The relative sealing ability of paste-type filling materials

Filling ability of three variants of the single-cone technique with bioceramic sealer: a micro-computed tomography study

The present study evaluated the quality of single-cone root canal fillings with bioceramic (BC) sealer using three different techniques by means of micro-computed tomography (micro-CT). The canals of 30 extracted single-rooted permanent teeth were shaped with R40 Reciproc blue files and filled with the single-cone technique (SCT). BioRoot RCS BC sealer was placed inside the canals with one of the following master cones: R40 cone to working length (RWL, n = 10); R40 cone trimmed 1 mm short of working length (RWL-1, n = 10); non-standardized gutta-percha cone to working length (NSWL, n = 10). A quantitative and qualitative micro-CT analysis assessed the filling quality and internal/external voids formation. Collected data underwent statistical analysis by multivariate one-way analysis of variance (α = 0.05). In all groups, the voids were minimal and prevalently external. The NSWL and RWL-1 groups had increased sealer ratios in the whole canal and the apical canal portion, respectively. The lowest amounts of voids were found in the RWL group; the void volumes were slightly greater in the RWL-1 mm and NSWL groups, especially at the apical level. Two alternative SCTs showed satisfactory filling ability, uniform distribution of the BC sealer, and a minimally increased voids formation compared to the standard SCT with dedicated cone. The two tested alternative SCTs could take advantage of the beneficial characteristics of the BC sealer, which evenly filled the endodontic space, ideally sealing both the major and the accessory communications with the periodontium.

A Comparative Study of the Quality of Apical Seal in Resilon/Epiphany SE Following Intra canal Irrigation With 17% EDTA, 10% Citric Acid, And MTAD as Final Irrigants - A Dye Leakage Study Under Vacuum

INTRODUCTION

Adequate apical sealing ability of the root canal filling material is an essential requisite for a successful endodontic therapy. Various endodontic irrigants are used for the removal of smear layer before obturating with a solid core material, thereby, reducing microleakage and improving apical seal. Resilon, a synthetic material was developed as an alternative to replace the conventional gutta-percha (standard root canal filling material) and traditional sealers for the obturation of endodontically treated teeth.

AIM

To evaluate and compare in-vitro, the post obturation apical seal obtained with Resilon /Epiphany SE (Self Etch) sealer following irrigation with 17% Ethylenediamine Tetra-Acetic Acid (EDTA), 10% citric acid, and MTAD (a mixture of doxycycline, citric acid, and a detergent, Tween 80), as final irrigants in combination with Sodium hypochlorite (NaOCl) using dye leakage under vacuum method.

MATERIALS AND METHODS

Fifty five single rooted human maxillary central incisors were subjected to root canal instrumentation. Based on the final irrigation solution, samples were divided into three experimental groups (n=15); (I) 17% EDTA + 1.3% NaOCl, (II) 10% citric acid + 1.3% NaOCl, (III) MTAD + 1.3% NaOCl and two control groups (positive and negative) with 0.9% normal saline as a final irrigant. The samples were obturated with resilon/epiphany SE sealer according to manufacturer instructions and placed in 2% rhodamine B dye solution under vacuum pressure for 30 minutes and allowed to remain in the dye for seven days. All samples were then longitudinally split and examined for dye leakage under stereomicroscope and the data were statistically analysed using one-way ANOVA and post hoc tukey test.

RESULTS

Statistically significant difference (p=0.001) was observed in the mean apical leakage between the experimental and the control groups. However, there was no significant difference (p>0.05) observed in the mean apical leakage amongst the three experimental groups.

CONCLUSION

17% EDTA, 10% citric acid, and MTAD were equally effective in achieving the post-obturation apical seal with resilon/epiphany SE sealer when used as a final irrigant in combination with NaOCl.

Gas permeability: a new quantitative method to assess endodontic leakage

AIM

The aim of this study was to evaluate a new endodontic leakage measurement method.

MATERIALS AND METHODS

Permeability was assessed measuring the gas flow passing through the root. Positive and negative tests were carried out to assess the validity of the method. We used glass capillaries for calibration (diameters of 15, 30, 40, 50 and 75 microm). The applicability of the method was assessed with human teeth using three sealing methods: GuttaFlow (GF) and a single cone; Pulp Canal Sealer (PCS) and a single cone; PCS and system B.

RESULTS

This method demonstrated to be highly reproducible as the standard deviation was approximately 1% on average with glass capillaries. Significantly higher leakage (p<0.05) was recorded for endodontic treatment with GF and single cone compared to PCS and single cone and PCS with system B.

CONCLUSION

Gas permeability is quantitative, sensitive, non-destructive and reproducible and seems appropriate for endodontic tests. It would participate in the indirect comprehension of leakage phenomena.

Influence of reduced air pressure methods on dye penetration in standardized voids

OBJECTIVE

The objective of this study was to evaluate the influence of the moment when reduced pressure is applied on dye penetration patterns.

STUDY DESIGN

Nine hundred and sixty glass capillary tubes of different inner diameter (0.3 mm and 0.8 mm), divided into 48 groups, were submerged into dye in 3 different positions (horizontally, opening upwards, and opening downwards) under different vacuum conditions (passive, 5 kPa, 35 kPa, 70 kPa reduced pressure). When reduced pressure was applied half of the groups were submerged into dye before and half of the groups after the application of reduced pressure. Linear dye penetration was measured. Univariate analysis was performed with Mann-Whitney U test and Kruskal-Wallis test to select variables to be included in the regression model. A multiple logistic regression analysis with backward elimination was performed to assess the influence of different covariates on linear dye penetration.

RESULTS

The multivariate linear regression showed that the moment of vacuuming had the greatest positive effect on linear dye penetration value (beta = 10.6, P < .0001). Also the level of pressure reduction had a positive effect on the outcome variable (beta = 0.2, P < .0001) while the vertical positioning of the tubes has negatively affected the outcome variable both for the open end upside (beta = -1.01, P = .024) and the open end downside (beta = -1.05, P = .019). Diameter of the tubes (P = .442) and immersion time (P = .727) had no effect on the outcome of linear dye penetration.

CONCLUSIONS

Even minimum air pressure reduction applied before immersion of the specimens allowed the dye to extensively penetrate the voids.

A comparison of techniques for assessment of coronal dye leakage

This study was designed to compare different techniques for coronal dye leakage testing. One hundred and fifty extracted human anterior teeth were fully instrumented and randomly divided into two experimental groups of 60 teeth each, plus two groups of 15 teeth each for positive and negative controls. One group was rinsed with 5.25% NaOCl (smear layer intact), whereas the other group was flushed with 17% EDTA and 5.25% NaOCl (smear layer removed). Roots were obturated with gutta-percha using lateral condensation and AH Plus as root canal sealer. Each experimental group was divided into three subgroups of 20 teeth each for three methods of testing coronal dye leakage: passive dye penetration, penetration with vacuum applied, and fluid filtration methods. The teeth were left in 100% humidity at 37 degrees C for 5 days before being immersed in Indian ink for 2 days and cleared. The linear extent of dye penetration was measured. Mean depth of leakage for the groups with the smear layer intact was 2.5 +/- 1.0 mm for passive dye penetration, 6.7 +/- 2.8 mm for vacuum dye penetration, and 3.0 +/- 1.1 mm for fluid filtration dye penetration. In the group in which the smear layer was removed, the mean depths of leakage were: 3.2 +/- 2.1 mm for passive dye penetration, 5.8 +/- 2.8 mm for vacuum dye penetration, and 3.4 +/- 2.1 mm for fluid filtration. The vacuum method resulted in significantly (p < 0.05) more dye penetration than fluid filtration and passive dye penetration. The presence or absence of smear layer had no statistically significant effect (p > 0.05) on any of the leakage testing techniques.

Area-metric analysis of dye leakage for evaluation of sealing ability of root canal obturation techniques

Root canal sealing ability of obturation techniques has been assessed in vitro with various methods. The majority of the methods employ microleakage tracers and particularly dyes. In vitro measurements of dye penetration are either linear or volumetric. Area-metric analysis is a three dimensional registration method of dye leakage. The purpose of the present study was to evaluate in cleared teeth area-metric analysis as opposed to linear analysis of dye penetration. Forty freshly extracted single rooted human teeth were used. Instrumentation was carried out using Hedstroem files with a step back technique. The root canals were obturated using Roth sealer and qutta-percha cones and lateral condensation technique. The roots were then subjected to dye leakage tests under vacuum of 50 mmHg for 20 min. India ink was used as the tracer. The roots were randomly divided in two groups. In Group A the roots were cleared and linear measurements of the dye penetration were recorded The roots in Group B were ground stepwise transversally and subjected to area metric analysis. The results showed that area-metric analysis enabled sufficient recordings of the dye leakage patterns and the volume of the dye penetration could also be calculated.

Effect of reduced air pressure on dye penetration in standardized voids

OBJECTIVE

This study determined the correlation between the degree of dye penetration in standardized voids to various reduced pressures.

STUDY DESIGN

Standardized voids of 0.50 and 0.22 mm in diameter were created in 60 human roots; specimens were divided into five groups. Four groups were subjected to a 2% filtered aqueous methylene blue dye solution under different conditions of atmospheric pressure for 7 days and reduced pressures of a 10 torr, a 260 torr, and a 510 torr for 30 minutes. The conditions for the fifth group were similar to the last group except that ethyl alcohol was substituted for water in the dye.

RESULTS

All positive control specimens showed complete dye penetration. The least linear dye penetration was observed in passively immersed specimens. The results were significantly different from those when reduced pressure had been used (p < 0.001). There were no significant differences among the groups with reduced pressure. No significant difference was found at any pressure level between the means of dye diffusion in the 0.50 and the 0.22 mm voids. The smallest standard deviations were observed for the most reduced air pressure of 10 torr, followed by the group of the least reduced pressure of 510 torr, with the use of the tincture dye solution.

CONCLUSIONS

A 10-torr reduced pressure and an application of the tincture dye solution would provide an improved method for microleakage studies.

Effects of vacuuming on dye penetration patterns in root canals and glass tubes

This study compared the dye leakage pattern of prepared root canals with that of glass tubes, with and without vacuuming. The apical 12 mm of 40 calcified root canals were prepared to tubes with a diameter of 0.5 mm. The coronal end of these canals and 40 glass tubes with similar diameters (12 mm x 0.5 mm) were closed with 2 mm of Cavit. Twenty samples from each group were left empty, and the rest (20) were filled with gutta-percha without sealer. Half of the samples of filled (10) and unfilled (10) specimens were then placed horizontally in 2% methylene blue dye. The other half (10) of the samples from each group were placed in a vacuum (25 mm Hg) and submerged in the dye. Leakage was then measured in millimeters and statistically analyzed using analysis of variance. The 20 empty glass tubes with or without vacuum leaked 17% or less of their lengths. The 20 glass tubes filled with gutta-percha averaged 70.5% leakage. Of those, the 10 glass tubes that were vacuumed had 100% leakage. Empty root canals exhibited mean leakage of 74% without vacuum and 91% of their length with vacuum. Canals filled with gutta-percha leaked a mean of 95.5% of their entire lengths without vacuum and 100% with vacuum (no significant difference). The results showed that filled and unfilled, prepared root canals leaked significantly more than their glass tube counterparts (p < 0.001), and vacuuming may not be necessary for dye leakage studies in filled root canals.

Comparison of apical leakage in root canals obturated with various gutta percha techniques using a dye vacuum tracing method

In this study, residual apical microlumina remaining after obturation with five different gutta-percha obturation methods were traced with an efficient vacuum method. Seventy-nine human maxillary anterior teeth were instrumented and divided into five groups. The groups were obturated with single-cone techniques, lateral condensation, vertical condensation, Thermafil, and Ultrafil techniques. All specimens were immersed in a vacuum flask containing 2% methylene blue dye solution. The air was evacuated with a vacuum pump to an absolute pressure of 75 torr for 30 min. The roots were sectioned longitudinally and the linear extent of dye penetration was measured. Group mean linear dye penetration values were: single-cone technique, 1.55 +/- 0.95 mm; lateral condensation, 2.25 +/- 1.46 mm; vertical condensation, 2.61 +/- 2.61 mm; Thermafil 1.41 +/- 1.16 mm; and Ultrafil 3.51 +/- 4.70 mm. There were no statistically significant differences between the gutta-percha obturation methods. The clinical implications of these findings are discussed.

Dimensional changes of endodontic sealers

The purpose of this study was a long-term comparison of the dimensional changes of endodontic sealers of diverse properties. The sealers were injected as thin layers on the internal walls of glass pipettes 1 mm in diameter. The pipettes were filled with deionized water, and the water meniscus levels were recorded periodically up to 180 days. The water was removed from the pipettes, samples were allowed to dry, and the mass and the volume of the sealers were measured. AH26 and Endo-Fill had an initial expansion followed by a volumetric loss. The two zinc oxide eugenol-based sealers studied started to shrink within hours after mixing; the first volumetric loss for AH26 was recorded during the first 30 days and for Endo-Fill after 30 days. The least dimensional change at any time was observed for Endo-Fill. It was concluded that a significant dimensional change and continued volume loss can occur in some endodontic sealers.

An evaluation of the effect of methylene blue dye pH on apical leakage

The effect of varying the pH of 2% methylene blue dye on apical leakage was evaluated. Eighty-four roots of extracted human teeth were used in this study. The roots were endodontically cleaned and shaped, obturated, apically resected, and amalgam or Temporary Endodontic Restorative Material retro-fillings were placed. The roots were immersed for 7 days in dye solutions of controlled pH of 1, 2, 3, 5 or 7, or in a 2% unbuffered deionized water solution of methylene blue. The results demonstrated significantly less leakage in the pH 1 and 2 amalgam groups. All other amalgam groups and the Temporary Endodontic Restorative Material groups showed no significant differences attributable to pH. Temporary Endodontic Restorative Material retrofilling groups demonstrated statistically significantly less apical leakage at each pH evaluated than the amalgam-retrofilled groups. Additionally, a significant buffering effect of the root structure on the dye solutions was measured.

Leakage evaluation with and without vacuum of two gutta-percha fill techniques

Two sets of 30 roots were obturated either with lateral condensation or a halothane dip technique. Fifteen roots from each group were immersed in India ink with vacuum and 15 without vacuum. Each root was coated with nail polish and wax, leaving only its apical end open for ink penetration. The roots were cleared and three linear measurements were made: distance of ink penetration coronal to the gutta-percha apical tip; distance from the gutta-percha tip to major foramen; and distance from the major foramen to anatomical apex. The average length of ink penetration coronal to the apical extension of the gutta-percha for the lateral condensation groups combined was 1.33 mm and for the halothane groups combined was 2.15 mm. There was no significant difference between vacuumed and not vacuumed for degree of ink penetration. The gutta-percha of the halothane-dipped groups advanced significantly closer to the foramen than the lateral condensation groups (0.38 mm versus 0.65 mm).

Factors affecting apical leakage assessment

This study was conducted to evaluate the influence of immediate versus delayed immersion time, and passive dye immersion versus centrifuged dye on apical leakage measurements. Eighty-four extracted human teeth with single straight canals were instrumented and divided into four experimental groups of 20 teeth each plus 2 negative and 2 positive controls. Low-temperature injection thermoplasticized gutta-percha and sealer were used to obturate the root canals. In groups A and B the filling materials were allowed to set for 72 h before the teeth were placed in India ink. In groups C and D the teeth were placed in India ink immediately after obturation. Also, in groups B and D the teeth were centrifuged in India ink for 20 min at 3,000 rpm before being immersed in ink. After 72 h in India ink, the teeth were cleared, and the linear extent of ink penetration was measured with a stereomicroscope. Statistical analysis of the data revealed no significant difference in leakage among the experimental groups whether the teeth were immersed in ink immediately after obturation or after setting of the filling materials for 72 h, and whether or not the teeth were centrifuged in ink prior to immersion.

A comparison of leakage of filling materials in demineralized and non-demineralized resected root ends under vacuum and non-vacuum conditions

A study was conducted to compare the marginal apical leakage of root-end filling materials under vacuum and non-vacuum conditions, and to assess the effect of demineralization by application of citric acid to the root ends on the apical marginal leakage of root end filling materials. The root canals of 148 extracted human canines and premolars were handfiled and sealed with gutta-percha and Roth's 801 sealer using cold lateral condensation. The teeth were divided into 8 groups that received retrofilling materials. The materials tested were amalgam, IRM and gutta-percha/sealer with and without successive application of citric acid. Half of the specimens were placed under vacuum conditions in methylene blue dye, and the other half were placed in the dye for the same time period without exhausting air from the flask. The teeth were split longitudinally and the extent of dye penetration was determined with a stereomicroscope and eyepiece micrometer. The most evident difference in dye penetration was found between the positive control groups. Under vacuum conditions, the positive controls showed complete penetration of the unobturated canal system with dye. With passive immersion only partial penetration of the unobturated canal system occurred. Application of citric acid to the root end did not adversely affect the seal of amalgam, IRM or gutta-percha/sealer.

Human saliva coronal microleakage in obturated root canals: an in vitro study

This study assessed salivary penetration through obturated root canals as related to time by using two methods of analysis--histological examination and dye penetrations. A total of 160 human maxillary anterior teeth were instrumented to size 60 Hedstrom file. Ten of the teeth were not obturated; 150 teeth were obturated by lateral condensation of gutta-percha and Roth's root canal sealer. Fifty of these teeth received intermediate restorative material temporaries to a thickness of approximately 3 mm. All teeth were immersed in 50 ml of whole human saliva and kept at 37 degrees C and 100% humidity. The saliva was changed daily. At 2, 7, 14, 28, and 90 days, 32 teeth were removed from the saliva. Of these, two were unobturated and were examined for bacterial penetration by culturing of the apical one-third. Ten teeth without temporaries were immersed in Pelikan ink for 2 days to demonstrate the extent of salivary penetration. These teeth were decalcified and cleared to allow direct measurement of dye penetration. Decalcified serial 7-microns-thick sections were prepared from the remaining 20 teeth, 10 with and 10 without intermediate restorative material temporaries. The sections were stained with hematoxylin and eosin stain and Brown and Hopps stain. Saliva penetration assessed in histological sections was significantly less than was visualized with dye analysis. Salivary penetration at 3 months was significantly greater than at the four earlier study periods. This amount of salivary penetration was considered to be clinically significant. The results strongly suggest retreatment of obturated root canals that have been exposed to the oral cavity for at least 3 months.

Entrapped air and its effects on dye penetration of voids

This study was conducted to determine the effect of entrapped air on the ability of methylene blue dye to penetrate known and measurable voids. Thirty six capillary tubes were sealed at one end and had standardized voids created within the lumen. Three equal groups of 12 test specimens and 4 controls were subjected to dye penetration by the methods of passive immersion for 7 days, centrifuging at 3,000 rpm for 5 minutes and immersion in a vacuum of 26 mm of mercury for 5 minutes. Measurement of linear dye penetration was made by removing shavings from the sealed end until dye could be observed. Negative controls showed no dye penetration and positive controls showed complete penetration. The vacuum method showed 100% penetration in all cases, while centrifuging had a mean of 91.7 /+ 8.7% penetration and passive immersion had a mean of 20.7 +/- 5.4% penetration. This study demonstrates that passive dye leakage studies are unreliable and very variable. The vacuum method whereby all entrapped air is removed is the most reliable method for dye penetration studies.

Silver glass ionomer cement as a retrograde filling material: a study in vitro

Comparison was made of the apical microleakage of retrograde fillings with amalgam and with silver glass ionomer cements using a modified dye penetration method. Forty instrumented human teeth were divided into four groups. Each group was characterized by a different retrograde filling material or technique: Group 1--silver glass ionomer (SGI); group 2--SGI with previous acid wash of the cavity; group 3--SGI in a previously acid washed cavity, protected with varnish; and group 4--zinc-free amalgam. A paper cone for dye adsorption analysis was placed in contact with retrofill and the main canal was obturated with thermoplasticized gutta-percha. All teeth were coated, immersed in methylene blue dye, and evacuated to assure complete penetration of the dye in any possible void. Later the teeth were cleared and evaluated under stereomicroscope. Statistical analysis showed that group 1 had the least microleakage of all. In addition, the biocompatibility of the SGI and varnish was compared with that of amalgam using the 51Cr release evaluation method. The results showed that SGI and varnish were less cytotoxic than amalgam. It was concluded that SGI cement can be considered an alternative retrograde filling material.

Comparison of the sealing ability of four obturation techniques

This study compared the apical seal produced by four obturation techniques. The Canal Finder system was compared with lateral condensation, the Ultrafil system, and the sectional warm gutta-percha techniques. Forty-two anterior single-rooted teeth were instrumented. Ten teeth were not obturated and served as positive and negative controls. The apical seal was tested for leakage with 0.25% methylene blue dye. The teeth were shaved horizontally and dye penetration was measured with a Boley gauge. Results revealed there was no statistically significant difference among the four obturation techniques.

Influence of entrapped air on the accuracy of leakage studies using dye penetration methods

Entrapped air can inhibit dye penetration resulting in failure to demonstrate existing voids. A new approach to study dye penetration was developed in which the entrapped air was evacuated before the dye was introduced. This method was compared with the regular technique of passive dye diffusion. Uniformly prepared root canal specimens were filled with AH26. Two different sizes of standardized voids were created in the specimens. Specimens were either immersed passively in 2% methylene blue for a week or placed in a chamber with 100 mtorr absolute pressure, after which the dye was introduced while the vacuum was maintained. Leakage was measured stereomicroscopically. Controls with no voids showed insignificant external leakage. Passive dye penetration resulted in incomplete filling of the voids regardless of size of the voids, whereas vacuum dye delivery resulted in complete filling of the voids. Results of this study suggest that entrapped air produces artifacts in passive immersion technique; therefore, the sample should be evacuated prior to the dye introduction in order to demonstrate the full extent of void in future dye penetration studies.

The usefulness of dye-penetration studies reexamined

An in vitro study to determine the usefulness of dye-penetration studies was conducted. In part I, teeth were prepared through the foramen and then left open, either apically, coronally, or at both ends. In all cases, the dye did not penetrate the full length of the canal. The only exception was when both ends were left open and the teeth were placed into the dye in an upright position. In part II, a measurable defect in a canal filling the length of the canal was created and left open apically. When the tooth was immersed in dye, the penetration was incomplete. When the air was removed by vacuum pump prior to placement in the dye, the penetration was total. The validity of dye studies that do not consider entrapped air is open to question.