• The Journal of Korean Academy of Prosthodontics
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• v.31 no.3
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• pp.385-393
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• 1993

Injection processing of denture base resin was introduced by Pryer in 1942, in an attempt to reduce processing shrinkage. More recently a continuous-pressure injection type technique has been developed (SR-Ivocap, Ivoclar AG, Schaan, Liechtenstein.), and it reduced processing error and increased resin density. The purpose of this study was to compare tensile bond strength of heat-cured, cold-cured, and light-cured denture base resin bonded to continuous-pressure injection type resin. To know it, 60 cylindrical resin specimens were fabricated, and tensile bond strength were measured. The results were as follows : 1. The mean tensile bond strength bonded to continuous-pressure injection type resin was lower than bonded to conventional heat cured resin. But tensile bond strength of conventional heat cured resin bonding with light cured resin was lower than continuous-pressure injection type resin. 2. Of the tensile bond strength bonded to continuous-pressure injection type resin, tensile bond strength bonding with continuous-pressure injection type resin was the greatest(but not significantly different from bonding with conventional heat cured resin), followed by cold-cured, light-cured resin. 3. Of the tensile bond strength bonded to conventional heat cured resin, tensile bond strength bonding with conventional heat cured resin was the greatest and followed by continuous-pressure injection type resin, cold-cured resin, light-cured resin. According to these results, bonding of continuous-pressure injection type resin with conventional heat cured resin or continuous-pressure injection type resin is acceptable, but bonding with light-cured resin is questionable.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.163-169
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• 2020

The purpose of this study was to identify the degree of awareness and need for dental health insurance of parents with children under 12 years of age, and provide it as basic data for the development of the dental health insurance system in the future. It was conducted with 158 parents who are raising children under the age of 12 in Busan and Gyeongnam areas. In the case of mothers(p=.001), the higher the age (p=.005), the higher the experience of sealant. In the case of mothers, the knowledge of sealant (p=.012) was high. When the gender was female (p=.026), the parenting relationship was mother (p=.006), and regularly engaged in vocational activities (p=.003), the awareness of resin filling was high, and the experience was the child's age (p=. 004) was higher, the higher the knowledge was when the parenting relationship was mother (p=.024). The factors influencing the satisfaction of sealant were found to be the parents education level (p=.004), the awareness of the sealant (p=.003), and the experience (p=.011). From the above research results, more active publicity is needed to increase the awareness and experience of parents' health insurance.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.72-81
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• 2017

The aim of this study was to evaluate the effectiveness of artificial saliva contamination and decontamination procedures at different stages of a bonding procedure on the microtensile bond strength (MTBS) of two one-step self-etch adhesives and a two-step total-etch adhesive to dentin of primary teeth. Forty-two extracted sound primary molars were randomly divided into three groups depending on three adhesives, Scotchbond Universal Adhesive (SBU), All-Bond Universal (ABU) and Prime & Bond NT (PNT). For each adhesive, the teeth were allocated into seven groups. Except for control group, group 1, the groups were contaminated with artificial saliva at three different stages: the groups 2 and 3 - before adhesive application; the groups 4 and 5 - before adhesive polymerization; the groups 6 and 7 - after adhesive polymerization. Decontaminating procedures were rinsing, air-drying (group 2, 4, 6) and air-drying (group 3, 5, 7). The specimens were restored with composite resin (Filtek, Z350) and microtensile bond strength was measured. The data was analyzed with one-way ANOVA and Tukey HSD test (p < 0.05). In the control group, using PNT resulted in significantly higher bond strength than when ABU and SBU were used (p < 0.001). For three adhesives, the groups 2, 4 and 6 had greater bond strength than the groups 3, 5 and 7. Also, when the artificial saliva was contaminated before adhesive polymerization (group 4, 5), it showed a significantly lower bond strength. Generally the two-step total-etch adhesive generated a higher bond strength than the one-step self-etch adhesive. Artificial saliva contamination before adhesive polymerization led to a drastic decrease in bond strength, and rinsing with water followed by air-drying could not recover the bond strength.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.177-184
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• 2020

Purpose: The purpose of this study was to compare and evaluate the tensile bond strength of chairside reline resin to denture base resin fabricated by different methods (subtractive manufacturing, additive manufacturing, and conventional heat-curing). Materials and methods: Denture base specimens were fabricated as cuboid specimens with a width of 25 mm × length 25 mm × height 3 mm by subtractive manufacturing (VITA VIONIC BASE), additive manufacturing (NextDent Base) and conventional heat-curing (Lucitone 199). After storing the specimens in distilled water at 37℃ for 30 days and drying them, they were relined with polyethyl methacrylate (PEMA) chairside reline resin (REBASE II Normal). The subtractive and additive manufacturing groups were set as the experimental group, and the heat-curing group was set as the control group. Ten specimens were prepared for each group. After storing all bound specimens in distilled water at 37℃ for 24 hours, the tensile bond strength between denture bases and chairside reline resin was measured by a universal testing machine at a crosshead speed of 10 mm/min. The fracture pattern of each specimen was analyzed and classified into adhesive failure, cohesive failure, and mixed failure. Tensile bond strength, according to the fabrication method, was analyzed by 1-way ANOVA and Bonferroni's method (α=.05). Results: Mean tensile bond strength of the heat-curing group (2.45 ± 0.39 MPa) and subtractive manufacturing group (2.33 ± 0.39 MPa) had no significant difference (P>.999). The additive manufacturing group showed significantly lower tensile bond strength (1.23 ± 0.36 MPa) compared to the other groups (P<.001). Most specimens of heat-curing and subtractive manufacturing groups had mixed failure, but mixed failure and adhesive failure showed the same frequency in additive manufacturing group. Conclusion: The mean tensile bond strength of the subtractive manufacturing group was not significantly different from the heat-curing group. The additive manufacturing group showed significantly lower mean tensile bond strength than the other two groups.

• 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.

• Restorative Dentistry and Endodontics
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• v.34 no.3
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• pp.199-207
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• 2009

The objective of this study was to evaluate the effect of color measuring instrument by measuring the color of dental composite resins. Nine shade light cured composite resin disks were prepared (diameter : 15 mm, thickness : 4 mm). CIE $L^*a^*b^*$ color scale of each disk was measured with 3 different types of spectrophotometer [MiniScan XE plus (Model 4000S, Hunter Lab, USA), CM-3500d (Minolta, Japan) and Specbos 2100 Miniature VIS Reflection spectrometer (Serial No: 319416, JETI Technishe VIS Instrumentic GmbH. Germany)]. Miniscan XE Plus and CM-3500d using identical measuring geometry with different size of viewing aperture. But Specbos 2100 using different measuring geometry. Within the limitation of this study, there were color difference (${\Delta}E^*$) from 2.4 to 7.8 between Miniscan XE Plus and CM-3500d, but $L^*$, $a^*$, $b^*$ values showed the high correlation. However, there were great color difference (${\Delta}E^*$) in the extent of about 20 between instruments with the different measuring geometry. Therefore, color scale measured by color measuring instrument should be used as a relative value rather than an absolute value in the field of dentistry.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.377-387
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• 2006

The objective of this study was to evaluate the influence of multiple adhesive coatings on the thickness of hybrid and adhesive layer and shear bond strength(SBS) of self-etch adhesives and self-etch primer adhesives. The buccal or lingual crown dentin of extracted human molars was used. Self-etch adhesives or self-etch primer adhesives were applied 1, 2 and 3 times on the dentin before light curing. In another group adhesives were reapplied after light curing first layer. Treated surfaces were prepared to measure the thickness of hybrid and adhesive layer with SEM, and shear bond strength to dentin using an Instron machine. The following results were obtained : 1. The adhesive layers increased with the number of coatings(p<0.05) with all adhesives. Adpor Prompt L-Pop and Xeno III were significantly thinner than self-etch primer adhesives (p<0.05). 2. The thickness of hybrid layers increased with the number of coatings (p<0.05). 3. The shear bonding strength of Unifil Bond and Clearfill SE Bond were higher than Scotchbond Multipurpose Plus and Adpor Prompt L-Pop (p<0.05), and similar with Xeno III. 4. The shear bond strength increased significantly with the number of coatings in Adpor Prompt L-Pop(p<0.05), but decreased at 3 times in AdheSE Bond(p>0.05). 5. In Adpor Prompt L-Pop and Xeno III, the shear bond strength decreased when adhesives were reapplied after curing the first adhesive layer.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.1
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• pp.1-15
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• 2021

Additive manufacturing (AM) for dental materials can produce more complex forms than conventional manufacturing methods. Compared to milling processing, AM consumes less equipment and materials, making sustainability an advantage. AM can be categorized into 7 types. Polymers made by vat polymerization are the most suitable material for AM due to superior mechanical properties and internal fit compared to conventional self-polymerizing methods. However, polymers are mainly used as provisional restoration due to their relatively low mechanical strength. Metal AM uses powder bed fusion methods and has higher fracture toughness and density than castings, but has higher residual stress, which requires research on post-processing methods to remove them. AM for ceramic use vat polymerization of materials mixed with ceramic powder and resin polymer. The ceramic materials for AM needs complex post-processing such as debinding of polymer and sintering. The low mechanical strength and volumetric accuracy of the products made by AM must be improved to be commercialized. AM requires more research to find the most suitable fabrication process conditions, as the mechanical properties and surface of any material will vary depending on the processing condition.

• Restorative Dentistry and Endodontics
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• v.32 no.4
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• pp.377-384
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• 2007

Present tooth bonding system can be categorized into total etching bonding system (TE) and self-etching boding system (SE) based on their way of smear layer treatment. The purposes of this study were to compare the effectiveness between these two systems and to evaluate the effect of number of themocycling on microleakage of class V composite resin restorations. Total forty class V cavities were prepared on the single-rooted bovine teeth and were randomly divided into four experimental groups: two kinds of bonding system and another two kinds of thermocycling groups. Half of the cavities were filed with Z250 following the use of TE system, Single Bond and another twenty cavities were filled with Metafil and AQ Bond, SE system. All composite restoratives were cured using light curing unit (XL2500, 3M ESPE, St. Paul, MN, USA) for 40 seconds with a light intensity of $600mW/cm^2$. Teeth were stored in distilled water for one day at room temperature and were finished and polished with Sof-Lex system. Half of teeth were thermocycled 500 times and the other half were thermocycled 5,000 times between $5^{\circ}C$ and $55^{\circ}C$ for 30 second at each temperature. Teeth were isolated with two layers of nail varnish except the restoration surface and 1 mm surrounding margins. Electrical conductivity (${\mu}A$) was recorded in distilled water by electrochemical method. Microleakage scores were compared and analyzed using two-way ANOVA at 95% level. From this study, following results were obtained: There was no interaction between variables of bonding system and number of thermocycling (p = 0.485). Microleakage was not affected by the number of thermocycling either (p = 0.814). However, Composite restoration of Metafil and AQ Bond, SE bond system showed less microleakage than composite restoration of Z250 and Single Bond, TE bond system (p = 0.005).

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.203-210
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• 2011

Objectives: The purpose of this study was to evaluate the effect of various application methods of one-step self-etch adhesives to microtensile resin-dentin bond strength. Materials and Methods: Thirty-six extracted human molars were used. The teeth were assigned randomly to twelve groups (n = 15), according to the three different adhesive systems (Clearfil Tri-S Bond, Adper Prompt L-Pop, G-Bond) and application methods. The adhesive systems were applied on the dentin as follows: 1) The single coating, 2) The double coating, 3) Manual agitation, 4) Ultrasonic agitation. Following the adhesive application, light-cure composite resin was constructed. The restored teeth were stored in distilled water at room temperature for 24 hours, and prepared 15 specimens per groups. Then microtensile bond strength was measured and the failure mode was examined. Results: Manual agitation and ultrasonic agitation of adhesive significantly increased the microtensile bond strength than single coating and double coating did. Double coating of adhesive significantly increased the microtensile bond strength than single coating did and there was no significant difference between the manual agitation and ultrasonic agitation group. There was significant difference in microtensile bonding strength among all adhesives and Clearfil Tri-S Bond showed the highest bond strength. Conclusions: In one-step self-etching adhesives, there was significant difference according to application methods and type of adhesives. No matter of the material, the manual or ultrasonic agitation of the adhesive showed significantly higher microtensile bond strength.