Comparison of the sealing ability of four obturation techniques

Sealing Ability and Adaptability of Nano Mineral Trioxide Aggregate as a Root-End Filling Material

Aim: Comparison between Nano MTA & MTA as a root-end filling materials regarding adaptability and sealing ability. Materials and Methods: Forty extracted human maxillary incisors with straight roots were used. After root canals preparation and obturation, the apical 3 mm of each root was resected perpendicular to the long axis of the tooth. Root end cavities were prepared to a depth of 3mm parallel to the long axis of the tooth. The teeth were randomly divided into two main equal groups of 20 samples each according to the root-end filling material used either MTA or Nano MTA. Ten samples from each group were sectioned longitudinally into two equal halves to measure the sealing ability and another ten samples from each group were sectioned transversally to obtain 1 mm thick section to measure the adaptability of both materials. All samples were photographed under the SEM at three different magnifications (×1000). The gap thickness between the root end filling material and the retro cavity dentine walls were measured at seven selected points at the material-dentine interface in micrometers (µm). Results: Nano MTA and MTA showed no statistically significant difference in the gap thickness between dentin-material interface in both longitudinal and transverse sections. Regarding the sealing ability, the mean value in MTA was (3.27±0.77), while the mean in Nano-MTA was (3.15±0.71). Regarding the adaptability, the mean value in MTA was (2.46±0.60), while the mean in Nano-MTA was (2.05±0.712). Both materials showed good sealing ability and good adaptation to the dentinal wall. Conclusion: Nano MTA revealed good sealing ability and adaptability comparable to MTA when used as a retrograde filling material.

An In Vitro Comparative Evaluation of Distribution of Three Different Sealers by Single-Cone Obturation Technique

Aim:

The aim of this study was to evaluate the distribution of sealer at different levels of the root canal using three different sealers in a single-cone obturation technique.

Materials and Methods:

Thirty freshly extracted mandibular premolar teeth were selected and access opening was performed. Working length was determined. Cleaning and shaping were done till 25 size K file followed by ProTaper till F2 size. Teeth were then obturated with matching gutta-percha points with the following sealers: Group I, 10 teeth with zinc oxide eugenol sealer; Group II, 10 teeth with AH plus sealer; and Group III, 10 teeth with NanoSeal-S sealer. Teeth were cross sectioned at 3 and 6 mm from the apex. Color photographs of sections were taken at a magnification of ×40 using a camera connected to a stereo-operating microscope and the images were transferred to a computer. Sealer distribution was observed and the canal perimeters coated or uncoated with the sealer can be calculated using a computer digital imaging system.

Results:

Of the three groups, zinc oxide eugenol showed least sealer distribution. AH Plus and Nanoseal-S showed no significant difference between the distribution at the 3- and 6-mm levels.

Conclusion:

Both AH Plus and Nanoseal-S showed excellent sealer distribution when compared to zinc oxide eugenol.

A quantitative evaluation of sealing ability of 4 obturation techniques by using a glucose leakage test

OBJECTIVE

The aim of this study was to evaluate the sealing ability of 4 different obturation techniques by using a glucose leakage test.

STUDY DESIGN

Eighty extracted single-rooted maxillary incisors were selected for the study. The teeth were decoronated and the root canals prepared using ProFile rotary instruments to an apical dimension of size 40 (0.06 taper). The specimens were then randomly divided into 4 experimental groups (n = 15) and filled with gutta-percha and sealer by using either cold lateral compaction, warm vertical compaction, Thermafil, or the E & Q Plus system. Another 10 teeth each served as the positive and negative controls. A glucose leakage model was used for quantitative evaluation of the coronal-to-apical microleakage at 24 hours, 1, 2, 3, 5, 8, and 12 weeks.

RESULTS

No significant difference in the cumulative amount of leakage was found among the 4 groups at 24 hours and 1 week (Kruskal-Wallis test, P > .05). Lateral compaction showed significantly more leakage than the other 3 techniques at longer intervals (Mann-Whitney U test, P < .008). No significant difference was found between vertical compaction, Thermafil, and E & Q Plus at all observation times.

CONCLUSIONS

Warm vertical compaction, Thermafil, and the E & Q Plus system showed a better sealing result than cold lateral compaction of gutta-percha at extended observation periods. The glucose leakage method used in this study was able to provide a nondestructive, quantitative, and long-term evaluation of the sealing ability of root canal fillings.

"In vitro" evaluation of the apical sealing of root canals obturated with different techniques

The purpose of this study was to compare the apical sealing of root canals obturated with different techniques. One hundred-six human mandibular incisors were submitted to instrumentation by means of the step-back technique. After instrumentation, one hundred teeth received an impermeable coating on the external surfaces of the crown and root (except for the area nearby the apical foramen). Afterwards, they were divided in five groups containing twenty elements each, according to the obturation technique employed: 1. lateral condensation with Kerr file; 2. continuous wave of condensation technique with System B; 3. thermoplasticized injectable gutta-percha technique with the Ultrafil system; 4. mechanically thermoplasticized gutta-percha with the JS Quick-Fill system and 5. thermoplasticized gutta-percha associated to a master cone with the Microseal system. The six remaining teeth were employed as negative and positive controls. After obturation, the access cavities were sealed and the teeth were immersed in aqueous 2% methylene blue dye for 72 hours at 37ºC. After that, the teeth were longitudinally sectioned and the apical microleakage was evaluated in a stereomicroscope. The Microseal system presented the best apical sealing ability, followed by System B, JS Quick-Fill, Ultrafil and the lateral condensation technique. The statistical analysis of the results demonstrated that: 1. the Microseal system presented an apical sealing similar to System B and better than the other groups; 2. System B presented better apical sealing than the lateral condensation technique, being similar to the other groups; and 3. the lateral condensation, Ultrafil and JS Quick-Fill groups demonstrated similar sealing ability.

Effect of Nd:YAG laser irradiation on the apical leakage of obturated root canals: an electrochemical study

AIM

The purpose of this laboratory study was to evaluate the effect of Nd:YAG laser irradiation on the apical leakage of obturated root canals using an electrochemical method.

METHODOLOGY

Forty extracted single-rooted teeth were selected and the anatomic crown of each tooth was removed. The specimens were randomly divided into four groups. In group 1, the root canals were prepared with K-files and irradiated with Nd:YAG laser (5 W, 20 Hz) via a 300 microns optical fibre. Then the root canals were obturated with laterally condensed gutta-percha and Pulp Canal Sealer EWT. In group 2, the root canals were treated with the same method as those of group 1 but without laser irradiation. In group 3, the root canals were prepared with ProFiles, laser irradiated and then obturated with vertically condensed gutta-percha and Pulp Canal Sealer EWT. In group 4, the root canals were treated with the same method as those of group 3 but without laser irradiation. The electric resistance between standard and experimental electrodes in the canals was measured over a period of 10 days.

RESULTS

At 2 h, groups 1 and 3 irradiated with laser had significantly less apical leakage than group 2 (P < 0.05). After 10 days, group 4 had the highest leakage, followed by groups 2, 1 and 3; the differences between the groups was statistically significant (P < 0.05).

CONCLUSIONS

Laser irradiation following root canal preparation reduced apical leakage following root canal obturation.

Coronal leakage following three obturation techniques

AIM

To compare coronal bacterial and India ink leakage in three different obturation techniques with the smear layer having been removed.

METHODOLOGY

Seventy extracted single-rooted teeth were instrumented to an apical preparation size 7 Profile Series 29 (Tulsa Dental Products, Tulsa, OK, USA). The smear layer was removed and 20 teeth were randomly obturated with lateral compaction, 20 teeth with vertical compaction, and 20 teeth with Thermafil (Tulsa Dental Products, Tulsa OK, USA). Ten teeth were used for positive (five teeth) and negative (five teeth) controls. Teeth were stored for 90 days in 100% humidity, then subjected coronally to Proteus vulgaris for 21 days to assess bacterial leakage. Following bacterial challenge, India ink was placed coronally for a further 21 days, then scored according to depth of dye leakage.

RESULTS

Vertical compaction leaked significantly less than lateral compaction during bacterial challenge. However, when dye was used there were no significant differences.

CONCLUSIONS

Bacterial leakage and dye leakage demonstrated considerable variability. The use of a dye following bacterial testing may highlight the failure of experimental devices and vertical root fractures, thus avoiding false positive results found with bacterial testing alone.

Young's modulus of warm and cold gutta-percha

The purpose of this study was to evaluate the Young's modulus of cold and warm gutta-percha. Rods of gutta-percha. Specially designed by three companies were tested at 20 degrees C and 55 degrees C with a tensile testing machine. The Young's modulus, the yield strength and the percentage of deformation were automatically recorded. There was a statistically significant difference, for the three criteria, between the cold and warm gutta-percha. Warm gutta-percha presented a Young's modulus 100 times smaller, a yield strength 2 times smaller but a percentage of permanent deformation 10 times higher than cold gutta-percha. Gutta-percha Hygenic presented the best characteristics.

An in-vitro study of smear layer removal and microbial leakage along root-canal fillings

The objective of this study was to determine the effect of removal of the smear layer on canal obturation as measured by penetration of bacteria from a coronal direction. Fifty-four extracted human teeth were decoronated and instrumented in a uniform manner. Following instrumentation the root canals of 20 teeth were rinsed with 17% EDTA and 5.25% NaOCl to remove the smear layer before obturation. A second group of 20 teeth were flushed with NaOCl alone. The teeth of both groups were obturated with Thermafil plastic carriers and Roth's sealer. The root canals of another 10 teeth, five rinsed with EDTA and five without, were obturated with Thermafil without sealer. Two teeth serving as positive controls were instrumented but not obturated, while another set of two were sealed coronally and apically to serve as negative controls. The root surface of each tooth was sealed with nail varnish. A small chamber was thoroughly sealed around the coronal aspect of each tooth so that bacteria placed therein could move only through the obturated canal space. Each tooth was placed in a test tube containing sterile trypticase soy broth (TSB). An inoculum of Proteus vulgaris in TSB was placed in each coronal chamber at five day intervals and daily observations were made for bacterial growth in the apical reservoir for 21 days. Both positive control teeth showed bacterial penetration after 24 h. Neither of the two negative control teeth demonstrated penetration for the duration of the study. The frequency of bacterial penetration through teeth obturated with intact smear layer (70%) was-significantly greater than that of teeth from which the smear layer had been removed (30%) P < 0.05. All but one tooth obturated without sealer exhibited bacterial penetration, irrespective of the presence or absence of smear layer. Removal of the smear layer enhanced sealability as evidenced by increased resistance to bacterial penetration.

Comparison of the sealing ability of laser-softened, laterally condensed and low-temperature thermoplasticized gutta-percha

This study compared the effectiveness of four different techniques used for obturation of single rooted-teeth: lateral condensation, low-temperature gutta-percha (Ultrafil), vertical condensation of gutta-percha softened by means of three different laser devices (argon, CO2, and Nd:YAG), or composite resin photopolymerized by argon laser. Seventy single-rooted teeth were instrumented using a step-back technique and obturated using one of the methods listed previously. To evaluate apical sealing effectiveness techniques, samples were subjected to 1% methylene blue dye at 37 degrees C for 7 days. The most extensive dye penetration (4.3 mm) was observed in teeth obturated with composite resin, followed by gutta-perch laser with CO2 (2.15 mm), and the Nd:YAG laser (3.54 mm). Gutta-percha softened with argon laser created an apical seal almost identical to that obtained with the lateral condensation and Ultrafil techniques (1.50, 1.45, and 1.48 mm of leakage, respectively). These results indicate that the argon laser can be used for gutta-percha softening to produce good apical sealing results.

Dentinal heat transmission induced by a laser-softened gutta-percha obturation technique

In this study, intracanal laser-softened gutta-percha, Ultrafil, and intracanal laser-cured composite resin techniques were compared with respect to the temperature elevation induced on the outer root surface. The temperature at the root surface of 50 single-rooted teeth was measured using a thermovision camera. Argon laser produced a rise in temperature of +12.9 degrees C (gutta-percha) and +13.3 degrees C (composite resin), respectively. The CO2 laser produced +10.3 degrees C and Nd:YAG laser produced the highest temperature elevation of +14.4 degrees C. Low-temperature gutta-percha obturation technique did not produce a measurable temperature change on the external root surfaces.

In vitro endotoxin penetration of coronally unsealed endodontically treated teeth

The purpose of the study was to evaluate the penetration of bacterial endotoxin (L.P.S.) through obturated root canals. Twenty-four single-rooted teeth were instrumented in a uniform manner. The root canals of 16 teeth were obturated with guttapercha and Roth's sealer and 8 teeth were similarly obturated but without sealer. The teeth were then divided into three groups. Group 1-Positive control (4 teeth). Teeth obturated without sealer were used. Sticky wax was softened in an open flame and painted over the external root surface except the apical 2 mm and coronal canal orifice which were left free of the sticky wax. Group 2-Negative control (4 teeth). Again teeth without sealer comprised the teeth in this group. However, in this group the sticky wax covered the apical area of the root and the canal orifice coronally, in addition to the rest of the root. Group 3-Experimental (16 teeth). The teeth obturated in conjunction with sealer were used. Otherwise the teeth were treated as in group 1. The coronal root half was then hermetically sealed from the apical root half so that LPS placed coronally could move only through the obturated canal space to the apical segment. One ml of water containing 100 micrograms/ml endotoxin was placed in the upper chambers and pyrogen-free water in the lower chambers. The upper and lower chambers were then tested for endotoxin at different time periods upto 21 days. The upper chambers tested positive for endotoxin at all test times for all teeth. All 4 positive control teeth showed endotoxin in the lower chambers by 24 hrs.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of sealing properties of Thermafil and Ultrafil techniques in the absence or presence of smear layer

The apical sealing abilities of two thermoplasticized gutta-percha techniques were evaluated. A total of 128 single-rooted teeth were divided into six groups in which Ultrafil, Thermafil, and lateral condensation techniques, with and without the smear layer, were used to obturate 20 roots in each group. The roots were implanted subcutaneously in rats for 90 days to expose the materials to vital tissue and tissue fluids. The roots were recovered, immersed in 1% methylene blue for 2 wk, cleared, and the dye penetration was measured using a dissecting microscope. Thermafil showed the least leakage with smear layer present and Ultrafil the least with it absent. The two thermoplasticized gutta-percha techniques both showed significantly less leakage than lateral condensation with and without the smear layer. Removing the smear layer reduced the leakage significantly in all groups.

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.

Endodontic leakage studies reconsidered. Part I. Methodology, application and relevance

An increasing number of endodontic leakage studies have been published. In the 1990 volumes of Journal of Endodontics and International Endodontic Journal, there was one leakage study to every 4.3 scientific articles. The most popular method was linear measurement of tracer (dye or radioisotope) penetration along a root filling. Comparing some data on linear measurement of dye penetration following the cold lateral condensation of gutta-percha that were published between 1980 and 1990, a high level of variation has been found, although the experimental methods used in these studies were quite similar. In almost all studies evaluating various techniques, the cold lateral condensation technique has been used as a standard control for comparison. The reliability of these results is questionable. The problems with such studies are discussed. It seems that more research should be done on leakage study methodology, instead of continuing to evaluate the sealing ability of different materials and techniques by methods that may give little relevant information.

Sealing ability of Thermafil with and without sealer

The purpose of this study was to evaluate the apical sealing ability of root canals filled using three obturating techniques. Sixteen maxillary first molars were obturated with Thermafil, 16 with Thermafil and a ZOE sealer, and 16 with laterally condensed gutta-percha. Two canal instrumentation methods were used, conventional step-back preparation with K-Flex files and traditional instrumentation combining reaming with reamers and filing with K-Flex files. Following obturation, the teeth were prepared for evaluation of the seal using India ink and a Profile Projector. The depth of penetration of the dye was statistically evaluated for each of the three roots with an analysis of variance. For sealing ability, there was no significant difference at the p < 0.05 level between the conventional step-back preparation and the traditional instrumentation technique. However, a significant difference was present at the p < 0.05 level for the obturation techniques. The mean linear dye penetration for the Thermafil technique was greater than that for lateral condensation.