Management of Tooth and Observation of External Root Surface with Extrusion of Calcium Hydroxide-Containing Paste

1Department of Conservative Dentistry, Division of Endodontology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan 2Department of Oral Diagnostic Sciences, Division of Radiology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan 3Division of Endodontics, Department of Conservative Dentistry, Ohu University School of Dentistry, 31-1, Misumido, Tomita-machi, Koriyama, Fukushima 963-8611, Japan 4Department of Conservative Dentistry, Division of Oral Biomaterials and Technology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo 145-8515, Japan


Introduction
Extrusion of the root canal filling materials sometimes causes permanent complication. Slight to moderate overextensions with insert conventional endodontic sealers, such as gutta-percha with Grossman's sealant, often repair themselves and produce no irreversible changes with direct contact into the sinus [1]. According to the analysis of the cause of failure in nonsurgical endodontic treatment, overfilling was responsible for small portion of failure, within 3% [2]. However, Nair reported that foreign materials trapped in periapical tissue during and after endodontic treatment can perpetuate apical periodontitis persisting after root canal treatment. Foreign materials can reach the periapex, induce a foreign body reaction that appears radiolucent and remain asymptomatic for several years [3]. Foreign materials include amalgam, endodontic sealants and calcium salts derived from periapically extruded Ca(OH) 2 [4].
This case shows that extrusion of calcium hydroxide [Ca(OH) 2 ] intracanal medicament caused the persistent percussion pain.

Case Report
A 48-year-old female was referred to the Division of Endodontics, Showa University Dental Hospital. The patient had the chief compliant of occlusal pain in the right mandibular second premolar. Initially the patient received the retention procedures for stabilizing tooth position after orthodontic treatment. Before 3 months, she had received the endodontic treatment for its spontaneous pain in the right mandibular second premolar in another clinic. After several endodontic treatments,

Discussion
Calcium hydroxide has been used in endodontic therapy since 1920 when Hermann described his study [5]. The clinical effectiveness of calcium hydroxide in infected canals has been reported [6,7]. Calcium hydroxide has a high pH, and its dental use relates chiefly to its ability to stimulate mineralization, and also to its antibacterial properties [8]. A range of products has been formulated with different therapeutic actions, the effects of which are partially dependent upon the tissue to which they are applied. Nerwich reported pH changes in dentin after the root canal with calcium hydroxide [9]. After medication, the hydroxyl ions diffuse from the root canal into the surrounding, inner dentin within hours in the cervical part of the root and within days in the apical part. The hydroxyl ions have the anti-bacterial effect. Hasselgren reported that treatment with calcium hydroxide has also been shown to dissolve necrotic tissue and enhance the tissue dissolving effect of sodium hypochlorite (NaOCl) solution [10]. Many investigators reported the biocompatibility of calcium hydroxide. Histological examination was carried out to assess the biocompatibility of Calcipex II and Calcipex Plane II, new calcium hydroxide-containing pastes and these calcium hydroxide-containing pastes were revealed biocompatible [11][12][13][14]. Extended calcium hydroxide over the apical foramen contacted the periapical tissues. Rusmussen reported the calcium hydroxide direct At next appointment, a cone-beam computed tomography (CBCT; Hitachi, Tokyo, Japan) was performed with exposure parameters of 60 kV, 8 mA, 0.08 seconds was taken of the area (Figures 1B, C and D). The CBCT scan revealed the presence of periapical radiolucency and non-radiolucency root canal materials around the root apex. Periapical radiolucency was present, measuring 7 × 8 mm, along with considerable external root resorption affecting the apical region, particularly on its mesial aspect. It seems to present the external root resorption. After a total of 3 instrumentation sessions, it was decided to perform periradicular surgery of intentional replantation with apicoectomy.
After rubber dam isolation, the intracanal medication was removed, and the canal was filled with gutta-percha cones and root canal sealer (Canals N; Showa Yakuhin Kako Co. Ltd, Tokyo, Japan) by using the lateral compaction technique.
Then, the tooth was anesthetized with 1.8 ml, 20 mg lidocaine containing 0.045 mg adrenaline bitartrate (ORA ® Inj. Dental Cartridge; Showa Yakuhin Kako Co. Ltd, Tokyo, Japan) and gently extracted by dental extracting forceps. The root surface was kept moist by wrapping the root with gauze soaked in a sterilized saline.
Under the microscope, root of approximately apical 4 mm of the tooth was resected. After root-end cavity was prepared ultrasonically, SuperEBA (Bosworth Company, Skokie, IL, USA) was placed and condensed into root-end cavity preparation. The tooth was replanted and the splint was applied ( Figure 1E).
Stereomicroscopic observation showed that the root surface around apex foramen was covered with calcium hydroxide-containing paste ( Figure 2). SEM observation revealed that the surface of the root apex was covered by the extended materials and root resorption was observed ( Figures 3A and B).
At the 1-month recall appointment, the splint was removed. The patient presented asymptomatically. The mobility of the tooth was normal. The patient was subsequently followed up at regular intervals. Five months after the surgery, radiograph showed new bone formation around periapical region ( Figure 1F). The patient had no clinical symptoms of pain. contact with the connective tissue in vivo and it showed the mineralized tissues [15]. Rotstein in the case report, showed the extended calcium hydroxide was effective [14]. Holland concluded that a larger size of the apical foramen made a better contact between the material and the periapical tissue [16]. On the other side, Smith reported that extended calcium hydroxide material was not completely resorbed. If left for a long period, it induced a concentric pattern of calcification around itself similar to dystrophic calcification [11]. Therefore, it was recommended that whenever possible the material should be confined within the limits of the root canal [11,17,18]. This case suggested that the materials should be confined within the root canal. Therefore, it was considered that the extended calcium hydroxide material might cause the continuous occlusal pain for 10 months. However, other causes of persistent pain are known in apical periodontitis. The apical foramen of the case was broken, which itself can be one of persistent pain, because the excess enlargement of the apical foramen can lead the micro-fracture of the root apex, as well as persistent inflammation of periapical root tissue ( Figures 2 and 3).
In this case, the patient was referred. It was not clear when the occlusal pain occurred, before applying this paste or afterward. It was considered that the patient might already sense the occlusal pain before calcium medication unless it was used in initial preparation after pulpectomy for the extra-enlargement of root canal by the former doctor.
Physical (overfilling) and chemical (irrigants, intracanal medication, root canal filling materials) insults to the periapical tissues, can also cause apical periodontitis, depending on the severity of injury and cytotoxicity of the chemicals [19]. Foreign bodies, only themselves, such as root canal filling materials, have been shown to cause persistent periapical inflammation [20,21]. It might be considered that the calcium or other components irritated the nerve within periradicular tissue. It is possible that the foreign bodies served as carriers for the microorganism. In addition, foreign bodies have the odd property of favoring infection because they cause granulocytes to develop phagocytic defect, loss of ammunition [22]. It was considerable the excess enlargement of the apical foramen might trigger the cracks at the apical portion and the cracks caused the continuous occlusal pain.
In this case, the external absorption was seen. The resorption of root cementum and/or dentin in apical periodontitis lesions is less well understood than resorption of bone [19]. The cells responsible for dental hard-tissue resorption are called odontoclasts [23]. Its ultrastructure and gene expression are similar to those of the osteoclasts. Nevertheless, little is known about what causes odontoclast differentiation and activation to resorb dentin and cementum. Several cytokines and growth factors, such as granulocyte/macrophage RANKL, IL-1, IL-6, TNF and prostaglandins, have been shown to mediate osteoclast differentiation [24]. It might be considerable they attended the odontoclast differentiation.

Conclusion
According to the anatomical investigation, approximately 75% of teeth have canal irregularities (e.g., accessory or lateral canals) in the apical 3 mm of the tooth [24,25]. Adorno reported that in Japanese anterior maxillary teeth, a high percentage of accessory canals can be found in apical 3 mm of the root [26]. An apical resection of approximately 3 mm should include most accessory and lateral canals and thus eliminate most residual microorganisms and irritants [19]. This time approximately apical 4 mm of the tooth was resected. The area of external root resorption was removed in this case.
The root canal was already enlarged up to a size #90 with a K-file (Kavo Dental Systems Japan Co., Ltd.) by referred dentist. The mean canal width at cementodentinal junction in mandibular premolars was 0.32 mm [27]. In this case, prepared canal width at cementodentinal junction was 0.9 mm. The apical constriction was destroyed by root canal preparation. Too large apical foramen caused the extrusion of Calcipex into the periapical tissues and cracks. Appropriate size of the apical foramen was essential for success of the root canal treatment. Extruded Ca(OH) 2 paste might cause the persistent occlusal pain and the apical foramen coverage by the materials.