• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.89-96
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• 2018

Purpose: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bis-acryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. Materials and Methods: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. Results: The highest shear bond strength ($17.54{\pm}3.14MPa$) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. Conclusion: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.436-444
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• 2018

The purpose of this study was to compare the shear bond strengths of 3-in-1 flowable composite to the enamel and dentin of primary teeth to previous adhesive systems. 110 primary incisors were prepared and divided into two groups: Dentin group included 5 groups: 1) Scotch bond Multi-purpose plus(DSM), 2) Single-bond 2(DSB), 3) Clearfil SE bond(DSE), 4) All bond universal(DAB), 5) Constic(DC), and Enamel group included 6 groups: 1) Scotch bond Multi-purpose plus(ESM), 2) Single bond 2(ESB), 3) Clearfil SE bond(ESE), 4) All bond universal(EAB), 5) Constic(EC), 6) Constic with additional etching(ECE). A cylinder of composite was bonded to the prepared surface, and the shear bond strength was measured. In the dentin groups, group DC had significantly lower shear bond strength than group DSE. No significant difference was found between group DC, group DSM, group DSB and group DAB. In the enamel groups, there was no significant difference between group EC, group ESE, and group EAB. This material showed lowest shear bond strength among all tested materials in both enamel and dentin groups, showing insignificant difference with some adhesive systems. Therefore, 3-in-1 flowable composite can be used for primary teeth restoration but further studies are needed.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.359-367
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• 2019

For this study, specimens were prepared using five types of composite resin and resin-reinforced glass ionomer Fuji II LC, and 29 days precipitation was done in four kinds of solution, which were soy sauce, gochujang, wine, and distilled water. Ten specimens for each coloring sample were divided into two groups, one those surfaces was polyester film and the other with 1200-grit abrasive paper, and 20 specimens per materials. Color change (${\Delta}{\ast}ab$) in the colored specimens is measured in 2days, 7days, 14days and 29days using spectrophotometer (CM-2600d, Konica, Minolta, Ramsey, NJ). All values were considered significant when P<0.05. 1. Each material is discolored over time under the influence of different storage solutions. 2. In soy source, among the specimens polished with polyester film, color change was observed in resin-modified glass ionomer Fuji II LC, prodigy and compomer F-2000 on day 2. Meanwhile, Fuji II LC showed noticeable color change in specimens prepared with 1200-grit sandpaper on day 2, which was followed by flowable resin on day 7. 3. On day 2, there was a color change with the specimens of flowable resin, resin-modified glass ionomer Fuji II LC and Prodigy among the hybrid specimen in the groups of polyester film in gochujang.

• Restorative Dentistry and Endodontics
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• v.48 no.3
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• pp.30.1-30.11
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• 2023

Objectives: This study verified the possibility of cementing fiberglass-reinforced posts using a flowable bulk-fill composite (BF), comparing its push-out bond strength and microhardness with these properties of 3 luting materials. Materials and Methods: Sixty endodontically treated bovine roots were used. Posts were cemented using conventional dual-cured cement (CC); self-adhesive cement (SA); dual-cured composite (RC); and BF. Push-out bond strength (n = 10) and microhardness (n = 5) tests were performed after 1 week and 4 months of storage. Two-way repeated measures analysis of variance (ANOVA), 1-way ANOVA, t-test, and Tukey post-hoc tests were applied for the push-out bond strength and microhardness results; and Pearson correlation test was applied to verify the correlation between push-out bond strength and microhardness results (α = 0.05). Results: BF presented higher push-out bond strength than CC and SA in the cervical third before aging (p < 0.01). No differences were found between push-out bond strength before and after aging for all the luting materials (p = 0.84). Regarding hardness, only SA presented higher values measured before than after aging (p < 0.01). RC and BF did not present 80% of the maximum hardness at the apical regions. A strong positive correlation was found between the luting materials' push-out bond strength and microhardness (p < 0.01, R² = 0.7912). Conclusions: The BF presented comparable or higher push-out bond strength and microhardness than the luting materials, which indicates that it could be used for cementing resin posts in situations where adequate light curing is possible.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.69-79
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• 2007

The purpose of this study was to investigate the effects of composite resin restorations on the stress distribution of notch shaped noncarious cervical lesion using three-dimensional (3D) finite element analysis (FEA). Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072 ; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid or flowable resin and each restoration was simulated with adhesive layer thickness ($40{\mu}m$) A static load of 500 N was applied on a point load condition at buccal cusp (loading A) and palatal cusp (loading B). The principal stresses in the lesion apex (internal line angle of cavity) and middle vertical wall were analyzed using ANSYS. The results were as follows 1. Under loading A, compressive stress is created in the unrestored and restored cavity. Under loading B, tensile stress is created. And the peak stress concentration is seen at near mesial corner of the cavity under each load condition. 2. Compared to the unrestored cavity, the principal stresses at the cemeto-enamel junction (CEJ) and internal line angle of the cavity were more reduced in the restored cavity on both load con ditions. 3. In teeth restored with hybrid composite, the principal stresses at the CEJ and internal line angle of the cavity were more reduced than flowable resin.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.3
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• pp.440-447
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• 2009

This study was performed to compare the wear resistance of sealant and flowable resins for analyzing the effect of flowable resin as a sealant in preventive resin restorations. Specimens were made and Vicker's hardness number and surface roughness were measured. SEM observations of the polished and abraded surfaces were established. Kruskal-Wallis rank test and Mann-Whitney U test at the significant level of ${\alpha}$=0.05 were used. The following results were obtained: 1. The microhardness was decreased among groups in following order: Z350 (3M ESPE, U.S.A), Estelite (Tokuyama Dental, Japan) and Ultraseal (Ultradent, U.S.A). There were significant differences in all groups (p<0.0001). 2. The surface roughness was decreased among groups in following order: Ultraseal XT plus, Palfique Estelite LV and Filtek Z350 flowable. However, there is no statistically significant differences in roughness among Estellite, Z350 and Ultraseal at the significance level of ${\alpha}$=0.05, with p=0.116 3. SEM observation of the unworn and worn surfaces revealed the qualitative differences in the wear appearance among groups. The results in this study indicate that flowable resin is better than sealant in aspect of physical properties.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.27-32
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• 2013

Purpose: The aims of this study were to evaluate the effect of a resin coating on the shear bond strength of indirect composite restoration bonded to dentin with a self adhesive resin cement and to compare the shear bond strength with that of a conventional resin cement. Materials and methods: The occlusal enamels of thirty six extracted noncarious human molars were removed until the dentin flat surfaces of the teeth were exposed. Then, they were divided into 3 groups. The dentin surfaces of group 1 and 3 were left without any conditioning, while the dentin surfaces of group 2 were resin-coated with Clearfil SE bond and a flowable resin composite, Metafil Flo. After all specimens were temporized for 24 hours, indirect composite resin blocks fabricated by Tescera were bonded to dentins by Unicem for group 1 and 2, and by Panavia F for group 3. After 48 hours of water storage, shear bond strengths were measured. The data was analyzed with one-way analysis of variance and multiple comparison test (Tukey method). Results: The shear bond strengths of Unicem applied to resin coated dentin surfaces were significantly higher than those of Unicem and Panavia F used to uncoated dentin surfaces (P<.0001). Conclusion: Application of a resin coating to the dentin surface significantly improved the shear bonding strength of a self adhesive resin cement in indirect restoration.

• Restorative Dentistry and Endodontics
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• v.27 no.4
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• pp.394-402
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• 2002

2급 복합레진 수복 와동의 치은 변연이 상아질 상에 있을 때 유동성 레진 이장의 유무와 두께가 미세누출에 미치는 영향을 알아보기 위해 본 실험을 시행하였다. 60개의 발거된 대구치의 근, 원심면에 각각 협설측 3mm, 치은벽 깊이 1mm의 2급 와동을 형성하고 치은 변연은 법랑-백아 경계에서 약 1mm 하방에 위치 시켰다. 모든 와동을 32% 인산으로 15초 처리 및 30초 수세 후 Prime & Bond$^{\circledR}$ NT 상아질 접착제를 적용하였고, Tetric Ceram(TC), Tetric Flow(TF)를 이용하여 다음의 6가지 군으로 나누어 수복하였다. (1) TC로 수평 적층 충전, (2) TC로 수직 적층 충전, (3) 0.5-1mm두께로 TF 이장 후 TC로 수평적층 충전, (4) 0.5-1mm 두께로 TF 이장 후 TC로 수직 적층 충전, (5) 2-3mm 두께로 TF 이장 후 TC로 수평적층 충전, (6) 2-3mm두께로 TF이장 후 TC로 수직 적층 충전. 충전된 시편을 37$^{\circ}C$ 100% humidity에서 24시간 보관하고 5$^{\circ}C$와 55$^{\circ}C$에서 500회의 열순환을 실시하여 치은 변연의 0.5mm 외부에 nail varnish를 도포 하여 2% methylene blue 용액에 12시간 침잠시켰다. 시편을 아크릴릭 레진에 매몰하여 수복물의 중앙에서 종절단 한 후 입체현미경하에서 색소의 침투도를 관찰하여 다음과 같은 결과를 얻었다. 유동성 레진의 이장을 시행한 군과 하지 않은 군간에 미세누출은 유의차를 보이지 않았다(p>0.05) 유동성 레진의 두께에 따른 미세누출의 차이는 나타나지 않았다(p>0.05) 경사면 충전법을 시행한 군에서는 유동성 레진을 이장한 군들이 이장하지 않은 군보다 유의하게 많은 누출을 보였다(p<0.05). 수평적층 충전법을 시행한 군에서는 유동성 레진 이장이 미세누출에 유의한 차이를 보이지 않았다(p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.4
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• pp.383-388
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• 2012

The aim of this study was to compare the compressive strength and the surface microhardness of Beautifil flow (Shofu, Kyoto, Japan) with $Filtek^{TM}$ Z350, Z350XT (3M ESPE, USA). Fifteen specimens from each material were fabricated for testing. Compressive strength was measured by using a universal testing machine at a crosshead speed of 1 mm/min. Surface microhardness values were measured by using Vickers hardness tester under 4.9 N load and 10 seconds dwelling time. The compressive strength of Group 2 $Filtek^{TM}$ Z350XT shows the highest value as $218.7{\pm}18.4$ MPa and Group 1 $Filtek^{TM}$ Z350 was $205.5{\pm}27.1$ MPa. Group 3 Beautifil flow F00 was $176.5{\pm}30.3$ MPa, and Group 4 Beautifil flow F10 was $173.4{\pm}26.2$ MPa. The compressive strength of Group 2 is higher than Group 3 and 4 (p < 0.05). The surface microhardness of Group 2 $Filtek^{TM}$ Z350XT shows the highest value as $39.1{\pm}2.1$ and Group 4 Beautifil flow F10 was $27.9{\pm}1.8$. And Group 3 Beautifil flow F00 was $23.1{\pm}1.1$, Group 1 $Filtek^{TM}$ Z350 was $20.4{\pm}0.9$. There was a statistical significant difference in surface microhardness between all groups (p < 0.05). In conclusion, the compressive strength of giomer was below the level of flowable composite resin. However, the surface microhardness of giomer is comparable to that of flowable composite resin. Giomer would be the good alternative to composite resin, if there is improvement of the compressive strength of giomer.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.18.1-18.13
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• 2021

Composite resins are the most commonly used dental restorative materials after minimally invasive dental procedures, and they offer an aesthetically pleasing appearance. An ideal composite restorative material should have wear properties similar to those of tooth tissues. Wear refers to the damaging, gradual loss or deformation of a material at solid surfaces. Depending on the mechanism of action, wear can be categorized as abrasive, adhesive, fatigue, or corrosive. Currently used composite resins cover a wide range of materials with diverse properties, offering dental clinicians multiple choices for anterior and posterior teeth. In order to improve the mechanical properties and the resistance to wear of composite materials, many types of monomers, silane coupling agents, and reinforcing fillers have been developed. Since resistance to wear is an important factor in determining the clinical success of composite resins, the purpose of this literature review was to define what constitutes wear. The discussion focuses on factors that contribute to the extent of wear as well as to the prevention of wear. Finally, the behavior of various types of existing composite materials such as nanohybrid, flowable, and computer-assisted design/computer-assisted manufacturing materials, was investigated, along with the factors that may cause or contribute to their wear.