Longitudinal evaluation of the seal of endodontic retrofillings

Materials for retrograde filling in root canal therapy

BACKGROUND

Root canal therapy is a sequence of treatments involving root canal cleaning, shaping, decontamination, and obturation. It is conventionally performed through a hole drilled into the crown of the affected tooth, namely orthograde root canal therapy. When it fails, retrograde filling, which seals the root canal from the root apex, is a good alternative. Many materials are used for retrograde filling. Since none meets all the criteria an ideal material should possess, selecting the most efficacious material is of utmost importance. This is an update of a Cochrane Review first published in 2016.

OBJECTIVES

To determine the effects of different materials used for retrograde filling in children and adults for whom retrograde filling is necessary in order to save the tooth.

SEARCH METHODS

An Information Specialist searched five bibliographic databases up to 21 April 2021 and used additional search methods to identify published, unpublished, and ongoing studies. We also searched four databases in the Chinese language.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) that compared different retrograde filling materials, with the reported success rate that was assessed by clinical or radiological methods for which the follow-up period was at least 12 months.

DATA COLLECTION AND ANALYSIS

Records were screened in duplicate by independent screeners. Two review authors extracted data independently and in duplicate. Original trial authors were contacted for any missing information. Two review authors independently assessed the risk of bias of the included studies. We followed Cochrane's statistical guidelines and assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included eight studies, all at high risk of bias, involving 1399 participants with 1471 teeth, published between 1995 and 2019, and six comparisons of retrograde filling materials. - Mineral trioxide aggregate (MTA) versus intermediate restorative material (IRM): there may be little to no effect of MTA compared to IRM on success rate at one year, but the evidence is very uncertain (risk ratio (RR) 1.09, 95% confidence interval (CI) 0.97 to 1.22; I2 = 0%; 2 studies; 222 teeth; very low-certainty evidence). - MTA versus super ethoxybenzoic acid (Super-EBA): there may be little to no effect of MTA compared to Super-EBA on success rate at one year, but the evidence is very uncertain (RR 1.03, 95% CI 0.96 to 1.10; 1 study; 192 teeth; very low-certainty evidence). - Super-EBA versus IRM: the evidence is very uncertain about the effect of Super-EBA compared with IRM on success rate at 1 year, with results indicating Super-EBA may reduce or have no effect on success rate (RR 0.90, 95% CI 0.80 to 1.01; 1 study; 194 teeth; very low-certainty evidence). - Dentine-bonded resin composite versus glass ionomer cement: compared to glass ionomer cement, dentine-bonded resin composite may increase the success rate of the treatment at 1 year, but the evidence is very uncertain (RR 2.39, 95% CI 1.60 to 3.59; 1 study; 122 teeth; very low-certainty evidence). Same result was obtained when considering the root as unit of analysis at one year (RR 1.59, 95% CI 1.20 to 2.09; 1 study; 127 roots; very low-certainty evidence). - Glass ionomer cement versus amalgam: the evidence is very uncertain about the effect of glass ionomer cement compared with amalgam on success rate at one year, with results indicating glass ionomer cement may reduce or have no effect on success rate (RR 0.98, 95% CI 0.86 to 1.12; 1 study; 105 teeth; very low-certainty evidence). - MTA versus root repair material (RRM): there may be little to no effect of MTA compared to RRM on success rate at one year, but the evidence is very uncertain (RR 1.00, 95% CI 0.94 to 1.07; I2 = 0%; 2 studies; 278 teeth; very low-certainty evidence). Adverse events were not assessed by any of the included studies.

AUTHORS' CONCLUSIONS

Based on the present limited evidence, there is insufficient evidence to draw any conclusion as to the benefits of any one material over another for retrograde filling in root canal therapy. We conclude that more high-quality RCTs are required.

An In Vitro Comparative Evaluation of Apical Leakage Using Different Root Canal Sealers

Background

Successful endodontic therapy requires a fluid-tight apical seal. The aim of this in vitro study was to evaluate and compare the apical sealing ability of 3 root canal sealers: Apexit Plus, AH Plus, and Resilon/Epiphany sealers.

Material/Methods

Samples of 152 single-rooted teeth were divided into 2 test groups, and each group was divided into 3 subgroups based on the preparation and obturation technique. After preparation with the step-back technique, the first group of root canals were obturated with lateral gutta-percha compaction in combination with AH Plus sealer or Apexit Plus or with the Resilon/Epiphany system alone. In the second group, preparation was done with the crown-down technique and root canals were then obturated with Thermafil obturator in combination with AH Plus or Apexit Plus or with Resilon/Epiphany sealer alone. Apical leakage was determined using a dye leakage test observed with a stereomicroscope. The degree of dye leakage was assessed using the t test to comparing the arithmetic averages of the groups.

Results

In the groups prepared with the step-back technique, the average dye leakage was lower in samples obturated with Resilon/Epiphany, than in those filled with AH Plus/lateral gutta-percha compaction or Apexit Plus/lateral gutta-percha compaction. In groups prepared with the crown-down technique and obturated with the Resilon/Epiphany system, the average dye leakage was lower than in those filled with AH Plus/Thermafil obturation and those filled with Apexit Plus/Thermafil obturation.

Conclusions

Although all preparation and obturation techniques showed dye penetration, the crown-down technique paired with the Resilon/Epiphany system showed the least leakage.

Materials for retrograde filling in root canal therapy

BACKGROUND

Root canal therapy is a sequence of treatments involving root canal cleaning, shaping, decontamination and obturation. It is conventionally performed through a hole drilled into the crown of the affected tooth, namely orthograde root canal therapy. For teeth that cannot be treated with orthograde root canal therapy, or for which it has failed, retrograde root filling, which seals the root canal from the root apex, is a good alternative. Many materials, such as amalgam, zinc oxide eugenol and mineral trioxide aggregate (MTA), are generally used. Since none meets all the criteria an ideal material should possess, selecting the most efficacious material is of utmost importance.

OBJECTIVES

To determine the effects of different materials used for retrograde filling in children and adults for whom retrograde filling is necessary in order to save the tooth.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 13 September 2016); the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 8) in the Cochrane Library (searched 13 September 2016); MEDLINE Ovid (1946 to 13 September 2016); Embase Ovid (1980 to 13 September 2016); LILACS BIREME Virtual Health Library (1982 to 13 September 2016); and OpenSIGLE (1980 to 2005). ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. We also searched Chinese BioMedical Literature Database (in Chinese, 1978 to 20 September 2016); VIP (in Chinese, 1989 to 20 September 2016); China National Knowledge Infrastructure (in Chinese, 1994 to 20 September 2016); and Sciencepaper Online (in Chinese, to 20 September 2016). No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) only that compared different retrograde filling materials, with reported success rate that was assessed by clinical or radiological methods for which the follow-up period was at least 12 months.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently and in duplicate. Original trial authors were contacted for any missing information. Two review authors independently carried out risk of bias assessments for each eligible study following Cochrane methodological guidelines.

MAIN RESULTS

We included six studies (916 participants with 988 teeth) reported in English. All the studies had high risk of bias. The six studies examined five different comparisons, including MTA versus intermediate restorative material (IRM), MTA versus super ethoxybenzoic acid cement (Super-EBA), Super-EBA versus IRM, dentine-bonded resin composite versus glass ionomer cement and glass ionomer cement versus amalgam. There was therefore little pooling of data and very little evidence for each comparison.There is weak evidence of little or no difference between MTA and IRM at the first year of follow-up (risk ratio (RR) 1.09; 95% confidence interval (CI): 0.97 to 1.22; 222 teeth; quality of evidence: low). Insufficient evidence of a difference between MTA and IRM on success rate at the second year of follow-up (RR 1.06; 95% CI: 0.89 to 1.25; 86 teeth, 86 participants; quality of evidence: very low). All the other outcomes were based on a single study. There is insufficient evidence of any difference between MTA and Super-EBA at the one-year follow-up (RR 1.03; 95% CI: 0.96 to 1.10; 192 teeth, 192 participants; quality of evidence: very low), and only weak evidence indicating there might be a small increase in success rate at the one-year follow-up in favour of IRM compared to Super-EBA (RR 0.90; 95% CI: 0.80 to 1.01; 194 teeth; quality of evidence: very low). There was also insufficient and weak evidence to show that dentine-bonded resin composite might be a better choice for increasing retrograde filling success rate compared to glass ionomer cement at the one-year follow-up (RR 2.39; 95% CI: 1.60 to 3.59; 122 teeth, 122 participants; quality of evidence: very low). And there was insufficient evidence of a difference between glass ionomer cement and amalgam at both the one-year (RR 0.98; 95% CI: 0.86 to 1.12; 105 teeth; quality of evidence: very low) and five-year follow-ups (RR 1.00; 95% CI: 0.84 to 1.20; 82 teeth; quality of evidence: very low).None of these studies reported an adverse event.

AUTHORS' CONCLUSIONS

Based on the present limited evidence, there is insufficient evidence to draw any conclusion as to the benefits of any one material over another. We conclude that more high-quality RCTs are required.

Resistance to leakage of various thicknesses of apical plugs of Bioaggregate using liquid filtration model

AIM

The aim of this study was to compare the resistance to leakage of different thicknesses of Bioaggregate (BA) and 4-mm-thick white mineral trioxide aggregate (WMTA) in an apexification model using liquid filtration.

METHODS

32 extracted mandibular premolar teeth were sectioned at the cemento-enamel junction and 3-4 mm from the tooth apex to obtain 12-mm-long root segments. The apical and coronal thirds were prepared with size two through six Gates Glidden burs. The teeth were divided into four groups according to material and thickness, as follows: Group 1: 2-mm BA; Group 2: 4-mm BA; Group 3: 12-mm (total length) BA; Group 4: 4-mm WMTA (control). The empty parts of the roots in Groups 1, 2, and 4 were filled with gutta-percha and root canal sealer, and leakage was measured using fluid filtration. The data were analyzed using the Kruskal-Wallis H-test.

RESULTS

No statistical differences in microleakage were observed between Groups 1, 2, and 4 (P > 0.05). Group 3 (roots filled completely with BA) showed significantly less leakage than the other groups tested (P < 0.01).

CONCLUSIONS

The findings of this study showed that 12 mm of BA exhibited the best resistance to leakage. At the same time, 2-4 mm of BA showed similar results when compared to 4-mm MTA. In light of these results, this study suggests that BA may be a good candidate for further clinical studies when used as an apical barrier for apexification.

Fluid flow evaluation of coronal microleakage intraorifice barrier materials in endodontically treated teeth

Objective:

The objective of this study was to compare the coronal microleakage intraorifice barrier materials, called CoroSeal (CS), fissur sealant (FS), flowable composite FC, and policarboksilate cement (PC), by using the computerized fluid filtration method.

Materials and Methods:

Fifty freshly extracted, single-canal human maxillary central teeth were used in this study. The teeth were decoronated to a standardized root length of 15 mm. After preparation and irrigation, all the teeth were obturated with gutta-percha and AH-Plus. In all teeth, the coronal 2 mm of root filling was removed and replaced with one of the intraorifice barriers. According to intraorifice barriers, teeth were divided randomly into 4 experimental groups (n = 10) and 2 control groups (n = 5). Group 1: CS; Group 2: FS; Group 3: FC; and Group 4: PC.

Positive Control Group:

No barrier material was used.

Negative Control Group:

Roots were completely coated with the nail polish, including the orifice. Leakage was evaluated by using a computerized fluid filtration model. Differences in fluid filtration among groups were subjected to statistical analysis using the Kruskal-Wallis Test and multiple comparisons test.

Results:

A value of P < 0.05 was statistically significant. Statistical analysis has indicated that the CS leaked significantly less than other groups (P < 0.05). There was a significant difference between FS and PC (P < 0.05), in contrast there was no significant difference between FS and FC (P > 0.05).

Conclusions:

Using the CS material as an intraorrifice barrier material reduced amount of microleakage as compared with FS, FC, and PC.

Comparison of the microhardness and morphology of five different retrograde filling materials in aqueous and dry conditions

The purpose of the present study was to compare the effect of dry and aqueous conditions on the surface morphology and surface hardness of five materials 24 h after being used as fillings without initial setting time in dry condition. The five materials were ProRoot mineral trioxide aggregate (MTA), super EBA, intermediate restorative materials (IRM), zinc oxide eugenol (ZOE), and amalgam. To evaluate microhardness, the five materials were submitted to the Vickers microhardness (VHN) test. We used a scanning electron microscope (Steroscan 440, Leica Cambridge, England) to observe the microstructural morphology of the five different materials. The VHN of MTA soaked in water showed five times lower than that of MTA soaked in dry condition. On the other hand, super EBA was less influenced by the medium of storage compared with the other materials. Scanning electron microscope (SEM) images showed the similar results with microhardness tests. The surface of MTA soaked in water appeared to be unstable compared with that of dry condition while super EBA showed similarly smooth surface in both conditions (aqueous and dry). In conclusion, the physical property of MTA is reduced after storage in water; however, super EBA is less influenced by aqueous condition.

The effects of humidity and serum on the surface microhardness and morphology of five retrograde filling materials

The purpose of this study was to compare the surface morphology and surface hardness of five materials 24 h after filling, in conditions of 100% humidity, and fetal bovine serum. The five materials were ProRoot Mineral Trioxide Aggregate (MTA), Super-EBA, Intermediate Restorative Materials (IRM), Zinc Oxide Eugenol (ZOE), and Amalgam. The microhardness of these materials was evaluated by Vickers microhardness test, and their morphologies were compared by using scanning electron microscopy (SEM). To evaluate the microhardness, the mixed five materials were measured with Vickers microhardness test. Differences between the experimental groups were analyzed by two-way ANOVA and Duncan's multiple comparison tests. All analyses were performed using the Statistical Package for the Social Sciences (SPSS Inc., Chicago, IL). For the microstructural morphological evaluation, the cross cut and root-end cavity prepared surfaces followed by retrograde filling with five different materials were observed under a Scanning Electron Microscope (Steroscan 440; Leica, Cambridge, England) at ×500. To summarize, Super EBA was less influenced by storage medium than the other materials, especially MTA. However, further long-term studies considering other factors, such as biocompatibility (i.e. cellular toxicity) and retention, are needed to be collaborated with these findings in the clinical context.

Bacterial leakage of GuttaFlow-filled root canals compared with Resilon/Epiphany and Gutta-percha/AH26-filled root canals

The purpose of this study was to assess bacterial apical leakage in root canals obturated with GuttaFlow and compare this with the leakage of root canals obturated with Resilon/Epiphany or Gutta-percha/AH26. A total of 55 single-rooted human teeth were divided randomly into three experimental (n = 15) and two control groups (n = 5). Following a standardised preparation, the teeth were obturated with either GuttaFlow, Resilon/Epiphany or Gutta-percha/AH26. A two-chamber bacterial model using Enterococcus faecalis was employed to assess bacterial apical leakage for a period of 60 days. A Kruskal-Wallis test showed no significant differences between the seal of root canals obturated with GuttaFlow, Resilon/Ephiphany or Gutta-percha/AH26.

Evaluation of apical microleakage of teeth sealed with four different root canal sealers

Objectives:

to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.

Results:

AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).

Conclusions:

the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.

Evaluation of the effect of four self-etching adhesives on dentin permeability

OBJECTIVE

The aim of this study was to evaluate the effect of two two-step and two single-step self-etching adhesives on dentin permeability using a computerized fluid filtration (CFF) test method.

METHODOLOGY

Forty recently extracted sound human molar teeth were sectioned at the mid level of the crown to obtain dentin discs of 1 +/- 0.2 mm. A total of 40 discs were obtained and randomly divided into four groups (n = 10). The permeability of the discs was measured using the CFF test method before and after application of the following self-etching adhesives: Hybrid Bond, G-Bond, AdheSE, and Protect Bond. Fluid movement measurements were made at 2-min intervals for 8 min, and a mean of the values obtained was calculated for each specimen.

RESULTS

The in vitro fluid conductance of dentin discs treated with Hybrid Bond and AdheSE were lower than the dentin discs treated with G-Bond and Protect Bond (p < 0.05).

CONCLUSION

1-Treating dentin discs with self-etching adhesives caused significant reduction of dentin permeability. 2-All self-etching adhesives allowed diffusion of distilled water. However, AdheSE and Hybrid Bond showed the lowest permeability.

Sealing ability of castor oil polymer as a root-end filling material

OBJECTIVE

The purpose of this study was to evaluate the sealing ability of castor oil polymer (COP), mineral trioxide aggregate (MTA) and glass ionomer cement (GIC) as root-end filling materials. Forty-five single-rooted human teeth were cleaned and prepared using a step-back technique. The apical third of each root was resected perpendicularly to the long axis direction. All teeth were obturated with gutta-percha and an endodontic sealer. After, a root-end cavity with 1.25-mm depth was prepared using a diamond bur. The specimens were randomly divided into three experimental groups (n=15), according to the root-end filling material used: G1) COP; G2) MTA; G3) GIC. The external surfaces of the specimens were covered with epoxy adhesive, except the root-end filling. The teeth were immersed in rhodamine B dye for 24 hours. Then, the roots were sectioned longitudinally and the linear dye penetration at the dentin/material interface was determined using a stereomicroscope. ANOVA and Tukey's tests were used to compare the three groups. The G1 group (COP) presented smaller dye penetration, statistically different than the G2 (MTA) and G3 (GIC) groups (p<0.05). No statistically significant difference in microleakage was observed between G2 and G3 groups (p>0.05). The results of this study indicate that the COP presented efficient sealing ability when used as a root-end filling material showing results significantly better than MTA and GIC.

Long-term assessment of the seal provided by root-end filling materials in large cavities through capillary flow porometry

AIM

To evaluate the long-term sealing ability of a variety of materials when used as root-end fillings.

METHODOLOGY

A total of 140 standardized horizontal bovine root sections (external diameter: 7 mm, height: 3 mm; internal diameter: 2.5 mm) were divided into seven groups, filled with either gutta-percha with AH26, Ketac Fil, Fuji IX, Tooth-Colored MTA, IRM, Ketac Fil with conditioner or Fuji IX with conditioner and submitted to capillary flow porometry at 1 and 6 months to assess minimum, mean flow and maximum pore diameters. Results of the different materials and results by material were analysed statistically using non-parametric tests; the level of significance was set at 0.05.

RESULTS

There were no significant differences between the minimum pore diameters associated with the materials at each time. At 1 month the mean flow pore diameters of Ketac Fil were significantly larger than those of gutta-percha, Ketac Fil with conditioner, Fuji IX with conditioner and IRM. There were significant differences between the maximum pore diameters at 1 month (all>IRM; Fuji IX>gutta-percha, Ketac Fil with conditioner, Fuji IX with conditioner) and 6 months (Fuji IX>gutta-percha, IRM; Ketac Fil>gutta-percha, IRM). There were significant differences in the minimum pore diameters between the different points in time for each material except IRM, in the mean flow pore diameters for each material and in the maximum pore diameters for each material except MTA.

CONCLUSIONS

All materials were associated with capillary flow. IRM root-end fillings had through pores that were smaller than those associated with other materials. Conventionally setting glass-ionomer cements had the largest pores, although dentine conditioning improved their performance. The seal of all materials improved after 6 months.

Leakage of Bovine Serum Albumin in Root Canals Obturated with Super-EBA and IRM

The aim of this study was to determine the leakage of SuperEBA and intermediate restorative material (IRM) in root canal samples, with or without orthograde filling, by evaluating bovine serum albumin (BSA) microleakage using spectrophotometry. Thirty-five single-rooted teeth were divided into five groups, instrumented, and had apices resected. Root-end cavities in groups I and II were filled with SuperEBA and IRM. The samples from the groups III, IV, and V were filled with gutta-percha and sealer. In groups IV and V, root-end cavities were filled with SuperEBA and IRM. After 60 days, the greatest microleakage of BSA was observed in group II (4.1 +/- 0.0011 ng), followed by group III (3.4 +/- 0.0064 ng), and then group I (2.6 +/- 0.0019 ng). Samples from groups IV and V leaked the least (0.7 +/- 0.0014 ng). Significantly less leakage (p < 0.05) occurred in samples filled with orthograde and root-end fillings than did in samples filled only with an orthograde approach and the samples with IRM root-end fillings.

Comparison of the Sealing of Resilon, Pro Root MTA, and Super-EBA as Root-End Filling Materials: A Bacterial Leakage Study

The purpose of this in vitro study was to compare the root-end sealing of the Resilon/Epiphany system (RES) to Pro Root MTA and Super-EBA using a bacterial leakage system. Fifty-five extracted teeth were instrumented and root-ends were resected and ultrasonically prepared. Test materials were placed in the root-end preparations; Streptococcus salivarius was introduced coronally and the apical 4 mm were immersed in BHI culture medium with phenol red indicator. Bacterial leakage was monitored every 24 h for 4 wk. All positive controls leaked within 24 h; none of the negative controls leaked. Based on chi2 analysis (p < 0.05), RES and MTA leaked significantly less than Super-EBA. There was no statistical difference between RES and MTA. RES may be a viable option as a root-end filling material with good surgical isolation.

Apical Leakage of Resin Based Root Canal Sealers with a New Computerized Fluid Filtration Meter

In this in vitro study, the apical leakage of three root-canal sealers: AH Plus, Diaket, and EndoREZ was evaluated using a new computerized fluid filtration meter. Forty-five extracted human premolar teeth with single root and canal were used. The coronal part of each tooth was removed and the root canals were prepared using GT Rotary files and crown-down technique. The roots were randomly divided into three groups of 15 samples, filled with one of the test materials and gutta-percha cones by the cold lateral condensation technique and were stored at 37 degrees C and 100% humidity for 7 days. One-week later, apical parts of roots of 10 +/- 0.05 mm were attached to computerized fluid filtration meter. Apical leakage quantity was determined as microl/cmH(2)O/min(-1). Statistical analysis indicated that root fillings with Diaket in combination with cold lateral condensation technique showed lower apical leakage than the others (p < 0.05). In addition, this new computerized fluid filtration meter allowed quantitative measurement of leakage easily. As it is a newly developed device to measure apical leakage of endodontic sealers, the reliability of it needed to be tested.

The use of glass ionomer cements in both conventional and surgical endodontics

The capacity to bond to dental tissues, especially to dentine, their long-term fluoride release and their biocompatibility make glass ionomer cements (GICs) advantageous for use in endodontics, as well as in restorative dentistry. This review provides information on the basic properties of GICs, such as adhesion, antimicrobial effects and biocompatibility, particularly as they relate to use in endodontics. Indications for the use of GICs in endodontics are orthograde root canal sealing, root-end filling, repair of perforations and root resorption defects, treatment of vertical fractures and maintenance of the coronal seal. The paper includes a review on each of these indications. It is concluded that in spite of the critical handling characteristics and the inconclusive findings regarding sealing ability and antimicrobial activity, there is substantial evidence to confirm their satisfactory clinical performance. Both soft tissue and bone compatibility make them suitable for use during endodontic surgery.

The comparative sealing ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid as root-end filling materials

A comparison was made of the ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid to prevent the leakage of bacteria from root canals, when used as root-end filling materials. The materials were tested in a double-chamber device in which a root segment connects the upper (delivery) chamber and the lower (receiving) chamber. The root segment was prepared by having the root canal instrumented to a #45 file, and a 3-mm-deep, root-end preparation placed at the apical foramen. The canal of each root segment was filled with gutta-percha, and the root-end preparation was filled with one of three test materials, mixed according to the manufacturer's directions. Negative controls were constructed with sticky wax sealing the apical foramen. A titered suspension of radioactively (3H-thymidine)-labeled bacteria (Enterococcus fecalis) was placed into the delivery chamber, and sterile saline was placed into the receiving chamber such that the apical third of each root section was immersed. At various time points, samples were taken from the receiving chamber, and measured for 3H activity. The results indicated that (a) all the test materials leaked significantly compared with the negative controls; and (b) there was no significant difference found between the leakage rates of the three materials tested.

Tissue reactions after intraosseous implantation of three retrofilling materials

Bone tissue reactions to EBA, IRM, and cyanoacrylate cement (Base Liner) were studied in the rat mandible using an intraosseous implant method. Osseous cavities (1.4 mm in diameter) were surgically created in the mandibles, and materials were implanted in 60 male Wistar rats. Each specimen was evaluated histologically after 4 and 8 weeks. The development of fibrous connective tissue in direct apposition to the material was observed in the EBA and IRM groups at 4 weeks. A slight degree of macrophage infiltration was seen in the EBA group. After the 8-week observation period, IRM and EBA were frequently separated from the bone cavity by a fibrous connective tissue layer (p < 0.01). The Base Liner appeared to be in direct apposition to the osseous tissue in several areas (p < 0.01). These findings indicate that Base Liner reacts favorably with osseous tissue, compared with the EBA and IRM materials tested and seems to be a biocompatible material.

Leakage evaluation of root end filling materials using endotoxin

Mineral trioxide aggregate (MTA) has been shown to possess excellent sealing ability when tested with dye, bacteria, and a fluid filtration technique. Endotoxin, a component of the cell wall of Gram-negative bacteria, has been proposed to play a role in the pathogenesis of periradicular lesions. This study used a modified Limulus Amebocyte Lysate test for the presence of endotoxin as a tracer and compared the sealing ability of Super-EBA, IRM, amalgam, and MTA. The results showed that MTA permitted less endotoxin leakage than IRM and amalgam at 1, 2, 6, and 12 wk (p < 0.05), and leaked less than Super-EBA at 2 and 12 wk (p < 0.05).

The quality of root fillings remaining in mandibular incisors after root-end cavity preparation

AIM

The aim of this study was to determine the quality of root fillings remaining in mandibular incisors after root-end resection and root-end cavity preparation.

METHODOLOGY

Roots of 40 mandibular incisors,12 mm in length, were divided into two groups and instrumented using a balanced force technique and obturated by vertically compacted warm gutta-percha. In one group sealer was used when back-filling the root canal with the Obtura System. The other group was also back-filled with the Obtura System but without sealer. The apical 4 mm of each root filling was removed by root-end resection and root-end cavity preparation. Fluid transport along the 7 mm of remaining root filling was measured. After the leakage test, horizontal sections were cut at a level 3 mm from the apical end of the remaining root filling. The cross sectional area of the canal and gutta-percha was measured using an image analysis program. The quality of the remaining root fillings was also evaluated by calculating the percentage of gutta-percha filled canal area.

RESULTS

In total, 27 (67%) out of the 40 roots demonstrated leakage. No significant difference was found between the two groups (P = 0.265). In the cross-sections the bucco-lingual canal diameter was up to 2.6 mm long (mean 1.6 mm). The average percentage of gutta-percha filled canal area was 85.6%. Warm gutta-percha could not obturate areas where debris remained after instrumentation.

CONCLUSIONS

The quality of the root fillings in mandibular incisors was poor, probably because the unprepared recesses of oval canals were not clean.

Application of titanium-alloy endodontic implants in conjunction with periradicular surgery

OBJECTIVE

To evaluate the outcome of placement of titanium-alloy endodontic implants in conjunction with periradicular surgery.

STUDY DESIGN

Twenty-four teeth were treated with endodontic implants with corresponding periradicular surgery by using SuperEBA cement (Harry J Bosworth Co, Skokie, Ill) as a sealer. The results of the endodontic implant surgery were evaluated clinically and radiographically from 2 to 4 years after treatment.

RESULTS

Twenty-two teeth were treated successfully, whereas 2 teeth were treated unsuccessfully, for a success rate of 92%.

CONCLUSIONS

Titanium-alloy endodontic implants in conjunction with periradicular surgery may provide good short-term results. Sealing between the endodontic implant and the dentin is likely an important factor for success.

Leakage of five root canal sealers

AIM

The aim of this study was to examine the apical sealing ability of five root canal sealers using a fluid transport model.

METHODOLOGY

A comparison of root canal scalers AH26, AH Plus, Diaket, Apexit, and Ketac-Endo were tested on 60 single-rooted teeth. The coronal part of each tooth was removed at the amelo-cemento junction, and also 3 mm of the root tip. Root canals were instrumented using the 'step-back' technique with Gates Glidden drills and irrigated with 2.5% NaOCl. The specimens were divided into five groups of 10 samples each and filled with test materials and gutta-percha points by the cold lateral condensation technique. Ten teeth were used as a control group, out of which five served as negative and five as positive controls. The leakage was measured by the movement of an air bubble in a capillary glass tube connected to the experimental root section.

RESULTS

The differences in leakage amongst Ketac-Endo (0.318 microL: SD 0.084), AH26 (0.319 microL; SD 0.075), AH Plus (0.330L; SD 0.085) Apexit (0.360 microL; SD 0.127) and Diaket (0.387 microL; SD 0.140) were not statistically significant (P > 0.05).

CONCLUSIONS

Under the conditions of this study, all five sealers produced a satisfactory seal.

Longitudinal microleakage evaluation of Super-EBA as a root-end sealing material

This study evaluated the sealing ability of fast and regular set Super-EBA with different powder-to-liquid ratios as a root-end filling material. Fifty extracted maxillary central incisors were uniformly cleaned and shaped using a crown-down technique with Gates-Glidden drills and Profile series 29.04 taper rotary instruments. After root-end resection and ultrasonic preparation, 48 root sections were randomly assigned to 4 groups of 12 teeth each and filled with a thick or thin mix of fast or regular set Super-EBA. Fast and regular set Super-EBA were mixed to a thick (1 scoop powder:1 drop liquid) or a thin (1 scoop powder:2 drops liquid) consistency. Positive and negative controls were used. Microleakage was assessed at 24 h, 72 h, 1 wk, 2 wk, 4 wk, 6 wk, and 8 wk using a fluid filtration system. There were no significant differences in the microleakage measured for any group at any of the time points evaluated. These results suggest that either fast or regular set Super-EBA mixed to various consistencies may be acceptable for root-end filling.

Considerations in the selection of a root-end filling material

Surgical root canal treatment often includes the placement of a root-end filling material. New materials have recently emerged to challenge the long-standing position of amalgam as the root-end filling material of choice. This review discusses several of the commonly used root-end filling materials, with emphasis on indications and contraindications for the use of each.

A fluid filtration and clearing technique to assess microleakage associated with three dentine bonding systems

OBJECTIVES

The aims of this in vitro study were to (a) measure fluid flow through teeth restored with one of three dentine bonding systems and a resin composite restoration; (b) measure the distribution of a silver tracer through the same teeth, and make a comparison with fluid flow; and (c) investigate the effect of thermocycling on both measurement types.

METHODS

Coronal segments of 30 premolars, randomly allocated to three equal groups, were assessed by fluid filtration. Each group was restored with a resin composite restoration in conjunction with Fuji Bond LC (FBLC), Scotchbond Multi-Purpose Plus (SMP+) or Prime&Bond 2.1 (P&B2.1). Fluid filtration rates were measured in the intact crown and then after cavity preparation, conditioning, dentine bonding, restoration and at 2 and 24 h, 1 week and 1 month following restoration. Six specimens from each group were thermocycled at 1 week. After final filtration measurements the specimens were perfused with silver nitrate and cleared before scoring tracer penetration.

RESULTS

No significant differences (P > 0.05) in fluid filtration rates were found amongst the different bonding systems or at any restoration stage. Thermocycling was not associated with any significant (P > 0.05) increase in fluid filtration. Final fluid filtration and tracer distribution showed a weak and not statistically significant correlation (P > 0.05). The penetration of silver stain indicated a failure of the restorations to seal the cavity and demonstrated a possible pathway by which in vivo post-operative sensitivity could occur.

CONCLUSIONS

Although not statistically significant, conditioning of the cavity increased the dentinal permeability but this effect was variable. Thermocycling had no statistically significant effect on microleakage.

Microleakage of super-EBA with and without finishing as determined by the fluid filtration method

Super-EBA (SEBA) has been used as a root-end filling material because of its superior sealing properties and clinical success. The purpose of this study was to evaluate whether finishing SEBA after it had set would affect the apical seal. Sixty-five extracted maxillary anterior teeth were instrumented and obturated with a single gutta-percha master cone. The root end was resected, and a 3 mm deep root-end preparation was made using ultrasonic tips. Teeth were randomly divided into three groups. Group 1 received SEBA and was finished with a 30-flute high-speed finishing bur. Group 2 received SEBA, which was cold-burnished with a ball burnisher. Temporary Endodontic Restorative Material was used as the negative control in group 3. Microleakage (microliter/min) was measured under 10 psi using the fluid filtration method at days 1, 7, 30, 90, and 180. SEBA/finished exhibited significant microleakage at day 1 when compared with the burnished group. The differences in leakage were not significant at any other time period.

Longitudinal study of the microleakage of two root-end filling materials using a fluid conductive system

A comparison of the microleakage of mineral trioxide aggregate (MTA) and a high copper admix amalgam (Valiant PhD) in root-end preparations was made using a fluid conductive device. Thirty-three bilaterally matched pairs of extracted, single-rooted teeth were prepared and obturated using lateral compaction of gutta-percha. The root-ends were resected and 3-mm-deep class I cavity preparations were made. The root-end preparations were filled with either amalgam or MTA. Guttapercha coronal to the root-end fillings was removed leaving only the amalgam or MTA present as a barrier to fluid movement. In the fluid-conductive device, the root canals were filled with a phosphate-buffered saline solution at a pressure of 10 psi. The flow of fluid was measured and compared at 1, 2, 3, 4, 8, 12, 16, 20, and 24 wk. The results showed amalgam to have significantly higher microleakage after 4 wk and higher variability compared with the MTA group.

Long-term seal provided by some root-end filling materials

A tight and long-lasting seal of root-end fillings is of prime clinical importance. A hundred standard bovine root sections, each 3 mm high and with a central pulp lumen of 2.6 mm in diameter, were filled with five commonly used or potential root-end filling materials. At 24 h, or at 3, 6, or 12 months after filling, leakage along these filling materials was determined under a low headspace pressure of 10 kPa (0.1 atm) using a fluid transport model. During the first 3 months, the percentage of gross leakage (> 20 microliters day-1) increased noticeably for Tytin amalgam (from 20 to 100%) and Super-EBA (from 0 to 55%), whereas it decreased noticeably for mineral trioxide aggregate (MTA; from 55% to 0%). Thereafter, the increased leakage of amalgam and Super-EBA decreased with time, whereas the improved seal of MTA was maintained until the end of the experiment. At 3-, 6-, and 12-month time intervals, both glass ionomer cements (Fuji II and Hi Dense) and MTA showed less leakage than the conventional amalgam and Super-Eba, of which amalgam leaked more.

Scanning electron microscopic evaluation of finishing techniques on IRM and EBA retrofillings

Various techniques have been advocated for finishing retrofilling materials. This study evaluated marginal interfaces between tooth structure and the retrofilling material following three techniques of finishing IRM and EBA. This interface was evaluated for the presence of flash and for adaptation to the prepared canal walls. Thirty-one teeth were divided into six groups of five and one control. The teeth were instrumented to a minimum of a 35 K-file, obturated with gutta-percha, resected perpendicular to their long axes and ultrasonically prepared to receive a retrofilling. The teeth were filled with either IRM or EBA cement and finished by ball burnishing, burnishing with a moistened cotton pellet, or with a carbide finishing bur in a high-speed handpiece with air/water spray. Photomicrographs were made and examined by four evaluators. Retrofillings finished with a finishing bur displayed significantly better marginal adaptation and little evidence of flash when compared to the other techniques (p < 0.05). There were no significant differences between ball burnished or moistened cotton pellet techniques or between retrofilling materials used in this study (p < 0.05).

Longitudinal sealing ability of mineral trioxide aggregate as a root-end filling material

This study evaluated the ability of mineral trioxide aggregate (MTA) to seal the root end effectively. Seventy-six single-rooted, extracted human teeth were cleaned and shaped using a step-back technique. After root-end resection and ultrasonic preparation, 72 root sections were randomly allocated to three groups and filled with dental amalgam and cavity liner, Super-EBA, or MTA. Microleakage was assessed at 24 h, 72 h, 2 wk, 4 wk, 8 wk, and 12 wk, using a fluid filtration measurement system. MTA demonstrated excellent sealing ability throughout 12 wk of fluid immersion, comparable with that observed for Super-EBA. Microleakage in the MTA group, as well as the Super-EBA group, was significantly less (p < 0.05) than in the amalgam group at 24 h, 72 h, and 2 wk. At the subsequent periods, there were no significant differences among the three materials. In this study, MTA was determined to be superior to amalgam, and comparable with Super-EBA in preventing microleakage when used as a root-end filling.

Root end filling materials: a review

When non-surgical attempts prove unsuccessful or are contraindicated, surgical endodontic therapy is needed to save the tooth. The procedure usually consists of exposure of the involved area, root end resection, root end preparation and insertion of a root end filling material. Numerous materials have been suggested as root end filling materials. This article is a review of the literature on the suitability of various root end filling materials based on their leakage assessment, marginal adaptation, cytotoxicity, and usage test in experimental animals and humans.

Effect of various zinc oxide materials as root-end fillings on healing after replantation

This study examined the effect of various zinc oxide materials as root-end fillings of teeth in a replantation model. A total of 35 molar teeth were used from 19 monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root-end cavities prepared and fillings placed prior to replantation. After 8 weeks the teeth and surrounding jaw were removed and prepared for histological examination. Twelve roots were filled with IRM plus dentine chips, and six with Cavit; the tissue response around root ends filled with these materials as assessed by inflammation was similar to that previous reported to IRM and Super EBA cement and was characterized by little or no inflammation of limited extent. In contrast, more severe inflammation was observed around root ends filled with plain zinc oxide-eugenol or Kalzinol; however, the reaction was neither as severe nor as extensive as that to amalgam root-end fillings. Giant cells were observed most often on the surface of fillings with Cavit and zinc oxide-eugenol. It is concluded that the tissue response to IRM with or without added dentine, Super EBA and Cavit was similar and mild; it was less severe than that to zinc oxide-eugenol and Kalzinol. All these materials had a much more favourable response than amalgam

Evaluation of the seal of various amalgam products used as root-end fillings

Different formulations of amalgam have physical properties that may make them behave differently in the often-contaminated root end environment. Five different brands of amalgam were evaluated for microleakage of root-end fillings placed in extracted human teeth. These included a zinc-free spherical amalgam, a zinc-free admixture amalgam, two zinc-containing admixture amalgams, and a zinc-containing lathe-cut amalgam. The amalgams were placed either into dry root-end preparations or into preparations contaminated with human blood. The fluid filtration method was used to measure microleakage at 1, 2, 4, 8, 12, and 24 wk after placement. Analysis of variance revealed significant differences in the rates of microleakage at every measurement period. Scheffé's test showed that the zinc-free spherical amalgam had significantly greater leakage than all the other products evaluated. There were no significant differences between any of the other products. Blood contamination did not adversely affect the seal of any amalgam.

Longitudinal evaluation of the microleakage of dentin bonding agents used to seal resected root apices

A material that bonds to dentin and seals both the root canal and exposed dentinal tubules would be desirable following root resection. The purpose of this study was to measure the sealing ability of four dentin bonding agents on the resected root end. The bonding systems evaluated were Amalgambond (AMB), Scotchbond Multi-Purpose (SMP), Prisma Universal Bond 3 (PUB 3), and All-Bond 2 (AB2). All materials were applied directly to the resected root end without a class I preparation. One-half of the roots in each group were contaminated with human blood before bonding. Microleakage was measured using fluid filtration at various time intervals from 1 to 24 wk. Results indicated that all dentin bonding agents significantly reduced apical microleakage compared with prebonded controls at all time intervals. Blood contamination did not adversely affect the sealing ability of AMB, PUB 3, or SMP. The blood-contaminated AB2 group displayed significantly greater microleakage after 12 and 24 wk than the uncontaminated roots.

A 1-year follow-up study on leakage of four root canal sealers at different thicknesses

Determination of leakage using a fluid transport model allows measurement of leakage in a longitudinal manner. Leakage of four sealers at three different thicknesses in 225 bovine root sections, after storage in water for 1 year, was measured again using the same methodology. The change in seal over time for each sealer was observed. The results after the second measurement showed that every sealer produced the best seal when the sealer layer was the thinnest. AH26, Ketac-Endo and Tubli-Seal showed a reduction in leakage over time and gave significantly less leakage than Sealapex (P<0.005). Sealapex showed significantly more leakage after storing in water for 1 year (P<0.005). Therefore, the long-lasting seal of sealer may, among other influencing factors, depend on the layer thickness and the solubility of the material.

The effect of retrograde cavity design on microleakage of amalgam fillings

A phantom head model was modified to simulate as closely as possible the limited access encountered during periapical surgery on maxillary anterior teeth. Extracted human maxillary anterior and mandibular canine teeth were placed in this model in a standardized position for root resection, retrograde cavity preparation and filling with amalgam. Three different designs of retrograde cavities were evaluated: the conventional class 1 cavity, the slot cavity and a previously unreported approach, the funnel cavity. Upon completion of the retrograde filling, the teeth were removed from the model and subjected to microleakage tests by placing radiolabelled lipopolysaccharide in a reservoir created coronal to the retrograde fillings. Leakage was quantified by measurement of radioactivity in scintillation counter. It was found that the retrograde fillings in the funnel cavity leaked significantly less than those in the other two cavity designs. There was no statistically significant difference in leakage between the conventional class 1 and the slot cavities up to the thirtieth day 30.

Comparative investigation of marginal adaptation of mineral trioxide aggregate and other commonly used root-end filling materials

This study investigated the marginal adaptation of mineral trioxide aggregate (MTA) as a root-end filling material, compared with commonly used root-end filling materials by scanning electron microscopy (SEM). Eighty-eight single-rooted freshly extracted human teeth were cleaned, shaped, and obturated with gutta-percha and root canal sealer. Following root-end resection and cavity preparation, the root-end cavities were filled with amalgam, Super-EBA, Intermediate Restorative Material (IRM), or MTA. Using a slow-speed diamond saw, 40 roots were longitudinally sectioned into two halves. Resin replicas of resected root ends of the remaining nonsectioned roots were also prepared. After mounting longitudinal sections of roots and resin replicas of resected roots on aluminum stubs, the distance between the test root-end filling materials and surrounding dentin was measured at four points under SEM. Examination of the original samples showed numerous artifacts in the longitudinal sections of the specimens. In contrast, the resin replicas of resected and filled root ends had no artifacts. Statistical analysis of data comparing gap sizes between the root-end filling materials and their surrounding dentin shows that MTA had better adaptation compared with amalgam, Super-EBA, and IRM.

Bacterial leakage of mineral trioxide aggregate as a root-end filling material

Previous dye leakage studies have shown that mineral trioxide aggregate leaks significantly less than other commonly used root-end filling materials. This study determined the time needed for Staphylococcus epidermidis to penetrate a 3-mm thickness of amalgam, Super-EBA, Intermediate Restorative Material (IRM), or mineral trioxide aggregate (MTA) as root-end filling materials. Fifty-six single-rooted extracted human teeth were cleaned and shaped using a step-back technique. Following root-end resection, 48 root-end cavities were filled with amalgam, Super-EBA, IRM, or MTA. Four root-end cavities were filled with thermoplasticized gutta-percha without a root canal sealer (+ control), and another four were filled with sticky wax covered with two layers of nail polish (- control). After attaching the teeth to plastic caps of 12-ml plastic vials and placing the root ends into phenol red broth, the set-ups were sterilized overnight with ethylene dioxide gas. A tenth of a microliter of broth containing S. epidermidis was placed into the root canal of 46 teeth (40 experimental, 3 positive, and 3 negative control groups). In addition, the root canals of two teeth with test root-end filling materials and one tooth from the positive and negative control groups were filled with sterile saline. The number of days required for the test bacteria to penetrate various root-end filling materials was determined. Most samples whose apical 3 mm were filled with amalgam, Super-EBA, or IRM began leaking at 6 to 57 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Leakage of amalgam and Super-EBA root-end fillings using two preparation techniques and surgical microscopy

An in vitro dye leakage study was conducted to test the root-end sealing ability of amalgam with varnish or Super-EBA using two root-end preparation techniques and surgical microscopy. Sixty-four single-rooted teeth were instrumented and obturated with gutta-percha. Teeth were randomly placed into four groups. Two groups received perpendicular root-end resections, 3-mm-deep ultrasonic root-end preparations, and either amalgam with varnish or Super-EBA root-end fillings. The other two groups received beveled root-end resections, 3-mm-deep micro-handpiece preparations, and either amalgam with varnish or Super-EBA. All root-end procedures were performed at x5 to x8 magnification. Micro-leakage was assessed at 4 months using methylene blue dye and a passive hydrostatic pressure technique. Statistical analysis showed that, regardless of technique, Super-EBA leaked significantly less than amalgam with varnish. There was no significant difference between the two root-end resection and preparation techniques.

Effect of super-EBA as a root end filling on healing after replantation

The effect of Super-EBA cement as a root-end filling placed in teeth before replantation was examined in eight molar roots in monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root-end cavities prepared, and fillings of Super-EBA placed before replantation. After 8 wk, the jaws were removed and prepared for histological examination. The tissue response to Super-EBA was very mild, with only a few inflammatory cells being observed at the root end of 3 of the 8 roots filled. Previous work showed a similarly mild response to Intermediate Restorative Material and a very much more severe response to amalgam. It is concluded that the tissue response to Super-EBA as a root-end filling is acceptable and considerably more favorable than that to amalgam.

Evaluation of an apatite cement as a root end filling material

A self-setting apatite cement, EBA cement, and amalgam with varnish were tested for root end sealing ability using a fluid filtration and dye technique. Single-rooted human teeth were prepared in vitro to receive root end fillings. Experimental groups were amalgam with two layers of varnish, EBA cement with dry cavity, EBA cement within a wet cavity, apatite cement within a dry cavity, and apatite cement within a wet cavity. Fluid filtration measurements were made at 6, 24, and 7 days, and 1 and 3 months. Each specimen was also subjected to a dye leakage test using Procion Green dye at 3 months. Results indicated that apatite cement provided a comparable seal to amalgam and EBA cement. This finding, in conjunction with its excellent biocompatibility, suggests that apatite cement is an acceptable alternative to present-day root end filling materials.

Testing of sealing ability of endodontic filling materials

Incomplete obturation of the root canal system is the major cause of endodontic failure. Endodontic filling materials with ability to seal the root canal are, therefore, essential for successful endodontic therapy. However, assessment of sealing ability is not included in the requirements specified in the current international standard covering root canal sealers. A number of different in vitro methods have been used to evaluate the sealing quality of endodontic filling materials. The tests have usually been leakage tests, i.e. based on assessment of penetration of a tracer along the obturated root canal. Leakage tests have poor reproducibility and are, therefore, not suited for standardized test programs. By selecting the properties necessary for sealing ability and testing them separately, it might be possible to find a number of tests, which individually are suitable for a standardized test program, and which combined will give information on the sealing ability of the test material.

Microleakage of retrograde root fillings: assessment using a novel measurement system

In the past, measurement of microleakage has been based on measurement of dye or radioactive isotope penetration. A method has been developed to allow electronic monitoring of microflow in the same specimen over a period of time. This method was used to compare previously reported retrograde materials with an amalgam/sealer combination. The material that performed best was amalgam/sealer, particularly in the first week. The role of cavity varnish in limiting leakage has been controversial, and the results in the present study do not indicate any significant benefit. The range of leakage measured for specimens in the same group suggests that in vivo the expected leakage could be considerable for the materials tested and that small differences in experimental leakage between groups may not have any practical significance.

Ultrasonic root-end preparation, Part 2. Microleakage of EBA root-end fillings

The effect of three methods of root-end preparation, following apical resection, on the apical seal of root-end fillings, was studied in vitro. Root canals of 116 single-rooted teeth with mature apices were prepared chemomechanically and obturated with gutta-percha and sealer. The root ends were resected with a diamond bur under water coolant and were prepared as follows: group I a size 010 round bur was used to prepare an apical cavity 2-3 mm down the long axis of the root; group II treatment as per group 1 followed by a 60-s rinse with a solution of 10:3 (10% citric acid: 3% Fe2Cl3); and group III an ultrasonic retrotip was used to prepare a 2-3 mm deep apical cavity. The root end was restored with an EBA cement. Apical leakage was determined using India ink after 7 days and 7 months. The teeth were demineralized, rendered transparent and linear dye penetration was recorded. Results showed that there was no significant difference in leakage between the groups at each time interval (P > 0.05) but there was increased leakage after 7 months (P < 0.01). Cracking of the root surface was seen most often with the ultrasonically prepared roots (P < 0.001).

Fluid transport and dye penetration along root canal fillings

Dye penetration along root canal fillings may be hindered by the presence of entrapped air. In this study, the sensitivity of a dye penetration method was compared with that of a fluid transport model. Sixty root sections from human maxillary central incisors were prepared and obturated by a modified technique to ensure a slight amount of leakage, and divided into three equal groups. Twenty root sections were first mounted in a fluid transport device and assessed for fluid transport under 10 kPa (0.1 atm.) pressure. Another 20 root sections were mounted in the same device before being subjected to air transport under the same pressure. The remaining 20 root sections were not exposed to fluid or air transport. Then, all the 60 root sections were assessed for penetration of a 2% methylene blue solution. The results showed that fluid transport was a much more sensitive method of detecting voids along root canal fillings than dye penetration. After fluid transport for 3 h under low pressure, to eliminate entrapped air, dye penetrated significantly deeper than without previous fluid transport, which suggested that entrapped air in voids along the root canal filling prevented dye penetration.

The effect of storage time on the degree of dye leakage of root-end filling materials

The quality of the apical seal obtained by root-end filling materials generally has been assessed by the extent of dye penetration. Most investigators have allowed the root-end filling materials to set before they are tested. The purpose of this study was to evaluate if storage time had any influence on the amount of dye leakage. Seventy extracted single rooted human anterior teeth were used. After removal of their anatomical crowns, the roots were instrumented, filled with gutta-percha and Roth's sealer, and subjected to test conditions. The roots were coated with two coats of nail polish. Root ends were resected and class I cavities prepared. Sixty class I root-end cavities were filled with with either amalgam, super EBA, or IRM (20 each). Ten roots in each group were placed immediately into India ink for 48 h, the other 10 were stored for 24 h before placement into the ink. Ten roots (five per group) were used as positive (gutta-percha, no sealer) and negative (bone wax) controls. The roots were then demineralized, linear dye leakage was measured, and the data were evaluated statistically using ANOVA. Super EBA, and IRM showed significantly less dye leakage than amalgam (P < 0.0001). No significant difference existed between Super EBA and IRM. Storage time had no significant influence on the amount of dye leakage observed in this study.