INTRODUCTION:

One of the main objectives of endodontic treatment is to eradicate microorganisms from the root canal system. Numerous irritants persist within the intricacies of the canals, which cause the formation and progression of periapical lesions and continue to invade the surrounding tissues¹. The formation of the periapical lesion can be attributed to bacterial colonization and endotoxins present in the root canals. As a result of this, an inflammatory response occurs against the causative agent in the periapex².

Periapical lesions can be treated either in surgical or by non-surgical approaches. Surgical intervention has many limitations such as the medical condition of the patient, proximity to anatomical structures, and psychological trauma to the patient³. Various studies have shown a success rate of 85% - 94.4% with full and partial healing of periapical lesions following a non-surgical approach^4,5. In the literature, there is no convincing proof that mechanical instrumentation alone results in a bacteria-free root canal system. Therefore, some form of irrigation/disinfection is required to kill bacteria. Root canal therapy disinfectants can be arbitrarily divided into irrigants and intracanal medicaments (ICMs). However, in the case of periapical lesions, antimicrobial irrigants alone are insufficient to entirely eliminate the bacteria⁶. Hence, the use of inter-appointment intracanal medicaments with antimicrobial agents, which have the potential to eliminate the viable bacteria remaining in the root canal, is advocated. These agents also reduce inflammation in the periapical region, control apical exudates, and prevent or arrest inflammatory root resorption⁷. This further alleviates pain in patients.

Calcium hydroxide (CH) is a commonly used ICM that changes and destroys the lipopolysaccharides present in the cell wall of bacteria because of its high pH. The mechanism of action is through the precipitation of calcium and phosphate ions. The antibacterial efficacy could also be due to the release of highly reactive hydroxyl ions which causes DNA damage, bacterial cytoplasmic membranes, protein denaturation, and carbon dioxide absorption⁸.

Although conventional radiography is a basic and cost-effective aid to detect lesions, sometimes periapical pathologies may not be detected using it, which may lead to errors in diagnosis and management. Hence it is imperative to find a more effective and accurate method to diagnose such periapical pathologies⁹. Cone Beam Computed Tomography (CBCT) is widely used and is considered to be the gold standard for diagnosing and measuring the periapical lesion size. The main advantages of CBCT over conventional radiographs are that it can produce 3-dimensional reconstructed images in 3 orthogonal planes. CBCT can detect the roots, canals, and periapical lesion present in the tooth, and has the ability to assess the amount of expansion and destruction of cortical bone¹⁰. According to Filho et al., Periapical Index (PAI) is accepted as a valid tool for revealing changes in the extent and severity of the apical periodontitis¹¹. Cone Beam Computed Tomography- Periapical Index (CBCT-PAI) was used in this case as a tool for accurate measurement of periapical lesion size.

There are limited case studies available in the literature regarding the healing of periapical lesions evaluated using CBCT-PAI. This case report presents the non-surgical management of a large periapical lesion using CH intracanal medicament and evaluation of periapical healing using CBCT-PAI.

CASE REPORT:

A 28-year-old female patient reported with the chief complaint of pain and swelling in the lower front tooth region. History revealed trauma 3 years back due to a fall for which endodontic treatment was initiated elsewhere for 31,32,41,42 two years back. Her medical history was not contributory. Extra oral examination revealed palpable submental lymph nodes, and extra oral swelling was absent. On intraoral examination, a painful swelling of the labial vestibule and pus discharge from the periapical region of lower anterior teeth were noticed. There was a large radiolucent lesion seen in the periapical radiograph, and the affected teeth did not respond to pulp testing. A final diagnosis of previously initiated endodontic therapy with periapical abscess was made. CBCT (GALILEOS Viewer 1.8, Dentsply Sirona INC, United States) was advised, and pre-operative lesion size was measured concerning coronal (Figure 1A), sagittal (Figure 1B), and axial planes (Figure 1C) (16x13x8mm). A score of 5+D was assigned using CBCT-PAI scoring criteria (Table 1)¹². Informed consent was obtained from the patient and continuation of endodontic therapy of 31, 32, 41, 42 was planned.

After rubber dam isolation, the access cavities were modified for the affected teeth. Suppurative fluid drainage was observed. After a gentle flush with saline, working length was determined with a 15 size K file (Mani INC; Japan), and cleaning and shaping using the stepback technique was accomplished. During this time, irrigation with 5% sodium hypochlorite (Prevest Denpro Limited, India) was done during every change of instrument. CH (Ivoclar Vivadent AG, Schaan, Liechtenstein) was given as an ICM for two weeks and the process was repeated till the canals were dry. Obturation was then carried out with 2% gutta-percha points (META-BIOMED Co, Ltd, Cheongju-si, South Korea) and AH-Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland) using lateral compaction technique. The access cavities were sealed with composite (Tetric N-Ceram, Ivoclar Vivadent AG, Schaan, Liechtenstein). After a one-year follow-up, a CBCT image was taken, which showed regression of lesion in the coronal (Figure 2A), sagittal (Figure 2B), and axial planes (Figure 2C) respectively (7x7x3mm). The formation of the trabecular pattern of bone was also noted and given a score of 4 utilizing CBCT-PAI.

Figure 1: Pre-operative Cone-beam computed tomography (CBCT) scan of 31,32,41,42; (A) Coronal view; (B) Sagittal view; (C) Axial view

Figure 2: At 1 year follow-up, Cone-beam computed tomography (CBCT) scan of 31,32,41,42; (A) Coronal view; (B) Sagittal view; (C) Axial view

Table 1: CBCT-PAI Scoring criteria (Estrela et al. 2008)¹²

Score	Quantitative Bone Alterations in Mineral Structures
0	Intact periapical bone structures
1	Diameter of periapical radiolucency > 0.5–1 mm
2	Diameter of periapical radiolucency > 1–2 mm
3	Diameter of periapical radiolucency > 2–4 mm
4	Diameter of periapical radiolucency > 4–8 mm
5	Diameter of periapical radiolucency > 8 mm
Score (n)+E*	Expansion of periapical cortical bone
Score (n)+ D*	Destruction of periapical cortical bone

DISCUSSION:

Enlargement of periapical lesions occurs due to different mechanisms. This includes accumulation of osmotic fluid in lumen, proliferation of epithelial cell rests of Malassez, owing to expansion and increase in hydrostatic pressure inside the lesion and/or by other molecular means^13,14.

The advantages of using CBCT in endodontic therapy are mainly due to its high accuracy in detecting periapical pathologies even in its starting stages as well as aiding in the non-invasive differential diagnosis¹⁵. Orstavik et al. in 1986 introduced a PAI using conventional radiographs with scores ranging from healthy to severe periodontitis¹⁶. Certain limitations of this index were associated with 2-dimensional images, image acquiring technique, variations in root morphology, and bone density around the roots. All these factors would influence the sensitivity and specificity of periapical radiographs. To overcome the shortcomings of this index, Estrela et al. in 2008 introduced CBCT-PAI scoring criteria and assigned scores from 1-5, based on the size of the lesion. The main aim of this new index was to interpret high-resolution images and provide a more precise measurement of periapical lesions. The addition of variables such as expansion (E) and destruction of cortical bone (D) to the CBCT-PAI scoring system permitted better interpretation of the lesions and associated communication and prognostic accuracy¹².

In this case, the preoperative CBCT revealed a periapical lesion larger than 8 mm in size with the destruction of the cortical plate, which correspond to a CBCT-PAI score of 5+D. At one-year follow-up, the size of the lesion was reduced to a score of 4.

CH is said to be the gold standard ICM in root canal therapy because of its high pH of about 12.5-12.8. It has the potential to neutralize bacterial endotoxins, which aids in imparting antibacterial property¹⁷. The reduction in the size of the periapical lesion, with placement of CH, may be attributed to its direct effect on inflamed tissue and epithelial cystic lining, encouraging osseous repair. The antimicrobial activity of CH could be attributed to its ability to dissociate into hydroxyl ions leading to cell death of microorganisms¹⁸. Souza et al. suggested the action of CH may be due to its anti-inflammatory and anti-microbial activity, neutralization of acid products, and alkaline phosphatase activation. With these mechanisms, optimal disinfection would have been achieved even in the inaccessible areas, which in turn, promoted periapical healing¹⁹.

CONCLUSION:

In the present case report, the healing of periapical lesion was achieved using non-surgical endodontic therapy with CH intracanal medication. CBCT evaluation following one year showed a reduction in the periapical lesion size. In conclusion, a non-surgical approach should be primarily adopted for periapical lesions of endodontic origin. The use of CBCT as an adjunct diagnostic tool has also shown great results in the assessment of healing of periapical lesions.

CONFLICT OF INTEREST:

There is no conflict of interest.

ACKNOWLEDGMENTS:

We would like to thank SRM Dental College and Hospital authority, patient, and her bystanders for their cooperation.

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Received on 21.07.2021 Modified on 03.09.2021

Research J. Pharm. and Tech 2022; 15(10):4701-4704.

DOI: 10.52711/0974-360X.2022.00789