Microleakage of endodontically treated teeth restored with fiber posts and composite cores after cyclic loading: a confocal microscopic study

STATEMENT OF PROBLEM: The effectiveness of the seal obtained with carbon fiber posts and composite cores is still unclear. Both 3-step dental adhesives and self-etching adhesive primers have been suggested as adhesive systems. PURPOSE: This confocal microscopic study evaluated the microleakage of teeth endodontically treated and restored with fiber posts and composites with 3 adhesive systems. MATERIAL AND METHODS: A total of 72 human mandibular premolars were endodontically treated and divided into 6 groups of 12 teeth each. The first 3 groups were treated with an endodontic sealer containing zinc oxide-eugenol (ZOE) and restored with temporary filling materials containing ZOE. The last 3 groups were treated with ZOE-free materials. Post spaces were prepared in the root canals. The first group treated with ZOE-based materials was restored with fiber posts cemented with zinc phosphate cement and composite cores without adhesive. The other 2 groups of ZOE-treated teeth were restored with fiber posts cemented with All Bond 2 and Panavia 21 dental adhesives, respectively. The last 3 groups were restored with fiber posts cemented with All Bond 2, Panavia 21, and Panavia Fluoro cement, respectively. The teeth were loaded intermittently at 2 cycles per second in a moist environment and, after 300,000 cycles, immersed in a solution of Rhodamine B dye for 48 hours. A confocal microscope was used to observe the teeth. The ratio between the length of the interfaces observed and the length of the dye penetration was evaluated. Two teeth from each group acted as controls and were not subjected to dynamic loads. RESULTS: All resin cement groups leaked significantly less than the group cemented with zinc phosphate cement. No statistically significant difference was found between the microleakage of teeth treated with ZOE-based and non-ZOE-based materials. Teeth restored with All Bond 2 dental adhesive leaked significantly less than those restored with Panavia cement. CONCLUSION: The 3-step dental adhesive (All Bond 2) resulted in a better marginal seal than that obtained with the self-etching primers (Panavia 21 and Panavia F). The use of endodontic sealers and temporary filling materials containing ZOE had no detrimental effect on the marginal seal of carbon fiber post/composite resin core restorations.     

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

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

The walking bleach procedure: an in vitro study to measure microleakage of five temporary sealing agents

The purpose of this study was to compare the in vitro sealing capacity of five materials, each used as a temporary sealing agent for the walking bleach technique. All teeth received traditional biomechanical root canal instrumentation, after which the walking bleach agent was placed in the pulp chamber space. The occlusal access was sealed with one of five temporary materials: two hydraulic filling materials, a photoactivated resin composite, a zinc oxide-eugenol cement, and a zinc oxide phosphate cement with/without the placement of a piece of rubber sheet that was placed as a barrier to isolate filling material from the bleaching agent. All teeth were stored in a 1% solution of Alcian blue with thermal cycling stress. After 1 wk, they were sectioned longitudinally, and ranked by graded scores of 0 to 3, according to the degree of the dye penetration. Significantly less dye microleakage was observed in the two hydraulic materials than in the photoactivated resin. Both zinc oxide-eugenol and zinc phosphate cements showed a considerable amount of microleakage. There were no significant differences between the groups with and without a rubber sheet. Our data demonstrate that hydraulic filling materials provide the most favorable cavosurface seal when they are firmly packed into the cavity space to prevent microleakage.     

Microleakage of temporary endodontic restorations in overdenture tooth abutments

PURPOSE: The sealing of provisional filling material in overdenture tooth abutments during provisional rehabilitation is of primary importance to the long-term success of roots bearing gold casting copies. The aim of this in vivo study was to evaluate the microleakage of four different provisional filling materials after a period of 1 week. MATERIALS AND METHODS: Five patients needing treatment with overdenture prostheses and scheduled for the extraction of at least four teeth were chosen. After performing endodontic treatment on the roots to be extracted, a standardized cavity preparation 3 mm in depth was made using a diamond bur. Each cavity was filled with one of the four provisional materials selected for the evaluation (Cavit-W, IRM Caps, Guttapercha, Fermit-N), and the interim prostheses were delivered to the patients. After 1 week, the roots were extracted and stored for 24 hours in 0.5% basic fuchsin at 37 +/- 1 degrees C for 24 hours. Subsequently, the roots were severed and observed under a stereomicroscope for microleakage evaluation. RESULTS: The materials showed different degrees of microleakage, but none allowed dye penetration to the bottom of the cavity. IRM Caps showed the lowest mean value of dye penetration (168 microns), while Fermit-N showed the highest (1,475 microns). All materials differed from each other (P < .05). CONCLUSION: Within a period of 1 week, the materials provided acceptable to good sealing properties. All of the materials may be considered suitable for provisional fillings if they do not remain in the oral cavity for more than 1 week.     

Sealing ability of intermediate restorations and cavity design used in endodontics

Temporary filling materials are used in endodontics to prevent contamination of the root canal system during intertreatment visits. Recently, a new composition resin (TERM) has been introduced as an interim restoration in endodontics. The purpose of this investigation was to evaluate the efficacy of this resin as an interim restoration and possible effect of access cavity design with respect to its sealing ability compared with other temporary restorative materials. Sixty human teeth were divided into two categories, and two types of access cavities were prepared, namely tapered access with walls divergent toward the occlusal surface and straight access with parallel walls. The prepared teeth from each category were divided into three subgroups of ten each to receive Cavit (group I), IRM (group II), or TERM (group III). After the fillings were placed, the teeth were transferred into a humidor where they stayed for 24 hours. The teeth were then thermocycled. Each group was thermocycled for 2 hours at 1 minute intervals at 60 degrees C and 4 degrees C. Then the teeth were sealed with a compound and coated with two layers of clear varnish, with the exception of cavity margins. Each occlusal surface was immersed in a vial containing silver nitrate. The teeth were sectioned longitudinally, and the degree of dye penetration was evaluated under a dissection microscope according to set criteria. Our findings demonstrated that design of cavity preparation was not a functional parameter in leakage pattern. Results indicated that Cavit had the best sealing ability whereas IRM showed the maximum dye penetration.     

A comparative study of four coronal obturation materials in endodontic treatment.

The aim of this study was to compare, in vitro, the ability of temporary versus permanent materials to seal the access cavity. Eighty human maxillary single-canal teeth were prepared biomechanically and obturated with gutta-percha and an endodontic cement AH Plus, using the warm vertical compaction technique. All access cavities were sealed with 1 of 4 materials (Cavit, Fermit, Tetric, or Dyract). Microleakage was assessed by methylene blue dye penetration. The teeth were submitted to 100 thermocycles, with temperature varying from 0 degree to 55 degrees C. The greatest degree of leakage was observed with the temporary materials (Cavit and Fermit). There was a significant difference (p < 0.05) in leakage between all materials except between Dyract and Tetric. This suggests that it may be more prudent to use a permanent restorative material for provisional restorations to prevent inadequate canal sealing and the resulting risk of fluid penetration.     

Comparison of the sealing ability of mineral trioxide aggregate and Portland cement used as root-end filling materials

Inadequate apical seal is the major cause of surgical endodontic failure. The root-end filling material used should prevent egress of potential contaminants into periapical tissue. The purpose of this study was to compare the sealing ability of four root-end filling materials: white mineral trioxide aggregate (MTA), gray MTA, white Portland cement (PC) and gray PC by dye leakage test. Ninety-six human single-rooted teeth were instrumented, and obturated with gutta-percha. After resecting the apex, an apical cavity was prepared. The teeth were randomly divided into four experimental groups (A: white MTA, B: gray MTA, C: white PC and D: gray PC; n = 20) and two control groups (positive and negative control groups; n = 8). Root-end cavities in the experimental groups were filled with the experimental materials. The teeth were exposed to Indian ink for 72 hours. The extent of dye penetration was measured with a stereomicroscope at 16× magnification. The negative controls showed no dye penetration and dye penetration was seen in the entire root-end cavity of positive controls. However, there was no statistically significant difference among the four experimental groups (P > 0.05). All retrograde filling materials tested in this study showed the same microleakage in vitro. Given the low cost and apparently similar sealing ability of PC, PC could be considered as a substitute for MTA as a root-end filling material.     

Interface seal of incremental placement of visible light-cured composite resins

An investigation was conducted to determine the quality of seal at the interface when a visible light-cured composite resin was placed and cured in increments. Five samples of each of the following composite materials were tested: Aurafill, Command, Command Ultrafine, Durafill, Prisma-Fil, and Silux. Samples of each material were placed in a thermocycling dye bath that contained a 0.5% aqueous solution of basic fuchsin dye for 25 hours. The samples were removed from the dye bath, rinsed, dried, and prepared for examination with a x25 microscope by two examiners. Neither examiner reported dye penetration at the interface of the materials tested. These findings effectively highlight the practicality of the incremental placement of light-cured composite resins.     

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

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

A comparison of two temporary restorations: light-cured resin versus a self-polymerizing temporary restoration

Temporary restorative materials are an important component of endodontic therapy. They must both adequately seal the access preparation between visits and protect the obturated canal(s) from microleakage until a permanent restoration can be placed. The efficacy of Cavit and T.E.R.M. (a new light-cured composite product) was compared with the use of a carbon black coronal microleakage protocol. The teeth examined had previously received coronal restorations. After the teeth were accessed, restored with Cavit or T.E.R.M., and exposed to the dye, they were cleared. Three-dimensional assessment then revealed that Cavit more consistently provided an effective seal. In addition, a great deal of microleakage was observed around the permanent restoration-tooth interface. This indicates that perhaps leaking permanent restorations should be removed in their entirety before initiation of endodontic treatment.     

Light-cured glass ionomer cement as a retrograde root seal

A light-cured glass ionomer cement was investigated as a retrograde root seal, without a retrograde cavity. This was compared with the material used in a retrograde cavity, and with a conventional glass ionomer cement, as a seal. The adaptation and sealing ability of the test materials were assessed using a confocal optical microscope with a fluorescent dye. The root canals of 40 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were subsequently apicected, then divided into four equal groups. In one group, a retrograde cavity was prepared, and the light-cured glass ionomer cement was placed as a retrograde root filling. No retrograde cavities were prepared in the three remaining groups. The light-cured glass ionomer cement was applied directly onto the apicected root face. Two different thicknesses of light-cured glass ionomer cement were tested, a thin layer (≈1 mm) in one group, and a thicker layer (<1 mm) in another group. A conventional glass ionomer cement was used in the last group, and applied directly onto the root face in a single thickness (≈1 mm). In the group where the light-cured glass ionomer cement was used in a retrograde cavity, the material was often well adapted to one cavity wall, but gaps were found on the opposite wall. The light-cured and conventional glass ionomer cement retrograde root seals were well adapted to the root face, regardless of the thickness of material used. The thinly applied (≈1 mm) light-cured glass ionomer cement retrograde root seals permitted the least leakage. This was significantly less than the light-cured glass ionomer cement used with a retrograde cavity (P > 0.001). The greatest extent of dye penetration was found with the thick (< 1 mm) light-cured and conventional glass ionomer cement (≈1 mm) root seals; the differences between these were not significant. The light-cured glass ionomer cement was only suitable as a retrograde root seal when a thin layer (≈1 mm) was used.     

Microleakage between endodontic temporary restorative materials placed at different times.

Occlusal endodontic access preparations are occasionally made in teeth without removing the original restoration. However, microleakage between restorative materials that are placed at different times has not been extensively studied. Therefore, our objective was to compare microleakage at three areas: between an access opening restorative material and the cavity wall; between an additional material placed later to patch a secondary opening in the first restorative material and the original restorative material itself; and between the secondarily placed material and the cavity wall. Standard endodontic access preparations were made in 120 noncarious, nonrestored crowns of extracted human molars. These teeth were divided into six experimental groups. Another four molars were controls. The endodontic access cavities were restored with either IRM or amalgam as the primary restorative material. After 14 days, half of the primary restorations was removed, and this defect was filled with a secondary restorative material: IRM, Caviton, or a double seal of Caviton and IRM. Microleakage was measured linearly as the extent of basic fuchsin dye penetration under a stereomicroscope after thermal cycling (5 degrees and 55 degrees C for 100 cycles) and tooth sectioning. Wilcoxon signed-rank test was used for statistical analysis. Results indicated significantly less microleakage between primary and secondary restorative materials placed at different times than microleakage between primary temporary restorative materials and the access cavity wall, regardless of the type of primary restorative material used (IRM or amalgam).     

Apical sealing efficacy of two reverse filling techniques versus cold-burnished Gutta-percha

The apical seal produced by the cold-burnished gutta-percha method and two amalgam reverse filling techniques was investigated in an in vitro study using 36 extracted human single-rooted teeth. Following root canal obturation, 27 teeth were divided into three experimental groups and each group was subjected to one of the three following filling techniques: (a) cold-burnishing of gutta-percha; (b) amalgam reverse filling; and (c) amalgam reverse filling in conjunction with cavity varnish. The remaining nine teeth served as controls (4). The teeth were placed in methylene blue dye for a period of 1 wk, after which they were retrieved, washed, sectioned, and the apical dye penetration measured. The results showed that amalgam with cavity varnish demonstrated less dye penetration than the other experimental groups. The difference was statistically significant (p less than 0.0001).     

Microleakage in three designs of glass ionomer under composite resin restorations

Three Class V cavity configurations with walls above and below the cemento-enamel junction were compared when 'sandwich' technique restorations with glass ionomer and composite resin were used. No dye penetration occurred at the occlusal cavosurface margin when the latter was bevelled and light-cured Scotchbond was applied to the etched enamel before restoration with Durafil composite resin. The least dye penetration at the gingival margin was observed when Ketac bond glass ionomer covered the entire non-bevelled wall. No configuration entirely eliminated dye penetration at the gingival margin.     

Evaluation of the microleakage at the proximal walls of Class II cavities restored using resin composite and precured composite inserts.

OBJECTIVE: This in vitro study compared the microleakage of resin composite restorations placed in Class II cavity preparations using an incremental placement technique with and without the addition of precured resin composite inserts. METHOD AND MATERIALS: Sixty standardized mesio-occlusal and disto-occlusal cavities were prepared in 30 recently extracted molar teeth. Twenty cavities were restored by employing the incremental placement technique (group I), and 40 cavities were restored using the incremental placement in the presence of precured composite inserts of two sizes: 1 x 3 mm (group II) and 1.25 x 3 mm (group III). The restored teeth were thermocycled for 250 cycles in water baths set at temperatures of 5 degrees C and 50 degrees C using a 30-second dwell time, stained, and sectioned horizontally at the middle of the restoration. Following sectioning, each specimen was microscopically examined at x 4 magnification. The extent of dye penetration at the tooth/restoration interface was scored for each test group, and the scores obtained were subjected to one-way analysis of variance (ANOVA) and Tukey's pairwise comparison at a 95% significance level. RESULTS: The current investigation showed statistically significant differences in dye penetration between the three test groups. CONCLUSION: The use of precured resin composite inserts with the incremental placement technique in the restoration of Class II cavity preparations seems to improve the marginal seal of the proximal walls of finished restorations.     

流动性充填材料用于预防性树脂充填的实验研究

目的　以传统的复合树脂+窝沟封闭剂的方法为对照组,用体外实验的方法评价流动树脂、流动复合体在预防性树脂充填(preventiveresinrestoration ,PRR)治疗中的情况。方法　患小面积龋被拔除第三恒磨牙9颗,分别用流动树脂(A组)、流动复合体(B组)和传统的复合树脂材料+窝沟封闭剂(C组)的方法进行PRR治疗。5 0 %AgNO3 浸染法检查微渗漏;用SEM观察树脂与牙齿的结合情况。结果　①渗透实验表明各实验组和对照组中均存在一定程度的微渗漏;在微渗漏率方面,A组低于对照的C组(P <0 .0 5 ) ,在树脂渗透率方面A组低于B组和C组(P <0 .0 5 )。②SEM上显示A与B组相似,多数标本树脂与牙齿接触的界面上有结合良好的树脂突样结构,但树脂在和窝沟底部与牙体组织结合较差,特别在极细窝沟处;C组中结合良好的界面所占比例较少,复合树脂勉强压入窝洞后充填不实,在沟底部常见宽大裂纹。结论　在流动复合体和流动树脂在PRR治疗时更适用于沿窝沟走向侵润的窄长形态的窝沟内龋,而传统PRR法更适用于单个龋损直径在1 .5～2mm左右的圆形或卵圆形的小面积龋,流动性充填材料在PRR治疗中可作为传统法的一种补充,最大限度地保留健康牙体组织。     

Fracture strength and fracture patterns of root filled teeth restored with direct resin restorations

Objective

To compare fracture characteristics of root-filled teeth with variable cavity design and resin composite restoration.

Methods

80 extracted intact maxillary premolars were divided randomly into eight groups; (1) intact teeth; (2) unrestored MOD cavity; (3) unrestored MOD cavity plus endodontic access through the occlusal floor; (4) unrestored MOD plus endodontic access with axial walls removed; (5) MOD restored with resin composite; (6) MOD plus endodontic access, resin composite; (7) MOD plus extensive endodontic access, resin composite; (8) MOD plus extensive endodontic access, GIC core and resin composite. A ramped oblique load was applied to the buccal cusp in a servohydraulic testing machine. Fracture load and fracture patterns were recorded. Fracture loads were compared statistically using 1-way ANOVA, with Dunnett test for multiple comparisons.

Results

Unrestored teeth became progressively weaker with more extensive preparations. Endodontic access confined within the occlusal floor did not significantly affect strength compared to an MOD cavity. Loss of axial walls weakened teeth considerably [292 + 80 N vs 747 + 130 N for intact teeth]. Restoration increased the strength of prepared teeth particularly in teeth without axial walls. Teeth with a GIC core were not significantly weaker than intact teeth [560 + 167 N]. Failures were mostly adhesive at the buccal interface, with the fracture propagating from the buccal line angle of the occlusal floor (MOD and MOD plus access groups) or of the proximal box (axial wall removed).

Conclusions

Direct restorations increased fracture resistance of root filled teeth with extensive endodontic access. Both restored and unrestored teeth showed similar fracture patterns.     

几种常用及新型充填材料密合度的实验研究

目的 :为前牙及后牙充填选择合适的材料提供依据。方法 :将 75颗离体牙分为五组 ,分别充填银汞合金 ,银汞合金 +粘接剂 ,复合树脂 ,玻璃离子 ,DyractAP。所有离体牙均进行染料渗透试验 ,观察染料渗漏深度。结果 :单纯银汞合金充填渗漏率最大 ,与银汞合金 +粘接剂组渗漏率具有显著性差异 (p <0 0 1) ;复合树脂、GC及DyractAP相比 ,DyractAP密合度最好 ,三者渗漏率具有显著性差异 (p<0 0 5 )。结论 :对于后牙面充填 ,银汞合金粘接修复是首选方法。对于楔状缺损及根颈部缺损 ,以Dyract较好。     

Comparative in vivo analysis of the sealing ability of three endodontic sealers in post-prepared root canals

AIM: To compare the sealing ability of the endodontic sealers AH Plus, Sealer 26 and Endofill in premolar teeth of dogs exposed to the oral cavity after post-preparation. METHODOLOGY: Forty teeth with two canals each underwent root canal cleaning and shaping. Before filling, the canals were randomly distributed into three groups according to the sealer to be used: Group 1 - AH Plus; Group 2 - Sealer 26; and Group 3 - Endofill (Dentsply, Indústria e Comércio Ltda.). Immediately after filling, the gutta percha and sealer were partially removed from the canals, leaving material only in the apical third of the root. The teeth were temporarily sealed with glass ionomer sealer for 72 h to ensure setting. The coronal seal was then removed and the canals were exposed to the oral cavity for 45 days. The animals were euthanased and their mandibles and maxillae were removed. After abundant irrigation with distilled water, the canals were dried and filled with India ink. The teeth were sealed again for 96 h before extraction. The roots of the extracted premolars were separated and stored in labelled test tubes. The roots were cleared and the extent of dye penetration was measured with a 20x stereoscopic magnifying lens. RESULTS: Statistical analysis revealed that there were significant differences between the sealers studied (P < 0.001). Means for the extent of dye penetration for AH Plus, Endofill and Sealer 26 were, respectively, 0.13, 2.27 and 3.08 mm. CONCLUSIONS: After 45 days exposure to the oral cavity, none of the sealers was capable of preventing leakage and coronal dye penetration. There were significant differences between the sealers studied, in terms of mean dye penetration.     

Sealing of minimally invasive Class II fillings (slot) using an adhesive patch: sealant margin extension for prevention

A laboratory study was performed to assess the potential of an adhesive patch to seal small, unbeveled, Class II, box-only (slot) composite fillings. After minimal access cavity preparation with an 80 pm diamond bur, 40 box-only Class II cavities were prepared mesially and distally in 20 extracted human molars using a u-shaped PCS insert (EMS). One cavity per tooth was adhesively filled with a hybrid composite material in one increment. A patch, acting as an adhesive matrice, was applied to the other cavity of each tooth to seal the restoration. The margin of the patch was located in areas easily accessible to oral hygiene measures and self-cleaning. All the teeth were subjected to thermo-mechanical stress in a computer-controlled masticator device. In 10 teeth, caries was induced in a microbial-based artificial mouth model and quantitatively determined by confocal laser scanning microscopy. Microleakage was assessed in the other 10 teeth in two planar sections after immersion in 0.5% basic fuchsin solution. The results showed no demineralization at the filling margins protected with the patch. Microleakage was observed in one sample only and was limited to the enamel. In contrast, the margins of fillings without the patch application showed a mean demineralization depth of 146 +/- 42 microm and dye penetration into the dentin in five sections. This innovative approach to sealing restorative margins with an adhesive patch results in less leakage and filling margin demineralization and merits further investigation.