Microleakage associated with retrofilling of the apical two thirds with amalgam

In this investigation the effect of increasing the thickness of amalgam retrofilling on its sealing ability was studied and compared with the sealing ability of the laterally condensed gutta-percha with a sealer. The apical two thirds of the canals of 118 upper central incisors, filled with laterally condensed gutta-percha, were sealed with amalgam. Amalgam retrofills were also used to seal the apices of the roots of six teeth that had no other filling in their canals. The effectiveness of both techniques was determined by their ability to inhibit the penetration of methylene blue dye for the periods of 24 hours, 1 week, and 1, 3, and 6 months. At 24 hours both materials showed comparable sealing ability. However, the sealing ability of laterally condensed gutta-percha was significantly better than that of amalgam from the 1-week period until the end of the study. The depth of marginal penetration around both materials increased with time. The amount of the dye penetration increased acutely around amalgam, whereas its increase around gutta-percha was more uniform. At the end of the study, specimens retrofilled with amalgam exhibited total dye penetration that exceeded the full thickness of amalgam (6 mm) and spread into the root canal space. On the other hand, the mean value for marginal penetration of the dye around the laterally condensed gutta-percha was 2.6 mm at the end of the study. The present investigation proved beyond doubt that the use of any thickness of retrograde amalgam to seal the apex, with no other filling within the canal, invites failure.     

The sealing ability of amalgam used as a retrograde root filling in endodontic surgery

A dye penetration technique was used to investigate the sealing ability of amalgam retrograde root fillings in vitro. A factorial design was employed to determine the effect of amalgam fillings of 1, 2 and 4 mm in length with and without prior filling of the canals with gutta-percha. The results were compared with a group of teeth filled with laterally condensed gutta-percha alone and another with laterally condensed gutta-percha plus root resection but with no retrograde filling. It was concluded that increasing the length of the amalgam filling did not improve the seal, that prior filling of the canal did not improve the seal, that retrograde root fillings were no worse than laterally condensed gutta-percha alone and that root resection of teeth filled with laterally condensed gutta-percha without retrograde filling was no worse than those filled with laterally condensed gutta-percha without root resection or retrograde root filling.     

Comparison of apical sealing methods. A preliminary report.

A comparison of the seal provided by gutta-percha root canal filling, heat-sealed gutta-percha, retrograde amalgam filling, and retrograde Durelon filling was made by observation of dye penetration around the above filling materials in extracted teeth. A small but not significant difference between gutta-percha, heat-sealed gutta-percha, and retrograde amalgam was noted. Retrograde Durelon filling gave a poor seal in comparison to gutta-percha and retrograde amalgam filling, but the difference between it and the heat seal was not significant.     

Sealing quality of a newly designed root canal filling material following apicectomy compared with amalgam and heat-sealed gutta-percha

A newly designed root canal filling material, prepared by coating silver cones with guttapercha, was compared with heat-sealed gutta-percha and amalgam to evaluate its effectiveness as a root canal sealer using a dye penetration method in vitro. The study indicated that silver-percha cones are more effective in their sealing ability than retrograde amalgam and heat-sealed gutta-percha. The heat-sealed gutta-percha was shown to provide an inferior seal.     

Cyanoacrylate as a retrofilling material

The sealing ability of cyanoacrylate as a retrograde root canal filling material was evaluated in vitro. Fifty roots were cleansed, shaped, and assigned to five groups of ten roots each. The root canals were obturated with gutta-percha and Grossman's sealer. The apical 2 mm of each root in the five groups was resected. In groups I, II, and III, retrofilling preparation was made and filled with amalgam, varnish and then amalgam, and cyanoacrylate, respectively. In group IV, a hot instrument was used to seal the gutta-percha, and in group V, a cold burnisher was used for the same purpose. All of the teeth were immersed in 1% methylene blue dye for 24 hours and sectional longitudinally; dye penetration was then measured. One-way analysis of variance performed on the means of the groups indicated that group III had the least amount of leakage (p less than 0.05). This study indicates that cyanocrylate may have potential as a retrograde filling material.     

A comparison of laterally condensed gutta-percha, thermoplasticized gutta-percha, and mineral trioxide aggregate as root canal filling materials

The purpose of this study was to evaluate the potential of using mineral trioxide aggregate as a root canal filling material by comparing its apical sealing ability with that of laterally condensed gutta-percha with sealer and high-temperature thermoplasticized gutta-percha with sealer in extracted bovine teeth. Sixty bovine incisors with single canals were prepared in a standard manner using LightSpeed instruments, randomly divided into three groups of 20 teeth, and obturated. The sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 3 days. The teeth were cleared, and the linear extent of dye penetration was measured with a stereomicroscope. Data were analyzed by the Kruskal-Wallis one-way ANOVA followed by Dunn's test. Canals filled with laterally condensed gutta-percha or thermoplasticized gutta-percha showed significantly less apical dye penetration than canals obturated with mineral trioxide aggregate (p < 0.001). There was no significant difference in leakage between the laterally condensed group and the thermoplasticized group. The results suggest that gutta-percha obturation may provide an apical seal that is superior to MTA.     

Sealing ability of amalgam, super EBA cement, and MTA when used as retrograde filling materials

OBJECTIVE: To compare apical microleakage of MTA following reverse retrograde root filling with that following amalgam and EBA retrofilling. DESIGN: Prospective random control trial. SETTING: It was conducted at the University of Jordan in 1998. MATERIALS AND METHODS: The root canals of 79 extracted teeth were instrumented and obturated with vertically condensed gutta-percha. Each tooth was apically resected and the apex was prepared ultrasonically to 3 mm depth and the root surface isolated with nail varnish. Teeth were divided randomly into three groups of 25 teeth each. First group was retrofilled with amalgam, second group with EBA and the third group with MTA. Following immersion in 1% methylene blue dye for 72 hours, the roots were sectioned and the depth of dye penetration was evaluated by a stereomicroscope at x10 magnification. INTERVENTIONS: Super EBA is a reinforced zinc oxide cement based on a mixture of 32% eugenol and 68% ethoxy benzoic acid (EBA). MTA is a mineral trioxide aggregate cement (MTA) based on a mixture of sterile water. MAIN OUTCOME MEASURES: The sealing effectiveness of the retrograde filling materials used in this study was determined by their ability to inhibit dye penetration. RESULTS: 56% of the group filled with amalgam and 20% of the group filled with EBA showed dye leakage beyond the retrofilling material whereas the MTA group showed none, two samples from MTA group were eliminated because of their fractured roots. The chi-squared test revealed a statistically significant difference among all three groups (P < 0.05). CONCLUSION: MTA cement provides a better seal than amalgam and EBA cement when used as retrograde filling, but the extrapolation of this result into a clinical practice may be questionable.     

The sealing ability of materials used as retrograde root fillings in endodontic surgery

The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light-cured composite resin, dentine bonding agent, and light-cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light-cured composite resin, light-cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta-percha, amalgam plus cavity varnish and EBA cement.     

Longitudinal evaluation of the seal of endodontic retrofillings

The apical seal obtained with various retrofilling materials placed in prepared, extracted human anterior teeth was measured at various time intervals. Materials evaluated were cold-burnished gutta-percha, amalgam, amalgam with a cavity varnish, SuperEBA cement, and a glass ionomer restorative material (Ketac-Silver). Control groups included teeth retrofilled with either gutta-percha without sealer or TERM. The root canals were cleaned and shaped and the root ends were prepared for retrofilling. The materials were placed into the preparations and allowed to set for 24 h. Microleakage was measured at 24 h, 1, 2, and 3 wk, and 1, 2, and 3 months after insertion of the retrofilling using a fluid filtration technique. Multiple range analysis indicated that Ketac-Silver produced a significantly inferior seal when compared with the other materials at all time periods. There was no significant difference among SuperEBA, amalgam, and amalgam with a cavity varnish.     

Evaluation of sealing properties of 70°C thermoplasticized gutta-percha used as a retrograde root filling

The efficacy of low temperature (70 degrees C) thermoplasticized gutta-percha used to seal root canals by the retrograde approach following apicectomy was assessed. A dye leakage technique was used, and gutta-percha was compared with amalgam. Two groups of different sized roots were apicected, and their root canals instrumented and filled conventionally with laterally condensed gutta-percha. Each group was randomly divided into four sub-groups; one was the control group in which no further treatment was carried out. In the other three groups the apical 3 mm of gutta-percha was removed, and the apical cavities filled as follows: group I with 70 degrees C thermoplasticized gutta-percha with sealer; group II with 70 degrees C thermoplasticized gutta-percha without sealer; group III with amalgam. The roots were rendered transparent by acid demineralization, and maximum dye penetration was measured. The results showed statistically significant ranking of leakage between the four sub-groups: 70 degrees C thermoplasticized gutta-percha with sealer less than 70 degrees C thermoplasticized gutta-percha without sealer less than amalgam less than control. The larger canals in all four sub-groups also exhibited significantly greater leakage than the smaller ones.     

Leakage in vitro with high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials

An in vitro dye leakage study was performed to compare the sealing ability of high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials. Forty-five extracted anterior teeth were obturated with gutta-percha, the apical 3 mm of the roots were resected, and 2-mm-deep retrograde preparations were prepared. The roots were then randomly placed into three groups and retrofilled with one of the experimental materials. After 72 h in India ink, the teeth were cleared and evaluated for leakage using a stereomicroscope. No leakage was evident in the three teeth used as negative controls. Complete leakage was noted in the three positive control teeth. Statistical analysis of the results showed that high-temperature thermoplasticized gutta-percha had significantly less leakage than did high copper amalgam.     

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.     

Does cold burnishing gutta-percha create a better apical seal?

This study investigated the seal created by cold burnishing the gutta-percha exposed after apical root resection of endodontically treated teeth. Sixty single-rooted extracted human teeth with a single straight canal were divided into four experimental groups of 15 teeth each. In two of the experimental groups the canals were instrumented and obturated well with laterally condensed gutta-percha and sealer. The remaining two groups were instrumented and poorly obturated with laterally condensed gutta-percha and sealer. The apical 2 mm of all the teeth were then resected and the effect of cold burnishing the exposed gutta-percha was investigated using a linear dye penetration technique. Under the condition of this study, cold burnishing gutta-percha after apical root resection of a well-obturated root canal resulted in a poorer apical seal than if no burnishing were performed. Cold burnishing the exposed gutta-percha after apical root resection of poorly obturated root canals improved the apical seal as compared with nonburnished poorly obturated canals.     

Effect of apical resections and reverse fillings on Thermafil root canal obturations

This in vitro dye leakage study examined the influence of apical root resection and reverse amalgam fillings on the apical seal of root canals obturated with Thermafil. Fifty human canine teeth were instrumented and obturated with either laterally condensed gutta-percha or Thermafil using Roth's zinc oxide-eugenol Type I regular sealer. After 24 h, one of the following additional procedures was performed on 30 of the teeth: 2-mm apical resection, 4-mm apical resection, and 2-mm apical resection plus reverse amalgam filling 2 mm in depth and diameter. The external root surfaces were coated with enamel paint and the teeth were exposed to 1% methylene blue dye at 37 degrees C for 2 wk. The roots were split longitudinally and the depth of linear dye penetration was measured through a stereozoom microscope. Statistical analysis showed no significant differences in the linear dye penetration among the various groups of teeth.     

A comparison of the marginal leakage of retrograde techniques

An investigation of the apical seal of the most popular retrograde techniques was attempted. Ninety extracted maxillary central incisors were instrumented and obturated, and various apical procedures were performed. The depth of penetration of 2 percent methylene blue dye was used to evaluate the apical seal. Retrograde amalgam, heat-sealed gutta-percha, and the apicoectomy control showed average depths of penetration of 3.1, 4.0, and 4.6 mm., respectively, while cold-burnished gutta-percha yielded an average depth of penetration of 1.5 mm. The apical seal produced by cold-burnished gutta-percha allows less than half the penetration of the best of the other techniques and gave the most consistent results.     

The apical seal via the retrosurgical approach. I.A. preliminary study

The results of this study indicated that heat-sealed gutta-percha alone and when reinforced with Adaptic or a glass ionomer cement provided the most effective apical seal. It is therefore proposed to expand this study to include these materials and zinc-free Spheraloy and Cupralloy amalgams as retrofilling materials. The amalgams will be used with and without cavity varnish.     

An in vitro evaluation of injectable thermoplasticized gutta-percha, glass ionomer, and amalgam when used as retrofilling materials

An in vitro dye leakage study was performed to evaluate the sealing ability of the following retrofilling materials: high- and low-temperature injectable thermoplasticized gutta-percha with and without sealer, a glass ionomer cement, and amalgam with and without varnish. The roots of 105 extracted human maxillary anterior teeth were instrumented and obturated with single cones of gutta-percha and sealer. The apical 3 mm of the roots were then resected and 2-mm deep retrograde preparations were prepared. Each root was then randomly placed into one of seven groups and retrofilled with one of the test materials. After 72 h in India ink, the roots were cleared and evaluated for leakage using a stereomicroscope. Statistical analysis of the results indicated that injectable high-temperature gutta-percha without sealer demonstrated significantly more leakage than the other materials. There were no significant differences in leakage among the other evaluated materials.     

The adaptation and sealing ability of light-cured glass ionomer retrograde root fillings

The adaptation and sealing ability of a light-cured glass ionomer cement when used as a retrograde root filling was assessed using a confocal optical microscope with and without a fluorescent dye. This material was compared with a conventional glass ionomer cement and amalgam. The root canals of 60 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were apicected, retrograde cavities were prepared, and then divided into three groups of 20 teeth each and filled with the test materials. The light-cured glass ionomer cement was well adapted to the retrograde cavity and apicected root surface. Within the retrograde cavity the cement was often well adapted to one wall, but gaps were found on the opposite cavity wall. This was probably caused by the polymerization contraction of the material. In contrast, the amalgam retrograde root fillings were poorly adapted to the cavities, with gaps between the cavity walls and amalgam. This group exhibited the poorest sealing ability as measured by the extent of dye penetration. The conventional glass ionomer cement was often found smeared over the root face, and there were unfilled voids at the base of some retrograde cavities. The results of the dye leakage study were analysed statistically. The sealing ability of the light-cured glass ionomer cement was significantly better than that of amalgam (P less than 0.001). The dye penetration around the light-cured glass ionomer cement and the conventional glass ionomer cement was not significantly different (P greater than 0.05). However, the sealing ability of the conventional glass ionomer cement was significantly better than that of amalgam (P less than 0.05).     

Retrograde seal in ultrasonically prepared canals

The sealing ability of various retrofilling materials was compared. The root canals of 85 single-rooted teeth were cleansed and obturated with gutta-percha without sealer using lateral condensation. The apical 3 mm of the roots were resected and divided into positive control, negative control, and five experimental groups. The experimental teeth received root-end cavity preparation to 3 mm depth using an ultrasonic retroprep tip. The retrocavities were dried and divided into five groups to receive the following materials: amalgam with varnish, amalgam with Clearfil Liner Bond II, thermoplasticized gutta-percha (TGP) with sealer, Ketac-fil, and Super-EBA. After immersion in India ink for 7 days, the roots were demineralized, cleared, and evaluated for dye leakage under a stereomicroscope. Statistical analysis showed that Super-EBA, Ketac-fil, and TGP with sealer demonstrated less leakage than amalgam with varnish and amalgam with Clearfil Liner Bond II (p < 0.05). Super-EBA also leaked significantly less than Ketac-fil or TGP sealer (p < 0.05). No significant difference was found between Ketac-fil and TGP or between the two groups filled with amalgam (p > 0.05).     

A 24-week study of the microleakage of four retrofilling materials using a fluid filtration method.

The microleakage after retrofillings of amalgam, amalgam with cavity varnish, silver-containing glass ionomer cement, and intermediate restorative material was compared in vitro. Thirty-six extracted human incisors and canines were instrumented, obturated with gutta-percha without sealer, subjected to apicoectomy, and retrofilled with the materials described above. After removal of the gutta-percha filling, the microleakage from both directions (apically and coronally) was measured quantitatively and longitudinally for 24 wk after filling by a fluid filtration technique. All four retrofilling materials revealed some apical and coronal leakage at all time periods. The amalgam group showed statistically significant (p less than 0.001) apical leakage at 1.5 h. The use of cavity varnish significantly reduced the apical leakage of the amalgam group at 1.5 h. The silver-containing glass ionomer cement and intermediate restorative material groups showed significantly (p less than 0.05) less coronal leakage compared with the amalgam group at 1.5 h. Scanning electron microscopy of selected samples showed marginal defects of approximately 5 microns between the root dentin and the retrofilling material.