A Comparative Evaluation of Five Obturation Techniques in the Management of Simulated Internal Resorptive Cavities: An Ex Vivo Study.

BACKGROUND: Root resorption is the loss of dental hard tissues as a result of clastic activities. It might be broadly classified into external or internal resorption by the location of the resorption in relation to the root surface. the various techniques used these days for filling internal resorption include warm condensation, vertical condensation, core techniques, thermoplasticized gutta-percha, warm vertical compaction, and cold lateral condensation.
OBJECTIVES: The aims and objectives of this study were to compare the quality of root fillings in artificially created internal resorption cavities filled with warm vertical compaction, lateral condensation, Obtura II along with System B, E and Q plus along with System B, and Thermafil, and to calculate the percentage of gutta-percha, sealer, and voids using an ImageJ software.
RESULTS: Results between the warm vertical compaction (group I), lateral condensation (group II), Obtura II with System B (group III), E and Q plus with System B (group IV), and Thermafil (group V), group III showed the highest percentage of gutta-percha plus sealer and gutta-percha, and least number of voids, which was statistically significant (P < 0.000).
CONCLUSION: It can be concluded that Obtura II along with System B was found to be the most suitable obturation technique for the management of teeth exhibiting internal resorption. Thermafil was found to give the poorest obturation quality when used to fill the teeth with internal resorption. Similarly, lateral condensation technique was observed to show maximum sealer and hence was not ideal for the management of internal resorptive cavities.

INTRODUCTION

Asuccessful root canal therapy, more often than not, depends upon complete obliteration of root canal space by a dimensionally stable and biologically compatible material.[1] Complete filling of the root canal space with an inert filling material is often considered as one of the vital goals of root canal treatment.[2]

Root resorption is the loss of dental hard tissues as a result of clastic activities. It might be broadly classified into external or internal resorption by the location of the resorption in relation to the root surface. Internal root resorption presents as an irregular defect in the root canal, making that area inaccessible to normal method of cleaning and shaping as well as obturation.[3] Clinically, internal root resorption is usually asymptomatic and diagnosed through routine radiographs or by the sign of a “pink spot” on the crown. Radiographically, internal root resorption appears as a fairly uniform, radiolucent enlargement of the pulp canal and distortion of the original root canal outline.[4] The complete extent of the defect cannot be determined either clinically or radiographically, which further calls for finding a perfect way of obturating these defects.[1] It is generally accepted that root fillings should contain more gutta-percha and less sealer. This may be more important when filling root canals with resorptive lacunae. In resorptive lacunae, it is difficult to remove all bacteria and their products from the dentinal tubules. Dense compacted gutta-percha may block dentinal tubules, and this may lead to better entombment of microorganisms.[2]

According to Gencoglu et al.,[2] the various techniques used these days for filling internal resorption include warm condensation (MicroSeal),vertical condensation (System B), core techniques (Thermafil, Soft Core, JS Quick-Fill), thermoplasticized gutta-percha (E and Q plus, Obtura), warm vertical compaction, and cold lateral condensation. The aims and objectives of this study were to compare the quality of root fillings in artificially created internal resorption cavities filled with warm vertical compaction, lateral condensation, Obtura II along with System B, E and Q plus along with System B, and Thermafil, and to calculate the percentage of gutta-percha, sealer, and voids using an ImageJ software.

MATERIALS AND METHODS

Thirty-five freshly extracted human intact maxillary central incisor teeth with fully formed root apices were taken. In this study, the selection criteria were teeth with no calcification, no internal resorption, and no previous root canal filling. The collected teeth were almost of 21-mm length and were ultrasonically cleaned for removing calculus and debris and stored in saline. A conventional endodontic access was prepared in each tooth and a size 10 K-file was inserted to determine the location of the apical foramen. The teeth were instrumented to master apical file size 40 and the step-back technique till size 80 and then irrigated with saline and 2.5% sodium hypochlorite solution.

To create artificial internal resorptive cavities, the roots were sectioned horizontally 7 mm from the apex with a fine diamond disk [Figure 1]. Semicircular cavities of 2 mm were created using a low-speed no. 6 round bur around the periphery of the root canal opening of each section. Then the sections were repositioned together using feviquik glue on the dentine surface around the cavities. Care was taken to maintain the patency of the canal by using minimal amount of glue and a master apical cone of 40 size was placed to prevent the glue from flowing into the resorptive cavity. Then radiographs were taken in both buccolingual and mesiodistal view. Each tooth was embedded in rubber-based impression material. Then, 35 teeth were randomly assigned to five groups of seven samples each. Group 1:Warm vertical compaction [Figure 2]; group 2: lateral condensation [Figure 3]; group 3: Obtura II (Obtura corporation, Fenton, MO) with System B (Analytical Technology, Orange, CA) [Figure 4]; group 4: E and Q plus (Meta Dental Corp) with system B [Figure 5]; and group 5 with Thermafil (Thermaprep plus) [Figure 6]. After obturation, coronal access was sealed with type 2 glass ionomer cement. Following filling, the teeth were stored for 7 days at room temperature to ensure all materials had set. The teeth were removed from rubber-based impression material and radiographs of the teeth were taken in both buccolingual and mesiodistal view. Then, each tooth was sectioned with a rotary saw 7 mm from the apex at the level of the previous cut and under cold water to minimize gutta-percha smearing. Photographs of both surfaces of the sectioned area were taken using a Nikon (Tokyo, Japan) Coolpix 885 digital camera, which was mounted on a stereomicroscope ocular eye at ×16 magnification.

Figure 1

Radiograph revealing resorptive cavity in buccolingual and mesiodistal view

Figure 2

Warm vertical compaction (Group I)

Figure 3

Lateral condensation (Group II)

Figure 4

Obtura II along with System B (Group III)

Figure 5

E and Q along with System B (Group IV)

Figure 6

Thermafil (Group V)

The photographs were transferred to a computer and an image analysis program (ImageJ software) was used to calculate the percentage of gutta-percha, sealer, and voids. ImageJ is a java image processing and analysis program that can calculate area and pixel value statistics of user-defined selections. It can measure distances and angles. It can create density histograms and line profile plots. It supports standard image processing functions such as contrast manipulation, sharpening, smoothing, edge detection, and median filtering. It does geometric transformations such as scaling, rotation, and flips. Image can be zoomed up to 32:1 and down to 1:32. All analysis and processing functions are available at any magnification factor. The program supports any number of windows (images) simultaneously.

The results of this study were subjected to statistical analysis to interpret the mean, standard deviation, and mean difference. One-way analysis of variance (ANOVA) and post hoc Tukey test were used for statistical analysis. One-way ANOVA was used to study the overall variance within groups. Post hoc Tukey test was conducted to determine which groups differ from each other.

RESULTS

Results show the stereomicroscopic pictures of different obturation techniques showing gutta-percha, sealer, and voids.

Table 1 shows mean and standard deviation of the ratios of percentage of gutta-percha and sealer, gutta-percha, sealer, and voids. Between the warm vertical compaction (group I), lateral condensation (group II), Obtura II with System B (group III), E and Q plus with System B (group IV), and Thermafil (group V), group III showed the highest percentage of gutta-percha plus sealer and gutta-percha, and least number of voids, which was statistically significant (P < 0.000). Table 1 also shows the highest percentage of sealer in group II, which was statistically significant (P < 0.000). It also shows the highest percentage of voids in group V, which was statistically significant (P < 0.000).

Table 1

Estimated least square mean (mean%) and standard deviation of the ratios evaluated in stereomicroscope (percentage of gutta-percha and sealer, gutta-percha, sealer, and void) between five groups

	Gutta-percha plus sealer	Gutta-percha	Sealer	Void
Warm vertical compaction (Group I)	92.67 ± 1.14	53.49 ± 1.73	39.22 ± 0.8191	7.28 ± 1.15
Lateral condensation (Group II)	90.19 ± 1.87	43.48 ± 0.872	46.64 ± 1.47	9.78 ± 1.85
Obtura II with System B (Group III)	96.12 ± 0.886	62.99 ± 0.927	33.16 ± 0.715	3.77 ± 0.826
E and Q plus with System B (Group IV)	94.63 ± 1.46	59.15 ± 1.59	35.47 ± 1.79	5.27 ± 1.42
Thermafil (Group V)	75.38 ± 1.63	35.01 ± 0.943	40.35 ± 1.44	24.59 ± 1.63

The mean difference is significant at the 0.000 level

Table 2 shows the ratios of mean difference and significance of gutta-percha and sealer (multiple comparison) within the groups. The mean difference is significant at the 0.05 level.

Table 2

Estimated ratios of mean difference and significance evaluated in stereomicroscope (percentage of gutta-percha and sealer) between five groups

Multiple comparison
Post hoc test
ependent variable: Gutta percha plus sealer
Gutta-percha plus sealer			Mean difference	Significance
Warm vertical compaction (I)	vs	Lateral condensation (II)	2.467*	0.000
		Obtura II with System B (III)	−3.462*	0.000
		E and Q with System B (IV)	−1.965*	0.005
		Thermafil (V)	17.285*	0.000
Lateral condensation (II)	vs	Warm vertical compaction (I)	−2.467*	0.000
		Obtura II with System B (III)	−5.930*	0.000
		E and Q with System B (IV)	−4.432*	0.000
		Thermafil (V)	−14.817*	0.000
Obtura II with System B (III)	vs	Warm vertical compaction (I)	3.462*	0.000
		Lateral condensation (II)	5.930*	0.000
		E and Q and System B (IV)	1.497	0.058
		Thermafil (V)	20.747*	0.000
E and Q plus with System B (IV)	vs	Warm vertical compaction (I)	1.965*	0.000
		Lateral condensation (II)	4.432*	0.000
		Obtura II with System B (III)	−1.497	0.058
		Thermafil (V)	19.250*	0.000
Thermafil (V)	vs	Warm vertical compaction (I)	−17.285*	0.000
		Lateral condensation (II)	−14.817*	0.000
		Obtura II with System B (III)	−20.747*	0.000
		E and Q with System B (IV)	−19.250*	0.000

*The mean difference is significant at the 0.05 level

Table 3 shows the ratios of mean difference and significance of gutta-percha (multiple comparisons) within the groups. The mean difference is significant at a P value of <0.05.

Table 3

Estimated ratios of mean difference and significance evaluated in stereomicroscope (percentage of gutta-percha) between five groups

Multiple comparison
Post hoc test
Dependent variable: Gutta percha
Gutta-percha			Mean difference	Significance
Warm vertical compaction (I)	vs	Lateral condensation (II)	10.013*	0.000
		Obtura II with System B (III)	−9.501*	0.000
		E and Q with System B (IV)	−5.654*	0.000
		Thermafil (V)	18.477*	0.000
Lateral condensation (II)	vs	Warm vertical compaction (I)	−10.013*	0.000
		Obtura II with System B (III)	−19.515*	0.000
		E and Q with System B (IV)	−15.667*	0.000
		Thermafil (V)	8.464*	0.000
Obtura II with System B (III)	vs	Warm vertical compaction (I)	9.501*	0.000
		Lateral condensation (II)	19.515*	0.000
		E and Q and System B (IV)	3.847*	0.000
		Thermafil (V)	27.979*	0.000
E and Q with System B (IV)	vs	Warm vertical compaction (I)	5.654*	0.000
		Lateral condensation (II)	15.667*	0.000
		Obtura II with System B (III)	−3.847*	0.000
		Thermafil (V)	27.132*	0.000
Thermafil (V)	vs	Warm vertical compaction (I)	−18.477*	0.000
		Lateral condensation (II)	−8.464*	0.000
		Obtura II with System B (III)	−27.979*	0.000
		E and Q with System B (IV)	−24.132*	0.000

*The mean difference is significant at the 0.05 level

Table 4 shows the ratios of mean difference and significance of sealer (multiple comparison) within the groups. The mean difference is significant at a P value of <0.05.

Table 4

Estimated ratios of mean difference and significance evaluated in stereomicroscope (percentage of sealer) between five groups

Multiple comparison
Post hoc test
Dependent variable: Sealer
Sealer			Mean difference	Significance
Warm vertical compaction (I)	vs	Lateral condensation (II)	−7.420*	0.000
		Obtura II with System B (III)	6.060*	0.000
		E and Q with System B (IV)	3.744*	0.000
		Thermafil (V)	−1.135	0.163
Lateral condensation (II)	vs	Warm vertical compaction (I)	7.420*	0.000
		Obtura II with System B (III)	13.480*	0.000
		E and Q with System B (IV)	11.165*	0.000
		Thermafil (V)	6.285*	0.000
Obtura II with System B (III)	vs	Warm vertical compaction (I)	−6.060*	0.000
		Lateral condensation (II)	−13.480*	0.000
		E and Q and System B (IV)	−2.315*	0.000
		Thermafil (V)	−7.195*	0.000
E and Q with System B (IV)	vs	Warm vertical compaction (I)	−3.744*	0.000
		Lateral condensation (II)	−11.165*	0.000
		Obtura II with System B (III)	2.315*	0.000
		Thermafil (V)	−4.880*	0.000
Thermafil (V)	vs	Warm vertical compaction (I)	1.135	0.163
		Lateral condensation (II)	−6.285*	0.000
		Obtura II with System B (III)	7.195*	0.000
		E and Q with System B (IV)	4.880*	0.000

*The mean difference is significant at the 0.05 level

Table 5 shows the ratios of mean difference and significance of voids (multiple comparison) within the groups. The mean difference is significant at a P value of <0.05.

Table 5

Estimated ratios of mean difference and significance evaluated in stereomicroscope (percentage of voids) between five groups

Multiple comparison
Post hoc test
Dependent variable: Voids
Voids			Mean difference	Significance
Warm vertical compaction (I)	vs	Lateral condensation (II)	−2.497*	0.000
		Obtura II with System B (III)	3.505*	0.000
		E and Q with System B (IV)	2.010*	0.004
		Thermafil (V)	−17.311*	0.000
Lateral condensation (II)	vs	Warm vertical compaction (I)	2.497*	0.000
		Obtura II with System B (III)	6.003*	0.000
		E and Q with System B (IV)	4.507*	0.000
		Thermafil (V)	−14.813*	0.000
Obtura II with System B (III)	vs	Warm vertical compaction (I)	−3.505*	0.000
		Lateral condensation (II)	−6.003*	0.000
		E and Q and System B (IV)	−1.495	0.054
		Thermafil (V)	−20.817*	0.000
E and Q with System B (IV)	vs	Warm vertical compaction (I)	−2.010*	0.004
		Lateral condensation (II)	−4.507*	0.000
		Obtura II with System B (III)	1.495	0.054
		Thermafil (V)	−19.321*	0.000
Thermafil (V)	vs	Warm vertical compaction (I)	17.311*	0.000
		Lateral condensation (II)	14.813*	0.000
		Obtura II with System B (III)	20.817*	0.000
		E and Q with System B (IV)	19.321*	0.000

*The mean difference is significant at the 0.05 level

DISCUSSION

In this study, maxillary central incisors with simulated internal resorptive cavities located in the middle third of the roots were used, because these are the teeth and areas in which internal resorption is most frequently seen.[5] In this study, AH plus sealer was used because it prevents movement and distortion of the gutta-percha during sectioning process. This was in accordance to the studies conducted by Goldberg et al.[5] and Gencoglu et al.[2] who also used AH plus sealer for obturation of internal resorptive cavities. The percentage of gutta-percha was highest in Obtura plus System B and this was similar to the studies by Stamos and Stamos[6] and Wilson and Barnes[7] who reported two cases of internal resorption in which the Obtura II system was used to successfully obturate the canals. Cathro and Love[8] concluded that System B plus Obtura II produced a homogenous obturation of gutta-percha with minimal sealer and no voids. The result for high percentage of gutta-percha was because it is a thermoplasticized technique in which regular beta phase of gutta-percha pellets is heated for obturation. The reason for lesser voids is that it involves placing of small aliquots of thermosoftened gutta-percha within the root canal and condensing them individually.[9] The higher percentage of gutta-percha found in E and Q plus and System B, which is very close to that observed with Obtura, can be supported by the fact that both have similar thermoplasticized and beta phase technique. The high sealer proportion in lateral condensation is associated with the inability of cold gutta-percha cones to be compacted into the cavities and the diffusion of the sealer into the resorption area during condensation.[2] More voids in the Thermafil technique may be because the warmed gutta-percha around the core material was not adequate in filling the hollow space in the resorptive area. In each core technique, the amount of gutta-percha surrounding the core material and the characteristics of fluidity is different and this may affect the filling quality of the core techniques in resorptive area.[2]

CONCLUSION

The success of treatment depends on the size of the resorptive lesion. If there is communication between the pulp and surrounding tissues, prognosis is less favorable. Even in situations where endodontic therapy could be successfully conducted, the ultimate outcome could nevertheless be a failure if the area of resorption is so large that too little tooth structure remains for the tooth to be able to withstand the normal strains and stresses associated with daily function.[10] Within the limitations of this study, it can be inferred that Obtura II along with System B was found to be the most suitable obturation technique for the management of teeth exhibiting internal resorption. Thermafil was found to give the poorest obturation quality when used to fill the teeth with internal resorption. Similarly, lateral condensation technique was observed to show maximum sealer and hence was not ideal for the management of internal resorptive cavities.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.