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.     

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 effect of different types of flowable restorative resins on microleakage of Class V cavities

This study evaluated the microleakage of Class V cavities restored with three different types of flowable resin restorative material and compared the effects of using their respective manufacturer's dentin adhesive or a different brand. Class V cavities with the occlusal margin in enamel and the gingival margin in dentin were prepared on the buccal and lingual surfaces of 48 non-carious human molars. The teeth were randomly assigned to three equal groups of 16. The first eight teeth in each group were restored with one of the flowable restorative materials (Filtek Flow, Dyract Flow, Admira Flow) using the manufacturer's recommended dentin adhesive (Single Bond, Prime & Bond NT, Admira Bond), and the remaining eight molars were restored using a different brand of dentin adhesive (Gluma Comfort Bond). The samples were thermocycled 200 times (5 degrees C-55 degrees C) with a one-minute dwell time. They were then immersed in a 2% basic fuchsin solution for 24 hours, sectioned and analyzed by stereomicroscopy. There was no statistically significant difference at the occlusal margins for either restoration used with its respective dentin adhesive. At the gingival margins, there was a significant difference among all groups. Flowable ormocer (Admira Flow/Admira Bond) displayed the least leakage at the gingival margins. When these flowable restoratives were used with a different brand of dentin adhesive, statistically significant differences were observed both on enamel and dentin. None of the restoratives tested fully prevented leakage at the gingival margins. No significant differences in microleakage were observed among the restorative materials used with respect to the manufacturer's dentin adhesive or a different brand except for Admira Flow restorative at the gingival margins. The gingival margins had significantly more microleakage than the occlusal margins (p < 0.05) except in the Admira Flow group, where microleakage at the occlusal and gingival margins was almost equal.     

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.     

Effect of two light-emitting diode (LED) and one halogen curing light on the microleakage of Class V flowable composite restorations

AIM: The disadvantages of light cured composite resin materials with respect to microleakage are predominantly a result of polymerization shrinkage upon curing. It has been shown curing methods play a significant role in polymerization shrinkage of light-cured composite resins. The purpose of this study was to investigate the effect of light-emitting diode (LED) light curing units (LCUs) compared with a halogen LCU on microleakage of three different flowable composites using self-etch adhesives. METHODS AND MATERIALS: A total of 63 extracted human premolars were prepared with standardized Class V cavity preparations on the buccal and lingual surfaces of each tooth. The occlusal margin of the cavities was located on the enamel and the gingival margin was on dentin. Teeth were randomly assigned to three groups of 21 teeth each as follows: Group 1: Adper Prompt L-Pop + Filtek Flow (3M ESPE); Group 2: AdheSE + Tetric Flow (Ivoclar, Vivadent); and Group 3: Clearfil Protect Bond + Clearfil Protect Liner F (Kuraray Medical Inc.). All the groups were subdivided into three groups according to the curing lights used (n=7). Two LED LCUs, Elipar FreeLight and Elipar FreeLight 2 (3M ESPE), and one halogen-based LCU, Hilux Expert (Benlioglu ), were used. All teeth were then immersed in 0.5% basic fuchsin dye solution for 24 hours after thermocycling (500 cycles; between 5 degrees C to 55 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope (40X magnification) by two examiners. The degree of dye penetration was recorded separately for enamel and dentin. Data were analyzed with the Kruskal-Wallis and Mann-Whitney tests with the Bonferroni correction. RESULTS: No statistically significant differences in microleakage were observed between groups either on enamel or dentin (p>0.05). CONCLUSION: With the limitation of this in vitro study, the differences in microleakage between LCUs used were not statistically significantly different. Elipar Free Light 2 reduces curing time which can be considered as an advantage.     

In vitro evaluation of microleakage of a flowable composite in Class V restorations

The aim of this study was to evaluate microleakage around class V restorations using a flowable composite compared to a hybrid composite. Forty class V cavities were prepared on buccal and lingual surfaces of 20 human teeth, with occlusal and cervical margins at the enamel and cementum/dentin levels, respectively. Specimens were divided into 2 groups with 10 samples each. Group 1: buccal cavities received Paama 2 (conventional bonding agent) + Wave (flowable composite); lingual cavities were restored with Paama 2 + Glacier (hybrid composite). Group 2: buccal cavities received Optibond Solo (self-priming bonding agent) + Wave; lingual cavities were restored with Optibond Solo + Glacier. After being stored in distilled water and finished, the teeth were thermocycled, immersed in a 50% silver nitrate solution and embedded in resin. They were sectioned and the depth of tracer penetration was scored. The results were analyzed using Kruskal-Wallis and Wilcoxon tests. The restorations with flowable composite and those with hybrid composite from the same group showed similar results of microleakage for both occlusal and cervical margins. Optibond Solo improved the sealing of the restorations when compared with Paama 2 (p < 0.01). None of the restorative materials completely sealed the tooth/restoration interface at the cervical margins.     

The effect of flowable resin composite on microleakage and internal voids in class II composite restorations

This in vitro study evaluated the influence of two flowable resin composites on marginal microleakage and internal voids in Class II composite restorations with the margins below the cementoenamel junction (CEJ). Class II cavities randomly divided into four groups: Group I-Filtek with Filtek Flow lining; Group II-Filtek; Group III-Tetric Ceram with Tetric Flow lining; Group IV-Tetric Ceram. After thermocycling tests (5-60 x 1500) and dye soaking, the teeth were sectioned in a mesiodistal direction along their longitudinal axis. Gingival-marginal microleakage and internal voids in three separate portions of the restoration (interface, cervical and occlusal voids) were observed with a microscope. Statistical analyses indicated that the use of flowable resin composites (Groups I and III) provided a reduction in marginal microleakage and a reduction in some parts of the internal voids or total voids (p<0.05). The condensable material (Filtek) in combination with the flowable liner showed fewer voids (interface, occlusal, total) than the hybrid resin (Tetric) (p<0.05). There was a correlation between the number of internal voids or total voids and the marginal microleakage (p<0.05). It was concluded that a composite lining in a Class II resin composite with margins below the cementoenamel junction may reduce marginal microleakage and voids in the interface and the total number of voids in the restoration.     

The effect of flowable resin composites as gingival increments on the microleakage of posterior resin composites

Microleakage has been a major concern in restorative dentistry. The curing contraction of composites still presents a problem with controlling microleakage and postoperative sensitivity. This study investigated the effect of flowable materials on gingival microleakage of microhybrid and packable resin composite restorations. Ninety Class II cavities with cervical margins 1 mm below the CEJ were prepared in 45 extracted human premolars. The teeth were randomly divided into three groups (n=15). In each group, one side of each tooth was restored incrementally with respective composites-SureFil, Filtek P60 and Tetric Ceram; whereas, on the other side, flowable materials-Dyract Flow, Filtek Flow or Tetric Flow-were placed respectively as a 1-mm thick gingival increment before the resin composite restoration. The restored teeth were stored for one week in distilled water at 37 degrees C, thermocycled between 5 degrees C and 55 degrees C and immersed in 0.5% basic fuchsin for 24 hours. Dye penetration was evaluated using a stereomicroscope at 10x magnification. The data were analyzed statistically by Kruskal-Wallis analysis of variance and Mann-Whitney U-tests. The effect of flowable increments on reducing the gingival microleakage was found to be statistically significant for all restorative materials tested (p<0.05).     

Leakage pathway of Class V cavities restored with different flowable resin composite restorations

This study investigated the leakage pathway of facial and lingual Class V cavities restored with different flowable resin composites bonded with one bonding agent by examining the resin/dentin interface. Forty Class V cavities were etched with 37% phosphoric acid gel; Single Bond dental adhesive was applied, then the cavities were randomly divided into four groups (n=10). Three groups were restored with one of three flowable resin composites (Grandio Flow, Filtek Flow and Admira Flow). The fourth group was restored with Z250 (hybrid resin composite) to serve as a control. The specimens were then placed in 50% w/v silver nitrate solution for 24 hours and immersed in a photodeveloping solution for eight hours. Thereafter, the specimens were sectioned bucco-lingually, polished, mounted on stubs, gold sputter coated and examined by scanning electron microscope. Silver particle penetration length with and without gap formation was measured directly on the scanning electron microscope monitor and calculated as a percentage of the total length of the cut dentin surface that was penetrated by silver nitrate. The data were analyzed with one-way ANOVA and Tukey HSD test. The groups restored with Filtek Flow and Admira Flow showed a microleakage pattern where silver nitrate penetration was observed with gap formation at the tooth/restoration interface and Filtek Flow recorded significantly higher leakage than Admira Flow. Grandio Flow showed similar marginal adaptation to Z250 resin composite with no gap formation at the interface. However, silver ions had penetrated beneath the resin-impregnated layer in cavities restored with Grandio Flow and Z250, indicating nanoleakage occurred. This study suggests that volumetric shrinkage in resin composites remains a problem. Although some new technologies are trying to solve the problem of composite shrinkage, the bonding system used in this study did not achieve perfect sealing at the restoration/dentin interface. This might affect durability of the bond to dentin.     

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.     

Effect of Aging on Coronal Microleakage in Access Cavities through Metal Ceramic Crowns Restored with Resin Composites

Purpose: The purpose of this in vitro study was to determine if packable resin composite with/without flowable resin composite has the ability to prevent coronal leakage in restored endodontic access openings following aging. Materials and Methods: Eighty simulated standardized access cavities of metal‐ceramic crowns were fabricated and fixed on Vitrebond cavities filled with an epoxy resin. The specimens were randomly divided into two main groups: (1) Group A—Access cavities filled with only packable composite (Filtek P60); (2) Group B—Access cavities filled with Filtek P60 and a flowable composite (Filtek Z350) as liner. Each main group was further subdivided randomly into four subgroups according to water storage and thermocycling periods. All specimens were immersed in blue ink solution for 24 hours and then sectioned into quadrants. The extension of blue ink along the metal‐ceramic crown/composite resin interface was measured linearly using image analyzer and then analyzed by three‐way ANOVA and independent t‐test with a Mann‐Whitney test. The level of significance was set at p < 0.05. Results: All tested subgroups demonstrated different levels of microleakage. There was no significant difference related to restorative technique; however, there was a significant difference related to water storage and thermocycling. Conclusions: All tested techniques and materials in this study showed microleakage. Packable composite while a flowable liner showed a marginally better result than packable composite alone. Excessive thermocycling resulted in significant differences among the test groups.     

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.     

Dentine bond strength and microleakage of flowable composite,compomer and glass ionomer cement

Background: To assess in vitro the dentine bond strength and microleakage of three Class V restorations viz. flowable composite, compomer and glass ionomer cement. Methods: Eighteen dentine specimens were prepared and randomly distributed among three groups. Three kinds of restoration materials were each bonded on prepared dentine surfaces in three groups as per the manufacturers’ instructions. Group Aelite: Tyrian SPE (a no‐rinse, self‐priming etchant) + One Step Plus (an universal dental adhesive) + Aeliteflo (a flowable composite); Group Dyract: Prime & Bond NT (a no‐rinse, self‐priming dental adhesive) + Dyract AP (a compomer); Group GlasIonomer: GlasIonomer Type II (a self‐cured restorative glass ionomer). Fifteen dentine/restoration microtensile bond test specimens were prepared from each group and were subjected to microtensile bond strength testing. The bond interfaces were observed morphologically using a scanning electron microscope (SEM). Twenty‐four cervical cavities of 4.0 mm mesiodistal length, 2.0 mm occlusogingival height and 1.5 mm depth were prepared at the cemento‐enamel junction (CEJ) on both buccal and lingual surfaces of each tooth. The cavities were each filled with flowable composite (Group Aelite), compomer (Group Dyract) and glass ionomer cement (Group GlasIonomer) using the same material and methods as for the microtensile bond tests. Microleakage of each restoration was evaluated by the ratio of the length of methylene blue penetration along the tooth‐restoration interface and the total length of the dentine cavity wall on the cut surface. Results: One‐way ANOVA and least significant difference (LSD) tests revealed statistically significant differences among the dentine bond strength for Group Aelite (28.4 MPa), Group Dyract (15.1 MPa) and Group GlasIonomer (2.5 MPa). SEM images showed intimate adaptation in the restoration/dentine interfaces of Group Aelite and Group Dyract. All of the systems tested in this study presented microleakage. However, both Group Aelite (0.808) and Group Dyract (0.863) had significantly less microleakage than Group GlasIonomer (0.964). There were no statistically significant microleakage differences between Group Aelite and Group Dyract, and no statistically significant microleakage differences between the occlusal margin and gingival margin. Conclusions: None of the systems tested in this study completely eliminated microleakage. However, both the flowable composite and compomer provided stronger dentine bond strengths and better margin sealing than the conventional glass ionomer cement. Occlusal forces exerted the same effects on microleakage of the occlusal margin and gingival margin in cervical cavities.     

流动树脂衬垫对树脂充填Ⅱ类洞龈壁微渗漏的影响

目的：了解流动树脂衬垫对树脂充填Ⅱ类洞龈壁微渗漏的影响。方法：选择30颗离体前磨牙随机分成A、B、C组,每组10颗,在近远中面制备长方形Ⅱ类洞,分别用通用型树脂直接充填（A组）,龈壁全层流动树脂衬垫后通用型树脂充填（B组）,流动树脂部分衬垫轴壁、龈壁后通用型树脂充填（C组）。所有试件经过温度循环、染色、近远中向连续切片,在30倍体视显微镜下观察龈壁染料渗漏情况。结果：C组的微渗漏明显小于A组和B组（P〈0．05）,A组和B之间差异无统计学意义（P〉0．05）。结论：实验研究表明,使用流动树脂作为衬垫层能明显降低Ⅱ类洞龈壁的微渗漏。     

Effect of flexural load cycling on microleakage of extended root caries restorations

This study evaluated the microleakage of resin-modified glass ionomer, flowable compomer and flowable resin composite restorations on a Class V cavity of simulated advanced root caries under a flexural load cycling condition. Thirty-six non-carious human maxillary premolars were mounted in cylindrical acrylic resin molds. The cavities were prepared in the proximal root surface, from the middle of the buccal surface to the middle of the lingual surface, approximately 1 mm below the cemento-enamel junction, 2 mm axial width and 1.2 mm in depth. The teeth were randomly assigned to one of three groups with 12 teeth in each group: Group 1: Cavity conditioner and Fuji II LC (GC America), Group 2: Prime & Bond NT and Dyract Flow (Caulk-Dentsply), Group 3: Excite and Tetric flow (Ivoclar/Vivadent). Specimens were settled laterally on a fatigue-testing machine that was adjusted to deliver a force of 60N. The specimens were load cycled at 1 Hz for 5000 cycles, placed in a staining solution and sectioned to evaluate microleakage penetration. Results indicate that the coronal and gingival margins showed significant microleakage differences among the three restorations (p<0.05). At the coronal margin, there was no significant difference between Groups 2 and 3. At the gingival margin, there was no significant difference between Groups 1 and 2. It was concluded that the marginal sealing ability of a flowable resin composite under a flexural cycling load was better than in other selected materials and that flowable resin composite with dentin adhesive was a desirable alternative for root caries restorations extended to the proximal surface.     

The elastic moduli across various types of resin/dentin interfaces.

OBJECTIVE: The purpose of this study was to evaluate the elastic moduli of an unfilled adhesive resin (Adper Single Bond) and a filled adhesive resin (Adper Single Bond 2) used with and without a low-viscosity resin (LVR) (Filtek Flow) as an elastic cavity wall in class V composite restorations, restored with a hybrid resin composite (Z250). METHODS: Buccal class V cavities were prepared on extracted premolars and lined with (1) the unfilled adhesive resin, (2) the filled adhesive resin, (3) the unfilled adhesive resin and the flowable composite, and (4) the filled adhesive resin and the flowable composite. All cavities were restored with the hybrid resin composite. The specimens were cut bucco-lingually, embedded in epoxy resin and polished. The polished specimens were evaluated for the elastic modulus with nano-indentation test at the layer of dentin, hybrid layer, adhesive resin, low-viscosity resin and resin composite. RESULTS: The elastic moduli were 25,111 MPa for dentin, 12,243 MPa for hybrid layer of Adper Single Bond, 11,765 MPa for hybrid layer of Adper Single Bond 2, 7595 MPa for Adper Single Bond, 8430 MPa for Adper Single Bond 2, 13,543 MPa for Filtek Flow and 24,494 MPa for Filtek Z250 resin composite. The statistical analysis demonstrated that the elastic moduli were significantly different among layers (p<0.05) except between hybrid layers of unfilled and filled adhesives (p=1.0). CONCLUSION: The application of filled adhesive did not increase the elastic modulus of hybrid layer when compared with the unfilled adhesive resin. The modulus of filled adhesive resin was significantly higher than that of unfilled adhesive resin.     

Microleakage in Class II composite restorations with margins below the CEJ: In vitro evaluation of different restorative techniques

Objectives: The purpose of this in vitro study was to evaluate the microleakage in “deep” Class II composite restorations with gingival cavosurface margin below the CEJ (cemento-enamel junction) and restored with different techniques. Study Design: Fifty human teeth were used. In each tooth two standardized Class II slot cavities (on mesial and on distal surfaces) were prepared: the buccolingual extension of the cavities was 4 mm; the gingival wall was located in dentin/cementum (2 mm beyond the CEJ). The prepared teeth were randomly assigned to 5 experimental groups (of 10 specimens and 20 cavities each) and restored. Group 1: Filtek TM Supreme XTE Flowable (3MESPE) + Universal Filtek Supreme XTE (3MESPE), Group 2: GrandioSO Heavy Flow (Voco) + GrandioSo (Voco), Group 3: SDR™ (Dentsply Caulk) + Esthet-X® HD (Dentsply Caulk), Group 4: SonicFill (Kerr), Group 5: Grandio (Voco). After thermocycling, the specimens were immersed in a 0.5% basic fuchsine dye solution and incubated at 37°C for 24 hours. The teeth were subsequently sectioned mesiodistally. All specimens were examined at 25× in a stereomicroscope and standardized digital images were obtained. Dye penetration was measured from gingival margins. Results: The results demonstrated no significant leakage differences between Group 4 and Group 5, that both showed significantly higher frequency distribution of Score 0. Group 2 and Group 3 showed a significant prevalence of Score 1, whereas Group 1 showed significantly higher frequency of Score 2. Conclusions: None of the restorative techniques tested completely eliminated microleakage dye penetration in dentin margins; marginal adaptation in Class II composite restorations with gingival wall below the CEJ varied in both substrates and from different restorative techniques used. Key words:Microleakage, Class II composite restorations, CEJ.     

Microleakage of composite restorations after acid or Er-YAG laser cavity treatments.

OBJECTIVES: The purpose of this study was to compare microleakage of Class V restorations following acid, laser or laser and acid treatment of cavity walls. METHODS: Standardized lingual and buccal Class V preparations were made in 18 human extracted third molars. The preparations were randomly assigned to three equal groups (n=12). Group 1: cavities were treated with 35% phosphoric acid. Group 2: cavities were irradiated with an Er-YAG laser at 2Hz and 250mJ on dentin and 300mJ on enamel, with water cooling. Group 3: cavities were irradiated with the laser before acid etching. Scotchbond 1 Adhesive System and Z100 resin composite were used for restorations. The specimens were stored in water for 24h at 37 degrees C and thermally cycled (500x) between 6-60 degrees C. After 24h immersion in 0.5% basic fuchsin, dye penetration was recorded according to an ordinal scale. Data were analysed using non-parametric statistical tests (Kruskal-Wallis and Mann-Whitney). RESULTS: On the occlusal walls, microleakage in acid etched cavities was significantly lower than that achieved after laser treatment (P<0.001) or after both treatments (P<0.05). On the gingival walls, no statistical differences were found. SIGNIFICANCE: Laser irradiation of enamel is not a valid alternative to acid-etching pretreatment for resin composite materials adhesion. Acid etching alone gave the lowest microleakage at the occlusal margin. No differences were found for microleakage on gingival wall, although lased dentin surfaces presented several characteristics that appear to be advantageous for bonding.     

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.     

3种复合树脂充填Ⅴ类洞的微渗漏比较研究

目的:比较义获嘉N Ceram纳米瓷化树脂、N Flow流动树脂及Bulk Fill 三次方大块充填树脂充填上颌前磨牙Ⅴ类洞后树脂充填体边缘的微渗漏情况,评估3种不同复合树脂的抗微渗漏性能,寻找较好的充填V类洞的复合树脂材料.方法:选取牙体完整、健康的人离体前磨牙66颗,随机分为3组(n=22).所有样本牙在颊侧颈部制备标准V类箱状洞型(长4 mm、宽3 mm、深2 mm).3组试验牙经选择性釉质酸蚀自黏结后,分别使用N Ceram纳米瓷化树脂(A组)、N Flow流动树脂(B组)及Bulk Fill三次方大块充填树脂(C组)进行充填.充填完成后,3组试验牙均行弱光启动固化,打磨抛光.将3组样本进行1500个周期的冷热循环,2％亚甲基蓝浸泡染色7d,然后沿牙体颊舌向切片.每组随机选取2颗样本牙,在扫描电镜下观察牙体-充填体交界面的密合程度;其余60颗样本牙在体视显微镜下(×40)观察剖面充填体的微渗漏情况.采用Spot Advanced软件测量微渗漏深度,并根据0～3分分别给(牙合)、龈壁微渗漏程度评分.采用SPSS17.0软件包对各组的微渗漏深度分别进行Kruskal-Wallis秩和检验和Mann-Whitney检验.结果:义获嘉Bulk Fill组树脂在3组中龈壁的微渗漏最小,且与另外2组相比有显著差异,N Ceran纳米树脂组与N Flow流动树脂组龈壁的微渗漏均较高(P＜0.05);3组复合树脂材料(牙合)壁的微渗漏无显著差异(P＞0.05);3组树脂(牙合)壁的微渗漏值均比龈壁小且差异显著(P＜0.05).结论:3组树脂在(牙合)壁的微渗漏值无显著差异.义获嘉Bulk Fill组树脂充填V类洞时.在3组中龈壁的微渗漏最小,且与另外2种树脂之间有显著差异.