• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.110-117
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• 2019

Purpose: This study was to evaluate the wear resistance of 3D printed, milled, and conventionally cured provisional resin materials. Materials and methods: Four types of resin materials made with different methods were examined: Stereolithography apparatus (SLA) 3D printed resin (S3P), digital light processing (DLP) 3D printed resin (D3P), milled resin (MIL), conventionally self-cured resin (CON). In the 3D printed resin specimens, the build orientation and layer thickness were set to $0^{\circ}$ and $100{\mu}m$, respectively. The specimens were tested in a 2-axis chewing simulator with the steatite as the antagonist under thermocycling condition (5 kg, 30,000 cycles, 0.8 Hz, $5^{\circ}C/55^{\circ}C$). Wear losses of the specimens were calculated using CAD software and scanning electron microscope (SEM) was used to investigate wear surface of the specimens. Statistical significance was determined using One-way ANOVA and Dunnett T3 analysis (${\alpha}=.05$). Results: Wear losses of the S3P, D3P, and MIL groups significantly smaller than those of the CON group (P < .05). There was no significant difference among S3P, D3P, and MIL group (P > .05). In the SEM observations, in the S3P and D3P groups, vertical cracks were observed in the sliding direction of the antagonist. In the MIL group, there was an overall uniform wear surface, whereas in the CON group, a distinct wear track and numerous bubbles were observed. Conclusion: Within the limits of this study, provisional resin materials made with 3D printing show adequate wear resistance for applications in dentistry.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.209-216
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• 2021

Purpose: The purpose of this study is to compare the shear bond strength of resin cement for orthodontic brackets without applying an adhesive primer, to the case of applying an adhesive primer. Materials and Methods: The specimens were divided into three experimental groups, Transbond XT, GC Ortho Connect and Orthomite LC, and the enamel surface was divided into two sections, one with 37% phosphoric acid and the other with 37% phosphoric acid and an adhesive primer or universal adhesive. Each of three types of cement was applied to orthodontic bracket, and after bonding, the shear bond strength was measured. Results: Transbond XT and Orthomite LC significantly increased shear bond strength when orthodontic brackets were bonded after applying an adhesive primer and universal adhesive, respectively. Conclusion: It is expected that application of an adhesive primer or universal adhesive after acid etching will improve shear bond strength of orthodontic brackets in Transbond XT and Orthomite LC.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.101-110
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• 2021

Purpose: In this study, we intended to study the change in bond strength according to the thermal cycling of provisional resin and 3D printed resin for making provisional restoration. Materials and Methods: Through DLP method, 3D printed resin powder was used to produce 3D printed resin samples. The samples were grouped into eight groups, according to types of provisional resin (PMMA, bis-acryl resin) which is to be bonded on the samples and numbers of thermal cycling (control, 2,000, 3,000, 5,000 cycles). Shear bond strength of the bonded samples was measured on the universal testing machine. Results: As the number of thermal cycling increased, the shear bond strength of PMMA and bis-acryl resin for 3D printed resins decreased except between 3,000 cycles and 5,000 cycles in PMMA groups. In the PMMA group, there were significant differences in shear bond strength between less number than 3,000 cycles (P < 0.05) and no significant differences between more number than 3,000 cycles (P > 0.05). In the bis-acryl resin group, there were significant differences in shear bond strength between control and 2,000 cycles, control and 3,000 cycles, and control and 5,000 cycles (P < 0.05), no significant difference between 2,000 and 3,000 cycles, between 3,000 and 5,000 cycles (P > 0.05). Conclusion: The shear bond strength between 3D printed resin and provisional resin tended to decrease after thermal cycling.

• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.605-611
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• 1995

The purpose of this study was to evaluate effects of time on shear bond strengths of a light-cured glass ionomer cement and chemically cured resin cement to enamel, and to observe the failure patterns of bracket bondings. Shear bond strength of a light-cured glass ionomer cement were compared with that of a resin cement. Metal brackets were bonded on the extracted human bicuspids. Specimens were subjected to a shear load(in an Instron machine) after storage at room temperature for 5 and 15 minutes; after storage in distilled water at $37^{\circ}C$ for 1 or 35 days. The deboned specimens were measured In respect of adhesive remnant index. The data were evaluated and tested by ANOVA, Duncan's multiple range test, and t-test, and those results were as follows. 1. The shear bond strength of light-cured glass ionomer cement is higher than that of resin cement at 5 and 15 minutes. 2. The shear bond strengths of both light-cured glass ionomer cement and resin cement increase with time. There was no significant difference in those of both 1 day group and 35 day group 3. Light-cured glass ionomer cement is suitable as orthodontic bracket adhesives

• 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.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.309-314
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• 2020

Polymethyl methacrylate (PMMA) is concerned with promoting oral infection due to its low antibacterial activity. To overcome this, the nanoparticles of Ag-MSN, nGO, and CNP were mixed with MMA liquid in a weight ratio of 0, 0.25, 0.5, 1.0, 2.0% compared to resin powder using Orthocryl from Dentarum, a calibration resin, and then instructed by the manufacturer. Accordingly, a specimen for calibration was prepared by mixing PMMA: MMA (1.2: 1) ratio, and physical properties of the calibration resin, antifungal experiments, and statistical analysis were performed. As a result of antibacterial experiments, the antibacterial properties of Ag-MSN increased. In nGO, the antibacterial adhesive effect increased hydrophilicity, not a change in surface roughness. The higher the CNP concentration, the higher the antibacterial activity. This suggests its potential usefulness as an antibacterial dental material for orthodontic devices and temporary restorations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.147-147
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• 2004

폴리메틸메타크릴레이트(polymethylmethacrylate, PMMA)는 아크릴레이트계 고분자이자 열가소성 플라스틱으로써 LCD용 도광판, 콘택트렌즈, 치과용 레진, DVD 디스크용 소재, 나노임프린트용 피가공재, 나노리소그래피 공정용 레지스트 등 많은 분야에서 활발히 사용되고 있다. PMMA 와 같은 점소성 점탄성 소재의 기계적 성질 측정 및 가공을 위해서는, 응력완화 (stress relaxation), 크립 (creep)등과 같은 시간의존적 변형거동에 대한 연구가 선행되어야 한다.(중략)

• Polymer(Korea)
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• v.33 no.2
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• pp.153-157
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• 2009

The resin matrix in the dental composite is generally composed of 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propoxy) phenyl] propane (Bis-GMA) as a base resin and triethylene glycol dimethacrylate (TEGDMA) as a diluent for the reduction of viscosity. The applications of dental composite were often limited in dentistry due to the relatively large amounts of volumetric shrinkage during polymerization and water uptake caused by the addition of TEGDMA to the resin matrix. In this study, in order to solve problems stemmed from the TEGDMA by reducing amount of diluent added to resin matrix, diethylene glycol dimethacrylate (DEGDMA) and ethylene glycol dimethacrylate (EGDMA) were explored as new diluents. A decrease in the volumetric shrinkage and an increase in the mechanical strength were observed by replacing TEGDMA in the dental composite to DEGDMA (or EGDMA). Reduction in the mechanical strength of the dental composite containing DEGDMA (or EGDMA), was not serious in comparison with that of the dental composite containing TEGDMA after water uptake.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.280-289
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• 2004

Adequate polymerization is a crucial factor in obtaining optimal physical properties and clinical performance of resin composite restorative materials. The purpose of this study was to determine the effectiveness of shade and depth on dental composite resin polymerized with plasma arc curing unit employing FTIR and microhardness. From this experiment, the following results were obtained : 1. The light transmission and microhardness by mode 6 in plasma arc curing were similar to by 20 secs in halogen light curing. 2. The experimental groups of A1, A2, A3, A3.5 were not signifcant difference to light transmission and microhardness on surface and 2mm depth, but were significant difference on 3mm and 4mm depth. Especially light transmission and microhardness were small in darker shade and deeper thickness. 3. Compared with depth cure, uncured monomer amount increased at more than 2mm depth. 4. The light transmission by FTIR and polymerization by microhardness were significant corelation.

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.419-427
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• 2008

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement. Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration, Variolink-II (Ivoclar-Vivadent) : Exite DSC, Panavia-F (Kuraray) : ED-Primer, RelyX Unicorn (3M ESPE) Single- Bond, Duolink (Risco) : One-step, Mulitlink (Ivoclar-Vivadent) : Multilinh Primer. Shear bond strength was measured by Instron universal testing machine. Adhesive application improved shear bond strength (p<0.05) But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application. With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.