Minimally invasive management of odontogenic cutaneous sinus with digitally designed endocrown: Case report with long-term follow-up

Abstract

Odontogenic cutaneous sinus tracts are uncommon manifestations of chronic dental infections, often misdiagnosed due to their resemblance to dermatological lesions. They typically originate from pulpal necrosis caused by dental caries or trauma and can be effectively managed with accurate diagnosis and adequate disinfection. This case report presents the conservative management of a mandibular second molar with extensive coronal destruction and an associated cutaneous sinus tract. Given the severe loss of tooth structure, the tooth was restored with a computer-aided design/computer-aided manufacture-fabricated zirconia endocrown using a butt joint design. Zirconia was selected for its superior fracture resistance, whereas the conservative design preserved periodontal health and provided excellent stress distribution. At 3^rd year follow-up, the tooth remained functional with no signs of reinfection, and radiographic healing was evident.

INTRODUCTION

Odontogenic cutaneous sinus (OCS) poses a significant diagnostic challenge due to its low incidence and resemblance to other cutaneous pathologies.[1] The most common etiology of OCS is a dentoalveolar abscess, arising from pulpal necrosis secondary to dental caries or trauma.[2] The resulting suppuration may usually be resorbed by the host immune mechanism. However, in some instances, it establishes drainage through the path of least resistance. This can manifest as either an intraoral sinus or, less frequently, an extraoral cutaneous sinus[3] on the chin, inferior border of the mandible, or cheek.[1] Patients seek treatment primarily for aesthetic concerns and discomfort due to pus discharge[3] which can be effectively managed by endodontic therapy.[1]

Conventionally, teeth with inadequate coronal structure were restored using postretained crowns. The disadvantages of posts are multiple appointments, increased costs, failures due to the number of adhesive interfaces, extensive preparation, and catastrophic failures such as perforation and root fracture.[4] Recent interest in minimally invasive dentistry and newer adhesive materials has led to the development of endocrowns.[5] They are conservative, single-component, monoblock ceramic crowns, functioning as both crown and a core. They achieve macromechanical retention from extension into the pulp chamber and micromechanical retention from the adhesive material.[6] The indications of endocrown are short clinical crown, extensive tooth structure loss, short root, restricted inter-occlusal space, obliterated canals, and severely curved canal.[7] The success rates of endocrowns have been reported to be 94%–100% at an average of 36-month follow-up.[8]

This case report describes a mandibular molar with extensive coronal structure loss and an associated cutaneous sinus tract secondary to dental caries, managed conservatively using a computer-aided design/computer-aided manufacture (CAD/CAM) milled endocrown, with a documented follow-up period of 3 years.

CASE REPORT

A 20-year-old male patient reported with a chief complaint of ulcer in the right lower jaw region for the past 4 months, with pus discharge and pain in the right lower back teeth region for the past 1 week. He had a noncontributory medical history. Extraoral examination revealed ulcer with suppuration and bleeding on palpation [Figure 1g]. Intraoral examination revealed grossly decayed right mandibular second molar (47) [Figure 1a], carious mandibular first molar (46), and partially erupted third molar (48). Teeth 47 and 48 were tender to percussion. Sinus tracing was performed with #25 size gutta-percha. Radiographic examination revealed periapical rarefaction in relation to 47 with sinus traced toward the apex of its mesial root [Figure 2a]. Extremely deep caries was evident in 46 without any periapical changes [Figure 2b], and the tooth exhibited exaggerated response to pulp sensibility tests (electric pulp test and cold test) compared to that to contralateral tooth (36). Diagnosis of OCS secondary to pulp necrosis and chronic periapical abscess in relation to 47, mesioangular impaction of 48, and symptomatic reversible pulpitis in 46 were made. The treatment plan consisted of nonsurgical endodontic therapy of 47, followed by surgical removal of 48, and vital pulp therapy (direct pulp capping) in 46.

Figure 1.

Clinical Images (a) Preoperative image with rubber dam isolation (b) endocrown preparation. (c) Silicone impression. (d and e) Digitally designed endocrown. (f) Computer-aided design/computer-aided manufacture fabricated Zirconia endocrown. (g) Preoperative and postoperative images showing healing of extraoral sinus opening

Figure 2.

Radiographic Images (a) Preoperative radiograph showing sinus traced toward mesial root of 47. (b) Working length determination. (c) Master cone radiograph. (d) Immediate postoperative radiograph after obturation. (e-h) 3, 9, 24, and 36 months follow-ups, respectively, showing healing of the periapical radiolucency

The treatment plan was discussed in detail, and written informed consent was obtained from the patient. Tooth was anesthetized with an inferior alveolar nerve block using lidocaine 2% with epinephrine 1:80,000 (ICPA Health Products Ltd., Andheri, India) and isolated using rubber dam [Figure 1a]. Caries excavated with round diamond bur at high speed and access gained through the pulp chamber. Chemomechanical preparation was performed with Ni-Ti rotary file (Hyflex-CM, Coltene/Whaledent, Altstätten, Switzerland) according to manufacturer’s instructions [Figure 2b]. Five milliliters of 5.25% sodium hypochlorite (Ammdent Pvt. Ltd., Punjab, India) was used as irrigant between the instrumentation. 2 ml of 17% Ethylenediaminetetraacetic acid (Prevest DentPro Ltd., Jammu, India) was used as penultimate irrigant, followed by the use of 5.25% sodium hypochlorite as the final irrigant. Water-based calcium hydroxide paste (Prevest DentPro Ltd., Jammu, India) was placed as intracanal medicament, renewed weekly for 1 month. After 2 weeks, the sinus tract was healed with no clinical signs and symptoms. Obturation of the root canals was carried out after 1 month, with gutta-percha (Coltene/WhaledentGmbh co. KG, Langenau, Germany) [Figure 2c] and zinc oxide-eugenol sealer (Prime dental products Pvt Ltd., Maharashtra, India). The tooth was then restored with a base of resin-modified glass ionomer cement (GC Gold Label, GC Corporation, Tokyo, Japan), followed by placement of a 3–4 mm thick layer of temporary restorative material (Cavit-G, 3M ESPE, Germany) to provide an effective interim coronal seal [Figures 1g and 2d].

Due to inadequate coronal tooth structure, a CAD/CAM-milled endocrown was selected as the postendodontic definitive restoration. In the third appointment, the provisional restoration was removed, and an initial 2 mm depth groove was established using a cylindrical diamond bur. This is followed by occlusal reduction with a wheel-shaped diamond to create a flat, uniform occlusal table. A circumferential supragingival butt joint cervical margin, 1–2 mm in width, was prepared to optimize adhesive bonding and marginal integrity. Pulp chamber modification included the elimination of undercuts from the pulp chamber walls using a cylindrical–conical diamond bur with approximately 7° of taper to facilitate a passive path of insertion. The intracoronal cavity depth of 3–4 mm was maintained to enhance macromechanical retention while preserving sound tooth structure [Figure 1b].

The impression of the prepared tooth was obtained with the addition of silicone impression material (Neopure, Orikam Healthcare India Pvt. Ltd.) by loading light body in the canal and putty in the tray [Figure 1c]. After setting, the impression was retrieved and scanned using extra-oral laboratory scanner (UP 360+, UP3D Tech Co., Ltd, Shenzhen). Computer-aided designing was executed using EXOCAD software (exocad GmbH, Darmstadt, Germany). While designing, undercuts in the crown were removed [Figure 1d and e]. The designed crown was then milled in the milling machine (P53, UP3D Tech Co., Ltd, Shenzhen) using Zirconia block (SHTW Aidite [Qinhuangdao] Technology Co., Ltd) [Figure 1f]. In the trial appointment, occlusion and marginal fit of the endocrown were checked, following which glazing was performed. The interim coronal seal was maintained by placing temporary restorative material (Cavit-G, 3M ESPE, Germany). In the final appointment, endocrown was cemented with dual-cure, self-adhesive resin cement (Total Cem, Itena Clinical, Villipente, France) as per manufacturer’s instructions [Figure 1g and 2e].

The tooth remained asymptomatic at 3, 9, 24, and 36 months, with the postendodontic restoration intact throughout the observation period [Figure 2e-h]. The periapical radiograph at the 24-month review demonstrated complete resolution of the periapical rarefaction [Figure 2g].

DISCUSSION

The prevalence of odontogenic sinus tracts was found to be 18.1%. Among them, intraoral sinus openings are the most common.[9] Extraoral sinus openings are often rare[10] and if present, are prevalent in the mandibular region.[11] They occur in the maxilla, if the apex of the involved teeth is superior to the muscle attachment, and in mandible, if the apex is inferior to the muscle attachment.[2] Cutaneous sinus tracts are not always associated with the source of origin.[10] Hence, it is essential to trace the sinus tract radiographically with gutta-percha or any other similar radio-opaque material. Sinus tracing and pulp sensibility tests contribute to the proper diagnosis of the OCS.[2]

The odontogenic sinus tract is lined with granulation tissue or with epithelium in advanced cases.[1] Treatments of such sinus may involve nonsurgical endodontic therapy, peri-apical surgery, or extraction. The most preferred option is nonsurgical endodontic management.[11] Effective disinfection is critical for endodontic success. In this case, 5.25% sodium hypochlorite was used for irrigation, complemented by calcium hydroxide as an intracanal medicament. The high pH of calcium hydroxide ensures prolonged antimicrobial activity, contributing to the resolution of the sinus tract and periapical pathology, as confirmed clinically and radiographically.[12] If properly diagnosed and treated, the closure of the sinus tract mostly occurs in 5–14 days.[11] In the present case, closure of the sinus tract was evident after 2 weeks of initial intervention.

Restoration of teeth with extensive coronal destruction poses a clinical challenge. Intra-coronal restoration like endocrown is a simplified, cost-effective, conservative treatment option for such teeth. These restorations can be fabricated using various materials, including metal, lithium disilicate, leucite, Polyether Ether Ketone, resin composite, zirconia, and porcelain-fused metal.[4] A recent study evaluating the mechanical behavior of different CAD/CAM fabricated ceramic endocrowns concludes that zirconia has higher fracture resistance than other ceramics and can improve the success rate of the endocrown. It stated that though catastrophic failures were common in zirconia, the load required to produce such failures has not even occurred in bruxism patients.[6] Hence, in the present case, endocrown was fabricated using zirconia.

Endocrowns were either prepared with a butt joint design or with axial reduction and a shoulder finish line. In butt joint design, the occlusal surface will be prepared parallel to the plane of occlusion, which provides a stable and wider surface for better stress distribution. The supragingival margin of the preparation preserves the marginal periodontium and produces minimal trauma while recording the impression.[13] Hence, in the present case, butt joint preparation was performed.

An effective coronal seal is also critical for the long-term success of endodontic therapy, as it prevents bacterial penetration and reinfection of the root canal system.[14] After obturation, a resin-modified glass ionomer base was placed, followed by a 3–4 mm layer of temporary restorative material to ensure an adequate interim seal. The definitive zirconia endocrown restoration was adhesively luted using dual-cure self-adhesive resin cement, which provides both micromechanical and chemical adhesion to dentin and ceramic surfaces, enhancing marginal integrity. The adhesive bonding of endocrowns creates a monoblock effect that reinforces the remaining tooth structure and reduces microleakage. Belleflamme et al.,[4] in a 10-year retrospective study, and Govare and Contrepois,[5] in a systematic review, reported excellent marginal adaptation and coronal sealing ability of resin-bonded endocrowns, comparable or superior to full-crown restorations. El Ghoul et al.[15] further confirmed that ceramic-based CAD/CAM endocrowns, including zirconia and lithium disilicate, demonstrated superior marginal and internal adaptation with clinically acceptable gaps (≤150 µm), supporting their use for predictable sealing and longevity. This adhesive, multilayered approach ensured a durable hermetic coronal seal, contributing to the tooth’s structural reinforcement and the favorable long-term outcome observed in the present case.

CONCLUSION

The successful management of an OCS requires accurate diagnosis, elimination of the source of infection, and appropriate restorative rehabilitation. In this case, the use of a zirconia endocrown not only ensured optimal sealing and functional stability but also provided durability. This highlights that conservative endodontic management combined with contemporary adhesive restorations can offer a predictable, minimally invasive, and long-term successful outcome for complex presentations such as OCS in a tooth with extensive coronal destruction.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.