• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.79-86
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• 2008

The purpose of this study was to investigate the effect retention element formed by metal surface treatment method on the bond strength of indirect composite resin and metal. The metal specimens were cast from Ni-Cr alloy($Rexillium^{(R)}$ III). They were divided into 5 groups by applied retention element: $50{\mu}m$ aluminium oxide sandblasting group, $250{\mu}m$ aluminium oxide sandblasting group, 0.2mm retention crystal group, 10% $H_{2}SO_{4}$ solution etching group, $110{\mu}m$ $Rocatec^{TM}$ Plus system group. Total 50 metal specimens were veneered with Sinfony indirect composite resin system. Specimens were tested for shear bond strength on an Instron universal testing machine and fracture mode of fractured specimens were analyzed by SEM and EDS. 1. 0.2 mm retention crystals were most effective in improving the resin-metal shear bond strength (p<0.05). 2. Sandblasting by $250{\mu}m$ aluminium oxide were more effective than sandblasting by $50{\mu}m$ aluminium oxide in improving the resin-metal shear bond strength(p<0.05). 3. Fracture mode of resin-metal fractured surface were cohesive failure mode in 0.2mm retention crystal, mixed failure mode in sandblasted specimens, etched specimens and the specimens sandblasted with $110{\mu}m$ $Rocatec^{TM}$ Plus system.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.219-248
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• 1989

The purposes of this study were to analyze the microstructural and compositional changes of metal surfaces following different conditions of preoxidizing heat treatment, to investigate the composition of metal oxides, and to evaluate the effect of preoxidation and removal of surface oxides on microstructure and diffusion profiles. The techniques of EDAX (energy-dispersive analysis of x-ray), ESCA (electron spectroscopy for chemical analysis), and EPMA (electron probe micro analysis) were used, along with SEM (scanning electron microscopy). The obtained results were as follows : 1. A surface of the specimen became rough and the amount of the metal oxides increased with increasing the heat treatment time and temperature and the partial pressure of oxygen. 2. At an air pressure of 28' vacuum, the higher the temperature and the longer the time of preoxidation, the higher Ni concentration was detected. 3. Cr concentration in the specimen heat treated with air was higher than that of with vacuum. 4. The oxides in the specimens were mainly composed of Ni and Cr oxides. On the globular growth particles, significant rises in Al concentration of Rexillium III and Ti concentration of Verabond were noted. 5. Atomic diffusion occurred at the ceramic-metal interface, furthermore the amount of the flux was increased with preoxidation heat treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.295-302
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• 2007

Statement of problem. Fracture of the tooth-colored superstructure material is one of the main prosthetic complications in implant-supported prostheses. Purpose. The purpose of this in vitro study was to compare the fracture strength between the cement-retained implant-supported metal-ceramic crowns and the indirect composite resinveneered metal crowns under the vertical compressive load. Material and methods. Standard implants of external type (AVANA IFR 415 Pre-mount; Osstem Co., Busan, Korea) were embedded in stainless steel blocks perpendicular to their long axis. Customized abutments were fabricated using plastic UCLA abutments (Esthetic plastic cylinder; Osstem Co., Busan, Korea). Thirty standardized copings were cast with non-precious metal (Rexillium III, Pentron, Walling ford, Conn., USA). Copings were divided into two groups of 15 specimens each (n = 15). For Group I specimens, metal-ceramic crowns were fabricated. For Group II specimens, composite resin-veneered (Sinfony, 3M-ESPE, St. Paul, MN, USA) metal crowns (Sinfony-veneered crowns) were fabricated according to manufacturer's instructions. All crowns were temporary cemented and vertically loaded with an Instron universal testing machine (Instron 3366, Instron Corp., Norwood, MA, USA). The maximum load value (N) at the moment of complete failure was recorded and all data were statistically analyzed by independent sample t-test at the significance level of 0.05. The modes of failure were also investigated with visual analysis. Results. The fracture strength of Sinfony-veneered crowns ($2292.7{\pm}576.0N$) was significantly greater than that of metal-ceramic crowns ($1150.6{\pm}268.2N$) (P < 0.05). With regard to the failure mode, Sinfony-veneered crowns exhibited adhesive failure, while metal-ceramic crowns tended to fracture in a manner that resulted in combined failure. Conclusion. Sinfony-veneered crowns demonstrated a significantly higher fracture strength than that of metal-ceramic crowns in cement-retained implant-supported prostheses.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.5
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• pp.620-639
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• 1999

Indirect composite resins are used as an popular effective esthetic material in prosthetic dentistry, often with metallic substructure that provides support for restorations. Recently, new indirect composite resins as a substitute of ceramic have been developed. These resins provide good esthetics, with a wide range of hue and chroma. And the flexural strength of those is in the range of 120-150MPa, Which is higher than that of feldspathic Ceramic, and similar th that of Dicor. Although it has many merits, one of the major clinical problems of composite resins is the bond failure between metal and resin due to insufficient interfacial bond strength. The purpose of this study was to evaluate shear bond strength of the reinforced indirect composite resin to dental alloys. Three different composite resin systems($Artglass^{(R)},\;Sculpture^{(R)},\;Targis^{(R)}$) as test groups and ceramic($VMK\;68^{(R)}$) as control group were bonded to Ni-Cr-Be alloy($Rexillium\;III^{(R)}$) and gold alloy(Deva 4). All specimens were stored at $^37{\circ}C$ distilled water for 24 hours and the half of specimens were thermocycled 2000 times at temperature from $5^{\circ}C\;to\;60^{\circ}C$. The shear bond strengths of reinforced indirect composite resins to dental alloys were measured by using the universal testing machine, and modes of debonding were observed by stereoscope and scanning electron microscope. The results were as follows: 1 The shear bond strengths of reinforced indirect composite resins to dental alloys were approximately half those of ceramic to dental alloys(P<0.01). 2. There was no significant difference between the shear bond strength of several reinforced indirect composite resins to metal. 3. Alloy type did not affect on the shear bond strengths of resin to metal, but the shear bond strengths of ceramic to gold alloys were higher than those of ceramic to Ni-Cr alloys(P<0.05). 4. The shear bond strengths of Artglass and Targil to gold alloys were significantly decreased after thermocycling treatment(P<0.01). 5. Sculpture showed cohesive, adhesive, and mixed failure modes, but Artglass and Targis showed adhesive or mixed failures. And ceramic showed cohesive and mixed failures.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.53-76
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• 1990

The purpose of this study was to evaluate the tensile bond strength of adhesive resins to successively recast Rexillium III and Degudent-U. Recasting was done 4times successively. Specimen $A_1$, were cast by new metal, and $A_2$ by surpus of $A_1$, $A_3$ by surplus of, $A_2$ $A_4$ by surplus of $A_3$, $A_5$ by surplus of $A_4$ plus 50% new metal. The types of surface treatment for resinbonded restoration in this experiment were electrolytic etching by OXY-ETCH(Oxy dental products, Inc., Hillside, New Jersey, U.S,A.), aluminum oxide blasting, anodic oxidation by EZ-OXISOR( Towagiken Co., Kyoto, Japan), electrotinplating by Kura Ace(Kuralay Co., Kyoto, Japan). Three kinds of cementing resin used in this study were Comspan(K.P. Cauil Co, Milford Delaware, U.S.A.), Super Bond C&B(Sun-Medical Co. Ltd., Kyoto,Japan), Panavia EX(Kuralay Co., Ltd., Osaka, Japan). Tensile bond strength was measured by Instron Universal testing machineModel 1125) and all the specimen were observed with SEM(JEOL, JSM-T2000) and mode of bond failure were recorded. The obtained results were as follows : 1. In electrolytic etched group, tensile bond strength was decreassed when recast alloy was used, and tensile bond strength of Compan and panavia EX were not significantly different(P>0.05). 2. In remaining group treated by aluminum oxide blasting, EZ-OXIOR, Kura Ace, tensile bond strength were not changed when recast alloy were used, and tensile bond strength of SuperBond(C&B and Panavia EX were not significantly different(P>0.05). 3. IN SEM evaluation, electrolytic etched group and electrotinplated group exhibited different image when recast alloy was used, and remaining groups treated by aluminum oxide blasting, EZ-OXISOR exhibited the same. 4. IN observation of bond failure, electrolytic etched group exhibited adhesive failure and remaing groups treated by aluminium oxid blasting, EZ-OXISOR, Kura Ace exhibited adhesive and cohesive failure.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.2
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• pp.165-173
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• 2006

Purpose: With gold electroforming system fir the double crown, the secondary crown is electroformed directly onto the primary crown. An even thick layer of high precision can be acquired. It is thought that the retention of electroformed outer crown is primarily acquired by the adhesive force (surface tension) through the saliva which is interposed between precisely fitted inner and outer crown. The purpose of this study was to investigate the effect of taper and surface area of inner crown on the retentive force of electroformed outer crown according to the presence of saliva. Materials and methods: 32 titanium inner crowns with cervical diameter of 8 mm and cone angles of 0, 2, 4, 6 degrees, which had same surface area by regulated height, were machined on a lathe. Another 32 titanium inner crowns with cone angles of 0, 2, 4, 6 degrees, which had doubled surface area by increased cervical diameter. were fabricated. Eight specimens of each group, for a total of 64 titanium inner crowns, were prepared. The electroformed outer crowns were fabricated directly on the inner crowns by using electroforming machine(GAMMAT free, Gramm Technik, Germany). The tertiary frameworks were waxed-up on the electroformed outer crown and cast using nonprecious alloy($Rexillium^(R)III,\;Jeneric^(R)/Pentronh^(R)$ Inc., USA). The cast metal frameworks were sandblasted with alubimium oxides and cemented using resin cement(Superbond C&B, Sun Medical Co., Japan) over the electroformed copings of each specimen. Then, artificial saliva($Taliva^(R)$, Halim Pharm. Co., Korea) was sprayed between the inner and outer crown, and they were connected under 5 kg force. The retentive force was measured by the universal testing machine(Tinius Olsen 1000, Tinius Olsen, USA) with a cross-head speed of 66.67 mm/sec. The direction of cross-head travel was exactly aligned with the path of removal of the respective specimens. This measurement procedures for retentive force of electroformed outer crown with artificial saliva were repeated in the same way without presence of artificial saliva. Results and Conclusion: The following conclusions were drawn: 1. The retentive force of electroformed outer crown was decreased according to increased taper of inner crown(P<.05). 2. The retentive force of electroformed outer crown showed no significant differences according to surface area and the presence of artificial saliva(P>.05).

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.92-98
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• 2012

Purpose: The aim of this study was to evaluate the effects of different abutment materials on abutment screw loosening and settling-down effect in conical connection type implant system. Materials and methods: Three types of abutment, cementation, gold UCLA, and metal UCLA abutment were used. Two UCLA groups were fabricated in a similar pattern to cementation abutment. Type III gold alloy and Nickel-Chromium alloy was used for casting gold UCLA abutment and metal UCLA abutment, respectively. Fixture and abutment were tightened to 30 Ncm by using digital torque controller and re-tightening was conducted with same force after 10 minutes. Digital torque gauge was used to measure loosening torque and fixture/abutment length was measured by digital micrometer. Dynamic loads between 25 N and 250 N were applied with $0^{\circ}$ angle to the abutment axis. After loading, fixture/abutment length was re-measured and amount of settlement was calculated. Loosening torque value was also measured for comparison Results: All three groups showed significant differences of length when comparing before and after loading, but there was no significant difference of settling amount in all groups. Loosening torque values were significantly decreased when comparing before and after loading in all groups($P$<.05). However, there was no significant difference in loss of loosening torque values when compared to groups. Conclusion: In internal conical connection type implants, dynamic load affected on settlement and loosening torque of implant, but there was no differences between abutments materials. Likewise gold UCLA abutment, metal UCLA abutment might be able to withstand functional load.