Cone beam-computed topographic evaluation of a central incisor with an open apex and a failed root canal treatment using one-step apexification with Biodentine™: A case report.

A symptomatic endodontically treated immature tooth with periapical pathology presents multiple challenges to the clinician. Owing to incomplete root formation, gutta percha removal has to be done carefully without further damaging the periapical tissue or pushing the obturating material beyond the apex. Nonsurgical approach toward treating such a tooth would necessitate the creation of an apical barrier followed by conventional root canal treatment. Current literature suggests one-step apexification with mineral trioxide aggregate (MTA), with an apical matrix as the treatment of choice. A new calcium silicate-based cement also called as dentine substitute by the manufacturers with good handling properties has been introduced recently by the trade name Biodentine™ (Septodont, St. Maurdes Fossés, France). This case report presents management of a secondary endodontic case with an open apex treated with the concept of 'lesion sterilization and tissue repair (LSTR)' using triantibiotic paste and Biodentine™ for apical barrier formation. A 12-month follow up with cone beam-computed topography (CBCT) exhibited progressive involution of periapical radiolucency with indications of good healing of the periapical tissues and absence of clinical symptoms.

INTRODUCTION

The incidence of traumatic injury to young permanent anterior teeth exceeds that of both dental caries and periodontal disease.[1] Management of these teeth poses a great challenge to the clinician as incorrect treatment at the time of trauma can lead to further worsening of the situation and development of periapical lesion.[2]

Traditionally, calcium hydroxide has been the material of choice for apexification, but it is slowly phasing out because of evolution of better and newer biomaterials and due to its inherent shortcomings.[3] Single-step apexification involves nonsurgical compaction of a biocompatible material into the apical end of the root canal, thus, creating an artificial apical stop that allows immediate filling of the root canal.[4] Numerous biomaterials have been reported in various studies like triantibiotic paste, freeze-dried bone, osteogenic protein 1, and mineral trioxide aggregate (MTA)[5678] that have been used for obtaining root end closure. In the present case, a new calcium silicate-based bioactive restorative cement Biodentine™ was chosen for apexification because of its superior physical properties like setting time, solubility, and easy handling characteristics. Disinfection of the root canal was carried out with triantibiotic paste due to its better performance on calcium hydroxide-resistant microorganisms that are more prevalent in retreatment cases like the present one. This case report presents the management of a symptomatic secondary endodontic case with blunderbuss canal and a periapical lesion in a single setting apical barrier placement using Biodentine™ and healing was analyzed using cone beam-computed topography (CBCT).

CASE REPORT

An 18 year-old male patient presented with the chief complaint of pain and discolored upper front tooth. He had incurred trauma to the teeth due to a fall from a two-wheeler motor vehicle more than 10-years ago and underwent endodontic treatment followed by crown immediately after the trauma for the maxillary right central incisor. Patient was symptomless for sometime but in due course developed periodic swelling and now since 6 months had noticed intermittent pus discharge. On consulting another dentist, endodontic treatment for the right lateral incisor was started but as the pain was progressively increasing, so the patient was referred by the dentist to the college. The patient's medical history was noncontributory and vital signs were within normal limit.

Intraoral examination revealed the presence of porcelain fused to metal crown in right maxillary central incisor associated with a sinus tract in the periapical region. Tracing of the sinus tract with gutta percha confirmed the involvement of the central incisor. The tooth was tender on percussion and palpation. The periodontal status was normal (probing depth <3 mm) with no mobility ruling out any periodontal pathology. The lateral incisor showed incompletely done root canal treatment. Radiographic examination of the central incisor revealed poorly obturated root canal with incomplete root formation. The root end had thin dentinal walls with apical flaring and periapical rarefaction of 2-3 mm [Figure 1]. The lateral incisor had intact periodontal ligament space and showed complete root formation. Electric and cold tooth vitality testing were performed for all the maxillary anterior teeth except the maxillary right central incisor. The right lateral incisors gave a negative response and all the other teeth gave a positive response. According to the clinical and radiographic findings, there were two treatment options available for the central incisor, either a surgical removal of the periapical lesion followed by retrograde filling or a nonsurgical endodontic retreatment with apexification. Taking into consideration the current guidelines, a more conservative nonsurgical approach was chosen as the line of treatment.

Figure 1

Preoperative radiograph

Treatment protocol

The tooth was anesthetized by 2% lidocaine with 1:100000 adrenaline followed by the removal of the crown. The reasons for the removal of crown were poor aesthetics and marginal gap between the crown margin and the finishing line. After isolation with rubber dam, access was gained in the central incisor with Endo Access Bur (Dentsply Maillefer, Ballaigue, Switzerland) with water spray. There was frank purulent discharge from the tooth once the pulp chamber was reached. Gutta percha removal was carried out with H-files [Figure 2]. Working length was estimated by an apex locator (Root ZX mini- J Morita MFG. Corp. Kyoto, Japan), but due to inconsistent reading, an additional intraoral periapical radiograph (IOPAR) was also taken for confirmation. Access cavity modification and working length determination were also carried out for the lateral incisor. Minimal instrumentation of the central incisor with manual K-files # 140 (Beutelrock, Munchen, Germany) was carried out with a light parietal action to avoid further weakening of the already thin dentinal walls along with passive irrigation with 10 ml of 3% sodium hypochlorite and 2% chlorhexidine solution (Sigma Chemicals, St. Louis, MO, USA) alternatively with sterile saline. Irrigation was carried out with side-vented irrigation needles (R C Twents irrigation needle, Prime Dental Products Pvt. Ltd, Mulund Mumbai) keeping them 1 mm short of the radiographic apex and no attempt was made on shaping the canal. Furthermore, irrigants were activated with Endoactivator (Dentsply, Maillefer, Ballaigues, Switzerland) tip size 5× (large 35/04) at a speed of 10.000 cpm with 2-3 mm vertical pumping action keeping the tip 2 mm short of apex without damaging the apical tissue, for the removal of pulpal remnants, debris, and remnant bacteria. The aim was introduction of the irrigant deeper into the dentinal tubules, lateral canals, and inaccessible areas. The canal was dried with a large size paper point and an intracanal dressing of triple antibiotic paste containing minocycline, ciprofloxacine, and metronidazole (100 μg each ml−1) with propylene glycol as vehicle was packed 1 mm short of the radiographic apex. The access cavity was temporarily sealed with resin-modified glass ionomer cement (Fuji II LC, GC, Bonneuil sur Marne, France) and the patient was recalled after 2 weeks. The shaping and cleaning of the lateral incisor was completed with rotary NiTi files (Protaper, Dentsply, Maillefer, Ballaigues, Switzerland) up to size F-2 and RC prep (Premier Dental Products, Norrstown, PA, USA) as a lubricant. A total of 2% chlorhexidine gel was placed as an intracanal medicament in the lateral incisor.

Figure 2

IOPAR after crown and gutta percha removal of 11. IOPAR = Intraoral periapical radiograph

After 2 weeks, when the patient was asymptomatic. The tooth was again anesthetized and isolated followed by removal of intracanal dressing with copious irrigation and ultrasonic files. The canal was flushed with 10 ml of 3% hypochlorite followed by 10 ml of sterile saline and dried with absorbent paper points. Biodentine™ (Septodont, St. Maurdes Fossés, France) was manipulated according to manufacturer's recommendation and placed in the apical one-third of the root canal with the help of Micro Apical Placement system (Dentsply, Maillefer, Ballaigues, Switzerland). It was condensed into the canal with plugger to create an apical plug of 5 mm and was left undisturbed for 15 min. The lateral incisor was obturated using lateral condensation technique with AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) and restored. The hardness of the apical plug was checked with an endodontic plugger and the remaining portion of the canal was sealed using thermoplastic gutta percha (DiaGun, DiaDent Group international, Chungcheongbuk-do, Korea) [Figure 3] and restored. Follow up clinical examination after 3 weeks showed complete healing of the sinus tract and absence of any clinical symptoms. The patient was recalled for checkup after 1 year, and IOPAR [Figure 4] and CBCT [Figure 5a-c] was advised. Both showed progressive involution of periapical radiolucency and healing with a calcific barrier at the apex.

Figure 3

Immediate post obturation radiograph

Figure 4

Follow up radiograph after 12 months showing resolution of the periapical lesion

Figure 5

(a) CBCT vertical section view. CBCT = Cone beam-computed topography. (b) CBCT sagittal section view. CBCT = Cone beam-computed topography. (c) CBCT horizontal section view. CBCT = Cone beam-computed topography

DISCUSSION

The present case shows successful management of a failed endodontically treated immature permanent tooth with periapical lesion. Revascularization was not attempted in the present case as it was already root canal-treated tooth and present literature regarding regenerative therapy in secondary endodontic cases is scarce. Furthermore, previous endodontic procedure could have damaged SCAP (stem cells from apical papilla) or vital mature pulp cells, which play a critical role in regeneration by acting as a source of odontoblast and are responsible for the root maturation.[9]

Disinfection of the root canal is of prime importance for a successful apexification. Because this was a case of failed root canal, the choice of intracanal medicament was triple antibiotic paste.[10] Calcium hydroxide was avoided due to the predominance of calcium hydroxide-resistant microorganism like Enterococcus faecalis and Candida species found in secondary endodontic cases. ‘Lesion sterilization and tissue repair (LSTR)’ therapy, which is based on the concept of thorough disinfection leading to suppression of root canal pathogens allowing better healing of periapical tissues was followed in the present case. It suggests the use of triple antibiotic paste, for better disinfection and healing in oral tissues.[11] An in vitro study on minimal inhibitory concentration for ciprofloxacin, minocycline, and metronidazole found that triple antibiotic paste (100 μg each ml−1) was effective in inhibiting the growth of all strains of Enterococci family suggesting its use in persistent endodontic cases.[12] Madhubala et al., also reported a reduction of up to 98.4% colony forming units with triple antibiotic paste in comparison with 59.4% with calcium hydroxide in E. faecalis-infected root canals.[10]

MTA is among the most popular material for apexification because of its osteoconductive properties, biocompatibility, sealing ability, and hydrophilic nature. But some of its drawbacks include its technique sensitivity, long setting time, difficulty in compaction, and nonbonding to tooth.

Biodentine™ is a new bioactive dentine substitute based on “Active Biosilicate Technology” recently been introduced in 2011. It is biocompatible, has mechanical properties similar to dentin, and has good sealing ability on dentinal surfaces.[13] In a recent in vitro study comparing microleakage of glass ionomer cement, MTA, and Biodentine™, it was found to exhibit least microleakage when used as a retro-filling material.[14] It also forms a chemicomechanical bonding with tooth and composite, reinforcing the thin fragile immature roots unlike MTA.[13] Its short setting time (9-12 min) is attributed to the smaller particle size, addition of calcium chloride as accelerator, and reduction in amount of liquid required for setting.[13]

According to ‘modified internal matrix concept’, the use of collagen while placement of MTA has been suggested by Bargholz to prevent its extrusion into periapical area that may result in persistence of inflammation complicating or preventing the healing of the tissues.[15] Calcium chloride improves its consistency, making its compaction in the canal more controlled, avoiding the need of a matrix, and reducing the chances of going beyond the apex, making it safer and more operator friendly than MTA. Additionally, its insolubility in saliva and ability to withstand pressure of 400 gm mm−2 within 6 min of setting makes it ideal for single visit apexification negating the need for a second appointment for obturation.[13]

Hard tissue healing that is closely affected by alkaline pH and calcium ion release of materials was found to be similar for both Biodentine™ and MTA when used as a root end filling material.[16] Furthermore, an in vitro study comparing root canal dentinal uptake of calcium and silicon from MTA and Biodentine™ found it to be higher for the latter.[17]

There has been a paradigm shift not only in the treatment approach of immature permanent tooth with open apex but also in method of evaluation of healing of periapical pathologies. Although conventional radiograph was showing satisfactory healing, CBCT was advised, as extremely small bone changes like bone formation and resorption are more precisely evaluated by it during follow up periods than the former.[18] Because we were evaluating a new material, a three-dimensional evaluation by CBCT was advised to further substantiate the periapical healing as concluded in a recent case report.[19]

The conclusion drawn from the present case report need to be further validated with longer prospective studies with Biodentine™. The physical properties require to be researched furthermore as most of the data is given by the manufacturer. Owing to great variations among existing clinicians in regards to treatment of these failed endodontic cases, there is a need for formulation of a treatment protocol for retreatment cases with open apices. There are few studies on Biodentine™ apexification, so more studies are required for further validation of the predictability regarding use of this new material. A longer follow up is, however, necessary to ensure success of the treatment.

CONCLUSION

A combination of correct case selection, stringent disinfection protocol, and precise and controlled placement of a barrier at the apex can lead to better periapical healing with a nonsurgical apexification procedure. Biodentine™ can be a good alternative to MTA for creation of an apical barrier, as its placement is simpler for the operator and cost-effective for the patient.