• Korean Journal of Dental Materials
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• v.44 no.2
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• pp.129-139
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• 2017

This study investigated the colors and mechanical properties of layered dental composites. Four nanocomposite resins (Aelite LS, Grandio, Tetric EvoCeram, Filtek Z350XT) and a silorane-based composite resin (P90) were used for overlying and underlying materials, respectively, with different thickness combinations. Colors, translucency parameter (TP), flexural and compressive properties were evaluated. All tested specimens had different color coordinates, although all were of A3 shade. Color coordinates and TP values of layered specimens better matched those of the corresponding overlying product as the thickness of the overlying product was increased. High TP values were related with high $b^*$ value differences between specimens (p<0.05). Both flexural strength and modulus, compressive strength and modulus of layered specimens with different thickness combinations were mostly lower than those of the corresponding overlying products, respectively, in their non-layered state.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.133-139
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• 2013

PURPOSE. This study was to evaluate the effect of the solution temperature on the mechanical properties of dualcure resin cements. MATERIALS AND METHODS. For the study, five dual-cure resin cements were chosen and light cured. To evaluate the effect of temperature on the specimens, the light-cured specimens were immersed in deionized water at three different temperatures (4, 37 and $60^{\circ}C$) for 7 days. The control specimens were aged in a $37^{\circ}C$ dry and dark chamber for 24 hours. The mechanical properties of the light-cured specimens were evaluated using the Vickers hardness test, three-point bending test, and compression test, respectively. Both flexural and compressive properties were evaluated using a universal testing machine. The data were analyzed using a two way ANOVA with Tukey test to perform multiple comparisons (${\alpha}$=0.05). RESULTS. After immersion, the specimens showed significantly different microhardness, flexural, and compressive properties compared to the control case regardless of solution temperatures. Depending on the resin brand, the microhardness difference between the top and bottom surfaces ranged approximately 3.3-12.2%. Among the specimens, BisCem and Calibra showed the highest and lowest decrease of flexural strength, respectively. Also, Calibra and Multilink Automix showed the highest and lowest decrease of compressive strength, respectively compared to the control case. CONCLUSION. The examined dual-cure resin cements had compatible flexural and compressive properties with most methacrylate-based composite resins and the underlying dentin regardless of solution temperature. However, the effect of the solution temperature on the mechanical properties was not consistent and depended more on the resin brand.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.1-11
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• 2020

Purpose: The purpose was to compare shear bond strength (SBS) of three types of resin for temporary restoration to polyetherketoneketone (PEKK) depending on surface modification. Materials and Methods: Sixty disks made from PEKK were air-abraded with 110 ㎛ alumina particles (Cobra, Renfert GmbH, Hilzinge, Germany) and thirty specimens were divided into two groups each: PEKK without Visio.link (Bredent, Senden, Germany)(U) and with Visio.link (P). Resins for temporary restoration (polymethylmethacrylate; PMMA, polyethylmethacrylate; PEMA, bis-acryl composite resin) in the shape of a square with one side 3.2 mm were bonded to PEKK twenty respectively and classified into six groups (UM, UE, UC, PM, PE and PC). All specimens were stored in distilled water at 37℃ for 24 hours. SBS of each group was measured at a crosshead speed of 2 mm/min in universal testing machine. SBS was compared using one-way ANOVA and a Tukey HSD test (P = 0.05). Results: Group UM and group UE showed a significant difference in SBS with group UC (P < 0.05). Group PC showed a significant increase in SBS than group UC (P < 0.05). Conclusion: It is recommended to apply Visio.link to PEKK for adhering bis-acrylic composite resin, but not for PMMA and PEMA in clinical practice.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.83-89
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• 2008

The purpose of this study was to evaluate the effect of the polymerization shrinkage and modulus of elasticity of composites on the cusp deflection of class V restoration in premolars. The sixteen extracted upper premolars were divided into 2 groups with similar size. The amounts of cuspal deflection were measured in Class V cavities restored with a flowable composite (Filtek flow) or a universal hybrid composite (Z-250). The bonded interfaces of the sectioned specimens were observed using a scanning electron microscopy (SEM). The polymerization shrinkage and modulus of elasticity of the composites were measured to find out the effect of physical properties of composite resins on the cuspal deflection. The results were as follows. 1. The amounts of cuspal deflection restored with Filtek flow or Z-250 were $2.18\;{\pm}\;0.92{\mu}m$ and $2.95\;{\pm}\;1.13\;{\mu}m$, respectively. Filtek flow showed less cuspal deflection but there was no statistically significant difference (p > 0.05). 2. The two specimens in each group showed gap at the inner portion of the cavity. 3. The polymerization shrinkages of Filtek flow and Z-250 were 4.41% and 2.23% respectively, and the flexural modulus of elasticity of cured Filtek flow (7.77 GPa) was much lower than that of Z-250 (17.43 GPa). 4. The cuspal deflection depends not only on the polymerization shrinkage but also on the modulus of elasticity of composites.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.184-193
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• 2016

Purpose: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. Materials and Methods: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. Results: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. Conclusion: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.225-226
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• 1998

치과용 복합레진으로 사용하기 위해서 새로운 다관능성 메타크릴레이트 유도체를 합성하였으며, 이 유도체와 기존의 Bis-GMA를 혼합하여 새로운 복합레진을 만들었다. 제조된 복합레진의 물리적 물성 및 생체친화성은 기존의 Bis-GMA control보다도 더 우수하였다.

• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.322-328
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• 2020

PURPOSE. This study evaluated the shear bond strength between 3D printed provisional resin and conventional provisional resin depending on type of conventional provisional resin and different surface treatments of 3D printed resin. MATERIALS AND METHODS. Ninety-six disc-shaped specimens (Ø14 mm × 20 mm thickness) were printed with resin for 3D printing (Nextdent C&B, Vertex-Dental B. V., Soesterberg, Netherlands). After post-processing, the specimens were randomly divided into 8 groups (n=12) according to two types of conventional repair resin (methylmethacrylate and bis-acryl composite) and four different surface treatments: no additional treatment, air abrasion, soaking in methylmethacrylate (MMA) monomer, and soaking in MMA monomer after air abrasion. After surface treatment, each repair resin was bonded in cylindrical shape using a silicone mold. Specimens were stored in 37℃ distilled water for 24 hours. The shear bond strength was measured using a universal testing machine at a crosshead speed of 0.5 mm/min. Failure modes were analyzed by scanning electron microscope. Statistical analysis was done using one-way ANOVA test and Kruskal-Wallis test (α=.05). RESULTS. The group repaired with bis-acryl composite without additional surface treatment showed the highest mean shear bond strength. It was significantly higher than all four groups repaired with methylmethacrylate (P<.05). Additional surface treatments, neither mechanical nor chemical, increased the shear bond strength within methylmethacrylate groups and bis-acryl composite groups (P>.05). Failure mode analysis showed that cohesive failure was most frequent in both methylmethacrylate and bis-acryl composite groups. CONCLUSION. Our results suggest that when repairing 3D printed provisional restoration with conventional provisional resin, repair with bis-acryl composite without additional surface treatment is recommended.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.249-266
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• 2004

The purpose of this study was to determine whether pH and time has any influence on the degradation behavior of composite restoration by analyzing the leached monomers of dental composites qualitatively and quantitatively after storage in acetate buffer solution as a function of time using high performance liquid chromatography (HPLC) / mass spectrometer. Materials and Methods：Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) with different matrix structure and filler composition were studied. Thirty specimens (7mm $diameter{\times}2mm$ thick) of each material were prepared. The cured materials were stored in acetate buffer solution at different pH (4, 7) for 1, 7 and 45days. As a reference, samples of unpolymerized composite materials of each product were treated with methanol (10mg/ml). Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, with literature data. and by their fragmentation patterns. Data were analysed statistically using ANOVA and Duncan's test. Results：1. Amounts of leached TEGDMA in Aeliteflo were significantly larger than those of UDMA in Z-250 and Heliomolar at experimental conditions of different storage time and pH variation (p<0.001). 2. As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in Z-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days, respectively (p<0.001). 3. In total amounts of all the leached monomers with storage times, the overall amounts of pH 4 extracts were larger than those of pH 7 extracts for all resin groups, but there was no significant difference (p>0.05).

• Restorative Dentistry and Endodontics
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• v.44 no.4
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• pp.37.1-37.10
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• 2019

Objectives: This study evaluated the bond strength of various fiberglass post cementation techniques using different resin-based composites. Materials and Methods: The roots from a total of 100 bovine incisors were randomly assigned to 5 treatment groups: G1, post + Scotchbond Multi-Purpose (SBMP) + RelyX ARC luting agent; G2, relined post (Filtek Z250) + SBMP + RelyX ARC; G3, individualized post (Filtek Z250) + SBMP; G4, individualized post (Filtek Bulk-Fill) + SBMP; G5, individualized post (Filtek Bulk-Fill Flow) + SBMP. The samples were subjected to the push-out (n = 10) and pull-out (n = 10) bond strength tests. Data from the push-out bond strength test were analyzed using 2-way analysis of variance (ANOVA) with the Bonferroni post hoc test, and data from the pull-out bond strength test were analyzed using 1-way ANOVA. Results: The data for push-out bond strength presented higher values for G2 and G5, mainly in the cervical and middle thirds, and the data from the apical third showed a lower mean push-out bond strength in all groups. No significant difference was noted for pull-out bond strength among all groups. The most frequent failure modes observed were adhesive failure between dentine and resin and mixed failure. Conclusions: Fiberglass post cementation using restorative and flowable bulk-fill composites with the individualization technique may be a promising alternative to existing methods of post cementation.

• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.25-33
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• 2017

Purpose: The aim of this study was to evaluate accuracy of glass fiber mesh complete denture of before and after curing. Methods: Edentulous model was selected as the master model. Ten study models were made by Type IV stone. Wax complete dentures were produced by the denture base and artificial teeth. CD and GD groups were measured six measurement distance before curing. The wax complete denture was investment after measurement is completed. Using a heat polymerization resin was injected resin. After injecting the resin it was curing. A complete denture was re-measured after curing. The measured data was verified by paired t-test. Results: Overall CD group was larger the value of the measured length. In the CD group, A-D point was larger. The smallest point was the B-D point. However, there was no statistically significant difference only C-D point(p>0.05). In the GD group, A-B point was larger. but B-D point was the smallest. A-D and B-C statistically points showed significant differences(p<0.05). Conclusion: Glass fiber mesh resin complete denture can be clinically applied to the edentulous patient.