|Year : 2022 | Volume
| Issue : 4 | Page : 293-299
A simplified and cost-effective targeted endodontic guide for calcified canal negotiation and surgical management
MR Pradeepa1, B Rahul1, CT Valliappan1, I Anand Sherwood1, James L Gutmann2, Rathna Piriyanga Subramani1, A Andamuthu Sivakumar3
1 Department of Conservative Dentistry and Endodontics, CSI College of Dental Sciences, Madurai, Tamil Nadu, India
2 Professor Emeritus, Department of Endodontics, Texas A and M University College of Dentistry, Dallas, Texas, USA
3 Department of Conservative Dentistry and Endodontics, Vivekanandha Dental College for Women, Trichengode, Tamil Nadu, India
|Date of Submission||18-Feb-2022|
|Date of Decision||27-Apr-2022|
|Date of Acceptance||02-Jul-2022|
|Date of Web Publication||28-Dec-2022|
Prof. I Anand Sherwood
Department of Conservative Dentistry and Endodontics, CSI College of Dental Sciences, 129, CMH Compound, E Veli Steet, Madurai - 625 001, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Management of pulp canal obliteration and apicoectomy procedures with an endodontic guide is presented in multiple cases. This case report series highlights a cost-effective guide construction approach using an open-source cone-beam computed tomography software, ITK-snap. A simple soft template was used as a guide for successful access of calcified canals and osteotomy preparation with reduction of unwarranted adjacent tissue damage.
Keywords: Access preparation, apicoectomy, cone-beam computed tomography, endodontic guide, ITK-snap, pulp canal obliteration
|How to cite this article:|
Pradeepa M R, Rahul B, Valliappan C T, Sherwood I A, Gutmann JL, Subramani RP, Sivakumar A A. A simplified and cost-effective targeted endodontic guide for calcified canal negotiation and surgical management. Endodontology 2022;34:293-9
|How to cite this URL:|
Pradeepa M R, Rahul B, Valliappan C T, Sherwood I A, Gutmann JL, Subramani RP, Sivakumar A A. A simplified and cost-effective targeted endodontic guide for calcified canal negotiation and surgical management. Endodontology [serial online] 2022 [cited 2023 Jan 28];34:293-9. Available from: https://www.endodontologyonweb.org/text.asp?2022/34/4/293/365814
| Introduction|| |
Adoption of limited volume cone-beam computed tomography (CBCT) imaging in dentistry and higher resolution of the maxillomandibular complex had led to the fabrication of guides for more precise endodontic surgical procedures and predictable canal location in calcified complex cases.,,,, Conventional guides or stents involve the integration of CBCT images with an intra-oral scan or digitized plaster treatment model. Previously proposed approaches to constructing guides involved transforming the patient's anatomy into digital data in four steps. This requires the usage of multiple, subscription-based software applications. Ray et al. identified a 4-step process of digital workflow, including (i) bone, teeth, and neurovascular spaces rendered with CBCT imaging; (ii) crowns and soft tissues rendered with an intraoral optical scan, a benchtop optical scan of an impression or cast, or a CBCT scan of an impression or cast; (iii) merging of renderings within a specific design software to create a 3-dimensional (3D) construction containing a virtual model with a guide designing; and (iv) at last, the guide design is carried out on the virtual model for 3D printing. George et al. addressed the impracticality of these processes in normal clinical or laboratory settings, due to increased time and expense. The employment of multiple software platforms was not user-friendly and required a steep learning curve for many clinicians.
This case report presents a cost-effective usage of open-source 3D segmentation software ITK-Snap for rendering CBCT imaging and construction of a guide using a soft splint from a patient's intraoral plaster cast.
| Pulp Canal Obliteration of Maxillary Central Incisor|| |
An 18-year-old female patient reported with a complaint of pain in the discolored right maxillary central incisor following trauma. The teeth did not respond to the cold pulp sensibility test (Roeko Endo Frost, Coltene, Whaledent Ltd., USA) [Figure 1]a. Pain on percussion was evident. Digital periapical radiograph (VistaScan Mini Easy, Durr Dental SE, Bietigheim-Bissingen, Germany) examination showed loss of lamina dura and widening of the periodontal ligament space along the entire length of the right maxillary central incisor that was associated with periapical bone rarefaction [Figure 1]b. The symptomatic right maxillary central incisor displayed extensive calcification of the pulp chamber and root canal [Figure 1]b. The treatment option proposed was nonsurgical root canal treatment.
|Figure 1: (a) Pretreatment photograph of an 18-year-old female patient with discolored painful PCO right maxillary central incisor. (b) Pretreatment radiograph arrow pointing to obliterated root canal in right maxillary central incisor. (c) CBCT scan with arrows pointing to right maxillary central incisor with obliterated root canal space. (d and e) Segmentation of tooth structure and desired access preparation location in ITK-Snap software. (f) 3D model printed in opaque grey resin with proposed access preparation dimension and location. (g and h) Soft splint constructed from patient's stone model checked for fitting with the 3D model. (i) Soft splint tray fitted in patient's mouth. (j) Access preparation with splint in position. (k and l) Working length radiograph. (m) Immediate post obturation radiograph depicting no pericervical dentin removal nor change in access preparation orientation. PCO: Pulp canal obliteration, CBCT: cone beam computed tomography, 3D: 3-dimensional|
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Informed consent was obtained before guided endodontic intervention. A limited volume CBCT scan was obtained using Kodak CS 8100 3D (Carestream Dental, Atlanta, USA) and KaVo OP 3D Pro (KAVO Dental, CA, US) CBCT machine confirming radiograph finding of minimal root canal pathways in the maxillary central incisors [Figure 1]c. The most accurate pulpal diagnosis, according to clinical and imaging examination was pulp canal obliteration (PCO) for the maxillary central incisors. The periapical diagnosis was symptomatic apical periodontitis and acute apical abscess. Guided endodontic access preparation was planned in the maxillary central incisors for locating the root canal.
In this case report, segmentation/rendering of the bone, pulp canal spaces, periapical lesion, and tooth tissues from CBCT were done by semi-automatic segmentation using ITK-Snap following established protocols [Figure 1]d. The anatomic structures in the CBCT scan were segmented, using a separate label and exported. Segmentation was followed by forceful separate-labeled segmentation of the preferred access location of 2.5 mm in diameter and 4–5 mm in-depth on the palatal aspect of the PCO maxillary central incisor coinciding with the location of the pulp chamber and canal orifice [Figure 1]e. CBCT Digital Imaging and Communication in Medicine (DICOM) files were exported using the Standard Tessellation Language (STL) model format in ITK-Snap software. The STL file was used for printing a 3D model [Figure 1]f; the PCO maxillary central incisors had an access cavity on the palatal aspect [Figure 1]f.
The second and third stages of conventional guide fabrication, i.e., STL file rendering of the dentition followed by overlaying of the CBCT and dentition STL files in a 3D design software are eliminated in this present report. Instead of these steps, a soft splint is constructed on the patients' maxillary plaster cast to act as a guide [Figure 1]g. The 3D model is seated in the soft splint and an indelible mark is placed in the splint coinciding with the access cavity in the PCO maxillary central incisor [Figure 1]h and [Figure 2]g. The marked location in the splint is drilled for a perforation; following this the splint is fitted in the patient's maxillary arch to check for the adaptation and appreciate the access location on the tooth surface [Figure 1]i and [Figure 2]h.
|Figure 2: (a) Pretreatment photograph of 35-year-old female patient with full coverage ceramic crown in both maxillary central incisors. (b) Intraoral periapical radiograph showing periapical lesion in relation to root canal treated right maxillary central incisor. (c) CBCT scan displaying labial cortical plate destruction in periapex of right maxillary central incisor (arrow). (d and e) Previous root canal filing removed followed by Biodentine filling of root canal space. (f and g) CBCT segmentation of tooth and adjacent bone structures with ITK-Snap software. (h) 3D model print out with opaque grey resin material. (i and j) Soft splint fitting check in patient's stone model with flap design and bone defect marked. (k-m) Soft splint placed in patient's mouth prior and during surgical procedure. (n) Placement of bone substitute in the bone defect. (o) Immediate postsurgical radiograph showing evidence of root-end resection and bone graft placement. (p) Suture placement to approximate the flap. (q) Soft healing at the suture removal phase. CBCT: Cone beam computed tomography, 3D: 3-dimensional. (r) 6 months recall photograph showing excellent soft tissue healing|
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After a secure fit of 3D guide, access was prepared, under dental dam isolation [Figure 1]j and [Figure 2]i using a round diamond abrasive (2–0 Mani Co., Tochigi, Japan) operated with a high-speed water-cooled air rotor handpiece. A size # 10 or 15 K-file (Mani Co., Tochigi, Japan) was used for the initial negotiation of the root canal orifice. Working length was recorded using an electronic apex locator (E-pex Pro [Orikam Healthcare, Gurugram, India]) and digital radiograph [Figure 1]k, [Figure 1]l and [Figure 2]j. Chemomechanical preparation of canal space was performed with Neoendo Flex file system (Orikam Healthcare, Gurugram, India) and the canal was enlarged up to size F2 using repeated irrigation with 3% sodium hypochlorite (Parcan, Septodont India Healthcare Pvt Ltd, Raigad, India). Calcium hydroxide (Prime Dental Products, Mumbai, India) intra-canal medicament was placed for 15 days followed by single-cone obturation using greater taper gutta-percha (Neoendogutta-percha points, Orikam Healthcare, Gurugram, India) corresponding to the file size was using with zinc oxide eugenol (Endoseal, PrevestDenPro, India) as sealer [Figure 1]m and [Figure 2]k.
Guided access preparation was precise with no pericervical dentin removal to locate the canal orifices [Figure 1]k and [Figure 2]k. At the 6-month review of the patient, no discomfort to percussion or palpation in the treated teeth was observed and the patient's function was normal.
| Apical Surgical Guide|| |
A 35-year-old female patient reported with pain and swelling in relation to root canal-treated maxillary central incisors [Figure 2]a. Clinical examination showed both the maxillary central incisors with full coverage ceramic crowns and periapical tenderness in relation to the right maxillary central incisor [Figure 2]a. Digital periapical radiography displayed inadequate root canal filling short of root canal apical constriction in both right and left maxillary central incisors, slight periapical bone rarefaction was observed in relation to left maxillary central incisor, and large periapical radiolucency with apical root resorption evident in the right maxillary central incisor [Figure 2]b. Maxillary lateral incisors responded positively to the cold pulp sensibility test and did not show any clinical symptoms. Since root canal treatment was completed 6 years ago, retreatment for only the right maxillary central incisor followed by apicoectomy was suggested. CBCT scan examination (CS 8100 3D, Carestream Dental, Atlanta, USA) showed a large periapical radiolucency root apex of the right maxillary central incisor with cortical plate perforation [Figure 2]c. Pulpal diagnosis was previously root canal treated maxillary incisors and periapical diagnosis of a chronic apical abscess. Retreatment for the right maxillary central incisor was initiated with the removal of full-coverage crowns. The previous gutta-percha root filling was removed using ProTaper Universal Rotary Retreatment Files (Dentsply, Pennsylvania, United States) from the canal followed by a freshly prepared mixture of calcium hydroxide with saline as intra-canal medicament placement for 15 days [Figure 2]d. A Biodentine root canal filling was placed to increase the fracture resistance of the tooth [Figure 2]e. The previously removed full-coverage crowns were used as temporary replacements until the completion of the surgical procedure.
The surgical guide design and fabrication were done as explained earlier using the ITK-Snap tool [Figure 2]g and [Figure 2]h. A soft splint constructed from the patient's plaster cast as explained previously, acted as a surgical stent [Figure 2]i. The periapical bone defect and proposed incision lines were marked in the soft splint with aid of the 3D model [Figure 2]j. The splint was checked for fit in the patient's maxillary arch [Figure 2]k and cut along the marked incision lines to aid in the placement of incisions intraorally [Figure 2]l. A full-thickness flap was elevated followed by periapical curettage and apical root-end resection [Figure 2]m. Retrofilling was not required in this case as the canal was obturated with biodentine. Resorbable Tissue Replacement (R.T.R) bone substitute (Septodont India Healthcare, Raigad, India) was placed in bone defect [Figure 2]n and [Figure 2]o. Ethilon 4–0 sutures (Johnson and Johnson Pvt Ltd., Baddi, India) were used to reposition and stabilize the tissue flap [Figure 2]p. Sutures were removed after 7 days, and soft-tissue examination showed excellent healing [Figure 2]q. At the 6-month recall visit, the patient was asymptomatic, displaying healthy gingival tissues [Figure 2]r.
A 29-year-old male reported with complaints of pain in the discolored right maxillary central incisor and lateral incisor following trauma. Both the teeth did not respond to the cold pulp sensibility test. Pain on percussion was evident in both 11 and 12. Clinical examination showed an intra-oral apical swelling between the right maxillary central and lateral incisor [Figure 3]a and [Figure 4]a. Digital periapical radiograph examination showed loss of lamina dura and widening of the periodontal ligament space along the entire length with periapical bone rarefaction and bone defect in the root apex of the right maxillary central incisor. In addition, a root canal-filled right maxillary lateral incisor was seen with associated periapical lesion and labial cortical plate perforation [Figure 3]b and [Figure 4]b. The symptomatic right maxillary central incisor displayed extensive calcification of the pulp chamber and root canal [Figure 3]b. Two treatment options proposed were root canal retreatment, apical root-end resection (apicoectomy) in 12, and curettage of the periapical lesion by surgical method following root canal treatment for the maxillary central incisor 11.
|Figure 3: (a) Pretreatment photograph of 29-year-old male patient with complaints of swelling and pain in relation to right maxillary central incisor. (b) Preoperative radiograph with arrows pointing to periapical lesion in left and right maxillary central incisor along with obliterated canal space in right maxillary central incisor. (c) CBCT scan showing obliterated canal space (arrow) and cortical plate perforating periapical lesion (arrow) of the right maxillary central incisor. (d) CBCT segmentation of tooth and adjacent bone structures with ITS-Snap software. (e) 3D stimulation of the segmented portion in ITK-Snap software. (f) 3D model print out of right maxillary incisor to canine in transparent resin material with arrow pointing to proposed access preparation in right maxillary central incisor. (g) Soft splint tray fit checked with 3D model. (h and i) Soft splint in patient's mouth for the access preparation. (j and k) Minimal pericervical dentin removal or access misdirection demonstrated in the working length estimation and post obturation radiographs. CBCT: Cone beam computed tomography, 3D: 3-dimensional|
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|Figure 4: (a) Presurgical photo of 29-year-old male patient with complaint related right maxillary incisors. (b) Presurgical radiograph with arrow pointing to periapical defect. (c) CBCT scan with arrows denoting labial cortical plate perforation of the periapical lesion in region of right maxillary lateral incisor. (d) CBCT segmentation of tooth and adjacent bone structure from right maxillary central incisor to canine with ITK-Snap software. (e) Soft splint fit check with 3D model. (f and g) Fit check of soft splint in patient's stone model and mouth with proposed flap design and osteotomy window region marked in the guide. (h and i) Osteotomy window preparation located in close proximity to marked region in the soft splint. (j) Bone substitute placement. (k). Immediate postsurgical radiograph depicting root resection in right maxillary lateral incisor. (l). Suture placement to approximate the flap. CBCT: Cone beam computed tomography, 3D: 3-dimensional. (m) 6 months recall photograph showing excellent soft tissue healing|
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Informed consent was obtained from the patient prior to guide endodontic intervention. A CBCT scan (KaVo OP 3D, [KaVo Dental GmbH, Biberach, Germany] with a FOV limited to a maximum of eight teeth with an exposure of 90 kVp, 10 mA, and a voxel size of 70 μm) examination showed a pulp canal obliteration in the right maxillary central incisor [Figure 3]c and a large periapical lesion perforating the labial cortical plate in relation to apex of the right maxillary lateral incisor [Figure 4]c. The periapical diagnosis was an acute apical abscess. First guided endodontic access preparation was planned in the right maxillary central incisor for locating the root canal. Access guide design and fabrication protocols were similar to case 1 [Figure 3]d and [Figure 3]e. For this case with planned apical root-end resection surgery, a single 3D model was designed for both guiding the access preparation and apical root-end resection. The root canal treatment was performed following the same protocol as in case 1 [Figure 3]f, [Figure 3]g, [Figure 3]h, [Figure 3]i, [Figure 3]j, [Figure 3]k.
Retreatment was initiated for 12. The previous root canal filling material was removed using H files (Mani Co., Tochigi, Japan), ProTaper Universal Rotary Retreatment Files (Dentsply, Pennsylvania, United States) from the canal followed by a freshly prepared mixture of calcium hydroxide with saline as intra-canal medicament placement for 15 days Biodentine apical plug with middle and coronal 3rd of root canal filling was done with thermoplasticized gutta-percha [Figure 4]b.
Surgical guide design and fabrication protocols were similar to the previous cases [Figure 4]d and [Figure 4]e. Surgical guide employment for osteotomy was done as in the previous case [Figure 4]e, [Figure 4]f, [Figure 4]g, [Figure 4]h, [Figure 4]i. Root end resection of the right maxillary lateral incisor was done [Figure 4]k. Bone substitute (Bio-Oss, Geistlich Pharma AG, Wolhusen, Switzerland) and platelet-rich fibrin from the patient's own blood was placed in the bone defect [Figure 4]j. The elevated soft tissue was repositioned and sutured [Figure 4]l and the patient was seen after 6 days for suture removal [Figure 4]m. At the 6-month recall visit, the teeth 11 and 12 were asymptomatic, no radiograph findings of periapical breakdown were evident and soft-tissue healing was excellent [Figure 4]m.
| Discussion|| |
Presurgical/endodontic planning with CBCT and a variety of planning software is a widely accepted norm for PCO management and apicoectomy., These case reports highlight the successful use of ITK-Snap for the segmentation of anatomic structures in CBCT. Access and surgical guides fabricated and provided for the treatment procedures were found to be time-efficient and precise., However, the present work differs from previous ones in the use of open-source segmentation software to convert DICOM files to the STL model.,,,, Furthermore, a cost-effective soft splint guide fabrication allowed for both precise root canal access and surgical osteotomy window preparations with minimal damage to adjacent structures.
Access preparation in PCO maxillary incisors was accurate in the location of the obliterated canal with no additional removal of pericervical dentin. A marked perforated window prepared in the soft splint was so precise that the obliterated canal was located immediately on the pulp roof removal with no adjustments required in access preparation. Straight-line access with thorough cleaning and shaping of the canal until the working length as possible in both cases of PCO maxillary incisors. The soft splint was trimmed off around the canines to allow for rubber dam application. 3D models were printed in two types of resin one in an opaque gray color and another in transparent resin material. The opaque grey color resin had better contrast, thereby providing better visualization of access location in the model. Neither patient reported discomfort in placement or the presence of a soft splint during the treatment procedure.
The use of a surgical guide in the present case report allowed for minimal flap design extension and unwarranted adjacent soft-tissue disturbance, a precise osteotomy window preparation with no sequential adjustments, and reduced chair time. In both surgical patients, there was no postsurgical inconvenience and soft-tissue healing was excellent. Efficient osteotomy and root resection with guided surgery have been associated with a better healing process., Bone substitutes were able to be placed in both surgical cases.
Guides were prepared from two CBCT machines, both of which provided similar results. No additional metal sleeve or custom-designed burs were required to locate the canal or to create an osteotomy window. Minor trimmings were done to 3D models for precise adaptation of the soft splints with the models; this was similar to an earlier report. Ray et al. discussed the potential sources of errors in the digital workflow of CBCT-guided construction. These issues could have been the reason behind minor adjustments required in the 3D models. The main limitation of this report is the guide was used for only maxillary incisor tooth management, as future reports on the capabilities of this technology in different regions of the jaw are necessary.
| Conclusions|| |
This report highlights the ability of segmentation software ITK-Snap for the construction of the 3D model and the novel usage of soft splint as a cost-efficient guide for both access and osteotomy preparation in an obliterated root canal negotiation and root-end surgical procedures, respectively in maxillary incisors. ITK-Snap software was efficient for 3D-model construction in a single patient with multiple treatment requirements.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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