• The Journal of Korean Academy of Prosthodontics
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• v.31 no.1
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• pp.11-18
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• 1993

Autopolymerising and visible light cured resin are used to reline dentures. But relined surface are easily contaminated by water or saliva in the mouth during clinical procedure. This study was to find out the effect of surface contamination on the transverse strength of the relined denture base. To accomplish this, the specimens of $65\times10\times3mm$ were made with heat-cured(Lucitone 199), visible light-cured(Triad), and autopolymerizing resin(Kooliner). Measurements of transverse strength were taken for each specimen. Specimens made of heat-cured resins, sizing $65\times10\times1.5mm$, were relined with heat-cured, light-cured, and autopolymerizing resin, respectively. Specimens relined with autopolymerizing and light-cured resins were further classified into not-contaminated, water-contaminated and saliva-contaminated groups. Again, measurements of the transverse strength were taken for each group. The results were as follows 1. The transverse strength of heat-cured resin was superior to all the other resins. 2. The transverse strength of each specimen decreased after relining in the following order, heat-cured, visible light-cured, and autopolymerizing resin. 3. Surface contamination produced an decrease in transverse strength, especially in the saliva contaminated group. According to these results, water or saliva contamination should be avoided during intraoral relining procedures.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.291-297
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• 2011

Purpose: The purpose of this study was to know the availability of three photosensitizers, CQ, PD, DA, as a photosensitizer of dental resin composite. We want to know abortion band around visible light region for the using potential possibility as a photosensitizer for visible light cured dental composite resin. And I studied to know the relative photodecomposition ratio of three photosensitizers with or without photoinitiator, DAEM. Methods: The photodecomposition of three photosensitizers were studied by UV absorption spectroscopy in ethanol and determined by same instrument with irradiation time for relative photodecomposition. In order to study the effect of amine on photodecomposition was added the DAEM in the photosensitizer solution and the relative rate was measured by the same procedure with aove mentioned. Results: The all of three photosensitizers are absorbed around visible light region. The relative rate of decrease in absorbance incereased in the order: CQ < BD < PD. The effect of DAEM on the photodecomposition of the photosensitizers was appeared different results without DAEM. The photodecomposition rate of PD and DA decreased somewhat with the addition of amine, while that of CQ increased. The rtealtive photodecomposition rate increased in the oprder: BD ${\leq}$ CQ < PD with the addition of amine, but the differnce was not significant. Conclusion: PD and DA like CQ gives to the possibility of use as a photosensitizer for visible light cured dental composite resin by absorption around visible light region and photodecomposition in the maximum absorption wavelength. And it is showed that PD and DA are not effective decomposed with amine initiator, DAEM but CQ decomposed with DAEM effectively. This result may be due to a different mechanism operating for the decomposition of photosensitizers in the presence of amine.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.549-558
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• 1996

Light-cured orthodontic composite resin has been widely advertised recently for use in bonding brackets. However, the curability of light-cured resin when light waves are diffused through metal brackets in questionable. The purposes of this study were to evaluate shear bond strength and failure patterns of visible light-cured resin(Lightbond) and chemically cured-resin(Mono-Lok 2), and to determine the relative value of light-cured resin as an alternative to conventional chemically cured resin. Each of the two resins was tested on twenty extracted human first premolars. Standard edgewise metal brackets were bonded to the teeth in accordance with the manufacturers' recommendation. After bonding, the teeth were stored for 24 hours at $37^{\circ}C$, 100% humidity. The shear bond strength was tested with a universal testing machine(Instron 4302), at 0.5mm/min crosshead speed. After debonding, brackets and enamel surfaces were examined with a scanning electron microscope and a stereoscopic microscope. The results were as follows : 1. Metal brackets bonded with Lightbond showed statistically higher shear bond strength than metal brackets bonded with Mono-Lok2. 2. The predominant failure site in Lightbond was the enamel-resin interface, and in Mono-Lok 2 it was the resin itself. 3. Enamel cracks were not found in any specimen. The above results suggest that direct bonding of metal brackets to enamel with light-cured resin bonding agent can be used effectively in clinics.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.2
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• pp.327-346
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• 1996

The purpose of this study was to evaluate the shear bond strengths, microhardness, compressive strength and contraction gap at the resin-tooth interface of two types of composite resins polymerized with visible light and argon laser sourse. The results from the present study can be summarized as follows ; 1. Resin samples polymerized either by argon laser or visible light did not show significant difference in their physical properties tested(p>.05). 2. The contraction gap at the resin tooth interface was found to be present in all samples but any significant difference between groups could not be established due to their variability. Although the superiority of argon laser over visible light in enhancing the physical properties of resin could not be elucidated in the present study, continous efforts are deemed to be worthwhile to investigate this area using different conditions and materials of experiment.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.840-858
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• 1996

The main purpose of this study was to evaluate the anticariogenic effect of argon laser. Histological observations on lesion initiation and progression were performed under the polarized microscope. The results from the present study can be summarized as follows; 1. The specimens of laser cured group were shown to have more irregular and discontinuous lesion body in general than visible light cured group with rather continuous positive birefringence. 2. With lesion initiation and progression, almost all the specimens showed deeper body of lesion with shallower intact surface zone in the visible light cured group than the laser cured group(p<0.05). When the comparision was made between the two argon laser cured groups, the single-cure group showed deeper lesion body and the shallower surface layer than double-cure group. 3. Based upon the above mentioned results of this study, it can be assumed that the use of argon laser in the procedure of resin polymerization may provide the child and adolescent patient population with anticariogenic effect as well as efficient polymerization. Further studies using various materials and experimental conditions are being encouraged.

• Restorative Dentistry and Endodontics
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• v.25 no.1
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• pp.109-115
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• 2000

This study was designed to evaluate the microhardness of restorative composite resin and dual-cured composite resin cement which were light cured through the 1.5mm thickness composite overlay. For restorative materials, Z100 and Tetric Ceram were used. For dual cured composite cements, Variolink II((VL II) of three consistency (low, high, ultra high) were used. To determine the optimal microhardness of Z100, Tetric Ceram and Variolink II, each material was packed into the 1mm thickness teflon mold without composite overlay and light cured for 60 seconds. Then the microhardnesses of each sample were measured, averaged and regarded as optimal hardness of each material. To evaluate the microhardness of restorative composite resin and dual-cured composite resin cement which were light cured through the 1.5mm thickness composite overlay, the composites were packed into 1mm thickness teflon mold, coverd with celluloid strip, and then precured composite overlay which was made of Targis(Ivoclar/Vivadent, Liechtenstein) was positioned. 2 types of visible light curing machine, the power density of one of which was 400$mW/cm^2$ and the other was 900$mW/cm^2$, and one type of argon laser were used to cure the restorative composite and dual cured cement. For each group, 10 sample were assigned. The light curing tip was positioned over the composite overlay and light cured for 1min., 2min. or 3min with visible light curing machine or 15sec, 30 sec, 45sec, and 60 sec with argon laser. The Vickers hardnesses of upper and lower surface of Z100, Tetric Ceram, and 3 types of VL II cement were measured. When the 900 $mW/cm^2$ curing light was used, 2min. was needed for optimal curing of Z100 and Tetric Ceram. Variolink II did not be cured optimally even though the curing time was extended to 3min. When 400$mW/cm^2$ curing light was used, 3min. was necessary for Z100, whereas 3min. was not enough for Tetric Ceram. Variolink II was not cured optimally even though the curing time was extended to 3min. When argon laser was used, Z100, Tetric Ceram and Variolink II were not cured optimally in 60 seconds.

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.125-134
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• 1994

This study was designed for comparison of shear bond strengths and failure patterns of four experimental groups which combinated mesh-backed metal brackets and texture based ceramic brackets (Transcend series $2000^{(TM)}$) with chemically cured resin (Mono $Lok2^{(TM)}$) and visible light cured resin $(Transbond^{(TM)})$. Brackets were bonded on the extracted human bicuspids, after etching them by manufacturer's recommand, and the shear bond strengths were measured on the Instron machine after 24 hrs passed in the $37^{\circ}C$ water bath. The results were as follows. 1. Ceramic brackets, transcend series $2000^{(TM)}$, bonded with $MonoLok2^{(TM)}$ showed statistically higher shear bond strength than mesh-backed metal brackets bonded with $MonoLok2^{(TM)}$. 2. There was no significant difference in shear bond strengths between metal and ceramic brackets bonded with $(Transbond^{(TM)})$. 3. Ceramic brackets bonded with both $(Transbond^{(TM)})$) and $MonoLok2^{(TM)}$ showed primarily fractures between brackets adhesive interface. 4. Enamel crack was not found in anyone specimen.

• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.43-52
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• 1985

The purpose of this study was to measure the Micro-Knoop Hardness of three commercial visible light-cured composite resins (Plurafil-super, He1iosit and Durafi) according to the difference of depth and shade. Specimens of the resin were prepapared in plastic tubes 5mm in diameter with height of 5mm, and the tubes were put into the columned holes in stone molds. The molds were exposed to the visible light through the hole 5mm in diameter in metal plate. Specimens were sectioned (longitudinally) with disk. Knoop Hardness measurements were made at the depth of surface, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0mm from the surface to the deep portion. Knoop Hardness numbers were taken on each depth under 20gm load for 10 seconds with Shimadzu Tester. The following results were: 1. The highest hardness value was measured at 0.5mm depth. Then the deeper the depth, the lesser the hardness was observed. 2. The value of hardness was directly propotional to the time of exposure to the light. 3. The hardness of light shade resin was higher than the that of the dark shade. 4. The pattern of hardness change at varying depth is similar to all the experimental materials with no relation to the shade nor exposure time.

• Restorative Dentistry and Endodontics
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• v.18 no.1
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• pp.84-94
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• 1993

The purpose of this study was to evaluate flexure strength of composite resin inlay according to heat treatment and duration in comparasion with visible light-cured resin. In this study, materials were used 1 visible light-cured resin and 3 kinds of composite resin inlays. Control group was visible light cured resin (Photo Clearfil Posterior) and experimental groups were composite resin inlays (Brilliant Dentin, Brilliant Enamel and Clearfil CR Inlay). Experimental groups were divided 3 groups: First group was Brilliant Dentin and second group was Brilliant Enamel and -third group was Clearfil CR Inlay. Used experimental groups were calculated flexural strength according to heat treatment and duration. The following results were obtained: 1. Experimental groups were higher flexural strength than control group. 2. At $100^{\circ}C$ when heat treatment carried out 7 minutes flexural strength elevated third group, second group, first group in turn and when heat treatment carried out 15 minutes flexural strength elevated third group, second group, first group in turn but no difference was showed between first and second group. 3. At $125^{\circ}C$ when heat treatment was carried out 7 minutes flexural strength elevated third group, second group, first group in turn and when heat treatment was carried out 15 minutes flexural strength elevated third group, first group, second group in turn but no difference was showed between first and second group. 4. In spite of heat treatment and duration the third group was highest flexural strength in the others groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.62-75
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• 1998

The main purpose of this study was to compare the anticariogenecity of glass ionomer restorative material polymerized by argon laser versus visible light, The results from the present study can be summarized as follows; 1. Under the polarized light microscope, the specimens of laser-cured group showed the shallower lesion body than that of visible-light cured group, both in the stage of lesion initiation and progression. 2. Glass ionomer material cured by visible light showed shallower body of lesion than that of composite resin cured by argon laser at the stage of lesion progression(p<0.05). It was suggested fluoride released from the glass ionomer might have the additive anticariogenic effect. 3. Statistical difference between groups on depth of lesion body was evident after lesion progression (p<0.05). It was suggested that anticariogenic effect by argon laser was more effective at the stage of lesion progression than the lesion initiation. 4. The increment of lesion body during progression was highest in group IV (p<0.05). 5. Based upon the above-mentioned results of this study, it can be concluded that the advantage of anticariogenic effect and short curing time of argon laser in glass ionomer polymerization should be considered in children and adolescents whose caries activity is relatively higher.