Affiliations
doi: 10.29271/jcpsppg.2025.01.38ABSTRACT
Objective: To evaluate and compare the microleakage of mineral trioxide aggregate (MTA), Biodentine, and intermediate restorative material (IRM) when used as retrograde filling materials at depths of 1 mm, 2 mm, and 3 mm, utilising a dye penetration technique observed under a stereomicroscope.
Study Design: An in vitro experimental study.
Place and Duration of the Study: Department of Operative Dentistry and Endodontics, Ziauddin University, Karachi, Pakistan, from March to December 2024.
Methodology: A total of 120 extracted single-rooted teeth were randomly allocated into four groups: A (MTA), B (Biodentine), C (IRM), and D (positive control). Standardised retrograde cavities were created at three depths of 1 mm, 2 mm, and 3 mm and filled accordingly. Specimens were then placed in methylene blue dye for 72 hours, longitudinally sectioned, and examined under a stereomicroscope to measure dye penetration in millimetres. Data were analysed using the Kruskal-Wallis and One-way ANOVA tests, with statistical significance set at p ≤0.05.
Results: MTA exhibited the least dye penetration, followed by Biodentine, while IRM showed the greatest microleakage among the three materials. All materials demonstrated improved sealing with increased cavity depth, with 3 mm showing the lowest leakage overall.
Conclusion: MTA exhibited superior sealing ability among all materials, making it a material of choice for retrograde filling of roots. Biodentine is a viable alternative due to its fast setting time and ease of handling. IRM showed the highest microleakage, limiting its effectiveness to be used as a retrograde filling material.
Key Words: Microleakage, Retrograde filling, Mineral trioxide aggregate, Biodentine, Intermediate restorative material, Endodontic surgery.
INTRODUCTION
Effective endodontic therapy relies heavily on eliminating microbial contamination within the root canal and ensuring a hermetic seal to prevent reinfection.1 Despite improvement in endodontic techniques, periapical pathosis is not always resolved.2 Several complicating factors, such as severe canal curvatures, root fractures, open apices, failed apexification, resorptive defects, and procedural errors such as instrument separation, perforations, and overfilling, may hinder successful nonsurgical treatment. In such cases, surgical endodontic intervention becomes essential to preserve the tooth.3
The success of periapical surgery is closely linked to the proper preparation of a retrograde cavity, which allows an optimal seal in three dimensions to prevent microleakage.4
Various materials are available, such as amalgam, intermediate restorative material (IRM), super ethoxy benzoic acid (EBA), glass ionomer cement (GIC), composite, mineral trioxide aggregate (MTA), and Biodentine.5
Properties of a perfect root-end filling material include long-term 3-dimensional seal, good adaptation to the walls of the preparation, non-irritating, non-toxic, non-carcinogenic, biocompatible, radio-opaque, and easy to manipulate.6
MTA is biocompatible, antimicrobial, provides good sealing, sets well in a humid environment, elicits a positive tissue response, and promotes cementogenesis and dentinogenesis.7 However, it has a few drawbacks, such as difficult handling, long setting time, discolouration potential, and high cost.8
Biodentine shares many of MTA’s benefits, including biocompatibility, sealing ability, and promotion of hard tissue regeneration. It is considered more user-friendly due to its improved consistency and shorter setting time of approximately 12-13 minutes.9
IRM, a reinforced zinc oxide eugenol-based cement, exhibits reduced toxicity over time and causes minimal long-term inflammation. However, it poses challenges such as inconsistent setting behaviour influenced by environmental conditions and handling difficulties.10
Several studies have been carried out to check the sealing ability of retrograde filling materials at 3 mm preparation depths. However, little information is present regarding the performance of Biodentine, MTA, and IRM at different retrograde preparation depths, such as at 1 mm and 2 mm. Only two studies have been carried out internationally to check the sealing ability of these materials at different depths.11,12 No local studies have been carried out to check the sealing ability of these materials at different preparation depths.
The objective of this study was to compare the sealing ability of MTA, Biodentine, and IRM at three different depths—1 mm, 2 mm, and 3 mm—using the dye penetration method under a stereomicroscope.
METHODOLOGY
This in vitro experimental study was conducted at the Department of Operative Dentistry and Endodontics, Ziauddin University, Karachi, Pakistan, from March to December 2024.
The pass calculator was used to calculate the sample size according to the reference of the studies.11,12 The confidence level was taken as 95% and the power of the study as 80%. The calculated sample size was found to be eight each for the four groups.
Since the calculated sample size was too small, a sample of 120 subjects was included, i.e. 30 subjects per group. Each group was subdivided into 3 subgroups for different depths, i.e. 1 mm, 2 mm, and 3 mm. Each subgroup consisted of 10 samples.
Teeths that were single-rooted, caries-free, extracted due to periodontal or orthodontic reasons, and with fully develop root aspices and a sing canal (maxillary incisors and premolars) were selected. Teeth with previous root canal treatments, restorations, caries, fractures, and resorption were excluded.
Data collection was carried out by collecting 120 non-carious, extracted, single-rooted maxillary incisors, and premolars with a single canal from the Department of Oral and Maxillofacial Surgery at the studied centre. All extracted teeth were disinfected prior to use in the study. Ideal access cavities were prepared. Working length was established by inserting a #10 K-file until its tip appeared at the apical foramen, then subtracting 0.5 mm from that measurement. Root canals were prepared manually using the step-back technique up to a #45 master apical file. Irrigation was performed with 3% sodium hypochlorite and 17% EDTA solutions, followed by a final rinse with sodium hypochlorite (3%). The canals were obturated using gutta-percha with a calcium hydroxide-based sealer via the lateral condensation technique. GIC was used to seal the access cavities. All samples were stored at 37°C and 100% relative humidity for 7 days in an incubator. Teeth were decoronated at the cemento-enamel junction using a diamond bur. The apical 3 mm of roots were resected at the apical end at 90° to the long axis and divided into four groups. A Vernier caliper was used to measure the length of the bur before cavity preparation at different depths.
All groups (A, B, C, and D) were divided into 3 subgroups based on the depth of preparation (1 mm, 2 mm, and 3 mm). Each subgroup contained 10 teeth resulting in the following subgroups: A1, A2, A3, B1, B2, B3, C1, C2, C3, D1, D2, and D3. Retrograde cavities were prepared to depth of 1 mm, 2 mm, and 3 mm in subgroups A1, B1, C1, D1, A2, B2, C2, D2, A3, B3, C3, and D3, respectively. All cavities were prepared to 0.8 mm wide using a straight fissure bur. Following preparation, the cavities were irrigated with 17% EDTA, flushed with saline, and dried. Group A cavities were filled with MTA, Group B with Biodentine, Group C with IRM, and Group D, which was the positive control group, was not filled.
To isolate the region of interest, the external surfaces of root were coated with three layers of nail varnish, leaving the apical surface exposed and allowed to dry. Specimens were then submerged in 1% methylene blue dye for 72 hours. After staining, the samples were rinsed with running water for 15 minutes and then allowed to dry. The nail varnish was removed, and each tooth was longitudinally sectioned using a diamond disc under water cooling. The extent of dye penetration was measured using a stereomicroscope, and the deepest point of penetration was recorded in millimetres to assess micro-leakage (Figure 1).
The SPSS version 27.0 was used to analyse the results. The Shapiro-Wilk test was used to assess the normality of data. Numeric data, i.e. microleakage at different depths of 1 mm, 2 mm, and 3 mm, were expressed as median [IQR] / mean ± standard deviation for MTA, Biodentine, IRM, and control groups. Kruskal-Wallis test was used to evaluate microleakage for different materials (MTA, Biodentine, and IRM) and at the different depths (1 mm, 2 mm, and 3 mm), followed by Post-Hoc analysis using the Mann-Whitney U test.
Figure 1: Microleakage at 3 mm filled with (A) MTA, (B) Biodentine, (C) IRM, and (D) Positive control group.
Figure 2: Comparison of the microleakage between the groups at (A) 1 mm depth, (B) 2 mm, and (C) 3 mm depth.
One-way ANOVA test, followed by the Post-hoc Tuckey’s test, was used to compare the microleakage at different depths for control group (1 mm, 2 mm, and 3 mm) and assess the microleakage. A p-value ≤0.05 was considered statistically significant. Since this was an in vitro study, there were no effect modifiers.
RESULTS
Table I shows the extent of microleakage across the experimental and control groups at each cavity depth.
Figure 3: Comparison of microleakage between different materials. (A) MTA, (B) Biodentine.
At 1 mm, MTA and Biodentine showed significantly lower leakage than the control group (p <0.001 and 0.008). IRM was not significantly different from the control group, indicating less effectiveness (Figure 2A). At 2 mm, MTA and Biodentine both had significantly lower leakage than the control group (p = 0.001 and 0.004). IRM showed higher leakage than the MTA and Biodentine, confirming its lower sealing ability (Figure 2B). At 3 mm, MTA showed significantly lower leakage than the control (p <0.001) and IRM groups (p = 0.006). Biodentine also outperformed the control group (p <0.001), but was not significantly different from the MTA group (p >0.99). IRM did not differ significantly from the control group (p = 0.398, Figure 2C).
For the control group, no statistically significant result was observed between different depths, as the p-value was 0.240.
There was a significant difference in microleakage between MTA, Biodentine from IRM, and the control groups (Table II).
Table I: Comparison of microleakage among material groups at different depths of cavity preparation.
|
Depth of cavities |
Groups |
Microleakage (in mm) Median [IQR] |
p-values |
|
1 mm |
MTA Biodentine IRM Control |
2.14 [0.96] 3.05 [1.66] 3.40 [1.38] 4.14 [0.88] |
<0.001* |
|
2 mm |
MTA Biodentine IRM Control |
2.40 [1.23] 2.26 [0.91] 2.85 [1.19] 4.97 [1.81] |
<0.001* |
|
3 mm |
MTA Biodentine IRM Control |
1.14 [1.08] 1.86 [0.81] 2.76 [0.63] 5.02 [1.19] |
<0.001* |
|
*Kruskal-Wallis test was applied. |
|||
Table II: Comparison of the microleakage at different depths for each material.
|
Groups |
Depths |
Microleakage, median [IQR] / standard deviation |
p-values |
|
MTA |
1 mm 2 mm 3 mm |
2.14 [0.96] 2.40 [1.23] 1.14 [1.08] |
<0.001* |
|
Biodentine |
1 mm 2 mm 3 mm |
3.05 [1.66] 2.26 [0.91] 1.86 [0.81] |
0.005* |
|
IRM |
1 mm 2 mm 3 mm |
3.40 [1.38] 2.85 [1.19] 2.76 [0.63] |
0.240* |
|
Control |
1 mm 2 mm 3 mm |
4.21 ± 0.65 4.88 ± 1.55 4.95 ± 0.66 |
0.240# |
|
*Kruskal-Wallis test was applied, #One-way ANOVA test was used. |
|||
MTA and Biodentine showed lower microleakage than the control group. IRM showed less microleakage than the control group; however, the difference was not statistically significant. IRM showed higher microleakage than MTA and Biodentine. Moreover, no significant difference was observed between MTA and Biodentine, indicating that both materials have comparable sealing ability. Sealing ability improved as the depth of retrograde preparation increased. MTA exhibited the least microleakage at the depth of 3 mm (p = 0.001, Figure 3A).
Biodentine showed a significant reduction in microleakage with increasing depth, with the least leakage observed at 3 mm (Figure 3B). IRM exhibited the highest microleakage across all depths. Although leakage decreased with increase in depth, the differences were not statistically significant.
DISCUSSION
Achieving a reliable apical seal is crucial for the success of surgical endodontic procedures.13 This study was designed to assess the sealing performance of three root-end filling materials, such as MTA, Biodentine, and IRM, at varying retrograde cavity depths. To minimise apical microleakage, root resections were performed at a 90-degree angle to the tooth's long axis. This orientation reduces the number of open dentinal tubules at the apex, thereby improving sealing potential.14 The results of this study indicated that MTA exhibited the least microleakage, followed by Biodentine, while IRM showed the highest microleakage. These findings are similar to previous studies that have assessed the sealing ability of these materials under similar conditions.11,12
This study found that MTA exhibited the best sealing ability, particularly at a depth of 3 mm. This finding is consistent with prior research by Torabinejad et al., which recognised MTA’s ability to provide a tight seal and induce a favourable biological response. Its composition, containing calcium and phosphate ions similar to those in natural tooth structure, contributes to the formation of a hard tissue barrier and helps to isolate the filling from surrounding tissues. MTA's capacity to set in a moist environment also contributes to its superior sealing behaviour.15 Similarly, Falkowska et al. found that MTA’s resistance to washout and superior marginal adaptation make it a preferred material for retrograde fillings.16 A study by Toia et al., using micro-CT analysis, also confirmed that MTA exhibited significantly lower microleakage than other materials at depths greater than 3 mm. However, they noted that MTA’s handling properties and extended setting time have limitations.17 These findings are consistent with the present study, in which MTA showed the least microleakage but posed challenges in terms of manipulation.
In this study, Biodentine, which performed comparably to MTA at deeper depths, exhibited slightly more microleakage at shallower depths. Similarly, a study by Eid et al. reported no significant difference in microleakage between Biodentine and MTA.18 This study showed that Biodentine showed significantly lower microleakage than IRM but was slightly less effective than MTA. This could be due to the greater washout property of Biodentine when placed in a simulated blood solution, as tested in a study.16 Another study by Nabeel et al. highlighted that Biodentine’s favourable biocompatibility in the initial stages of healing and comparable biomineralisation make it a viable alternative as root-end filling material.19 This matches the findings of the present study, suggesting that while MTA remains the gold standard, Biodentine can be considered as an acceptable alternative in periradicular surgeries.
This study found that IRM exhibited the highest microleakage among the three materials and did not significantly differ from the control group in preventing microleakage. This finding is consistent with another study that showed significantly higher microleakage ability of IRM than MTA, Portland cement, and light cure GIC in retrograde fillings, as the placement of IRM requires careful planning of the dentine surface and application in a dry field.20 Another reason for IRM’s poor sealing ability is that, following endodontic surgery, fibroblasts and cells do not attach well to its surface. This may be due to eugenol leached from the materials into the dentinal tubules.21
The present study showed that the sealing ability of all materials improved with increasing retrograde preparation depth, with the lowest microleakage observed at 3 mm. Increased depth provides the stability and efficacy of the seal, with a large surface area for adherence and occlusion of apical tubules, which are available for the passage of fluid into root-ends.22 However, a study stated that the depth of preparation did not influence the sealing ability of materials.12 The retrograde preparation greater than 3 mm is not advisable due to the increase in technical difficulties, the use of longer tips, and the formation of dentinal cracks.12 Preparation depth less than 3 mm can lead to more leakage because of gaps and voids in shallow root-end filling, promoting bacterial ingress in periapical tissues.23 So, the 3 mm retrograde preparation is considered as the gold standard.
This study suggests that MTA is the material of choice for retrograde fillings. Biodentine can also serve as a promising alternative due to its ease of handling and rapid setting time. Whereas, IRM may not provide adequate long-term sealing ability, particularly at shallow depths.
This study was conducted in vitro, so results may not replicate the environmental conditions of the oral cavity. There could be possible variability in dye penetration and potential overestimation of leakage compared to other more advanced methods such as fluid filtration.
Future research should focus on in vivo studies to assess the sealing ability at varying depths using novel materials that include the superior properties of both MTA and Biodentine. Additionally, studies with advanced imaging techniques, such as cone beam computed tomography (CBCT), can better assess marginal adaptation and microleakage.
CONCLUSION
This study provides valuable insights into the sealing efficacy of different retrograde filling materials at varying depths. MTA demonstrated the best sealing ability, with Biodentine performing comparably at greater depths, followed by IRM, which showed the highest microleakage. The better sealing ability was achieved at 3 mm for all the materials. This shows the importance of selecting materials placed at proper depths with optimal sealing ability for the success of periapical surgeries.
ETHICAL APPROVAL:
The study was performed after receiving ethical approval from the Institutional Review Board of Ziauddin University, Karachi, Pakistan (Reference code: 6860323MSOM).
PATIENTS’ CONSENT:
No informed consent was obtained as the study was conducted on already extracted teeth.
COMPETING INTEREST:
The authors declared no conflict of interest.
AUTHORS’ CONTRIBUTION:
MSG: Conception, study design, data acquisition, analysis, and manuscript drafting.
HA: Conception, study design, manuscript revision.
Both authors approved the final version of the manuscript to be published.
REFERENCES