Keywords AH Plus bioceramic sealer - calcium silicate - HEDP - push-out bond strength - TotalFill
Introduction
Effective root canal treatment requires thorough cleaning and shaping. Sodium hypochlorite
is considered the gold standard irrigation solution in endodontics due to its disinfecting
properties and ability to dissolve necrotic tissues.[1 ] Other irrigation materials are used to supplement the action of sodium hypochlorite,
including ethylenediaminetetraacetic acid (EDTA), chlorohexidine, MTAD, and Q mix
(a premixed solution of EDTA, chlorhexidine, and a detergent).[2 ]
EDTA is a chelating agent used in conjunction with sodium hypochlorite to dissolve
the inorganic root canal material and remove the smear layer created by mechanical
root canal preparation.[2 ] It is used in the final irrigation step to enhance the cleaning efficiency of sodium
hypochlorite, create open dentinal tubules, distribute the biofilm that will eventually
facilitate the irrigation action, and improve the obturation.[1 ]
A new concept of continuous chelation by weak acids has recently gained more attention.
It involves using a weak chelating agent etidronic acid or 1-hydroxyethylidene-1,1-diphosphonic
acid (HEDP)[3 ] with sodium hypochlorite. It is proposed that it will continuously remove the smear
layer and enhance the efficacy of the irrigation process.[4 ] On the other hand, it was shown that HEDP (Dual Rinse, HEDP, Medcem Weinfelden,
Switzerland) has less erosive effect on dentin surface than EDTA.[5 ] Also, it showed a better bioceramic sealer penetration compared to EDTA and was
shown to be the most effective irrigation against Enterococcus faecalis .[6 ]
EDTA, on the other hand, has a potentially harmful effect on sodium hypochlorite antibacterial
and dissolving activity if used simultaneously, as EDTA depletes the action of chloride
ions and can cause excessive erosion to dentinal tubules.[7 ]
[8 ] On the contrary, the HEDP was tested compared to sodium hypochlorite and was found
to chelate Ca2+ ions effectively. At the same time, the cytotoxicity and genotoxicity were dictated
by the presence of free available chlorine.[9 ]
The effects of these materials on the bonding of newer obturation materials, particularly
bioceramics, are currently under investigation.[10 ] Bioceramics are dental materials used to fill and seal root canal systems. Understanding
how irrigation solutions and chelating agents interact with bioceramics is crucial
for optimizing the success of root canal treatments.
The AH Plus bioceramic sealer (APB; Dentsply Sirona, Charlotte, North Carolina, United
States) is a relatively new calcium silicate-based sealer known for its rapid setting
time, lower solubility, reduced film thickness, and higher radiopacity compared to
the EndoSequence BC sealer (Brasseler, United States). The composition of APB includes
50 to 75% zirconium dioxide, 5 to 15% tricalcium silicate, 10 to 30% dimethyl sulfoxide,
less than 0.5% lithium carbonate, and various thickening agents.[11 ]
[12 ]
On the other hand, the TotalFill bioceramic sealer (TFB; FKG Dentaire, La Chaux-des-Fonds,
Switzerland) consists of 20 to 35% tricalcium silicate, 7 to 15% dicalcium silicate,
calcium phosphate, colloidal silica, 1 to 4% calcium hydroxide, and 35 to 45% zirconium
oxide as a radiopacifier, along with hydroxyapatite.[12 ] TFB has been researched for its push-out bond strength (POBS), biocompatibility,
mineralization potential, physicochemical properties, cytotoxicity, and volumetric
changes.[13 ]
[14 ]
[15 ]
This bioceramic sealer features a H2 O-free thickening agent that enhances flowability, making it premixed and ready for
injection into root canals.[16 ] Various methods have been employed to test the properties of these materials, including
evaluations of physicochemical characteristics, setting reactions, and POBS.[11 ]
[14 ]
[15 ]
[17 ]
The push-out test is highly regarded as it closely simulates clinical conditions,
offering greater accuracy in measuring bond strength with minimal premature failures.[18 ] POBS is a strong indicator of the long-term retention of dental materials within
the tooth structure. Higher POBS values suggest better adhesion, which improves the
durability of restorations and endodontic fillings.[19 ] Materials with higher POBS can better withstand the forces of mastication and thermal
changes in the oral environment. This improved stress distribution helps maintain
the integrity of the restoration or endodontic filling, reducing the likelihood of
fractures or gaps forming between the material and tooth structure.[20 ] When interpreting POBS results for clinical application, practitioners should consider
the specific dental material being used (e.g., different sealers or composites), the
tooth structure involved (e.g., coronal vs. radicular dentin), the presence of contaminants
like blood, which can significantly affect bond strength,[19 ] and long-term factors such as thermal cycling and masticatory loading which can
impact bond strength over time.[20 ]
To the authors' knowledge, no study has evaluated the bond strength of apical plug
bioceramics (APB) to root dentin under various irrigation protocols. Therefore, this
study aims to investigate the effects of different irrigation methods: sodium hypochlorite
alone, sodium hypochlorite combined with EDTA, and sodium hypochlorite combined with
HDEP. We will also assess their interactions with newly introduced bioceramic sealers.
The null hypothesis states that neither the different bioceramic materials nor the
irrigation protocols will affect the bonding strengths to root canal dentin.
Materials and Methods
Sample Size Calculation
The sample size calculation was based on the result of Paulson et al.[21 ] Accordingly, the sample size should be a minimum of eight samples in each group
(power = 0.95, effect size = 0.9, significance level = 0.05)—a total of 60 teeth (10
samples in each group) with a 20% dropout. The ethical approval was granted by the
IRB Committee at Jordan University of Science and Technology, Jordan (IRB ethical
approval Ref-IRB/23/2017).
Preparation of Sample
A pilot study was conducted ahead of the study with 10 teeth using the proposed methodology.
The pilot study helps refine the protocol by avoiding voids in the obturated canals
as no gutta-percha (GP) was used, ensuring standardization of the sample's parameters,
and verifying canal lumen diameter with the POBS plugger head size compatibility.
A single operator conducts all the aspects of the study. A total of 60 human maxillary
central incisors were collected after extraction for periodontal reasons. Teeth were
cleaned and preserved in phosphate-buffered saline in an incubator at a controlled
body temperature; the solution was refreshed every week until the time of the study.
Later, teeth were decorated at the level of cementoenamel junction until a standardized
root length was achieved at 15 mm using a water-cooled diamond wafering blade (Horico,
Berlin, Germany).
The root canal was prepared using the ProTaper Gold system (Dentsply Sirona Endodontics,
Tulsa, Oklahoma, United States) up to size F5 according to manufacturer instruction
to the entire working length and apically further enlarged by introducing the file
3 mm beyond the apical constriction to enlarge the canal up to ISO standard size #65,
this step was made to ensure the consistency with the POBS pluggers at the apical
area. The apices of all specimens were then sealed using sticky wax to prevent irrigation
flow throughout the apical foramina and randomly divided into three groups (n = 20) depending on the final irrigation protocol.
NaOCl group (Group NS) : canals were irrigated after each sequential instrumentation with 5 mL of 5.25% NaOCl
(CHLORAXID 5.25%; PPH CERKAMED, Stalowa Wola, Poland) using a 27-G side-vented needle
(Vista Dental Inc., Racine, Wisconsin, United States) that was set at 2 mm short of
the working length. The irrigation needle was moved upward with an amplitude of 2 mm
to agitate the solution. For the final irrigation, 5 mL NaOCl (5.25%) was applied
for 1 minute, followed by rinsing with 5 mL of distilled water for 1 minute.
NaOCl/EDTA group (Group NE) : similar to Group NS, except for the final rinse, for which 5 mL of EDTA (17%) (i-EDTA,
i-dental, UAB, Šiauliai, Lithuania) was applied for 1 minute before rinsing the canals
with 5 mL of distilled water for 1 minute.
NaOCl/HEDP group (Group NH) : canals were irrigated while conditioning the smear layer at the preparation stage
with a capsule of 9% dual rinse HEDP mixed with 10 mL of 5.25% NaOCl (CHLORAXID, Poland)
at room temperature. The solution was used with a 27-G side-vented needle; the treatment
time was standard to 5 minutes for all groups; the HEDP was provided as a powder,
which was mixed with NaOCl as per manufacturer's instruction for 2 minutes before
use, followed by a final rinse with 5 mL distilled water for 1 minute.
In each group, samples were subdivided randomly into two groups based on the sealer
type: TFB or APB. Before obturation, canals were dried using matching paper points
(Dentsply Sirona Endodontics, Tulsa, Oklahoma, United States). According to their
assigned groups, the sealers were applied into the canals using designated injecting
tips assisted by sonic activation (EasyinSmile, Passaic, New Jersey) to disperse them.
Radiographs were obtained from the proximal and labial aspects to ensure proper filling
of the canals without voids. Teeth were temporarily filled with Cavit (3M ESPE, St.
Paul, Minnesota, United States) and stored in an incubator at 37°C and 100% humidity
for 2 weeks to allow the complete setting of the sealers.
After storage, the roots were embedded in cold-cured acrylic. Roots were then sectioned
using a water-cooled precision saw IsoMet 1000 (Buehler, Lake Bluff, Illinois, United
States) at three different levels: apical measure (3–6 mm above root tip), middle
(6–9 mm above root tip), and coronal (9–12 mm above root tip), to obtain three slices
of 3 ± 0.2 mm thickness, discarding the apical 3 mm (0–3 mm above root tip).
Push-Out Bond Strength Measurement
For each root section, the greatest and least diameters of the canal were measured
on both sides (coronal and apical), and the thickness was measured using a digital
caliper (Vogal, Kevelaer, Germany). The bonded surface area was calculated using the
following formula[14 ]:
where D 1: greatest canal diameter, D 2: least canal diameter, µ = 3.14, and h is the thickness of the root slice.
Each section was placed in the universal test machine (WDW-20, Jinan Testing Equipment
IE Corporation, China). Vertical load was applied over the filling materials in an
apical-coronal direction with a crosshead speed of 1 mm/min using three indenters
with different sizes (1, 0.7, and 0.5 mm) corresponding to each section, coronal,
middle, and apical, respectively. The maximum load at which the material was dislodged
was recorded in Newton (F-Max). Accordingly, the POBS was drawn in megapascal (MPa)
using the following equation:
Examining the Mode of Failure
Root sections subjected to the push-out test were examined under 40x magnification
using an optical microscope (Olympus, Tokyo, Japan) to determine the failure mode.
The mode of failure was classified as follows:
Adhesive failure between the root canal dentin wall and sealer interface.
Cohesive failure within the sealer.
Mixed: adhesive and cohesive modes (some material left attached to the dentin surface).
Scanning Electron Microscopy
Two specimens from each subgroup were randomly selected for scanning electron microscopy
(SEM) analysis. This step was added to help understand the result obtained from POBS.
Each sample was cut in half using a metal chisel and rinsed with 99% ethanol. It was
then air-dried, mounted on the metallic cylinder, and finally sputter-coated with
an ultra-thin coating of gold alloy (Q150R ES sputter coater, Quorum Technologies,
United Kingdom). Examination under the microscope was performed at a magnification
range of 1,200 to 2,400x (Quanta FEG 450, FEI, The Netherlands).
Statistical Analysis
The data were analyzed using IBM SPSS software Version 27, employing descriptive statistics
to compute the push-out, mean, and standard deviation values. A histogram of the residuals
was created to assess the data's normality and compare means across different groups.
A two-way analysis of variance (ANOVA) was conducted to evaluate the effects of the
sealer type and irrigation solutions. At the same time, an independent t -test was utilized to compare the means between the different sealers. A p -value of less than 0.05 was deemed statistically significant for both tests.
Results
Push-Out Bond Strength
The results of the POBS test of all the groups are shown in [Table 1 ]. The two-way ANOVA test revealed that the sealer type had a highly significant effect
on the POBS (p < 0.05), unlike the irrigation protocol (p > 0.05), with no significant interaction between the two.
Table 1
Push-out bond strength (MPa; mean ± SD) for the two materials tested with different
irrigation on the dentine surface
NE
NH
NS
TFB[a ]
12.2 ± 1.83
12.4 ± 2.01
11.8 ± 1.85
APB
0.86 ± 0.31
0.56 ± 0.23
0.95 ± 0.31
Abbreviation: SD, standard deviation.
Note: Two-way ANOVA revealed that there is no significant interaction between the
two parameters.
a TFB shows significantly higher push-out bond strength than the APB regardless of
the irrigation protocol (p < 0.05).
Furthermore, since the sealer type had a significant POBS, an independent t -test was done as a comparison test at 95% confidence intervals; the independent t -test analysis showed that TFB, regardless of irrigation protocol (12.1 ± 0.25 MPa),
had a significantly higher bond strength to radicular dentine than APB (0.79 ± 0.26
MPa) (p < 0.05).
Further analysis of the TFB groups using a one-way ANOVA test and post-hoc comparison
revealed that both NE (12.2 ± 1.83 MPa) and NH (12.4 ± 2.01 MPa) irrigation protocols
exhibited a comparable effect on the POBS. In comparison, NS (11.8 ± 1.85 MPa) was
associated with a lower POBS although not significant (p > 0.05). For the APB sealer, however, the highest strength was associated with the
NS group (0.95 ± 0.36 MPa), although it was not significantly higher than group NE
(0.86 ± 0.31 MPa) (p > 0.05) and group NH (0.56 ± 0.23 MPa) (p < 0.05).
[Table 2 ] presents the POBS of both materials at different levels. The results show no consistency
in the POBS values and the section level. TFB has the highest POBS at the coronal
level in the NS group (14.8 ± 5.60 MPa) and the lowest in the NS group at the apical
level (9.66 ± 3.09 MPa). As for the APB, the highest was in the NS group at the apical
(1.65 ± 1.61 MPa) and the lowest in the NH group at the middle (0.49 ± 0.18 MPa).
Table 2
Mean ± SD (MPa) of the push-out bond strength for each tested material at different
levels
Root section
NS
NE
NH
APB
TFB
APB
TFB
APB
TFB
Coronal
0.99 ± 1.16
14.8 ± 5.60
0.79 ± 0.58
9.73 ± 2.96
0.64 ± 0.43
11.6 ± 4.38
Middle
0.91 ± 1.11
10.1 ± 4.09
1.07 ± 0.87
13.7 ± 2.71
0.49 ± 0.18
13.3 ± 6.38
Apical
1.65 ± 1.61
9.66 ± 3.09
0.75 ± 0.59
14.5 ± 4.28
0.53 ± 0.28
12.3 ± 5.21
Abbreviations: APB, AH Plus Bioceramic; TFB, TotalFill Bioceramic.
Mode of Failure
A variation in the mode of bond failure between the sealers and the radicular dentine
was noticed. The percentage of each mode of failure associated with the two sealers
and the different protocols of final irrigation is presented in [Table 3 ]. Most of the samples exhibited a mixed mode of failure regardless of the irrigation
protocol (>65%). Interestingly, no adhesive failures were observed in the TFB group.
On the other hand, APB had few adhesive failures observed when NS or NE was used (≈30%),
and the least adhesive failure (13%) was associated with group NH. Remarkably, the
TFB group showed a higher rate of cohesive failures than the APB groups.
Table 3
Percentage of mode of failure for the materials tested from the root dentine surface
treated with different irrigation protocols
Irrigation
Material
Mode of failure
Cohesive
Adhesive
Mixed
NS
APB
3.3%
30%
66.6%
TFB
20%
0%
80%
NE
APB
0%
33.3%
66.6%
TFB
16.7%
0%
83.3%
NH
APB
3.3%
13.3%
83.3%
TFB
26.6%
0%
73.3%
Abbreviations: APB, AH Plus Bioceramic sealer; TFB, TotalFill Bioceramic.
Scanning Electron Microscopic Examination
[Fig. 1 ] shows SEM images of the bonded dentine surface after different irrigation protocols.
The images demonstrate remnant materials attached to the dentine surface in the two
groups of sealers regardless of the irrigation protocol used.
Fig. 1 SEM of the middle part of the canal surface revealing the different root dentine
surfaces treated with NaOCl/TFB (A ), NaOCl/AHPB (B ), NaOCl/EDTA/TFB (C ), NaOCl/EDTA/AHPB (D ), NaOCl/HEDP/TFB (E ), and NaOCl/HEDP/AHPB (F ). SEM, scanning electron microscopy.
[Fig. 1(A, B) ] compares the two sealers in the NS group. The smear layer in both groups is noticeable.
TFB, compared to APB, has a spot-like sealer remnant with less spread of material
and less material thickness.
[Fig. 1(C, D) ] compares the two sealers in group NE. The majority of the dentinal tubules are filled
with a material that could be attributed to the TFB penetrating the tubules with remnants
of the sealer adhered to the dentin surface ([Fig. 1C ]). In the APB ([Fig. 1D ]), no remnants of the sealer were noticeable on the dentine surface, which exhibited
almost empty dentinal tubules.
[Fig. 1(E, F) ] compares the two sealers in group NH. Interestingly, the smear layer was partially
removed, and the sealers appeared to engage with it.
Discussion
Calcium silicate cements have gained a growing interest recently due to their biocompatibility,
ion release potential, and antimicrobial properties.[22 ] This has led to a wide range of clinical applications that include endodontic sealers.
Understanding their bonding capability to root dentin is crucial because proper bonding
to the root dentin will reduce fluid and microorganisms' infiltration and prevent
the dislodgment of filling material to the coronal part.[23 ]
Effective irrigation protocols are crucial for successful endodontic treatments, and
recent research has provided valuable insights into optimizing these procedures. A
comprehensive irrigation protocol typically involves the use of sodium hypochlorite
(NaOCl) as the primary irrigant, followed by 17% EDTA for smear layer removal.[24 ] The sequence and volume of irrigants are critical factors, with recommendations
suggesting copious amounts of NaOCl, followed by saline, EDTA, another saline rinse,
and a final NaOCl rinse.[25 ] When tailoring their irrigation protocols, clinicians should consider case-specific
factors, such as pulpal and periapical diagnoses. While there is no universally standardized
protocol, clinicians should stay informed about current research and adapt their techniques
based on emerging evidence to optimize endodontic outcomes. HDEP has been shown to
be effective in smear layer removal,[4 ] effectively chelate Ca2+ ions, and maintain antibacterial activity.[6 ]
[9 ] Also, HEPD was tested clinically and found safe and suitable for clinical use.[9 ]
The present study investigated the effects of different irrigation protocols on the
POBS of TFB and APB sealers. The results revealed that the irrigation protocol did
not significantly influence the POBS of either sealer (p > 0.05). For TFB, both EDTA and HEDP protocols showed slightly higher POBS values
than NaOCl alone. However, these differences were not statistically significant. Conversely,
for APB, the highest POBS was associated with NaOCl alone, followed by EDTA, with
HEDP showing the lowest values. These findings suggest that while the choice of irrigants
may subtly influence the bonding performance of bioceramic sealers, other factors,
such as sealer composition and set reactions, may play a more dominant role.
HEDP is a mild chelator that increases the antimicrobial efficacy of irrigation solution.[4 ] It has been shown to enhance the POBS with Biodentine in partial agreement with
the current study.[21 ]
[26 ] Our results, however, contrasted with those of Sfeir et al,[15 ] who reported that HEDP was associated with the least bond strength with TFB sealer.
This can be explained by the different methodologies applied and the cross-section
thickness of the samples.
Previous studies have explored the effect of dual rinse HEDP on the POBS of bioceramic
sealers and cements. In a recent study,[27 ] researchers found that HEDP did not negatively affect the POBS of bioceramic cement,
while a more recent study[28 ] reported that HEDP improved the POBS of certain bioceramic sealers. Our findings
partially align with these studies, as HEDP did not significantly reduce the POBS
of TFB. However, the lower POBS observed with APB when using HEDP contrasts with previous
findings, highlighting the need for further investigation into the specific interactions
between different bioceramic formulations and irrigation protocols.
Al-Hiyasat and Yousef[17 ] reported that removing the smear layer using EDTA was associated with a reduced
bond strength of the TotalFill putty and MTA but not for Biodentine. This contrasts
with our results. Although the same methodology was applied, this could be related
to using the putty rather than sealer, which has different wettability and viscosity;
on the other hand, the time storage in their study was shorter, which might have affected
the calcium ion exchange with the radicular dentine and subsequently the bond strength.[29 ]
The use of EDTA did not enhance the POBS compared to the other irrigation protocols;
this is in agreement with Adham and Ali,[30 ] who reported no difference between the NaOCl/EDTA and HEDP. On the contrary, Sfeir
et al[15 ] showed that NaOCl and NaOCl/EDTA irrigation protocols were associated with higher
POBS when compared to HEDP when used with TFB. In the current study, NaOCl showed
comparable results to HEDP and EDTA groups with TFB sealer.
Regardless of the irrigation method, each sealer had no statistically significant
difference in bond strength. Therefore, the presence or absence of a smear layer after
canal preparation does not significantly affect the bond strength of TFB with dentine.
This can be justified by the smear layer acting as a coupling agent, enhancing the
bond strength of the bioceramic sealers.[15 ]
[31 ]
[32 ]
Compared to APB, TFB was shown to have significantly higher POBS. This could be attributed
to the different compositions of these sealers. Upon hydration, calcium and hydroxyl
ions release can contribute to forming tag-like structures within the dentinal tubules,
which may enhance the POBS.[33 ] Atmeh et al[34 ] showed that an interfacial layer of structurally altered dentine called the “mineral
infiltration zone” can form due to the alkaline etching effect of hydrated calcium
silicate materials. This may explain the higher values of POBS recorded with TFB as
it contains a higher percentage of silicate phases (20–35%) compared to that (5–15%)
present in APB.[35 ] This can be supported by the findings of Souza et al,[11 ] in which they reported that Endosequence bioceramic sealer (a co-brand of TFB) had
higher calcium ion release than APB. The latter was also found to have greater porosity
related to the larger particle size.[36 ] On the contrary, Shieh et al[37 ] showed comparable POBS for both Endosequence BC and APB sealers. This difference
could be related to the thin sections used (0.9 mm) in their study and the sample
storage conditions.
Most of the samples exhibited mixed failure mode regardless of the irrigation protocol.
It was noticed that TFB samples exhibited no adhesive failures, with most of the samples
showing a mixed failure mode. This is in agreement with Dewi et al.[38 ] However, this result was different from Sfeir et al[15 ] and Shieh et al,[37 ] in which the authors found more cohesive failures; this can be explained by the
presence of GP core material and the thin sections used in the methodology.
In this study, canals were obturated using the sealer only without utilizing GP to
assess the bond strength between the sealer and dentin. Sealers present a stronger
bond to dentin than to the core material (GP). Additionally, the plastic deformation
of the plastic core may negatively affect the POBS.[39 ]
Bonding of the root canal sealers to dentine was studied extensively.[15 ]
[37 ]
[38 ] Chemo-mechanical preparation might affect the dentinal tubule integrity, which might
affect the interaction between the obturation materials and the root canal dentine.
This might affect the long-term seal of the root canal sealer interface and lead to
microleakage.[40 ] A lower bond strength might account for a higher possibility of future leakage and,
subsequently, lower success of the root canal treatment.[41 ]
However, it is crucial to acknowledge the limitations of the POBS test, which has
been increasingly questioned in recent literature.[42 ] The assumption that higher bond strength indicates better sealer adhesion to root
canal dentin walls is doubtful and lacks substantial evidence. This is particularly
problematic when evaluating hydraulic materials like bioceramic sealers, which form
actual chemical bonds with the dentinal surface. The POBS test, primarily a mechanical
evaluation, may not accurately represent these chemical interactions. Furthermore,
the test fails to account for the complex root canal anatomy, residual moisture, and
dynamic oral environment, all critical factors in clinical settings.
Several limitations of this study should be acknowledged. The in vitro nature of the experiment may not fully replicate the clinical conditions, including
the presence of residual pulp tissue, blood, or other contaminants that could affect
sealer adhesion. The study also focused on several irrigation protocols and sealer
types, which may not represent all clinical scenarios. Additionally, the POBS test
itself, as discussed earlier, has inherent limitations in evaluating the actual bonding
effectiveness of hydraulic materials.
Future research should focus on developing more clinically relevant testing methods
that can better evaluate bioceramic sealers' chemical interactions, sealing ability,
and long-term stability. Studies incorporating micro-computed tomography analysis
of sealer penetration, long-term leakage assessments, and biocompatibility evaluations
could provide a more comprehensive understanding of bioceramic sealer performance.
Furthermore, investigating the effects of various irrigation protocols on the hydration
and setting reactions of different bioceramic formulations could offer valuable insights
into optimizing their clinical use. Lastly, long-term clinical studies comparing the
outcomes of root canal treatments using different irrigation protocols and bioceramic
sealers are needed to validate the clinical relevance of in vitro findings.
Conclusion
APB sealer had inferior POBS compared to TFB Sealer, which might affect the long-term
stability of the dentin bonding interface and treatment outcomes with APB. The irrigation
protocols used in the study did not affect the POBS and the possible sealing ability
of the bioceramics. Smear layer removal appears not to affect the bonding strength
of the bioceramic sealers.
Based on the study results, three key conclusions can be drawn:
TFB sealer demonstrated significantly higher POBS to radicular dentin than APB sealer,
regardless of the irrigation protocol.
The irrigation protocol did not significantly influence the POBS of either TFB or
APB sealers to root canal dentin.
Mixed failure mode was most commonly observed for both sealers across all irrigation
protocols, with TFB showing a higher rate of cohesive failures than APB.
