| Abstract|| |
Aim: The aim of the study was to compare the fracture resistance of roots obturated with mineral trioxide aggregate (MTA) obturation with post, MTA apical plug with Resilon obturation, MTA apical plug with gutta percha (GP) obturation, complete MTA obturation in teeth with wide open apex.
Materials and Methods: Fifty freshly extracted human maxillary central incisors were selected. Teeth were divided into four experimental groups (n = 10) and one control group (n = 10). Fifty teeth were separated, and roots of each tooth were standardized to a length of 12 mm. Access opening was done and instrumented with ProTaper F2 passed beyond the apex. The canals were then irrigated with 17% ethylenediaminetetraacetic acid and 3% sodium hypochlorite. Calcium hydroxide was placed in the canals for 7 days. The specimens were then divided into five groups. Group I: Apical plug MTA with metal post, Group II: Apical plug MTA with Resilon, Group III Apical plug MTA with GP, Group IV: Complete MTA obturation, and Group V: Control group. Fracture strength was measured using Instron testing machine at a speed of 5 mm/min, and the data were statistically analyzed using ANOVA and t-test.
Results: The roots reinforced with metallic post and MTA (Group 1) has the higher fracture strength when compared with other groups (P < 0.05).
Conclusion: This Ferro-concrete reinforcement technique of MTA with the metallic post can be used in cases with wide open apex to increase the fracture resistance of tooth.
Keywords: Ferro concrete, fracture resistance, mineral trioxide aggregate, obturation, Resilon
|How to cite this article:|
Rosaline H, Rajan M, Deivanayagam K, Deepthi M. Ferro-concrete reinforcement of endodontically treated teeth with wide open apex. Indian J Dent Res 2015;26:276-9
Pulp necrosis of an immature tooth caused by trauma, caries or other pulpal pathosis will necessitate endodontic treatment that can pose both endodontic and restorative challenges because of incomplete closure of the apex and thin dentinal walls. Earlier management of open apices in pulpless immature teeth was accomplished through apexification using calcium hydroxide therapy. The long-term exposure to calcium hydroxide may weaken the dentin, and thus making the roots more susceptible to fracture. Various studies have proved mineral trioxide aggregate (MTA) as an alternative to calcium hydroxide for apexification. Endodontically treated immature teeth have a relatively high incidence of cervical root fracture either spontaneously or due to minor impacts. Various materials such as gutta percha (GP), Resilon, composite, MTA were used in obturating root canal with a wide open apex, which increased the fracture resistance of teeth.
|How to cite this URL:|
Rosaline H, Rajan M, Deivanayagam K, Deepthi M. Ferro-concrete reinforcement of endodontically treated teeth with wide open apex. Indian J Dent Res [serial online] 2015 [cited 2020 Sep 22];26:276-9. Available from: http://www.ijdr.in/text.asp?2015/26/3/276/162888
MTA is used as an apical plug to overcome the disadvantages of calcium hydroxide. It is also used as a sealer, obturating material, pulp capping agent, perforation, and furcation repair. This material has demonstrated good sealability, biocompatibility, induce hard apical tissue formation in immature teeth and has antibacterial properties. Based on the properties of civil engineering and taking into account that immature teeth are prone to fracture, Bortuluzzi in 2007 used metallic post with MTA in bovine teeth and concluded that MTA and metallic post increased the fracture resistance of immature bovine teeth.
Hence, the purpose of the study was to compare the fracture resistance of roots obturated with MTA apical plug followed by GP obturation, MTA apical plug with Resilon obturation, MTA obturation with stainless steel post, and complete MTA obturation in human teeth with wide open apex.
| Materials and Methods|| |
Forty-five extracted maxillary central incisors were selected and stored in saline until use. The teeth were examined under ×4 to discard teeth with carious lesions, cracks, and fractures. The roots of each tooth were standardized to a length of 12 mm as measured from the apex to the facial cementoenamel junction by cutting off the root end. To prevent dehydration, the teeth were stored in saline until use. Coronal access was done, and the working length was determined. Canals were instrumented with k-files till size 50 and then shaped using ProTaper S1-S2-F1-F2 to the working length. The apical foramen was shaped to 80 ISO by extruding ProTaper F2 exactly 9 mm from the apex. After instrumentation, the root canals were irrigated with 3% sodium hypochlorite solution and 17% ethylenediaminetetraacetic acid (EDTA) to remove the smear layer. Calcium hydroxide was placed in the canals as an intracanal medicament, and the access was sealed with Cavit. All the teeth were stored at 37°C and 100% humidity. After 7 days, the calcium hydroxide was removed by instrumentation, and the canals were flushed with 3% sodium hypochlorite solution and 17% EDTA. The canals were dried with paper points. The teeth were divided into four experimental groups and one control group.
- Group 1: MTA obturation with the metallic post
- Group 2: MTA apical plug with Resilon obturation
- Group 3: MTA apical plug with GP obturation
- Group 4: MTA complete obturation
- Group 5: Control group (no obturation).
White MTA (Angelus Industria de Produtos Odontologicos ltda, Londrina, PR, Brazil) was mixed, according to manufacturer's instructions and condensed to the root canals that were coated with MTA sealer (Angelus) with the help of messing gun and hand pluggers. A metallic post (stainless steel-Reforpost L Angelus Industria de Produtosn Odontologicos Ltd.) of 7 mm length was inserted into the canal through the MTA. The posts were placed in such a way that their long axes were aligned with the long axis of the teeth and with no contact to the root canal walls. Excess material was sheared off, and moist cotton was placed in the coronal access cavities and temporized with cavit. Post adaptations were checked by digital radiography. After 24 h, the access was restored with composite, and the specimens were stored at 37°C for 48 h.
Five mm of an apical plug of white MTA was placed in all the ten teeth with the Messing Gun and compacted to the apical area with a hand plugger wrapped around with a moistened cotton pad. The uniformity of the plug was radiographically checked.
After 24 h, Resilon cones (Pentron, Wallingford, CT) with Epiphany sealer (Pentron) were used for the obturation in this group. Root canals were coated with epiphany sealer with Lentulo spiral and obturation was completed. Excess material was sheared off and condensed vertically with the plugger. After this procedure, the material in the root canal was cured with visible light for 30 s. Canal openings were sealed with composite, and the specimens were stored at 37°C for 48 h.
Five mm apical plug was placed in the similar way in all the ten teeth and radiographically confirmed. After 24 h, root canals were coated with AH plus sealer, and obturation was done with GP using lateral compaction technique. Radiographs were made to, and canal openings were sealed with composite, and the specimens were stored at 37°C for 48 h.
White MTA was mixed according to manufacturer's instructions, and inserted into the entire root canal with MTA sealer applied on the walls and checked radiographically. Moist cotton was placed in the coronal access and temporized with cavit. After 24 h, the canal openings were then sealed with composite, and the specimens were stored at 37°C for 48 h.
The control group had no root canal filling done in it.
The roots of each tooth were embedded in polyvinyl impression material and were mounted in an acrylic resin to simulate the periodontal ligament. A jig was then fabricated to fit each tooth. An Instron universal testing machine was used to apply a load to each specimen at a speed of 5 mm/min. The load was applied on the occlusal surface of the prepared teeth at the long axis of the root. The peak load to fracture was recorded, and the statistical analysis was completed using a one-way ANOVA and t-test.
| Results|| |
Roots reinforced with metallic post and MTA (Group 1) has the higher fracture strength when compared with other groups [Table 1]. MTA complete obturation (Group 4) and roots obturated with Resilon (Group 2) were nearly similar in their fracture resistance and the least resistant among the treated groups was the roots that were obturated with MTA apical plug and GP (Group 3) (P < 0.05).
| Discussion|| |
Apexification is defined as a method to induce a calcified barrier in a root with an open apex, which requires special attention and treatment. The loss of both coronal and radicular tooth structures along with decreased moisture content as a result of endodontic treatment will increase the likelihood of fractures during functional loading and are responsible for 38% of reduction in flexural strength of crowns., The weakening of dentin after the calcium hydroxide placement for a longer time may be due to the proteolytic capacity of calcium hydroxide. This leads to weakened tooth structure with thin dentinal walls and the remaining tooth structure prone to fracture.
MTA can be placed in one appointment, saving months of treatment time compared to calcium hydroxide apexification., MTA demonstrated the highest fracture resistance at 1-year. It prevented the destruction of the collagen matrix in the root dentin, thereby preventing loss of physical properties.
Functional and parafunctional vertical and oblique forces of teeth are replicated in various studies. About 90° forces were applied to the long axis of the teeth, which exhibited the highest failure load in the cast post and core group Thus, in this part of our study, we have used vertically applied forces perpendicular to the long axis of teeth.
There is a consensus that posts do not strengthen the root, but change the stress distribution along the root and put the tooth at higher risk of fracture. The results of the present study show the roots reinforced with Metallic post has the higher fracture strength when compared with other groups, and the least resistant to the treatment groups are the roots that were obturated with GP/AH plus sealer [Table 1].
GP being the standard obturating material in the root canal treatment does not reinforce endodontically treated roots owing to its inability to achieve an impervious seal along the dentinal wall of the root canal. It does not chemically bond to the dentinal wall and does not form a monoblock because the sealer does not bind to GP (Manzoor et al. 2010).
Root canals obturated with Resilon a thermoplastic synthetic polymer with Epiphany sealer resulted in higher fracture resistance when compared to roots obturated with GP and AH Plus sealer. This could be due to the removal of smear layer by EDTA, which allows the root canal filling material and the sealers to contact the canal wall thus increasing the penetration into the dentinal tubules. Resilon also has an improved flexural strength and in conjunction with a resin-based sealer it offers improved bonding potential by forming a monoblock (Manzoor et al. 2010).
MTA has been proved to be a good alternative to the long-term use of calcium hydroxide. Obturation with MTA has got a good herpetic seal and induces hard apical tissue formation in immature teeth. MTA induces the expression of TIMP-2 in the dentin matrix thus increasing the fracture resistance of the tooth. MTA has been used for reinforcement of immature teeth. The sealing ability, biocompatibility, and dentinogenic activity of MTA are attributed to the release of calcium and its ability to form hydroxyapatite.
Bortoluzzi introduced an intraradicular reinforcement technique with a postembedded in MTA mass in bovine teeth. The concrete for constructions is constructed using portland cement, which is strong in compression but weak in tension. Reinforcement with iron or steel increased the concrete strength in tension. Thus, a reinforced concrete combines the tensile strength of metal and compressive strength of concrete to withstand a heavy load. This reinforced concrete is termed as Ferro-Concrete., In our study, the stainless steel metal post in MTA, which is similar to portland cement in concrete, reinforces the tooth in compression, as well as tension, thus, increasing the fracture resistance of the tooth with wide open apex.
To prevent corrosion problems in between post/MTA interface, stainless steel post with high resistance to oxidation has been used., Thus, in cases of roots with wide open apices and thin dentinal walls, MTA with the post can be used in a single appointment to increase the fracture resistance of teeth.
| Conclusion|| |
This Ferro-concrete reinforcement technique of MTA with the metallic post can be used as a single step procedure for apexification and reinforcement in cases with wide open apex.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Department of Conservative Dentistry and Endodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu
Source of Support: Nil., Conflict of Interest: None