Microleakage of repaired class V silorane and nano-hybrid composite restorations after preparation with erbium:yttrium–aluminum–garnet laser and diamond bur

Investigation of the Er: YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities restored with different flowable composites

The purpose of this study was to evaluate the efficiency of the Er:YAG laser and diamond bur cavity preparation on the marginal microleakage of Class V cavities. Group 1: bur preparation (bp) + Vertise Flow (VF); Group 2: laser preparation (lp) + VF; Group 3: bp + Adper Easy One (AEO) + Filtek Ultimate Flowable Composite (FUFC); Group 4: lp + AEO + FUFC; Group 5: bp + Clearfil S3 Bond (CSB) + Clearfil Majesty Flow (CMF); Group 6: lp + CSB + CMF. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < .05). No significant difference was observed among all groups in terms of occlusal and cervical surfaces, respectively (p > .05). The use of the Er:YAG laser for cavity preparation with different adhesive systems and flowable composites did not influence microleakage.

Application of Laser Irradiation for Restorative Treatments

Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal hemorrhage, sterilization, healing of collagenic proteins, formation of a fibrous matrix, and inducing hard tissue barrier. Nevertheless, there are many controversies in literatures regarding their effects on the quality of bonded restorations. It hampered a wide application of lasers in some aspects of restorative dentistry and requirements to identify the best way to use this technology. The aim of this mini review is to explain special characteristics of laser therapy and to introduce the possible applications of laser devices for dental purposes.

Effect of different parameters of Er:YAG laser irradiations on class V composite restorations: A scanning electron microscopy study

The purpose of this study was to compare different parameters of Er:YAG laser irradiations on the marginal microleakage of Class V resin composite restorations. A total of 45 extracted premolars were selected for the study. Class V cavities prepared on both buccal and lingual surfaces of teeth by Er:YAG laser or bur and divided into nine groups. The occlusal margins were in enamel and the cervical margins were in cementum. Group-1: bur preparation; Group-2: laser preparation (lp) (600 mJ/5 Hz); Group-3: lp (300 mJ/10 Hz); Group-4: lp (200 mJ/15 Hz); Group-5: lp (150 mJ/20 Hz); Group-6: lp (200 mJ/20 Hz); Group-7: lp (300 mJ/14 Hz); Group-8: lp (400 mJ/10 Hz); Group-9: lp (700 mJ/5 Hz). All teeth were stored in distilled water at 37°C for 24 h, then thermocycled 1,000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation and two teeth for the scanning electron microscope (SEM) evaluation. Teeth, which were prepared for the microleakage test were immersed in 0.5% methylene blue dye for 24 h. After immersing, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05). More microleakage was observed in cervical regions compared to occlusal regions in all groups (p < 0.05) except for Group 6 (p > 0.05). No significant difference was observed among groups in terms of occlusal and cervical surfaces, separately (p > 0.05). It may be concluded that the cavities prepared by Er:YAG laser showed higher degree of microleakage than bur prepared at cervical regions. Different parameters of Er:YAG laser irradiations affected microleakage. SCANNING 38:434-441, 2016. © 2016 Wiley Periodicals, Inc.

The effects of cavity-filling techniques on microleakage in class II resin restorations prepared with Er:YAG laser and diamond bur: A scanning electron microscopy study

The purpose of this study was to investigate how two cavity-filling techniques affect microleakage in class II resin restorations prepared with Er:YAG laser and diamond bur. Standard MO and DO cavities were prepared in 20 extracted third molars, each randomly assigned to either Group-1 [Herculite XRV Ultra-bur-prepared cavity(bp)], Group-2 [Herculite XRV Ultra-laser-prepared cavity(lp)], Group-3 (SonicFill-(bp)], or Group-4 [SonicFill-(lp)]. For Groups 2 and 4, cavities were prepared by using an Er:YAG laser with a wavelength of 2.94 μm, output power of 200 mJ/pulse, and repetition rate of 20Hz. Teeth were restored with a one-step, self-etch adhesive material (OptiBond All-in-One), a nanohybrid composite (Herculite XRV Ultra), and a bulk-fill composite (SonicFill) according to the manufacturer's instructions. Five teeth from each group were chosen for microleakage investigation and two teeth for scanning electron microscope evaluation. Statistical analysis was performed by using Kruskal-Wallis test. Pair-wise comparisons were performed by Mann-Whitney U test with Bonferroni correction (p < 0.05). The statistical analysis of data revealed greater microleakage in cervical versus occlusal regions in all groups (P < 0.05). Group-2 yielded a higher degree of marginal leakage than Group-3 in terms of occlusal surfaces (p < 0.05). For cervical regions, a statistically significant difference was observed between Groups 2 and 3 as well as Groups 2 and 4 (p < 0.05). Group-3 exhibited significantly better marginal sealing than Group-1 in the cervical region (p < 0.05). The cavities prepared using an Er:YAG laser showed greater microleakage than those conventionally prepared using burs regardless of restorative material at both occlusal and cervical margins. SCANNING 38:389-395, 2016. © 2015 Wiley Periodicals, Inc.

Comparison of total-etch, self-etch, and selective etching techniques on class V composite restorations prepared by Er:YAG laser and bur: a scanning electron microscopy study

The purpose of this study was to compare total-etch, self-etch, and selective etching techniques on the marginal microleakage of Class V composite restorations prepared by Er:YAG laser and bur. Class V cavities prepared on both buccal and lingual surfaces of 30 premolars by Er:YAG laser or bur and divided into six groups. The occlusal margins were in enamel, and the cervical margins were in cementum. Group-1: bur preparation(bp)+Adper Single Bond 2 (ASB)+Filtek Z550 (FZ); Group-2: laser preparation(lp)+(ASB)+(FZ); Group-3: bp + Clearfil S3 Bond Plus (CSBP)+(FZ); Group-4: lp+(CSBP) (FZ); Group-5: bp + acid etching+(CSBP)+(FZ); Group-6: lp + acid etching+(CSBP)+(FZ). All teeth were stored in distilled water at 37°C for 24 hr, and then thermocycled 1000 times (5-55°C). Five teeth from each group were chosen for the microleakage investigation, and two teeth for the scanning electron microscope evaluation. Teeth which were prepared for the microleakage test were immersed in .5% methylene blue dye for 24 hr. After immersion, the teeth were sectioned and observed under a stereomicroscope for dye penetration. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p < .05). More microleakage was observed in the cervical regions compared to the occlusal regions in Groups 3, 5, and 6, respectively (p < .05). There is no statistically significant difference in Groups 1, 2, and 4, in terms of cervical regions versus occlusal regions (p > .05). No significant differences were observed among any groups in terms of occlusal and cervical surfaces, separately (p > .05). Different etching techniques did not influence microleakage of Class V restorations prepared by Er:YAG laser and bur.

Hydrolytic degradation of silorane- and methacrylate-based composite restorations: Evaluation of push-out strength and marginal adaptation

OBJECTIVES

This study compared the hydrolytic degradation of composite restorations based on methacrylate and silorane systems regarding bond strength and marginal adaptation. Materials and methods. Sixty bovine incisors were ground flat to obtain a 2-mm thick slice in which conical preparations were made. The specimens were randomly distributed into four groups (n = 15) according to the restorative system (silorane-Filtek LS/P90 adhesive; methacrylate-Filtek P60/Adper Easy Bond) and the degradation protocol (control: immediate evaluation; hydrolytic degradation: 6 months storage in water at 37°C). Marginal adaptation was evaluated using a dye staining technique. Digital images of the stained gaps were obtained to calculate the marginal gap (%), the ratio between the stained margins and the total length of the margin. Push-out bond strength test was conducted (0.5 mm/min). Marginal adaptation data was submitted to Kruskal-Wallis test and the bond strength data to two-way ANOVA/Tukey's test (α = 0.05). Results. The marginal adaptation was neither affected by the restorative system nor by the degradation protocol, although the number of perfect sealed reduced after 6 months. No significance was observed among the groups. No significance was noted between the silorane- and the methacrylate-based restorations for immediate bond strength. After the hydrolytic degradation, the silorane system showed higher bond strength then the methacrylate restorations. Conclusion. The silorane and methacrylate restorative systems produce restorations with similar immediate interfacial quality and 6 months of water storage does not cause significant bonding degradation for both systems. The silorane restorations show an increase in the bond strength after 6 months.

Effect of Different Adhesion Strategies on Bond Strength of Resin Composite to Composite-dentin Complex

Service life of discolored and abraded resin composite restorations could be prolonged by repair or relayering actions. Composite-composite adhesion can be achieved successfully using some surface conditioning methods, but the most effective adhesion protocol for relayering is not known when the composite restorations are surrounded with dentin. This study evaluated the effect of three adhesion strategies on the bond strength of resin composite to the composite-dentin complex. Intact maxillary central incisors (N=72, n=8 per subgroup) were collected and the coronal parts of the teeth were embedded in autopolymerized poly(methyl tfr54methacrylate) surrounded by a polyvinyl chloride cylinder. Cylindrical cavities (diameter: 2.6 mm; depth: 2 mm) were opened in the middle of the labial surfaces of the teeth using a standard diamond bur, and the specimens were randomly divided into three groups. Two types of resin composite, namely microhybrid (Quadrant Anterior Shine; AS) and nanohybrid (Grandio; G), were photo-polymerized incrementally in the cavities according to each manufacturer's recommendations. The composite-enamel surfaces were ground finished to 1200-grit silicone carbide paper until the dentin was exposed. The surfaces of the substrate composites and the surrounding dentin were conditioned according to one of the following adhesion protocols: protocol 1: acid-etching (dentin) + silica coating (composite) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); protocol 2: silica coating (composite) + acid-etching (dentin) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); and protocol 3: acid-etching (dentin) + primer (dentin) + silanization (composite) + bonding agent (dentin + composite). Applied primer and bonding agents were the corresponding materials of the composite manufacturer. Silica coating (CoJet sand, 30 μm) was achieved using a chairside air-abrasion device (distance: 10 mm; duration: four seconds in circular motion). After conditioning protocols, the repair resin was adhered to the substrate surfaces using transparent polyethylene molds (diameter: 3.6 mm) incrementally and photo-polymerized. The substrate-adherend combinations were as follows: AS-AS, G-G, AS-G. Shear force was applied to the adhesive interface in a Universal Testing Machine (crosshead speed: 1 mm/min). The types of failures were further evaluated and categorized as follows: 1) cohesive in the composite substrate and 2) adhesive at the interface. Bond strength values (MPa) were statistically analyzed using two-way analysis of variance and least significant difference post hoc tests (α=0.05). Significant effects of the adhesion strategy (p=0.006) and the composite type (p=0.000) were found. Interaction terms were not significant (p=0.292). Regardless of the substrate-adherend combination, protocol 1 (17–22 MPa) showed significantly higher results than did protocols 2 (15–17 MPa) and 3 (11–17 MPa) (p=0.028, p=0.002, respectively). The highest results were obtained from the G-G combination after all three protocols (17–22 MPa). The incidence of cohesive failures was more common when the substrate and the adherend were the same composite type (AS-AS: 87.5%, 87.5%, 75%; G-G: 100%, 75%, 50% for protocols 1, 2, and 3, respectively). When substrate and adherend were used interchangeably, adhesive failures were more frequent (25%, 50%, and 100% for protocol 1, 2, and 3, respectively). When the substrate and the adherend are of the same type, greater repair strength could be expected. In the repair of composites next to the dentin, depending on the composite type, conditioning the composite with silica coating and silanization after etching the dentin adds to the repair strength compared to the results obtained with silane application only.

Two-year interfacial bond durability and nanoleakage of repaired silorane-based resin composite

OBJECTIVES

To investigate the effect of silane primer application, intermediate adhesive agent/repair composite, and storage period on the interfacial microtensile bond strength (μTBS) of repaired silorane-based resin composite compared with unrepaired composites and on the nanoleakage.

METHODS

Forty-eight 1-month-old substrate specimens from Filtek P90 were roughened, etched, and distributed over two groups (n=24) based on receiving silane (Clearfil Ceramic Primer) or not. Then, half of the specimens (n=12) were repaired with P90 System Adhesive/Filtek P90 and the other half with Adper Scotchbond Multipurpose adhesive/Filtek Z250 resin composite. Within each repair category, repaired specimens were stored in artificial saliva at 37°C for either 24 hours (n=6) or two years before being serially sectioned into sticks (0.6 ± 0.01 mm(2)). From each specimen, two sticks were prepared for nanoleakage determination and four sticks were used for μTBS testing. Additional unrepaired specimens from each composite (n=12) were made to determine the cohesive strength at 24 hours and two years. Mean μTBS were calculated and statistically analyzed. Modes of failure were also determined.

RESULTS

General linear model analysis revealed no significant effect for the silane priming, intermediate adhesive agent/repair composite, and storage period or for their interactions on the μTBS values of the repaired specimens. There was no significant difference between the cohesive strength of Filtek P90 and Filtek Z250; both were significantly higher than all repaired categories. At 24 hours, nanoleakage was not detected when silorane-based composite was repaired with the same material. However, after two years, all repair categories showed nanoleakage.

CONCLUSIONS

Silane application has no effect on μTBS and nanoleakage. Durability of the interfacial bond of repaired silorane-based resin composite appeared successful regardless of the chemistry of the intermediate adhesive agent/composite used for repair. However, nanoleakage was detected early when a different repair intermediate adhesive agent/composite was used.

Effect of thermocycling on the bond strength of composite resin to bur and laser treated composite resin

The objective of this study was to investigate the effect of two different surface treatments (Er:YAG laser and bur) and three different numbers of thermal cycling (no aging, 1,000, 5,000, and 10,000 cycles) on the micro-shear bond strength of repaired composite resin. Ninety-six composite blocks (4 mm × 4 mm × 1 mm) obtained with a micromatrix hybrid composite were prepared. The composite blocks were then randomly divided into four groups (n = 24), according to the thermal cycling procedure: (1) stored in distilled water at 37°C for 24 h (control group), (2) 1,000 cycles, (3) 5,000 cycles, and (4) 10,000 cycles. After aging, the blocks were further subdivided into two subgroups (n = 12), according to surface treatment. Bur and laser-treated composite surfaces were treated with an etch&rinse adhesive system. In addition, a microhybrid composite resin was bonded to the surfaces via polyethylene tubing. Specimens were subjected to micro-shear bond strength test by a universal testing machine with a crosshead speed of 0 and 5 mm/min. The data were analyzed using one-way analysis of variance and Tukey tests (α = 0.05) for micro-shear bond strengths. After conducting a bond strength test, it was found that the laser and bur-treated specimens had similar results. Aging with 10,000 thermocycles significantly affected the repair bond strength of composite resins.