Microleakage of composite crowns luted on CAD/CAM-milled human molars: a new method for standardized in vitro tests

OBJECTIVES

To investigate debonding of full crowns made of CAD/CAM composites, CAD/CAM technology was applied to manufacture standardized test abutments to increase the reproducibility of human teeth used in in vitro studies.

MATERIALS AND METHODS

A virtual test abutment and the corresponding virtual crown were designed and two STL data sets were generated. Sixty-four human third molars and CAD/CAM blocks were milled using a CNC machine. Crowns of four different composite blocks (Lava Ultimate (LU), Brilliant Crios (BC), Cerasmart (CS), Experimental (EX)) were adhesively bonded with their corresponding luting system (LU: Scotchbond Universal/RelyX Ultimate; BC: One Coat 7 Universal/DuoCem; CS: G-PremioBond/G-Cem LinkForce; EX: Experimental-Bond/Experimental-Luting-Cement). Half of the specimens were chemical-cured (CC) and the others were light-cured (LC). Afterwards, specimens were artificially aged in a chewing simulator (WL-tec, 1 million cycles, 50-500 N, 2 Hz, 37 °C). Finally, a dye penetration test was used to detect debonding. For inspection, the specimens were sliced, and penetration depth was measured with a digital microscope. Data were analyzed with the Mann-Whitney U test.

RESULTS

No cases of total debonding were observed after cyclic loading. However, the LC specimens showed a significantly lower amount of leakage than the CC ones (p < 0.05). Furthermore, the CC specimens exhibited broad scattering. Only the LC-EX blocks showed no debonding. The CC-CS blocks showed the highest leakage and scattering of all tested specimens.

CONCLUSIONS

Natural human teeth can be manufactured by CAD/CAM technology in highly standardized test abutments for in vitro testing. For CAD/CAM composites, light curing should be performed.

CLINICAL RELEVANCE

The success of a restoration depends on the long-term sealing ability of the luting materials, which avoids debonding along with microleakage. For CAD/CAM composites, separate light curing of the adhesive and luting composite is highly recommended.

Influence of Iatrogenic Gaps, Cement Type, and Time on Microleakage of Cast Posts Using Spectrophotometer and Glucose Filtration Measurements

PURPOSE

To determine the influence of iatrogenic gaps, type of cement, and time on microleakage of cast posts using spectrophotometer and glucose filtration measurements.

MATERIALS AND METHODS

Forty-eight single-rooted teeth were divided into eight groups of six teeth each. Teeth were instrumented and obturated, and a cast post was fabricated. In addition to two control groups (positive and negative), a total of six groups were prepared: In four groups, an artificial 2- to 3-mm gap was created between post and residual gutta percha (GP), and two groups were prepared with intimate contact between post and residual GP. Posts were cemented with either zinc phosphate cement or resin cement. Leakage through the post after 1, 8, 14, and 20 days was measured using a glucose penetration model with two different reading methods. Mixed analysis of variance tests were performed to analyze the data.

RESULTS

The presence of a gap between the apical end of the post and the most coronal portion of the GP remaining in the root canal after post space preparation increased microleakage significantly. However, microleakage was significantly less when the gap was refilled with GP compared to no gap. There was no difference in leakage between luting cements used.

CONCLUSION

It was concluded that none of the cements were able to prevent microleakage. However, the addition of GP to residual GP did increase the sealing ability.

[The influence of the different polishing methods on the marginal sealing property of the computer aided design and computer aided manufacture zirconium dioxide full crown]

OBJECTIVE

To evaluate the influence of different polishing methods on marginal microleakage of zirconium dioxide full crown.

METHODS

Thirty extracted premolars were selected and randomly divided into three groups, A, B and C, with 10 in each group. Group A was prepared with MANI TF-13 bur completely without the treatment of shoulder. The shoulder of group B was polished with MANI TR13-EF bur after the preparation using MANI TF-13. The shoulder of group C was polished with the dental pneumatic ultrasonic hand-piece of KaVo SONICflex after the preparation using MANI TF-13 bur. Five specimens after preparation were selected in each group. Fifteen CAD/CAM zirconium dioxide full crowns have been made. The crowns were bonded using PULPDENT resin cement, and the root canals were sealed using nail polish, and apical foramen were closed using flow resin. The test-pieces have been immersed in a 3% solution of methylene blue for 24 h. The condition of shoulder marginal microleakage was observed using light stereomicroscopy and evaluated in classification index. The remaining specimens in each group were used for roughness test and scanning electron microscope(SEM) experiment. The marginal microleakage situations of specimens in three groups was analyzed by SPSS 17.0. The enamel surface of different polishing methods was observed using SEM.

RESULTS

The specimens in group C demonstrated the least marginal microleakage, and those in group B showed an intermediate level of marginal microleakage, and those in group A characterized the most serious marginal microleakage (total, χ2=44.610, P<0.01; among the different groups, P<0.05). The roughness experiment showed that specimens in group C achieve the smoothest results ([0.27±0.03] μm). Preparation shoulder polished using the dental pneumatic ultrasonic hand-piece demonstrated the best result under the SEM among the three groups.

CONCLUSIONS

The anti-microleakage effectiveness of dental pneumatic ultrasonic hand-piece in shoulder refinement is better than ordinary shoulder treatment.

Evaluation of UCLA implant-abutment sealing

PURPOSE

To evaluate the effect of the presence of a prefabricated cobalt-chromium (CoCr) margin in a universal castable long abutment (UCLA) on the sealing capability and fit of the implant-abutment interface.

MATERIALS AND METHODS

One-hundred twenty external hexagon implants (SIN) were divided into two groups (n=60 each) to receive UCLA abutments from six manufacturers (n=10 each) either with or without a CoCr margin (n=60 each). Abutments were cast and 12 groups were formed: M (Microplant), I (Impladen), S (SIN), Sv (Signo Vinces), T (TitaniumFix), and B (Bionnovation). Sealing was determined by placing 0.7 µL of 0.1% toluidine blue in the implant wells before abutment torquing. Implant-abutment samples were placed into 2.0-mL vials containing 0.7 mL of distilled water to maintain the implant-abutment interface, and aliquots of 100 µL of water were retrieved at 1, 3, 6, 24, 48, 72, 96, and 144 hour incubation times for measurement of absorbance in a spectrophotometer, and returned for repeated measurements. Two-way ANOVA (P<.05) and Tukey's test were used. Scanning electron microscopy (SEM) was used for observation of the implant-abutment fit.

RESULTS

Groups M, Sv, and T without the CoCr margin resulted in complete release of toluidine blue at 1 hour, whereas I, S, and B did so at 3, 24, and 96 hours, respectively. Complete leakage in abutments with the prefabricated margin occurred at 6 hours for S; 24 hours for Sv, T, and B; and 72 hours for M and I. Implant-abutment gaps were observed in all groups. A poorer fit was depicted for groups M and T without the CoCr margin.

CONCLUSION

Complete leakage was observed for all UCLA abutments regardless of the presence of the CoCr margin. Implant-abutment gaps were observed in all groups.

[Comparison of leakage at the implant to abutment connection in several implants types using a gas flow method]

INTRODUCTION

The aim of this study was to compare the leakage at the implant to abutment connection in several implants, using a new gas diffusion method.

MATERIAL AND METHODS

Sixty-eight implants of 13 different types were used. Nitrogen leaking was measured after screwing the connections to the torque levels recommended by the manufacturers.

RESULTS

A significant tightness difference was observed between the different implant types. This difference cannot be explained by the various connection designs (flat, conical) or by the various torques recommended by the manufacturers.

CONCLUSION

The authors suggest that the tightness difference between the various implant systems could be mainly associated with quality and precision of machining.

Influence of methodologic aspects on the results of implant-abutment interface microleakage tests: a critical review of in vitro studies

PURPOSE

This study sought to evaluate the influence of methodologic aspects on variations in the findings of in vitro microleakage studies of the implant-abutment interface.

MATERIALS AND METHODS

The MEDLINE, EMBASE, and Cochrane Library databases were consulted for in vitro studies published between 1990 and August 2011. Date from the studies that met the inclusion and exclusion criteria were arranged in tables and subjected to descriptive analysis.

RESULTS

Twenty-one studies were found to be eligible for the analysis after application of the inclusion/exclusion criteria. Sixteen studies used bacteria (76.2%), one used a bacterial toxin (4.76%), one used saliva (4.76%), two employed dyes (9.52%), and one used a combination of dyes and bacteria (4.76%). Eight studies evaluated microleakage from the inner portion of the implant to the external portion (38.1%) and nine examined the reverse (42.85%), while four studies investigated the relationship between them (19.05%). The volume inoculated inside the implants ranged from 0.1 to 5.0 mL. The bacterial concentrations used in the tests ranged from 2.41 x 10⁶ to 8 x 10⁸ colony-forming units/mL. Oral bacterial flora; mixtures of bacteria, toluidine blue, and gentian violet; and lipopolysaccharide of Salmonella enterica bacterial toxins were used. The monitoring period of test results ranged from 24 hours to 11 weeks for bacteria, 5 minutes to 7 days for dye, and 7 days for bacterial toxins. In four studies, microleakage was correlated with the size of the implant-abutment microgap. The external-hexagon implant configuration showed the greatest microleakage, followed by internal-trilobe, internal-hexagon, and internal-taper configurations.

CONCLUSION

The lack of standardization hinderd comparisons of the studies and could explain the divergent results. It is suggested for future studies that special emphasis be placed upon inoculation and analysis of the specific volume for each system, lower concentrations of inoculated bacterial suspensions, and shorter follow-up time when using bacteria.

An in vitro study to assess glucose microleakage along fiber posts cemented with 2- and 3-step etch-and-rinse resin adhesive systems

The aim of the study is to compare the sealing ability of two adhesive systems. Thirty teeth were endodontically treated and were randomly assigned to 2 groups: G 1 - 3-step adhesive (Solobond-Plus) and G 2 - 2-step adhesive (Solobond-M). Posts containing glass fiber were cemented using the adhesive technique recommended by the manufacturer. All samples were mounted on a glucose leakage model. A 10 microL aliquot of solution was drawn from the glass bottle using a micropipette. The samples were then analyzed in a UV-Vis spectrophotometer. The two tested adhesive systems presented a similar capacity to prevent the glucose infiltration.

Nanoleakage of current self-etch adhesives bonded to artificial carious dentin

PURPOSE

To evaluate the nanoleakage of one- and two-step self-etch adhesives bonded to artificial carious dentin.

METHODS

Deep dentin of 24 human molars was exposed and divided into four groups. One group served as control while the others were demineralized in artificial demineralization solution for 10 minutes, 6 hours, and 24 hours. Roots were sectioned and the crowns were bonded with one- and two-step self-etch adhesives (Clearfil S3 and Clearfil SE Bond) then restored with flowable composite (Estelite Flow Quick). Specimens were exposed to intrapulpal pressure through a tube connected to a barrel filled with silver nitrate solution in total darkness for 24 hours and then sectioned into two mid-slabs that were photo-developed and prepared for nanoleakage evaluation using FE-SEM and EDX. Penetration of silver into the hybrid and adhesive layers was evaluated and compared between adhesives and dentin condition. Data were statistically analyzed by Kruskal-Wallis test (alpha = .05).

RESULTS

Increasing depths of demineralization were observed with increasing demineralization time. There were statistically significant differences for both adhesives (P < 0.05) and dentin demineralization (P< 0.05) in hybrid and adhesive layers. Normal dentin interfaces revealed no or slight nanoleakage regardless of adhesive. The bonded interface treated with one-step Clearfil S3 showed significant differences between normal and demineralized dentin. Also a trend towards increases in nanoleakage with the increasing of the demineralization time was demonstrated. Different patterns of nanoleakage were observed within adhesives.

In vitro comparison of three materials as apical sealants of equine premolar and molar teeth

REASONS FOR PERFORMING STUDY

Surgical endodontic therapy is a conservative dental technique used in horses with some degree of clinical success. Failure of this procedure can partially be explained by inadequate sealing of the root apices with resultant microleakage in the periapical area.

OBJECTIVES

To assess and compare in vitro sealing ability of 3 different dental restorative materials used as apical sealants during equine surgical endodontics.

METHODS

Thirty extracted equine cheek teeth were divided randomly into 3 groups and subjected to apicoectomy and apical sealing using 3 materials: reinforced zinc oxide-eugenol cement; intermediate restorative material (IRM); a resin-modified glass ionomer; and amalgam. After apical sealing, the teeth were submerged in a solution of Procion Brilliant Cresyl Blue stain for a period of 7 days. The teeth were then washed, embedded in resin, sectioned and assessed microscopically for dye leakage around the apical restorations.

RESULTS

Although the materials proved effective as apical sealants, some dye leakage was encountered in all 3 groups with no statistical difference (P = 0.114).

CONCLUSIONS AND POTENTIAL RELEVANCE

IRM, a resin-modified glass ionomer and amalgam all showed comparative features as apical sealants when used in vitro in equine teeth. IRM is currently regarded as the superior material in clinical situations due to its ease of handling and lesser sensitivity to environmental moisture during placement compared to the other 2 materials.

Cross-sectional assessment of apical dye penetration following three endodontic obturation techniques

This study sought to investigate apical leakage following three endodontic obturation techniques. Fifty-one recently extracted maxillary and mandibular canines were decoronated at the cementoenamel junction (CEJ) level and a size 10 file was passed to the exit of the apical foramen. Working distance was established 0.5 mm from where the file could be seen exiting the apical foramen. All teeth were instrumented using Brasseler Sequence files to a .06 taper size 40 file at working distance. The teeth were randomly divided into three groups: Group A (lateral condensation of gutta-percha with Roth's 811 Elite sealer), Group B (gutta-percha with GuttaFlow sealer), and Group C (Activ GP gutta-percha cone with Activ GP glass ionomer sealer). Two groups of three teeth served as positive and negative controls. There were no significant differences between Groups A and B; however, Group C was significantly different from Groups A and B.

Cervical microleakage in Class II cavities restored with the Sonicsys approx system

OBJECTIVE

To investigate the cervical microleakage in Class II cavities restored with Sonicsys approx ceramic inserts and four resin-based materials.

METHOD AND MATERIALS

Forty noncarious and crack-free mandibular third molars were used. These teeth were randomly assigned to four groups each containing 10 teeth. No control group was created. On each tooth, one mesial boxlike cavity was prepared using the active head Sonicsys approx no. 3. The cervical margin of each cavity was in enamel about 1 mm coronal to the cementoenamel junction. According to manufacturer's instructions, the prepared cavities were restored using a Sonicsys approx ceramic inserts no.3 and four resin-based materials as follows: group 1, Tetric Flow; group 2, Admira Flow; group 3, Nexus 2; group 4, X-Flow. After finishing and polishing, all specimens were stored in distilled water for 7 days at 37 degrees C, thermocycled 1,000 cycles between 5 degrees and 55 degrees C, and stored for 24 hours in basic fuchsine 2%. All specimens were then embedded in clear acrylic resin and sectioned along a mesial-distal plane through the middle of the cervical margin. The cervical areas of the resulting sections were examined using an optical microscope to assess the dye penetration. The registered scores were analyzed using Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

Microleakage was detected in each experimental group. Kruskal-Wallis test revealed statistically significant differences among groups (P = .009, alpha = .01). The Mann-Whitney U test showed significant differences between Admira Flow group and Tetric Flow (P = .011, alpha = .05), Nexus 2 (P = .001, alpha = .01), and X-Flow (P = .004, alpha = .01), respectively.

CONCLUSION

Within the limitations of this study, the extent of microleakage in the cervical area (enamel) of Class II cavities restored with Sonicsys approx ceramic inserts depends on the material used for luting. The highest leakage occurred when Admira flow was used.

In vitro enamel sealing of self-etch adhesives

OBJECTIVE

The use of self-etch adhesives has increased in spite of reports of deficient enamel bonding. Some clinicians etch enamel separately to circumvent this shortfall. Therefore, the objective of this study was to assess the influence of acid-etching on the enamel sealing of 3 self-etch adhesives after thermal fatigue.

METHOD AND MATERIALS

Two box-type preparations were restored in each of 30 bovine incisors with 1 of 3 self-etch adhesives: Adper Prompt L-Pop (3M ESPE); Clearfil SE Bond (Kuraray America); or iBond (Heraeus Kulzer), with and without phosphoric acid enamel etching, followed by Filtek Z250 (3M ESPE). After half of the restorations were fatigued for 1,500 thermal cycles, marginal sealing was challenged with 50% ammoniacal silver nitrate. Silver penetration was ranked from 0 to 4 and interfaces analyzed under a field-emission scanning electron microscope (FESEM) with a backscattered detector. Nonparametric statistical analyses were carried out at a 95% confidence level.

RESULTS

Clearfil SE Bond resulted in significantly less enamel leakage than the other 2 self-etch adhesives. Acid etching significantly reduced silver infiltration for all adhesives when specimens were thermocycled. When specimens were not thermocycled, acid etching only reduced silver infiltration for iBond. Under the FESEM, silver deposition was observed inside the adhesive layer for Adper Prompt L-Pop and iBond. For Clearfil SE Bond only 2 of 10 specimens displayed silver infiltration along the enamel-adhesive interface.

CONCLUSION

Etching with phosphoric acid improved the enamel marginal sealing of the 3 self-etch adhesives when specimens were subjected to thermal fatigue.

Microleakage of Class II restorations with different tracers--comparison with SEM quantitative analysis

PURPOSE

(1) To compare SEM quantitative marginal analysis data with the depth of penetration (DP) of the three most commonly used tracers for microleakage in Class II fillings in vitro; (2) based on the obtained results to calculate the discriminatory power of a sample size of 12.

MATERIALS AND METHODS

Standardized large cavities (mesially 1 mm above the CEJ, distally 1 mm below the CEJ, intercuspal distance 70%) were prepared into 36 extracted caries-free first mandibular molars and filled with Tetric EvoCeram/AdheSE, the resin being applied in horizontal layers 2 mm thick. Each increment was light cured for 20 s (1200 mW/cm2). Finishing was performed with fine diamond burs and disks. All teeth were subjected to occlusal loading (1,200,000 cycles, 49 N/1.7 Hz) and simultaneous thermocycling (3000 cycles at 5 degrees C/55 degrees C). The percentage of continuous margin of the cervical dentin and enamel was evaluated on replicas using SEM. The teeth were subjected to tracer penetration with either 0.5% basic fuchsin (24 h, 37 degrees C), 2% methylene blue (24 h, 37 degrees C) or 50% silver nitrate solution (4 h, 37 degrees C, followed by 8-h exposure to a photodeveloping solution and overnight fluorescent light). The teeth were mesiodistally sectioned twice. The depth of tracer penetration was measured with a stereomicroscope and averaged for each site. Due to data inhomogeneity and abnormal distribution, both SEM and DP data were transformed. Sample size calculations were performed based on standard deviation and statistical error estimates.

RESULTS

For the dentin margin, there was an acceptable correlation between SEM data and both fuchsin penetration (Pearson: -0.74, p < 0.01) and silver nitrate penetration (Pearson: -0.79, p < 0.01), but not between methylene blue and SEM data. For enamel margins, no significant correlation between SEM and DP data was found for the three tracers. There was statistically no significant difference in tracer penetration between the three tracers (Kruskal Wallis, p > 0.05). For all three tracers, statistically significantly higher penetration occurred at the dentin than at the enamel margin (Wilcoxon, p < 0.05). A sample size of 12 makes it possible to discriminate between materials only when they differ in tracer penetration in the range of 1 mm for enamel and 2 mm for dentinal margins.

CONCLUSION

Tracer penetration with fuchsin or silver nitrate showed a moderate correlation with SEM quantitative marginal analysis data at dentinal margins, but not at enamel margins.

[Microleakage detection in endodontics--a methodological review]

Recently the quality of the root canal filling can only be assessed on the basis of radiological evaluation. The Toronto study proved that the most common cause of the long-term failure of the root canal fillings is the incomplete obturation of the entire root canal system. Present methodological review makes an attempt to summarise the most important microleakage detection methods mentioning their shortcomings too. These methods are very different in their point of views, that is why their results are hardly comparable. There is a need to standardize the microleakage detection methods in order to evaluate more correctly the phenomenon existing between the root canal wall and the root canal filling materials.

Effect of cavosurface margin configuration of Class V cavity preparations on microleakage of composite resin restorations

AIM

The aim of this study was to compare the marginal leakage of hybrid and microfilled composite resin in Class V restorations with and without an enamel bevel.

METHODS AND MATERIALS

Fifty-six cavities were prepared on the buccal and lingual surfaces of 28 extracted human molars using a round bur with the dimensions of 3 x 2 x 1.5 mm. The specimens were divided into two groups of 28 based on the cavosurface margin configuration (beveled and non- beveled). Each group was then divided into two subgroups (n=14) based on the type of composite resin (microfilled and hybrid) used for restoration. After completing restorative procedure, specimens were thermocycled and immersed in 0.5% basic fuchsine. Samples were embedded in polyester and then sectioned both mesiodistally and buccolingually. Dye penetration was observed with a stereomicroscope at 25 x magnification. Statistical nonparametric analysis Kruskal-Wallis and Mann-Whitney tests were performed to compare the data (a=0.05).

RESULTS

There was no statistically significant difference between the two types of composites and two types of enamel margins with respect to microleakage (P>%5). The degree of microleakage at the gingival margin located in dentin of each group was more than that of the enamel margin (P<%5).

CONCLUSION

An enamel bevel in a Class V cavity preparation had no effect on the reduction of marginal leakage using either hybrid or microfilled composite resin.

Microbial Leakage of Gutta-percha and Resilon™ Root Canal Filling Material: A Comparative Study Using a new Homogeneous Assay for Sequence Detection

The sealing ability of gutta-percha/sealer root canal filling was compared to a new thermoplastic synthetic polymer-based obturation material (Resilon TM), using a microleakage model and a new sequence detection assay One Cut Event AmplificatioN (OCEANTM). Eighty-eight extracted human teeth, shaped with K-Files and the ProTaper Technique, were randomly assigned to four groups (n = 22) and obturated in the apical 5 mm. Group R were obturated with the Resilon/Epiphany technique; group GP were obturated with gutta-percha and Zinc oxide eugenoe sealer; group RCH and GPCH received calcium hydroxide intracanal medication before being obturated. Sterilized specimens were inoculated with Enterococcus faecalis and incubated in sterile medium for 47 days. DNA extracted from the specimens was amplified by PCR and then identified by the OCEAN technique. Samples obturated with Resilon root canal filling material showed a greater number of microleakage events than the other groups (p = 0.036). Calcium hydroxide medication did not have a relevant impact on the quality of the apical seal (p = 0.044).

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.

Evaluation of the Quality of the Apical Seal in Resilon/Epiphany and Gutta-Percha/AH Plus–filled Root Canals by Using a Fluid Filtration Approach

This in vitro fluid filtration study compared the apical leakage of root canals that were obturated with Resilon/Epiphany (Resilon Research LLC, Madison, CT) or gutta-percha/AH Plus (GP/AH; DENTSPLY Tulsa, Tulsa, OK) sealer using warm vertical condensation. Fluid flow rate through the filled roots was measured 7 days after the obturations by using a fluid filtration device. Measurements were made before root resection and after 3 to 11 mm of resections. Before any removal of root length, there were no significant differences between the roots filled with Resilon/Epiphany or GP/AH. Analysis of individual root resection results revealed that differences in the fluid flow rate of the two systems occurred only when 9 or 10 mm of the roots were resected with more than half the root length resected when GP/AH Plus leaked more than Resilon/Epiphany. There were no significant differences in the fluid flow rate up to and including 8 mm of root resection. It is concluded Resilon/Epiphany sealed 17-mm root canals as well as gutta-percha and AH Plus sealer and that it does not create a monoblock root filling that does not leak.

Effect of various surface treatments on the microleakage and ultrastructure of resin-tooth interface

This study evaluated the effect of collagen removal and sodium ascorbate treatment of acid-etched dentin on the microleakage and ultrastructure of resin-tooth interface under moist and dry conditions using an acetone-based 1 bottle adhesive system. Class V cavities were made on the buccal surfaces of 90 premolars scheduled for orthodontic extraction. The cavities were etched with 37% phosphoric acid (DPI tooth conditioning gel/India) for 15 seconds. The teeth were divided into six groups with 15 teeth each. In Group 1, the etched surface was blot dried with a dry cotton pellet, leaving it visibly moist, and Prime & Bond NT (Dentsply Detrey/ Germany) was applied. In Group 2, after acid conditioning, the cavity surface was air dried for five seconds, followed by application of Prime & Bond NT. In Group 3, 3% NaOCl (Hyposol, Prevest Denpro Ltd/India) was applied to the acid-conditioned cavity surface for two minutes. The surface was blot dried before bonding. In Group 4, after NaOCl treatment, the surface was air dried for five seconds, followed by application of the bonding agent. In Group 5, 10% sodium ascorbate (chemically pure) was applied to the NaOCl-treated acid conditioned tooth surface for one minute. The surface was blot dried before bonding. In Group 6, after sodium ascorbate treatment as in Group 5, the cavity surface was air dried for five seconds before bonding. The cavities were restored with the hybrid composite Spectrum TPH (Dentsply Detrey, Konstanz, Germany). The teeth were extracted immediately after restoration, and the specimens were prepared for microleakage testing using 2% methylene blue dye and for scanning electron microscopic evaluation. The results of the dye penetration were analyzed with Kruskal-Wallis non-parametric analysis followed by the Mann-Whitney U test at a significance level of p = 0.05. After acid etching, the conventional acid etched groups and groups with NaOCl treatment demonstrated extensive leakage. Sodium ascorbate treatment of the NaOCl-treated dentin significantly reduced microleakage. No statistically significant difference between moist and dry bonding was observed in all groups. Although resin tag penetration improved in both the NaOCl-treated and NaOCl/ascorbate-treated groups, an absence of gap at the resin dentin interface was observed only for the NaOCl/ascorbate-treated groups.

Leakage evaluation of three different root canal obturation techniques using electrochemical evaluation and dye penetration evaluation methods

The aim of this study was to compare the apical sealing ability of three different obturation techniques using an electrochemical evaluation and evaluating dye penetration. One hundred and thirty-two maxillary anterior teeth were randomly divided into six groups. There were 20 teeth in each group. The teeth were obturated as follows: Groups 1 and 4 with Thermafil, Groups 2 and 5 with System B, and Groups 3 and 6 with cold lateral condensation (CLC). The apical leakage in these groups was evaluated using an electrochemical method for Groups 1, 2, 3 and a dye penetration method for Groups 4, 5 and 6. In both methods, the lowest mean leakage values were observed for Thermafil and the highest were observed for the CLC groups. The difference between Thermafil and CLC was statistically significant (P < 0.05). In both groups, System B fillings showed moderate leakage and the difference was not significant with Thermafil and CLC groups.

Chlorhexidine's effect on sealing ability of composite restorations following Er:YAG laser cavity preparation

AIM

The aim of this study was to evaluate the influence of chlorhexidine on microleakage of composite restorations in class V cavities prepared with a carbide bur (CB) and a erbium:yttrium-aluminum-garnet (Er:YAG) laser.

METHODS AND MATERIALS

Cavity preparations were created on the buccal surfaces of 48 bovine incisors using different methods then equally dividing them into four groups. Groups I and II were prepared with a #56 CB in a high speed handpiece while Groups III and IV were prepared with a Er:YAG laser at 350m J/4Hz on enamel and at 80.24 J/cm2 on dentin. The cavity preparations were rinsed with 2% chlorhexidine solution before the application of Clearfill SE Bond system and placement of a Z100 composite resin restoration. After 24 hours, the teeth were polished, thermocycled, and sealed with cosmetic varnish. The samples were then immersed in 2% methylene blue for four hours and sectioned in the buccolingual direction to determine the degree of microleakage.

RESULTS

After statistical analysis (Kruskal-Wallis, p<0.05), no significant differences were verified among the tested groups and between the evaluated cervical or incisal margins of the restoration.

CONCLUSION

The use of the chlorhexidine did not interfere with the adhesion process regardless of whether a CB or the Er:YAG laser were used to prepare class V cavities when restored with the tested self-etching adhesive system.

A Study of Microleakage in Class II Composite Restorations Using Four Different Curing Techniques

For bonded direct Class II restorations, the use of transparent matrices or metal matrices combined with light conducting instruments, such as light tips, should be favored because marginal leakage is significantly lower when compared to using metal matrices alone.

Comparative evaluation of the marginal sealing ability of Fuji VII and Concise as pit and fissure sealants

AIM

The anatomical pits and fissures of the teeth have long been recognized as susceptible areas for the initiation of dental caries. The extreme vulnerability to decay of these pits and fissures on the occlusal surfaces has prompted dental scientists to seek methods of caries prevention. Motivated by the role of pit and fissure sealants in caries prevention, the aim of this study was to compare the efficacy of Fuji VII glass ionomer sealant and Concise resin-based sealant.

METHODS AND MATERIALS

An in vitro study was undertaken using forty premolars extracted for orthodontic reasons. The teeth were divided into two groups and sealants were applied. One was an experimental group using Fuji VII as a pit and fissure sealant and the other a control group using Concise. The teeth were kept in gentian violet dye for 24 hours, the sectioned samples were observed for the extent of dye penetration, and scores were based on established scoring criteria.

RESULTS

The comparison of the performance of the two groups showed a statistically significant difference.

CONCLUSION

The Concise resin-based sealant performed better in terms of sealing ability than did the Fuji VII glass ionomer sealant.

The influence of 2 condensation techniques on the marginal seal of packable resin composite restorations

OBJECTIVE

To evaluate the effect of manual condensation versus a combination of manual and mechanical, or automatic, condensation on the gingival marginal seal of packable resin composite restorations.

METHOD AND MATERIALS

Two packable composites, Pyramid Dentin (Bisco Dental) and Filtek P-60 (3M Espe), were tested. The study consisted of 37 extracted caries-free human molars and premolars. In each tooth, 2 standardized Class 2 cavities were prepared and restored using the incremental technique; the mesial restoration was condensed by hand instrument, and the distal by a combination of the manual and mechanical condenser (KaVo). Restored teeth were subjected to automatic thermal stresses and cycling load stresses. Teeth were immersed in 0.5% basic fuchsin at 37 degrees C for 96 hours. Samples were sectioned mesiodistally in 3 sections. Dye penetration at the gingival margin was examined.

RESULTS

Automatic condensation of Filtek P-60 and Pyramid demonstrated better sealing properties, with a median dye penetration of 0 and 1, respectively (on a dye penetration scale of 0 to 3), compared to manual condensation, median of 2 (P = .043) and 3 (P = .079), respectively. Better sealing ability was shown with P-60 than with Pyramid Dentin when manual condensation was used (P = .037). No significant difference was observed between the 2 products when tested with automatic condensation (P = .066).

CONCLUSION

In this in vitro study the combination of manual and automatic condensation resulted in reduced gingival margin microleakage for both packable composites.

Microleakage of Class II posterior composite restorations with gingival margins placed entirely within dentin

PURPOSE

Composite restorations are more frequently being placed with margins apical to the cementoenamel junction. However, margins within dentin are prone to microleakage. The purpose of this in vitro study was to evaluate various restorative procedures in terms of their ability to reduce microleakage in posterior composite restorations with gingival margins within dentin. We also examined the effect of staining time on microleakage.

MATERIALS AND METHODS

Mesio-occlusal and disto-occlusal preparations were made in 50 extracted molars. Teeth were randomly assigned to receive 1 of 5 treatments followed by restoration with Z100 composite resin: acid etch (control); Clearfil SE Bond; Prompt-L-Pop; Vitrebond/Scotchbond Multipurpose Plus (closed-sandwich technique); or Geristore/Tenure (open-sandwich technique). After 48 hours of water storage followed by sectioning buccolingually, 1 restoration from each tooth was randomly assigned to either 2- or 4-hour immersion in 50% by weight silver nitrate solution. Restorations were removed and gingival floors analyzed to determine the percentage of surface area stained in each of 3 0.5-mm wide zones.

RESULTS

Repeated measures ANOVA did not reveal statistically significant differences in staining for 2 and 4 hours. Compared with the control group, Clearfil SE bond produced statistically significant reductions in leakage in all 3 zones. Prompt-L-Pop did not reduce leakage significantly except in zone 3 (closest to the pulp). Vitrebond and Geristore both reduced microleakage in zones 2 and 3, but the reduction was greater with the use of Vitrebond.

CONCLUSION

Both Clearfil SE Bond and Vitrebond in a closed-sandwich technique were effective methods for reducing microleakage within dentin.

Effect of thermal cycling on microleakage of a fissure sealant polymerized with different light sources

The purpose of this study was to examine the effect of thermal cycling on microleakage of a fissure sealant after it was bonded with different bonding agents and polymerized with different light curing units. To this end, two bonding agents (Xeno III, iBond), three light curing units (Astralis 3, Elipar free-light, Elipar free-light 2), and a fissure sealant (Fissurit FX) were used. Microleakage was then evaluated using a dye penetration method after thermal cycling. When the fissure sealant was polymerized with Elipar free-light and Elipar free-light 2, microleakage at 10,000 cycles was significantly increased compared with that at 5,000 cycles. In terms of comparison among the curing units, the best microleakage score was observed with Astralis 3 (p<0.05). In terms of comparison between the two bonding agents, no significant differences in microleakage score were observed (p>0.05). Further, it was concluded that in order to evaluate microleakage scores appropriately, it was necessary for specimens to be subjected to thermocycling of 10,000 times or more.

Apical seal comparison of low-temperature thermoplasticized gutta-percha technique and lateral condensation with two different master cones

AIM

To compare the apical sealing in mesio-buccal canals of extracted molars obturated with low-temperature thermoplasticized gutta-percha or cold lateral condensation techniques using a .06 or a .02 mm/mm tapered gutta-percha master cone. The secondary aim was to evaluate the depth of spreader penetration in root canals using a .06 or a .02 mm/mm tapered gutta-percha master cone.

METHODOLOGY

Forty-four mesio-buccal curved canals (25-40 degree) were instrumented with .06 nickel-titanium rotary instruments and randomly distributed into two control groups (n=4) and three experimental groups (n=12) for obturation by the Ultrafil 3D system or by cold lateral condensation with .06 or .02 tapered master cone. Canal sealer AH-Plus was used. The depth of spreader penetration was recorded in millimetres. Roots were covered with two layers of nail polish, immersed in India ink for 7 days, transversally sectioned and examined with a stereomicroscope. Student s t test was used to determine whether there was a difference in spreader penetration between groups. Kruskal-Wallis test was used to determine whether there was a difference in leakage.

RESULTS

There were no differences among the three groups (p=0.396), which showed a very similar mean microleakage (0.42, 0.75 and 0.42). The difference in spreader penetration between the groups filled by cold lateral condensation was significant (p=0.001)

CONCLUSION

The Ultrafil 3D system and cold lateral condensation techniques with .06 or .02 tapered master cones were equally effective in the apical sealing of curved canals. The spreader penetrated deeper using a .02 mm/mm tapered gutta-percha master cone.

The accuracy of electrical method for microleakage evaluation by a three-dimensional analysis

OBJECTIVES

This in vitro study aimed to investigate the accuracy of an electrical method for the evaluation of microleakage by a three-dimensional analysis of dye penetration.

METHODS

Coronal cavities were prepared on buccal, palatal or lingual surfaces in extracted human molars. The cavities were then filled with resin composites and were subjected to 10,000 load cycles (425g). Before cavity preparation and after load cycling, physiological saline was applied and wiped off, and the change in conductance was measured across the margin of the restoration in each specimen. After dye penetration, the specimens were reduced by 100 microm in a direction parallel to the cavity floor, from the surface of the restoration to the cavity floor. The sequence of reducing the sections by 100 microm and image taking was repeated. Three-dimensional images of dye penetration were made and the proportions of the interface showing penetration were calculated.

RESULTS

Pearson's correlation coefficients between changes in conductance and the surface area of dye penetration, between these and the rate of dye penetration, and between these and the depth of dye penetration were 0.932, 0.920 and 0.732, respectively. The correlations were significant (p<0.05).

CONCLUSIONS

The results of this electrical method for microleakage evaluation showed stronger correlations with the three-dimensional amount of marginal leakage (surface area of dye penetration and rate of dye penetration) than the two-dimensional amount (depth of dye penetration).

In Vitro Leakage Associated with Three Root-filling Techniques in Large and Extremely Large Root Canals

This study assessed the apical leakage of ultrasonically condensed root fillings in extremely large canals, compared to cold lateral condensation and thermoplastic compaction. Ninety single-rooted teeth were used. In 45 teeth canals were enlarged to size 70 (large). The remaining 45 canals were enlarged to size 140 (extremely large). Each set of teeth was subdivided into three root-filling groups (n = 15): (1) cold lateral condensation (LC); (2) thermoplastic compaction (TC); and (3) ultrasonic lateral condensation (UC). Teeth in all six subgroups were subjected to drawing ink penetration, cleared, and evaluated for linear apical dye leakage. Significantly deeper dye penetration (p < 0.04, Wilcoxon rank-sum test) was observed for LC than for UC. TC did not differ significantly from LC and UC. Dye penetration was significantly deeper (p < 0.0001) in canals enlarged to size 140 than to size 70, independent of root-filling method. Apical leakage associated with ultrasonically condensed root fillings was less than that with cold lateral condensation. It was consistently greater in extremely large canals than that in large ones.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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

Effect of smear layer on sealing ability of canal obturation: a systematic review and meta-analysis

The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro. PubMed was searched for articles published between 1975 and 2005, and results were categorized based on the method of leakage test. Among 26 eligible papers with 65 comparisons, 53.8% of the comparisons reported no significant difference, 41.5% reported a difference in favor of removing the smear layer, and 4.7% reported a difference in favor of keeping it; differences were significant (p<0.001). Of the 65 comparisons, 44 used the dye leakage test for evaluation. The combined effect in this group showed smear layer removal decreases dye leakage (z-score=0.37, z=2.31, p=0.021). According to meta-regression, obturation type, test site and duration, sealer and dye, and publication year had no effect on the results. Under the conditions of these in vitro leakage studies, it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer, did not produce significant effects.

Sealing Ability of New Adhesive Root Canal Filling Materials Measured by New Dye Penetration Method

The sealing ability of new adhesive root canal filling materials was evaluated using a new dye penetration method. Twenty-eight single-rooted mandibular premolars were randomly divided into four groups of seven teeth each and filled by lateral condensation using one of these combinations: Resilon point with Epiphany sealer (RE); gutta-percha point with Sealapex sealer (GS); gutta-percha point with dentin activator and Superbond sealer (GDS); or gutta-percha point with Accel primer, dentin activator, and Superbond sealer (GADS). Amount of 0.06% methylene blue dye solution (MB) that leaked from the coronal portion to the apical area was measured with a spectrophotometer at one, four, eight, 15, and 30 days in an accumulative manner. The total amount of leaked MB on day 30 was significantly higher for GDS than the other combinations (p < 0.05).

Apical microleakage of primary teeth root canal filling materials

OBJECTIVE

The objective of this study was to evaluate in vitro apical microleakage of root canal filling materials for primary teeth.

METHODS

Fifty extracted primary anterior teeth were distributed into 6 groups: 4 experimental groups; 1 negative control group; and 1 positive control group. Zinc oxide and eugenol (ZOE), Kri paste, calcium hydroxide (Ca(OH)(2)), and Vitapex were inserted into the canal using a lentulo spiral mounted in a slow-speed handpiece. All teeth were then subjected to a dye leakage test using 2% methylene blue as the tracer.

RESULTS

The highest dye penetration was recorded for teeth filled with ZOE, with mean values of 9.01+/-1.23 mm. Vitapex showed the lowest dye penetration, with mean values of 4.02+/-1.79 mm. Comparison between groups showed significant difference when the Vitapex and Kri paste groups were compared to the ZOE group (P<.0001). Also, a significant difference between the Vitapex and Ca(OH)2 group (P=.014) was detected. The result showed no difference between Vitapex and Kri paste (P=.658) nor between Kri paste and Ca(OH)(2) (P=.185).

CONCLUSIONS

All the resorbable root canal filling materials used in primary teeth showed apical leakage. The highest apical leakage was recorded for ZOE, while Vitapex showed minimum dye leakage.

Microleakage of three conventional glass ionomers using 45Ca and methylene blue

This study sought to compare the sealing ability of two conventional ionomers and a new intermediate/provisional ionomer formulation using sequential applications of two different tracer methodologies. Thirty freshly extracted (< 6 months) human third molars, stored in 0.1% sodium azide solution, were divided randomly into three experimental groups for preparation of simulated Class V caries at the cementoenamel junction of the facial surfaces. Three materials were used to restore the cavity preparations. After restoration, the teeth were thermocycled for 100 cycles (between 4.0 degrees C and 58 degrees C). To evaluate the microleakage of the materials and compare the tracer's ability to measure microleakage, the teeth were subjected to 45Ca and methylene blue. Treated teeth were bisected longitudinally through the restoration, then each sectioned tooth half was scored by three independent evaluators using a 0 to 4 scale, depending on the tracer penetration. The results showed that all of the materials investigated performed well and no statistical differences were found among the materials, the tracer used, or the margin evaluated.

The leakage resistance of endodontic fiber obturators

Fiber obturators have been introduced into endodontics but few reports exist regarding their efficacy compared to standard obturation materials. This study evaluated the leakage resistance of fiber obturators compared with other obturation materials. All specimens showed a progressive increase in leakage with time. The data indicate that fiber obturation and a new cone/sealer system provide the best canal obturation as evidenced by the leakage behavior.

Coronal sealing ability of three sectional obturation techniques ? SimpliFill, Thermafil and warm vertical compaction ? compared with cold lateral condensation and post space preparation

The purpose of this study was to evaluate the effect post space preparation has on the coronal seal of root canals obturated with cold lateral condensation of gutta-percha compared with the corsonal sealing ability of three sectional obturation techniques not requiring post space preparation. Sixty-eight human maxillary central incisors were divided equally into four groups: cold lateral condensation (Group I), SimpliFill (Group II), Thermafil (Group III) and warm vertical compaction (Group IV). After coronal flaring, all four groups were cleaned and shaped with Lightspeed rotary instruments to a size 60 master apical rotary. After obturation Peeso Reamers were used to create a post space for Group I, while Groups 2, 3 and 4 incorporated the post space in the obturation (sectional technique) and did not require making a post space after obturation. The teeth were then stored in 100% humidity for 1 week and then kept in rhodamine B fluorescent dye for 3 weeks. The teeth were then split open, and the linear dye penetration from a coronal to apical direction (coronal seal) was evaluated with a fluorescent light microscope. Statistical analysis showed that Group I (cold lateral condensation followed by post space made with Peeso Reamers) leaked significantly more (P < 0.05) than the remaining three sectional obturation groups. It was concluded that stresses generated during post space preparation might be detrimental to the seal obtained by the obturation. Sectional obturations with their superior sealing ability offer a viable alternative.

Evaluation of microleakage of roots filled with different techniques with a computerized fluid filtration technique

The aim of this study was to compare the apical leakage of roots filled with different materials using a computerized fluid filtration technique. There were 36 freshly extracted human maxillary central incisors selected. After preparation and irrigation, 3 experimental groups of 10 roots were constituted. Ten roots were filled with AH Plus and gutta-percha, 10 roots were filled with Sealapex and gutta-percha, and 10 roots were filled with Epiphany sealer and Resilon cone using a single cone technique. Three roots were used as a positive control and three roots were used as a negative control group. Evaluation of the apical leakages was performed with a computerized fluid filtration technique. According to the results, the difference between group 3 and 1 and group 3 and 2 was statistically significant (p<0.05). Although group 2 leaked the most, there was no significant difference between group 1 and 2.

Methodologies for assessment of apical and coronal leakage of endodontic filling materials: a critical review

Apical leakage continues to be a topic of great interest, because in spite of the advances in Endodontics, clinical failures still occur. Most failures are probably attributed to the proliferation of bacteria that remain viable after chemical-mechanical preparation and cause periapical tissue irritation. Coronal leakage has aroused researchers' interest over the last few years, since canals may be re-contaminated after loss of coronal sealing or fracture of the remaining tooth. In this review, the various methodologies used for assessing root canal sealing capacity are critically analyzed, as they are not standardized, which makes it difficult to compare the results obtained when different methodologies are used, even though the same substrate is being assessed.

Lack of correlation between ex vivo apical dye penetration and presence of apical radiolucencies

OBJECTIVE

The aim of this study was to determine if there is a significant correlation between the in vivo presence of periapical radiolucency and ex vivo apical dye penetration on the same human teeth.

STUDY DESIGN

Eighty-four endodontically filled teeth that were scheduled for extraction were classified into 2 groups according to the presence or absence of a periapical radiolucency and further divided into 2 subgroups according to the quality of the root canal filling. After extraction, the apical filling was evaluated by a dye penetration method.

RESULTS

The dye extraction evaluation showed no correlation between apical dye penetration and the presence of a periapical radiolucency (not significant), but a statistically significant correlation with the quality of the root canal filling (P = .03).

CONCLUSION

The results of the dye penetration study were correlated to the quality of the root canal filling but had no predictive value for the development of periapical radiolucency.

Evaluation of wear and subsequent dye penetration of endodontic temporary restorative materials

This study evaluated the wear resistance and sealing property of endodontic temporary restoratives by means of functional stressing using a wear simulator. The pulp chamber of 28 extracted molars was opened and filled with cotton, and then the cavity was filled with a temporary material--Caviton, Temporary Pack, Neodyne-alpha, or TERM. Specimens were subjected to a wear test, and data for wear and dye penetration were analyzed by one-way ANOVA independently (p < 0.05). Wear values of Neodyne-alpha (0.09 +/- 0.05 mm) and TERM (0.24 +/- 0.06 mm) were significantly less than those of Caviton (1.79 +/- 0.15 mm) and Temporary Pack (1.02 +/- 0.40 mm). In terms of dye penetration, Neodyne-a leaked significantly less than the other materials at 0.40 +/- 0.32 mm. On the other hand, there were no significant differences between TERM (1.30 +/- 0.57 mm) and Temporary Pack (2.10 +/- 0.12 mm), and between Caviton (2.60 +/- 0.41 mm) and Temporary Pack.

Influence of the methodology and evaluation criteria on determining microleakage in dentin–restorative interfaces

This in vitro study compared microleakage along the dentin-restorative interface using a spectrophotometer protocol and two conventional single-surface methods (scores and percentages), using an organic dye (0.5% buffered methylene blue) or a tracer (50% silver nitrate). Occluso-proximal preparations with gingival margins in dentin were made in 40 human teeth. The teeth were divided into four groups (n=10) according to the solution dyes and adhesive system used: group 1, single bond/methylene blue; group 2, single bond/silver nitrate; group 3, Clearfil SE Bond/methylene blue; and group 4, Clearfil SE Bond/silver nitrate. The dye penetration measurements were made in all groups, using scores and percentages. Groups 1 and 3 were also assessed by UV spectrophotometer. For percentage measurement, the data were submitted to ANOVA and Tukey's test. For the material factor, there was a statistically significant difference between groups 1 and 3. For the dye factor, there was a statistically significant difference between groups 3 and 4. The score results were submitted to Kruskall-Wallis test and showed differences between groups 1 and 3 and groups 2 and 3. For spectrophotometer measurement, no significant difference was observed between groups 1 and 3. The results of dye penetration suggest that there was a difference between dyes and measurement methods, and this should change the interpretation of microleakage tests.

A comparison of four different microleakage tests for assessment of leakage of root canal fillings

OBJECTIVE

The purpose of this study was to compare four different microleakage tests (dye leakage, electrochemical test, bacterial test and fluid filtration) for evaluation of the coronal seal of teeth obturated using Thermafil or lateral condensation techniques.

STUDY DESIGN

One hundred forty-four extracted single-rooted teeth were selected and prepared. The specimens were divided into 8 experimental groups. In 4 groups the root canals were filled with Thermafil obturators and in the other 4 groups by the lateral condensation technique. Coronal microleakage was assessed after exposing one group of specimens (n = 15 teeth) from each of the obturation techniques to each of the four microleakage tests.

RESULTS

In the fluid filtration test, lateral condensation showed statistically less leakage than the Thermafil technique (P < .05). Electrochemical and dye leakage test results showed no difference between the two obturation techniques (P < .05). However, in the bacterial leakage test, Thermafil showed less leakage than lateral condensation (P < .05).

CONCLUSION

There is poor correlation between various methods to evaluate hydraulic leakage. The clinical significance of leakage tests in vitro is questionable.

Furcation Perforation Repair Comparing Gray and White MTA: A Dye Extraction Study

The purpose of this study was to evaluate the ability of gray and white ProRoot MTA to seal furcation perforations in mandibular molars using a dye extraction leakage model. Sixty-four mandibular molars were randomly divided into four experimental groups. Six teeth with perforations were used as positive controls and six teeth without perforations were used as negative controls. Perforations in groups 1 and 2 were repaired with white MTA. Groups 3 and 4 were repaired with gray MTA. Dye leakage was tested from an orthograde direction (groups 1 and 3) and a retrograde direction (groups 2 and 4). After dye extraction, absorbance was measured on a spectrophotometer at 550 nm. No statistically significant difference in leakage was found between gray and white MTA when used as a furcation perforation repair material. However, there was significantly more leakage when the perforations were challenged from the orthograde than the retrograde direction (p < 0.001).

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.

Capillary Flow Porometry to Assess the Seal Provided by Root-End Filling Materials in a Standardized and Reproducible Way

This in vitro study evaluated the root-end sealing ability of gutta-percha + AH26 (GP), Ketac-Fil, Fuji IX (FIX), tooth-colored MTA (MTA), IRM, Ketac-Fil + conditioner (Ketac-FilC), and Fuji IX + conditioner (FIXC). A total of 140 standardized bovine root sections were divided into seven groups, filled with the mentioned root-end filling materials, and, at 48 h, submitted to capillary flow porometry to assess minimum, mean flow and maximum pore diameters. Results were statistically analyzed using nonparametric Kruskal-Wallis and Dunn tests. Level of significance was set at 0.05. Using the Kruskal-Wallis tests we found that there was no significant difference between the minimum pore diameters of the different materials, but significant differences between the mean flow (p < 0.001) and maximum (p < 0.001) pore diameters could be demonstrated. For the mean flow pore diameters, there was a significant difference between FIX and all other materials, between Ketac-Fil and IRM and between Ketac-FilC and IRM. Concerning maximum pore diameters, there was a significant difference between FIX and all other materials, between Ketac-Fil and MTA, GP and IRM, FIXC and IRM, and Ketac-FilC and IRM. The data showed that each sample had leaked. Glass ionomer cements leaked more than other materials, although dentin conditioning diminished the maximum through pore diameters. This maximum pore diameter, which corresponds to the largest leak in the sample, together with the size of bacteria and their metabolites, will be indicative of the eventual leakage along the root-end filling materials.

Analysis of the sealing ability of different obturation techniques in oval-shaped canals: a study using a bacterial leakage model

The aim of this study was to evaluate the sealing ability of 3 obturation techniques in oval canals using a bacterial leakage model. Seventy mandibular incisors with oval canals were selected after buccolingual and mesiodistal radiographs, and divided into three groups. After instrumentation, the canals were obturated respectively by lateral condensation (G1), warm vertical condensation (G2) and Thermafil (G3). Five root canals were not obturated and served as positive controls; five teeth with intact crowns served as negative controls. All teeth were mounted on a 2 chamber apparatus and then exposed to human saliva. The number of days required for the entire contamination of the root canals was recorded, observing the turbidity of the BHI broth, for a period of 100 days. 84.21% of the samples from the lateral condensation group (G1); 84.21% of the samples from the warm vertical condensation group (G2); and 89.47% of the samples from the Thermafil System group (G3) showed no contamination at the end of the study. No statistical significant difference was found among the three techniques. The quality of the apical seal in the three techniques tested was similar.

Marginal integrity and microleakage of direct and indirect composite inlays: SEM and stereomicroscopic evaluation

The aim of this study was to evaluate the microleakage of direct and indirect composite inlays by stereomicroscopy and scanning electron microscopy (SEM). Thirty bovine incisors were ground to obtain an incisal platform, simulating the occlusal surface of a human molar. Each tooth received two 8 degrees proximal cavities with cervical finishing line prepared in dentine or enamel. One of the cavities was filled with Filtek Z250/Single Bond, using the direct technique, and the other was filled with with Solidex/Rely X ARC/Single Bond, using the indirect technique. The samples were stored in water at 37 degrees C for 24 hours and placed in a 50% silver nitrate solution for 6 hours in a dark container. Next, the samples were washed under running water, immersed in a developing solution and exposed to fluorescent light for 12 hours. The teeth were then severed and evaluated for dye penetration by stereomicroscopy and SEM. There were no significant differences between the direct and indirect techniques for the cervical finishing line in enamel, but for the finishing line in dentin, the indirect technique allowed less microleakage than the direct technique. SEM analysis showed leakage similar to that observed by stereomicroscopic analysis. The use of stereomicroscopic and SEM evaluations improves microleakage analysis.