Sealing Ability of Different Obturating Techniques in Apically Separated Rotary Files: An In Vitro Study.

Aim: Testing whether two sealant systems (cold laterally compacted gutta-percha and Obtura II) can be used with extraction across two apically separated rotational nickel-titanium files was the primary objective of this study (RACE and K3). Materials and
Methods: Both the positive and negative control teeth were randomly distributed among 62 mandibular premolars to create two groups of 30 each. Following the RACE and K3 approaches, four subgroups were created from the roots. Subgroups A1, B1, and A2, B2 (n = 10 each) were formed in the apical thirds of the canal at 3 mm from the tip. There was no division of instruments between groups A3, B3, B4, and A4. When it came to obturation, the Obtura II method was used for A2, A4, B2, B4, and A1, A3. A dye extraction process was employed to determine whether the specimens had been obliterated. Analysis of variance (ANOVA), Student t test (two-tailed, independent), and Leven's test were used to ascertain the values for each of the study groups.
Results: Group A1 had a substantially lower leakage rate than group B1. Groups A2, B2 and A3, B3 had no statistically significant differences. Group A4 had a substantially lower leakage rate than group B4.
Conclusion: Even when the cracked NiTi rotary system was not present, Obtura II-obturated groups had less leakage than the lateral condensation approach. Copyright:

INTRODUCTION

When dentists are attempting to do root canal treatment, they may face a procedural mishap called instrument separation. In the event of instrument separation, the clinical outcome gets compromised because of the failure of root canal therapy.

Because of their form memory, high elasticity, biocompatibility, and corrosion resistance, NiTi rotary files are chosen over stainless steel files. If you are looking for an alloy that can hold up better under lesser stresses, look no further than NiTi. The operator's competence and expertise, as well as the design, size, taper, flutes, and pitch length of the rotating NiTi instruments, all these factors may contribute to fracture of the file.[1]

The root canal tool may be difficult to extract if the piece cannot be found. The removal of fractured teeth has been described using a variety of methods. A fluid-tight seal can be achieved by leaving the fragment in the canal after accurate endodontic obturation.[2] The goal of this research was to evaluate the sealing capabilities of two obturation systems (gutta-percha and Obtura II) to the RACE and K3 systems by utilizing dye extraction (RACE and K3 systems).

MATERIALS AND METHODS

Sixty-two mandibular premolars used in this investigation were all with straight and single root canals. The root length was maintained at around 18 mm, and all crowns were sliced at the cemento enamel junction (CEJ) with a carborundum disc to eliminate any cracked teeth. To calculate the working length, 1 mm was taken off from the length of a #10K file and the tip was set on the highest point of the file's central axis.

In the experiment, a total of 62 roots were separated into two groups. Each group was provided with one sample and designated as the negative control and were sealed with cyanoacrylate cement. The systems RACE (FKG Dentaire) and K3 (Sybron Endo) were used to make the root canal preparation in the cases of groups A and B. These cases utilized Endo-motor X-smart (Dentsply, maker of the Maillerfer), together with Glyde File Prep (Sybron Endo) (Dentsply-Maillefer). From file #25 to #30, the root canal preparation was done till 6% taper was reached. Specimens were then separated into four subgroups, and the final obturation procedure was performed for all specimens in groups A1 and B1 and A2 and B1 and B2, respectively. Paper points were used to dry the root canals after irrigating them with 3% sodium hypochlorite, neutralized with sodium thiosulfate solution, before saline was administered and paper towels were used to remove any remaining water. As a sealant, both groups used[3] AH plus Dentsply.

A1, A2 and B1, B2 (n = 10) were formed by cutting the file 3 mm from the tip with a round diamond point in the canals. The apical third of subgroups A3, A4, and B3, B4 (n = 5) had no different instruments.

SybronEndo (Europe) gutta-percha gauges (A1 and B1) were used to measure the tip diameters of the instruments in these two subgroups, and the same gauge was used to trim the same-sized point to achieve lateral condensation. Snug-fitting 25, 0.06 taper gutta-percha was used for obturation in subgroups A3 and B3 by using the lateral condensation technique.

Root canals in subgroups A2, A4, and B2, B4 were obturated using the Obtura II needle set at 15 mm. The entry was protected by the use of IRM (Dentsply). The obturated specimens were tested for their ability to seal using a dye extraction procedure.[4] Two coats of nail varnish were applied to the specimens, with the exception of a 3-mm zone surrounding the apical foramen. The apices were immersed in a 2% methylene blue solution (Spectrum, Cochin, India) for 24 h at 37°C and normal atmospheric pressure. The roots were then cleaned with tap water for 30 min, and the nail polish was removed using polishing discs. Nitric acid was used for 6 days to extract the roots, which were then mixed with 6 days' worth of alcohol to produce the final product, which was then stored in the refrigerator (Spectrum, Cochin, India). We used distilled water to dilute the acid from the specimens to a concentration of 0.15 mL, and the distilled water was diluted to a concentration of 1.35 mL. Genta-percha particles were removed from the dye by centrifugation at 14,000 rpm for 3 min. Next, 1 mL of supernatant was taken from each test tube and put in a cuvette. A spectrophotometer (Spectrophotometer-106, Systronic Ahmedabad, India) was used to measure the absorbance at 590 nm by using a 10-fold diluted nitric acid as the blank.

Statistical analysis

This study utilized descriptive statistical analysis. Categorical measures yielded mean ± SD (min–max) findings, while continuous measurements provided the results in mean ± SD (min–max) (percent). The significance level was 5%. Study parameters were analyzed by performing an ANOVA test to determine whether or with how much significance the parameters varied between groups. For this test, an ANOVA test was employed. On a metric scale, two groups were analyzed to find the significance of study parameters by using a Student t test (two-tailed, independent). To measure the homogeneity of variance, Leven's test was applied.

The analysis of the data was completed using the software called SAS 9.2, SPSS 15.0, Stata 10.1, MedCalc 9.0.1, Systat 12.0, and R version 2.11.1. These products are supported by Microsoft Word and Excel.

RESULTS

Group A1 had a substantially lower leakage rate than group B1. Research indicated that there was no statistically significant difference between the two groups A2 and B2. Group A4 leaked much less than group B4 [Table 1].

Table 1

Percentage of absorption

Subgroups	Group A	Group B	Mean Difference
1	0.023+0.081	0.031+0.081	0.008*
2	0.010+0.002	0.013+0.081	0.005*
3	0.022+0.003	0.023+0.081	0.003*
4	0.003+0.005	0.002+0.081	0.002*

RACE and K3 system specimens had a substantially bigger leakage volume when they were isolated from one other than when they weren't Regardless of the presence or absence of separated instruments, A2, A4 and B2, B4 were substantially less leaky than the lateral condensation technique (A1, A3 and B1, B3), as shown in Tables 2 and 3.

Table 2

Pairwise group comparison as per post-hoc Tukey test in specimens prepared using RACE system

Percentage of adsorbance	Mean difference	P
Group A1-A3	0.02	<0.01*
Group A1-A4	0.03	<0.01*
Group A1-controls	0.01	<0.01*
Group A2-A3	0.00	0.4
Group A2-A4	0.03	0.0*
Group A2-controls	0.00	0.9
Group A3-A4	0.02	0.07*

*Statistically significant with a p value less than 0.05

Table 3

Pair-wise group comparison as per post-hoc Tukey test in specimens prepared using K3 system

Percentage of adsorbance	Mean difference	P
Group B1-B3	0.03	<0.01*
Group B1-B4	0.04	<0.01*
Group B1-controls	0.02	<0.01*
Group B2-B3	0.00	0.6
Group B2-B4	0.01	0.0*
Group B2-controls	-0.01	0.7
Group B3-B4	0.04	0.3

DISCUSSION

Root canal sealing prevents microorganisms from re-entering the root canal system, limits germ re-entry and multiplication, confines pathogen remains inside the root canal system, and prevents microorganisms from re-entering the root canal system. It also protects the oral cavity and periapical region from bacterial penetration and byproducts that make their way into the root canals; otherwise, the endodontic treatment outcome could be jeopardized. As a result, root canal obturation must be evaluated as the final stage of root canal treatment. Two rotary systems—K3 and RACE—were selected for the present study, with differing file designs. In comparison to the K3 system, the RACE system has three radial lands and an overall constant diameter, but has an asymmetrical cross-section.

In the present investigation, RACE and K3 yielded different results when the specimens were produced without separating fragments, but when the experiments were done with separating fragments, RACE and K3 achieved the same results. This may be because various cross-sectional designs (RACE and K3) were used on the instrument. NiTi instruments with active cutting blades have been demonstrated to have better canal cleanliness than those with radial lands in studies.[56] Additionally, the container could be in the way of materials that are meant to fill the canal, thus causing the construction of a good seal to be compromised. It is possible that RACE exhibited increased leakage because of this. Although RACE was shown to be more effective than K3 in terms of overall cleanliness, there was no statistically significant difference when it came to cleaning the smear layer in the apical third of the root canal.[7]

A typical endodontic obturation technique is the cold lateral condensation of gutta-percha. Due to cavities, spreader tracts, and incomplete gutta-percha cone and root canal fusing, it has been questioned whether it is possible to reproduce the interior surface of a root canal.[8] Research has shown that a root canal sealer is still needed, despite the increased adaption of thermoplasticized gutta percha to the dentine of root canals.[9]

When shattered bone fragments with lateral condensation were obturated with Obtura II in this investigation, there was more leakage than when fragments were separated and OBTURA II was utilized to obturate the canal wall apically. There is a possibility that OBTURA II helps in maintaining a better seal by penetrating between the fractured pieces and the canal wall.

No statistical association was found between the Obtura II and lateral condensation approaches in a study by Rahimi et al.;[10] however, Tsukada et al.[11] found that the Obtura II method's utilization of gutta-percha was unsatisfactory when it was compared to the other method. The method employed, like Obtura II's thermoplastic root canal filling technology, is technique-dependent, which might lead to variation in outcomes.[12]

Root canal filling materials and obturation procedures have been tested using dye penetration,[13] electrochemical leakage tests,[14] dye extraction,[4] bacterial leakage,[15] and salivary leakage.[16]

There were some differences in how Camps and Pashley's study was conducted; however, when it came to how they measured fluids passing through the interface between root and the obturating materials in terms of dye extraction and fluid filtering,[4] this did not explain why one method worked better than the other. The fluid filtering method has the following qualities: over time, values decrease as the water penetrates all abnormalities.[13] That is why in the current investigation, the dye extraction method was utilized.

CONCLUSION

Independent K3 instrument groups were observed to leak more often than separate RACE systems in this investigation. Less leakage was seen with the Obtura II than the lateral condensation process. It should be done with caution, however, as it is only one of the many things that could alter the outcome of treatment when files are separated.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.