The Sealer Penetration into the Dentinal Tubules: An Appraisal of Different Irrigation Systems: Original Research.

INTRODUCTION: A good endodontic sealer aids in a successful root canal treatment. Sealer in turn depends on the thorough irrigation technique and debris removal. Hence, in the present study, we intend to compare the sealer's dispersion into dentinal tubules of the different irrigation systems by confocal laser scanning microscopy (CLSM).
METHODOLOGY: Seventy-six single-rooted, freshly removed human mandibular premolars were taken. They were separated into equal groups as conventional endodontic needle irrigation system, Endovacirrigation, Endoactivator irrigation, and manual dynamic agitation groups. Protaper rotary system was used and obturation was done with gutta-percha. The sealer used was AH Plus labeled with fluorescent dye (0.1% Rhodamine B isothcyanate). Transverse sections from the root apex at the levels of 1 mm, 3 mm, and 5 mm were scanned using CLSM. The sealer's penetration for the depth and the percentage were measured.
RESULTS: We observed that endovac irrigation system showed maximum percentage and depth of sealer's penetration compared to endoactivator, manual dynamic agitation, and conventional methods at 1, 3, and 5 mm levels from the apex.
CONCLUSION: The irrigation systems significantly influence the penetration of the Sealer into root dentinal tubules. When penetration of sealer at different levels, compared to endoactivator, manual dynamic agitation, and conventional method, significant greater levels were attained with the EndoVac system. Copyright:

INTRODUCTION

Elimination of the infection from the root canal marks the success of the endodontic treatment.[1] Irrigation of the root canal is an inherent part of the debridement.[2] Sodium hypochlorite is the most frequently used irrigant used for the endodontic treatments as it dissolves organic substances. It also acts as an effective antimicrobial agent. When used along with ethylenediaminetetraacetic acid (EDTA), sodium hypochlorite removes predentin, the pulp tissue, and smear layer.[3] For the effective action of the irrigants, they have to completely wet the entire surface of the root canal. Various factors influence the irrigant action including the delivery systems.[4] Various techniques have been proposed for the delivery to the root apex, the irrigant solutions.[5] The Endovac an apical negative pressure irrigation device.[6] The EndoActivator is a sonically driven canal irrigation system.[7] Repeated insertion of a well-fitting gutta-percha cone to working length of already shaped canal is used in the manual dynamic activation.[4] The most commonly used endodontic irrigation system is the conventional needle technique is that comprises administration of an irrigant through needles of different gauges into a canal, either passively or by agitation.[8] Hence, in this study, the effect of the EndoVac, Endoactivator, manual dynamic agitation irrigation, and conventional endodontic needle irrigation in the penetration of sealer inside the root dentine tubules is compared using confocal laser scanning microscope (CLSM).[1]

METHODOLOGY

Seventy-six freshly removed human mandibular premolars with radiographically confirmed straight mature roots with single canals without any other pathology were used in this study. Later, these teeth were decoronated to achieve the root length to 14 mm from the actual root apex. Working lengths were established. Later, the root ends were dried out and glue was used to seal. We randomly divided the teeth into four equal investigational groups based on the irrigation methods as the conventional needle irrigation, EndoVac irrigations system, Endoactivator irrigation, and manual dynamic agitation groups. Protaper (Dentsply Maillefer) was used for the instrumentation and the canal was enlarged to F3 in the crown-down technique. The canals in the conventional irrigation group were flooded with the help of a syringe and 28Gneedle that is vented at side (Max-i-Probe; Dentsply Rinn, Elgin, IL).[2] Sodium hypochlorite (5.25%), 1 mL was irrigated after every instrumentation. Later, the irrigants were flooded without binding to the canal. The needle was always kept 2 mm away from the working length. About 17% EDTA after 5.25% NaOCl for 30 s was used once the procedure of root canal treatment was done and the same was repeated for one more time. In the group of the EndoVac irrigation method, micro and micro irrigation methods in an up and down motion for three cycles were employed. In this at the canal opening, the master delivery tip was placed and 1 mL, 5.25% NaOCl solution was continuously supplied. In the second cycle, 17% EDTA was used. In the canals for the Endoactivator group, 1 mL 5.25% NaOCl after each instrumentation, were used to irrigate, care was taken not to bind to the rootcanal wall and be 2 mm short of the working length. For each cycle of 30 s trailed by washing with 17% EDTA repeatedly, with the final step using the 25/0.04 noncutting polymer tip of the EndoActivator, located 2 mm from the working length for 30 s for each irrigant solution was deployed. For the group of the manual dynamic agitation, sodium hypochlorite (5.25%), trailed by 17% EDTA was each activated for 1 min by the push-pull strokes for estimated rate of hundred strokes per minute for 30 s. After the irrigation, absorbent paper points (DiadentGroupInternational Inc., Chongju, Korea) were used to dry out the root canal. Later, the AH PLUS sealer (DentsplyDeTrey, Konstanz, Germany) was applied. Lateral compaction was used for placing the gutta-percha. Fluorescent Rhodamine B isothiocyanate (0.1%) (BereketChemicalIndustry, Istanbul, Turkey) was mixed with AH plus sealer, for CLSM fluorescence. A temporary material (Cavit; 3M ESPE, Seefeld, Germany) was used for the coronal filling. Later, teeth were stowed in an incubator at 37°C and absolute humidity for a week allowing the setting of the sealer. The teeth were cut to a thickness of 1 mm perpendicular to its long axis by a water-cooled, slow-speed by a microtome saw (MinitomStruers) of 0.3-mm at the 1, 3, and 5 mm from the apical end. Abrasive papers of the silicon carbide were used to polish the sections. Later, the sectioned specimen was examined under CLSM (NikonAir, Eclipseti, NiselementsVersionAr4, Japan) at ×10 enlargement. The depth of sealer's penetrance was measured as the average penetration into the dentine, calculated using the straight-line tool of Image software, at eight standardized points beginning from the inner side of the canal wall at 1, 3, and 5 mm from the apical end. In addition, the point of deepest penetration was calculated from canal wall to point of greatest depth penetrance of sealer. The percentage of penetrance of the sealer was measured from the rhodamine B–stained surfaces of the canal wall where sealer penetrated into dentin tubules “sealer tags” and dividing these values by the circumference of the root canal itself and multiplying the result by 100. Furthermore, the integrity of the sealer layer perimeter was assessed on every image taken by calculating the rhodamine-stained perimeter of the canal wall and dividing this value for the canal circumference, and given as percentage. Statistical analysis was done for the greatest depth the sealer had penetrated and percentage of sealer's penetrance. ANOVA TEST followed with post hoc analysis by Bonferroni were performed. P < 0.05 was considered statistically significant.

RESULTS

It was observed in the present study that the sealer's penetrance depth through conventional method, EndoVac, EndoActivator, and manual dynamic agitation irrigation technique were seen maximum at 5 mm. From the apical end at 1 mm, ANOVA, and Bonferroni test showed that EndoVac and Endoactivator systems had significantly greatest depth of sealer's penetrance compared to conventional and manual techniques. However, at 3 mm and 5 mm levels EndoVac had significantly higher depth of sealer penetration compared to group others [Tables 1 and 2]. We observed that from the apical region at 1 mm, ANOVA test and post hoc analysis by Bonferroni test showed that EndoVac having significantly higher percentage of sealer penetration compared to other groups. However at 3 and 5 mm from apical ends, both EndoVac and endoactivator showed maximum percentage of penetration compared to conventional needle irrigation and manual dynamic agitation irrigation methods [Figures 1 and 2].

Table 1

Comparison of the depth of sealer’s penetrance using various irrigation systems

	n	SD	Mean	95% CI for mean		Repeated measures ANOVA F	P
				Lower bound	Upper bound
Conventional needle technique
1 mm distance	21.78	20	304.10	293.91	314.29	1355.657	0.000
3 mm distance	42.15	20	548.07	528.34	567.79
5 mm distance	23.42	20	754.60	743.64	765.56
Endovac irrigation system
1 mm distance	36.76	20	426.15	408.95	443.35	1654.846	0.000
3 mm distance	42.60	20	892.18	872.24	912.12
5 mm distance	44.76	20	992.99	972.05	1013.94
Endoactivator group
1 mm distance	43.19	20	442.96	422.75	463.17	989.178	0.000
3 mm distance	29.69	20	721.32	707.42	735.21
5 mm distance	43.13	20	943.40	923.21	963.59
Manual dynamic agitation
1 mm distance	38.45	20	345.55	327.56	363.54	436.671	0.000
3 mm distance	42.09	20	602.30	582.60	622.00
5 mm distance	55.03	20	770.45	744.70	796.20

SD: Standard deviation, CI: Confidence interval

Table 2

Post hoc analysis by Bonferroni test for the depth of sealer penetration using various irrigation systems

	Mean difference	Standard error	P
1 mm distance
Conventional needle technique
Endovac irrigation system	−122.05	11.37	0.000
Endoactivator group	−138.86	11.37	0.000
Manual dynamic agitation	−41.45	11.37	0.003
Endovac irrigation system
Endoactivator group	−16.81	11.37	0.860
Manual dynamic agitation	80.60	11.37	0.000
Manual dynamic agitation	97.41	11.37	0.000
Endoactivator group
3 mm distance
Conventional needle technique
Endovac irrigation system	−344.11	12.49	0.000
Endoactivator group	−173.25	12.49	0.000
Manual dynamic agitation	−54.23	12.49	0.000
Endovac irrigation system
Endoactivator group	170.86	12.49	0.000
Manual dynamic agitation	289.88	12.49	0.000
Endoactivator group
Manual dynamic agitation	119.02	12.49	0.000
5 mm distance
Conventional needle technique
Endovac irrigation system	−238.39	13.64	0.000
Endoactivator group	−188.80	13.64	0.000
Manual dynamic agitation	−15.85	13.64	1.000
Endovac irrigation system
Endoactivator group	49.59	13.64	0.003
Manual dynamic agitation	222.54	13.64	0.000
Endoactivator group
Manual dynamic agitation	172.95	13.64	0.000

SE: Standard error

Figure 1

Comparison of the percentage of penetration using various irrigation systems

Figure 2

Comparison of the percentage of penetration at various levels

DISCUSSION

The resistant seal between the core material and root canal's wall is accomplished by a root canal sealer. The sealer/dentin interface as great as possible is required for a successful root canal therapy.[9] It has been noted that there are many factors that influence the root dentin penetration for a sealer; one among them is the flow. This, in turn, is under the influence of the size of the sealer particles, uniformity, shear rate, time and temperature, etc.[10] We have taken care to keep the factors of the time and temperature constant in an attempt to avoid error in this study. Smear layer was not observed in our study. Instead, we observed the penetration inside dentin tubules of the sealer employing the CLSM.[11] The apical end was enlarged to the size of 40/04 for all the specimens. The sealer that was employed was AH PLUS. In the present study, conventional endodontic needle, Endovac, Endoactivator, and manual dynamic agitations were used to evaluate the sealer's penetrance in dentin tubules at the apical, middle, and coronal thirds. It has been shown through various studies that in smear layer's removal, the irrigation system EndoVac was effective[121314] [Figures 3 and 4]. In the study done by Nielsen, this system was shown to remove from the apical end the debris and lower sodium hypochlorite extrusion from the apex when compared to the conventional method.[26] In the present study, endovac showed better sealer penetration in all the three segments, this could be comparable to the result of Turncer.[1] We compared the various irrigation systems at various depths of the root canal for the sealer penetration. We observed that EndoVac had a higher penetration percentage for the AH PLUS when compared to the other systems at all the levels of the root canal. This could be because of the efficient debris removal, especially in the apical third using EndoVac systems. This system using the negative pressure helps in the continuous flush of the canal till the working length with the fresh irrigant and thus avoiding the air entrapment. This is again aided by the vents in the microcannula that helps in the removal of the debris.[14] When compared to the conventional and manual irrigation the Endoactivator exhibited a greater percentage and greatest depth of sealer's penetrance at all the levels of the root canal in our study. This irrigation system is sonic-driven system that generates a hydrodynamic phenomenon by activating intracanal reagents. Manual compared to the conventional system of irrigation was better in the sealer penetration properties were observed in our study at the different levels of the root canal. In the study of Saber,[4] the outcome of the different irrigation systems for the smear layer's removal was evaluated. They noticed that when compared to conventional irrigation, the methods that employed negative pressure at the apex and manual dynamic agitation showed better performance. This can be attributed to the ability of these two systems reaching the full working length for the root canal which is not attained with the conventional methods for the irrigation. However in the study conducted by Howard et al.[13] when the three systems PiezoFlow, EndoVac, and Max-i-Probe were compared at 2 and 4 mm from the apical level for the debris removal there was no significant difference observed. They concluded that rather than the system of the irrigation, the volume and the depth of the irrigant were vital. In other study also it was observed that conventional system has less sealer penetration. From the earlier studies, it can be concluded that the conventional method of irrigation was only effective till the middle of the root canal when compared to the apex, that could be due to the prevention of the irrigant reaching the full working length called the vapor lock effect,[15] or the position of the needle short of 2 mm from the working length to prevent irrigant extrusion.[214] This statement has been not thoroughly established.[151617] We also observed in our study that the sealer penetration was least for the conventional method at the 1 and 3 mm from the working length. In our study, when using all the four irrigation systems the greater sealer penetration was established at the 5 mm level. This is in unison with the other studies that used various irrigations and for an epoxy resin sealer at the various levels of the root canal.[1819] Previous studies have established that the sealer's penetration and the antibacterial activity are in proportion, hence exerting a beneficial effect for the root canal.[20] Although the endodontic sealer may or not directly act on the bacteria, it may act as a barrier for the penetration of the infection-causing agents into the dentinal tubules. The intratubular penetration for AH Plus sealer was better visualized with the CLSM technology. We observed that when the different techniques were used the sealer was seen to penetrate the tubules of the root dentin, though there was no continuous layer was seen. In our study, the maximum sealer penetration was seen at 5 mm for all four irrigation systems. Our observation is in unison with the study of Weis and Parashos.[21] We chose CLSM and the Rhodamine B fluorescence because it aids in better conception of the sealers adaptation and the depth of penetration in horizontal sections.[22] We took all precautions for the avoidance of bias. The results of our study are in accordance with the previous studies where we also observed a gradually increase of the sealer penetration from the apex to the coronal end.[23242526]

Figure 3

EndoVac group

Figure 4

Obturation radiographs and confocal laser scanning microscopic images

CONCLUSION

It can be concluded from our study that the sealer's penetration in terms of the depth and the percentage using the EndoVac irrigation was significantly better compared to Endoactivator, manual dynamic agitation, and conventional systems at various levels of one, three, and 5 mm from the apical ends. The irrigation techniques have been shown to influence the sealers ability to penetrate the lengths of the root canal, which generally is seen to be decreasing with the apical progression. In our study, we found that the four irrigation techniques used, failed to be consistent in the adaptation for the entire surface of the root canal. Further studies are warranted to analyze the entire canal rather than a portion with bigger sample size as these factors may be important in future successful endodontics.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.