Comparison of sealing ability of Geristore and Mineral trioxide aggregate as root-end filling material in dry and saliva-contaminated environment

Abstract

Objective

To evaluate the sealing capabilities of mineral trioxide aggregate (MTA) and Geristore as retrograde filling materials in dry and saliva-contaminated environments.

Methodology

Seventy-two extracted single-rooted premolars were included. Root canals were prepared and obturated following decoronation. Each root’s apical 3 mm was removed, and via ultrasonic tips, uniform retrograde cavities were created. The teeth were divided into four groups (n = 18) at random: MTA dry, MTA wet, Geristore dry, and Geristore wet. After that, samples were submerged in methylene blue dye (1%) for 48 h. A stereomicroscope was used to examine the longitudinally sectioned roots at a magnification of 25.6×. The linear penetration of dye was measured using ImageJ software. Tukey’s post hoc test and one-way analysis of variance (ANOVA) were used in SPSS data analysis.

Results

One-way ANOVA demonstrated a significant difference in dye penetration among the four groups (p < 0.001). In both dry (0.64 ± 0.42 mm) and wet (0.65 ± 0.32 mm) conditions, Geristore demonstrated similar sealing ability (p = 1.000). In contrast, MTA exhibited significantly lower dye penetration in dry conditions (0.47 ± 0.21 mm) than in wet conditions (1.13 ± 0.26 mm; p < 0.001), with the wet MTA group demonstrating the greatest microleakage.

Conclusion

Geristore demonstrated consistent sealing ability irrespective of environmental conditions. Although MTA performed similarly in dry conditions, its sealing ability was significantly compromised by salivary contamination. Geristore may therefore be a more reliable root-end filling material when moisture control is difficult.

Introduction

Successful endodontic treatment relies heavily on thorough microbial elimination and achieving a hermetic seal of the root canal system [1]. The reported success rate of primary root canal therapy ranges from 94 to 97% [2–4]. However, failures can still occur, often due to factors such as persistent intra-radicular or extra-radicular infections, the presence of true cysts, or foreign body reactions [5].

While persistent intra-radicular infections may be managed through conventional non-surgical retreatment, surgical intervention becomes necessary when retreatment is not feasible or in cases involving extra-radicular pathology [4, 5]. Surgical endodontics typically involves apicoectomy, in which 3 mm of the apical root is resected, followed by ultrasonic root-end preparation and sealing with a biocompatible root-end filling material [6]. The primary goal of this procedure is to create a hermetic apical seal to prevent microbial leakage in the periapical area, thus promoting healing of the periapical tissues [1, 2]. Hence, the quality of the apical seal is critical in determining the success of surgical endodontics [1].

Over the years, diffrerent materials have been explored for filling the root end cavities, which includes amalgam, resin composites, glass ionomer cements (GICs), and more recently, bioactive cements. Of all the materials, mineral trioxide aggregate (MTA) is considered as the gold standard due to its superior properties such as excellent sealing ability, biocompatibility, ability to induce hard tissue formation, and effective performance in moist environments [7, 8]. However, MTA presents certain drawbacks, including extended setting time, challenging handling characteristics and potential for tooth discoloration [9]. These limitations have prompted research into alternative materials with improved clinical handling and comparable or superior sealing properties.

Geristore (DenMat, USA), is a dual-cure, polyacid-modified glass ionomer cement, and has shown promising results in dental applications such as subgingival restorations, repair of resorptive defects, and perforation management [10]. Its favorable properties include excellent biocompatibility, low solubility, high fluoride release, dentin bonding, dual-cure setting with minimal shrinkage, and enhanced radiopacity [10]. Studies carried out to analyze the influence of different retrograde filling materials on gingival fibroblast cells showed better cell attachment to Geristore compared to MTA [10–12].

Although Geristore has been available since the early 1990s, published evidence evaluating its use specifically as a root-end filling material remains comparatively limited, with much of the available literature comprising earlier laboratory investigations, whereas MTA has been investigated extensively in both experimental and clinical studies [11, 13, 14]. Moreover, the published literature has reported inconsistent findings regarding its sealing ability when compared with MTA, partly because of differences in contamination models, experimental conditions, and leakage assessment methods. For example, Pandey et al [1]. reported superior sealing ability of Geristore under saliva-contaminated conditions, whereas other studies have demonstrated favorable performance of MTA under different experimental settings [12, 13]. Since moisture contamination remains a common clinical challenge during endodontic microsurgery, further evaluation using a standardized saliva-contamination model is warranted. Therefore, the present study was designed to compare the sealing ability of MTA and Geristore under standardized dry and saliva-contaminated conditions using quantitative dye penetration analysis. The null hypothesis was that there would be no significant difference in the sealing ability of MTA and Geristore under either dry or saliva-contaminated conditions.

Methodology

This in-vitro experimental study was carried out at the dental department of Aga Khan University Hospital (AKUH), Karachi, from January to April 2025, following the exemption from Ethical Review Committee (ERC# 2022-8188-23292). Specimen selection was done consecutively as per the availability and inclusion criteria. The size of the samples was calculated using OpenEpi version 3.01 (open-source statistics for public health) to detect a mean difference in the sealing ability of 0.55 units between the two groups (Geristore: 1.19 ± 0.80; MTA: 1.74 ± 0.80). Keeping the power of 80%, significance level of 5% [11], and confidence interval at 95%, the size of the samples calculated was 17 teeth per group. After applying a 5% inflation to account for any processing error, the final sample comproised of 18 teeth per group. Since there were four groups in the study, a total of 72 teeth were needed to address the research question.

Sample selection

The study included previously extracted human single-rooted premolars, exhibiting a single canal, and with closed apices. Teeth were excluded if they exhibited root resorption, caries, or fractures, or if they had root canal curvatures exceeding 20°, as confirmed radiographically. Additionally, teeth that had undergone previous root canal treatment were excluded from the study.

Data collection procedure

After obtaining ERC exemption, extracted human single-rooted premolar teeth that fulfilled the inclusion criteria were retrieved from the tooth bank maintained at the dental clinics, AKUH (Fig. 1a). The teeth were cleaned with an ultrasonic scaler to remove debris. Disinfection was carried out by immersing the teeth in a 3% sodium hypochlorite solution, followed by storage in a solution of normal saline at room temperature until use.

Fig. 1.

Experimental workflow showing the methodology of sealing ability assessment across the study groups.

To standardize specimen length, all roots were sectioned to 15 mm from the apex using a high-speed diamond disc under water irrigation. A #10 K-file was inserted to establish working length. Root canals were cleaned and prepared using the Protaper Next rotary file system (Dentsply Maillefer, Ballaigues, Switzerland) with an endomotor, sequentially up to X3, as per the manufacturer’s instructions. After each file, canals were irrigated with 3% sodium hypochlorite and dried with paper points after completion of instrumentation. Obturation was performed using the warm vertical compaction technique with a calcium hydroxide-based sealer (Sealapex, Sybron Kerr, WA). The quality of obturation was verified radiographically, and access cavities were restored with light-cure composite resin (Dentsply Sirona, USA) (Fig. 1b). All teeth were stored in normal saline solution for 24 hours.

Subsequently, the apical 3 mm of the root ends were resected perpendicular (90°) to the long axis using a straight fissure bur (Mani Inc., Japan) with a high-speed handpiece under water cooling (Fig. 1c). Root-end cavities (3 mm in depth) were prepared using ultrasonic microsurgical tip E10D (Guilin Woodpecker Medical Instrument Co. Ltd.) powered by a piezoelectric device (MTS, Obtura Spartan Inc.) under constant irrigation (Fig. 1d). The cavity depth was confirmed using a WHO periodontal probe, followed by saline irrigation and drying with cotton pellets.

Specimen preparation and placement of both root-end filling materials were carried out by a single, calibrated operator (BF), who had prior training and hands-on experience with both MTA and Geristore, thereby minimizing operator-related variability in material handling and placement. Dye penetration was evaluated by a second examiner (FRK), who was blinded to group allocation.

The prepared root-end cavities were randomly allocated into four groups (n = 18 per group) using the lottery method. Allocation concealment was maintained using sequentially numbered, sealed opaque envelopes containing the group assignments, which were prepared in advance and opened by an independent operator immediately before material placement. The independent operator was not involved in specimen preparation, material placement, or outcome assessment. The groups were as follows (Fig. 1e, f):

• Geristore dry (n = 18): Geristore in dry environment

• Geristore wet (n = 18): Geristore in saliva-contaminated environment

• MTA dry (n = 18): MTA in dry environment

• MTA wet (n = 18): MTA in saliva-contaminated environment

Geristore (DenMat Holdings LLC, Lompoc, CA, USA) and Endo-Eze™ MTAFlow™ Repair Cement (Ultradent Products, Inc., South Jordan, UT, USA) were used as the retrograde filling materials. Both materials were manipulated and placed into the prepared root-end cavities according to the manufacturers’ instructions. In the saliva-contaminated groups, artificial saliva (Oralieve, Europharma Concepts Ltd) was dispensed into each root-end cavity using a micropipette before placement of the respective filling material. No contamination was introduced in the dry groups, before placement of the filling materials. Nail varnish (two layers) was coated to all the teeth, leaving the resected root-end surface exposed (Fig. 1g). The specimens were kept in 1% methylene blue dye for 48 h (Fig. 1h). After that, all the teeth were rinsed under tap water for 15 min and allowed to air-dry. All the specimens were then sectioned bucco-lingually, using a slow-speed diamond disc under constant water irrigation to prevent heat generation (Fig. 1j). The degree of linear dye penetration at the root-end filling interface was assessed using a stereomicroscope (AM-4000, ALLTION, Guangxi, China) at the magnification of 25.6X. High-resolution digital images of each sectioned specimen were recorded using a Canon camera (EOS 4000D), mounted on the microscope. These images were transferred into Fiji ImageJ software (Version 2.0) for analysis. The degree of linear dye penetration was considered a direct indicator of sealing ability, with less penetration of the dye corresponding to greater sealing ability of the material.

The ImajeJ software was calibrated against a standard scale before analysis, in order to ensure the accuracy of the measurement. A UNC-15 probe (markings spaced 1 mm apart) was kept alongside of each specimen and standardized images of the sectioned root samples were captured. In ImageJ, the scale was set by selecting the pixel length corresponding to one 1 mm segment on the probe and defining it as 1 mm within the software’s calibration settings. The linear extent of dye penetration was then measured from the apical end of the root-end filling material coronally at the interface between the material and the prepared cavity wall. This measurement represented the maximum apico-coronal extent of dye penetration in millimeters (Fig. 1k). All the data was recorded systematically in a structured data collection sheet.

Statistical analysis was performed using SPSS for Windows, Version 25.0 (IBM Corp., Armonk, NY, USA). The normality of data distribution was assessed using the Shapiro–Wilk test. Homogeneity of variances among the four groups was evaluated using Levene’s test, which confirmed that the assumption of equal variances was satisfied (F = 0.755, p = 0.391). Consequently, one-way ANOVA was employed to compare the sealing ability among the four experimental groups, followed by Tukey’s HSD post hoc test for pairwise comparisons. Intra-examiner repeatability was assessed by repeating the measurements after two weeks, and repeatability was quantified using the intraclass correlation coefficient (ICC). A p value < 0.05 was considered statistically significant.

Results

A total number of 72 specimens were used in the analysis. Intra-examiner reliability revealed excellent levels of agreement, which gave an Intraclass Correlation Coefficient (ICC) of 0.94. The descriptive statistics (mean and standard deviation) of sealing ability in the four groups are shown in Table 1. One-way ANOVA revealed a statistically significant difference in the mean dye penetration, indicating that sealing ability was not uniform among the groups (p < 0.001). The Post hoc Tukey’s analysis showed no significant difference between Geristore dry (0.64 ± 0.42 mm) and Geristore wet (0.65 ± 0.32 mm) [p = 1.00], suggesting that environmental conditions did not affect its sealing ability. However, MTA in dry condition (0.47 ± 0.21 mm) performed signficantly better than MTA in wet condition (1.13 ± 0.26 mm) [p < 0.001] as shown in Table 2.

Table 1.

Comparison of sealing ability assessed using dye penetration method among the study groups.

Groups	n	Mean ± SD (mm)	p value
Geristore dry	18	0.64 ± 0.42a	<0.001*
Geristore wet	18	0.65 ± 0.32a
MTA dry	18	0.47 ± 0.21a
MTA wet	18	1.13 ± 0.26b

*One-Way ANOVA was applied.

*p < 0.05 was considered as statistically significant

n = number of teeth per group.

Superscript letters denote homogeneous subsets based on Tukey’s HSD post hoc test (Table 2); means sharing the same superscript letter do not differ significantly (p > 0.05), while means with different letters differ significantly (p < 0.05).

SD standard deviation.

Table 2.

Pairwise comparison between groups (post hoc test).

Comparison	Mean difference (mm)	SE	p value	95% CI
Geristore dry vs Geristore wet	–0.011	0.103	1.000	–0.284 to 0.261
Geristore dry vs MTA dry	0.167	0.103	0.374	–0.105 to 0.440
Geristore dry vs MTA wet	–0.490	0.103	<0.001*	–0.763 to -0.218
Geristore wet vs MTA dry	0.179	0.103	0.316	–0.093 to 0.452
Geristore wet vs MTA wet	–0.479	0.103	<0.001*	–0.752 to -0.206
MTA dry vs MTA wet	–0.658	0.103	<0.001*	–0.931 to -0.386

Sign * denotes statistical significance (p < 0.05).

SE standard error, CI confidence interval, MTA mineral trioxide aggregate.

When comparing Gersitore with MTA, it was observed that out of the four study groups, only MTA placed in wet conditions had significantly higher dye penetration (p < 0.001), whereas the rest of the three study groups demonstrated no statistically significant difference in the penetration of the dye (p > 0.05) [Fig. 2].

Fig. 2. Box-and-whisker plots showing linear dye penetration of Geristore and MTA under dry and saliva-contaminated conditions.

Reported p values are from post hoc comparisons; *sign denotes statistical significance (p < 0.05).

Discussion

The success of endodontic microsurgery depends largely on achieving an effective apical seal, which may be compromised by contamination of the root-end cavity [1, 6, 15]. The present study, therefore, aimed to compare the sealing ability of MTA and Geristore under dry and saliva-contaminated conditions. Both materials demonstrated comparable sealing ability in dry conditions; however, moisture significantly affected MTA, whereas Geristore maintained consistent performance irrespective of the environment.

MTA exhibited the greatest dye penetration under saliva-contaminated conditions, consistent with the findings of Pichardo et al. [12]. and Pandey et al. [1]. MTA is hydrophilic and requires moisture for hydration; however, excessive moisture may alter its water-to-powder ratio, increase porosity, and compromise marginal sealing [16]. Manual mixing may further contribute to this variability [6]. In contrast, Geristore is a dual-cure resin-modified glass ionomer that exhibits favorable marginal adaptation and dimensional stability in moist conditions [17].

Beyond sealing ability, the biological performance of both materials differs in ways relevant to periapical healing. MTA’s alkalinity and calcium hydroxide release stimulate hydroxyapatite deposition, promoting cementogenesis and hard-tissue healing, findings supported by multiple histological and clinical studies [18, 19]. Geristore has demonstrated excellent fibroblast attachment and soft-tissue compatibility, attributed to its resin-ionomer surface chemistry [10]. However, evidence regarding its hard-tissue healing potential is more limited and mixed; histological evaluation of Geristore in furcal perforation repair has shown inflammatory infiltrate and an absence of cementum regeneration, in contrast to MTA’s more consistently reported osteoinductive potential [13, 20]. These differing biological profiles suggest that while both materials demonstrate acceptable biocompatibility, MTA appears more favorable for promoting hard-tissue healing, whereas Geristore’s biological advantage lies primarily in soft-tissue adaptation, indicating the two materials may be biologically complementary rather than directly interchangeable.

Although newer calcium silicate-based materials, including Biodentine, EndoSequence BC RRM, and TotalFill BC RRM, offer improved handling characteristics compared with conventional MTA, studies evaluating their sealing performance have generally reported comparable outcomes. MTA was therefore selected as the comparator in the present study because it has the most extensive laboratory, histological, and long-term clinical evidence among calcium silicate-based root-end filling materials, making it the most appropriate reference material for an investigation focused on sealing ability [21].

Contrary to our findings, several studies have reported no significant influence of moisture on the sealing performance of MTA or have demonstrated superior performance of MTA under contaminated conditions [22–25]. These discrepancies may reflect methodological differences, including contamination models, leakage assessment techniques, and irrigation protocols. For example, Hirschberg et al. [26] evaluated bacterial leakage rather than saliva contamination, while other studies employed fluid filtration methods or different irrigants, such as EDTA and chlorhexidine, which may alter dentin surface characteristics and influence material adaptation [24, 25, 27, 28]. In the present study methylene blue dye was selected because it is inexpensive, non-toxic, highly sensitive, and widely used for evaluating microleakage. However, owing to its small molecular size, it may overestimate leakage and does not necessarily correlate with bacterial penetration or three-dimensional marginal adaptation [29]. Therefore, although suitable for standardized in vitro comparison, dye penetration should be interpreted as an indirect measure of sealing ability.

The observed differences in dye penetration suggest differences in sealing performance, which may influence microbial ingress and subsequent periapical healing. Nevertheless, successful endodontic microsurgery also depends on surgical technique, host response, and long-term material stability [30]. Consequently, these findings should not be interpreted as direct predictors of clinical success and require validation through clinical studies.

The strengths of this study include standardized specimen preparation, blinded outcome assessment, and quantitative ImageJ-based analysis, which enhanced reproducibility and minimized measurement bias. However, several limitations should be considered. As an in vitro study, it could not reproduce dynamic oral conditions such as thermal cycling and occlusal loading. Artificial saliva was selected as a standardized and reproducible moisture-contamination model to isolate the effect of moisture on sealing ability. In contrast, blood contains proteins and cellular components that may independently influence material setting and marginal adaptation, making it difficult to evaluate the effect of moisture alone [31]. Nevertheless, because blood is the predominant contaminant encountered during endodontic microsurgery, future studies should incorporate blood-contamination models to further enhance clinical relevance. The dye penetration method offers only a two-dimensional assessment of sealing ability and does not account for three-dimensional leakage pathways around the root-end filling, necessitating cautious interpretation of the findings. Positive and negative control groups, which could have provided the maximum and minimum extent of leakage, respectively, were not included in our study. However, the primary aim was comparative evaluation under standardized conditions rather than the determination of absolute leakage values. In addition, since the focus of the study was physicochemical sealing ability, stem cell–based or other cell-based assays evaluating biological interactions between the root-end filling materials and cells were not undertaken.

Future studies should evaluate Geristore under blood-contaminated conditions, incorporate advanced imaging techniques and biological assessments, and compare its performance directly with newer calcium silicate-based bioceramic materials.

Conclusion

Within the context of this study, Geristore maintained a stable sealing capacity with no significant difference between the dry and saliva contamination conditions with respect to the amount of dye penetration. Also, MTA maintained a sealing ability comparable with that of Geristore when it was used in a dry environment, but it significantly forfeited this ability when it came into contact with saliva contamination. Of all materials used, MTA wet showed a superior amount of dye penetration, meaning it was most vulnerable to contamination. Therefore, Geristore could be a more dependable root-end filling material when a root end cannot be completely isolated and protected from moisture contamination. Further clinical validation is recommended to confirm these outcomes.

Author contributions

BF: Conception, study design, data collection, statistical analysis, interpretation of the results, drafting of the manuscript. FRK: Critical revision and final approval of the manuscript.

Competing interests

The authors declare no competing interests.