• 구강회복응용과학지
• /
• 제23권4호
• /
• pp.269-281
• /
• 2007

Fluoric acid etching is an essential procedure in cementation of reinforced ceramics to tooth surface. But there have been few studies about the changes of surface structure and flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to the etching time. The objectives of this study were to examine the surface structure changes and the difference in biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic according to various etching times. Sixty one disk-shaped specimens of IPS $Empress^{(R)}$ 2 ceramic($14mm{\times}1.2mm$) were fabricated for the biaxial flexural strength test and SEM analysis according to the manufacturer's recommendations. Sixty specimens were divided into 6 groups(n=10) according to the time of HF acid etching(0, 20, 180 and 300s)and silane/resin cement application. Each disk was loaded using a piston-on-3 ball biaxial configuration in a universal testing machine. The failure loads(N) were recorded, and the biaxial flexural strength for each disk was calculated. A one-way analysis of variance and independent t-test on transformed fracture strength data were used to determine significant differences between groups. The groups of no cementation showed a trend toward progressive weakening with increasing the etching time. However, this was not statistically significant at p=0.05 level. The groups of resin cementation exhibited no apparent trend in their mean strength values. SEM photomicrographs showed very different results of etching. Within the conditions of this study, alteration of surface topography by acid etching does not have a deleterious effect on the biaxial flexural strength of IPS $Empress^{(R)}$ 2 ceramic.

• 대한치과보철학회지
• /
• 제38권5호
• /
• pp.606-617
• /
• 2000

The purpose of this study was to measure the marginal fidelities and the fracture strength of IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$ ceramic crowns. After constructed of 12 experimental dies for each group, ceramic crowns were fabricated on the metal master dies prepared on the maxillary right premolar Marginal gaps were measured on the specimen between the margin of each crown and finish-ing line of the metal master die by using stereo-microscope($SZ-ST^{(R)}$ Olympus, Japan) and all specimens were cemented on the metal master die with Bistite $II^{(R)}$ (Tokuyama soda Co, LTD., Japan) resin cement. Finally marginal gaps were measured again. To measure of the fracture strength, buccal incline on the functional cusp of specimens were loaded until the catastrophic failure occurred by using the AGS-1000 $D^{(R)}$(Shimadzu, Japan). The result of marginal fidelities and fracture strength were statistically analyzed with the SPSS version 8.0 programs. The results of this study were as follows : 1. No significant difference was found in the mean marginal fidelities and fracture strength between the IPS Empress $2^{(R)}\;and\;In-Ceram^{(R)}$. 2. In comparison of marginal fidelities between before and after cementation, there was significant difference(P<0.05). The IPS Empress 2 system was shown in this study that had good marginal fidelities and fracture strength compared to In-Ceram ceramics. Although this system was acceptable to clinical applications, the system still has to be considered long-term researches about marginal fidelities and fracture strength due to the lack of data about the clinical researches.

• 대한치과보철학회지
• /
• 제40권6호
• /
• pp.545-559
• /
• 2002

There has been increasing use of IPS Empress $2^{(R)}$ owing to easy fabrication method, high esthetics similar to natural teeth, good marginal accuracy, and sufficient fracture strength. However, in clinical application, although a luting agent and the tooth cementation bonding procedure influence the marginal accuracy and fracture strength restoration, there has been a controversy in the selection of proper luting agent. This study was to measure the marginal fidelites and fracture strength of IPS Empress crowns according to three cement types, Protec $cem^{(R)}$, Variolink $II^{(R)}$ and Panavia $21^{(R)}$. After construction of 12 experimental dies for each group, IPS Empress $2^{(R)}$ crowns were fabricated and luted the metal master die prepartion of the maxillary right premolar. Marginal gaps before cementation and after cementation were measured. Buccal incline on the functional cusp of specimens were loaded until the catastrophic failure and fracture strength was measured. The results of this study were as follows: 1. The range of gap was $34.04{\pm}4.84{\mu}m$ before cementation and $37.88{\pm}5.00{\mu}m$ after cementation, which showed significant difference by paired t-test (p<0.05). The difference in the results from marginal accuracy according to measuring point proved to be not statistically significant by two-way ANOVA test (p>0.05). 2. The difference in the results from marginal accuracy according to three cement types Proved that The Variolink $II^{(R)}$ cement group had the least gap, $35.43{\pm}5.03{\mu}m$, and showed superior marginal accuracy while there existed statistic significance in Protec $cem^{(R)}$ cement group, $39.06{\pm}4.41{\mu}m$ or Panavia $21^{(R)}$ cement group, $39.16{\pm}4.39{\mu}m$ by two-way ANOVA test & multiple range test (p<0.05). 3. The difference in the results from fractures strength testing according to three cement type groups proved to be statistically significant (p<0.05). The Variolink $II^{(R)}$ cement group shows highest fracture strength of $1257.33{\pm}226.77N$, Panavia $21^{(R)}$ cement group has $1098.08{\pm}138.45N$, and Protec $cem^{(R)}$ cement group represents the lowest fracture strength of $926.75{\pm}115.75N$. 4. Three different cement groups of different components showed acceptable marginal fidelity and fracture strength. It is concluded that IPS Empress $2^{(R)}$ crowns luted using Variolink $II^{(R)}$ cement group had stronger fracture strength and smaller marginal gap than the other cement groups. Although Variolink $II^{(R)}$ resin cement seemed acceptable to clinical applications in IPS Empress $2^{(R)}$ system, the IPS Empress $2^{(R)}$ system still requires long-term research due to the lack of data in clinical applications.

• 대한치과보철학회지
• /
• 제39권5호
• /
• pp.477-491
• /
• 2001

The purpose of this study is to compare and analyze the shade changes(${\Delta}E^*$) about $In-Ceram^{(R)}$, $IPS-Empress^{(R)}$, $OPC^{(R)}$ by using of the spectrophotometer arising from inital status and before and after cementation of the resin cement mounted on the metal core. We used a couple of statistics such as 'One- Way ANOVA' and 'Multiple Range Test.' We could be able to verify significantly what is being discussed here up to 95%. The results drawn from our research are as follows : 1. At the time of our experiments regarding the initial shapes of all-ceramic and mounting status of all-ceramic on the metal crown(${\Delta}E^*1$), and a comparison of mounting of all ceramic on the metal crown with all-ceramic cemented on the metal core(${\Delta}E^*2$), at the time of shade change of initial shapes and after we cemented on the metal core. (1) no significant difference among all-ceramics was found. (2) no particular difference was found regarding the $In-Ceram^{(R)}$. (3) a significant difference between the ${\Delta}E^*1$ and ${\Delta}E^*2$ regarding the $IPS-Empress^{(R)}$ was found(P<0.05). (4) a significant difference between the ${\Delta}E^*1$ and ${\Delta}E^*2$ regarding the $OPC^{(R)}$ was found(P<0.05). 2. When we compared the shade changes(${\Delta}E^*$) resulted from before and after the cementation on each of the parts involved of some all-ceramic, we could be able to find shade change increase form incisal third, middle third. and cervical third in that order in $In-Ceram^{(R)}$(spinell), IPS $Empress^{(R)}$, and $OPC^{(R)}$ all. In addition. we could be able to find a significant difference between cervical third and incisal third, middle third. (P<0.05) From what we have just seen, we might conclude that there is a significant shade change difference before and after the cementation with respect to $IPS-Empress^{(R)}$ and $OPC^{(R)}$. In addition, we could also be able to find more shade change difference at the cervical third rather than incisal third and middle third depending on the parts involved.

• 대한치과보철학회지
• /
• 제40권4호
• /
• pp.365-373
• /
• 2002

The purpose of this study was to investigate the effects of desensitizer on shear bond strength of adhesive resin cements for all ceramic crown. For this study, Gluma $desensitizer^{(R)}$(Heraeus Kulzer, Germany) and MS $Coat^{(R)}$(Sun medical, Japan) were used as desensitizer, and Bistite $II^{(R)}$ resin cement(Tokuyama, Japan) and Variolink $II^{(R)}$ resin cement (Ivoclar, Liechtenstein) were used. IPS Empress ceramics were bonded to dentin surfaces after application of desensitizer and shear bond strength of specimens were measured using UTM(Zwick 1456 41. Zwick, Germany) at a crosshead speed of 1mm/min. The obtained results were as follows : 1. The shear bond strength of both resin cements were not affected by Gluma $desensitizer^{(R)}$ containing HEMA 2. The shear bond strength of Bistite $II^{(R)}$ resin cement was significantly decreased by MS $Coat^{(R)}$. 3. The failure mode in MS $Coat^{(R)}-Bistite \;II^{(R)}$ group was mainly adhesive type between dentin and resin cement. but that of Gluma $desensitizer^{(R)}$-Variolink $II^{(R)}$ group was mainly mixed type, combined adhesive failures between dentin and resin cement or porcelain and resin cement.

• 대한치과보철학회지
• /
• 제40권5호
• /
• pp.493-506
• /
• 2002

Recently as the esthetic concerns about dental prosthesis have been increased, the nonmetallic post and core systems have been introduced clinically to improve the color and the low optical transmittance of conventional casting metal post and core systems. The purpose of this study was to compare and analyze the optical transmittance and the shade changes of all-ceramic crowns with two nonmetallic post and core systems. The experimental groups were classified as follows : Total 27 specimens(9 samples in each group) were evaluated. Group I : Natural teeth as a control group Group II : CosmoPost and $Empress^{(R)}$ core (Ivoclar-Vivadent, Liechtenstein) Group III : $LIGHT-POST^{TM}$ and $LIGHT-CORE^{TM}$ (Bisco, U.S.A.) In all group, all-ceramic crowns were fabricated with the same shade of IPS $Empress^{(R)}$ II (Ivoclar-Vivadent, Liechtenstein) after abutment preparation, and then two kinds of spectrophotometers, UV 3101 PC (Shimadzu, Japan) and CM 503i (Minolta Co. Ltd. Japan), were used to measure the optical transmittance and the color value. The following results were obtained : 1. The optical transmittance of each group without all-ceramic crowns, was siginificantly decreased in order of Group III, I and II (p<0.05). 2. The optical transmittance of each group with all-ceramic crowns cemented, were siginificantly decreased in order of Group I, II and III (p<0.05). 3. In comparison with the shade of all-ceramic crowns, there were no significant differences between groups regardless of the cementation. 4. In comparison with the shade changes in each group after the cementation of all-ceramic crowns, there were no significant differences between groups. From the above results, it is thought that the selection among materials used in this study doesn't influence greatly the esthetic restoration, because the differences of optical transmittance were so small that those were clinically insignificant.