|Year : 2015 | Volume
| Issue : 3 | Page : 145-149
A comparative evaluation of ideal apical sealing material for open apex single rooted permanent tooth: An in vitro study
Chiranjit Ghosh1, Gautam Kumar Kundu2, Shabnam Zahir2, Subrata Sarkar2, Badruddin Ahmed Bazmi2, Sudipta Kar2
1 Department of Pedodontics and Preventive Dentistry, Haldia Institute of Dental Science and Research, Haldia, West Bengal, India
2 Guru Nanak institute of Dental Science and Research, Kolkata, West Bengal, India
|Date of Web Publication||4-Aug-2015|
57, Manindra Gopal Mitra Sarani, Bidya Lanka, Nandi Bagan, Chandan Nagar, Hooghly - 712 136, West Bengal
Introduction: Traumatic injury and dental caries in developing tooth can cause irreversible damage to the pulpal tissue, which hinders the normal physiologic root development. Aims and Objectives: The aim was to find out the sealing efficacy of mineral trioxide aggregate (MTA) as an ideal apexification material of a permanent tooth with an open apex by comparative evaluation of grey and white MTA of different thickness and time interval in vitro. Materials and Methods: A total of 144 teeth were randomly distributed into 6 equal test groups containing 24 teeth each and then filled with white and gray MTA to thickness of 1, 2, and 4 mm. Microleakage of these samples was studied by bacterial leakage model at definite intervals (After 24 h,7 th day,15 th day, and 30 th day). Results: After 24 h, for 1 mm thickness, grey MTA showed less leakage than white MTA, but the difference is not statistically significant at 5% level (Z = 0.32, P = 0.75). After 7 days, in 1 and 2 mm thickness, White MTA showed 64.71% and 16.67% leakage, while Grey MTA revealed 50% and 8.33% leakage in the same category. No leakage was found among the samples of 4 mm in both MTA. After 15 days in 1 mm, 100% leakage was recorded in both MTA. In 2 mm, presence of leakage is 15% for White and 13.64% leakage were present in Grey MTA. However, this difference is not significant (Z = 0.126, P = 0.9). In 4 mm MTA, only 1 leakage was found in White and none for Grey. This difference is not significant (Z = 1.02, P = 0.31). After 30 days, in 2 mm, 9% more leakage was observed in White MTA samples (23.53%) than that of Grey MTA (14.29%). In the category of 4 mm, 0.37% more leakage was observed in White MTA samples (8.70%) than that of Grey MTA (8.33%). However, this difference was not statistically significant. Conclusion: The present study showed that apical barrier of 4 mm demonstrated less leakage than 1 and 2 mm barrier in both White and grey MTA after 30 days of study and grey MTA demonstrated significantly less leakage than white MTA.
Keywords: Grey mineral trioxide aggregate, trauma, white mineral trioxide aggregate
|How to cite this article:|
Ghosh C, Kundu GK, Zahir S, Sarkar S, Bazmi BA, Kar S. A comparative evaluation of ideal apical sealing material for open apex single rooted permanent tooth: An in vitro study. SRM J Res Dent Sci 2015;6:145-9
|How to cite this URL:|
Ghosh C, Kundu GK, Zahir S, Sarkar S, Bazmi BA, Kar S. A comparative evaluation of ideal apical sealing material for open apex single rooted permanent tooth: An in vitro study. SRM J Res Dent Sci [serial online] 2015 [cited 2019 Dec 5];6:145-9. Available from: http://www.srmjrds.in/text.asp?2015/6/3/145/162149
| Introduction|| |
Traumatic injury and dental caries in developing tooth can cause irreversible damage to the pulpal tissue, which hinders the normal physiologic root development. Gassner et al. reported that 81.2% of all traumatic dental injuries occur before 30 years of age, of that almost 50% before 10 years of age.  Endodontic treatment of such immature tooth has many potential complications including endodontic and reparative aspects. Unfavorable crown root ratio due to short immature root complicates further post endodontic restoration. Thin root dentin and cementum hinders the biomechanical preparation and makes the tooth very susceptible to fracture. Without apical stop or constriction, it is difficult to limit the filling process to achieve a physical barrier at the root end. A variety of materials were used for this purpose. Since 1964 Ca(OH) 2 is in use for this condition, but multiple visits, fracture susceptibility, and microleakage are considered as major disadvantages for such material.
In 1995, Torabinejad , described mineral trioxide aggregate (MTA) as the best apical sealing material used for this purpose, which is a mixture of 75% Portland cement (composed of dicalcium silicate, tricalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite), 5% Gypsum (acts as a retarder), 20% bismuth oxide (provides radio-opacity).  It also contains traces of SiO 2 , CaO, MgO, K 2 SO 4, and Na 2 SO 4 . It is marketed in two forms, white and grey. The aim of the present study is to find out the sealing efficacy of MTA as an ideal apexification material of a permanent tooth with an open apex by comparative evaluation of grey and white MTA of different thickness and time interval in vitro.
| Materials and Methods|| |
A total of 148 single-rooted, caries-free, human maxillary teeth with straight canals were selected for this experiment. The teeth were stored in 10% neutral formalin, autoclaved and kept in 0.5% sodium hypochlorite (NaOCl) for no longer than 7 days. 146 teeth were prepared as follows: Standard access cavities were made with a straight fissure and round diamond bur and root canals were negotiated by inserting a size 15 K-file into the canal until its tip reaches the apical foramen. Under a continuous water or normal saline spray, crown of the teeth were excised at the level of cement-enamel junction at 90° to the long axis of the teeth with a carborundum disc in a high speed straight micro motor hand piece to facilitate their manipulation. The coronal and middle third of the canal was prepared using Gates Glidden drills (Dentsply Maillefer, Ballaigues, Switzerland) of sizes 2, 3. The apical foramen was enlarged with a number 140 file to standardize the diameter. The preparation was completed using a step back of 1-mm increments. The canals were irrigated with freshly prepared 5.25% NaOCl between each instrumentation. The apical 3 mm of the roots were then excised at 90 ° to the long axis of the teeth. To complete the preparation, a final flush with 5.25% NaOCl was performed and canals were dried with paper points (Dentsply Maillefer). Two layers of nail polish were applied to the external surfaces of all roots, in order to prevent bacterial leakage through lateral canals or other discontinuities in the cementum.
A total of 144 teeth were randomly distributed into 6 equal test groups containing 24 teeth each and then filled with white and gray MTA to thickness of 1, 2, and 4 mm. Two unfilled prepared teeth served as the positive controls. Another two unprepared teeth served as the negative controls. White and grey MTA was prepared according to manufacturer's direction and delivered to the canal space with amalgam carrier and condensed with the cotton covered tip of a size 40 K-file for achievement of the plug. We used a hand plugger with a rubber stop positioned 1, 2, and 4 mm shorter than the root canal length for final condensation. The excess material was removed from the canal space. Finally, the root canals were cleaned with the tip of an instrument wrapped in moist cotton.
Bacterial leakage test
The apparatus used in this study was modified from the previous study done by Imura et al. in 1997. , Coronal end of individual tooth was inserted in an autoclavable plastic tube in such a fashion, so that the major portion of the apical end remains out of the tube. The plastic tube was used to create the bacterial reservoir. The interface between the tooth and the plastic tube was sealed with cyanoacrylate adhesive. The system was placed in a 5 ml glass flask containing 3.5 ml of sterile brain heart infusion medium. Efficacy of cyanoacrylate seal was verified by sterile methylene blue dye. Only the leak proof specimens were accepted for the study. The interface between the plastic tube and the glass flask was sealed with cyanoacrylate adhesive. The whole apparatus was incubated at 37°C for 4 days to ensure sterilization. 3-5 well isolated Staphylococcus colonies of similar appearance is touched using a sterile loop and emulsified in 3-4 ml of sterile brain heart infusion broth and incubated at 37°C. In a good light, the turbidity of the suspension is matched to the turbidity standard equivalent to mcfarland 0.5. With the help of micropipette 0.8 ml of brain heart infusion turbid with bacteria was added to the upper plastic chamber of each experimental leakage model [Figure 1]. The contents of the upper chamber were replaced and fresh brain heart infusion turbid with bacteria was added twice per week along the duration of the experiment period. The glass flasks were placed in the incubator and observed for turbidity of the broth at an interval of 24 h, 7 th , 15 th , and 30 th day. Once turbidity was detected the sample was removed from the incubator and the data of the specific sample was recorded in the data sheet.
The results obtained have been analyzed using Z-test or Chi-square test.
| Results and Observations|| |
The specimens in the positive control group exhibit turbidity within first 24 h, whereas in the negative control group no evidence of turbidity was noted throughout the experiment.
After first 24 h of observation, for 1 mm thickness, grey MTA (6 samples) showed less leakage than that of White MTA (7 samples), but the difference is not statistically significant at 5% level (Z = 0.32, P = 0.75). No leakage was observed among the samples of 2 mm and 4 mm of thickness in both White and Grey MTA. This is statistically highly significant (P < 0.001 and P < 0.01, respectively, for white and grey MTA) [Table 1].
|Table 1: Leakage present by thickness of MTA (grey and white) after first 24 h|
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After 7 days, in case of 1 mm and 2 mm thickness, white MTA showed 64.71% (11 out of 17 samples), and 16.67% (4 out of 24 samples) leakage, while grey MTA revealed 50% (9 out of18) and 8.33% (2 out of 24) leakage in the same category. No leakage was found among the samples of 4 mm category in both white and grey MTA. In 1 and 2 mm leakage is higher in White compared to Grey, but the differences are not significant. However, the results of Chi-square analysis are significant, which indicates an inverse relation between increased thickness and leakage [Table 2].
|Table 2: Leakage present by thickness of MTA (grey and white) on 7th day|
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After 15 days in 1 mm thickness of MTA, 100% leakage was recorded in both white and grey. 1 out of 24 white MTA samples that belonged to 4 mm category showed leakage, but no leakage was observed among the samples of grey MTA in the same category. In 2 mm thickness of MTA, presence of leakage is 15% for White and 13.64% leakage were present in Grey. However, this difference is not significant (Z = 0.126, P = 0.9). In 4 mm MTA, only 1 leakage was found in White and none for Grey. This difference is also not significant (Z = 1.02, P = 0.31). Here also leakage has an inverse relation with thickness of MTA, which is highly significant (P < 0.001 and P < 0.001 for white and grey MTA, respectively) [Table 3].
|Table 3: Leakage present by thickness of MTA (grey and white) on 15th day|
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After 30 days, in the 2 mm category, 9% more leakage was observed in white MTA samples (23.53%) than that of grey MTA (14.29%). In the category of 4 mm, 0.37% more leakage was observed in white MTA samples (8.70%) than that of grey MTA (8.33%). However, this difference was not statistically significant [Table 4].
|Table 4: Leakage present by thickness of MTA (grey and white) on 30th day|
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In first 15 days of time period, incidence of leakage increases for white MTA and after that same samples showed a gradual decrease in the incidence of leakage. In the case of grey MTA, decrease in incidence of leakage was also seen in the last 15 days. The cause of such finding is not known, however it is assumed that with the course of time a large number of samples were excluded from 1 and 2 mm category due to leakage in the early part of the study. This available data mainly reflects the leakage of 4 mm thickness of the sample. As such Chi-square analysis does not reveal any significant overall increase. If we analyze the data for 1 and 7 days only for White MTA, we found it significant at 5% level. Again analyzing the data of grey MTA from 1 st to 15 th day (period over which leakage continued to increase) the result is not significant at 5% level, but significant at 10% level [Diagram 1].
| Discussion|| |
Many factors has been identified in the world literature to influence bacterial penetration of MTA, including the types of MTA, thickness of the MTA, length of the study time, type of bacteria, methods of insertion, and compaction and the leakage evaluation method. The present study was intended to evaluate the influence of the first three factors.
The present study revealed grey MTA as a better apexification material than white MTA. Matt et al.  observed similar results in their study. Coneglian et al.  found that gray MTA and Portland cement had better sealing ability than white MTA when used as apical plugs. Valois and Costa.  concluded that after 42 days grey MTA showed leakage in 9.1% of samples, white MTA leaked in 36.4% of samples, and all samples of vertically condensed Gutta-percha and Kerr pulp canal sealer EWT (Kerr Corp., Orange, CA, USA) leaked after 19 days. Asgary et al.  observed significant difference between gray and white MTA, in the contents of aluminum trioxide (Al 2 O 3 ), magnesium oxide (MgO), and iron oxide (FeO), but these differences are not enough to explain better efficacy of gray MTA to bacterial leakage. It is hypothesized that slight volumetric shrinkage occurred with the white product that accounts for the increased leakage. Bidar et al.  showed that the gap between gray MTA and the dentinal wall is less than white MTA and Portland cement, but there was no significant difference between the materials tested in this study (P < 0.05). Ferris and Baumgartner compared the sealing ability of gray and white MTA to seal furcation perforation by an anaerobic bacterial leakage model and found no significant difference between the two preparations.  Tselnik et al.  conducted that there was no statistically significant difference in leakage between in gray and white MTA or gray MTA and Fuji II at 30, 60, or 90 days. Zahed  conducted that there was no statistically significantly difference between gray MTA and white MTA or gray MTA and Gutta-percha and sealer (P < 0.05). Hamad et al.  said that no statistically significant difference in leakage was found between white and gray MTA. However, there was significantly more leakage when the perforation was challenged from the orthograde than the retrograde direction (P < 0.001).
The present study clearly showed that 4 mm thick plugs were more efficient than 2 mm, 1 mm plugs, regardless of the material utilized. Different studies using 1-10 mm thick apical plug suggested that best results can be achieved if the thickness is in between 3 mm and 5 mm. Our results are at par with the studies of Matt et al.  and Al-Kahtani et al., in which 5 mm thick apical plugs showed the best results. Torabinejad and Chivian also have advocated 3-4 mm thick MTA in endodontic surgical techniques with class I preparation. Hachmeister et al.  placed MTA as an apical barrier at a thickness of 1 mm or 4 mm, with and without prior calcium hydroxide medication, and demonstrated a statistically significant greater resistance to force with a 4 mm thickness of MTA, regardless of calcium hydroxide use. Valois and Costa  concluded that MTA produces an excellent seal when the thickness is at least 4 mm.
It is clear that with increasing time period presence of leakage increases. In this study for White MTA, however on 15 th and 30 th day this leakage began to decrease. For grey MTA the increase in leakage continued up to 15 th day then it decreased on 30 th day. Hachmeister et al.  said that teeth with or without calcium hydroxide pretreatment showed bacterial penetration during the first 10 days of the study. By day 70, all MTA barriers showed bacterial penetration. Lawley et al. said that Ultrasonic placement of MTA resulted in a significant reduction of bacterial penetration after 45 days. However, after 90 days no significant difference was observed between ultrasonic and nonultrasonic group. 
| Conclusion|| |
The present in vitro study showed the advantage of using grey MTA over White variety as an apexification material. Results also suggest that 4 mm thickness is always better than 1 mm and 2 mm irrespective of the material used. Review of literature supports the results of his study.
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[Table 1], [Table 2], [Table 3], [Table 4]