Marginal quality and microleakage of adhesive class V restorations

OBJECTIVES: The aim of this in vitro study was to determine the marginal quality and microleakage of composite resin class V restorations. METHODS: Standardized mixed class V cavities (diameter: 4mm, depth: 2mm) with half of the finish lines limited within dentin were cut in 90 freshly extracted human molars and randomly assigned to nine groups (n=10). After etching enamel and dentin, the cavities were restored with nine different restorative systems (Syntac Sprint/Tetric Ceram=SS, Syntac Single-Component/Tetric Ceram=SC, Onestep/Aeliteflo=OS, Aquaprep+Onestep/Aeliteflo=OA, Prime & Bond 2.1/TPH=PB, Optibond Solo/Prodigy=OP, Singlebond/Z100=SB, Tenure Quik/Marathon=TQ, Solobond M/Arabesk=SM) using a wet-bonding procedure. After finishing and polishing, the teeth were stored for 24h in distilled water at 37 degrees C before they were subjected to thermocycling (5/55 degrees C, 1000x). Epoxy replicas were made for margin analysis in the SEM. Specimens were stained in methylene blue, sectioned, and evaluated for microleakage. Dye penetration was scored on a 0-3 ordinal scale. RESULTS: Statistical analysis (Kruskal-Wallis H-test, Mann-Whitney U-test) revealed significant differences (P<0.05) among the groups at dentin and enamel margins for the microleakage scores as well as for the results of the quantitative SEM margin analysis. SC revealed a significantly higher percentage of perfect margins in the SEM than OS and SM in enamel and dentin, respectively. OA exhibited significantly more leakage in enamel than all other groups. CONCLUSIONS: None of the tested restorative systems achieved a perfect seal in dentin and enamel of mixed class V cavities. Marginal quality and sealing ability of adhesive systems to dentin, using a wet-bonding procedure, is still inferior compared with enamel margins.     

Polymerization stress related to radiant exposure and its effect on microleakage of composite restorations

Objectives

Verify the influence of radiant exposure (dose) on polymerization stress and microleakage of composite restorations using two adhesive systems.

Methods

An experimental composite (1BisGMA:1TEGDMA, 75 wt.% filler) was subjected to 3, 6, 12 or 24 J/cm² under 500 mW/cm². Stress was measured in 1-mm height specimens placed between two glass rods (Ø = 5 mm) attached to a testing machine. Microleakage was assessed in cylindrical restorations (Ø = 5 mm, h = 2 mm) with enamel margins, using Adper Single Bond 2 (SB) or Adper Prompt (PR). After storage, specimens were subjected to dye penetration (50% AgNO₃) and sectioned twice, perpendicularly. Microleakage of the 8 tooth/composite interfaces was recorded in millimeters. KHN was measured at both surfaces of cylindrical specimens (Ø = 5 mm, 1 or 2 mm height). ANOVA/Tukey test were used (α = 0.05). KHN top and bottom were compared using paired t-tests.

Results

Stress increased significantly with dose (3 J/cm²: 1.4 ± 0.3^c; 6 J/cm²: 4.3 ± 0.5^b; 12 J/cm²: 9.3 ± 0.6^a; 24 J/cm²: 9.9 ± 0.7^a, in MPa). For both average and maximum microleakage, interactions were not statistically significant (p > 0.05). Tooth average microleakage was influenced by the adhesive system (SB < PR) and increased with dose (3 J/cm² < 6 J/cm² = 12 J/cm² = 24 J/cm²). Tooth maximum microleakage was influenced by dose only (3 J/cm² < 6 J/cm² = 12 J/cm² = 24 J/cm²). A direct association between stress and microleakage was suggested with SB, while with PR showed severe dye penetration at all doses evaluated. KHN showed significant differences among all groups, except at bottom of 2 mm specimens cured with 3 and 6 J/cm². Differences between top and bottom were found for 2 mm specimens cured with 3 and 6 J/cm².

Conclusions

Stress and microleakage increased significantly with the applied radiant exposure.     

The effect of rebonding on microleakage of class V aesthetic restorations

This in vitro study evaluated the effect of rebonding on microleakage of a resin composite, a condensable resin and two polyacid-modified resin composite restorations. Standardized cylindrical Class V dentin cavities were prepared on the buccal root surfaces of 240 extracted bovine incisive teeth. The prepared teeth were randomly assigned to four groups of 60 teeth and restored with the following restorative systems: I--(ZS) Z100/Scotchbond Multi-Purpose Plus; II--(SS) Solitaire/Solid Bond; III--(FS) Freedom/Stae; IV--(FSB) F200/Single Bond. Thirty teeth of each group were rebonded with a low-viscosity resin (Fortify/BISCO), according to the manufacturer's instructions. The remaining teeth received no treatment. All teeth were thermocycled for 5,000 cycles and brushed by hand three times a day for 10 days using a toothbrush and a slurry of dentifrice and water. Specimens were stained in a 2% methylene blue solution and longitudinally sectioned with diamond disks. Microleakage was scored on a scale of 0 to 3. The Kruskal-Wallis test showed statistically significant differences among the groups (h=156.54; alpha<0.05). Pairwise comparison by means of the least significant difference showed that (SS) and (FS) with or without rebonding were not statistically different from each other. These groups showed the highest microleakage differences from (ZS) and (FSB) with or without rebonding. (ZS) with rebonding showed the lowest microleakage that was not statistically different from (ZS) without rebonding and (FSB) with rebonding.     

Polymerization shrinkage and contraction stress of dental resin composites

OBJECTIVE: The aim of this study was to evaluate the shrinkage, contraction stress, tensile modulus, and the flow factor of 17 commercially available dental resin composites. METHOD: The volumetric shrinkage measurements were performed by mercury dilatometry, and the contraction stress and tensile modulus were determined by means of stress-strain analysis. The statistical analysis was conducted by ANOVA and Tukey's post hoc test, and linear regression. RESULTS: Strong linear correlation for most resin composites were found for (i) contraction stress and shrinkage (ii) contraction stress and tensile modulus, and (iii) shrinkage and tensile modules. For most of the materials the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. The pre-polymerized clusters in Heliomolar results in improved shrinkage/contraction stress properties. The shrinkage/contraction stress for Filtek Z100, Aelite Flo, and Flow-it was too high for the amount of resin in the resin composite. This was rationalized by high polymerization rates, a flow factor, and the nature of the resin. SIGNIFICANCE: High shrinkage and/or high contraction stress may lead to failure of the bond between the resin composites and the tooth structure. This study shows that the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. Therefore, using pre-polymerized clusters will improve shrinkage/contraction stress properties, as was shown in Heliomolar, while high polymerization rates, and low flow factors have a deteriorative effect on the shrinkage/contraction stress properties.     

The effect of occlusal loading on the microleakage of class V restorations

OBJECTIVE: This in vitro study evaluated the microleakage of Class V cavities restored with a resin composite and different adhesive systems after occlusal loading. METHODS & MATERIALS: Standardized box-shaped Class V cavities were prepared on the buccal side of 135 non-carious human premolars. The teeth were randomly divided into three groups of 45 premolars each and restored as follows: Group 1-two-step total-etch adhesive (Single Bond, 3M) + resin composite (Supreme, 3M ESPE); Group 2-two-step self-etch adhesive (Clearfil SE, Kuraray) + resin composite and Group 3-one-step self-etch adhesive (Xeno III, Dentsply) + resin composite. The restorations were finished with aluminum oxide discs (Sof-Lex, 3M). Fifteen teeth in each group received 10,000 x 100 N and 250 N occlusal loads, respectively, and the remaining 15 teeth served as the control. The premolars were immersed in 2% methylene blue for 24 hours. The dye penetration was examined under a stereomicroscope, and the results were statistically analyzed by Kruskal Wallis, Mann-Whitney U and Wilcoxon Signed Rank tests to determine differences between the groups. RESULTS: Gingival margins showed more dye penetration than occlusal margins in all the tested groups (p<0.05). In all the tested adhesive systems, 100 N occlusal loading did not change dye penetration; however, Groups 1 and 2 exhibited better marginal sealing than Group 3 at the enamel margins under 250 N occlusal loading. CONCLUSION: Within the limitations of this in vitro study, it may be concluded that enamel margins provided better marginal sealing than dentin/cementum margins and the two-step self-etch adhesive exhibited better marginal sealing than an all-in-one adhesive at the enamel margins under 250 N occlusal loading.     

可流动复合树脂充填楔状缺损的体外微渗漏研究

目的　研究可流动复合树脂充填楔状缺损离体牙模型的边缘微渗漏情况。方法　选择因正畸拔除的上颌前磨牙2 4个,于颊侧颈部釉牙骨质界处备V型洞后,随机分为3组,分别采用Aelieteflo可流动复合树脂,DyractAP复合体,GICTYPEII化学固化玻璃离子进行充填。经力循环、热循环后,2 %亚甲基蓝染色2 4h ,将每个牙齿自颊舌向沿长轴连续切3片。体视显微镜放大4 0倍观察充填体边缘染液渗漏情况。结果　3组间充填体微渗率差异有显著性(P <0 .0 0 1) ,以Aelieteflo材料的边缘微渗率最低(P <0 .0 5 )。3组牙合侧壁与龈侧壁微渗率间差异无显著性(P =0 .2 6 3)。结论　可流动复合树脂用于楔状缺损充填可以获得较好的边缘封闭性。     

Influence of different light sources on microleakage of class V composite resin restorations

The aim of this study was to evaluate the effect of three different curing units on microleakage of class V composite restorations. Class V cavities were prepared on the buccal surfaces of 45 extracted premolar teeth. The teeth were randomly divided into three groups of 15 each. A conventional halogen curing unit (Hilux 350), a high intensity halogen curing unit (Optilux 501) and plasma arc curing unit (Power Pac) were used to polymerize composite resin (Vitalesence). After restoration, the teeth were thermocycled for 100 cycles between 5 degrees and 55 degrees C using a dwell time of 30 s and exposed to a dye. Results showed that there was no significant difference among three different curing units (P > 0.05), however the microleakage at the dentin margins was greater than the enamel margins (P < 0.05). Clinical relevance: Plasma arc curing or fast halogen units cure composite materials at a faster rate than conventional curing units because of the high light intensity. High intensity halogen curing units and plasma arc curing units might be useful alternatives in composite polymerization. Therefore, these units are suggested for clinical use to save chair side time.     

Assessing microleakage of different class V restorations after Er:YAG laser and bur preparation

This study assessed in vitro marginal leakage of class V cavities prepared by turbine and Er:YAG laser and restored with different materials. Sixty cavities with enamel and dentine margins were prepared and assigned to six groups: I, II, III by turbine and IV, V, VI by Er:YAG laser. The following restorative systems were used: groups I and IV: Bond 1 + Alert; II and V: Fuji II LC; III and VI: SBMP + Dispersalloy. After finishing, specimens were thermocycled for 8 h and 45 min (500 cycles), isolated, immersed in a 0.2% Rhodamine B solution, sectioned oro-facially and analysed for leakage. The dye penetration means (%) were: occlusal I: 10.09 (+/- 21.28), II: 3.25 (+/- 10.27), III: 0, IV: 41.77 (+/- 42.48), V: 23.37 (+/- 33.79), VI: 12.66 (+/- 24.06); cervical I: 16.49 (+/- 26.67), II: 4.34 (+/- 13.71), III: 0, IV: 37.71 (+/- 30.47), V: 39.56 (+/- 43.35) and VI: 72.53 (+/- 37.79). The use of Er:YAG laser for cavity preparation yielded higher degree of marginal leakage, as compared with the use of conventional air-turbine. The enamel interface provided better marginal sealing, comparing with dentine/cementum margin. As to the cavity preparation device (i.e. laser or bur), the analysis of the results showed that bonded amalgam and Fuji II LC provided less infiltration, than Alert. On the other hand, for lased cavities, Alert provided the best results, similar to those of Fuji II LC and superior to those reached by bonded amalgam.     

The effect of two different polishing techniques on microleakage of new composites in Class V restorations

AIM: The purpose of this study was to investigate the effect of polishing systems on the microleakage of a nanofill, a nanohybrid, and a microhybrid composite in Class V cavities. METHODS AND MATERIALS: Preparations were made at the cemento-enamel junction (CEJ) of 36 extracted human premolars. The teeth were randomly divided into three groups and restored with new resin composites according to the manufacturers' instructions as follows: Group 1, Filtek Supreme & Single Bond; Group 2, Grandio & Solobond; and Group 3, Artemis & Excite. The restorations were finished with diamond finishing burs. The restored/finished teeth were randomly divided into two groups and polished using the following systems: Super-Snap (Al2O2 coated, abrasive disc system, fine grit, and extra fine grit) and Astropol/Astrobrush (silicon-based abrasive polisher point and polisher brush). All specimens were thermocycled 1000 times with a 10 second dwell time. They were immersed in 0.5% aqueous basic fuchsin dye for 24 hours and then sectioned buccal-lingual-longitudinally through the center of both restorations of each tooth and evaluated under a stereomicroscope at 30X magnification. The degree of dye penetration was quantified. RESULT: No significant difference in leakage scores was observed in enamel margins (p=0.456, Kruskall Wallis test), but dentin margins were significantly affected by the different polishing systems (p=0.037, Kruskall Wallis test). The lower leakage scores were recorded for Astropol/Astrobrush polishing systems. The nanofill composite showed the least leakage among the test groups in this study. The most leakage was observed in nanohybrid composite resin (p<0.05, Mann Whitney U test). CONCLUSIONS: Under the conditions of this in vitro study: the microleakage resistance of composites at enamel margins is not significantly affected by the different polishing systems; the lowest leakage scores were recorded for Astropol/Astrobrush polishing techniques in different types of composites; and the ranking of the composite materials from most to least leakage at the dentin margins according to polishing techniques was Grandio >Artemis > Filtek Supreme.     

Early marginal microleakage in class II resin composite restorations

The aim of this study was to evaluate in vitro the early marginal microleakage around conventional and sandwich Class II (MOD) restorations. Ten different combinations of dentin bonding agents, glass-ionomer cements, and posterior resin composites were used. Class II cavities were prepared in freshly extracted third molars whose root surfaces had previously been coated. All gingival margins were prepared at the cementum-enamel junction. Teeth were filled by use of a multi-incremental technique, finished with discs, and immediately immersed in 2% erythrosin B for 12 h at 37 degrees C. Three transverse sections were made at 0.5 mm, 2 mm, and 3.5 mm over the cementum-enamel margin and evaluated under a stereomicroscope. Microleakage was scored linearly along the dentin/enamel-restoration interface. Sections at the cementum-enamel level showed significantly higher microleakage than the other two. Significant differences were observed between the various combinations of materials. Early marginal microleakage in Class II restorations depends not only on filling technique and on dentin bonding systems but also on the resin composite. Glass-ionomer cements significantly reduce early marginal microleakage in Class II restorations.     

Photoelastic determination of polymerization shrinkage stress in low-shrinkage resin composites

Low-shrinkage resin composites are in the focus of research in posterior resin composite restoratives. The aim of the study was to examine the polymerization shrinkage stress of new composites (Venus Diamond/ Heraeus Kulzer; SDR/DENTSPLY) and an experimental low-shrinkage resin composite (Ormocer/VOCO) in comparison to established low-shrinkage resin composites (Filtek Silorane/ 3M ESPE; els/Saremco; Filtek Supreme XT/3M ESPE; Clearfil Majesty Posterior/Kuraray). Cylindrical cavities (? 4 mm) in Araldit-B epoxy resin plates (40×40×4 mm) were pretreated with the Rocatec system to ensure bonding of the resin composites. The resin composite specimens (n = 10) were exposed to light for 60 s with a QTH curing device (Translux energy, Heraeus Kulzer, Germany). The samples were stored dark and dry (23 °C). Polymeri-zation shrinkage stress data (MPa) 4 min and 24 h post exposure were calculated based on the diameter of the first-order isochromatic rings, obtained from the Araldit plates. The statistical analysis of the obtained data was carried out with the Wilcoxon test (p = 0.05). After 24 h, the following mean stress values and standard deviations were obtained: Venus Diamond 3.4 ± 0.27 MPa; SDR 3.3 ± 0.26 MPa; exp. Ormocer 4.0 ± 0.18 MPa; Filtek Silorane 2.8 ± 0.19 MPa; els 2.5 ± 0.09 MPa; Filtek Supreme XT 6.0 ± 0.20 MPa; and Clearfil Majesty Posterior 5.6 ± 0.15 MPa. For all materials, higher polymerization stress values were recorded after 24 h. All differences in the shrinkage data obtained after 24 h were statistically significant (p < 0.05) except Venus Diamond/SDR. Venus Diamond, els and SDR showed shrinkage data closer to that of Filtek Silorane.     

Effect of aluminum chloride hemostatic agent on microleakage of class V composite resin restorations bonded with all-in-one adhesive

Objectives: Since hemostatic agents can induce changes on enamel and dentin surfaces and influence composite resin adhesion, the aim of the present study was to evaluate the effect of the aluminum chloride hemostatic agent on the gingival margin microleakage of class V (Cl V) composite resin restorations bonded with all-in-one adhesive. Study design: Cl V cavities were prepared on the buccal surfaces of 60 sound bovine permanent incisors. Gingival margins of the cavities were placed 1.5 mm apical to the cemento-enamel junction (CEJ). The teeth were randomly divided into two groups of 30. In group 1, the cavities were restored without the application of a hemostatic agent; in group 2, the cavities were restored after the application of the hemostatic agent. In both groups all-in-one adhesive and Z250 composite resin were used to restore the cavities with the incremental technique. After finishing and polishing, the samples underwent a thermocycling procedure, followed by immersion in 2% basic fuschin solution for 24 hours. The samples were sectioned and gingival microleakage was evaluated under a stereomicroscope. The non-parametric Mann-Whitney U test was used to compare microleakage between the two groups. Statistical significance was defined at P<0.05. Results: A statistically significant difference was observed in microleakage between the two groups (P<0.001). Conclusions: Contamination of Cl V composite resin restorations bonded with all-in-one adhesive with aluminum chloride hemostatic agent significantly increases restoration gingival margin microleakage.     

Polymerization contraction force of packable composites

The maximum rate of shrinkage force development and maximum contraction force was evaluated for four packable composites and a hybrid composite control. One of the packable composites demonstrated a significantly higher maximum force rate and maximum force than the other materials; the three remaining packable composites had maximum force rates and maximum forces that were statistically similar to the conventional hybrid composite control.