Resurrecting an unsalvageable lower incisor with a mono-block approach.

Contemporary techniques, as well as the availability of bioactive and adhesive materials in endodontics, have helped revivifying teeth that were deemed hopeless. These newer materials and techniques would enable the clinician: (a) to predictably stop microbial activity (b) to achieve a total corono-apical fluid tight seal and (c) to strengthen mutilated teeth by obtaining intra-radicular reinforcement through mono-block effect. This case report demonstrates the successful treatment of a mutilated anterior tooth with the use of bioactive and adhesive materials to obtain a total seal and mono-block effect. This article also shows the use of a simple method in the placement of root filling cement into the root canal.

INTRODUCTION

Almost always, it is the patient's wish to retain their natural tooth, especially if it is the anterior. It is said to give the patient a more positive body image and self-worth.[1] In addition, extraction of the teeth is generally undesirable and should be considered as the last resort because of the limitations in alternative prosthodontic replacement.[2] The satisfaction obtained and the trust created between a patient, and a dentist can be huge if a tooth that was considered hopeless can be successfully saved. Patient's desire to save his/her natural tooth should however not compromise the overall treatment result.[3] Hence, thorough understanding of the risks involved and the prognosis of various treatment options available is important. This should be discussed with the patient before initiating the treatment.[4]

Contemporary equipments and techniques can improve root canal treatment outcomes for challenging cases.[5] The success of root canal therapy is dependent on the factors mentioned. All these three aspects have undergone a tremendous change in modern endodontics with the introduction of newer dental equipments and the advances in material science, concepts, and techniques. The developments in the form of bioactive and adhesive materials, as well as the techniques that facilitate mono-block effect can enhance the positive outcome and promote greater success in endodontic cases that were considered to have a poor prognosis. The purpose of this paper was to present a case where contemporary endodontic materials are used to obtain mono-block effect and corono-apical fluid impervious seal. The case also demonstrates the use of a simple method in the placement of the bioactive cement into the root canal.

CASE REPORT

A 25-year-old male patient reported to the Department of Conservative Dentistry and Endodontics with a chief complaint of pus discharge from the labial sulcus in relation to lower anterior. There was no associated pain, although patient gave a history of trauma during childhood for which exact age was not reported by the patient. The patient also gave no history of any treatment for the same. The patients' medical history was noncontributory.

Intraoral examination revealed grossly decayed and discolored lower right central incisor (#41). The pulp chamber of the tooth was open to the oral cavity. A sinus opening with associated pus discharge was found in relation to the labial mucosa of the particular tooth [Figure 1a]. Radiographic examination revealed the presence of an unusual radiopaque linear object in the cervical third of the root canal of #41 and was associated with a periapical radiolucency [Figure 1b]. On further history, taking the patient revealed a habit of placing sharp objects within the root canal whenever the pain was experienced. However, he could not recall any incidence of lodgment of a metallic object within the root canal. A diagnosis of chronic periradicular abscess associated with foreign body lodgment was made. The patient was advised to undergo the retrieval of the foreign object followed by endodontic therapy and postendodontic restoration. The treatment plan was explained to the patient and consent was obtained.

Figure 1

(a) Mutilated lower right central incisor with an associated sinus tract (#41) (b) intraoral periapical radiograph showing a metallic foreign object within the root canal (tubular canal with open apex and peri-radicular radiolucency can be appreciated) (c) retrieved foreign objects from the canal

Caries and debris were removed, and remaining tooth structure was assessed. On the inserting no. #10 K-file (Dentsply Maillefer, Ballaigues, Switzerland) the foreign object could be easily bypassed. As the object was located in the cervical third of the tooth and lack of remaining tooth structure a conservative braiding file approach for retrieval was planned. Three H-files (Dentsply Maillefer, Ballaigues, Switzerland) were inserted into the canal, twisted around the object to engage it and were pulled coronally. This dislodged the foreign object from the canal. A wooden object was also retrieved along with the metallic object, which was not visible radiographically [Figure 1c]. Working length was determined, and root canal shaping and cleaning were performed. The root canal was irrigated alternately using 1% sodium hypochlorite (Novo Dental Products Pvt. Ltd., Mumbai, India) and 17% EDTA (B.N. Laboratories, Mangalore, India) with agitation. Calcium hydroxide (Calcicure™, Voco and Cuxhaven, Germany) was carefully placed into the radicular space for around a month for thorough disinfection. However, the sinus opening failed to heal. This necessitated the need for surgical intervention.

A full thickness mucoperiosteal flap was elevated, the granulation tissue removed and the bony crypt was then irrigated with povidone iodine (PVI) solution (Ramadine® Solution, Raman andWeil Pvt. Ltd., Mumbai, India). The root was not further resected due to the already compromised crown root ratio. The presence of dehiscence of the buccal cortical plate was noted, but no fracture was evident on the root surface. With the flap open, the canal was irrigated with normal saline and dried with sterile paper points (Dentsply Maillefer, Ballaigues, Switzerland). Biodentine®(Septodont, St. Maurdes Fossés, France) was placed at the apical region via the orthograde approach. A custom-made delivery system was used for placing biodentine into the root canal. The delivery system was made using two surgical needles that fitted snugly into each other. We used a 16 gauge needles as the barrel and 18 gauge for preparing the plunger. A diamond disk was used to cut the thinner needle (18 gauge) to remove the bevel and leave behind a needle of 21 mm length, the thicker needle (16 gauge) was cut to a length of 10 mm [Figure 2a]. The thinner needle was carefully sealed with cyanoacrylate to block the lumen. The excess cyanoacrylate on the outer surface of the needle was carefully removed with an absorbent. The plunger was inserted into the barrel to check for proper fit and smooth movement of the plunger into the barrel [Figure 2b]. Biodentine was mixed according to the manufacturer's instruction. The thicker needle (barrel) was tapped on the mixed mass of biodentine to fill the lumen of the needle and was then placed at the orifice of root canal and held between the thumb and middle finger. The thinner needle was used as a plunger and pushed with the index finger to place biodentine into the root canal [Figure 2c]. The material was condensed using endodontic hand pluggers. The delivery and condensation steps were repeated until a 5 mm thickness of the plug was achieved. The result was confirmed radiographically [Figure 2d]. The biodentine root filling was maintained approximately 5 mm apically to provide space for intra-radicular retention and reinforcement of remaining tooth structure through fiber post. After final condensation, a moist cotton pellet was placed in the canal to aid in the complete setting of material from both sides. The canal was then temporized, and the flap was replaced and sutured to the position.

Figure 2

(a and b) Device assembly used in the placement of biodentine (c) Full thickness mucoperiosteal flap was raised to debride the lesion and to down-pack Biodentine®(d) intraoral periapical radiograph shows well condensed apical plug of Biodentine®

After 5 days, the sutures were removed. Postspace was then prepared and a prefabricated glass fiber post (Mirafit White, Hager and Werken; Duisburg, Germany) was placed and cemented using a self-adhesive resin cement Rely X-Unicem (3M ESPE St Paul, MN, USA) as per the manufacturer guidelines [Figure 3a]. This was followed by composite resin core build up (3M ESPE St Paul, MN, USA). Following 4 weeks recall visit, tooth #41 was found asymptomatic, and sinus tract had completely healed. The tooth was then restored with porcelain fused to metal crown [Figure 3b]. Radiographic evaluation of the area of intervention after a year showed increased bone density suggesting of progressive healing [Figure 3c].

Figure 3

(a) Placement of a prefabricated glass fiber post immediately after suture removal (b) after cementation of the final prosthesis (c) 1-year postoperative radiograph showing resolution of the periapical lesion

DISCUSSION

The first step for a successful outcome in endodontic therapy is an effective decontamination of the root canal system. It is achieved with the use of mechanical instruments and chemical agents, which includes root canal irrigants and intra-canal medicaments.[6] In the present case, the contents dislodged within the immature root canal was initially removed to facilitate thorough root canal disinfection. As the preservation of the remaining thin radicular dentin was important, and since the foreign object could easily be bypassed, file braiding or multiple file technique was employed to engage and dislodge it.[7] Along with the metallic object, by chance, a wooden piece lodged within the root canal was also retrieved. Ultrasonic systems were not used as it has the potential to push the foreign body beyond the open apex and thus can further complicate the situation.

The canal was then disinfected using sodium hypochlorite with passive ultrasonic agitation. This was done to remove the necrotic debris and disrupt the endodontic biofilm.[8] Root canal shaping using endodontic files was avoided, so as to preserve the remaining radicular dentin. Irrigation with EDTA was also performed to remove the smear layer. Following this calcium hydroxide intra-canal medicament was employed to eliminate the remaining microorganisms.[9] However, this disinfection protocol failed to show signs of healing as evident from the persistent sinus tract even after 1-month of therapy. Hence, surgical treatment was opted for exploration and debridement of the periradiclar area. The granulation tissue was curetted out, and the bony crypt was disinfected with PVI solution. PVI was used as it demonstrated good antibacterial property[10] and effective hemostyptic and antiedematous action.[11]

After thorough disinfection, the next step for achieving predictable endodontic treatment outcome is a fluid tight seal to prevent reinfection and entomb remaining microorganisms within the root canal. In the current case, the root canal was obturated with calcium silicate based endodontic cement, Biodentine®. This material possess specific bio-properties such as biocompatibility, biointeractivity (ion-releasing, i.e., the release of biologically relevant ions), and bioactivity (apatite-forming ability); and can thus promote the formation of new periapical bone.[12] It is also shown that calcium silicate-based cements (CSC) adhere to root dentine, in the presence of tissue fluid by the formation of an interfacial layer resembling hydroxyapatite in structure and composition by a biochemical process termed as biomineralization.[1314] Formation of intratubular tags in conjunction with the interfacial mineral interaction layer referred to as the “mineral infiltration zone,” have been demonstrated with the use of CSC.[15] Studies have shown that biodentine is superior to its counterpart mineral trioxide aggregate (MTA) in terms of sealing ability.[16] This could be attributed to its' pronounced ion release allowing the formation of more calcium phosphate deposits.[12] Another advantage of biodentine is its faster setting time (12–15 min) when compared to MTA (170 min). Hence, the incidence of degradation or even washing away of the cement from the surgical site ought to be lesser than MTA.[17] This fast setting tricalcium silicate-based material was introduced orthograde into the canal using a custom-made delivery system. The orthograde method of biodentine placement circumvented the limitation of inaccessibility of placing a retrofilling and allowed a denser compaction and easy removal of extruded material after compaction. The custom endodontic cement carrier is inexpensive, autoclavable and allows the predictable placement of material endodontic cements into inaccessible areas within the root canal. The limitation of this device is the difficulty of its use in narrow and/or curved canals.

The third and the final step for the predictable outcome for endodontic treatment is the reinforcement of the remaining radicular and coronal dentin. The use of biodentin and fiber post demonstrated the highest fracture resistance of simulated immature teeth that had been backfilled using different materials in a study by Topçuoglu et al.[18] The creation of a mono-block unit within the root canal either by an endodontic material or with a postcore system is said to protect remaining tooth structure or prevent root fractures.[19] Primary mono-block (i.e., a single interface between the material and the root canal wall) formed with the use of tricalcium silicate-based material is shown to distribute the stresses better.[19] Once the apically placed biodentin was set, the remainder of the root canal was reinforced using a glass fiber posts because it has an elastic moduli comparable to that of dentin and has the ability to satisfactorily bond to this substrate by the use of adhesive cement.[20] The adhesive cement used here was Rely X™ Unicem, a self-adhesive resin cement that has good chemical interaction with the calcium in hydroxyapatite, improving their mechanical properties.[21] The secondary mono-block (i.e., have two circumferential interfaces) attained allows the better stress distribution and can thus reduce the risk for root fractures.[1922] The mono-block thus created can reinforce the remaining dental tissue, as well as create a fluid tight seal, throughout the entire length of the root canal.

CONCLUSION

Creating a mono-block and achieving a complete corono-apical fluid tight seal with the use of adhesive materials in endodontics can be considered in resurrecting teeth that are ill-fated. The fast setting CSC used for filling the radicular space in the current case has shown a very favourable result. This could be attributed to its' enhanced biocompatibility, biointeractivity, and bioactivity. Thus, it can be said that the contemporary materials available in the market can now improve root canal treatment outcomes for perplexing cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.