The effect of thermocycling in microleakage analysis.

The purpose of this study was to evaluate the effect of thermocycling on dye penetration during in vitro microleakage analysis of composites. Fifty non-carious human molars, stored in 75% ethanol, were divided into five groups (N = 10). Each tooth was prepared for a MOD slot preparation using a high speed handpiece and water, one proximal cervical margin in cementum, the other in enamel. The enamel margins were etched, rinsed, dried, and the composite inserted and cured in multiple increments. Group A was not thermocycled (TC) and was immersed in 0.5% basic fuchsin dye for 24 h at 37 degrees +/- 1 degrees C. Group A' was not TC and was immersed in 0.5% basic fuchsin dye for 4 h at 37 degrees +/- 1 degree C. Group B was TC in a water bath and immersed in dye as with Group A, Group B' was TC and immersed in dye as in Group A'. Group C was TC, as in Group B, but in a basic fuchsin dye bath. Thermocycling consisted of 250 cycles, 15 s dwell time each in 5 degrees C and 50 degrees C bath. The teeth were mounted in acrylic, and multiple cross-sections of all surfaces were prepared. Dye penetration was read on a scale of 0 (no leakage) to 4 (leakage to the pulpal floor) and means calculated for each surface and tooth. There was no significant increase of microleakage in restorations when thermocycling was used to simulate temperature extremes, either in dye or water baths, as opposed to restorations which were not thermocycled.     

Studies on the marginal leakage around various restorative materials. Part 1: Testing method and condition (author's transl)]

Standardized cavities prepared in bovine teeth were restored with 4 types of filling materials, lathe-cut amalgam, spherical amalgam, silicate cement and composite resin. Restored teeth were immersed in 4 degrees C and 60 degrees C dye solution alternately by automatic device which makes it possible to change the immersion interval and number optionally. By means of measuring the depth of dye penetration, the marginal leakage induced during the thermal change was evaluated and the effects of the immersion interval and number were investigated. Results are as follows. 1) It is possible to obtain the marginal leakage quantitatively by means of measuring the depth of dye penetration. 2) The marginal leakage around various restorations are significantly influenced by the immersion interval and number. 3) The depth of dye penetration varies with types of filling materials. 4) The optimum immersion interval and number are 2 minutes and 60-120 times to evaluate the marginal leakage around various restorative materials.     

Coronal microleakage of three temporary restorative materials: an in vitro study

The sealing properties of three temporary restorative materials, Cavit, IRM, and a polycarboxylate-based cement, Ultratemp Firm, were investigated in vitro. Standardized access cavities were prepared in 45, intact, extracted, human molars. The teeth were randomly assigned to three groups and the access openings filled with one of three temporary filling materials. In five teeth (negative control), no restorative material was placed but the preparations were coated entirely with sticky wax. The five teeth of the positive control group had no restorative material and no sticky wax applied. After thermocycling for 500 cycles (5-55 degrees C), the experimental teeth were dipped in molten sticky wax to the CEJ. The coronal enamel was subsequently coated with two layers of nail varnish, leaving an area of 1 mm around the filling material uncovered. The samples were then immersed in 2% methylene blue dye solution for leakage assessment. The teeth were sectioned and the greatest depth of dye penetration was recorded. Positive control sections exhibited complete dye penetration, whereas negative controls had none. There was no statistically significant difference in marginal leakage between Cavit, IRM, and Ultratemp Firm (p > 0.05). All materials leaked at the interface material-dentin, whereas some IRM specimens absorbed the dye into the bulk of the material.     

Apical leakage in root canal fillings performed with two types of cement following application of Nd: YAG laser or EDTA solution in the root canal walls

Marginal apical leakage was evaluated in root canal filling performed with two sorts of cements after applying Nd:YAG laser or an EDTA solution in the root canal walls. Sixty-two human lower premolars had their canals instrumented through mechanical technique. Afterwards the external root surfaces were impermeabilized, except for the foramen. The roots were then divided into 4 groups of 15, according to the type of treatment performed on the root canal walls and the type of cement utilized in the filling. Group I - application of Nd:YAG laser and filling with AH Plus cement; Group II - application of Nd:YAG laser and filling with Endofill cement; Group III - application of EDTA for 5 minutes and filling with AH Plus cement; Group IV - application of EDTA for 5 minutes and filling with Endofill cement. Two teeth served as negative and positive controls. Afterwards, the roots were immersed in a 2%-methylene blue dye, for 48 hours. Wearing of the roots took place following the removal of impermeabilization for the reading of leakage magnitude, by means of a light microscope through planimetry technique The results indicated AH Plus cement as the one to allow the least apical leakage, as well as Nd:YAG laser application, when utilized in the treatment of root canal walls, prior to filling.     

Sealing capacity in vitro of thermoplasticized gutta-percha with a solid core endodontic filling technique

Abstract— This study assessed the sealing capacity of two endodontic gutta-percha filling techniques. Thirty-four single-rooted fully developed teeth were endodontically accessed, instrumented and randomly divided into two experimental groups ( n =12) and two control groups ( n =5). In Group A, root canals were obturated using a solid core thermoplastic technique (Densfil), in Group B and Group C (negative control) canals were obturated with laterally condensed gutta-percha, and in Group D (positive control) canals were left un-obturated. AH-26 was used as the sealer. Two days later, the teeth were conventionally prepared for testing apical and coronal leakage, immersed in india ink for 5 days and subsequently cleared. The linear coronal and apical extent of dye penetration was measured under a light dissecting microscope. The mean apical leakage for Group A was 1.39 mm, and for Group B 2.76 mm, whereas the mean coronal leakage for Group A was 2.87 mm, and for Group B 4.03 mm. The differences between the groups were not statistically significant (P>0.05).     

Effect of different intensity light curing modes on microleakage of two resin composite restorations

This in vitro study evaluated the marginal leakage of two resin composites light cured in four different polymerization modes. Standardized Class V cavities were prepared on the buccal enamel surface of 80 sound, freshly extracted inferior bovine incisors. The teeth were randomly divided into eight experimental groups: two resin composites (Z250 Charisma) and four polymerization modes (conventional-680 mW/cm2/30 seconds; soft start-380mW/cm2/10 seconds + 680 mW/cm2/20 seconds; plasma arc curing- 1480mW/cm(2)-3 seconds; combined- 380mW/cm2-10 seconds + 1480mW/cm(2)-3 seconds). All specimens were thermocycled (1,000 cycles at 5 degrees C and 55 degrees C) with a dwell time of one minute at each temperature and immersed in a 2% methylene blue solution for more than 12 hours. The specimens were then washed and prepared for spectrophotometric analysis to quantify the dye concentration. Soft start and combined polymerization modes presented better results and were statistically different from conventional and plasma arc curing polymerization methods for both resin composites. There were no statistical differences between the two resin composites.     

三种分层充填方法对牙本质黏结强度的影响

目的:对比研究3种分层充填方法对牙本质黏结的微拉伸强度的影响。方法:选取因正畸需要拔除的前磨牙15个,随机分为3组。去除面釉质,暴露平的牙本质表面,在其中央制备3.5mm×3.5mm×3mm的盒形洞。使用Single Bond黏结剂,按使用说明进行牙本质黏结,用Z100复合树脂充填窝洞:A组:分3层水平充填;B组:分3层斜向充填(第一层水平充填,第二、三层近远中向斜向充填);C组:分3层斜向充填(第一、二层近远中向斜向充填,;第三层水平充填)。用硬组织切片机将实验牙切成黏结面积约0.9mm×0.9mm的正方形小条作为试件,用以测试牙本质微拉伸黏结强度。在体视显微镜和扫描电镜下观察样本的断裂界面。结果:C组的微拉伸黏结强度测试值(31.99±5.27)高于A组(24.56±4.90)和B组(31.19±3.90),3种分层充填方法对牙本质微拉伸黏结强度的影响有统计学意义(P<0.05)。体视显微镜和扫描电镜下观察测试样本的断裂多数为黏结界面破坏。结论:3种分层充填方法对牙本质黏结的微拉伸强度存在影响,其中C组的分层充填方法略优于另外两组。因此,在修复较深的牙体缺损时,采用合适的分层充填方法有利于获得良好的黏结效果。     

不同根管封闭剂对根管充填封闭性能的比较研究

目的:评价3种根管封闭剂的根尖和冠方封闭性能.方法:收集新鲜拔除的人恒前牙60颗,用手用镍钛锉预备后随机分为A、B、C 3个实验组即为Cortisomol封闭剂、AHplus封闭剂加牙胶尖侧压充填,GattaFlow加主尖充填(每组20颗).根充后用印度墨汁染色、脱矿、脱水、制成透明,在体视显微镜下测量染料渗入根管的长...     

Dynamic thermomechanical properties and sorption characteristics of two commercial light cured dental resin composites.

OBJECTIVES: The first objective of this work is the study by DMTA of viscoelastic properties (E', E', tandelta, Tg) of two current dental resin composites Tetric EvoCeram (nanohybrid) and Heliomolar (microfilled) in dry condition and in water for up to 30 days. The second objective is to determine the sorption characteristics of these composites in water and ethanol/water solution 75vol.%. METHODS: For DMTA the bar-shaped specimens divided into five groups of three samples each. The first group consisted of dry samples measured 1h after curing. The second and third group consisted of samples, which had been heated in air at 80+/-1 degrees C for 1 day or had been stored in distilled water at 80+/-1 degrees C for 1 day. The fourth and fifth group consisted of samples, which had been stored in distilled water at 37+/-1 degrees C for periods 1 and 7 days correspondingly. Also specimen discs (15mm in diameter and 1mm in thickness) were immersed in water or a 75vol.% ethanol/water solution at 37+/-1 degrees C. At fixed time intervals they were removed, blotted dry to remove excess liquid, weighted and returned to the liquid. This process continued for 30 days. RESULTS: The viscoelastic properties (E', E', tandelta, Tg) of the two composites treated under different conditions were recorded and compared. Also the mass uptake, diffusion coefficient, solubility and volumetric changes for immersion of composites in water and ethanol/water solution 75vol.% at 37+/-1 degrees C were determined. SIGNIFICANCE: Tetric EvoCeram a nanohybrid composite with similar about resin matrix with Heliomolar which is a microfilled showed better dynamic thermomechanical properties and sorption characteristics than Heliomolar.     

In vitro sealing performance of two one-step adhesive systems in cervical cavities

PURPOSE: To evaluate the effects of 1) wall grinding status, 2) thermal stress, and 3) time of polishing on sealing performance of two one-step bonding systems in cervical cavities. MATERIALS AND METHODS: Semicircular cavities with dimensions of 3 x 3 x 1.5 mm were prepared along the CEJ of extracted human premolars. In experiment 1, the cavity walls were additionally ground with round steel diamond burs (regularly ground) or finished with superfine diamond burs. The cavities were treated with AQ Bond (AQ) or One-up Bond F (OB) and filled with a resin composite. Then thermocycling (5 degrees C to 55 degrees C, 1000 x) was performed. In experiment 2, the regularly ground cavities were used. After restoration, the teeth were subjected to thermocycling (1,000 to 5,000 x). In experiment 3, the restorations in the regularly ground cavities were polished immediately or 24 h after filling. No thermocycling was carried out in this group. All specimens were immersed in a dye solution for 2 h. Microleakage at coronal and apical walls was evaluated on the longitudinal sections of the restorations. RESULTS: For OB, the cavities finished with superfine burs exhibited more microleakage at the coronal wall than the regularly ground cavity (p < 0.05). The leakage at the coronal walls increased with the number of thermal cycles for both systems (p < 0.05). The delayed polishing generated better adaptation at the apical wall of AQ and at the coronal wall of OB (p < 0.05). CONCLUSION: Grinding status, thermocycling, and time of polishing had influences on the sealing performance of the two one-step adhesive systems.     

Microleakage of resected MTA

Forty-six single rooted extracted human teeth were used in this study. After cleaning and shaping, twenty canals were randomly selected for obturation with MTA placed in an orthograde manor (Group 1). Another twenty roots were obturated with gutta-percha and Kerr EWT sealer, using warm vertical compaction (Group 2). The apical 3 mm of each root in both groups were resected at approximately 45 degrees to its long axis. The teeth were aged for 48 h in a humidor. The root-ends of the teeth in Group 2 were then prepared and received MTA as a root-end filling material to a depth of 3 mm. Six roots were used as positive and negative controls. The roots of all teeth were placed in contact with India ink for 48 h. The roots were split and examined for dye leakage. There was no discernible leakage in teeth with resected MTA or those with MTA placed as a retrograde root-end filling material. We found no significant difference in dye leakage between resected MTA (Group 1) and non-resected MTA (Group 2). Based on these results it appears that the resection of set MTA does not affect its sealing ability.     

Effect of finishing time and techniques on marginal sealing ability of two composite restorative materials

STATEMENT OF PROBLEMS: Finishing of composites may adversely influence the sealing ability of direct adhesive restorations. PURPOSE: This study was conducted to determine whether finishing time and techniques under wet or dry conditions affect the microleakage of 2 types of class V composite restorations. MATERIAL AND METHODS: Eighty class V preparations were made in the buccal surfaces of noncarious molars with the occlusal margins ending in enamel and the gingival margins in dentin. Dental adhesive (Single Bond) was applied according to the manufacturer's instructions. Half of the preparations were restored with a microfilled composite (Silux Plus) and the other half with a hybrid composite (Filtek Z250). Within each major composite group (n = 40), 4 subgroups (n = 10) were established based on finishing technique (diamond finishing burs or aluminum oxide discs) and finishing time (immediate or delayed by 24 hours). The specimens were stored for 24 hours in 37 degrees C water, thermocycled for 250 cycles between 5 degrees C and 55 degrees C, immersed in 2% methylene blue solution for another 24 hours, and sectioned longitudinally. For both enamel and dentin margins, dye solution penetration at the tooth/composite interface was scored from 0 to 4 under stereoscopy at original magnification x 20. Data were analyzed with the Kruskal-Wallis test (P<.05). RESULTS: Significantly lower leakage scores were recorded for teeth restored with microfilled composite and finished under wet conditions after 24 hours (P<.01). No significant differences were found among the hybrid composite groups. CONCLUSION: For microfilled composite restorations on dentin margins, delayed wet finishing with diamond burs resulted in significantly lower microleakage scores than all other finishing protocols. Hybrid composite restorations had equivalent levels of microleakage regardless of the finishing method.     

Flowable composites as "filled adhesives:" a microleakage study

OBJECTIVE: The purpose of this in vitro study was to investigate the microleakage at dentin margins of a flowable resin composite associated with an adhesive, either light cured separately or co-cured, in Class V cavities. MATERIALS AND METHODS: Twenty four recently extracted human molars were prepared with standardized box-shaped Class V cavities of 3.0 mm (mesial-distal), 2.0 mm (occlusal-gingival), and 2.0 mm depth with margins located on enamel and dentin/cementum on the buccal or lingual surfaces. The cavities were randomly assigned into three groups (n=8): Group I - Single Bond + Filtek Z250 (control); Group II - Single Bond + Filtek Flow (light cured separately) + Filtek Z250; and Group III - Single Bond + Filtek Flow co-cured (light cured simultaneously) + Filtek Z250. After being immersed in tap water for 24 h, the specimens were thermocycled (1000x, 5 degrees -55 degrees C, 30 sec dwell time) and immersed in a 0.5% basic fuchsine solution for 24 h. The restorations were sectioned longitudinally and gingival margins were evaluated for microleakage using a 0-4 scale. Data were subjected to the Kruskal-Wallis test at p<0.05. RESULTS: A statistically significant difference at p = 0.0044 between Groups 1 and 3 and Groups 2 and 3 was observed. Although Group 2 performed slightly better than Group 1, no significant difference was observed. CONCLUSION: The use of a flowable resin composite cured simultaneously with an adhesive yielded the worst results in this study. As no statistical differences were seen between Groups 1 and 2, the use of a flowable composite as a means of minimizing microleakage at dentin margins may be questioned.     

Influence of flowable composite lining thickness on Class II composite restorations

This in vitro study aimed to investigate the influence of flowable composite lining with different thicknesses on the marginal quality and internal porosity of Class II composite restorations. Thirty-two intact molars, each prepared with two box-only Class II cavities, were randomly divided into four groups: Group 1, P60 filling alone; Group 2, ultrathin flowable composite lining/co-cured with overlaying composite; Group 3, thin lining/pre-cured and Group 4, thick lining/pre-cured. The teeth were then thermocycled for 1500 cycles (between 5 degrees C and 60 degrees C) and dye immersed for 24 hours. Exterior surface replicas of these restorations were fabricated before and after thermocycling and examined by SEM to evaluate percentages of the five marginal patterns. Data was statistically evaluated using one-way ANOVA test. The teeth were subsequently sectioned longitudinally. The interface microleakage of cervical margin was measured as to the extent of dye penetration. Internal voids were separately recorded in the cervical interface and the cervical and occlusal halves of the restorations. Mann-Whitney test was applied to analyze the interface microleakage and internal voids. Results revealed that replicas of Group 4 presented the highest percentage of marginal openings both before and after thermocycling in SEM examination. Group 2 exhibited superior marginal quality in interface microleakage evaluation compared to the other groups, while Group 4 exhibited the worst. The pre-cured groups (Group 3 and 4) showed significant reduction in interface and cervical voids. Despite the reduction in interface voids, a thick lining may impair the marginal sealing, especially after thermocycling. It was concluded that a minimally thin flowable composite lining improved cavity adaptation and marginal sealing.     

A quantitative method of measuring the microleakage of thermocycled or non-thermocycled posterior tooth restorations

This study quantified microleakage in restorations made with three packable resin composites-Solitaire, SureFil and P60; one hybrid resin composite-Z250 and an amalgam-Dispersalloy, with or without the thermocycling process. Sixty sound, freshly extracted human molars were sectioned mesiodistally, creating buccal and lingual blocks. One hundred blocks with the flattest surface were selected. Cylindrical cavities with a diameter of 1.85 +/- 0.05 mm and a depth of 1.5 mm were prepared with a special diamond bur. The blocks were randomly assigned to 10 test groups (n = 10): five restorative materials and two thermal stress groups (thermocycled groups at 3,000 cycles at 5 degrees C and 55 degrees C with a dwell time of one minute at each temperature, or non-thermocycled). After the thermocycling test, the samples were immersed in 2% methylene blue for 12 hours. The samples were ground and the powder prepared for analysis in an absorbance spectrophotometer. All the results were statistically analyzed by the Kruskal-Wallis test and the Mann Whitney test. For the non-thermocycled groups, the means (microg/ml) of microleakage were: Amalgam-4.279 (a); Solitaire-4.148 (ab); Z250-3.418 (abc); P60-3.184 (bc); SureFil-2.890 (c). For the thermocycled groups, the means were: Amalgam-7.572 (a); Solitaire-5.471 (a); Z250-4.330 (ab); P60-3.418 (bc) and SureFil-2.779 (c). Thermocycling analysis showed no significant differences between the thermocycled and non-thermocycled groups for each material tested. It was concluded that no test material prevented microleakage. Only SureFil and P60 showed leakage means significantly lower than amalgam, with SureFil showing lower leakage than Solitaire. P60 only showed lower leakage than Solitaire in the thermocycled groups and Z250 showed results similar to the others materials.     

Effect of different dye solutions on the evaluation of the sealing ability of Mineral Trioxide Aggregate

Alkaline materials have shown incompatibility with methylene blue dye in leakage experiments. The goal of the present study was to analyze the effect of different dyes on the evaluation of the apical sealing ability of Mineral Trioxide Aggregate root-end fillings. Fifty-six extracted human canines were submitted to root canal instrumentation and obturation. After apical resection, retrograde cavities were prepared and teeth were randomly divided into four experimental (n = 13) and two control groups (n = 2). The following root-end filling materials were used: groups 1 and 2--Pro Root MTA (Dentsply), groups 3 and 4--zinc oxide-eugenol cement (ZOE). Teeth in groups 1 and 3 were immersed in 2% methylene blue solution, while teeth in groups 2 and 4 were immersed in 0.2% rhodamine B in a reduced pressure environment for 48 hours. Teeth were then longitudinally sectioned and leakage was evaluated. Results were submitted to statistical analysis (ANOVA and Tukey's test). Group 1 presented the least leakage (p < 0.05). It was concluded that the evaluation of the sealing ability of MTA is influenced by the dye used, since this material presented better sealing ability when evaluated with Methylene Blue, but was similar to ZOE when evaluated with rhodamine B.     

The effect of two different polishing techniques on microleakage of new composites in Class V restorations

AIM: The purpose of this study was to investigate the effect of polishing systems on the microleakage of a nanofill, a nanohybrid, and a microhybrid composite in Class V cavities. METHODS AND MATERIALS: Preparations were made at the cemento-enamel junction (CEJ) of 36 extracted human premolars. The teeth were randomly divided into three groups and restored with new resin composites according to the manufacturers' instructions as follows: Group 1, Filtek Supreme & Single Bond; Group 2, Grandio & Solobond; and Group 3, Artemis & Excite. The restorations were finished with diamond finishing burs. The restored/finished teeth were randomly divided into two groups and polished using the following systems: Super-Snap (Al2O2 coated, abrasive disc system, fine grit, and extra fine grit) and Astropol/Astrobrush (silicon-based abrasive polisher point and polisher brush). All specimens were thermocycled 1000 times with a 10 second dwell time. They were immersed in 0.5% aqueous basic fuchsin dye for 24 hours and then sectioned buccal-lingual-longitudinally through the center of both restorations of each tooth and evaluated under a stereomicroscope at 30X magnification. The degree of dye penetration was quantified. RESULT: No significant difference in leakage scores was observed in enamel margins (p=0.456, Kruskall Wallis test), but dentin margins were significantly affected by the different polishing systems (p=0.037, Kruskall Wallis test). The lower leakage scores were recorded for Astropol/Astrobrush polishing systems. The nanofill composite showed the least leakage among the test groups in this study. The most leakage was observed in nanohybrid composite resin (p<0.05, Mann Whitney U test). CONCLUSIONS: Under the conditions of this in vitro study: the microleakage resistance of composites at enamel margins is not significantly affected by the different polishing systems; the lowest leakage scores were recorded for Astropol/Astrobrush polishing techniques in different types of composites; and the ranking of the composite materials from most to least leakage at the dentin margins according to polishing techniques was Grandio >Artemis > Filtek Supreme.     

A comparison of techniques for assessment of coronal dye leakage.

This study was designed to compare different techniques for coronal dye leakage testing. One hundred and fifty extracted human anterior teeth were fully instrumented and randomly divided into two experimental groups of 60 teeth each, plus two groups of 15 teeth each for positive and negative controls. One group was rinsed with 5.25% NaOCl (smear layer intact), whereas the other group was flushed with 17% EDTA and 5.25% NaOCl (smear layer removed). Roots were obturated with gutta-percha using lateral condensation and AH Plus as root canal sealer. Each experimental group was divided into three subgroups of 20 teeth each for three methods of testing coronal dye leakage: passive dye penetration, penetration with vacuum applied, and fluid filtration methods. The teeth were left in 100% humidity at 37 degrees C for 5 days before being immersed in Indian ink for 2 days and cleared. The linear extent of dye penetration was measured. Mean depth of leakage for the groups with the smear layer intact was 2.5 +/- 1.0 mm for passive dye penetration, 6.7 +/- 2.8 mm for vacuum dye penetration, and 3.0 +/- 1.1 mm for fluid filtration dye penetration. In the group in which the smear layer was removed, the mean depths of leakage were: 3.2 +/- 2.1 mm for passive dye penetration, 5.8 +/- 2.8 mm for vacuum dye penetration, and 3.4 +/- 2.1 mm for fluid filtration. The vacuum method resulted in significantly (p < 0.05) more dye penetration than fluid filtration and passive dye penetration. The presence or absence of smear layer had no statistically significant effect (p > 0.05) on any of the leakage testing techniques.     

Sealing ability of sectional injection thermoplasticized gutta-percha technique with varying distance between needle tip and apical foramen.

The purpose of this investigation was to evaluate the influence of the distance of the needle tip from the apical foramen on the apical seal and the length control of the root filling material when thermoplasticized gutta-percha is injected using a sectional injection technique. Ninety-nine human single-rooted mandibular incisors and permanent premolars with straight canals were divided into three equal Groups A, B and C. In Group A the teeth had relatively the wider root canal, in Group C the narrowest, while in Group B root canal size was intermediate. The root canals of all teeth were prepared with a step-back technique. Roots of Group A were instrumented to a Size 70 4 mm short of the working length, while roots of Groups B and C to a Size 70 6 mm and 8 mm short of the working length, respectively. The teeth of all groups were covered with aluminium foil and embedded in acrylic blocks. After the placement of sealer (Roth 811) the root canals of all teeth were obturated with injection-molded thermoplasticized gutta-percha using a three-stage sectional technique. The roots remained in India ink for three days and then cleared by successive immersion in nitric acid, ascending grades of alcohol and finally in xylene. The linear dye penetration and the linear apical underextentionion of the root canal filling were measured by two independent examiners under a stereo microscope. There was no significant difference in the linear dye leakage between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Restoration interface microleakage using one total-etch and three self-etch adhesives

This study evaluated the efficacy of a total-etch and three self-etch adhesives in reducing microleakage after three months water storage and thermocycling. Thirty freshly extracted caries-free human premolars and molars were used. Class V standardized preparations were performed on the facial and lingual surfaces, with the gingival margin placed 1 mm below the CEJ. The teeth were randomly divided into four groups; Group I: Xeno III one-step self-etch adhesive (Dentsply/Caulk), Group II: Prime & Bond NT total-etch adhesive (Dentsply/Caulk), Group III: i-Bond one-step self-etch adhesive (Heraeus Kulzer) and Group IV: Clearfil SE Bond two-step self-etch adhesive (Kuraray Medical). The teeth were restored using 2 mm increments of shade A2 resin composite (Esthet-X, Dentsply/Caulk). Each layer was cured using the Spectrum 800 curing light (Dentsply/Caulk) for 20 seconds at 600mW/cm2. The teeth were stored in distilled water for 90 days. Samples were thermocycled 500x between 5 degrees C and 55 degrees C with a dwell time of 30 seconds, then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margins under a stereomicroscope at 20x magnification. Dye penetration was scored: 0 = no penetration; 1 = partial dye penetration along the occlusal or gingival wall; 2 = dye penetration along the occlusal or gingival wall; 3 = dye penetration to and along the axial wall. A Mann-Whitney test was used to demonstrate significantly more dye penetration in Group III than in the other groups at both the occlusal and gingival scores (p < 0.0001). When comparing the occlusal and gingival scores for each group, the Wilcoxon Rank test showed no significant difference in dye penetration for Xeno III (p > 0.05), Prime & Bond NT (p = 0.059) and I Bond (p = 0.083), and Clearfil SE Bond yielded more dye penetration at the occlusal than at the gingival wall (p = 0.001).