Measurement Of Dye Penetration Research Articles

A Comparative Evaluation of the Bonding Strength, Marginal Adaptation, and Microleakage of Dental Cements in Prosthodontics: An In Vitro Comparative Study.

The primary function of dental cement is to seal and support prosthodontic restorative materials. Proper selection of the dental cement contributes to the clinical success of the restoration. A total of 166 molar tooth samples were prepared to simulate the type of toothcommonly found in prosthodontic practice. Each sample was restored using one of the tested dental cement materials employing a prestabilized methodology. The performance of resin-modified glass ionomer cement (RMGIC) (GC Fuji PLUS Capsule, GC America, Alsip, IL), zinc phosphate cement (ZPC) (Dentsply Sirona, Charlotte, NC), and resin cement (RC) (RelyX ARC, 3M ESPE, Saint Paul, MN) in bonding strength, marginal adaptation, and microleakage was evaluated and compared. The bonding strength, marginal adaptation, and microgroove were tested using specific established methodologies. The outcomes were then analyzed using statistical analyses for means and standard deviations to compare different types of dental cement. The total outcome shows that the highest bonding strength with the highest mean was the resin cement, rating 24.8 MPa, followed by RMGIC and ZPC at 20.5and 18.9 MPa, respectively. The marginal adaptation scores indicate that RC had the highest score at a mean of 4, followed by ZPC at 3.2 and RMGIC at 2.5. The dye penetration measurements in millimeters revealed that ZPC had a penetration of 0.31 mm, RMGIC had a penetration of 0.25 mm, and RC had the least penetration at 0.20 mm. The results of the statistical data analysis show significant differences between the dental cements in bonding strength and marginal adaptation. In conclusion, resin cement demonstrated superior performance in bonding strength, marginal adaptation, and resistance to microleakage compared to RMGIC and zinc phosphate cement. These findings highlight the importance of selecting resin cement for achieving optimal clinical outcomes in prosthodontic restorations.

Microleakage comparison in temporary restorative materials in complex endodontic cavity

To compare the mean microleakage (in millimeters) around two temporary restorative materials (zinc-oxide based versus light-cure resin based) at tooth-temporary restoration and temporary-permanent restoration interfaces, within the complex endodontic access cavities in the extracted human teeth. Thirty teeth randomly allocated into 2 experimental groups in this in-vitro experimental study. Teeth in each group had conventional class II cavities prepared and restored with the composite filling. After 14 days of aging in saline, complex endodontic access cavities were prepared in these teeth. This was followed by placement of either of the temporary restorative materials to seal the access cavities. After immersion in 1% methylene blue dye, teeth were sectioned and observed under stereomicroscope (magnification X25.6) Measurement was made at two interfaces ‘a’ and ‘b’ (temporary restoration-tooth and temporary restoration-pre-existing restoration), respectively. Depth of dye penetration in millimeters was recorded as the microleakage. Independent sample t-test was applied to compare the mean difference in dye penetration measurements in the two study groups at interfaces ‘a’ and ‘b's. A p-value of < 0.05 was taken as statistically significant. Light-cure resin-based material showed microleakage of 0.14 ±0.26 mm at interface ‘a’ and 0.07 ±0.17 mm at ‘b’, respectively. Whereas zinc-oxide based temporary restorative material showed microleakage of 0.54 ±0.42 mm at ‘a’ and 0.88 ±0.51 mm at ‘b’ interface. In complex endodontic access cavity, compared to zinc-oxide based material, light-cure resin-based material showed significantly less microleakage at the tooth-temporary restoration and pre-existing permanent filling-temporary restoration interfaces.

Marginal quality of a full-body bulk-fill composite placed with an universal adhesive system in etch-and-rinse and self-etch mode: An in vitrostudy.

BackgroundMarginal seal of a nanohybrid bulk-fill composite compared to a nanohybrid conventional composite, using a universal adhesive (UA) applied in etch-and-rinse (ER) and self-etch (SE) mode was investigated. Material and MethodsThirty-six intact molars were selected and two standardized cavities in each tooth were prepared and allocated into four groups according to restorative material and etching strategy. All samples were placed in a 1% methylene blue solution for 24 h, then cut in the middle of the restorations obtaining two parts (n=144) and used for microscopic evaluation (50x) for dye penetration measurements. ResultsThe data were analysed by ANOVA and Tukey post-hoc test (p<0.05). Marginal seal was influenced by adhesive strategy (p<0.05) but not from the composite used (p>0.05). ConclusionsSimplified restorations with nanohybrid bulk-fill composite showed comparable marginal leakage to incrementally placed nanohybrid composite. The UA used with a ER technique resulted in better marginal seal irrespective of the restorative material used. Key words:Bulk-fill composite, universal adhesive, self-etching, etch-and-rinse, marginal seal.

Evaluation of Microleakage in Single-Rooted Teeth Obturated with Thermoplasticized Gutta-Percha Using Various Endodontic Sealers: An In-Vitro Study.

To compare apical microleakage of extracted, single-rooted teeth obturated with thermoplasticized injectable gutta-percha using two different endodontic sealers (calcium-hydroxide and resin based). An experimental study. The Aga Khan University Hospital (AKUH), Dental Clinics and Laboratory from June to September 2015. The study was conducted using extracted teeth. After access cavities were made, cleaning and shaping of root canals was done in 70 teeth. Teeth were randomly allocated into two groups and obturated with thermoplasticized injectable gutta-percha (Obtura II) using two sealers (Sealapex vs. AH plus). After immersing the teeth in 2.0% methylene blue, they were split longitudinally, viewed under light microscope (magnification X4) and images were taken by a camera connected to microscope. The extent of dye penetration was assessed from apex to its coronal part and recorded in millimeters. Independent sample t-test was used to compare microleakage in the two groups. Pearson correlation coefficient was used for inter-examiner reliability of dye penetration measurements. A p-value of <0.05 was taken as statistically significant. Teeth obturated with Obtura II gutta-percha with AH plus sealer had a mean dye penetration of 1.20 ±0.79 mm. This was significantly better than Obtura II with Sealapex sealer (p=0.003). Obtura II-AH plus sealer was a better combination for obturation as it showed a lesser degree of microleakage. Obtura II with Sealapex group showed higher microleakage, so this combination should be avoided in single-rooted teeth.

The effect of immediate versus delayed dowel space preparation on the apical seal of Resilon/Epiphany obturation system

Aim: The aim of this in vitro study was to compare the effect of immediate versus delayed dowel space preparation using two techniques (peeso reamers and hot pluggers) on the apical seal of Resilon/ Epiphany obturation system.Methodology: Fifty freshly extracted human teeth with single and straight canals were used in this study. The roots were instrumented using the step-back technique, K-files with circumferential filing action and copious irrigation of 2.5% sodium hypochlorite and 17% solution of aqueous EDTA to remove smear layer. The canal obturation of all roots was performed with lateral condensation technique using Resilon/Epiphany Obturation system. Then the obturated roots were randomly distributed into 5 experimental groups (10 teeth for each group); one control group, and 4 experimental groups according to the technique of dowel space preparation (peeso reamers and hot pluggers) either immediately after obturation or after one week later. After this period, the external surfaces of all roots were coated by two layers of sticky wax except for the apical 2 mm and were submerged in 2% methylene blue dye for 3 days at 37ºC. Then all roots were longitudinally sectioned for linear measurement of dye penetration through the apical foramen using a stereomicroscope. The data obtained were analyzed statistically using ANOVA and Student t-tests.Results: Significantly more apical leakage (P&lt;0.05) in groups that received delayed dowel space preparation using either peeso reamers or hot pluggers compared with control group and no significant differences (P&gt;0.05) between immediate and delayed dowel space preparation using either technique.Conclusion: Resilon/ Epiphany obturation system can received immediate and delayed preparation using conventional methods of dowel space preparation, however immediate preparation was preferred according to the results of this experiment.

The effect of dowel space preparation on the apical seal of Resilon &amp; Gutta-percha obturation materials. (An in vitro comparative study

Aim: The aim of this in vitro study was to compare the effect of immediate versus delayed dowel space preparation using peeso reamers on the apical seal of roots filled by Gutta-percha with two types of resin based-sealers (AH26 and AH Plus) and by Epiphany obturation system.Methodology: Sixty freshly extracted human teeth with single and straight canals were used in this study. The roots were instrumented using the step-back technique, instrumentation was accomplished by using the Gates-Glidden drills with copious irrigation of 2.5% sodium hypochlorite and 17% solution of aqueous EDTA to remove smear layer. The roots were randomly divided into 3 main groups according to the type of obturation materials using lateral condensation technique (20 teeth for each group):Group A: Gutta-percha + AH26 root canal sealer.Group B: Gutta-percha + AH Plus sealer.Group C: Resilon+ Epiphany sealer+ prime. (Epiphany obturation system)Then each group divided into two subgroups according to the time of dowel space preparation either immediately after obturation or after one week. The external surfaces of all roots were coated by two layers of sticky wax except for the apical 2 mm and were then submerged in 2% methylene blue dye for 3 days at 37ºC. After that, all roots were longitudinally sectioned for linear measurement of dye penetration through the apical foramen using a stereomicroscope. The data obtained were analyzed statistically using ANOVA and Student t-tests.Results: Significantly less apical leakage in roots filled by gutta-percha with AH Plus than those filled by gutta-percha with AH26 and those filled by Epiphany obturation system for delayed dowel space preparation (P&lt; 0.05) and there was a significantly less apical leakage in roots filled by Epiphany obturation system that prepared immediately after obturation than those received delayed preparation (P&lt; 0.05).Conclusion: All the groups had apical leakage what ever the type of obturation material or time of dowel space preparation.

Repair of root canal perforation by different materials

Background: The aim of this in vitro study was to compare sealing ability of Mineral Trioxide Aggregate (MTA), Glass ionomer cement (GIC) and Epiphany obturation system in repairing the iatrogenic lateral root canal perforation. Materials and Methods: Thirty freshly extracted human teeth with single and straight canals were used in this study. These teeth were cleaned and their crowns were removed at the cemento-enamel junction. The roots were instrumented using the step-back technique. A perforation was created on the mesial root surface at about 45- degree angle to the long axis of each root apico-coronally at the middle third by small round bur #1/2 with copious irrigation of 2.5% NaOCL and 17% buffered solution of EDTA was used as the final rinse to remove the smear layer and to prevent the blockage of perforation. The 30 roots were divided randomly in to three groups (10 roots for each group):- Group A: The root canal perforation was repaired by MTA then obturated by lateral condensation technique with gutta-percha and zinc oxide eugenol sealer. Group B: The root canal perforation was repaired by GIC then obturated by lateral condensation technique with gutta-percha and zinc oxide eugenol sealer. Group C: the roots were obturated with Epiphany obturation system by lateral condensation technique. The external surfaces of all roots were coated by two layers of sticky wax except the perforation site then immersed in 2% methylene blue dye for 48 hrs in incubator at 37C°. After that all roots were longitudinally sectioned for linear measurement of dye penetration through the perforation using a stereomicroscope at X40 magnification with calibrated scale ocular grid. Results: The result showed that group A showed the lowest mean of dye leakage (0.77mm) while group C showed the highest mean of dye leakage (4.45mm). Conclusion: Significantly less dye leakage in roots which perforations repaired by MTA than those repaired by GIC and highly significant less dye leakage than those repaired by Epiphany obturation system.

The Effects of Surface Pretreatment on the Microleakage of Resin-Modified Glass-Ionomer Cement Restorations

To evaluate the effect of different surface pretreatments on the marginal microleakage of Vitremer restorations. Class V cavities were prepared on the labial and lingual surfaces of extracted human third molar teeth. Cavities were randomly distributed into six groups according to surface treatment, as follows: Group NC (negative control): no surface treatment; Group VP (positive control): Vitremer Primer; Group PA: 32% phosphoric acid; Group PAA: 20% polyacrylic acid; Group PLP: self-etch adhesive (Prompt L Pop); Group PB: etch & rinse adhesive (Prime & Bond NT). All cavities were restored with Vitremer. Teeth were thermocycled, stained with 0.5% basic fuchsin dye and sectioned. Microleakage values were quantitatively assessed by linear measurement of dye penetration using image-analyzing software. Differences between occlusal and gingival microleakage values within groups were evaluated using paired t-tests, and differences among groups were analysed using one-way analysis of variance (ANOVA) and Tukey tests. There were statistically significant differences between the occlusal and gingival microleakage values for all groups (p < 0.05). Microleakage differed significantly among surface pretreatment groups (p < 0.001). The negative control and PLP groups showed similar microleakage values, but were significantly higher than other groups for both margins. Although there were no statistically significant differences between positive control and PA, PAA, PB groups, microleakage values of positive control group were smaller than all other experimental groups except for PB group. Vitremer restorations require surface pretreatment to prevent excessive microleakage. Pretreatment with etch & rinse adhesives and Vitremer Primer may reduce microleakage of Vitremer restorations.

Influence of gutta-percha cone disinfection on leakage: comparison of two sealability assessment methodologies

Aim: To clarify the influence of 5.25% sodium hypochlorite disinfection of gutta-percha cones on leakage and to compare the outcomes of two sealability assessment methodologies (fluid filtration and dye penetration methods). Methods: Thirty teeth were prepared and filled using the guttapercha lateral condensation technique. Group I was filled with gutta-percha cones disinfected with sodium hypochlorite 5.25%, while Group II was filled with cones that were not disinfected. Apical leakage was measured using: (a) fluid filtration technique and (b) linear measurement of dye penetration after clearance. Results: The Student’s t-test showed no significant difference between the groups for both techniques (p<0.05). Conclusions: Both methodologies employed, even with the inherent limitations, were capable of identifying sealing failures. The disinfection of gutta-percha cones with 5.25% sodium hypochlorite did not alter apical leakage.

Effect of C-factor and LED Curing Mode on Microleakage of Class V Resin Composite Restorations

To investigate the effects of cavity C-factor and LED curing mode on microleakage of class V resin composite restorations. Eighty extracted human maxillary premolars were divided into four groups. In groups I and II, V-shaped class V cavities (C-factor ≈ 1.5) were prepared while box-shaped class V cavities (high C-factor ≈ 4) were prepared in groups III and IV. All the cavities were prepared on the vestibular surfaces of the teeth. All the cavities were prepared by one operator with specific dimensions. The same adhesive system (Excite) and the same restorative composite (Tetric Ceram) were used in all the groups. The restorations in groups I and III were cured with the fast curing mode of LED curing light, while the restorations in groups II and IV were cured with the soft-start mode of the same curing light. The samples were thermocycled, immersed in a 0.5% basic fuchsin solution for 24 hours, and sectioned. The degree of dye penetration was measured quantitatively and then qualitatively at both enamel and dentin/cementum margins. Quantitatively, there was no statistical difference in the degree of microleakage between the groups at the enamel margin (P>.05). At the dentin/cementum margin, group III showed significantly more dye penetration than the other groups (P<.001). Similarly, qualitative measurements of dye penetration showed that group III had higher microleakage at dentin/cementum margin than the remaining groups (I and III P<.001; II and III P<.01; III and IV P<.01). Paired sample statistics showed that microleakage at the dentin/cementum margin was not statistically different from enamel mi-croleakage (P>.05), except for group III (P<.000). Fast curing mode of LED curing light resulted in more microleakage at the gingival floor of class V cavities with high C-factor. There was no difference in dye penetration between enamel and dentin margins of the cavities except when the fast curing mode was used with high C-factor cavities. Both quantitative and qualitative measurements of microleakage gave the same results at both enamel and dentin margins.

An evaluation of nanocomposites as pit and fissure sealants in child patients

Dental caries affects populations of all ages in all the regions of the world, with the child patient being at the highest risk. Fifty percent of the permanent molars are decayed by the age of 12, due to lack of information about protection and occlusal morphology. Pit and fissure sealing undoubtedly plays a fundamental role in preventing occlusal caries. The most common approach to assess the sealing ability of pit and fissure sealants of tooth/restoration is the measurement of dye penetration along the interface. The present study aims to evaluate the microleakage and penetration depth of three different types of dental materials, namely (A) Conventional pit and fissure sealant, (B) Flowable composite, (C) Flowable nanocomposite. This in-vitro comparative study comprised of extracted human posterior teeth mounted as blocks. In the present study, microleakage and penetration depths of conventional sealants/flowable composite and nanocomposite were measured with the help of a dye under stereomicroscope. A student't' test and Analysis of variance (ANOVA) tests were performed to compare the mean microleakage and penetration depth. Microleakage was found to be highest for the flowable composites, and least for the conventional sealant. The nanocomposite values were intermediate. Penetration depth was highest for nanocomposite and least for flowable composite. According to the results, the nanocomposite was found to be an excellent dental material for penetration in deep pits and fissures, though it exhibits mild microleakage. Hence, it can be recommended for use in pediatric dental patients, as a pit and fissure sealing agent.

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.

Apical Microleakage of Root-End Cavities Prepared by CO 2 Laser

This in vitro study in extracted human teeth was designed to compare the degree of dye penetration of root-end cavities prepared by CO2 laser, ultrasonic retrotip, or rotary instrument. Eighty-two human anterior teeth were prepared and obturated with laterally condensed gutta-percha and sealer. Root-end resection was performed at 90 degrees, 3 mm from apex. Root-end cavities were prepared by CO2 laser beam, ultrasonic retrotips, or bur and were filled with amalgam. The teeth were isolated and immersed in basic fuchsin at 36 degrees C for 48 hours. The roots were split longitudinally and examined by a stereomicroscope. Leakage was quantified by linear measurement of dye penetration with the aid of image-analyzing software. Apical leakage in the CO2 laser group was significantly less than in the ultrasonic retrotip and bur groups. The difference between the ultrasonic and bur groups was insignificant. Based on the results of this in vitro study, application of CO2 laser for root-end cavity preparation appears to decrease the apical leakage.

Effect of bleaching on microleakage of resin composite restorations in non-vital teeth: An in-vitro study

Non vital bleaching has enjoyed wide success in the treatment of discolored papules teeth. It has been that residual hydrogen peroxide in the bleaching agent affects the resin tooth interface. This study was undertaken to evaluate the effect of different application times of bleaching agent on the tooth resin interphase. 40 human freshly extracted maxillary incisors were taken and root canal treatment was completed. The teeth were divided in 4 groups, with 1st group teeth no bleaching, 2nd group teeth bleached for 2 days, 3rd group teeth bleached for 4 days and the last group teeth were bleached for 7 days. Access cavities were restored with composite resin. Silver nitrate dye was used for dye penetration test. The longitudinal sections were evaluated under stereomicroscope for the measurement of dye penetration. It was concluded that the bleaching agent definitely affects the seal at the tooth resin interphase and microleakage increase with increased bleaching time.

Comparison of canal shaping methods with GT™ rotary file and condensation methods

The purpose of this study was to compare the shaping time of two shaping methods and the leakage of three different obturation techniques. Ninty three canaled human molar teeth were used, which were randomly divided into two groups of forty teeth each and ten control teeth. After working length determination, the one group was prepared crown-down technique using rotary root canal instruments of GT rotary files .12/20, .10/20, .08/20 and .06/20 taper(Maillefer Instrument SA. Switzerland). The other group was instrumented with Gates Glidden burs(#1, #2, and #3) to coronal preparation and GT rotary files .08/20 and .06/30 taper to apical preparation. Shaping time was measured. After root canals were instrumented, they were divided to three subgroups and obturated as follows : Subgroup 1, obturated with single cone method Subgroup 2, obturated with lateral condensation : Subgroup 3, obturated with continuous wave technique. Three subgroups were obturated using non-standardized gutta-percha cone(Diadent, Korea, .06 or .08 taper) and AH-26(Dentsply DeTrey, Germany) as a root canal cement. Ten unobturated teeth served as positive and negative controls. After immersion in 2% methylene blue solution for 1 month, the teeth were washed during 24h. The teeth were demineralized in 10% nitric acid and dehydrated by immersion in 80, 90 and 100% ethyl alcohol. The teeth were finally cleared and stored in 100% methylsalicylate, and apical dye penetration was evaluated under stereomicroscope(Leica M420, LC, U.S.A)at 8.75 magnification. Liner measurement of dye penetration was assessed with the use of digitalized image analysing system (analySIS, GmbH, Germany) The data were analysed statistically using independent T-test and Two-way ANOVA and Tukey test. The result were as follows 1. In canal prepared with GT rotary file, shaphing time taked more than the group of using Gates Glidden drill to coronal preparation without statistical significance (p>0.05) 2. The group of single cone obturation using canal preparation of GT rotary files showed significantly more apical leakage than those of lateral condensation and continuous wave technique regardless of shaping method (p rotary files and Gates Glidden drill showed significantly more apical leakage than those of continuous wave technique regardless of shaping method (p0.05). 5. The group of single cone obturation using canal preparation of GT rotary files and Gates Glidden drill showed more apical leakage than the group of lateral condensation using same shaping method with-out statistical significance (p＞0.05).

Dye penetration in dry and water‐filled gaps along root fillings

The aim of this study was to investigate the influence of hydration in voids along root fillings on methylene blue penetration. A total of 80 human root canals were prepared using a step-back technique and filled with a zinc oxide based sealer and gutta-percha. Leakage along the fillings was measured by a transport fluid model and classified into three categories: gross leakage (GL), slight leakage (SL) and no leakage (NL). Specimens with NL and SL were immersed into methylene blue (MB) 2% for 24 h (group I). Specimens with GL which had wide gaps filled with water were randomly divided into two groups (II, III). Transport air was applied to remove water from gaps only in specimens of group III. All tested specimens from groups II and III were also immersed into MB 2% for 24 h. Each specimen was then split longitudinally and linear measurements of dye penetration were recorded. Group III (with dry gaps) showed significantly more dye penetration than group II. No significant difference was found between group I and group II. Methylene blue penetrates along root fillings more easily in dry gaps than in water-filled gaps.

Adaptation and sealability of two contemporary obturation techniques in the absence of the dentinal smear layer

The aim of this study was to evaluate the adaptation and short- and long-term sealability of two different thermoplastic techniques--a core carrier technique, Thermafil; and a warm vertical continuous wave of compaction technique, System B. Fifty-one mesial roots of mandibular molars with separate canals, patent canal orifices and curvature greater than 15 degrees were cleaned and shaped with Orifice Shapers and ProFile.04/.06 taper Ni-Ti rotary files using 5.25% NaOCl and 17% REDTA to a size 30.04 taper Profile at the apex to create a continuous tapered preparation. Canals were randomly obturated with Sealapex root canal sealer and either alpha-phase gutta-percha on a plastic Thermafil carrier, or nonstandardized beta-phase gutta-percha using the System B heat source. Proximal radiographs of roots were evaluated by three examiners based on established criteria for overall material adaptation, apical adaptation and filling material extrusion. Teeth were randomly separated into three groups of 17 each and placed in black India ink for 10 days, 24 h, or after 67 days storage in Hank's Balanced Salt Solution. All roots were demineralized and rendered transparent. Three examiners evaluated the apical leakage by the linear measurement of dye penetration under the stereo-microscope. The movement of filling material into canal irregularities was also evaluated. Both obturation techniques were not significantly different in the overall canal obturation and in the apical third adaptation (P > 0.05). Significantly more filling material extrusion beyond the apex was noted with the Thermafil technique (P < 0.001). No significant difference was found amongst the 67-day, 10-day and 24 h System B groups (P > 0.05). The 67-day Thermafil group showed significantly more leakage than the 10-day and 24 h Thermafil groups. There was a significant difference in the degree of leakage between the 67-day Thermafil group and the 67-day System B group (P < 0.05), but not between the 10-day and 24 h groups (P > 0.05). Both obturation techniques produced substantial filling material movement into canal irregularities. It was concluded that Thermafil demonstrated more filling material extrusion beyond the apex and significantly more long-term apical leakage.

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

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

Effect of smear layer on coronal microleakage

The purpose of this study was to examine the effect of smear layer on coronal microleakage. Fifty-two single-rooted extracted human teeth with a straight root canal were chemomechanically prepared and equally divided into experimental groups A and B. The teeth in group B were treated with ethylenediamine tetraacetic acid and sodium hypochlorite to remove the smear layer. All teeth in the experimental groups were next obturated with gutta-percha and sealer. Finally they were tested for dye leakage with methylene blue. Linear and volumetric measurement of dye penetration was used to assess leakage. The results of this study suggest that the removal of smear layer significantly improves the tightness of the sealing in the coronal area.

Influence of criteria on the results of in vitro evaluation of microleakage

Objectives. The aim of this study was to compare and explain the statistical methods employed to evaluate the in vitro sealing efficiency of adhesive restorative systems. Methods. Two hundred and sixty sound freshly extracted human premolars were randomly divided into 13 groups. Standardized cavities were prepared, and the teeth were restored with 13 restorative systems. The teeth were thermocycled, immersed in dye, embedded in resin and sectioned. Five evaluation criteria were recorded: mean, median and mode of the data measured on each tooth, maximum dye penetration measurements on each tooth, and percentage of teeth in each group without any dye penetration. For each parameter, one-way ANOVAs and Duncan a posteriori tests were used to compare the 13 systems. Results. The number of non-statistically different subgroups, pointed out by Duncan tests, was greater when the selected criterion was the maximum dye penetration (6 subgroups) or the percentage of teeth without any penetration (5 subgroups) than when the criterion was the median (3 subgroups), the mode or the mean (4 subgroups). The positioning of the 13 adhesive restorative systems established from the five criteria was different. Equivalent adhesion strategies revealing different experimental results indicate that other factors contribute to the final effectiveness of a particular system: clinical approach with respect to the formation of an elastic bonding layer, and shrinkage, physical and rheological properties of resin composite. Significance: The results of these in vitro studies of dye penetration must be considered as comparisons and not as absolute conclusions. The maximum dye penetration measured on each tooth, which complies with the aim of the in vitro evaluation of sealing efficiency defined by Pashley (1990) and allows powerful statistical analysis of results, seems to be the best evaluation criterion.