The effect of flowable resin composite on microleakage in class V cavities

This in vitro study investigated the microleakage of flowable resin composite as a restorative material and as a liner (either light cured separately or co-cured with hybrid resin composite) in Class V cavities. A light-cured hybrid resin composite was used as a control. Twenty extracted human premolars were prepared with standardized Class V cavity outlines on the buccal and lingual surfaces. The occlusal margin of the cavities was on enamel and the gingival margin was on dentin. One bottle adhesive system (Single Bond) was used after etching enamel and dentin with 34.5% phosphoric acid for 15 seconds. The cavities were randomly divided into four groups of 10 each and restored according to the manufacturers' instructions: Group I-Hybrid resin composite (Z100); Group II-Flowable resin composite (Filtek Flow); Group III-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); light cured separately; Group IV-Flowable resin composite (Filtek Flow)+Hybrid resin composite (Z100); co-cured. The samples were thermocycled 200 times with a 30-second dwell time. They were then immersed in a 0.5% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney U tests. The results of this study indicate that there was no leakage at the occlusal margin for either restoration. Statistically significant differences were found among the groups at the gingival margin. No statistically significant difference was observed between the occlusal and gingival margins except in Group IV. The combination of flowable resin composite and hybrid composite light cured separately yielded the best result in this study. The most leakage was observed when this combination was co-cured. The resistance to microleakage of flowable resin composite as a restorative material is similar to that of hybrid resin composite.     

Polymerization shrinkage and microleakage in Class II cavities of various resin composites

This study investigated the polymerization shrinkage of restorative materials and microleakage in the proximal box of Class II restorations. Twenty caries free extracted human molars were prepared on the mesial and distal, making 40 slot cavities. Groups (n=10) were classified as: Group 1: Single bond/Filtek Z-250; Group 2: Single Bond/Filtek Flow/Filtek Z-250; Group 3: Admira Bond/Admira; Group 4: Ariston Liner/Ariston. Dentin bonding systems and resin composites were applied according to the manufacturer's instructions. The specimens were stored in distilled water for one week at 37 degrees C, thermocycled (5 degrees-55 degrees C x 2000), stained with 50% aqueous silver nitrate, immersed in a diluted developer solution (24 hours), rinsed and sectioned in two pieces with a low speed saw (Isomet). Dye penetration (Score 0-4) was determined separately at the occlusal enamel margin and cementoenamel junction. The volumetric polymerization shrinkage of materials was determined with the apparatus of Watts and Cash (Watts Cash, 1991) for 300 seconds. Polymerization shrinkage results were as follows: Filtek Flow (3.5% +/- 0.1) > Admira (2.1% +/- 0.1) = Ariston AT (2.3% +/- 0.1) > Filtek Z-250 (1.8% +/- 0.1) (One-way Anova, post hoc Bonferroni test at p = 0.05 level). No statistical difference was found at the enamel margins for any of the materials (Score 0-1). At the cemento-enamel junction, all test groups showed significantly higher microleakage when compared to the enamel margins (Kruskal-Wallis test, Mann-Whitney U). Dye penetration results at dentin were as follows: Filtek Flow + Filtek Z-250 = Admira < Ariston AT = Filtek Z-250. microleakage than the ion-releasing and hybrid composites lined only with bonding agent at the cementoenamel junction in Class II cavities.     

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 liner and margin location on microleakage of conventional and packable class II resin composites

This in vitro study evaluated gingival wall microleakage in packable and microhybrid conventional composite restorations with and without a flowable composite liner. Each group was evaluated with gingival margins situated in both enamel and cementum/dentin. Two hundred and forty Class II cavities were prepared in extracted third molars, half with gingival margins in enamel and half with margins in dentin/cementum. In groups of 30, restoration was undertaken with packable alone (3M Filtek P60), conventional alone (3M Z250), packable plus flowable liner (3M Filtek Flow) and conventional plus flowable liner. All used 37% phosphoric acid etch and Scotchbond 1 (3M) as the bonding system. After restoration, the teeth were thermocycled (between 5 degrees C, 37 degrees C and 60 degrees C) 1,500 times, soaked in 0.1% methylene blue, sectioned and microleakage from the gingival margin scored. Statistical analysis was performed using Kruskal Wallis and Mann-Whitney U tests. There was no significant difference between systems in terms of leakage scores when gingival margins were situated in enamel (p=0.70). All restorations with margins in cementum/dentin leaked significantly more than those with margins in enamel (p<0.001). There was no significant difference between leakage scores of 3M Z250 and Filtek P60 with cementum/dentin gingival margins (p=0.68). Use of a flowable composite liner (3M Filtek Flow) against cementum/dentin was associated with increased microleakage (p<0.001). In this study, leakage scores suggest that gingival margins should be placed in enamel. The conventional and packable resin composites tested were not associated with differences in microleakage. Leakage data do not support the use of flowable resin composite linings in Class II resin composite restorations.     

Composite restorations: influence of flowable and self-curing resin composite linings on microleakage in vitro

This in vitro study evaluated the microleakage at enamel (occlusal) and dentin (gingival) margins of MOD resin composite restorations made with different incremental insertion techniques. MOD cavities were prepared on 60 extracted human molars with the proximal margins placed 1 mm below the cemento-enamel junction. All teeth were acid-etched and treated with One-Step adhesive, then restored with a hybrid resin composite (Renew) with and without a flowable composite (AEliteflo) or a self-curing composite (Bisfil 2B) as the first increment in the proximal boxes. The time of placement of the second increment in relation to curing of the first increment was also varied. After polishing, the teeth were soaked in 0.5% basic fuchsin for 24 hours, sectioned and evaluated for dye penetration. None of the restorative techniques prevented microleakage at the enamel and dentin margins. However, microleakage at dentin margins were significantly reduced by the use of a flowable composite as the first increment in the proximal boxes. Time of placement in relation to curing had no influence on microleakage. Microleakage was lower at enamel margins than at dentin margins; however, besides microleakage at the enamel-restoration interface, 37 of the 60 restored teeth (62%) displayed at least one white line in enamel adjacent to the composite restoration.     

Microleakage of different resin composite types.

OBJECTIVE: The purpose of this study was to evaluate the microleakage of Class V cavity preparations restored with three different types of resin composite and an ormocer. METHOD AND MATERIALS: Forty Class V cavities were prepared in buccal and lingual surfaces of 20 recently extracted molar teeth. The occlusal margin of each restoration was on enamel and the gingival margin on dentin. Teeth were randomly assigned to four groups of 5 teeth each and restored as follows: Group I, flowable resin composite (Tetric Flow); Group II, hybrid resin composite (Z100); Group III, packable resin composite (Solitaire 2); Group IV, organically modified ceramics-ormocer (Admira). In all groups, the manufacturers' instructions were strictly followed. All restorative resin composite materials were placed in one increment. All teeth were then immersed in 0.5% basic fuchsin solution for 24 hours after thermocycling (200 cycles; between 4 degrees C to 60 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests. RESULTS: No statistically significant differences in microleakage were observed between groups either on enamel or dentin. CONCLUSION: All restorative materials demonstrated equal effectiveness in reducing microleakage.     

The leakage of Class II cavities restored with packable resin-based composites

Recently, new resin-based composites, called "packable" or "condensable" resin composites, are being promoted as amalgam alternatives. The purpose of this study was to evaluate leakage in Class II cavities restored with the five packable resin-based composites. On 45 freshly extracted human molars, cavities were prepared following a standardized pattern in which the Class II cavity had a length of 3.0 mm, width of 2.0 mm, and depth of 1.5 mm occlusally. The proximal box had an axial depth of 1.5 mm and a buccolingual width of 4.0 mm. The cervical margin was located 1.0 mm below the cement enamel junction (CEJ). The teeth were randomly divided into five groups of 8 each. The cavity surface was conditioned with 36% phosphoric acid, rinsed, excess water removed, and a dental bonding adhesive (Prime&Bond NT) was used for all the cavities. The teeth were then restored according to the manufacturer's instructions: Group 1, Surefil; Group 2, Solitaire; Group 3, Alert; Group 4, Filtek P60; and Group 5, Prodigy Condensable. After the restorations were completed, the specimens were finished and polished with an aluminum-oxide-coated disc, thermocycled, stained, sectioned, and viewed under a stereomicroscope for leakage at occlusal/enamel and gingival/dentin margins. All test groups showed that leakage of gingival/dentin margins were greater when compared with leakage of occlusal/enamel margins. At the occlusal/enamel margins, there were no significant differences between the materials; however, at gingival/dentin margins, Filtek P60 and Prodigy Condensable demonstrated less leakage, while Solitaire demonstrated greater leakage.     

The effect of fiber placement or flowable resin lining on microleakage in Class II adhesive restorations

PURPOSE: The aim of this in vitro study was to evaluate the effect of two fibers (polyethylene or glass) and a flowable resin liner on microleakage in Class II adhesive restorations. MATERIALS AND METHODS: Class II adhesive cavities were prepared on mesial and distal surfaces of 40 extracted sound human molars. The cavity margins were below or above the CEJ. The teeth were randomly divided into four groups according to the restoration technique: group 1: restored with a resin composite (AP-X, Kuraray) in bulk after SE Bond (Kuraray) treatment; group 2: flowable resin liner (Protect Liner F, Kuraray) was used before composite restoration; in group 3, a polyethylene fiber (Ribbond) and in group 4, a glass fiber (everStick NET, StickTech) was placed into the bed of flowable resin before composite restoration. Samples were finished, stored in distilled water for 7 days at room temperature, and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. After sealing the apices, the teeth were varnished within 1 mm of the margins and placed in 0.5% basic fuchsin dye for 24 h at 37 degrees C. After rinsing, the teeth were sectioned longitudinally through the restorations and microleakage was evaluated with a stereomicroscope. Marginal penetration was scored on a 0 to 4 scale, and the data were statistically analyzed using Kruskal-Wallis and the Mann-Whitney U-test. RESULTS: Flowable resin, everStick NET, and Ribbond THM used in combination with flowable resin significantly reduced leakage at occlusal margins in cavities with enamel margins (p < 0.05). When the leakage values on cervical dentin margins were evaluated, there was no statistically significant difference among the tested groups (p > 0.05). CONCLUSION: Use of flowable composite alone or in combination with polyethylene or glass fibers reduces occlusal leakage in Class II adhesive cavities with enamel margins.     

Effect of flowable composite lining on microleakage and internal voids in Class II composite restorations

PURPOSE: The aim of this study was to determine the influence of four flowable composite linings on marginal microleakage and internal voids in Class II composite restorations with the margins above the cementoenamel junction (CEJ). MATERIALS AND METHODS: Class II cavities were randomly divided into 8 groups (n = 10). Group 1: One Step Plus/Aelite LS Packable; group 2: One Step Plus/Aelite Flow/Aelite LS Packable; group 3: Comfort Bond/Solitaire 2; group 4: Comfort Bond/Flowline/Solitaire 2; group 5: Solobond M/Grandio; group 6: Solobond M/Grandio Flow/Grandio; group 7: Admira Bond/Admira; Group 8: Admira bond/Admira Flow/Admira. After restoration, all teeth were stored for 24 h, thermocycled (at 5 degrees C to 55 degrees C) 500 times, and soaked in 0.5% basic fuchsin dye for 24 h. After soaking, the teeth were sectioned and observed under a stereomicroscope. Gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Mann-Whitney U- and Kruskal-Wallis tests (p < 0.05). RESULTS: Statistical analyses indicated that the use of flowable resin composites provided a reduction in microleakage in groups 6 and 8. Groups 2 and 4 showed fewer voids in the cervical area than without flowable composites. CONCLUSION: It was concluded that none of the materials tested was able to eliminate the marginal microleakage on the cervical wall. Flowable resin composites under nanohybrid (group 6) and ormocer (group 8) composites provided a significantly different reduction in microleakage compared to restorations without flowable liners. Fewer cervia voids were observed in packable composites with flowable liner (groups 2 and 4) than without flowable liner (groups 1 and 3s).     

Microleakage of posterior packable resin composites with and without flowable liners

The use of flowable composites as liners in Class II packable composites has been suggested by some manufacturers. However, the contributions of this technique are unproven. This study evaluated marginal microleakage in Class II packable composite restorations with and without the use of a flowable composite liner. A conventional microhybrid composite was used as a control. Microleakage at occlusal and gingival margins of Class II cavities was evaluated using 45Ca and autoradiographs. Fifty non-carious, restoration-free human molar teeth were used. Separate mesio-occlusal and disto-occlusal Class II cavity preparations were made in each tooth. Gingival margins of all cavities were placed 1 mm apical to the cementoenamel junction (CEJ). Four Packable composites (Alert, Surefil, Pyramid and Solitaire) and one conventional microhybrid composite (Renew) with their respective manufacturer's bonding agents were used to restore the cavities. One side of each tooth was restored with composite alone, while the other side was restored with the composite lined with that manufacturer's flowable liner. The restored teeth were thermally stressed and 45Ca was used to evaluate microleakage. Two independent evaluators scored leakage based on the autoradiographs. The results showed flowable composites helped reduce microleakage at gingival margins of Class II restorations (p < 0.05). Gingival margins had higher microleakage than occlusal margins (p < 0.05). Without flowable liners, three packable composites (Alert, Pyramid and Surefil) showed higher leakage (p < 0.05) than the microhybrid control. Only Solitaire packable composite without liner showed no significant difference in microleakage to the control (p > 0.05). Although the flowable liners help reduce microleakage, Alert and Pyramid packable composites with liners still showed higher leakage than the control (p < 0.05). Surefil and Solitaire packable composites with flowable liners showed no significant difference in microleakage (p > 0.05) to the control.     

In vivo evaluation of microleakage from composites with new dentine adhesives

The purpose of this study was to investigate microleakage in V class composite restorations with total etch versus self-etching adhesives. Experiments were conducted in vivo and were also evaluated interfacial micromorphology. Forty class V cavities were prepared on the buccal surfaces of teeth in three healthy dogs. The cavities were randomly assigned into five groups of eight teeth and restored with one of the following adhesive systems: Etch and Prime 3.0/Definite flow/Definite, Prompt L-pop/Filtek flow/P-60, Admira bond/Admira Flow /Admira, Bond 1/Flow it/Alert, Stae/Wave/Glacier. After 60 days the animals were killed and the teeth were extracted. The teeth were then immersed in a solution of 0.5% basic fuchsin dye for 24 h, sectioned and scored for microleakage. Features of the tooth/restoration interfaces were also examined using Scanning electron microscopy. Student-Newman-Keuls and one-way anova revealed significance differences among the groups for overall wall scores (P < 0.05). The total-etch adhesives revealed significantly less microleakage scores than the self-etching adhesive systems tested. Wilcoxon Signed Ranks Test revealed significant differences between the occlusal and gingival microleakage scores for each adhesive restorative system, with the exception of Admira (P < 0.05).     

An in vitro comparison of marginal microleakage of alternative restorative treatment and conventional glass ionomer restorations in extracted permanent molars

PURPOSE: The objective of this study was to compare the marginal leakage of cervical restorations made using alternative restorative treatment (ART) and conventional glass ionomer restorations. METHODS: Sixteen permanent maxillary and mandibular first and second molars extracted for periodontal reasons with Class V carious dentin on the buccal surfaces were prepared using ART while a second set of 29 noncarious molars had Class V preparations made with a high-speed handpiece. The occlusal margin was located in the enamel, and the gingival margin was located in the dentin/cementum. All teeth were restored with glass ionomer cement (GIC). The teeth were thermally stressed for 300 cycles and stained with methylene blue. Samples were sectioned and evaluated for microleakage. RESULTS: One-way analysis of variance on ranks revealed no significant difference in leakage at both the dentin and enamel margins between the conventional and ART groups. The microleakage at the dentin margin, however, was significantly greater (P < .001) than at the enamel margins in the conventional group. CONCLUSION: Alternative restorative treatment with GIC provides enamel and dentin margins that show comparable marginal leakage to conventionally restored permanent teeth. For the conventional restorations, leakage at the dentin margins occurs to a significantly higher extent than at the enamel margins.     

Effect of pulp pressure on the micropermeability and sealing ability of etch & rinse and self-etching adhesives

This research evaluated the effect of pulp pressure on the micropermeability and sealing ability of etch & rinse and self-etching adhesives. Two etch & rinse adhesives (Prime&Bond NT and Admira Bond) and one self-etching adhesive (Xeno III) were used. Adhesive layer micropermeability was evaluated by using confocal laser scanning microscopy (CLSM). Eighteen molars were connected to a pulp pressure device and divided into two groups. One group was restored with pulp pressure and the other group without. Each group was divided into three subgroups according to the adhesive used. The adhesives were rhodamine-labeled and Class V cavities were restored. After restoration, all specimens were kept under pulp pressure conditions for 24 hours with fluorescein-labeled pulp fluid. The specimens were sectioned and the axial wall was observed under CLSM. A microleakage test was performed to evaluate the sealing. Thirty molars were divided into two groups. One group was prepared with a pulp pressure device and the other group without. Each group was divided into three subgroups as a function of the adhesive used. Class V cavities were restored and the specimens were immersed in fuchsin and sectioned. Microleakage and dentin penetration were recorded in the occlusal and gingival walls. A CLSM study showed that the etch & rinse adhesives had higher micropermeability compared to the self-etching adhesives and pulp pressure made all the adhesives more permeable. In the occlusal wall, the best sealing (hermetic) was obtained when etch & rinse adhesives were used. Xeno obtained the lowest occlusal sealing values. In the gingival wall, Xeno obtained the best sealing, followed by Admira and Prime&Bond. Pulp fluid decreased gingival wall sealing when etch & rinse adhesives were used but not when self-etching adhesive was used.     

Influence of resin composite shade and location of the gingival margin on the microleakage of posterior restorations

OBJECTIVE: The objective of this in vitro study was to evaluate the influence of resin composite shade and location of the gingival margin (enamel or dentin) on the microleakage of proximal restorations on posterior teeth. Methods and MATERIALS: Sixty freshly extracted human third molars were prepared with standardized Class II box-shaped cavities with proportional size and shape, with distal gingival margins located on the enamel and mesial gingival margins on dentin. The teeth were randomly divided into 6 groups according to resin shade (n=10): G1-Incisal; G2-A1; G3-A2; G4-A3; G5-A3.5; G6-A4. The cavities were restored with a total-etch 1-bottle adhesive system and microhybrid resin composites inserted in 4 increments, light cured for 20 seconds through the occlusal surface, then an additional 60 seconds for each surface. After 1 week of immersion in distilled water, the specimens were thermocycled (500 cycles, 5 degrees -55 degrees C, 30 seconds dwell time), sealed with nail polish and immersed in 0.5% basic fuschin solution for 24 hours. The restorations were sectioned longitudinally, and microleakage was evaluated using a 0-3 score scale. RESULTS: Data were subjected to Kruskal-Wallis and Wilcoxon tests at p<0.05. No statistically significant differences between groups were observed regarding the shade of resin composite (p=0.8570). When margins (enamel or dentin) were considered separately, statistically significant differences were observed between groups (p<0.0001), with enamel margins exhibiting lower degrees of microleakage. CONCLUSION: The variation of resin composite shades utilized in this study did not influence the microleakage of Class II restorations. However, the location of the gingival margin influenced the microleakage.     

Evaluation of the cervical integrity during occlusal loading of Class II restorations

There are many concerns regarding the clinical behavior of packable composite restorations in Class II cavities, particularly when those restorations are subjected to axial mechanical loads. This study evaluated microleakage in vitro in proximal vertical "slot"-type cavities with walls located in enamel and dentin, filled with packable composite, associated or not associated with a flowable composite, a reinforced light-curing glass-ionomer or a compomer, after being submitted to occlusal load cycling. These preparations were subjected to either occlusal load cycling or no occlusal load cycling. Eighty human molars with enamel and dentin margins were treated with standardized cavity preparations (proximal vertical "slot" preparations). After completing the filling process using a packable composite (Filtek P60) with or without a cervical increment of flowable composite (Filtek flow), light-curing glass-ionomer (Vitremer) or compomer (Dyract AP), the molars were separated into two groups: control (without occlusal loading) and test, in which 4,000 one-second cycles of 150 N occlusal loading were applied. All 80 teeth were submitted to a microleakage test, then evaluated utilizing silver nitrate dye penetration. Significant statistical differences (Wilcoxon test, p<0.05) in the amount of leakage in enamel and dentin were found in both the control and test groups. After a paired comparison of the control and test groups, a significant statistical difference was found at the enamel level (Mann-Whitney test, p<0.05). In dentin, the only statistically significant difference found was the relation to the flow material. The Kruskal-Wallis test did not detect any statistically significant difference in the amount of leakage among the four materials studied, with a 5% level of significance for both enamel and dentin. Based on this data, it was concluded that restorations with margins located in dentin had greater microleakage than those restorations with margins located in enamel. When the samples were submitted to occlusal loading, they were negatively influenced, which increased microleakage values in enamel and dentin. There was no statistically significant difference among the four tested materials, when comparing their performance.     

The effect of pulse activation on microleakage of a 'packable' composite resin and two 'ormocers'

The purpose of the study was to examine the effect of pulse polymerization on microleakage of one packable composite resin and two organically modified ceramics (ormocers), within a high C-factor preparation. Class-V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on 60 freshly extracted premolars or molars. Teeth were randomly assigned to 12 experimental groups (five teeth each) representing the different restorative systems, mode of polymerization and thermal cycling test. Three groups of 20 teeth each were restored with one of the following restorative systems: Scotch bond 1/Filtek P 60, Admira bond/Admira, Etch&Prime 3.0/Definite. 10 restorations of each restorative system (two experimental groups) were conventionally polymerized, whereas the other 10 restorations were polymerized with a pulse program. The specimens were stored in double-distilled water at 37 degrees C for 24 h. Ten restorations from each restorative system (30 restorations, half of the specimens) were thermocycled, the other 30 restorations were kept in double-distilled water at 37 degrees C for 24 h. Then all 60 restorations stained with dye, sectioned and scored for microleakage. Results showed that there were no significant differences (P > 0.05) among the materials with respect to microleakage scores. The experimental groups that were conventionally polymerized revealed significantly more microleakage (P < 0.05) after thermal cycling than all the other groups. The gingival microleakage was significantly more (P < 0.05) than occlusal in conventionally polymerized, thermocycled experimental groups.     

Effects of different types of adhesive systems on the microleakage of compomer restorations in Class V cavities prepared by Er,Cr:YSGG laser in primary teeth

The aim of this in vitro study was to evaluate the effects of different types of adhesive systems on the microleakage of compomer restorations in Class V cavities prepared by erbium, chromium: yttrium scandium gallium garnet (Er,Cr:YSGG) laser. There were five test groups according to the type of adhesive applied to the cavities: Adper Single Bond 2 (Group 1), Scotchbond Multi-Purpose Plus (Group 2), Xeno III (Group 3), Clearfil Protect Bond (Group 4), Prime&Bond NT (Group 5). Dye penetration was evaluated under a stereomicroscope, and data were statistically analyzed by Kruskal-Wallis and Wilcoxon Signed Ranks tests. Gingival margins showed significantly higher microleakage than occlusal margins in all the test groups (p<0.05). Groups 1 and 2 showed significantly less microleakage than Group 5 (p<0.05), and there were no statistically significant differences among Groups 3, 4, and 5 (p>0.05). None of the dentin bonding agents eliminated microleakage completely, and higher microleakage scores were observed along the gingival margin than the occlusal margin.     

Effect of dentin deproteinization on microleakage of Class V composite restorations

The role of the collagen fibers in dentin adhesion has not clearly been established. Therefore, this laboratory study evaluated the microleakage at resin-dentin and resin-enamel interfaces of Class V composite restorations after etching enamel and dentin with phosphoric acid (H3PO4) or after etching with H3PO4 followed by deproteinization with 5% sodium hypochlorite (NaOCl) to prevent the formation of a hybrid layer. Ten extracted human molars were used to prepare standardized Class V cavities on both buccal and lingual surfaces. The teeth were randomly divided in two groups: 1) Class V cavities that were etched with H3PO4 for 15 seconds; b) Class V cavities that were etched with H3PO4 for 15 seconds followed by collagen removal with 5% NaOCl for two minutes. The cavities were restored using the Prime & Bond 2.1 bonding system and TPH resin composite. The specimens were stored in water for 24 hours at 37 degrees C and thermocycled 500 times between water baths kept at 5 degrees C and 55 degrees C. After thermocycling, specimens were immersed in a 0.5% aqueous solution of basic fuchsin for 24 hours. Three longitudinal sections of each restoration were obtained and examined with a stereomicroscope for qualitative evaluation of microleakage. The data were statistically analyzed by Mann-Whitney U and Wilcoxon matched pairs signed ranked tests. Extra specimens were analyzed with the scanning electron microscope (SEM). Occlusal margins (enamel margins) resulted in statistical lower degree of leakage than gingival margins (dentin/cementum margins) in both treatment groups. For each type of margin, there were no statistically significant differences between the etched and the etched and deproteinized groups. Under the SEM, occlusal surfaces showed no detachment between enamel and dentin, while dentin/cementum resulted in gap formation.     

Effect of multi-step dentin bonding systems and resin-modified glass ionomer cement liner on marginal quality of dentin-bonded resin composite Class II restorations

The use of resin composites in the restoration of Class II cavities with gingival margins located in dentin is still controversial. The purpose of this in vitro study was to evaluate the effect of four state-of-the-art multi-step dentin-bonding systems (A. R. T. Bond, Syntac, OptiBond DC, Scotchbond Multipurpose) on marginal adaptation and microleakage of dentin-bonded composite Class II restorations. A total of 72 Class II cavities with gingival margins in dentin were prepared in extracted molars and filled with fine-hybrid composites using a three-sited light curing technique. In one half of the cavities the pulpal wall was lined with a resin-modified glass ionomer cement liner (RM-GIC), in the other half a total bonding technique was applied. A. R. T. Bond and Syntac were tested with selective enamel etching (SE) and total etching (TE). Marginal adaptation was evaluated in a scanning electron microscope before and after thermocycling (TC). Microleakage was determined by dye penetration. After TC the proportions of continuous margin in dentin ranged from 37% (Syntac/SE) to 91.2% (A. R. T. Bond/TE). Scotchbond Multipurpose exhibited the lowest degree of microleakage (0.22 mm). Marginal enamel fracture was the most prevalent marginal defect at the enamel margins (8.3–22.2%). The use of the RM-GIC had no beneficial effect on any of the marginal parameters, either in dentin or in enamel. It is concluded that low degrees of marginal gap formation and microleakage can be achieved in totally bonded composite Class II restorations when using state-of-the-art multi-step bonding systems in combination with a meticulous incremental filling technique. Received: 6 April 1998 / Accepted: 25 August 1998     

Microleakage study of different adhesive systems in Class V cavities prepared by Er,Cr:YSGG laser and bur preparation

This study sought to compare the microleakage of composite resin restorations using two different dentin adhesive systems and two different modes of cavity preparation: a high-speed handpiece and an Er,Cr:YSGG laser. Twenty-five caries-free permanent human premolars were assigned randomly into five groups of five. A high-speed handpiece was used to prepare Class V cavities on the buccal and lingual surfaces of 10 randomly selected teeth. Class V cavities were cut on the buccal and lingual surfaces of the remaining 15 teeth using the Er,Cr:YSGG laser system. Fifty cavities were prepared with enamel and dentin margins 1.0 mm below the cemento-enamel junction and assigned into five groups: I, II, and III by the Er,Cr:YSGG laser and IV and V by the high-speed handpiece. In all groups, the differences between gingival and occlusal leakage scores were statistically significant (p < 0.05). The occlusal and gingival scores of groups I and IV demonstrated statistically significant differences (p < 0.05). The lased group with additional acid etching revealed less microleakage than groups III and IV (p < 0.05). Both self-etch and total-etch adhesive systems demonstrated acceptable microleakage scores when used on Er,Cr:YSGG laser-prepared cavities; however, additional acid etching after Er,Cr:YSGG laser preparation is recommended.