Effect of different application and polymerization techniques on the microleakage of proximal resin composite restorations in vitro

This in vitro study investigated cervical microleakage of proximal resin composite restorations placed with three application and polymerization techniques. Uniform mesio-occlusal-distal (MOD) preparations featuring cervical margins above (mesial) and below (distal) the CEJ suitable for restoration with resin composite were copy milled into 33 recently extracted permanent molars. The teeth were divided randomly into three groups of 11 teeth and restored using a conventional incremental technique (Group A) and two novel curing devices (Groups B and C). After 24 hours, a dye penetration test was used to assess microleakage. Conventional placement in preparations with cervical margins in enamel had significantly lower interfacial leakage scores than those recorded for placement in preparations with margins in cementum regardless of the technique used to place the restorative material. Use of the two novel curing devices conferred no advantage in reducing microleakage irrespective of where preparation margins were placed.     

Effect of cyclical lateral forces on microleakage in cervical resin composite restorations.

OBJECTIVE: The aim of this study was to assess the effect on microleakage of cyclic lateral fatigue forces in different types of cervical resin composite restorations. METHOD AND MATERIALS: V-notch cavities were prepared at the cementoenamel junction in 60 extracted human premolars and restored with a bonding system along with one of the following resin composites: hybrid resin composite, microfilled resin composite, and flowable resin composite (20 each). Ten specimens from each group of 20 were subjected to 8,400 cycles of lateral fatigue forces (44 N) at the occlusal half of the clinical crown in a machine specifically developed for this purpose. The other 10 specimens of each group served as controls, representing the microleakage that occurred without lateral fatigue forces. All specimens were stained with a 50% silver nitrate solution and sectioned sagittally. A scoring system of 0 to 6 was used to record the amount of die penetration along the restoration-tooth interface. RESULTS: There was leakage in both the fatigued specimens and the nonfatigued control specimens. There were significant differences in the mean values of microleakage for the restorative materials studied. In the nonfatigued groups, hybrid resin specimens exhibited significantly more microleakage at the dentin-resin interface than did microfilled or flowable resin specimens. In the fatigued groups, hybrid resin specimens exhibited significantly more leakage at the dentin-resin interface than did microfilled resin specimens. CONCLUSION: The least elastic resin composite tested, the hybrid material, generally showed the most leakage. This suggests that the elasticity of these resin composite restorative materials may be a factor in the amount of microleakage in cervical restorations.     

Effects of flowable resin on bond strength and gap formation in Class I restorations.

OBJECTIVES: This study measured resin/dentin bond strengths and evaluated gap formation at the pulpal floor of occlusal composite restorations using a flowable resin as a liner with either bulk or incremental placement of the restorative composite. METHODS: Class I occlusal preparations were made in 16 extracted molars, and were randomly divided into two groups for restoration using either One-Step adhesive (OS, BISCO) and Renew composite (RW, BISCO) or OptiBond SOLO adhesive (SOLO, Kerr) and Herculite XRV composite (XRV, Kerr). A flowable resin [AEliteFlo (AE, BISCO) or Revolution (RV, Kerr)] was applied as a liner in half of the specimens of each group. The lined and unlined groups were restored with composite cured in bulk, or cured in 1.5 mm increments. After 24 h in water, the teeth were sectioned into 0.7-mm thick slabs and were examined with an optical microscope (400 x) to determine the presence of internal resin-dentin gaps. The gap-free specimens were trimmed and were subjected to microtensile bond strength testing. Specimens that contained gaps had Knoop hardness of the restorative material measured. RESULTS: All incrementally filled restorations were well adapted to the pulpal floor but nearly all bulk-cured specimens had gaps between the flowable and the hybrid composites. The use of a flowable resin increased the bond strength of OS, but not SOLO. SIGNIFICANCE: The incremental technique prevented gap formation regardless of the use of a flowable resin. In contrast, the use of a flowable composite did not guarantee gap-free restorations or improved bond strength of resin to dentin in bulk-filled restorations.     

Protective effect of resin coating on the microleakage of Class V restorations following treatment with carbamide peroxide in vitro

This in vitro study evaluated the effects of a resin coating on the microleakage of Class V restorations due to bleaching. One-hundred and sixty Class V cavities were randomly restored with one of four different restorative materials (n = 40): a compomer (Dyract AP), a conventional glass-ionomer cement (Ketac Molar Easymix), a resin modified glass-ionomer cement (Fuji II LC) and a resin composite (Filtek Z350). For each kind of material, 40 restorations were divided into four subgroups: bleached with resin coating (group BC), bleached without resin coating (group B), immersed in artificial saliva with resin coating (group SC), immersed in artificial saliva without resin coating (group S). In groups B and BC, the specimens were bleached with 10% carbamide peroxide gel for eight hours daily, while groups SC and S were stored in artificial saliva instead. After 28-day treatment, all the samples were subjected to a dye penetration test using the multiple-sectioning technique. In addition, one more test was performed to investigate the color difference between the coated and uncoated tooth surface after bleaching. There was a statistically significant increase in cervical microleakage in the group B specimens of Fuji II LC and Ketac Molar Easymix compared to their respective control specimen (group S). These effects on microleakage were not found in the bleached specimens with resin coating (group BC). There was also no visually-detectable color difference between the coated and uncoated tooth surface. In conclusion, resin coating is an effective method for avoiding the bleaching-induced microleakage of glass-ionomer cement.     

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.     

Effect of centripetal and incremental methods in Class II composite resin restorations on gingival microleakage

AIM: The aim of this study was to evaluate the microleakage at gingival margins below the cementoenamel junction (CEJ) of Class II composite restorations using various placement techniques. METHODS AND MATERIALS: Sound human maxillary premolars were selected. Eighty slot-style cavities on the mesial or distal surfaces were prepared with the cervical margins located apical to the CEJ. The specimens were divided into two groups based on the restorative technique utilized (centripetal or incremental). Each group was then categorized into two subgroups according to the type of matrix used resulting in a total of four experimental groups as follows: IP=Incremental and Palodent matrix, IT = Incremental and Transparent matrix, CP= Centripetal and Palodent matrix, and CT = Centripetal and Transparent matrix. Following restoration with a total etch adhesive (Single Bond) and a resin composite (Z100), the teeth were thermocycled. Then specimens were immersed in 0.5% basic fuchsin dye for 24 hours at a temperature of 37 degrees C. Sectioned restorations were examined under a stereomicroscope (40X magnification), and the extent of the microleakage was scored and recorded. Data were analyzed using the Kruskal-Wallis non-parametric statistical test (P=0.05). RESULTS: In the four groups of the study no significant differences in the mean rank of microleakage were observed (p>0.05). CONCLUSION: When the gingival margin was located on cementum, the kind of matrix and filling technique did not reduce the microleakage.     

Evaluation of Microleakage in Tenure-Based Restorations

This study evaluates the effects of six composite resins, which use three different curing systems, on the ability of Tenure to resist microleakage. The curing systems were a photoinitiated dual-cure system, a dual-cure system, and light-cure systems. A total of 39 human molars were used. Following 2,000 cycles on a thermocycler, specimens were exposed to 0.2 percent basic fuchsin dye for 24 hours and then examined for microleakage. Results indicated that the composite resin plays an important role in the ability of a restorative system to resist microleakage. The photoinitiated dual-cure system produced significantly less microleakage than light-activated systems. No difference in microleakage was found between light-activated systems and the dual-cure system.     

Evaluation of microleakage in tenure-based restorations

This study evaluates the effects of six composite resins, which use three different curing systems, on the ability of Tenure to resist microleakage. The curing systems were a photoinitiated dual-cure system, a dual-cure system, and light-cure systems. A total of 39 human molars were used. Following 2,000 cycles on a thermocycler, specimens were exposed to 0.2 percent basic fuchsin dye for 24 hours and then examined for microleakage. Results indicated that the composite resin plays an important role in the ability of a restorative system to resist microleakage. The photoinitiated dual-cure system produced significantly less microleakage than light-activated systems. No difference in microleakage was found between light-activated systems and the dual-cure system.     

Effect of bleaching agents on the microhardness of tooth-colored restorative materials

STATEMENT OF PROBLEM: There is no consensus concerning the effect of bleaching gels on microhardness of restorative materials. Information about the effect of whitening strips on microhardness of restorative materials is also limited. PURPOSE: The purpose of this study was to evaluate the effect of a bleaching gel and a whitening strip on the microhardness of 3 tooth-colored restorative materials. MATERIAL AND METHODS: Forty cylindrical specimens (6 x 2 mm) of each restorative material, including a nanohybrid composite resin (Grandio), a polyacid-modified composite resin (Dyract eXtra), and a glass-ionomer cement (Ionofil Molar AC), were prepared and stored in distilled water at 37 degrees C for 24 hours. The specimens were then polished using medium, fine, and superfine polishing disks and stored in 37 degrees C distilled water for 7 days. Specimens were divided into 4 groups (n=10). One group was selected for baseline Vickers hardness measurements (load 100 g, dwell time 20 seconds) of the top surfaces. The other 3 groups were treated for 21 days with 1 of the following: distilled water (control), bleaching gel (10% carbamide peroxide), or whitening strip (14% hydrogen peroxide). The top surfaces of the treated specimens were also subjected to the same hardness testing performed for the baseline specimens. Data were analyzed with 2-way analysis of variance and Tukey Honestly Significant Difference tests (alpha=.05). RESULTS: There were no significant differences in microhardness between the test groups of each restorative material. However, significant differences in microhardness were observed among restorative materials. For all test groups, composite resin showed the highest hardness values, whereas glass-ionomer cement presented the lowest (P<.05). CONCLUSION: The bleaching products used in this study did not adversely affect the microhardness of the restorative materials.     

Polymerization shrinkage of experimental short glass fiber-reinforced composite with semi-inter penetrating polymer network matrix.

OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on polymerization resin shrinkage-strain, shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced polymerization shrinkage stress and microleakage compared to a conventional restorative composite.     

Coronal microleakage of temporary restorations in previously restored teeth with amalgam and composite

AIM: This study evaluated microleakage at the interface between various temporary restorative materials and existing amalgam or composite restorations, and dental tissues in previously restored teeth after partial removal of the restoration. MATERIALS AND METHODS: The distal half of amal gam (Ag) and composite restorations (Co) in 45 teeth were removed, then filled with temporary restorative materials (IRM, Coltosol and CLIP). After thermal cycling, microleakage was measured microscopically as the penetration of basic fuchsine according to a four-unit-scale: The data were evaluated with Friedman and Kruskal-Wallis tests using Bonferroni correction (p < 0.05). RESULTS: In almost all groups except the Co-IRM and Ag-CLIP interface, lower microleakage values were observed in temporary restoration-permanent restoration interfaces compared to temporary restoration-tooth interfaces. For the Ag and Co groups except for the Ag-IRM-b interfaces, the highest microleakage values were observed with IRM for b and c interfaces followed by Coltosol and CLIP. Interestingly, although CLIP was a temporary restoration, CLIP-tooth interface (Ag-CLIP-c) values were lower than amalgam-tooth interface (Ag-CLIP-a) values. CONCLUSIONS: CLIP provided a better seal against microleakage at amalgam and especially composite interfaces. This material also provided a better seal against microleakage at the tooth tissue interface. The use of a resin based temporary restorative material over partially removed resin composite restorations could be beneficial in achieving better resistance to marginal leakage. Within the limitations of this study, maintaining partially removed permanent restorations does not seem to cause a problem with achieving marginal seal.     

Influence of adhesive system and placement technique on microleakage of resin-based composite restorations

PURPOSE: To analyze the influence of two placement techniques and two adhesive systems on the marginal microleakage of Class II resin-based composite restorations using different resin composite materials. MATERIALS AND METHODS: Two hundred standardized Class II cavities (5 mm x 3 mm x 1.5 mm) were cut in human premolars and restored using five resin composite materials (A.L.E.R.T.-AL, Solitaire-SO, SureFil-SU, Filtek A110-A, and Z100-Z), two adhesive systems (Bond 1-B1 and Etch & Prime 3.0-EP), and two placement techniques (incremental or bulk). Specimens were thermocycled (700 cycles, 5 degrees - 55 degrees C, 1 min dwell time), immersed in 0.5% methylene blue solution for 4 h, and sectioned longitudinally to evaluate the extent of microleakage. Data were submitted to statistical analysis using the Kruskal-Wallis test. RESULTS: It was observed that both adhesive systems presented similar results (p > 0.05), and neither achieved complete marginal sealing. The bulk placement technique led to greater microleakage than the incremental technique (p < 0.001). Restorations prepared using SO resin composite showed greater microleakage than those performed using Z or AL materials. However, SO obtained similar values of microleakage when compared to SU and A materials. CONCLUSION: The use of incremental placement technique resulted in less microleakage for Class II resin-based composite restorations. No difference was observed among adhesive systems regarding prevention of marginal dye penetration. Furthermore, the type of resin composite material employed for restoration may have an influence on the extent of microleakage.     

Effect of insertion technique and adhesive system on microleakage of Class V resin composite restorations

PURPOSE: To evaluate the effect of different insertion techniques and adhesive systems on microleakage of Class V composite resin restorations. MATERIALS AND METHODS: Forty-eight human molars were randomly assigned to four groups (n = 12). Standardized mixed Class V cavities (enamel and dentin margins) were prepared at the CEJ. A total-etch (Adper Scotchbond MultiPurpose) and a self-etching (iBond) adhesive system were evaluated using either an incremental or single-step (bulk) insertion technique. The preparations were restored with Esthet*X micromatrix hybrid composite. The teeth were thermocycled 1000 cycles, immersed in 1% methylene blue dye for 24 h, and invested in acrylic resin. The specimen blocks were then sectioned longitudinally, with dye penetration (microleakage) examined with a 20X binocular microscope. Enamel and dentin margins were scored separately for microleakage using an ordinal ranking system. Results were analyzed using non-parametric tests at a p < 0.05 level of significance. RESULTS: Significance was exhibited between the groups (adhesive material/insertion technique) at the coronal and apical margins. At the coronal margin, the total-etch adhesive/incremental insertion group exhibited significantly less leakage than the other groups, while at the apical margin, the total-etch adhesive/incremental insertion group showed significantly less leakage than the self-etching adhesive/bulk insertion group. Significantly less leakage was found at the coronal margins compared to the apical margins of the material/technique groups. CONCLUSION: The use of a total-etch adhesive system and incremental insertion of composite significantly reduced microleakage at the coronal and apical margins of Class V composite restorations.     

In vitro evaluation of microleakage of indirect composite inlays cemented with four luting agents

STATEMENT OF PROBLEM: Microleakage around dental restorations is implicated in the occurrence of secondary carious lesions, adverse pulpal response, and reduced restoration longevity. PURPOSE: The aim of this in vitro study was to evaluate the microleakage of indirect resin composite inlays cemented with 4 luting agents. MATERIAL AND METHODS: Standardized Class V inlay preparations overlapping the cemento-enamel junction were prepared on the buccal and lingual surfaces of 40 extracted human mandibular third molars. Eighty postpolymerized, heat-treated resin composite inlays (Targis, 72 specimens, 8 controls) were processed in stone replicas and cemented into the preparations using 4 luting agents (n = 18 + 2 controls for each cement group): a resin composite used with a bonding agent (Variolink II/Excite), a resin composite used with a self-etching primer, but without bonding agent (Panavia F/ED Primer), a modified resin composite used with a bonding agent (Resinomer/One Step), and a resin-modified glass-ionomer cement (Fuji Plus). Thirty-six inlays (n = 9 + 1 control) were subjected to thermal cycling (2000 cycles, 5 degrees C/55 degrees C), whereas the other 36 were not. All the teeth were then immersed in 1% methylene blue dye solution for 48 hours. Microleakage score, margin location (enamel/cementum), thermal cycling history, and preparation location (buccal/lingual) were analyzed using a multivariate model (alpha = .05). Multivariate analysis was performed using a polychotomous logistic regression. RESULTS: The preparation location had no significant effect on dye penetration. The margin location (enamel or cementum) and the thermal cycling had a significant effect on microleakage (odds ratios [ORs] = 17.6 and 8.04, respectively). In comparing the 3 resin-based luting agents (Variolink II, Panavia F, and Resinomer) to Fuji Plus, Panavia F exhibited the lowest significant overall microleakage (OR = 0.09), followed by Variolink II (significant OR equal to 0.43), whereas Resinomer demonstrated the greatest significant overall microleakage (OR = 1.35). CONCLUSION: Within the experimental conditions of this in vitro study, thermal cycling significantly increased microleakage (OR = 8.04). The overall microleakage at the enamel margins was significantly lower than the overall microleakage at the cementum margins for the 4 luting agents tested (OR = 17.6).     

Effect of cooled composite inserts in the sealing ability of resin composite restorations placed at intraoral temperatures: an in vitro study

Polymerization shrinkage causes microleakage of resin composite restorations. New materials and operative techniques should be developed in order to reduce polymerization shrinkage. This research studied the effects of cooled composite inserts and room-temperature composite inserts in the sealing ability of resin composite restorations placed at intraoral temperatures. Forty-eight extracted human molars (providing a total of 155 sections) were kept at intraoral temperatures, and Class V cavities were restored with an ormocer-based resin composite (Admira, Voco). Three restorative techniques were used: conventional bulk insertion (Group I or control group) (n = 53 sections), room-temperature resin composite inserts (Group II) (n = 52) and cooled resin composite inserts (Group III) (n = 50). Microleakage and penetrating microleakage were studied under the microscope. Cooled composite inserts reduce microleakage at the gingival margins with respect to Groups I (p = 0.002) and II (p = 0.014). When small-size cooled composite inserts were used, the sealing ability at the gingival margins of Class V composite restorations was improved with respect to the bulk insertion technique and the room-temperature composite inserts technique.     

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.     

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.     

Shear bond strengths and microleakage of four types of dentin adhesive materials

The aim of this investigation was to compare the microleakage of composite resin (Z-100) and shear bond strength to bovine dentin using different types of adhesive systems (Scotch Bond Multi-Purpose, All-Bond 2, One-Step, and Perma Quick) to compare and correlate microleakage to shear bond strength. For the microleakage aspect of the study, 20 class V were prepared (bovine incisors) with 90-degree cavosurface margins and were located at the cemento-enamel junction using a template. Each dentin bonding system was applied to five cavities following the manufacturer's instructions and restored with Z-100 composite resin. After 24 hours of storage in distilled water at 37 degrees C, the teeth were immersed in 2% basic fuchsin dye. All teeth were sectioned in a mesiodistal direction using a diamond saw, and each section was then inspected under a stereomacroscope. For the shear bond strength aspect of the study, 20 bovine incisors were centrally horizontally mounted in Teflon mold with cold cure acrylic resin. Flat labial dentin surfaces were prepared using different grit silicon carbide abrasive wheels. Five specimens were used for each of the bonding agent systems. Each specimen was bonded with restorative composite resin (Z-100) and applied to the treated dentinal surface through a split Teflon mold. All specimens were stored in distilled water at 37 degrees C for 24 hours. The bonds were stressed using shear forces at a crosshead speed of 0.5mm/min using an Instron Universal testing machine. Findings indicate none of the systems tested in this study were free from microleakage. Scotch bond multi-purpose achieved the best seal, with One-Step being second best, while All-Bond 2 and Perma Quick had the poorest seal. However, there were significant differences among the shear bond strengths of the four bonding systems tested. Scotch Bond Multi-Purpose has a higher bond strength to composite resin when compared to the other dentin adhesives. The study also concluded there is no association between microleakage and shear bond strength.     

Effect of eccentric load cycling on microleakage of Class V flowable and packable composite resin restorations.

Class V composite restorations are subject to the stresses that induce non-carious cervical lesions. This study evaluated the effect of eccentric oblique load on microleakage of restorations. Class V cavities were randomly prepared on the buccal surfaces of 40 recently extracted premolars and restored with composite resin according to manufacturers' directions. Teeth were randomly assigned to one of four treatment groups with 10 teeth per group: (1) flowable resin (Revolution) without load cycling; (2) packable resin (Prodigy Condensable) without load cycling; (3) flowable resin with load cycling (200,000 cycles) and (4) packable resin with load cycling (200,000 cycles). All teeth were then immersed in 2% methylene blue solution for 24 hours after thermocycling (500 cycles). Dye penetration was measured (scores 0-3). The results indicated that adding load cycling significantly increased microleakage (p < 0.05). No significant differences in microleakage were observed for flowable resin vs packable resin. Gingival margins had significantly more microleakage (p < 0.05) than occlusal margins.     

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.