Dental Traumatology 2015; 31: 250–254; doi: 10.1111/edt.12150
Resistance to leakage of various thicknesses of apical plugs of Bioaggregate using liquid filtration model € u ba Bezgin1, € l Memis € l1, Tug Betu ß Ozg 2 Cem S ß ahin , S ß aziye Sarı1 1 Department of Pediatric Dentistry, Faculty of Dentistry, Ankara University; 2Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey
Key words: apexification; apical barrier; Bioaggregate; mineral trioxide aggregate Correspondence to: Betul Memis Ozgul, Department of Pediatric Dentistry, Faculty of Dentistry, Ankara University, Besevler, Ankara, Turkey Tel.: 905363156948 e-mail: [email protected] Accepted 24 September, 2014
Abstract – Aim: The aim of this study was to compare the resistance to leakage of different thicknesses of Bioaggregate (BA) and 4-mm-thick white mineral trioxide aggregate (WMTA) in an apexification model using liquid filtration. Methods: 32 extracted mandibular premolar teeth were sectioned at the cemento-enamel junction and 3–4 mm from the tooth apex to obtain 12-mm-long root segments. The apical and coronal thirds were prepared with size two through six Gates Glidden burs. The teeth were divided into four groups according to material and thickness, as follows: Group 1: 2-mm BA; Group 2: 4-mm BA; Group 3: 12-mm (total length) BA; Group 4: 4-mm WMTA (control). The empty parts of the roots in Groups 1, 2, and 4 were filled with gutta-percha and root canal sealer, and leakage was measured using fluid filtration. The data were analyzed using the Kruskal–Wallis H-test. Results: No statistical differences in microleakage were observed between Groups 1, 2, and 4 (P > 0.05). Group 3 (roots filled completely with BA) showed significantly less leakage than the other groups tested (P < 0.01). Conclusions: The findings of this study showed that 12 mm of BA exhibited the best resistance to leakage. At the same time, 2–4 mm of BA showed similar results when compared to 4-mm MTA. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used as an apical barrier for apexification.
Immature permanent incisors with open apices may develop pulp necrosis usually as a result of trauma. Endodontic treatment of a non-vital tooth with an immature apex poses a particular challenge for the clinician. Although pulp regeneration treatment is growing in popularity, several studies have reported regenerative endodontic treatment of necrotic immature teeth to result in less-than-ideal outcomes (1–3). Nosrat et al. (4) reported a possible relationship between duration of pulp necrosis and treatment outcome, suggesting that long-standing infection might destroy cells capable of pulp regeneration. When regenerative treatment has failed or not considered as an option, apical barrier techniques are still used quite often in the treatment of such teeth (5, 6). The procedure entails closing the open apex with a biological material that acts as an apical barrier to permit immediate filling of the root canal (7). An ideal root-end filling material should be biocompatible, resist leakage, be antibacterial, have tissue-regeneration capacity, and should be easy to prepare and handle (8). Mineral trioxide aggregate (MTA) has good sealing ability and has demonstrated good success in one-visit apexification (9–12). Numerous studies have shown an apical plug of 3–5 mm to be sufficient for apical barrier techniques (13–16). However, MTA also has a number of disadvantages, such as crown discoloration (17, 18), 250
extended setting time (19–21), high costs (22), and difficulties in manipulation (23, 24). In addition, the findings on MTA’s biocompatibility are controversial, ranging from very good (24–26) to less favorable compared to other materials related to a discharge of cytotoxic ingredients such as aluminum and bismuth (27–29). Given these drawbacks, the search for an ideal root-end filling material is ongoing. Bioaggregate [(BioAggregate, Verio Dental Co. Ltd., Vancouver, Canada) (BA)] is a new material that has recently been introduced to the market as an alternative to MTA for use in perforation repair and vital pulp therapy and as a root-end filling material (30–32). BA has shown antibacterial effects (33) and sealing ability (34) comparable to that of MTA, and the absence of aluminum and bismuth in BA has resulted in a reported biocompatibility greater than that of MTA (29, 32, 35). Despite these positive characteristics, BA has not been sufficiently evaluated for its effectiveness in apical barrier techniques (36). Therefore, this in vitro study aimed to compare the microleakage using liquid filtration of different thicknesses of BA used as apical rootend fillings for apexification and to compare those with 4-mm MTA apical plugs that are commonly used in dental practice. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Resistance to leakage of apical plugs of BA Materials and method Specimen preparation
The study was conducted using 32 single-rooted human mandibular premolar teeth with mature apices and with no root caries, root fracture, or resorption that were extracted for orthodontic/periodontal reasons. The crowns were sectioned at the cemento-enamel junction (CEJ) using a diamond disk, and the apical portions were then sectioned to obtain standardized roots, 12 mm in length. Intracanal tissues were extirpated using a barbed broach (Medin Barbed Broach, Vlachovicka, Cezch Republic). To ensure a standardized blunderbuss shaping of the specimens the apical and coronal thirds (4 mm) were enlarged with Gates Glidden burs (GG, Antaeos, VDW GmbH, Munich, Germany) number 2–6 with a low-speed handpiece, the preparations were considered completed when a size 6 GG bur moved through the preparation without pressure. Following the preparations of apical and coronal thirds (4 mm), the middle thirds were instrumented using K-Flexofiles (G-star Medical Co., Ltd, Guangdong, China) up to a master file size of 80. The canals were irrigated between instruments with 2 ml of 5% sodium hypochlorite (NaOCl) and after instrumentation with 5 ml of 5% NaOCl, 5 ml of distilled water, 5 ml of 17% ethylenediaminetetraacetic acid (EDTA, Pulpdent Corporation, USA), and 5 ml of distilled water as a final rinse. The irrigation procedures were performed using a 27gauge needle; for each irrigation solution, a separate dental injector needle was used. The needle was placed in the coronal part of the teeth, and gentle pressure was applied during the irrigations. The canals were dried with paper points. Even though the same preparation procedures were followed for all teeth, radiographs were used to ensure that the canal walls had a conical blunderbuss shape that showed apical and coronal parts of the teeth were flared from the middle part mimicking the shape of young permanent teeth. The teeth were pressed into moisturized floral foam (Oasis Floral Foam, Kent, OH, USA) to simulate oral conditions and mimic the adaptation of periapical tissue during obturation. The teeth were then randomly divided into four groups, as follows: Group 1. (2 mm BA) (n = 8): The apical 2 mm were filled using Bioaggregate (Verio Dental Co. Ltd., Vancouver, Canada) mixed according to the manufacturers’ recommendations. The material was placed in the canals using the MTA Gun System (Dentsply, Maillefer, Switzerland) and then compacted using endodontic pluggers that were marked to the desired level of fill. Periapical radiographs of specimens were taken to control the level of fill. Group 2 (4 mm BA) (n = 8): The apical 4 mm were filled using BA as described above. Periapical radiographs of specimens were taken to control the level of fill. Group 3 (12 mm BA) (n = 8): The entire canal length (12 mm) was filled using BA as described © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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above. Periapical radiographs of specimens were taken to control the level of fill. Group 4 (4 mm MTA)(control group) (n = 8): The apical 4 mm were filled using white MTA (ProRoot MTA, Dentsply, Maillefer, Switzerland) mixed according to the manufacturers’ recommendations. Material was placed in the canals using the MTA Gun System (Dentsply, Maillefer, Switzerland) and then compacted using endodontic pluggers that were marked to the desired level of fill. Periapical radiographs of specimens were taken to ensure the level of fill. The length of the teeth from the radiograph was measured and proportioned by the real length (12 mm standard for each specimen), and the level of the fill was measured using the same proportion. To allow root-end filling materials to set completely, root segments were wrapped in wet gauze and placed in an incubator at 37°C for 96 h at 100% humidity. The setting of the material was gently checked by introducing a size 80 gutta-percha cone into the canal and tapping it with finger pressure. When the proper hardness was confirmed, cold lateral compaction technique was used with gutta-percha points to fill the unfilled root segments of specimens in Groups 1, 2 and 4. An ISO size 80 master cone (DiaDent, Almere, Netherlands) coated with AH-Plus Sealer (Dentsply, Maillefer, Switzerland) was inserted into the canal and lateral compaction with size 20 and 25 gutta-percha points was performed using finger spreaders size 30,25, and 20 (Dentsply, Maillefer, Switzerland). The compaction process was performed until the spreader sized 20 no longer penetrated to the coronal third of the canal (37). Periapical radiographs of specimens were again taken to ensure a complete fill. Root segments were again wrapped in wet gauze, placed in an incubator at 37°C for 24 h to allow complete set of the filling materials. Evaluation of leakage
Microleakage was evaluated using a modified version (38, 39) of the fluid transport method originally developed by Pashley et al. (40). The root specimens were attached to a hydraulic plastic tube and the connections of the specimen and tube were coated with epoxy resin (Pattex; Henkel, D€ usseldorf, Germany). The parts of the filtration model (tubes, micropipette, buffer, and etc.) were all filled with deionized water. To pass in a tiny air bubble, a microsyringe was inserted in the micropipette, and water was drawn back. The air bubble and the system were stabilized to locate the bubble in a suitable position within the micropipette. Regulated air from a pressure tank at 1240 cm H2O was applied from the apical aspects of the specimens, forcing water through any voids along the filler–canal interface. The linear displacement of the air bubble within the tube was measured over 10 min and converted to volume displacement expressed as ll 9 min 1 9 cmH2O 1. Fluid transport results were analyzed with SPSS statistical software (Version 11.5; SPSS Inc, Chicago, IL, USA) using the Kruskal–Wallis H-test.
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€ ul et al. Memisß Ozg€ This study found complete root filling with BA (12 mm) to provide statistically superior sealing when compared to 2- and 4-mm BA and 4-mm WMTA apical plugs. The results also showed 2-mm and 4mm BA and 4-mm WMTA to possess similar sealing properties. After initially producing a mechanical seal, MTA continues to dissolve, resulting in the formation of hydroxyapatite crystals that react with dentin to create a chemical adhesion (49). The fact that BA contains hydroxyapatite may explain the similarities in leakage results between BA and WMTA observed in the present study. Leal et al. (34) used glucose leakage to evaluate the sealing ability of WMTA and BA and, in line with our results, found no statistically significant difference between WMTA and BA. An in vitro study by Martin et al. (13) found the mean fluid conductance of 3- to 5-mm WMTA orthograde apical plugs to be 4 9 10 1 ll 9 min 1 9 cmH2O 1, which is higher than that of the 4-mm WMTA and 2mm and 4-mm BA groups in the present study (mean 1 9 10 2 ll 9 min 1 9 cmH2O 1). The difference may be explained by the fact that Martin et al. obturated the root canal space beyond the MTA apical plug with gutta-percha, but without a sealer, whereas in the present study, the roots were obturated with gutta-percha followed by a sealer. Tuna et al. (36) investigated the fracture resistance of immature teeth filled with BA and ProRoot MTA and found superior fracture resistance when BA was used for root filling. Considering that BA has shown biocompatibility superior to that of MTA (29, 32, 35) and good biomineralization (50) in addition to the sealing ability found in the present study, BA may be considered a promising material for use in trauma-induced endodontic treatment of teeth with immature apices;
Results
Fluid conductance values (mean standard deviation) are shown in Fig. 1. Specimens completely filled with BA showed the least amount of leakage (P < 0.01); however, there was no statistically significant difference between microleakage among any of the other groups (P > 0.05) (Table 1). Discussion
Filling materials developed for use in endodontics require good sealability to reduce bacterial leakage. Several studies have shown MTA to possess good sealability (41–45), but no study could be found that compared BA to WMTA in this regard. Studies on the use of MTA as apical plugs showed that MTA in thickness levels of 3–5 mm to be sufficient for apexification techniques (13–16). Valois and Costa (42) stated a 4 mm of MTA as a root-end filling was significantly more effective than lesser amounts in preventing dye leakage. Considering that, in this study, 4-mm WMTA apical plugs were used as control to compare with different thickness levels of BA. To mimic clinical conditions, this study used an apical barrier model, with roots shaped to a blunderbuss and the space above the apical plug obturated with gutta-percha and a root canal sealer. The fluid transport model developed by Pashley et al. (40) has been reported to provide a non-destructive method of quantitatively measuring microleakage around coronal restorations and endodontic retrograde fillings (46). This study used a modified version (38, 39) that has been reported to be more sensitive than bacterial penetration and conventional dye penetration methods used to measure microleakage (47, 48).
Fig. 1. Fluid conductance values of the BA Groups and WMTA Group.
Table 1. Statistical values of apical plugs used in the study Leakage
BA 2 mm BA 4 mm BA 12 mm MTA 4 mm
Kruskal–Wallis H
n
Mean
Median
Min
Max
Standard deviation
8 8 8 8
0.00988 0.01025 0.00050 0.00963
0.01000 0.01100 0.00000 0.00950
0.00800 0.00800 0.00000 0.00800
0.01200 0.01200 0.00200 0.01200
0.00146 0.00149 0.00093 0.00160
H
P
18.474
0.000
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Resistance to leakage of apical plugs of BA however, long-term prospective clinical trials of this material are needed. Conclusion
The findings of this study showed that BA exhibited better results when used as 12-mm plugs compared to 2- to 4-mm plugs, which showed similar results when compared to 4-mm MTA that is used routinely in dental practice. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used for apical barrier techniques. Acknowledgement
The authors would like to thank Prof. Dr. Zafer C ß ehreli for his contribution to this study. Disclosures
We affirm that we have no financial affiliation (e.g., Employment, direct payment, stock holdings, retainers, consultantships, patent licensing arrangements, or honoraria), or involvement with any commercial organization with direct financial interest in the subject or materials discussed in this manuscript, nor have any such arrangements existed in the past 3 years. References 1. Petrino JA, Boda KK, Shambarger S, Bowles WR, McClanahan SB. Challenges in regenerative endodontics: a case series. J Endod 2010;36:536–41. 2. 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. 3. 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. 4. 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. 5. Damle SG, Bhattal H, Loomba A. Apexification of anterior teeth: a comparative evaluation of mineral trioxide aggregate and calcium hydroxide paste. J Clin Pediatr Dent 2012;36:263–8. 6. Jeeruphan T, Jantarat J, Yanpiset K, Suwannapan L, Khewsawai P, Hargreaves KM. Mahidol study 1: comparison of radiographic and survival outcomes of immature teeth treated with either regenerative endodontic or apexification methods: a retrospective study. J Endod 2012;38:1330–6. 7. Rafter M. Apexification: a review. Dent Traumatol 2005;21:1–8. 8. Gartner AH, Dorn SO. Advances in endodontic surgery. Dent Clin North Am 1992;36:357–78. 9. Torabinejad M, Pitt Ford TR, McKendry DJ, Abedi HR, Miller DA, Kariyawasam SP. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endod 1997;23:225–8. 10. Shabahang S, Torabinejad M. Treatment of teeth with open apices using mineral trioxide aggregate. Pract Periodontics Aesthet Dent 2000;12:315–20.
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Resistance to leakage of various thicknesses of apical plugs of Bioaggregate using liquid filtration model € u ba Bezgin1, € l Memis € l1, Tug Betu ß Ozg 2 Cem S ß ahin , S ß aziye Sarı1 1 Department of Pediatric Dentistry, Faculty of Dentistry, Ankara University; 2Department of Prosthodontics, Faculty of Dentistry, Hacettepe University, Ankara, Turkey
Key words: apexification; apical barrier; Bioaggregate; mineral trioxide aggregate Correspondence to: Betul Memis Ozgul, Department of Pediatric Dentistry, Faculty of Dentistry, Ankara University, Besevler, Ankara, Turkey Tel.: 905363156948 e-mail: [email protected] Accepted 24 September, 2014
Abstract – Aim: The aim of this study was to compare the resistance to leakage of different thicknesses of Bioaggregate (BA) and 4-mm-thick white mineral trioxide aggregate (WMTA) in an apexification model using liquid filtration. Methods: 32 extracted mandibular premolar teeth were sectioned at the cemento-enamel junction and 3–4 mm from the tooth apex to obtain 12-mm-long root segments. The apical and coronal thirds were prepared with size two through six Gates Glidden burs. The teeth were divided into four groups according to material and thickness, as follows: Group 1: 2-mm BA; Group 2: 4-mm BA; Group 3: 12-mm (total length) BA; Group 4: 4-mm WMTA (control). The empty parts of the roots in Groups 1, 2, and 4 were filled with gutta-percha and root canal sealer, and leakage was measured using fluid filtration. The data were analyzed using the Kruskal–Wallis H-test. Results: No statistical differences in microleakage were observed between Groups 1, 2, and 4 (P > 0.05). Group 3 (roots filled completely with BA) showed significantly less leakage than the other groups tested (P < 0.01). Conclusions: The findings of this study showed that 12 mm of BA exhibited the best resistance to leakage. At the same time, 2–4 mm of BA showed similar results when compared to 4-mm MTA. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used as an apical barrier for apexification.
Immature permanent incisors with open apices may develop pulp necrosis usually as a result of trauma. Endodontic treatment of a non-vital tooth with an immature apex poses a particular challenge for the clinician. Although pulp regeneration treatment is growing in popularity, several studies have reported regenerative endodontic treatment of necrotic immature teeth to result in less-than-ideal outcomes (1–3). Nosrat et al. (4) reported a possible relationship between duration of pulp necrosis and treatment outcome, suggesting that long-standing infection might destroy cells capable of pulp regeneration. When regenerative treatment has failed or not considered as an option, apical barrier techniques are still used quite often in the treatment of such teeth (5, 6). The procedure entails closing the open apex with a biological material that acts as an apical barrier to permit immediate filling of the root canal (7). An ideal root-end filling material should be biocompatible, resist leakage, be antibacterial, have tissue-regeneration capacity, and should be easy to prepare and handle (8). Mineral trioxide aggregate (MTA) has good sealing ability and has demonstrated good success in one-visit apexification (9–12). Numerous studies have shown an apical plug of 3–5 mm to be sufficient for apical barrier techniques (13–16). However, MTA also has a number of disadvantages, such as crown discoloration (17, 18), 250
extended setting time (19–21), high costs (22), and difficulties in manipulation (23, 24). In addition, the findings on MTA’s biocompatibility are controversial, ranging from very good (24–26) to less favorable compared to other materials related to a discharge of cytotoxic ingredients such as aluminum and bismuth (27–29). Given these drawbacks, the search for an ideal root-end filling material is ongoing. Bioaggregate [(BioAggregate, Verio Dental Co. Ltd., Vancouver, Canada) (BA)] is a new material that has recently been introduced to the market as an alternative to MTA for use in perforation repair and vital pulp therapy and as a root-end filling material (30–32). BA has shown antibacterial effects (33) and sealing ability (34) comparable to that of MTA, and the absence of aluminum and bismuth in BA has resulted in a reported biocompatibility greater than that of MTA (29, 32, 35). Despite these positive characteristics, BA has not been sufficiently evaluated for its effectiveness in apical barrier techniques (36). Therefore, this in vitro study aimed to compare the microleakage using liquid filtration of different thicknesses of BA used as apical rootend fillings for apexification and to compare those with 4-mm MTA apical plugs that are commonly used in dental practice. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Resistance to leakage of apical plugs of BA Materials and method Specimen preparation
The study was conducted using 32 single-rooted human mandibular premolar teeth with mature apices and with no root caries, root fracture, or resorption that were extracted for orthodontic/periodontal reasons. The crowns were sectioned at the cemento-enamel junction (CEJ) using a diamond disk, and the apical portions were then sectioned to obtain standardized roots, 12 mm in length. Intracanal tissues were extirpated using a barbed broach (Medin Barbed Broach, Vlachovicka, Cezch Republic). To ensure a standardized blunderbuss shaping of the specimens the apical and coronal thirds (4 mm) were enlarged with Gates Glidden burs (GG, Antaeos, VDW GmbH, Munich, Germany) number 2–6 with a low-speed handpiece, the preparations were considered completed when a size 6 GG bur moved through the preparation without pressure. Following the preparations of apical and coronal thirds (4 mm), the middle thirds were instrumented using K-Flexofiles (G-star Medical Co., Ltd, Guangdong, China) up to a master file size of 80. The canals were irrigated between instruments with 2 ml of 5% sodium hypochlorite (NaOCl) and after instrumentation with 5 ml of 5% NaOCl, 5 ml of distilled water, 5 ml of 17% ethylenediaminetetraacetic acid (EDTA, Pulpdent Corporation, USA), and 5 ml of distilled water as a final rinse. The irrigation procedures were performed using a 27gauge needle; for each irrigation solution, a separate dental injector needle was used. The needle was placed in the coronal part of the teeth, and gentle pressure was applied during the irrigations. The canals were dried with paper points. Even though the same preparation procedures were followed for all teeth, radiographs were used to ensure that the canal walls had a conical blunderbuss shape that showed apical and coronal parts of the teeth were flared from the middle part mimicking the shape of young permanent teeth. The teeth were pressed into moisturized floral foam (Oasis Floral Foam, Kent, OH, USA) to simulate oral conditions and mimic the adaptation of periapical tissue during obturation. The teeth were then randomly divided into four groups, as follows: Group 1. (2 mm BA) (n = 8): The apical 2 mm were filled using Bioaggregate (Verio Dental Co. Ltd., Vancouver, Canada) mixed according to the manufacturers’ recommendations. The material was placed in the canals using the MTA Gun System (Dentsply, Maillefer, Switzerland) and then compacted using endodontic pluggers that were marked to the desired level of fill. Periapical radiographs of specimens were taken to control the level of fill. Group 2 (4 mm BA) (n = 8): The apical 4 mm were filled using BA as described above. Periapical radiographs of specimens were taken to control the level of fill. Group 3 (12 mm BA) (n = 8): The entire canal length (12 mm) was filled using BA as described © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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above. Periapical radiographs of specimens were taken to control the level of fill. Group 4 (4 mm MTA)(control group) (n = 8): The apical 4 mm were filled using white MTA (ProRoot MTA, Dentsply, Maillefer, Switzerland) mixed according to the manufacturers’ recommendations. Material was placed in the canals using the MTA Gun System (Dentsply, Maillefer, Switzerland) and then compacted using endodontic pluggers that were marked to the desired level of fill. Periapical radiographs of specimens were taken to ensure the level of fill. The length of the teeth from the radiograph was measured and proportioned by the real length (12 mm standard for each specimen), and the level of the fill was measured using the same proportion. To allow root-end filling materials to set completely, root segments were wrapped in wet gauze and placed in an incubator at 37°C for 96 h at 100% humidity. The setting of the material was gently checked by introducing a size 80 gutta-percha cone into the canal and tapping it with finger pressure. When the proper hardness was confirmed, cold lateral compaction technique was used with gutta-percha points to fill the unfilled root segments of specimens in Groups 1, 2 and 4. An ISO size 80 master cone (DiaDent, Almere, Netherlands) coated with AH-Plus Sealer (Dentsply, Maillefer, Switzerland) was inserted into the canal and lateral compaction with size 20 and 25 gutta-percha points was performed using finger spreaders size 30,25, and 20 (Dentsply, Maillefer, Switzerland). The compaction process was performed until the spreader sized 20 no longer penetrated to the coronal third of the canal (37). Periapical radiographs of specimens were again taken to ensure a complete fill. Root segments were again wrapped in wet gauze, placed in an incubator at 37°C for 24 h to allow complete set of the filling materials. Evaluation of leakage
Microleakage was evaluated using a modified version (38, 39) of the fluid transport method originally developed by Pashley et al. (40). The root specimens were attached to a hydraulic plastic tube and the connections of the specimen and tube were coated with epoxy resin (Pattex; Henkel, D€ usseldorf, Germany). The parts of the filtration model (tubes, micropipette, buffer, and etc.) were all filled with deionized water. To pass in a tiny air bubble, a microsyringe was inserted in the micropipette, and water was drawn back. The air bubble and the system were stabilized to locate the bubble in a suitable position within the micropipette. Regulated air from a pressure tank at 1240 cm H2O was applied from the apical aspects of the specimens, forcing water through any voids along the filler–canal interface. The linear displacement of the air bubble within the tube was measured over 10 min and converted to volume displacement expressed as ll 9 min 1 9 cmH2O 1. Fluid transport results were analyzed with SPSS statistical software (Version 11.5; SPSS Inc, Chicago, IL, USA) using the Kruskal–Wallis H-test.
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€ ul et al. Memisß Ozg€ This study found complete root filling with BA (12 mm) to provide statistically superior sealing when compared to 2- and 4-mm BA and 4-mm WMTA apical plugs. The results also showed 2-mm and 4mm BA and 4-mm WMTA to possess similar sealing properties. After initially producing a mechanical seal, MTA continues to dissolve, resulting in the formation of hydroxyapatite crystals that react with dentin to create a chemical adhesion (49). The fact that BA contains hydroxyapatite may explain the similarities in leakage results between BA and WMTA observed in the present study. Leal et al. (34) used glucose leakage to evaluate the sealing ability of WMTA and BA and, in line with our results, found no statistically significant difference between WMTA and BA. An in vitro study by Martin et al. (13) found the mean fluid conductance of 3- to 5-mm WMTA orthograde apical plugs to be 4 9 10 1 ll 9 min 1 9 cmH2O 1, which is higher than that of the 4-mm WMTA and 2mm and 4-mm BA groups in the present study (mean 1 9 10 2 ll 9 min 1 9 cmH2O 1). The difference may be explained by the fact that Martin et al. obturated the root canal space beyond the MTA apical plug with gutta-percha, but without a sealer, whereas in the present study, the roots were obturated with gutta-percha followed by a sealer. Tuna et al. (36) investigated the fracture resistance of immature teeth filled with BA and ProRoot MTA and found superior fracture resistance when BA was used for root filling. Considering that BA has shown biocompatibility superior to that of MTA (29, 32, 35) and good biomineralization (50) in addition to the sealing ability found in the present study, BA may be considered a promising material for use in trauma-induced endodontic treatment of teeth with immature apices;
Results
Fluid conductance values (mean standard deviation) are shown in Fig. 1. Specimens completely filled with BA showed the least amount of leakage (P < 0.01); however, there was no statistically significant difference between microleakage among any of the other groups (P > 0.05) (Table 1). Discussion
Filling materials developed for use in endodontics require good sealability to reduce bacterial leakage. Several studies have shown MTA to possess good sealability (41–45), but no study could be found that compared BA to WMTA in this regard. Studies on the use of MTA as apical plugs showed that MTA in thickness levels of 3–5 mm to be sufficient for apexification techniques (13–16). Valois and Costa (42) stated a 4 mm of MTA as a root-end filling was significantly more effective than lesser amounts in preventing dye leakage. Considering that, in this study, 4-mm WMTA apical plugs were used as control to compare with different thickness levels of BA. To mimic clinical conditions, this study used an apical barrier model, with roots shaped to a blunderbuss and the space above the apical plug obturated with gutta-percha and a root canal sealer. The fluid transport model developed by Pashley et al. (40) has been reported to provide a non-destructive method of quantitatively measuring microleakage around coronal restorations and endodontic retrograde fillings (46). This study used a modified version (38, 39) that has been reported to be more sensitive than bacterial penetration and conventional dye penetration methods used to measure microleakage (47, 48).
Fig. 1. Fluid conductance values of the BA Groups and WMTA Group.
Table 1. Statistical values of apical plugs used in the study Leakage
BA 2 mm BA 4 mm BA 12 mm MTA 4 mm
Kruskal–Wallis H
n
Mean
Median
Min
Max
Standard deviation
8 8 8 8
0.00988 0.01025 0.00050 0.00963
0.01000 0.01100 0.00000 0.00950
0.00800 0.00800 0.00000 0.00800
0.01200 0.01200 0.00200 0.01200
0.00146 0.00149 0.00093 0.00160
H
P
18.474
0.000
© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Resistance to leakage of apical plugs of BA however, long-term prospective clinical trials of this material are needed. Conclusion
The findings of this study showed that BA exhibited better results when used as 12-mm plugs compared to 2- to 4-mm plugs, which showed similar results when compared to 4-mm MTA that is used routinely in dental practice. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used for apical barrier techniques. Acknowledgement
The authors would like to thank Prof. Dr. Zafer C ß ehreli for his contribution to this study. Disclosures
We affirm that we have no financial affiliation (e.g., Employment, direct payment, stock holdings, retainers, consultantships, patent licensing arrangements, or honoraria), or involvement with any commercial organization with direct financial interest in the subject or materials discussed in this manuscript, nor have any such arrangements existed in the past 3 years. References 1. Petrino JA, Boda KK, Shambarger S, Bowles WR, McClanahan SB. Challenges in regenerative endodontics: a case series. J Endod 2010;36:536–41. 2. 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. 3. 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. 4. 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. 5. Damle SG, Bhattal H, Loomba A. Apexification of anterior teeth: a comparative evaluation of mineral trioxide aggregate and calcium hydroxide paste. J Clin Pediatr Dent 2012;36:263–8. 6. Jeeruphan T, Jantarat J, Yanpiset K, Suwannapan L, Khewsawai P, Hargreaves KM. Mahidol study 1: comparison of radiographic and survival outcomes of immature teeth treated with either regenerative endodontic or apexification methods: a retrospective study. J Endod 2012;38:1330–6. 7. Rafter M. Apexification: a review. Dent Traumatol 2005;21:1–8. 8. Gartner AH, Dorn SO. Advances in endodontic surgery. Dent Clin North Am 1992;36:357–78. 9. Torabinejad M, Pitt Ford TR, McKendry DJ, Abedi HR, Miller DA, Kariyawasam SP. Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys. J Endod 1997;23:225–8. 10. Shabahang S, Torabinejad M. Treatment of teeth with open apices using mineral trioxide aggregate. Pract Periodontics Aesthet Dent 2000;12:315–20.
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