Microleakage in class V gingiva-shaded composite resin restorations

The purpose of this study was to evaluate the microleakage in Class V cavities restored with a new gingiva-shaded microhybrid composite resin and with a conventional microhybrid composite resin using three different dentin bonding systems (DBS). Class V cavities were prepared in sixty freshly extracted human teeth with the incisal margin in enamel and the apical margin in dentin/cementum. Restored specimens, after thermocycling, were placed in 2% methylene blue solution for 24 hours. Longitudinal sections were obtained and studied with a stereomicroscope for assessment of the microleakage according to degree of dye penetration (scale 0-3). Data were analyzed with Kruskal-Wallis test and with Mann-Whitney U-test.IN THIS STUDY THERE WAS NO LEAKAGE IN ENAMEL: all the cavities showed no dye penetration at the incisal margins (located in enamel). None of the DBS used eliminated microleakage in apical margins (located in dentin or cementum): three-step total-etch and single-step self-etch were more effective in reducing microleakage in dentin margins when compared with two-step total-etch. This in vitro study concluded that microleakage in Class V cavities restored with the composite resins tested is similar.     

Microleakage of Class V restorations using two different compomer systems: an in vitro study

This study compared the marginal microleakage of Class V cavities restored with Dyract-AP and F2000. Forty Class V cavity preparations were performed on extracted human teeth. As a negative control, twenty teeth were used without Class V preparations. The apical foramina of the teeth were sealed with a layer of varnish and amalgam restorations. Class V cavity preparations with occlusal margins in enamel, and gingival margins in cementum or dentin that measured approximately three millimeters in width (gingival-occlusal) and length (mesial-distal), were prepared on the buccal surface of the teeth. Samples were divided randomly into 2 groups of 15, and restored per manufacturer's instructions using experimental primer/conditioner (PCC, D/C) and Single Bond Adhesive (3M). All restorations were polished with an abrasive finishing kit. After storage in 37 degrees C water for 24 hours, all specimens were thermocycled between 5 degrees C and 55 degrees C for 500 cycles with a 30-second dwell time, followed by immersion in 0.2% basic fucsine for 24 hours. Teeth were then embedded in cold cure acrylic resin, sectioned longitudinally, and the dye penetration at the enamel and cementum margins were scored at 30x magnification. Evaluations were rated from 0 to 3 (0 = no leakage; 1 = dye penetration up to one-half of the preparation depth; 2 = dye penetration more than one-half preparation depth, but less than the axial wall; 3 = dye penetration along the axial wall). Both F-2000 and Dyract-AP indicated no leakage in the enamel margins. Dyract-AP showed no leakage at either the enamel or dentin margins. Fisher's Exact Test revealed that this difference in dentin margins was statistically significant (p < 0.05). Under the given conditions, Dyract-AP and F-2000 demonstrated resistance to microleakage in enamel, and showed Dyract-AP to be more resistant to microleakage in dentin than F-2000.     

Sealing effectiveness of etch-and-rinse vs self-etching adhesives after water aging: influence of acid etching and NaOCl dentin pretreatment

PURPOSE: To determine the marginal leakage of Class V restorations bonded with etch-and-rinse and self-etching adhesives applied after different dentin pretreatments over a maximum storage time of 24 months. MATERIALS AND METHODS: Standardized mixed Class V cavities (5 mm x 3 mm and 2 mm deep) were cut on the buccal and lingual surfaces of 180 human molars. Two self-etching adhesive systems, Adper Prompt L-Pop (3M ESPE) and Clearfil SE Bond (Kuraray), and one etch-and-rinse bonding agent (One Step, Bisco) were applied as follows: 1. according to manufacturers' instructions; 2. after 37% H3PO4 etching for 15 s; 3. after 37% H3PO4 etching for 15 s and 5% NaOCl aq application for 2 min. Teeth were stored for 24 h, 6, 12, and 24 months in saline solution at 37 degrees C before being stained in 0.5% solution of basic fuchsine. Dye penetration was scored on a 0 to 3 ordinal scale and analyzed with the Kruskal-Wallis H test (p < 0.05), Mann-Whitney U-test (p < 0.01), and Wilcoxon paired test (p < 0.05). RESULTS: Significant differences exist after using the tested adhesives at dentin and enamel margins. Adhesive type and substrate pretreatment had a significant effect on the long-term sealing of Class V restorations, and aging increased leakage overtime. The extent of leakage at the enamel margins was lower than that at dentin margins. One Step recorded the best results after 24 months. CONCLUSION: Optimal adhesion of restorative materials to enamel and dentin is hampered by a reduction in marginal seal over time. Alternative dentinal treatments (etching or collagen removal) might increase bonding efficacy, depending on the adhesive system 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.     

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.     

Assessing microleakage in resin composite restorations rebonded with a surface sealant and three low-viscosity resin systems.

OBJECTIVES: The aim of this study was to assess the ability of three low-viscosity resin systems (Unibond, Single Bond, and Fluorseal), used as rebonding agents, and a specific surface-penetrating sealant (Fortify) to prevent microleakage in Class V resin composite restorations. METHOD AND MATERIALS: Fifty Class V cavities with the occlusal margin in enamel and the cervical margin in dentin and cementum were prepared on both the buccal and lingual surfaces of sound extracted premolars and restored with a hybrid light-cured resin composite. After finishing and polishing, restorations were randomly assigned to one of five equal groups (n = 10): a control, without surface sealing, and four experimental groups in which margins were etched and rebonded. Specimens were thermocycled, immersed in a 50% silver nitrate solution, sectioned longitudinally, and analyzed for leakage at the occlusal and cervical interfaces. RESULTS: Statistical analysis showed significantly less leakage at the enamel margins for all groups. Fortify and Unibond were statistically similar and provided better marginal sealing at dentin and cementum interfaces. Fluorseal showed the poorest ability to prevent microleakage. CONCLUSION: The rebonding technique may substantially minimize microleakage at dentin and cementum margins of composite restorations, when a resin system with sufficiently low viscosity is used as a surface sealant, regardless of whether it has been specified for such a purpose.     

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.     

Effect of various surface treatments on the microleakage and ultrastructure of resin-tooth interface

This study evaluated the effect of collagen removal and sodium ascorbate treatment of acid-etched dentin on the microleakage and ultrastructure of resin-tooth interface under moist and dry conditions using an acetone-based 1 bottle adhesive system. Class V cavities were made on the buccal surfaces of 90 premolars scheduled for orthodontic extraction. The cavities were etched with 37% phosphoric acid (DPI tooth conditioning gel/India) for 15 seconds. The teeth were divided into six groups with 15 teeth each. In Group 1, the etched surface was blot dried with a dry cotton pellet, leaving it visibly moist, and Prime & Bond NT (Dentsply Detrey/ Germany) was applied. In Group 2, after acid conditioning, the cavity surface was air dried for five seconds, followed by application of Prime & Bond NT. In Group 3, 3% NaOCl (Hyposol, Prevest Denpro Ltd/India) was applied to the acid-conditioned cavity surface for two minutes. The surface was blot dried before bonding. In Group 4, after NaOCl treatment, the surface was air dried for five seconds, followed by application of the bonding agent. In Group 5, 10% sodium ascorbate (chemically pure) was applied to the NaOCl-treated acid conditioned tooth surface for one minute. The surface was blot dried before bonding. In Group 6, after sodium ascorbate treatment as in Group 5, the cavity surface was air dried for five seconds before bonding. The cavities were restored with the hybrid composite Spectrum TPH (Dentsply Detrey, Konstanz, Germany). The teeth were extracted immediately after restoration, and the specimens were prepared for microleakage testing using 2% methylene blue dye and for scanning electron microscopic evaluation. The results of the dye penetration were analyzed with Kruskal-Wallis non-parametric analysis followed by the Mann-Whitney U test at a significance level of p = 0.05. After acid etching, the conventional acid etched groups and groups with NaOCl treatment demonstrated extensive leakage. Sodium ascorbate treatment of the NaOCl-treated dentin significantly reduced microleakage. No statistically significant difference between moist and dry bonding was observed in all groups. Although resin tag penetration improved in both the NaOCl-treated and NaOCl/ascorbate-treated groups, an absence of gap at the resin dentin interface was observed only for the NaOCl/ascorbate-treated groups.     

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.     

Comparison of microleakage for three one-bottle and three multiple-step dentin bonding agents.

PURPOSE: This in vitro study compared the ability of several recently introduced 1-bottle adhesives to their preceding multiple-step dentin bonding agents in reducing microleakage around Class V composite restorations. MATERIAL AND METHODS: Facial and lingual Class V cavities were prepared in 48 molar teeth, which were randomly divided into 6 equal groups. Three groups used the fourth-generation multiple-step systems, and 3 used the fifth-generation single-bottle adhesives. All cavities were restored by composite and subjected to thermocycling and intermittent occlusal loading. After immersion in 0.5% basic fuchsin, the teeth were cut faciolingually in 5 consecutive sections and evaluated for dye penetration using a binocular stereomicroscope. RESULTS: There was no statistically significant difference in the degree of microleakage comparing the adhesive's generation and manufacturer and the location of the cavity margins. A significant interaction was found between margin location and manufacturer, which implied that the sealing capacity at the enamel and cementum margins was material-specific. CONCLUSION: Scotchbond Multi-Purpose and Single Bond adhesives provided the best seal for enamel margins, and One-Step and Optibond FL adhesives were best for cementum margins.     

Comparison of microleakage of three acid-base luting cements versus one resin-bonded cement for Class V direct composite inlays

STATEMENT OF PROBLEM: Demineralized dentin beneath set cement may adversely affect microleakage under fixed restorations. PURPOSE: Microleakage of direct composite inlays cemented with acid-base cements and a methyl methacrylate resin cement were evaluated to determine their effect on the integrity of the underlying hybridized dentin. MATERIALS AND METHODS: Sixty Class V box preparations (3 mm x 3 mm x 1.5 mm) were precisely prepared in previously frozen bovine teeth with one margin in enamel and another margin in dentin. Direct composite inlays (EPIC-TMPT) for each preparation were divided into 4 groups of 15 specimens each and cemented with 3 acid-base cements (control group): Elite, Ketac-Cem, Hy-Bond Carbo-Cem, and 1 adhesive resin cement: C&B Metabond. All specimens were stored in distilled water for 24 hours at 37 degrees C before immersion in 0.5% basic fuchsin for 24 hours. The dye penetration was measured on the sectioned specimens at the tooth-cement interface of enamel and cementum margins and recorded with graded criteria under light microscopy (Olympus Vanox-T) at original magnification x 50, 100, and 200. A Kruskal-Wallis and the Mann-Whitney test at P<.05 were used to analyze leakage score. RESULTS: All cementum margins of the 3 acid-base cements tested demonstrated significantly higher leakage scores than cementum margins for inlays cemented with the resin cement tested(P<.01). No leakage along the tooth-cement interface was found for inlays retained with the adhesive resin cement. CONCLUSIONS: Within the limitations of this study, the 3 acid-base cements tested exhibited greater microleakage at the cementum margins than did the adhesive resin cement that was tested.     

Microleakage in MOD resin composite with three dentin bonding agents

The extent of microleakage under MOD composites was studied when an aluminum oxalate dentin bonding agent (Tenure), a phosphonated resin bonding agent (Bondlite), and a glass-ionomer cement (Ketac Silver) were used. Three groups of 10 extracted molars were prepared with MOD cavities; one box ended on enamel, the other on cementum. In Group 1, Bondlite was applied to dentin and etched enamel before the sample was restored with a light-cured hybrid composite. In Group 2, a 2-mm increment of Ketac Silver was placed in each box before Bondlite and composite. In Group 3, Tenure was applied to dentin before being restored. Teeth were thermal-cycled, stained in silver nitrate, sectioned, and scored for microleakage. Microleakage along the gingival floor was significantly less at enamel margins than at cementum margins in all three groups. All groups showed severe marginal microleakage on cementum.     

Microleakage of composite restorations bonded with three new dentin bonding agents.

This report evaluates the impact of two dentin bonding techniques on microleakage of Class V restorations bonded with three new dentin bonding systems. Forty-eight extracted human premolar and molar teeth were randomly assigned to four groups for bonding with EBS Bonding System (ESPE, Seefeld, Germany); Syntac Single-Component (Ivoclar-Vivadent, Schaan, Liechtenstein); Scotchbond 1 (3M Dental Products, St. Paul, Minnesota); and a control, Prime and Bond 2.1 (Dentsply, DeTrey, Konstanz, Germany). Cavities were cut in both the buccal and lingual surfaces. The coronal half of each preparation was in enamel, and the gingival half was in cementum or dentin. The cavities were restored with composite after the application of dentin bonding agents, using two different drying techniques for each material. The teeth were stored in distilled water for 6 days at 37 degrees C and then thermocycled. The restorations were examined microscopically for leakage, using Procion brilliant red as a marker. All groups showed microleakage at both the enamel and dentin margins. At the gingival margin, there was no significant difference between any of the experimental materials and the control for either wet bonding (Kruskal-Wallis: p = .8920) or dry bonding (Kruskal-Wallis: p .9973); or between the two techniques for each material (Mann-Whitney U in all cases p > .05). Scanning electron microscopic examination confirmed that the zones of microleakage, as indicated by dye penetration, were principally resincohesive failures within the collagen-rich hybrid layer. Three water-based bonding agents were unable to prevent microleakage at either the enamel or dentin margins of Class V cavities regardless of which bonding technique was employed. All systems behaved equally.     

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 and marginal hybrid layer formation of compomer restorations

The tested hypotheses of this study were that dentin enamel bonding agents (DBAs) proposed for compomers create a hybrid layer (HL) that seals the margins of Class V restorations and HL is free from voids or gaps on both enamel and dentin margins. For purposes of this study, Class V restorations (n = 70) were made in vitro at the CEJ in extracted third molars. Different systems (bonding agent + compomer) were selected. After finishing with discs, each margin was polished with diamond polishing paste for one minute, treated with a 2.5% NaOCl gel for 10 seconds and washed with deionized water to remove polishing debris and non-infiltrated collagen. All restorations were immersed in dye solution for 24 hours, then inspected along the margins. SEM analysis was used to evaluate the morphology of the marginal HL and microleakage tests to evaluate their ability to seal the margins of restorations. Marginal leakage was observed along the dentin and enamel margin. A thin marginal HL (0.5-1.2 microm) was detected only along the dentin margin of several bonding systems but not along the enamel margin. Porosities and gaps were detected along margins when no HL was observed. The results demonstrated that the tested bonding agents for compomers produced a thin marginal hybrid layer, especially along the dentin margin. Microleakage had a relationship with the morphology (gap, porosities and thickness) of this hybrid smear layer. In conclusion, the DBAs tested specifically developed for compomers did not ensure an intimate interfacial adaptation, because microleakage was detected along the enamel and dentin interfaces and the marginal hybrid layer was only partially homogeneous.     

Adhesion of Indirect MOD Resin Composite Inlays Luted With Self-adhesive and Self-etching Resin Cements

SUMMARY This study investigated the effect of loading on the bond strength to dentin and microleakage of MOD indirect composite restorations bonded with self-adhesive and self-etching resin cements with or without acid etching of the proximal enamel margins. Class II MOD cavities were prepared in 48 molar teeth into dentin and divided into three groups of 16 teeth. Impressions were taken and indirect composite inlays fabricated (Estenia C & B). The enamel margins of the proximal boxes of half the specimens were phosphoric acid etched, and the inlays were cemented with one of three cements (Panavia F 2.0, SA Cement, or Rely X Unicem). After luting, eight teeth in each cement group were mechanically loaded at 2.5 cycles/s for 250,000 cycles. Unloaded teeth acted as controls. Teeth were stored in Rhodamine B solution for 24 hours, sectioned buccolingually at the proximal boxes to examine microleakage using confocal microscopy, and further sectioned for μTBS testing of the resin-dentin interface. Analysis of variance was performed to assess the effect of loading and acid etching on microleakage and bond strength. Acid etching had no effect on microleakage. No significant difference in the dentin bond strengths between the three cements existed after loading. Panavia F 2.0 exhibited a significant reduction in bond strength. With regard to microleakage at the proximal boxes, loading had no effect on dye penetration at the cavity floor. However, at the axial walls, loading had a significant deleterious effect on Panavia F 2.0. No difference in microleakage existed between the three cements at both sites before and after loading. In conclusion, the two tested self-adhesive cements exhibited similar bond strengths before and after loading to the self-etching resin cement. Loading reduced dentin bond strengths and increased microleakage at the resin-dentin interface. However, acid etching of the enamel margins had no significant effect on microleakage in the approximal regions of the bonded inlays.     

Effect of remaining demineralised dentine on dental microleakage accessed by a dye penetration: how to inhibit microleakage?

OBJECTIVES: To demonstrate that microleakage has taken place at the defect, which was analysed previously by a tensile test using dumbbell shaped specimens trimmed from bonded resin/dentine restorations, and to suggest how microleakage can be inhibited reliably in dental treatment. METHODS: A total of 60 Class V box cavities were prepared at the cemento-enamel junction on fresh bovine incisors and randomly divided into four groups of 15 specimens each. Exposure times of etching for 10:3 conditioner were set at 10, 30 or 60 s, and for 10% phosphoric acid (positive control) at 10 s. The cavity walls were rinsed with water for 10 s, air-dried for 10 s and hybridised with 4-META/MMA-TBB resin. All the cavities were filled with a light cured resin composite and stored in 37 degrees C water for 24 h and then immersed in 15% methylene blue for 2 h. The length of dye penetration along the interface was graded by defined criteria and analysed using Kruskal-Wallis and Mann-Whitney tests. The dye penetration patterns were examined by light microscopy and the remaining demineralised dentine was analysed by Transmission Electron Microscopy (TEM). RESULTS: The least leakage score was obtained in 10s-10:3 etched group with 12 out of 15 specimens demonstrating no leakage. Leakage was significantly lower at the cementum margin than for the other three groups. No significant difference in the extent of greatest dye penetration was found between the 60s-10:3 and 10s-phosphoric etched groups. Dye penetration along the cementum margins was significantly higher than that of the enamel margins in all groups, except the 10s-10:3 etched group. TEM examination confirmed that there were exposed collagen fibrils in the remaining demineralised dentine, where microleakage had taken place. SIGNIFICANCE: It could be concluded from this study that microleakage has taken place at the defect in the bonded specimens which has correlations with zones of incompletely infiltrated demineralised dentine that was observed using TEM. A reliable method of inhibiting microleakage is the presence of well prepared hybridised dentine.     

Microleakage of class V resin composite restorations after bur, air-abrasion or Er:YAG laser preparation

This in vitro study compared the microleakage of Class V resin composite restorations placed in cavities prepared with a high-speed dental bur, air-abrasion or Er:YAG laser. Twenty sound extracted human third molars were selected and randomly assigned to four equal Groups (n=10): Group I, cavities were cut by dental drill at high-speed; Group II, aluminum oxide air-abrasion was used for cavity preparation, and in Groups III and IV, cavities were prepared by Er:YAG laser. Following cavity preparation, Groups I and II were acid-etched, Group III was treated only by Er:YAG laser and Group IV was conditioned by Er:YAG laser followed by acid-etching. Cavities were restored (Single Bond + Z-100) and the teeth stored for seven days in distilled water. Then, the restorations were polished and the specimens thermocycled, immersed in a 0.2% Rhodamine solution, sectioned and analyzed for leakage at the occlusal (enamel) and cervical (dentin/cementum) interfaces using an optical microscope connected to a video camera. The images were digitized and software was utilized for microleakage assessment. Upon analyzing the results, statistically significant differences (p<0.01) between the occlusal and cervical regions for all groups was observed, and, as a rule, there was better marginal sealing at the enamel margins. The highest degree of infiltration was observed for cavities prepared and treated exclusively by Er:YAG (Group III). The other experimental groups showed statistical similarities in the amount of marginal leakage at the enamel margins. However, at the cervical margins, there was a significant difference (p<0.05) between Group I and the remaining groups. None of the techniques completely eliminated marginal microleakage at the dentin/ cementum margins.     

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.