• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.202-210
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• 2014

Purpose: The aim of this study was to evaluate the stress concentration and distribution whether restoring the cavity or not while restoring with metal ceramic crown on tooth with abfraction lesion using finite element analysis. Materials and methods: Maxillary first premolar was selected and made a total of 10 finite element model. Model 1 was natural tooth; Model 2 was tooth with metal ceramic crown restoration which margin was positioned above 2 mm from CEJ; Model 3 was tooth with metal ceramic crown restoration which margin was positioned on CEJ; Model 4 was natural tooth which has abfraction lesion; Model 5 and 6 had abfraction lesion and the other condition was same as model 2 and 3, respectively; Model 7 was natural tooth which had abfraction lesion restored with composite resin; Model 8 and 9 was tooth with metal ceramic crown after restoring on abfraction lesion with composite resin; Model 10 was restored tooth on abfraction lesion with composite resin and metal ceramic crown restoration which margin is positioned on lower border of abfraction lesion. Load A and Load B was also designed. Von Mises value was evaluated on each point. Results: Under load A or load B, on tooth with abfraction lesion, stress was concentrated on the apex of lesion. Under load A or load B, on tooth that abfraction lesion was restored with composite resin, the stress value was reduced on the apex. Conclusion: In case of abfraction lesion was restored with composite resin, the stress was concentrated on the apical border of restored cavity regardless of marginal position. It was favorable to place crown margin on the enamel for restoring with metal ceramic crown.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• The korean journal of orthodontics
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• v.20 no.3 s.32
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• pp.583-591
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• 1990

If the bond strength is sufficient to resist orthodontic force, orthodontic brackets can be bonded to restorations. Orthodontic brackets were bonded to composite resin and glass ionomer cement restorations with no-mix adhesive or glass ionomer cement. The shear bond strength of adhesives bonded to restorations was studied in vitro. Orthodontic brackets were bonded to 10 extracted natural teeth, 40 composite resin restorations and 40 glass ionomer restorations. The surfaces of composite resin restorations were roughened or applied with bonding agent (Scothbond) after surface roughening. The surfaces of glass ionomer cement restorations were conditioned with acid etching or applied with Scotchbond to etched surface. The adhesive was no-mix resin or glass ionomer cement. The shear bond strength was measured. The results were as follows: 1. Orthodontic brackets could be bonded to composite resin restorations effectively as they could be bonded to acid etched enamel with no-mix adhesive. The shear bond strength was sufficient to resist orthodontic force and was not affected by bonding agent greatly. 2. The shear bond strength of no-mix adhesive bonded to acid etched glass ionomer cement restorations was sufficient to resist orthodontic force. However. the fracture risk of glass ionomer cement restorations was increased during debonding. The bonding agent couldn't increase the shear bond strength greatly. 3. The shear bond strength of glass ionomer cement bonded to glass ionomer cement restorations was lower than that of no-mix adhesive. The shear bond strength was sufficient to resist orthodontic force and was greatly decreased by bonding agent. 4. The shear bond strength of glass ionomer cement bonded to composite resin restorations was too low to resist orthodontic force.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.106-115
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• 2010

The purpose of this study was to evaluate the microtensile bond strength (${\mu}TBS$), failure modes and bonding interfaces of self-etching and three self-adhesive resin cements to dentin and indirect composite resin. Cylindrical composite blocks (Tescera, Bisco Inc.) were luted with resin cements (PA: Panavia F 2.0, Kuraray Medical Inc., RE: RelyX Unicem Clicker, 3M ESPE., MA: Maxem, Kerr Co., BI: BisCem, Bisco Inc.) on the prepared occlusal dentin surfaces of 20 extracted molars. After storage in distilled water for 24 h, $1.0\;mm\;{\times}\;1.0\;mm$ composite-dentin beams were prepared. ${\mu}TBS$ was tested at a cross-head speed of 0.5 mm/min. Data were analyzed with one-way ANOVA and Tukey's HSD test. Dentin sides of all fractured specimens and interfaces of resin cements-dentin or resin cements-composite were examined at FESEM (Field Emission-Scanning Electron Microscope). In conclusion, PA and RE showed higher bond strength and closer adaptation than MA and BI when indirect composite blocks were luted to dentin using a self-etching and three self-adhesive resin cements.

• Journal of Technologic Dentistry
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• v.41 no.2
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• pp.87-92
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• 2019

Purpose: The Purpose of this study is to compare the fracture strength of 4 kinds of direct composite resins. Methods: his study performed experiments on the fracture strength of direct composite resins after polymerizing 4 kinds of direct composite resins on the MOD cavity standard specimens. Results: The fracture strength of Aelite(Bisco) was the highest at 176.26N(p<0.05). According to post-hoc study with Turkey honest significant difference by multiple comparison on fracture strength test results, there were statistically significant differences between all kinds of direct composite resin. But the statistical difference between Z350(3M) and Spectrum(DP) was not significant. Conclusion: Aelite(Bisco) scored the highest concerning the fracture strength.

• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.60-73
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• 1991

The purpose of this study is to evaluate the effects of etching time, environmental temperature and humidity on the adhesion of composite resin to glass-ionomer cement. Two chemical cure composite resins (Clearfil F II and Microrest AP) and two glass-ionomer cements (Fuji ionomer Type I and KET AC-CEM) were used as the experimental materials. The experiment is performed in 3 stages: The first stage is to bond composite resins to glass-ionomer cements, and the surface was not etched, and etched for 20 seconds, 40 seconds, and 60 seconds. Then specimens are stored in distilled water at $37^{\circ}C$ for 24 hours to measure tensile strength. The second stage is to choose the one group that had the highest tensile strength from the first stage and prepare two experimental groups: One group with composite resin bonded to glass-ionomer cement without etching and bonding agent application and the other with composite resin bonded to glass-ionomer cement with etching but without any bonding agent application. The specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and tensile strength is measured. The third stage is to choose group that had the highest tensile strength from the first stage experiment, and bond composite resin to glass-ionomer cement at $24^{\circ}C$ 44%, $30^{\circ}C$ 44%, $30^{\circ}C$ 80%, and $32^{\circ}C$ 92%. The storage time of specimens is to bond immediately after storage, then changed to 30 sec., 60 sec., and 120 sec.. Specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and their tensile strength are measured again. The following results were obtained: 1. As the etching time increases, the tensile bond strength between glass-ionomer cement and composite resin increase, and the tensile bond strength is the highest when acid etched for 60 minutes (P < 0.05). 2. After acid etching for 60 minutes, the tensile strength of the group with bonding agent was stronger than that without bonding agent application (P < 0.05). 3. The tensile strength of Clearfil F II was stronger than that of Microrest AP. 4. It was observed that the tensile bond strength is not affected by different storage time with different temperature and humidity. 5. As the humidity was increased, the tensile bond strength between glass-ionomer cement and composite resin decreased (P < 0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.133-149
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• 1998

Clinical application of composite resin recently draw great concerns in dentistry. Especially due to advantages such as esthetics, adhesiveness, simple clinical procedures, various shapes and kinds of composite resins are widely being applied to prosthodontics, conservative dentistry, and orthodontics. But, clinical problems attributable to the polymerization shrinkage of composite resin have been proposed, and we have to regard clinical problems such as secondary caries, loss of restoration, fracture of the surrounding tooth structure, marginal discoloration, and tooth sensitivity, and many portions are remained to be overcome. Therefore, this study attempts to analyze stress distribution between resin and tooth structure which is generated during polymerization shrinkage of composite resin using three dimensional finite element method. Three dimensional finite element models with conventional box-shape cavity and erosion/abrasion type V-shape lesion cavity in upper central incisor were developed. These cavities were filled with four different types of placement techniques. (bulk filling, horizontal increment filling, oblique occlusal increment filling, oblique gingival increment filling) The stresses generated by polymerization shrinkage of composite resin were calculated. The results analyzed with three dimensional finite element method were as follows : 1. The increment filling technique showed the highest maximum normal stress in both conventional box-shape and V-shape cavities and showed a tendency to decrease after complete polymerization. 2. The bulk filling technique resulted in increased stresses during the curing process in both conventional box-shape and V-shape cavities and the highest maximum normal stress occurred after complete polymerization. 3. The bulk filling resulted in the lowest maximum normal stress in both box-shape and V-shape cavities 4. Regardless of placement method, in conventional box-shape cavity, the maximum normal stress increased in dentin floor, enamel, dentin sequence and in V-shape cavity, the maximum normal stress increased in enamel, dentin sequence.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.1
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• pp.62-68
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• 1999

One of the many dilemmas that the clinical restorative dentist must face is treating young adolescent patient who prematurely loses his permanent teeth. Temporary prosthetic replacement can be achieved with removable denture, orthodontic band-wire fixed denture, adhesion bridge, composite resin splint with reinforcing material until the patients go through growth and development. But, all of these have limitations. Advances in restorative materials and reinforcement materials have made possible new techniques which are as much esthetic, conservative and more economic and stronger than adhesion brides. Two cases are being presented where gas-plasma treated, woven polyethylene fabric to reinforce composite resin was used to fabricate a temporary prosthetic restoration to replace a missing maxillary central incisor. This relatively noninvasive and basically reversible procedure allows the patient to decide the final restoration as he or she goes thorough maturation of the hard and soft tissues.

• The Journal of Korean Academy of Prosthodontics
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• v.26 no.1
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• pp.23-30
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• 1988

An in vitro study was performed to compare the retentive value of cast post cemented with three commonly used cements and one composite resin. Twenty cast posts were made from twenty extracted lower premolars. The samples were randomly divided into four groups. The first group was cemented with zinc phosphate cement, the second group with polycarboxylate cement, the third group with glass-ionomer cement, and the fourth group with composite resin. The tensile load test was performed on an Instron testing machine with crosshead speed of 2 mm/min and the results were compared statistically. The results were as follows ; 1. The mean value of tensile break force of cemented cast post was 23.36Kg in case of zinc phosphate cement, 16.28Kg in case of polycarboxylate cement, 22.09Kg in case of glass-ionomer cement , and 26.88Kg in case of composite resin. 2. Retention was not significantly different among zinc phosphate cement, glass-ionomer cement and composite resin. 3. Polycarboxylate cement was found to be less retentive than zinc phosphate cement, glass-ionomer cement , and composite resin.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.97-106
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• 1982

The purpose of this study was to evaluate the effect of different polishing procedures on the surfaces of composite resins. Two-paste type comosite restorative resin (Hipol) was selected for this study. 70 cavities prepared on the plaster-stone dies, 6mm in diameter and 2mm in depth, was filled with composite resin according to the manufacturer's specifications and by polymerizing against mylar strips. The polymerized composite resin specimens were polished (surface finished) by using 6 polishing devices; white stones, diamond finishing points, 12-fluted carbide finishing burs, green stones, sand paper disks, and Quasite rubber disk after polished with sand paper disks and green stones. A profilometer (Bendix type) was used to record in microinches the surface roughness of each surface finished composite resin specimens. The results were as follows. 1. The best finished surface that can be obtained is a surface formed by the mylar matrix strip 2. The white stones produced the smoothest surface in the experimental group. 3. The green stones produced the roughest surface in the experimental group. 4. It was proved that the gradual use of finishing instruments from a rough one to fine ones reduced the surface roughness.