|Year : 2014 | Volume
| Issue : 3 | Page : 152-155
Management of tooth with failed regeneration procedure
Swati Bhosale, P Mridula, M Rameshkumar, S Jayasree
Department of Conservative Dentistry and Endodontics, Government Dental College, Calicut, Kerala, India
|Date of Web Publication||18-Dec-2014|
Department of Conservative Dentistry and Endodontics, Government Dental College, Calicut, Kerala
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Teeth with immature root development, necrotic pulps, and apical periodontitis present multiple challenges for successful endodontic treatment. Regenerative endodontics is a contemporary approach to managing these problems. Successful regeneration depends on a race between the new tissue and bacteria populating the pulp space and on the ability of the patient to heal the dental pulp tissues. Importance of prevention of bacterial entry into the root canal and maintaining proper coronal seal should not be overemphasized. Evidence suggests that mineral trioxide aggregate (MTA) apexification may be more beneficial for severely injured teeth than a regenerative endodontic procedure. Fiber posts, in combination with composite resin or with accessory fiber posts, can be recommended alternative to cast post and core in flared roots, due to the lower risk of catastrophic failures and better stress distribution. It is the tactic of choice for reinforcing structurally weakened roots as the function, and the prognosis of the restored root is improved, compared with the use of one single, inadequately fitting post. This report is about a case with failed regeneration procedure and managed with MTA apexification and multiple fiber posts to enhance its fracture resistance of maxillary central incisor.
Clinical Relevance To Interdisciplinary Dentistry
- Mineral trioxide aggregate apexification may be more beneficial for severely injured teeth than a regenerative endodontic procedure
- Large diameter posts contribute more favorably to the fracture resistance of the root postcore-crown system than small diameter posts
- Fiber posts, in combination with composite resin or with accessory fiber posts, can be recommended alternative to cast post and core in flared roots, because of the lower risk of catastrophic failures and better stress distribution.
Keywords: Accessory post technique, mineral trioxide aggregate apexification, regeneration
|How to cite this article:|
Bhosale S, Mridula P, Rameshkumar M, Jayasree S. Management of tooth with failed regeneration procedure. J Interdiscip Dentistry 2014;4:152-5
| Introduction|| |
Traumatic injuries to permanent teeth are more common in children in the age group of 8-10 years. , Dental trauma causes damage to the tooth ranging from enamel infarction to crown-root fracture to loss of tooth due to avulsion.
Trauma to immature permanent tooth may lead to loss of pulp vitality, pulpal necrosis that will prevent the root formation. The treatment of pulpal necrosis in an immature tooth with an open apex presents a unique challenge to the dentist. The absence of an apical constriction makes root canal treatment difficult because of the inability to obtain a seal with conventional obturation techniques. The thin root canal walls render it susceptible to fracture. 
Regenerative endodontics is a contemporary approach to managing this problem. In other words, in a case with an immature apex and necrotic pulp, regenerative endodontics allows for continued root development, thicker dentinal walls, longer root length, and a closed apex, thus reducing the risk of fracture during tooth function. This approach is based on the presence of osteo/odonto progenitor stem cells in the apical papilla that are resistant to the infection and necrosis caused by proximity to periodontal blood supply.  In this treatment, the ideal goal is to prepare an appropriate environment inside the root canal space (i.e., absence of bacteria and necrotic pulp tissue, presence of a scaffold and a good coronal seal) that promotes repopulation of these stem cells, regeneration of pulp tissue, and continuation of root development.  There are several case studies that demonstrate successful clinical and radiographic outcome for this treatment approach in single rooted , and molar teeth. ,
However, there are several drawbacks and unfavorable outcomes of regenerative endodontic procedures,  which include discoloration of the tooth, time required for disinfection of the root canal space with triple antibiotic paste or calcium hydroxide and increased number of clinical sessions (compared with one-visit mineral trioxide aggregate [MTA] apical barrier technique).
In some studies, the outcome of regenerative endodontic treatments of necrotic immature teeth was lower than ideal, including absence of increase in root length, , absence of increase in root canal wall thickness,  or lack of formation of tooth apex.  This case report discussed about a case of failed regeneration procedure and managed with MTA apexification and multiple fiber posts to enhance its fracture resistance of maxillary central incisor.
| Case report|| |
A young 13-year-old male patient reported to the department of conservative dentistry and endodontics with the chief complaint of broken, discolored tooth in upper front region and foul smell occasionally. Medical history of the patient was not contributory. History revealed that the patient had a history of trauma 5-6 years back and underwent regeneration procedure for the same tooth 3 years back [Figure 1]a and b and tooth discolored after treatment. Clinical examination showed middle third crown fracture and discoloration of tooth no. 11 with loss of coronal seal [Figure 2]a. Radiographic examination showed incompletely closed root apex, insufficient root length and relatively wide canal with incomplete filling of the canal and dislodged coronal seal [Figure 1]a. Reinforcement of the root with anatomical fiber post along with MTA apexification to achieve apical seal and to strengthen the root was planned and written informed consent was obtained.
Under rubber dam isolation tooth no. 11 was opened and filling from the canal was removed with no. 35 H file (Dentsply Maillefer, Ballaigues, Switzerland). Stop was observed at the apex on instrumentation suggestive of calcific barrier due to previous regeneration procedure, which was incomplete and even larger files could penetrate the barrier (No. 45, No. 50 H file [Dentsply Maillefer, Ballaigues, Switzerland]). Working length was determined by using radiographic method and paper point method. Primary focus was given to the chemical disinfection of the canal due to reduced dentin thickness. Irrigation was done with 5.25% sodium hypochlorite (Novo Dental Product, Pvt. Ltd., Mumbai, India), and side vent needle to avoid the possibility of extrusion of irrigant. 2% Chlorhexidine solution (Safe Plus Neelkanth Healthcare Pvt. Ltd,. Rajasthan, India) is used as final irrigant after intermittent irrigation with saline. Canal was dried using paper points. Triple antibiotic paste made up of ciprofloxacin 500 mg (Ciplox 500 mg, Cipla Ltd., Sikkim, India), metronidazole 400 mg (Aristogyl, Aristo Pharmaceuticals Pvt. Ltd., India) and minocycline 100 mg (Ranbaxy Laboratories Ltd., Solan, India) was placed as an intracanal medicament because of its antimicrobial efficacy. Patient was recalled after 21 days [Figure 1]c. Canal was irrigated with normal saline for removal of triple antibiotic paste and with 5.25% sodium hypochlorite. 3-4 mm MTA (ProRoot MTA Dentsply, Tulsa, OK USA) was placed as an apical barrier to achieve adequate apical stop and reduce the further possibility of bacterial leakage into the periapical area as well as to strengthen the apical 3 rd of root [Figure 1]d.
An impression of postspace was made using light body and putty consistency addition polyvinyl silicone impression material. A study model was prepared from the impression. Master fiber post (size 3) and two accessory fiber posts (size 1) (superpost CONICO ESTRIADO, Exceldent Trading Quezon city) were selected to adapt the canal configuration on study model. In the following appointment, fit and adaptability of the selected posts were verified clinically. Selected fiber posts were etched with 37% phosphoric acid (Vococid Voco cuxhaven, Germany) and after application of bonding agent (Tetric N- Bond Ivoclar Vivadent) posts were bonded to each other by resin cement (3M ESPE Rely X TM U100, Germany) similar to rolled gutta-percha technique [Figure 2]b. Small amount of composite (3M ESPE Filtek TM , USA) was built up on these fiber posts unit to compensate remaining space at coronal third of the canal [Figure 2]c. This anatomical post was again etched, silane coupling agent (monobond plus, Ivoclar vivadent) and bonding agent was applied and the unit was cemented into the canal [Figure 1]e. Core build up was done with composite up to coronal third of crown. All ceramic full crown restoration was placed in order to satisfy patient's aesthetic needs [Figure 2]d and e.
|Figure 1: (a and b) IOPA showing previous regeneration procedure and lack of coronal seal. (c) Radiograph after disinfection with triple antibiotic paste. (d) Mineral trioxide aggregate is placed as an apical barrier. (e) IOPA showing multiple fiber posts in position|
Click here to view
|Figure 2: (a) Clinical photograph showing fractured and discolored central incisor due to previous regeneration procedure. (b) Selected master fiber post and two accessory fiber posts bonded into single unit. (c) Composite build down was done on customized fiber post to follow canal configuration. (d) Placement of all ceramic crown. (e) One year follow-up|
Click here to view
| Discussion|| |
Regeneration is the ideal desirable outcome for any restorative procedure. The last decade has seen a quest for a material that can regenerate the odontogenic tissue successfully, both from a periodontal and endodontic aspect. Regeneration of the pulpal tissue of an infected immature tooth with apical periodontitis had once been thought to be impossible. However, if a suitable environment could be achieved, that is, absence of intracanal infection and presence of a scaffold conducive to tissue in growth, then regeneration of pulp might take place. In the present case failure of regenerative procedure can be attributed to poor coronal seal and bacterial contamination of the root canal. And also the suggested fact is the success of regenerative endodontic procedure is dependent on the ability of the patient's immune system to heal the dental pulp tissues. 
Some recent limited evidence suggests that MTA apexification may be more beneficial for severely injured teeth than a regenerative endodontic procedure.  MTA offers the option of two-visit apexification procedure, which has the benefit of better compliance and reduced number of radiographs, particularly in younger patients. In the present case, it was found that the barrier formed was incomplete, porous, and even the larger files were able to penetrate through it into periapical area. Root wall thickness was not increased, and root length was inadequate. Hence, MTA barrier was placed to achieve fluid tight seal in the apical portion of the root canal and to strengthen the root canal walls in the apical portion of the canal.
To solve the problem of thin root canal walls and to restore the tooth function based on concept of rolled cone technique of gutta-percha, selected master fiber post and accessory posts were bonded to each other and made it into a single unit following the canal configuration. Finally, this configured post was cemented with uniform layer of resin cement into the canal.
Fiber post was selected overcast post as they are more flexible than metal posts, modulus of elasticity (stiffness)  is same as dentin and distribute forces more evenly in the root, resulting in fewer root fractures. 
Anatomically adapted fiber post will have added benefits, thickness of the cementing medium is minimal and constant  thus reducing polymerization stress caused by a great amount of cement around the post ,, and also formation of bubbles or voids, representing areas of weakness within the material, is less likely in a thin and uniform layer of cement.  The thin and constant thickness of the cement layer, combined with the absence of voids, increase the retention of the post, thus reducing the tendency to debonding.  Thick posts contribute more favorably to the fracture resistance of the root-post-core-crown system than thin posts, presuming that excess preparation and subsequent weakening of the remaining root dentin is at the same time avoided.  In fact, the load-bearing capacity is not only related to the strength of the adhesive interfaces, but also to the design of the postsystem in simulating the structure of the tooth.  So in the present case, preference was given to anatomic post.
There is a linear relationship between fracture load and the diameter of posts.  The greater thickness of the coronal portion of the anatomically adapted post could preserve the margin on the tension side from opening during cyclic load and the margin on the compressive side from crushing cement and dentin, maintaining marginal integrity under function. Faria et al. evaluated the effect of fiber postrelining with composite resin on push-out bond strength. Relined fiber posts presented higher retention values than the nonrelined ones. All failures occurred at the interface between resin cement and root dentin. 
The MONOBLOC philosophy must be expandable, with techniques and products to accommodate the wide, flared canal, while also considering the other existing variables, such as C-Factor and S-Factor stress,  polymerization shrinkage and even microleakage.
The C-Factor and S-Factor (stress associated with polymerization shrinkage) are at their highest with postcementation, because of the high number of involved surfaces and no unbounded surfaces.  With this anatomical post, if any polymerization shrinkage of composite occurs, it will be at the free space and not in between the tooth and the restoration, neutralizing the S-Factor effect. The cement thickness will be minimal and uniform. ,
| Conclusion|| |
It is possible to conclude that use of the fiber post, associated with accessory posts is the method of choice for reinforcing structurally weakened roots and provides an improvement in the load carrying ability of the restored root is validated, as opposed to the use of one single inadequately fitting post.
| References|| |
Andreasen JO, Ravn JJ. Epidemiology of traumatic dental injuries to primary and permanent teeth in a Danish population sample. Int J Oral Surg 1972;1:235-9.
Bastone EB, Freer TJ, McNamara JR. Epidemiology of dental trauma: A review of the literature. Aust Dent J 2000;45:2-9.
Ding RY, Cheung GS, Chen J, Yin XZ, Wang QQ, Zhang CF. Pulp revascularization of immature teeth with apical periodontitis: A clinical study. J Endod 2009;35:745-9.
Huang GT, Sonoyama W, Liu Y, Liu H, Wang S, Shi S. The hidden treasure in apical papilla: The potential role in pulp/dentin regeneration and bioroot engineering. J Endod 2008;34:645-51.
Hargreaves KM, Giesler T, Henry M, Wang Y. Regeneration potential of the young permanent tooth: What does the future hold? J Endod 2008;34:S51-6.
Petrino JA, Boda KK, Shambarger S, Bowles WR, McClanahan SB. Challenges in regenerative endodontics: A case series. J Endod 2010;36:536-41.
Chueh LH, Huang GT. Immature teeth with periradicular periodontitis or abscess undergoing apexogenesis: A paradigm shift. J Endod 2006;32:1205-13.
Nosrat A, Seifi A, Asgary S. Regenerative endodontic treatment (revascularization) for necrotic immature permanent molars: A review and report of two cases with a new biomaterial. J Endod 2011;37:562-7.
Cehreli ZC, Isbitiren B, Sara S, Erbas G. Regenerative endodontic treatment (revascularization) of immature necrotic molars medicated with calcium hydroxide: A case series. J Endod 2011;37:1327-30.
Nosrat A, Homayounfar N, Oloomi K. Drawbacks and unfavorable outcomes of regenerative endodontic treatments of necrotic immature teeth: A literature review and report of a case. J Endod 2012;38:1428-34.
Chen MY, Chen KL, Chen CA, Tayebaty F, Rosenberg PA, Lin LM. Responses of immature permanent teeth with infected necrotic pulp tissue and apical periodontitis/abscess to revascularization procedures. Int Endod J 2012;45:294-305.
Murray PE, Garcia-Godoy F. Hierarchy of aging effects in human premolars. Todays FDA 2004;16:16-9.
Güzeler I, Uysal S, Cehreli ZC. Management of trauma-induced inflammatory root resorption using mineral trioxide aggregate obturation: Two-year follow up. Dent Traumatol 2010;26:501-4.
Lanza A, Aversa R, Rengo S, Apicella D, Apicella A. 3D FEA of cemented steel, glass and carbon posts in a maxillary incisor. Dent Mater 2005;21:709-15.
Adanir N, Belli S. Stress analysis of a maxillary central incisor restored with different posts. Eur J Dent 2007;1:67-71.
Grandini S, Goracci C, Monticelli F, Borracchini A, Ferrari M. SEM evaluation of the cement layer thickness after luting two different posts. J Adhes Dent 2005;7:235-40.
Braga RR, Ferracane JL. Alternatives in polymerization contraction stress management. Crit Rev Oral Biol Med 2004;15:176-84.
Ferracane JL. Developing a more complete understanding of stresses produced in dental composites during polymerization. Dent Mater 2005;21:36-42.
Miguel A, de la Macorra JC. A predictive formula of the contraction stress in restorative and luting materials attending to free and adhered surfaces, volume and deformation. Dent Mater 2001;17:241-6.
Eick JD, Gwinnett AJ, Pashley DH, Robinson SJ. Current concepts on adhesion to dentin. Crit Rev Oral Biol Med 1997;8:306-35.
Boudrias P, Sakkal S, Petrova Y. Anatomical post design meets quartz fiber technology: Rationale and case report. Compend Contin Educ Dent 2001;22:337-40, 2, 4.
Lassila LV, Tanner J, Le Bell AM, Narva K, Vallittu PK. Flexural properties of fiber reinforced root canal posts. Dent Mater 2004;20:29-36.
Bell AM, Lassila LV, Kangasniemi I, Vallittu PK. Bonding of fibre-reinforced composite post to root canal dentin. J Dent 2005;33:533-9.
Standlee J, Caputo A. Biomechanics. J Calif Dent Assoc 1988;16:49-58.
Faria-e-Silva AL, Pedrosa-Filho Cde F, Menezes Mde S, Silveira DM, Martins LR. Effect of relining on fiber post retention to root canal. J Appl Oral Sci 2009;17:600-4.
Breschi L, Mazzoni A, De Stefano Dorigo E, Ferrari M. Adhesion to intraradicular dentin: A review. J Adhes Sci Technol 2009;23:1053-83.
Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M. Self-adhesive resin cements: A literature review. J Adhes Dent 2008;10:251-8.
[Figure 1], [Figure 2]