• Restorative Dentistry and Endodontics
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• 제9권1호
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• pp.69-79
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• 1983

This study was undertaken to evaluate the effects of varnish application and thermocycling on the marginal leakage. 240 cavities of Class V were prepared on the 120 extracted premolars, and the cavities were filled with amalgam, Heliosit$^{(R)}$, and Hipol$^{(R)}$ after application of Copalite$^{(R)}$ or Duraphat$^{(R)}$. All specimens were immersed in methylene blue solution for 24 hours after thermocycling at $4^{\circ}C$ and $60^{\circ}C$, embedded in acrylic resin, and sectioned with low speed saw into two parts. The sectioned specimens observed with the metallurgical microscope. The following results were obtained: 1. The marginal seal was more effective in the amalgam-filled cavities after application of Copalite$^{(R)}$ threetimes or an application of Duraphat$^{(R)}$ varnish than in those without varnish applications. 2. Of the composite resin-filled cavities, the leakage of the varnish applied cases showed much more than without application. 3. There was no significant difference in the effect of marginal sealing between Copalite$^{(R)}$ and Duraphat$^{(R)}$ applications. 4. There was a significant difference in the degree of the marginal leakage of amalgam-filled cavities between the groups of thermocycling times, but no significant difference in the resin-filled cavities. 5. There was no significant difference in the degree of the marginal leakage between the Heliosit$^{(R)}$ and the Hipol$^{(R)}$ resin-filled cavities.

• Restorative Dentistry and Endodontics
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• 제13권1호
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• pp.69-78
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• 1988

The study was designed to establish a more nearly quantitative method for assessing the marginal leakage of dental restorations. 27 Class V cavities with $45^{\circ}$ bevel joint were prepared and classified into 2 groups. One group was filled with Scotchbond and silux. The other group was filled with glass ionomer cement, Scotchbond and silux. After finishing, all specimens were subjected manually to 100 thermal cycles at $0^{\circ}C$ and $100^{\circ}C$ water-bath. They were soaked in a samarium nitrate solution for 3 hours, irradiated with flux of $6{\times}10^{12}$ neutrons/$cm^2$/sec for 11 hours, cooled for 200 hours, counted with the HPGE detector and the tracer uptake was determined by comparison with a standard of samarium (10 ${\mu}g$). The following results were obtained. 1. Both of the two groups showed a considerable amounts of marginal leakage. 2. The group filled without glass ionomer cement base showed more marginal leakage than the group filled with glass ionomer cement base. 3. Neutron Activation Analysis produced a good quantitative method to measure the marginal leakage and samarium was appropriate to measure the marginal leakage of resin restorations using neutron activation analysis.

• Restorative Dentistry and Endodontics
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• 제13권1호
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• pp.79-89
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• 1988

The purpose of this study was to evaluate the canal preparation time, deviation of the apex (Zipping), and debridement effect of the canal of three canal preparation techniques. Thirty extracted 1st and 2nd molars were divided into 3 groups and each group was enlarged by ultrasonic, sonic or hand instrument. The specimens were examined under scanning electron microscope and light microscope. The results were as follows: 1. In the canal preparation time, ultrasonic group was the shortest, followed by sonic, hand group. All pairs of groups were significantly different at the 0.05 level. (P < 0.05) 2. In the deviation of the canal, no two groups were significantly different at the 0.05 level. (P > 0.05) 3. In the evaluation of debris scores, ultrasonic and sonic groups were better debridement effect than hand group in the fine canals. In the large canals, ultrasonic group was the best results, followed by sonic, hand group. 4. In the evaluation of smear layer scores, ultrasonic group was the best and sonic and hand group were same effect in the fine canals. In the large canals, three groups were same effect. 5. In the effect of the removal of predentin and pulpal debris, in the regardless of canal size, three groups were same and pulpal debris was not completely removed by either technique.

• Restorative Dentistry and Endodontics
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• 제11권1호
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• pp.89-95
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• 1985

The intact dental pulps which were free of their tooth bud from adult rat incisors, and oral mucosa were transplanted subcutaneously in homologous rats to study the formation of calcified tissue. The rat were sacrificed after 1,2,3 and 4 weeks following transplantation of dental pulp and oral mucosa. The samples which contained the transplanted and surrounding tissue were fixed in 10% NBF, stained with hematoxylin and eosin, alizarin red S, von Kossa, and alcian blue. Microscopic examinstins revealed as follows: 1. The transplanted oral mucosas were not calcified but tended to form the epithelial cysts. 2. At 1 week after transplantation of dental pulp the calcified structures were appeared at the periphery of the transplantation of dental pulp but weakly reacted to alizarin red S, von Kossa, and alcian blue. 3. At 2 weeks after transplantation of dental pulp the calcified structures began to expand from the periphery to the center of the transplanted dental pulp and occupied the large areas comparatively, and strongly reacted to alizarin red S, and von Kossa stains. 4. At 3 weeks after transplantation of pulp tissue the fibrous components were grown at the periphery of the transplanted pulp tissuesand at 4 weeks a large amount of fibrous tissues were observed. The transplanted pulp tissue tended to form foreign bodies gradually.

• Restorative Dentistry and Endodontics
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• 제11권1호
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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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• 제8권1호
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• pp.45-51
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• 1982

An endodontically treated tooth is likely to be brittle than a vital tooth. Internal structure of the tooth has been weakened due to a significant removal of dentin by coronal access, canal preparation. There are many controversies concerning with various methods of reinforcing an intact anterior tooth that has endodontic treatment. In this experiment, 128 extracted maxillary anterior teeth were endodontically treated, and prepared with 4 methods of restorations; Composite resin filling with zinc phosphate cement, composite resin filling without zinc phosphate cement, composite resin filling with post, and metal crown with post. An Instron testing machine was used to measure the fracture loads of the specimens. The means of the failure loads for the 4 groups were compared by F-test statistically and the failure modes were observed. The results were as follows; 1. There were no statistically significant difference between the failure loads of the four methods of restoration. 2. Teeth without post were fractured in a horizontal or oblique plane through upper or middle third of the root. 3. In the posted teeth, fractures were occurred around the post. 4. In the metal crowned teeth with post, the fracture were occurred around the post or coronal area.

• Restorative Dentistry and Endodontics
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• 제8권1호
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• pp.53-59
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• 1982

An in vitro study was performed in order to evaluate the restoring methods in the endodontically treated molar teeth. 68 extracted teeth were divided into 4 groups according to the restoring techniques. The teeth of first group were restored by amalgam. Those of second group were restored by the stainless steel post and amalgam. The teeth of the third group were restored by the amalgam with crown. The teeth of the fourth group were restored by the stainless steel post and amalgam core with crown. All the specimens were tested and measured for the fracture load by means of the Instron (UTM-111-500 Toyo Baldwin Co., LTD. Japan) and the Pressure Instrument (Yonsei University, Department of Metal Engineering.) The results were as follows; 1. There were no statistical differences in the fracture loads between the amalgam restoration and post-amalgam core restorative techniques. 2. The techniques of amalgam core with crown showed lower fracture loads those of post and amalgam core with crown. 3. In the crowned teeth, they presented higher fracture loads than those without crown.

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.145-152
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• 1984

The purpose of this study was to compare combinations of the four visible light irradiating appliances (Translux, Heliomat, Pluraflex HL 150, Omega) and the four visible light activated composite resins (Durafil, Heliosit, Plurafil-super, Silux) to determine the depth of polymerization of each combination. Twenty samples were made with Durafil. Five samples were polymerized for 20 seconds using Translux, five with Heliomat, five with Pluraflex HL 150, five with Omega. Twenty samples were made with Heliosit, twenty with Plurafil-super, and twenty samples with Silux. A 20-second polymerization time was applied with each of 4 visible light irradiating appliances to 5 samples of each material. Eighty samples were treated in a like manner, but polymerization was extended to 40 seconds. Depth of polymerization were measured with caliper. The results were as follows. 1) Of the two time exposures, 40-second exposure provided a significantly greater depth of polymerization than 20-second for each light with each material. 2) Durafill-Translux system showed minimum depth of polymerization, and Plurafil-Pluraflex system showed maximum depth of polymerization. 3) Visible light irradiating appliances were able to harden the resins cured by tire visible lights of other makers' apparatuses. 4) In all circumstances, depth of polymerization was between 3.0-3.8mm.

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.127-134
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• 1984

This study was conducted to evaluate the sealing ability of McSpadden technique compared with lateral condensation and Engine reamer technique, and according to the degree of canal enlargement and the use and nonuse of sealer. Seventy single-rooted teeth were divided into 14 groups and each tooth was enlarged and obturated according to the purpose of this study. Obturated teeth were infiltrated by Indian ink and decalcified and cleared. The apical sealing ability was evaluated by measuring the degree of ink penetration into the canal. The results were as follows: 1. All the teeth filled by lateral condensation using gutta-percha cone and sealer proved better in canal sealing ability than McSpadden technique and Engine reamer technique, showing less ink penetration. 2. In the McSpadden technique, there was less ink penetration detected in using the sealer than not. 3. In all of the experimental methods, the difference of the degree of ink penetration according the degree of canal enlargement could not be accepted. 4. There was no significant difference in ink penetration degree between Engine reamer technique using sealer and McSpadden technique without sealer.

• Restorative Dentistry and Endodontics
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• 제10권1호
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• pp.93-101
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• 1984

The experimental study was made to investigate the effect of the "Heliosit" composite resin on the dental pulp. The 36 class V cavities were prepared on the healthy permanent teeth of 3 days, and were divided into 5 groups and filled with the experimental filling materials. Control group: Zinc Oxide-Eugenol cement filling Experimental groups: Group 1: Dentin Adhesit application & Heliosit filling with or without dycal base Group 2: Heliosit filling with or without dycal base Group 3: Durafill filling with dycal base Group 4: Hipol filling with dycal base Animals were sacrificed after 1 weeks, 2 weeks, and 4 weeks following operation. The teeth were decalcified, sectioned and stained with hematoxylin and eosin. The results obtained form this study were as follows: 1. All experimental group showed slight pulp response. 2. Dentin Adhesit group showed minimal pulp response in both dycal bases and no base cases. 3. In group 2, mild pulp response was found in early stage and repairing process was found as the time elapsed. In no base cases, healing process was delayed slightly. 4. There was little difference in the result among Heliosit group, Durafill group and Hipol group.