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Year : 2021  |  Volume : 11  |  Issue : 2  |  Page : 266-270

Microguided endodontics: A case report of conservative approach for the management of calcified maxillary lateral incisors

Department of Conservative Dentistry and Endodontics, SRM Kattankulathur Dental College and Hospital, SRM Institute of Science and Technology, Chennai, Tamil Nadu, India

Date of Submission04-May-2020
Date of Decision24-Apr-2020
Date of Acceptance25-Jun-2020
Date of Web Publication8-May-2021

Correspondence Address:
Dr. Gurveen Kaur
House No. 3113, Sector 35-D, Chandigarh - 160 022
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sej.sej_102_20

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Pulp canal calcification due to dental trauma is described by hard-tissue deposition within the root canal space causing partial or complete obliteration and difficulty in locating canals. Endodontic treatment becomes difficult with increased risk for iatrogenic damage. Guided endodontics is a recent and an alternative solution in such cases. In this case report, a 28-year-old male patient reported with a chief complaint of pain in maxillary lateral incisors and a history of dental trauma that was diagnosed as pulpal necrosis with symptomatic apical periodontitis. The intraoral radiograph was taken, and apical radiolucency was confirmed with cone-beam computed tomography (CBCT) scan. A guided approach was decided for the location of the pulp canal with the use of microendodontic burs. A CBCT scan and an optical surface scan were performed and aligned using software for virtual template designing. The three-dimensional-printed template was positioned on to the tooth and with the help of microendodontic burs; the canal was located and biomechanically prepared using hand instruments. The root canal was obturated, and the cavity was sealed with a composite resin. This method demonstrated an ultraconservative, highly reliable, and successful treatment without the excessive removal of enamel and dentin.

Keywords: Apical periodontitis, microguided endodontics, pulp canal calcification, root canal treatment, template

How to cite this article:
Kaur G, Venkatesh KV, Sihivahanan D. Microguided endodontics: A case report of conservative approach for the management of calcified maxillary lateral incisors. Saudi Endod J 2021;11:266-70

How to cite this URL:
Kaur G, Venkatesh KV, Sihivahanan D. Microguided endodontics: A case report of conservative approach for the management of calcified maxillary lateral incisors. Saudi Endod J [serial online] 2021 [cited 2021 Jun 16];11:266-70. Available from: https://www.saudiendodj.com/text.asp?2021/11/2/266/315636

  Introduction Top

Pulp canal calcification also called as calcific metamorphosis occurs due to dental trauma undergoing subluxation and concussion injuries. It is distinguished from other traumatic injuries by yellowish discoloration of crown and deposition of hard tissue within the canal space.[1] Apart from traumatic injuries, tertiary dentin formation due to carious lesion or after restorative procedures may also cause narrowing of the pulp chamber.[2]

The mechanism of canal obliteration is not known, but it is believed to be associated with damage to the pulp neurovasculature at the time of injury.[3],[4] The yellowish discoloration, loss of translucency, and darker hue of the crown are due to calcification of the pulp chamber in young adults.[5]

Andreasen et al. observed that 15% permanent incisors which underwent trauma showed pulp canal obliteration, which was an indication of pulpal healing and therefore did not require any endodontic intervention.[6] However, if the pulp becomes necrotic, there is a higher risk of infection ranging from 7% to 27%.[1] The endodontic access and localization and negotiation of obliterated or calcified canals become exigent even with dental operating microscopes.[7] Not only the process is tedious but also can lead to iatrogenic errors causing root perforation and risk of instrument separation during cleaning and shaping of the root canals causing medicolegal cases.[8]

Thus, preoperative planning is recommended before the commencement of the treatment, and three-dimensional (3D) imaging may be an effective tool. Of late, a new technique known as “Guided Endodontics” has been introduced for the management of calcified canals with periapical pathology.[9] This approach plans the root canal treatment with the help of cone-beam computed tomographic (CBCT) scan to localize and negotiate obliterated root canals. The CBCT scan is merged with a 3D surface scan, and a template is manufactured to guide the treatment. The template can be fabricated with the help of a 3D printer guiding a minimally invasive drill to the calcified root canal. Buchgreitz et al. were the first to introduce this novel approach which was accurate enough to be used in vivo.[10]

Earlier studies used burs with diameter of 1.2–2.4 mm which are not suitable for the treatment of narrow root canals.[11],[12],[13] Therefore, the aim of this case report is to describe the use of guided endodontics in calcified maxillary lateral incisor using small diameter bur.

  Case Report Top

A 28-year-old male was referred to department of conservative dentistry and endodontics, with a chief complaint of dull throbbing pain in maxillary left lateral incisor (#22) for the past 1 month. Patient gave a history of dental trauma 10 years back. No clinically relevant medical history was evident for performing root canal treatment. During intraoral examination, the corresponding tooth was discolored [Figure 1]a and was tender on percussion. Thermal and electric pulp testing revealed negative responses. Radiographically, a completely obliterated pulp chamber and pulp canal was observed [Figure 1]b. The surrounding soft tissues were healthy with no swelling. The patient was symptomatic on biting and was diagnosed as pulpal necrosis with symptomatic apical periodontitis.
Figure 1: Clinical view showing yellow discoloration of maxillary left lateral incisor (#22) (a). Intraoral periapical radiograph of tooth #22 showing obliterated pulp chamber and pulp canal (b). Cone-beam computed tomography showing apical radiolucency and pulp canal calcifications. The root canal is visible in the apical part of the root (sagittal view) (c). Axial view of cone-beam computed tomography showing calcified pulp canal of 22 (arrow) (d). Virtual designing of the template showing guided pathway for the bur to the apical third of the canal (marked as x) (e). Cone-beam computed tomography scan showing the tooth of interest in green color (f). Superimposition of the designed template with the access point on the cone-beam computed tomography scan (g). Three-dimensional view of #22 showing the straight line access to the apex of the canal (h). Virtually designed template guide with bur for planned access cavity (i). Three-dimensional-printed template made with dental LT clear resin (j). Guiding of the bur through the template for straight line access to the apical third of the root canal (k). Minimally invasive access cavity preparation under dental operating microscope (l). Working length determination (m). Final radiograph with postendodontic restoration (n)

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For a complete 3D view of the periapical area and the complex anatomy of the root canal, a CBCT scan with high resolution and a limited field of view was taken. The CBCT (Carestream 9300; Carestream Health, Rochester, NY, USA) scan had a uniform thickness of 0.65 mm per slice and 84 kV, 6.0 mA exposure for 12 s. The CBCT images confirmed the presence of apical radiolucency and severely calcified pulp canal in 22 [Figure 1]c and [Figure 1]d. Root canal was visible 2.7 mm from the apex.

Guided endodontic approach for accessing the cavity preparation was decided due to the complex anatomy of the tooth. Miniature bur with a diameter of 0.6 mm, tip length of 8 mm, and a length of 28 mm (LN Bur, Dentsply/Maillefer) was used. For a virtual 3D scan, an impression was made using elastomeric putty material, and a gypsum dental model was prepared. The model was scanned using 3Shape (D900 Scanner; Holmens Kanal, Copenhagen, Denmark). Alignment of CBCT and scanned models was done and processed with Materialise Materialise Mimics software (version 20.0; Materialise NV, Leuven, Belgium).

A virtual copy of the bur was superimposed onto the scans which allowed access to the root canal till apical third of the tooth [Figure 1]e. The virtual bur position was checked for all three dimensions, and the template was designed by the inbuilt software tool to guide the drill clinically [Figure 1]f, [Figure 1]g, [Figure 1]h, [Figure 1]i. The template was converted into a Surface-Tessellation-Language format and was fabricated by a 3D printer (Formlabs Inc., Somerville, MA, USA). The guides were prepared using Dental LT Clear Resin (Formlabs Inc.) [Figure 1]j.

The exact fit of the template was checked intraorally on the patient. A position was marked on the enamel through the template which was the access point. A very minimal enamel was removed until dentin was exposed using a high-speed air rotor handpiece. Anterior teeth isolation was done using a rubber dam (Hygenic, Coltene Whaledent Inc., Akron, OH, USA) before starting the procedure. The template was placed on to the maxillary teeth. The bur was set to 10,000 rpm rotational speed to gain access to the root canal by pumping movements [Figure 1]k and [Figure 1]l.

Radiographs were taken to check accurate bur positioning, and further scouting of the canal was done using Gates Glidden drills Size 1 and 2 (Mani Inc., Japan). The patency of the root canal was checked using #10 K-file (Mani Inc., Japan). The working length was confirmed radiographically and with electronic apex locator (Root Z X2; J Morita Mfg Corp., Fushimi-ku, Kyoto, Japan) [Figure 1]m. The tooth was biomechanically prepared with step-back technique till #50 K-file apical enlargement and irrigated with 2.5% sodium hypochlorite and 17% EDTA. A calcium hydroxide dressing (RC Cal, Prime Dental, India) was placed followed by a temporary filling (Cavit™, 3 M ESPE) for 2 weeks. The tooth was asymptomatic, and obturation was performed with vertically condensed gutta-percha and an epoxy sealer (AH Plus, De Trey, Konstanz, Germany). The access cavity was cleaned and filled with a composite resin (Spectrum, Dentsply/Maillefer) using universal bonding agent (Prime & Bond, Dentsply/Maillefer) [Figure 1]n.

  Discussion Top

Endodontic treatment becomes a challenging task when a completely calcified canal along with apical periodontitis is observed. The current case report presented with calcified root canal with periapical radiolucency due to long-standing dental trauma. Due to the complexity of the case, a guided approach “3D template” was fabricated with the help of CBCT and intraoral scans for conservative access cavity.

In this case report, bur dimensions of 0.6 mm for access and biomechanical preparation with hand files were used for ultraconservative approach which is in support of studies done by Connert et al.[9],[14],[15] The smaller diameter of the bur caused less deviation from the straight line path of access and less heat production. However, with the smaller cross section of bur, the time required to gain canal patency was increased.

The virtual planning of microguided endodontics is very time-consuming, but the chairside time is minimal. Iatrogenic errors associated are reduced, thereby increasing the longevity and success of the treatment.[16] Cvek et al. stated that there is a high failure rate associated with conventional root canal treatment.[17]

However, there are few drawbacks associated with this method. It is not feasible in the posterior region due to increased space required for bur and template. It can only be used in cases with straight roots or straight part of curved roots. Hussey et al., in 1997, observed a rise in temperature when burs with larger diameter were used. Thus, the bur diameter should be small for less heat production on the root surface.[18]

Another limitation is the increased radiation dose of CBCT. Newer CBCT devices with low radiation dose (5 lSv) and small field of view can be used.[16] According to the European Society of Endodontology 2014, request of CBCT scan should be considered in case of complex anatomy of the tooth.[19]

Guided endodontics has become popular in managing calcified canals, tooth anomalies, dens evaginatus, normal tooth access preparation, and microsurgical procedures.[20],[21]

It requires a significant technical effort for planning the treatment. With the advent of intraoral scanners and CBCT along with rapid processing 3D printers, this technique may become a standard clinical procedure in the near future.

The use of intraoral scans aids in the accuracy of models. Optical scanners deliver a reliable copy of the teeth rapidly, which is vital in cases demanding high precision and sensitivity. In case, when there are no direct intraoral scanners present, this technique can still be performed. As in this presented case report, an impression with elastomeric impression material was made. The model so obtained was scanned through a laboratory optical scanner for template construction.

The back-and-forth pumping movement along with copious irrigation helped in gradual advancement of the drill and prevented microcracks and massive force onto the root walls.

Without the guidance, the operator has to take several radiographs and should be cautious enough to ensure the exact positioning of the instrument.[22] The number of intraoral radiographs is reduced and hence counterweighs the radiation dose received during CBCT scanning.[20] The periapical radiographs should be taken in at least two angulations to ensure the bur is not deviated from its path during the procedure.[23] The CBCT helps in evaluating the magnitude of calcification and provides accurate location, angle, and depth for negotiating the patent part of the root canal.[24]

An alternate option to guided endodontics is traditional root canal treatment and apical surgery. Experienced operators can perform conventional root canal treatment but factors such as risk of perforations, unnecessary tooth substance removal, and excessive radiation dose to the patient must be considered.[23] Apical surgery is an invasive and painful treatment for the patient. However, in severely curved root canals where straight line access is not achieved, it can be considered as the treatment of choice.[22]

  Conclusion Top

Minimally invasive access preparation was possible using the guided endodontic technique in a severely calcified pulp canal. This technique is valuable tool in locating complex root canal, reducing chairside time, and more significantly the risk of iatrogenic errors to the tooth structure.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published, and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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Fleig S, Attin T, Jungbluth H. Narrowing of the radicular pulp space in coronally restored teeth. Clin Oral Investig 2017;21:1251-7.  Back to cited text no. 2
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Robertson A, Lundgren T, Andreasen JO, Dietz W, Hoyer I, Norén JG. Pulp calcifications in traumatized primary incisors. A morphological and inductive analysis study. Eur J Oral Sci 1997;105:196-206.  Back to cited text no. 4
Patterson S, Mitchell D. Calcific metamorphosis of the dental pulp. Oral Surg Oral Med Oral Pathol 1965;20:94-101.  Back to cited text no. 5
Andreasen FM, Zhijie Y, Thomsen BL, Andersen PK. Occurrence of pulp canal obliteration after luxation injuries in the permanent dentition. Endod Dent Traumatol 1987;3:103-15.  Back to cited text no. 6
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Krastl G, Zehnder MS, Connert T, Weiger R, Kühl S. Guided endodontics: A novel treatment approach for teeth with pulp canal calcification and apical pathology. Dent Traumatology 2016;32:240-6.  Back to cited text no. 11
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Connert T, Zehnder MS, Amato M, Weiger R, Kühl S, Krastl G. Microguided endodontics: A method to achieve minimally invasive access cavity preparation and root canal location in mandibular incisors using a novel computer-guided technique. Int Endod J 2018;51:247-55.  Back to cited text no. 14
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Zitzmann NU, Krastl G, Hecker H, Walter C, Weiger R. Endodontics or implants? A review of decisive criteria and guidelines for single tooth restorations and full arch reconstructions. Int Endod J. 2009;42:757-74.  Back to cited text no. 16
Cvek M, Granath L, Lundberg M. Failures and healing in endodontically treated nonvital anterior teeth with posttraumatically reduced pulpal lumen. Acta Odontol Scand 1982;40:223-8.  Back to cited text no. 17
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