Preserving the Tooth from Extensive Calcification Under Magnification Using Endosonics: A Case Report

INTRODUCTION

The goal of endodontic treatment is to completely eradicate microorganisms from the root canal space and to provide a space free of microorganisms. It can be achieved by chemomechanical preparation, the use of irrigants, and intracanal medicament. Accessing the intricate anatomy of a calcified root canal is challenging for thorough cleansing and three-dimensional obturation. Calcification of the root (calcific metamorphosis) is usually seen as a defensive reaction of body’s response to trauma. Multiple factors decide the degree of calcification like the intensity of trauma, time span since the trauma occurred, body’s response.¹ The chances of perforation and excessive dentin removal are the challenges anticipated while negotiating the canal using old techniques.² So in this case report, we have used recent advances like magnification and endosonics for the successful endodontic management of mid-root calcification in the upper left central incisor.

CASE DESCRIPTION

A male patient reported to the Department of Conservative Dentistry and Endodontics at Sri Ramakrishna Dental College and Hospital with the chief complaint of pain in the upper left front tooth for the past 1 month. A history of presenting illness revealed that the patient experienced pain with a moderate intensity that was relieved on medication. The patient was symptomatic despite having received root canal treatment in the past. Medical History was non-contributory. Past dental history revealed a history of fall 5 years ago and initiated root canal therapy (RCT) in a private dental clinic in relation to 11 before 3 days. On clinical examination, the maxillary left central incisor was discolored and was with temporary restoration on palatal aspect of the crown (Figs 1 and 2). Pulp sensibility testing using a cold test revealed no response while the contralateral teeth responded positively to the test. Tender on percussion was present. Ntraoral periapical radiograph (IOPA) revealed an unusual rare calcification in the middle third of the root canal of 11 with a closed apex and widening of PDL space and intact lamina dura (Fig. 3). To assess the middle third calcification precisely CBCT images were taken. Coronal and sagittal view of CBCT revealed oblique radio-opacity that was evident in the root canal in between the junction of the apical and middle third of the root with widening of PDL space in the apical one-third of the root (Fig. 4). Radiographic diagnosis was given as calcified root canal with apical periodontitis in 11. The final diagnosis was given as root canal-treated tooth with symptomatic apical periodontitis and calcified root canal in relation to 11. The treatment plan was re-root canal treatment using magnification and ultrasonic tips in relation to 11.

MANAGEMENT

Local anesthesia was administered “2% lignocaine with 1:80,000 epinephrine.” Under rubber dam isolation and microscope, access was redefined (Fig. 5), small size K files – size 6, size 8 and pilot files were used. But resistance was felt at a distance of 19 mm from the incisal edge suggesting pulp canal calcification. Then ET25 (Acteon) ultrasonic tip was used to negotiate the calcified portion (Figs 6 and 7).

The tip was used to navigate the canal without any water, with a 10-second break and four power settings. This was done because the tip needed time to cool. After a tedious job, the canal apical to the calcification was negotiated. The initial binding file was a size of 15k file. Working length was determined using a COLTENE CanalPro™ Apex Locator and confirmed radiographically (WL – 27.5 mm). The canals were then cleaned and shaped using Protaper Gold Rotary files till F1 size (Dentsply) with continuous irrigation using 3.5% sodium hypochlorite (Prime Dental) and 17% EDTA (Prime Dental). Irrigant activation was done with an ultrasonic system (piezoelectric) during RCT. The canals were dried with paper points and calcium hydroxide was placed as an intracanal medicament. On the next visit, AH Plus sealer was coated in the canal and obturated using thermoplasticized obturation technique. Postendodontic restoration using composite was done (Fig. 8).

DISCUSSION

Dental trauma to the permanent dentition can cause clinical issues, which can be very difficult for a practitioner to address. One such issue is called calcific metamorphosis (CM), which can make it more difficult to locate the canal and obtain access in the future, making entry into the root canal system more challenging. This condition is also known as pulp canal obliteration, dystrophic calcification, diffuse calcification, and calcific degeneration. Calcific metamorphosis is defined by the American Association of Endodontists as “A pulpal response to trauma characterized by rapid deposition of hard tissue within the canal space.” The literature says that 4–24% of teeth show varying degrees of calcification due to trauma.^1–4

This is more often observed in patients who have suffered concussion or subluxation injuries. Robertson et al. found this obliteration to be either, dentin like, bone like or fibrotic in primary teeth.⁴ Lundberg and Cvek⁵ evaluated permanent maxillary incisors and found that the tissue changes were characterized by increase in collagen content and a marked decrease in the number of cells. They too found osteoid tissue with cellular inclusions adjacent to mineralized areas in pulp. The rate of deposition is uncontrolled and could be as high as 3.5 μm per day. It is not the same as pulp stones. True pulp stones are made of dentin which is lined by odontoblasts, whereas false pulp stones are formed by mineralization of pulp cells that have degenerated. Calcific metamorphosis is initiated by stimulation of odontoblastic activity. The mechanism is not known but may be due to injury to the neurovascular supply of the pulp. Another theory suggests that the bleeding in the canal and blood clot could be a focal point for calcification in case the pulp remains vital following trauma. Hence, traumatic injury to the apical blood vessels, which may not be sufficient to cause pulpal necrosis and the pulp remains vital, could lead to CM.

Many case reports have been reported on diagnosis of calcifications using panoramic radiographs, intraoral periapical radiographs, bitewing radiographs and CBCT imaging. However, CBCT imaging has been reported to increase the predictability in treating calcified canals.⁶ Radiographically loss of pulpal space, discoloration of teeth are suggestive of calcification in teeth. If such teeth are symptomatic, treatment of the following tooth comes into high difficulty class according to “American Association of Endodontists Case Assessment criteria.”⁷ The use of CBCT and dental operating microscope for the treatment of calcified canal is a boon and that is how this case was treated. Burs with long shank-like Muller burs and Munce burs are used for troughing and to locate calcified canals while ultrasonic tips are used to negotiate the calcified root canal. Multiple angulated radiograph should be taken to ensure central alignment and no loss of excessive dentin or perforation. Decalcifying, chelating agents and irrigants should be used during biomechanical preparation to soften canal dentin and facilitate passage of file like 17% EDTA gel and 17% EDTA irrigant. In this case report, ET 25 (Acteon) tip was used which has titanium and nobium that allows perfect transmission of the ultrasonic vibrations and tip flexibility. It was 25 mm long that allowed it to reach the apical third. It must be recognized that the byproduct of ultrasonic energy is heat. So while performing longer periods of time under endosonics, the field should be frequently flushed with water to decrease heat buildup and the potential for dangerous heat transfer to the attachment apparatus.⁸ The middle third calcification was not visible with the naked eye but with the power of microscope, the calcification was clearly visible and negotiable. The microscope is not only used to get visual enhancement but also to improve ergonomics. However, the tooth was saved from extensive calcification by interrupting the process of calcific metamorphosis. Follow-up after 6 months showed successful outcome.⁹

CONCLUSION

Full apical disinfection is essential for the prognosis and efficacy of RCT. A dental operating microscope procedure, different file systems, irrigants, chelating agents, customized burs, and other strategies can be used to successfully treat calcified teeth in cases when negotiation is possible.

ORCID

Remya Varghese https://orcid.org/0000-0002-5661-084X

REFERENCES

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