Yusuf Ziya Bayindir

Effect of water storage on the translucency of silorane-based and dimethacrylate-based composite resins with fibres

OBJECTIVES The purposes of this study were (1) to determine the translucency of silorane and dimethacrylate-based composite resins and (2) to evaluate the effect of water storage and reinforcement with fibre on the translucency of composite resins. METHODS Two light-cured composite resins (A2 shade), Filtek Silorane (silorane-based composite) and Valux Plus (dimethacrylate-based composite), were used in this study. The first group was used as the control with no reinforcements, the second was reinforced with polyethylene (Ribbond THM) and the third was reinforced with a glass fibre (Everstick Net) for each composite resin. Colour measurements were measured against white and black backgrounds with a Shadepilot (Degu Dent Gmbh, Hanau, Germany) spectrophotometer and recorded under a D65 light source, which reflects daylight. CIELAB parameters of each specimen were recorded at baseline and at 24 h, 168 h and 504 h. Translucency of materials was calculated using the translucency parameter (TP) formula. Data were analyzed using repeated measures ANOVA and LSD post hoc tests (α=0.05). RESULTS The highest baseline TP value was in the Valux Plus/non-fibre reinforced group (14.06±1) and the lowest in the Filtek Silorane/Ribond THM group (8.98±1.11). Repeated measures ANOVA revealed significant effects from the factors storage time, composite resin, composite resin×storage time and fibre×time (p=0.047; p=0.001; p=0.013; p=0.022, respectively). CONCLUSION Within the limitations of the study, we concluded that inclusion of polyethylene and glass fibres did not alter the translucency of the different-based composite resins. The longest storage time resulted in the greatest change in translucency values of Filtek Silorane composite resins. CLINICAL SIGNIFICANCE Considering the translucencies of composites with different formulations in the selection of composite resins for aesthetic restorations is important in terms of obtaining optimal aesthetic outcomes.

Comparing the shear bond strength of direct and indirect composite inlays in relation to different surface conditioning and curing techniques

Objective: The aim of this study was to test the null hypothesis that different surface conditioning (etch and rinse and self-etch) and curing techniques (light cure/dual cure) had no effect on the shear bond strength of direct and indirect composite inlays. Materials and Methods: A total of 112 extracted human molar teeth were horizontally sectioned and randomly divided into two groups according to restoration technique (direct and indirect restorations). Each group was further subdivided into seven subgroups (n = 8) according to bonding agent (etch and rinse adhesives Scotchbond multi-purpose plus, All-Bond 3, Adper Single Bond and Prime Bond NT; and self-etch adhesives Clearfil Liner Bond, Futurabond DC and G bond). Indirect composites were cemented to dentin surfaces using dual-curing luting cement. Shear bond strength of specimens was tested using a Universal Testing Machine. Two samples from each subgroup were evaluated under Scanning electron microscopy to see the failing modes. Data was analyzed using independent sample t-tests and Tukey′s tests. Results: Surface conditioning and curing of bonding agents were all found to have significant effects on shear bond strength (P < 0.05) of both direct and indirect composite inlays. With direct restoration, etch and rinse systems and dual-cured bonding agents yielded higher bond strengths than indirect restoration, self-etch systems and light-cured bonding agents. Conclusions: The results of the present study indicated that direct restoration to be a more reliable method than indirect restoration. Although etch and rinse bonding systems showed higher shear bond strength to dentin than self-etch systems, both systems can be safely used for the adhesion of direct as well as indirect restorations.

Quality of curing in relation to different light sources by measuring hardness, degree of conversion and depth of cure

Abstract This study was to determine the quality of curing of second generation light emitting diode (LED-II) compared to a first generation LED (LED-I) and conventional halogen (quartz tungsten halogen) light curing unity by measuring depth of cure, degree of polymerisation and surface hardness. Filtek Z-250 hybrid composite resin (3M-ESPE, Germany), with shade A2, was used in this study. One quartz tungsten halogen/light curing unit (LCU) (Hilux, Benlioglu Dental, Turkey), one LED-I-LCU unit (Elipar Freelight 3M-ESPE, Germany) and one LED-II-LCU (Elipar Freelight, 3M-ESPE, Germany) were used for polymerisation of the composite resin. The depth of cure was obtained with scrape test, degree of cure was measured with Fourier transform infrared spectrometer (Spectrum-One, Perkin-Elmer, USA) and surface hardness was calculated with surface hardness tester (Micromet-2001, Buehler, Dusseldorf, Germany). The data were analysed by Kruskal Wallis and Mann Whitney-U. The polymerisation depth of LED-I-LCU was significantly lower than that of the other LCUs (p<0·05). However, no significant differences were obtained among all tested systems in point of degree of cure and surface hardness at 2 mm depth. Within the limitations of this study, although LED-I showed lower depth of cure, all tested systems appear suitable for routine clinical practice for polymerisation of the composite resin.

Color changes in resin cement polymerized with different curing lights under indirect restorations

Aim: The aim of the study was to investigate the effects of different interface materials and curing units on color changes in a resin cement material. Materials and Methods: Three interface materials and different curing systems, quartz-tungsten-halogen and polywave and monowave light-emitting diode (LED) light curing units, were studied at two-time intervals. Polystyrene strip was used as a control group. All measurements were made on a white background for standard color measurement. According to the CIE LFNx01aFNx01bFNx01 color space, the baseline color values of each specimen were measured. Differences between the measurements were calculated as ΔE, ΔL, Δa, and Δb. Data were analyzed using analysis of variance (ANOVA) and Duncan′s tests (α = 0.05) with SPSS 20.0 software (SPSS Inc., Chicago, IL, USA). ANOVA revealed significance for interface materials and curing units and time for ΔE (P < 0.05). Results: Interaction between polymerizing units, material and time was not significant (P > 0.05). Monowave LED exhibited significantly higher color changes than the other units ([P < 0.05] [ΔE 2.94 ± 0.44]). QTH promoted composite specimens significantly less color change ([P < 0.05] [ΔE 0.87 ± 0.41]). Conclusion: This study concluded that color of resin cement used in the adhesion of indirect restorations was affected by curing device light and indirect restoration material type.

Temperature rise during polymerization of different cavity liners and composite resins

Objective: The purpose of this study was to evaluate the thermal insulating properties of different light curing cavity liners and composite resins during light emitting diode (LED) curing. Materials and Methods: Sixty-four dentin discs, 1 mm thick and 8 mm in diameter, were prepared. Specimens were divided into four groups. Calcium hydroxide (Ca[OH]2), resin-modified glass ionomer cement, flowable composite and adhesive systems were applied to dentin discs according to the manufacturers’ instructions. The rise in temperature during polymerization with a LED curing unit (LCU) was measured using a K-type thermocouple connected to a data logger. Subsequently, all specimens were randomly divided into one of two groups. A silorane-based composite resin and a methacrylate-based composite resin were applied to the specimens. Temperature rise during polymerization of composite resins with LCU were then measured again. Data were analyzed using one-way ANOVA and post hoc Tukey analyses. Results: There were significant differences in temperature rise among the liners, adhesives, and composite resins (P < 0.05). Silorane-based composite resin exhibited significantly greater temperature rises than methacrylate-based resin (P < 0.05). The smallest temperature rises were observed in Ca(OH)2 specimens. Conclusion: Thermal insulating properties of different restorative materials are important factors in pulp health. Bonding agents alone are not sufficient to protect pulp from thermal stimuli throughout curing.

Temperature changes caused by light curing of fiber-reinforced composite resins

Objective: The aim of the study is to evaluate temperature change in fiber-reinforced composite (FRC) resin photopolymerized with a light-emitting diode (LED) light-curing unit (LCU). Materials and Methods: Forty dentine disks (1 mm thick and 8 mm diameter) were prepared from human molars. The FRC specimens (2 mm thickness and 8 mm diameter) consisted of polyethylene fiber (Construct (CT)) products or glass fiber (ever Stick (ES)) and one hybrid composite bonded to the dentin disks and polymerized with an LED LCU. Control groups were prepared using the hybrid composite. Temperature rise in dentine samples under the FRC bonded disks was measured using a K-type thermocouple, and data were recorded. Temperature change data were subjected to analysis of variance (ANOVA) and Duncans test. Results: The results show that addition of fiber (one or two layers) did not change temperature rise values at any of the exposure times (P > 0.05). The CT fiber/two layer/40 s group exhibited the greatest temperature rise (5.49 ± 0.62) and the ES/one layer/10 s group the lowest rise (1.75 ± 0.32). A significant difference was observed in temperature rise measured during 10 and 20 s exposures (P < 0.05). Conclusion: Maximal temperature rise determined in all groups was not critical for pulpal health, although clinicians need to note temperature rises during polymerization.

A comparison of dentin bond strength and degree of polymerization of bulk-fill and methacrylate-based flowable composites

Objective: This study aimed to evaluate the dentin bond strength and degree of polymerization of bulk-fill and methacrylate-based flowable composites. Materials and Methods: Dentin bond strength of composites was evaluated using the microtensile bond strength (μTBS) test. Five different composites were applied on flat dentin surfaces with self-etch and etch-and-rinse adhesives. Twenty microspecimens with a 1 mm2 cross-sectional area were prepared for each group (n = 20). The μTBS test was then applied. To measure the degree of polymerization of composites, eight cylindrical blocks were prepared (n = 8) from each composite. The surface microhardness of each composite was measured on the bottom and top surfaces, and a hardness ratio (HR) was calculated. Data were analyzed using one-way ANOVA and the Tukeys honestly significant difference test (α = 0.05). Results: According to the μTBS test results, the SDR Etch-and-Rinse group exhibited the highest dentin bonding strength and the Aelita self-etch group exhibited the lowest (P < 0.05). HR measurement showed that all composite groups had a sufficient degree of polymerization at a 2-mm thickness, while only the SDR and Xtra-Base groups had sufficient polymerization at a 4-mm thickness. Conclusions: Bulk-fill composite demonstrates an even higher degree of polymerization of methacrylate-based flowable composite when applied in a 4-mm thickness.

Caries detector dyes: Do they stain only the caries?

Objective: Caries detector (CD) dyes aid in caries diagnosis by staining the organic matrix of less mineralized infected dentine. However, detector dyes are not specific to bacteria and can discolor surrounding healthy tissues as dentino-enamel junction or the circumpulpal dentine. Possible discoloring effect of CD dye over restorative materials have not been evaluated until date. The aim of this study was to investigate the staining effects of four commercial CD dyes Caries Detector (CAD), Caries Marker (CAM),SEEK (SEE), Sable Seek (SES) on a variety of tooth colored restorative materials; Filtek Valux Plus (VLX), Filtek Z250 (Z25), Filtek Silorane (SIL) Fuji IX (FUJ). Materials and Methods: A total of 40 disc-shaped specimens were prepared from each restorative material. After 24 h distilled water storage, baseline color was measured according to the Commission International de l′Eclairage LFNx01 aFNx01 bFNx01 system by using a reflection spectrophotometer. Each CD dye was applied to 10 samples of each composite group for 10 s and applications were repeated for 2 times. Before the final color measurements, all samples was rinsed and dried. Color differences (ΔE) were measured and analyzed the data with two-way analysis of variance and Tukey honest significant difference post-hoc tests. Results: Independent of dyes, perceptible color changes were observed in glass ionomer restorative material (FUJ) (ΔE ab FNx01 > 3.3). CAD, CAM and SES caused staining on highly triethylene glycol dimethacrylate monomer containing composite resin (VLX). Silorane based restorative material (SIL) and micro hybrid resin composite (Z25) were more resistant to discoloration then VLX and FUJ (P < 0.05). Conclusion: CD dyes may cause discolorations in some restorative materials and should be used with maximum care.

Influence of different bonding systems and soft start polymerisation on marginal gap formation: stereological approach

Abstract The aim of the present paper was to investigate the effects of soft start polymerisation and the influence of the different adhesive systems on marginal gap formation using a stereological approach. Three adhesive systems [Single Bond (SB), Scotchbond Multi-Purpose (SM) and Clearfil SE Bond (SE)] and two curing techniques (standard cure and soft cure) were studied. For every curing technique, 24 cylindrical class V dentin cavities, 3 mm in diameter and 2 mm thick, were prepared and restorated with 3M Valux Plus composite resin using three different dentin bonding agents. Marginal gap formation was investigated under scanning electron microscope (SEM). On the micrographs, the surface areas of the gaps were measured according to the modified Cavalieri method. Data were analysed by ANOVA and Duncan multi-comparison tests (α=0˙05). Statistical analysis of variance (ANOVA) presented statistical significance for two factors: curing techniques and adhesives (p<0˙05). Interactions between adhesives and curing technique was not found significantly important (p>0˙05). With the relation averages, The Duncan test was carried out at the 5% level of significance. Soft cure has showed significantly less marginal gap formation in all adhesive systems. Clearfil SE Bond with soft cure has showed significantly less marginal gap formation, whereas Scotchbond MP with standard cure had higher values in all test groups (p<0˙05).