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 Table of Contents  
Year : 2022  |  Volume : 34  |  Issue : 2  |  Page : 131-136

Guided endodontics: Management of calcified tooth with a large periapical lesion using cone beam computed tomography and three-dimensional printed guide: A case report

Department of Conservative Dentistry and Endodontics, Annoor Dental College, Muvattupuzha, Kerala, India

Date of Submission26-Mar-2021
Date of Decision30-Nov-2021
Date of Acceptance01-Mar-2022
Date of Web Publication01-Jul-2022

Correspondence Address:
Dr. Anciya Mohamed Nazar
Department of Conservative Dentistry and Endodontics, Annoor Dental College, Puthuppady P.O, Perumattom, Muvattupuzha - 686 673, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/endo.endo_84_21

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The aim of this case report is to depict novel guided endodontic approach for the management of calcified tooth with a large periapical lesion using cone beam computed tomography (CBCT) and three-dimensional (3D) printed guide. The patient presented with swelling on the upper left front tooth region. Intraoral periapical radiograph revealed periapical radiolucency associated with upper left lateral incisor. Due to pulp canal calcification, location of the root canal was judged to be difficult and associated with a high risk of perforation. A CBCT and an intraoral surface scan were performed and matched using software for virtual planning of guided endodontics. After planning the position of the drill for root canal location, a virtual template was designed and 3D printed which was then used for guided endodontic access.

Keywords: Cone-beam computed tomography, guided endodontics, pulp canal calcification, root canal treatment, three-dimensional printing

How to cite this article:
Nazar AM, George L, Mathew J. Guided endodontics: Management of calcified tooth with a large periapical lesion using cone beam computed tomography and three-dimensional printed guide: A case report. Endodontology 2022;34:131-6

How to cite this URL:
Nazar AM, George L, Mathew J. Guided endodontics: Management of calcified tooth with a large periapical lesion using cone beam computed tomography and three-dimensional printed guide: A case report. Endodontology [serial online] 2022 [cited 2022 Aug 8];34:131-6. Available from: https://www.endodontologyonweb.org/text.asp?2022/34/2/131/349574

  Introduction Top

Pulp canal obliteration, also known as the calcific metamorphosis, is generally considered as the pulpal response to trauma and is undoubtedly characterized by uncontrolled deposition of hard tissue along the root canal walls. There is a myriad of other terms and expressions used in dental literature to designate this condition some of which includes dystrophic calcification, diffuse calcification, or calcific degeneration.[1] This accelerated hard tissue apposition that results in rapid obliteration of root canal space may be a common sequela following traumatic injury, orthodontic therapy, jaw fracture, orthognathic surgery, or autotransplantation of a tooth.[2],[3],[4],[5],[6],[7],[8],[9] Other factors such as caries, coronal restorations, vital pulp therapy, abfraction, and individual aging are also known to trigger this pulp canal obliteration.[10],[11],[12],[13],[14]

This obliteration progresses in a corono-apical direction and therefore partial pulp canal obliterations usually affects the pulp chamber and the coronal part of the canal, whereas the radicular part remains visible, although markedly narrowed.[2],[15] In view of the basis that up to one-quarter of all teeth with posttraumatic pulp canal calcification may develop apical pathology in a protracted time period, thus warranting endodontic intervention, the clinical relevance of such a topic is rather colossal.

On the other hand, the use of conventional approach for such a tooth is prone to various technical failures including alterations of root canal geometry, substantial loss of dental hard tissue which may weaken a tooth considerably, a high risk of perforation as well as over preparation of thin root canals. Within this frame of reference, it has been demonstrated that any alteration of the natural geometry of the root leads to significant changes in tooth rigidity.[16]

To surmount such complications, an innovative “Guided endodontic approach” to locate an obliterated root canal in a tooth with pulp canal calcification and periapical pathology has been introduced. It is a novel guided approach for the preparation of apically extended access cavities for teeth with pulp canal calcifications. It consists of accessing and locating root canals by means of a guiding template created by tomographic orchestration.[17]

Hence, the aim of this case report is to depict novel guided endodontic approach for the management of calcified tooth with a large periapical lesion using cone beam computed tomography (CBCT) and three-dimensional (3D) printed guide.

  Case Report Top

A 48-year-old female patient presented with a chief complaint of swelling on the upper left front tooth region for 8 months. The patient had no history of trauma, however, the patient had a history of orthodontic treatment done about 26 years back. The clinical examination revealed a round, well-defined swelling with a diameter of 1 cm in relation to upper left lateral incisor. The associated tooth was tender on percussion and a negative response was elucidated with both cold and electric pulp testing. The periapical radiograph of upper left lateral incisor revealed round well-defined periapical radiolucency and completely obliterated pulp chamber and pulp canal in the coronal part [Figure 1]. A periapical index score of PAI 5 was assigned based on the changes in surrounding bone and periapical portion.[18] A CBCT (NewTom GiANO HR) scan with a limited field of view and high resolution was performed conforming to the guidelines of the European Society of Endodontology (2014), to allow a more detailed view of the periapical area which revealed a periapical lesion having a diameter of 8.3 mm breaching the labial cortical plate [Figure 2].[19] The Periapical Index Based on CBCT was assigned as score n = 5+ D since there was destruction of periapical cortical bone.[20] The diagnosis was made to be Pulp Necrosis; Chronic Apical Abscess.[21] The measured length of the tooth was approximately 19.5 mm and coronal third of root canal was completely calcified and root canal was only visible at a distance of approximately 7.81 mm from the apex [Figure 3].
Figure 1: (a) Preoperative clinical image showing swelling related to upper left lateral incisor. (b) Periapical radiograph of tooth 22 showing round well-defined periapical radiolucency and a completely obliterated pulp chamber and pulp canal in coronal part

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Figure 2: Cone-beam computed tomography scan showing periapical cystic lesion breaching labial cortical plate and pulp canal calcification

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Figure 3: Root canal visible at a distance of approximately 7.81 mm from the apex which is the apical target point

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Based on the results of clinical and radiographic examination, root canal therapy was the recommended course of treatment. Location of root canal with the conventional method ought to be arduous and associated with a high risk of perforation. Following analysis and discussion with the patient, guided endodontics was chosen as the most appropriate treatment approach for this case and an informed consent was obtained.

A 3D printed template was developed to permit the proposed guided access to the apical third of root canal. Upon obtaining an upper arch silicone impression of the patient, a gypsum dental model was concocted and thereafter scanned using a Model scanner (Identica). Subsequently, both CBCT in DICOM format and the scanned file in STL format were loaded into exocad v2.2-6625 software (Exocad GmbH, Germany) and matched by aligning the contours of teeth. A virtual replica of the drill (Lance pilot drill, Genesis) with a diameter of 1.5 mm and a total length of 30 mm was superimposed on to the scans in a position that sanctioned its access to the identified root canal system within the apical one-third of the tooth. The position was checked in every 3D aspect and the axis of the drill was angled such that the tip of extended drill would reach the radiographically visible apex of the tooth. Thereupon, a virtual sleeve with an inner diameter of 2.35 mm and 5 mm length was planted onto the final template design which was then exported as an STL file for 3D printing (Formlab2, material-dental SG) [Figure 4]. Ultimately, a custom metallic sleeve (Steco-system-technik GmbH and Co KG, Hamburg, Germany) was integrated into the printed template [Figure 5].
Figure 4: Virtual planning of guided endodontic access cavity. (a) Surface tessellation language data of an intraoral surface scan of maxillary teeth. (b) Cone-beam computed tomography and intraoral scan matched by aligning contours of teeth using exocad v2.2-6625 software. (c) Special drill used for root canal location. (d) Virtual copy of drill placed in such a way that the tip of extended drill touches the radiographically visible part of calcified root canal. (e and f) Final template design for guided endodontic access

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Figure 5: Custom metallic sleeve integrated into printed template

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Then, the root canal treatment was initiated without anesthesia under rubber dam. The template was positioned on the anterior maxillary teeth and correct fitting was checked. After attesting the adaptation of the guide, a mark was placed through template sleeve to designate exact region of endodontic access cavity and to accommodate as reference point to commence the opening access. In this case, the access cavity was extended up to the incisal edge for a straight-line access to be acquired. Access opening was then initiated by means of a high-speed long-neck round diamond bur (BR-154, MANI), and the enamel was meticulously extracted until the underlying dentine was exposed. The position of drill coupled to an implant motor set at 2000 RPM was checked in the mouth and consequently, the drilling was performed under copious saline irrigation using pumping movements to penetrate through calcified portion of root canal in order to gain access to the supposedly uncalcified apical region [Figure 6]. During preparation, the drill was cleaned regularly of its debris and the root canal was thoroughly irrigated using 3% sodium hypochlorite. After each 2 mm gain in depth, radiographs taken at two different angulations were used to confirm the exact position of the bur, and in addition, a 10 size K-file (Mani) was used to check whether root canal could be negotiated at that depth [Figure 7]a. This was possible at a distance of 7 mm from the apex which was nearly equipollent to our apical target point. The remaining canal was negotiated from that point on with a 10-size K-file (Mani), used in a gentle watch winding motion. The working length was determined to be 19 mm using apex locator and was verified radiographically [Figure 7]b. The apical preparation was done up to size 40 K file and stepback preparation was done up to size 55 K file. Sodium hypochlorite (3%) was used for irrigation along with a final irrigation protocol performed with 17% ethylenediaminetetraacetic acid and 3% sodium hypochlorite. The irrigant was activated with a calibrated master cone using a manual dynamic activation technique in addition to sonic activation (EndoActivator, Dentsply, USA). Upon drying the root canal with paper points, a calcium hydroxide inter-appointment dressing (RC Cal) was placed and the access cavity was sealed with Cavit (3MESPE, USA). Subsequently, after 2 weeks, canal was cleaned and dried with paper points. Metapex (META BIOMED, Korea) was placed in the canal and cavity was sealed with cavit [Figure 7]c. The patient was reviewed after 1, 2, and 3 months [Figure 7]d, [Figure 7]e, [Figure 7]f.
Figure 6: (a) Template positioned on the maxillary teeth to check its correct fitting. (b) Mark placed through template sleeve to indicate exact region of endodontic access cavity preparation. (c) Drill coupled to an implant motor and drilling performed with pumping movements to penetrate through calcified part of root canal. (d) View of minimally invasive access cavity after root canal location using this technique

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Figure 7: Radiographs were taken during root canal treatment. (a) Small-sized file used to check whether root canal could be negotiated at that depth. (b) Working length determination. (c) Metapex obturation. (d-f) After 1, 2, and 3 months of metapex placement

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Finally, after 3 months when the swelling had resolved completely and healing was observed radiographically, the root canal was obturated with gutta-percha and AH Plus sealer (Dentsply, USA) using lateral condensation technique. The obturation material was reduced 1 mm below the CEJ and the access cavity was cleaned and restored with a composite material [Figure 8]. However, it was noted that the tooth has become yellowish following 3 months of treatment with Metapex for which the patient requested correction. Since there was only a minimal loss of tooth structure observed using the guided approach, a veneer was rendered as the best available treatment option, for which the patient consented in toto.
Figure 8: Radiographs showing (a) Master cone placement (b) Obturation

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Thereafter, an IPS e.max Lithium Disilicate (Ivoclar Vivadent) veneer was cemented conforming to the clinical guidelines provided by the manufacture [Figure 9]. The patient was followed up for 2 years, the tooth was asymptomatic, and good healing was observed both clinically and radiographically [Figure 10]. Since the patient was not willing for a follow-up CBCT scan, the outcome measurement was done using PAI scores of pre and postoperative radiographs and healing/nonhealing were assessed according to those scores. The preoperative PAI score of 5 was reduced to PAI-2 postoperatively, indicating a healed lesion, and thus, the treatment was deemed as “successful” [Figure 11].[18]
Figure 9: (a) Ceramic Veneer preparation (b) Cementation of ceramic veneer

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Figure 10: Follow-up examinations: (a) periapical radiograph after 12 months, (b) clinical view after 12 months, (c) periapical radiograph after 2 years, (d) clinical view after 2 years

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Figure 11: Pre and postoperative radiographs showing reduction in PAI scores indicating a successful outcome

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  Discussion Top

This is the first case report describing the nonsurgical management of a maxillary lateral incisor with pulp canal calcification and a large periapical lesion using the novel Guided Endodontics technique. The American Association of Endodontists has rightly relegated such cases with radiographically invisible root canals in the highest difficulty level owing to the capricious nature of their treatment outcome which may prove to be challenging even for the most skilled practitioner.[22]

In such cases, guided endodontic access may be indicated for a more predictable access, allowing maximum preservation of the dental structure and also reducing iatrogenic accidents which might guarantee an ameliorated long-term prognosis.[19],[23] In an in vitro study conducted by Connert et al., using the conventional technique, 10 out of 24 root canals were accessed and negotiated (41.7%) whereas location and negotiation using guided endodontics were achieved in 22 out of 24 root canals (91.7%).[22] It was concluded by the authors that the guided endodontic access leads to a more predictable and expeditious location of calcified root canals with significantly less substance loss compared to the conventional endodontic access.

In the study conducted by Zehnder et al., deviations of planned and prepared access cavities were low with means ranging from 0.16 to 0.21 mm for different aspects at the base of the bur and 0.17 to 0.47 mm at the tip of the bur. In addition, the mean of angle deviation was 1.81°. These results suggested a high accuracy of the “Guided Endodontics” technique with a negligible influence of the operator.[23]

One of the inadequacies noted in the presented approach is that, the substance loss and modifications of the innate root canal geometry according to the dimension of the drill must be accepted. The loss of hard tissue is analogous to a postspace preparation and leads to concentric substance loss around the calcified root canal.[24] Nonetheless, dentin losses resulting from the attempt to conventionally locate calcified root canals can occur in any direction and lead to an unpredictable destruction of the root.

Another limitation of this technique is the straight drill path which does not take into account the natural curvatures within a root canal, although the chances of a root canal being completely calcified up to its apical third are rather dubious. It is therefore imperative to consider that this technique has anatomical constraints not only in severely curved canals but also in the presence of radicular grooves, isthmuses, or oval roots.[25] A lack of interocclusal distance to accommodate the template and the additional instrument length required may also pose quite a challenge while employing this technique.[26] As a result, this technique might as well be contraindicated in curved canals and patients with limited mouth opening.

Another important source of concern is the possibility of dentinal cracks as a result of the stresses generated at the bur's tip, as well as excessive heat production, which could affect the periodontal ligament and alveolar bone. Thus cooling is of great importance while performing guided endodontics.[27]

Calışkan et al. rightly stated that in approximately 70% of cases with periapical lesion, the healing was apparent within 2 years of treatment. In the presented case, the tooth was obturated after 3 months and was further followed up for 2 years after which resolution of lesion was observed both clinically and radiographically.[28]

  Conclusion Top

All things considered, the use of guided endodontics approach seems to be a safe, clinically feasible method for locating root canals and preventing root perforation in teeth with pulp canal calcification that cannot be predictably accessed through traditional endodontic therapy. In this case report, nonsurgical treatment with the use of calcium hydroxide-iodoform-silicon-oil paste (Metapex) proved to be successful in promoting the healing of a large periapical lesion. This confirms that even large periapical lesions can respond favorably to nonsurgical treatment and therefore, it must always be the first treatment of choice.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Reis LC, Nascimento VD, Lenzi AR. Operative microscopy – Indispensable resource for the treatment of pulp canal obliteration: A case report. Braz J Dent Traumatol 2009;1:23-6.  Back to cited text no. 1
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. 2
Oginni AO, Adekoya-Sofowora CA, Kolawole KA. Evaluation of radiographs, clinical signs and symptoms associated with pulp canal obliteration: An aid to treatment decision. Dent Traumatol 2009;25:620-5.  Back to cited text no. 3
Abd-Elmeguid A, ElSalhy M, Yu DC. Pulp canal obliteration after replantation of avulsed immature teeth: A systematic review. Dent Traumatol 2015;31:437-41.  Back to cited text no. 4
Popp TW, Artun J, Linge L. Pulpal response to orthodontic tooth movement in adolescents: A radiographic study. Am J Orthod Dentofacial Orthop 1992;101:228-33.  Back to cited text no. 5
Roed-Petersen B, Andreasen JO. Prognosis of permanent teeth involved in jaw fractures. A clinical and radiographic follow-up study. Scand J Dent Res 1970;78:343-52.  Back to cited text no. 6
Vedtofte P. Pulp canal obliteration after Le Fort I osteotomy. Endod Dent Traumatol 1989;5:274-8.  Back to cited text no. 7
Kristerson L. Autotransplantation of human premolars. A clinical and radiographic study of 100 teeth. Int J Oral Surg 1985;14:200-13.  Back to cited text no. 8
Andreasen JO, Paulsen HU, Yu Z, Bayer T, Schwartz O. A long-term study of 370 autotransplanted premolars. Part II. Tooth survival and pulp healing subsequent to transplantation. Eur J Orthod 1990;12:14-24.  Back to cited text no. 9
Sayegh FS, Reed AJ. Calcification in the dental pulp. Oral Surg Oral Med Oral Pathol 1968;25:873-82.  Back to cited text no. 10
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. 11
Agamy HA, Bakry NS, Mounir MM, Avery DR. Comparison of mineral trioxide aggregate and formocresol as pulp-capping agents in pulpotomized primary teeth. Pediatr Dent 2004;26:302-9.  Back to cited text no. 12
Johnstone M, Parashos P. Endodontics and the ageing patient. Aust Dent J 2015;60 Suppl 1:20-7.  Back to cited text no. 13
Kiefner P, Connert T, ElAyouti A, Weiger R. Treatment of calcified root canals in elderly people: A clinical study about the accessibility, the time needed and the outcome with a three-year follow-up. Gerodontology 2017;34:164-70.  Back to cited text no. 14
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Lang H, Korkmaz Y, Schneider K, Raab WH. Impact of endodontic treatments on the rigidity of the root. J Dent Res 2006;85:364-8.  Back to cited text no. 16
Lara-Mendes ST, Barbosa CF, Santa-Rosa CC, Machado VC. Guided endodontic access in maxillary molars using cone-beam computed tomography and computer-aided design/computer-aided manufacturing system: A case report. J Endod 2018;44:875-9.  Back to cited text no. 17
Orstavik D, Kerekes K, Eriksen HM. The periapical index: A scoring system for radiographic assessment of apical periodontitis. Endod Dent Traumatol 1986;2:20-34.  Back to cited text no. 18
Bhatt M, Coil J, Chehroudi B, Esteves A, Aleksejuniene J, MacDonald D. Clinical decision-making and importance of the AAE/AAOMR position statement for CBCT examination in endodontic cases. Int Endod J 2021;54:26-37.  Back to cited text no. 19
Estrela C, Bueno MR, Azevedo BC, Azevedo JR, Pécora JD. A new periapical index based on cone beam computed tomography. J Endod 2008;34:1325-31.  Back to cited text no. 20
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Connert T, Krug R, Eggmann F, Emsermann I, ElAyouti A, Weiger R, et al. Guided endodontics versus conventional access cavity preparation: a comparative study on substance loss using 3-dimensional–printed teeth. J Endod 2019;45:327-31.  Back to cited text no. 22
Zehnder MS, Connert T, Weiger R, Krastl G, Kühl S. Guided endodontics: Accuracy of a novel method for guided access cavity preparation and root canal location. Int Endod J 2016;49:966-72.  Back to cited text no. 23
Lara-Mendes ST, Barbosa CF, Machado VC, Santa-Rosa CC. A new approach for minimally invasive access to severely calcified anterior teeth using the guided endodontics technique. J Endod 2018;44:1578-82.  Back to cited text no. 24
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Buchanan LS. Dynamic CT-Guided Endodontic Access Procedures. Dent Edu Lab. 2018 Jan.  Back to cited text no. 26
Moreno-Rabié C, Torres A, Lambrechts P, Jacobs R. Clinical applications, accuracy and limitations of guided endodontics: A systematic review. Int Endod J 2020;53:214-31.  Back to cited text no. 27
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]


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