Three-dimensional printing: A revealing pathway to an unpredictable maze.

Three-dimensional (3D) technology has gained wide acceptance in dentistry. It has been used for treatment planning and surgical guidance. This case report presented a novel treatment approach to remove and preserve the cortical bone and root-end resection during periapical surgery with the help of cone-beam computed tomography (CBCT), computer-aided design, and 3D printing technology. A 22-year-old male patient presented with a large periapical lesion in the right maxillary central and lateral incisors was referred for endodontic surgery. The data acquired from a preoperative diagnostic CBCT scan and an intraoral scan were uploaded into surgical planning software and matched. A template that could be used to locate root ends and lesion areas was virtually designed based on the data and was fabricated using a 3D printer. With the guidance of the template, the overlying cortical bone was precisely removed and preserved, and apicectomy was performed. The patient was clinically asymptomatic at a 6-month follow-up review. Six months after the surgery, the lesion was healing well, and no periapical radiolucency was observed on radiographic examination. The digitally designed directional template worked in all aspects to facilitate the periapical surgery as anticipated. The root ends were accurately located and resected. The surgical procedure was simplified, and the treatment efficiency was improved. This technique minimized the damage and reduced iatrogenic injury. Copyright:

INTRODUCTION

Traumatic dental injuries are common in permanent dentition with 33% of adults experiencing it mainly before 19 years of age.[1] Many patients report late because of lack of symptoms, and discoloration of the teeth is the only driving force. An incidental finding of large periapical lesions in a traumatized tooth is very common. Most of the cases are responsive to conventional nonsurgical root canal treatment. However, a weeping canal secondary to an infected periapical cyst may require surgical intervention.[23]

Untreated large periapical cyst can cause external root resorption and pathological migration of the involved tooth. Expansion of the cortical plate is the common site in such cases. In the maxillary jaw, either buccal or palatal plate could get eroded, whereas in the mandible, it is the labial or buccal cortical plate which is more commonly involved.[2] Buccal approach is always the preferred choice for the visibility and convenience of performing surgery. Numerous cases present with large periapical lesions with both cortical plates intact. Such situations present a surgical dilemma of how to approach the site. Conventional technique would lead to a considerable amount of bone removal for performing complete enucleation and root-end management.[3] Hence, there is a need for a technique which can allow preservation of the cortical plate and give convenience to perform the surgery.

The pivotal role which cone-beam computed tomography (CBCT) plays in nonsurgical and surgical endodontics is well proven now. Surgical treatment planning can be effectively done. Starting from the measurement of the lesion size, the proximity of the neurovascular bundles, and difficult areas to reach for enucleation, all can be marked using the same.[4] To complement CBCT, three-dimensional (3D) printing has come a long way. 3D templates have been recently introduced in endodontics for osteotomy and guided access preparation in calcified canals. The combination of CBCT and 3D printing has opened up doors to perform most difficult surgeries with minimal difficulties while preserving the tissues.

The present case highlights how CBCT and 3D printing were used effectively to design a template which helped in preserving the buccal cortical plate and allowed enough access to reach the most distant parts of the bony cavity while performing endodontic surgery.

CASE REPORT

A 22-year-old healthy male patient reported to the department with a chief complaint of pain on biting hard food in the upper right anterior teeth for the past 1–2 weeks. He had a history of trauma while playing cricket 6–7 years ago. The patient had no significant medical history. The dental history included composite restorations done in the upper front teeth 3 years back.

Clinical examination revealed discolored old composite restoration with 11, 12, and 21 and amalgam restoration in relation to 16. Furthermore, Angle's Class 3 malocclusion with anterior crossbite was noted. The right central incisor was slightly tender on percussion. There were no signs of mobility, swelling, pus discharge, sinus tract, or inflammation of the gingiva. Electric pulp testing showed no response in relation to 11 and 12, and the response was delayed for 13. Intraoral periapical radiograph revealed coronal radiopacity suggestive of Class 3 restorations and a large periapical radiolucency in relation to 11, 12, and 13. The radiolucency measured was 1.5 cm × 1 cm extending from the mesial surface of 11 to the mesial surface of 13 [Figure 1b]. Based on the findings, a final diagnosis of symptomatic apical periodontitis was formulated. The success of nonsurgical treatment in lesions >15–20 mm is less.[35] Here, the size was doubtful, so the patient was explained to the possibility of surgical approach as well. As the patient had plans of migrating to another country in the coming months, a consensus was reached and surgical approach was opted. To plan the surgery and acquire a detailed view of the region of interest, a small field of view (FOV) 4 cm × 4 cm CBCT scan was advised.

Figure 1

(a) Preoperative cone-beam computed tomography, (b) preoperative radiograph, (c) working length determination, (d) master cone, (e) obturation radiograph, (f) schematic diagram of surgical template, (g) fabrication surgical template using computer-aided design, (h) postoperative radiograph, (i) after 3-month follow-up, (j) after 6-month follow-up

The CBCT revealed a well-defined radiolucent lesion with an approximate size of 15.94 mm × 11.63 mm at the apices of the upper right central and lateral incisor. Both the incisors had one canal, and no deviations from the normal root anatomy could be inferred [Figure 1a]. Irrespective of its enormous size, interestingly, the buccal cortical plate was completely intact. The situation presented a challenge of preserving the buccal cortical plate. Complete enucleation would have demanded unprecedented cutting of the cortical bone which, if preserved, would provide soft tissue stability and enhance the healing rate. Hence, a 3D-guided surgery was planned aiming to print a template which would allow removal of a cortical bone segment in the block which would be placed back at its original site.

After administering local anesthesia, primary endodontic treatment was initiated under rubber dam isolation for all the three teeth, and working length was determined [Figure 1c]. Biomechanical preparation was done using K files owing to the large size of the canal, and apical preparation was finished at #45. Interim calcium hydroxide (RC Cal, Prime Dental, Thane, India) dressing was placed. The dressing was changed 3–4 times at an interval of 10–12 days. Obturation was done with gutta percha (DiaDent, Korea) and resin sealer (AH Plus, Dentsply, Germany) with lateral compaction technique, followed by a composite (Solare-X, GC Dental products, Japan) postendodontic restoration [Figure 1d and e].

Schematic diagram of the template was prepared for communicating with the template designer. The outline of the template was devised to be smaller than the lesion size but at the same time allow a curette of shank length 14 mm to reach and remove the complete lining of the lesion from the most distant parts. The thickness of the template was 1.5 mm. It was designed to be 2–3 mm away from the intact cortical plate and about 5 mm away from the mesial border of the canine (13). The inner diameter of the lower border extended just enough to cover 3 mm of the root apices of 11 and 12, so the root resection can be easily achieved at that level [Figure 1f].

The CBCT provided information about the hard tissues, and a putty impression was taken to record the soft tissues. The Digital Imaging and Communications in Medicine files from the CBCT images and soft tissue recordings were uploaded into a software (DDS Pro - JST sp.z.o.o. ul. Waly Dwernickiego 43/45 42-200 Czestochowa, Poland) and overlapped for the designing of the template. The template was supposed to be designed over the bone rather than the soft tissue; hence, minimum discrepancy was expected. The virtual template was then sent as a Standard Tessellation Language (STL) file and fabricated using a 3D printer [Figure 1g]. After fabricating the template, it was placed onto patient's cast, and fitting was checked. Another fitness check was performed on the patient's teeth before the surgery.

At the start of the surgery, disinfection of the skin and mucosa was carried out [Figure 2a]. The patient was anesthetized using long-acting local anesthetic agent bupivacaine hydrochloride 5.0 mg (Anawin, Neon Laboratories, Mumbai, Maharashtra, India). A crevicular incision accompanied by two vertical releasing incisions was given using a Bard-Parker number 11 and number 15 blades, respectively. A full-thickness flap was reflected using a periosteal elevator exposing the cortical bone [Figure 2b]. Disinfection of the template was performed by immersion in 2% chlorhexidine solution for 20 min. The template was placed onto the teeth and checked for stability [Figure 2c]. Any regions interfering with the seating of the template were adjusted. The bone to be cut was evaluated. The bone cutting was carried out with the help of a long shank-tapered fissure bur along the inner diameter of the template [Figure 2d]. The cut section as a block was preserved in saline for further use. Removal of the pathological tissue was done to full extent using curettes and sent for histopathological examination [Figure 2e].

Figure 2

(a) Preoperative photograph, (b) full-thickness mucoperiosteal flap, (c) placement of surgical template on the site, (d) removal of the buccal cortical plate, (e) removal of cystic lesion, (f) after root-end resection followed placement of MTA, (g) placement of platelet-rich fibrin, bone graft, and tetracycline granules, (h) placement of buccal cortical plate, (i) after suture placement, (j) suture removal after 1 week, (k) follow-up after 6 months

Apical 3 mm of the root was resected using a straight fissure bur. Root-end cavity preparation was done using endodontic ultrasonic tips (EndoSuccess, Satelec, Paris, France). The Mineral Trioxide Aggregate (MTA Angelus, Londrina, PR, Brazil) was mixed according to the manufacturer's instructions and inserted as a root-end filling material using MTA carrier [Figure 2f].

Meanwhile, platelet-rich fibrin (PRF) was derived from the patient's own blood. It was placed in the surgical defect, followed by the placement of bone graft-modified hydroxyapatite granules (G-bone, Shahjahanpur, India) and tetracycline granules (Periodontal Plus AB, Advanced Biotech Products, Tamil Nadu, India). The tetracycline granules consisted of 25 mg of collagen impregnated with 2 mg tetracycline hydrochloride [Figure 2g]. Eventually, the segment of the preserved cortical plate was positioned back [Figures 1h and 2h], and the flap was sutured with Mersilk 4.0 (Ethicon, US) black-braided nonabsorbable silk suture [Figure 2i]. In addition, a eugenol-free periodontal dressing (COE-PAK, GC, America) was applied.

The patient was recalled after 7 days for suture removal. The operating site was healing, and no postoperative symptoms or complications were noted [Figure 2j]. The pathological report diagnosed the lesion as radicular cyst. One-month, 3-month [Figure 1i], and 6-month follow-ups showed evidence of soft tissue and bone healing, and the patient was symptom-free [Figures 1j and 2k].

DISCUSSION

The objective of the apical surgery is to surgically maintain a tooth that has an endodontic lesion which cannot be resolved by conventional endodontic treatment. In addition, the periapical pathological tissue should be completely debrided by curettage to remove any extraradicular infection, foreign body material, or cystic tissue.[3] During endodontic surgery, enucleating granulation tissue in bony lesions makes the reduction of cortical bone inevitable, especially in a large apical lesion. This extensive intraoperative removal of the buccal bone plate may result in delayed healing and dehiscence of the resected roots.[5] Hence, the preservation of the buccal cortical plate is important.[6]

CBCT has unveiled the potential of 3D imaging in dentistry as an aid to improved diagnosis and treatment planning.[7] The advantages of low FOV CBCT include increased accuracy, higher resolution, scan time reduction, and dose reduction.[3] 3D scans using CT/CBCT imaging have been applied not only to the visualization of an object but also to the generation of a physical model.[8] With the aid of the 3D-printed template, minimally invasive surgical procedure minimizes the tissue injury. The template served as a carrier, carrying the information of the location of the root end and the size of the periapical lesion, the orientation and angle of the root and its apex, and the thickness of the cortical bone into the surgical procedure. This procedure enabled the surgeons to precisely remove the overlying bone and the root end.[9]

To increase the success rate of surgical treatment, it is important to maintain a good quality apical seal.[10] MTA is preferred as retrograde filling material over other materials.[11] MTA has shown the highest healing rates (91.4%) and less leakage in comparison to other materials.[1213]

To further enhance the healing of periapical defects, PRF was used.[10] PRF is an autologous concentrate of platelets on a fibrin meshwork that contains cytokines, leukocytes, and growth factors such as platelet-derived growth factor, transforming growth factor-beta, vascular endothelial growth factor, and epidermal growth factor.[14] Being autologous, it is indispensable in tissue wound healing and acts as better space filler.[15] PRF is easy to obtain and is inexpensive.

The Modified hydroxyapatite granules used in this case is noncarcinogenic, inert, easy maneuverable, dimensionally stable, and served as a scaffold for bone formation and slowly resorb to permit the formation of the new bone.[16] Tetracycline is a broad-spectrum antibiotic which is available as crystalline powder, yellow in color, acidic in nature, and primarily bacteriostatic and odorless.[17] Among the various antibiotics used for local application, tetracycline is favored due to its better resorption, protein binding capability, diffusion into tissue structures, and prolonged duration of action.[18]

The digitally designed directional template fabricated using CBCT, computer-aided design, and 3D printing technology worked in all aspects to facilitate the periapical surgery as anticipated. The root ends were accurately located using the template and resected. The surgical procedure was simplified, and the treatment efficiency was improved. However, some discrepancy between planning and execution may be anticipated if we consider the accuracy of this technology. Further studies need to be carried out to confirm the accuracy of the 3D-printed template-aided periapical surgery procedure.[9]

CONCLUSION

Meticulous planning in conjunction with technology can lead to successful treatment outcomes. 3D printing can be used in numerous innovative ways for the preservation of tissues.

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 his name and initials will not be published and due efforts will be made to conceal the identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.