterior support and proper anterior guidance. The
superimposition of the cephalometric tracings before and after treatment
showed the treatment goals were achieved(Fig7). 3 year post-treatment
revealed proper retention and stability(Fig8). There was no complaint of
discomfort in the affected teeth, the clinical examination was normal,
the dental function was good, and the occlusal relationships and
function remained stable. Radiographs showed continuous intact
periodical membrane, no change in alveolar bone height, no further root
resorption, no change in root length(Fig4E). Two third molars will be
extracted.
6 Discussion
The etiology of EARR is comprehensive, including individual biological
characteristics,
genetic
predisposition and the effect of orthodontic forces. Risk factors can be
divided into patient-related and treatment-related factors.[8] The
orthodontic treatment duration, magnitude of applied force, direction of
tooth movement, amount of apical displacement, and method of force
application are all belong to the latter.[9] Levander et al and
Kjaer reported a higher prevalence of EARR in females than
males.[10][11] The prolonged treatment duration and treatment
with extraction are the highly related risk factors.[6] Besides, the
use of class II elastics could aggravated root resorption of
incisors.[7]
In this case, we used the conventional light force for leveling and
alignment, applied short-time class II elastics for later occlusal
adjustment. The cause of necrotic pulp may be attributed to
patient-related factors. It probably due to the dental caries secondary
to periodontal inflammation for tooth #11.The cause of tooth#21 EARR
was not very clear, and it might owe to periapical inflammation or
patient’s tolerance. During orthodontic treatment, the incidence rate of
external apical root resorption is up to 90%. Pulp infections and
periapical inflammation can increase the incidence of external apical
root resorption. Kaku[12]proved that orthodontic treatment may
promote the expression of inflammatory factors in the pulp tissue.
During orthodontic movement, an aseptic inflammatory process which
consisting of excessive force, inflammatory cells, the surrounding
matrix, bones, and biological messengers will
occur.[13][14]Therefore,
the status of the pulp should be determined before orthodontic
treatment.
In this case, tooth #11 had caries and tooth# 21 had no caries before
orthodontic treatment. Undergoing 1 year of orthodontic treatment,
tooth#11occured necrotic earlier than tooth# 21, and X-ray examination
showed the tooth #11 had EARR and periapical lesions. It was proved
that the pulp inflammation aggravated the degree of EARR. Root canal
treatment can remove the infected pulp tissue and stop the periapical
inflammation during the force application. In our case, no further
development of EARR was found in the follow-up after treatment of
tooth#11 and tooth#21.
When it comes to the timing of RCT, both of the pulp status and the
severity of EARR should be considered together. Ballal’s [15]case
published in 2008 suggested that loss of pulp vitality does not always
occurred with the external apical root resorption. Endodontic treatment
is recommended only when pulp necrosis with periapical inflammation or
severe apical root resorption. Root length reduction is more than 4mm or
1/3 of original root length is considered the severe apical root
resorption. We should distinguish the etiology of the moderate and
severe root resorption according to Proffit[16]. In the case of
extreme resorption, endodontic treatment should be taken even the pulp
is vital. Severe root resorption, such as the root length less than 9mm,
will affect the prognosis of the teeth[17].
In this case, one year after the start of orthodontic treatment,
tooth#11 showed no vitality while 21 showed vitality. When both tooth
showed obvious external apical root resorption on X-ray examination,
endodontists did RCT only for tooth#11. RCT for tooth #21 was
performed 2 months later when pulp showed no vital. Therefore, RCT is
not recommended for teeth without pulp symptoms. We did RCT for the
affected incisors to remove the infective agents, and stopped applying
the orthodontic force. Armans[17] proposed a same point in the case
published in 2008.
Since the orthodontic treatment will not affect the outcome of RCT, it
can only delay the healing process. When to start applying orthodontic
force should be considered. De Souza[18]established a model of
periapical periodontitis in dog’s teeth, and suggested 3 weeks after
RCT. For teeth with large periapical lesions, the orthodontic treatment
should be initiated at least 3months later. Still, it is recommended to
take X-ray examination every 3 months during orthodontic treatment to
follow up the healing process. We reapplied orthodontic force 6 months
later in our case.
Satisfactory endodontically treated teeth had more resistance to the
applied orthodontic forces than pulp vitality, and consequently being
moved safely with less resorption. [13][14] [19][20]The
endodontic treatment in our case could be called successful for strongly
tolerating the orthodontic forces along with the physiologic masticatory
forces. Furthermore, EARR never aggravated during following treatment
and retention period.
Since EARR is a multifactorial phenomenon, care should be taken to
prevent it by keeping the orthodontic treatment mechanism simple and
precise.
For
patients who have notable root resorption, follow-up radiographic
examinations are recommended until root resorption is no longer evident.
7 Conclusion
Orthodontists should be mindful that multiple factors lead to EARR, and
have an adequate training and scientific knowledge to adopt preventive
and predictive approaches to EARR in orthodontic
practice.
Effective endodontic treatment makes EARR teeth safer for orthodontic
movement.
8 Conflict statement
All authors have no conflict of interest.
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