In this study we evaluated the influence of both the thickness of residual enamel and the color of the composite resins applied to lingual surface on the labial surface color.

Background plates were made by randomly (A1, A2, A6D, B1, B2, B3, C1, C2, C6D) selected colors of Filtek Supreme (3M ESPE, St. Paul, U.S.A.) composite resin.

Crown portion of 9 maxillary central incisors were cut off and embedded with acrylic resin except labial surface. Samples of average thickness of 2.2 mm were obtained after cutting it in a thickness of 2.5 mm from the labial surface and sandpaper polish.

The shade of composite resin background was measured using Spectrophotometer (Spectrolino® GretagMacbeth, Regensdorf, Switzerland). And CIE L^*a^*b^* value of 2.2 mm thickness tooth samples were measured on the 9 composite resin backgrounds. And then, the cutting side of tooth samples was ground to the extent of 1.9 mm, 1.6 mm, 1.3 mm, 1.0 mm and placed on composite resin backgrounds and measured L^*a^*b^* values with the same method.

In all samples, L^* value and b^* value seemed to have a tendency of decreasing as thickness of tooth sample becomes thinner regardless of background colors (p < 0.05). But, a^* value didn't show the significant differences depending on the thickness.

The objective of this study was to evaluate the effect of color measuring instrument by measuring the color of dental composite resins.

Nine shade light cured composite resin disks were prepared (diameter : 15 mm, thickness : 4 mm). CIE L^*a^*b^* color scale of each disk was measured with 3 different types of spectrophotometer [MiniScan XE plus (Model 4000S, Hunter Lab, USA), CM-3500d (Minolta, Japan) and Specbos 2100 Miniature VIS Reflection spectrometer (Serial No: 319416, JETI Technishe VIS Instrumentic GmbH, Germany)]. Miniscan XE Plus and CM-3500d using identical measuring geometry with different size of viewing aperture. But Specbos 2100 using different measuring geometry.

Within the limitation of this study, there were color difference (ΔE^*) from 2.4 to 7.8 between Miniscan XE Plus and CM-3500d, but L^*, a^*, b^* values showed the high correlation. However, there were great color difference (ΔE^*) in the extent of about 20 between instruments with the different measuring geometry.

Therefore, color scale measured by color measuring instrument should be used as a relative value rather than an absolute value in the field of dentistry.

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement.

Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration: Variolink-II (Ivoclar-Vivadent): Exite DSC, Panavia-F (Kuraray): ED-Primer, RelyX Unicem (3M ESPE): Single-Bond, Duolink (Bisco): One-step, Mulitlink (Ivoclar-Vivadent): Multilinh Primer.

Shear bond strength was measured by Instron universal testing machine.

Adhesive application improved shear bond strength (p < 0.05). But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application.

With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.

This study was done to evaluate the reliability of the digital color analysis system (ShadeScan, CYNOVAD, Montreal, Canada) for dentistry.

Sixteen tooth models were made by injecting the A2 shade chemical cured resin for temporary crown into the impression acquired from 16 adults. Surfaces of the model teeth were polished with resin polishing cloth. The window of the ShadeScan handpiece was placed on the labial surface of tooth and tooth images were captured, and each tooth shade was analyzed with the ShadeScan software. Captured images were selected in groups, and compared one another.

Two models were selected to evaluate repeatability of ShadeScan, and shade analysis was performed 10 times for each tooth.

And, to ascertain the color difference of same shade code analyzed by ShadeScan, CIE L^*a^*b^*values of shade guide of Gradia Direct (GC, Tokyo, Japan) were measured on the white and black background using the Spectrolino (GretagMacbeth, USA), and Shade map of each shade guide was captured using the ShadeScan.

There were no teeth that were analyzed as A2 shade and unique shade. And shade mapping analyses of the same tooth revealed similar shade and distribution except incisal third.

Color difference (ΔE^*) among the Shade map which analyzed as same shade by ShadeScan were above 3.

Within the limits of this study, digital color analysis instrument for dentistry has relatively high repeatability, but has controversial in accuracy.

The purpose of this study was to evaluate the insertion depth of several brands of master gutta percha cones after shaping by various Ni-Ti rotary files in simulated canals.

Fifty resin simulated J-shape canals were instrumented with ProFile, ProTaper and HEROShaper. Simulated canals were prepared with ProFile .04 taper #25 (n = 10), .06 taper #25 (n = 10), ProTaper F2 (n = 10), HEROShaper .04 taper #25 (n = 10) and .06 taper #25 (n = 10). Size #25 gutta percha cones with a .04 & .06 taper from three different brands were used: DiaDent; META; Sure-endo. The gutta percha cones were selected and inserted into the prepared simulated canals. The distance from the apex of the prepared canal to the gutta percha cone tip was measured by image analysis program.

Within limited data of this study, the results were as follows

1. When the simulated root canals were prepared with HEROShaper, gutta-percha cones were closely adapted to the root canal.

2. All brands of gutta percha cones fail to go to the prepared length in canal which was instrumented with ProFile, the cones extend beyond the prepared length in canal which was prepared with ProTaper.

3. In canal which was instrumented with HEROShaper .04 taper #25, Sure-endo .04 taper master gutta percha cone was well fitted (p < 0.05).

4. In canal which was instrumented with HEROShaper .06 taper #25, META .06 taper master gutta percha cone was well fitted (p < 0.05).

As a result, we concluded that the insertion depth of all brands of master gutta percha cone do not match the rotary instrument, even though it was prepared by crown-down technique, as recommended by the manufacturer. Therefore, the master cone should be carefully selected to match the depth of the prepared canal for adequate obturation.

The most scientific and reliable method for deciding the tooth color is the instrumental measurement. However, such color measuring instrument shows the difference of the measuring value according to the diversified measuring condition.

This study was conducted to evaluate what effect of the labial surface irregularity of the tooth to the result of the color measured by spectrometer.

11 models of the teeth were made by injecting the A2 shade Luxatemp Automix Plus (DMG, Germany) into the impression acquired from 11 adults. Standard disk samples (15 mm diameter, 7 mm thickness) were made with same material. CIE L^*a^*b^* value was measured at the incisal, central, and gingival area of the central incisor, lateral incisor, canine and first premolar using Specbos 2100 (JETI, Germany) spectrometer. Color difference was calculated between labial surface and standard samples.

Among all models of the teeth, L^* and b^* value showed the reducing tendency as they go toward the gingival area, but a^* value showed the increasing tendency.

Color difference between model teeth and standard samples showed the most difference at the incisal area, but the gingival area showed the least difference. And the canine showed the least color difference from the comparison of standard sample, and the central incisor showed the highest difference (p < 0.01).

Although the visually detectable difference of the measuring value showed notably depending on the type and measured area (p < 0.05), L^* and a^* value showed notable differences depending more on the measured areas than on the type of the teeth.

The purpose of this study is to develope new dental color-space system. Twelve kinds of dental composites and one kind of dental porcelain were used in this study. Disk samples (15 mm in diameter, 4 mm in thickness) of used materials were made and sample's CIE L^*a^*b^* value was measured by Spectrocolorimeter (MiniScan XE plus, Model 4000S, diffuse/8° viewing mode, 14.3 mm Port diameters, Hunter Lab. USA). The range of measured color distribution was analyzed. All the data were applied in the form of T### which is expression unit in CNU Cons Dental Color Chart.

The value of L^* lies between 80.40 and 52.70. The value of a^* are between 10.60 and 3.60 and b^* are between 28.40 and 2.21. The average value of L^* is 67.40, and median value is 67.30. The value of a^* are 2.89 and 2.91 respectively. And for the b^*, 14.30 and 13.90 were obtained. The data were converted to T### that is the unit count system in CNU-Cons Dental Color Chart. The value of L^* is converted in the first digit of the numbering system. Each unit is 2.0 measured values. The second digit is the value of a^* and is converted new number by 1.0 measured value. For the third digit b^* is replaced and it is 2.0 measured unit apart. T555 was set to the value of L^* ranging from 66.0 to 68.0, value of a^* ranging from 3 to 4 and b^* value ranging from 14 to 16.

The objectives of this study were to evaluate the effect of surface roughness on the surface color and translucency of the composite resins.

Two composite resins (Esthet-X, Dentsply, Milford, USA and Charisma, Kulzer, Domagen, Germany) were used to investigate the surface color. Charisma was used to investigate the translucency. 40 disc samples (diameter: 8 mm, thickness: 5 mm) were made by each product to measure the surface color. Polymerized each sample's one side was treated by Sof-Lex finishing and polishing system (Group C, M, F, SF). 40 disc samples (diameter: 6 mm, thickness: 1 mm) were prepared to measure the opacity. 1 mm samples were ground one side with #600, #1000, #1500 and #2000 sandpapers. CIE L*a*b* values of each 5 mm thickness samples, and XYZ values of 1 mm thickness samples on the white and black background were measured with spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland).

Mean surface roughness (Ra) of all samples before and after surface treatment was measured using the Surface Roughness Tester SJ-301 (Mytutoyo, Tokyo, Japan).

Regardless of type and shade of the composite resin, L* values measured in group C were higher than others (p < 0.05), and L* value decreased as the Ra value decreased except B3 shade of Esthet-X. But there were no significant difference in a* values among groups. In control group and SF, highest b* values were measured (p < 0.05), except B1 shade of Esthet-X.

Contrast ratio decreased as the Ra value decreased (p < 0.05).

With the above results, difference of surface roughness has influence on surface color and translucency of dental composite resins.