The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts.

Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany)

The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of 10 × 10 pixel and compared in mm Al equivalent at five points.

Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken.

We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area.

The following results were obtained.

Each post system showed various radiopacity.

Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.

This study was performed to assess the radiopacity of a variety of root canal sealers according to the specification concerning root canal sealers.

Ten materials including Tubli-Seal™, Kerr Pulp Canal Sealer™, AH 26®, AH plus®, AH plus jet™, Ad sea l™, Sealapex™, NOGENOL™, ZOB seal™, Epiphany™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film was performed at different voltage and exposure time. In the second part, ten specimens were radiographed simultaneously with an aluminum step wedges on the occlusal films under decided condition. The mean radiographic den sity values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

1. Among the various conditions, the appropriate voltage and exposure time that meet the requirement density was 60 kVp at 0.2 s

2. All of the materials had greater radiopacity than 3 mm Al requirement of ANSI/ADA specification No. 57 (2000) and ISO No. 6876 (2001) standards.

3. The radiopacity of materials increased as thickness of materials increased.

4. The mm Al value of each specimen at 1mm in thickness has a significant difference in the statistics.

It suggests that root canal sealers have a sufficient radiopacity that meet the requirement.

This study was performed to assess the radiopacity of a variety of canal filling and retrograde root-end filling materials according to the specification concerning root canal obturation materials.

Ten materials including Gutta-percha pellets, amalgam, Fuji II LC, Dyract® AP, Super EBA®, IRM®, AH 26®, Sealapex™, Tubli-Seal™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film were performed at 60 kVp (0.2, 0.3, 0.4 s), 70 kVp (0.2, 0.3, 0.33 s) to decide appropriate voltage and exposure time. In the second part, ten specimens which are 5 mm in diameter and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm in thickness, were fabricated from each material studied. The specimens were radiographed simultaneously with an aluminum step wedge under decided condition (60 kVp, 0.2 s). The mean radiographic density values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

Among the various conditions including 0.2 s, 0.3 s, 0.4 s at 60 kVp and 0.2 s, 0.3 s, 0.33 s at 70 kVp, the appropriate voltage and exposure time that meet the requirement of density from 0.5 to 2.0 was 0.2 s at 60 kVp.

It suggests that all experimental canal filling and retrograde root-end filling materials have a sufficient radiopacity that meet the requirement concerning root canal obturation materials except for Fuji II LC and Dyract.

The aim of this study was to evaluate the radiopacity and cytotoxicity of three resin-based (AH 26, EZ fill and AD Seal), a zinc oxide-eugenol-based (ZOB Seal), and a calcium hydroxide-based (Sealapex) root canal sealers. Specimens, 10 mm in diameter and 1 mm in thickness, were radiographed simultaneously with an aluminum step wedge using occlusal films, according to ISO 6876/2001 standards. Radiographs were digitized, and the radiopacity of sealers was compared to the different thicknesses of the aluminum step wedge, using the Scion image software. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the cytotoxicity of each material was determined in immortalized human periodontal ligament (IPDL) cells.

The results demonstrated that EZ fill was the most radiopaque sealer, while Sealapex was the least radiopaque (p < 0.05). AH 26, AD Seal and ZOB Seal presented intermediate radiopacity values. All the materials evaluated, except for Sealapex, presented the minimum radiopacity required by ISO standards. The cell viabilities of resin-based root canal sealers were statistically higher than that of other type of root canal sealers through the all experimental time. Further, EZ fill showed statistically lower cell viability in 24 and 48 hours compared to AD Seal and in 72 hours compared to all other resin-based root canal sealers. However, there was no correlation between the radiopacity and cytotoxicity of three resin-based root canals sealers (p > 0.05).

These results indicate that resin-based root canal sealer is more biocompatible and has advantage in terms of radiopacity.

The purpose of this study was to assess the background color-interceptive ability and opacity of opaque shade composites (Universal composite, Filtek Z350, Charisma, Clearfil ST, Palpaque Estelite, Esthet-X, and Metafil Flo).

Twenty four background specimens (diameter 5.5 mm, thickness 3.0 mm) with Root dentin Mustard (Bisco, Schaumburg, IL, USA) were made. The CIE L^*a^*b^* value of background specimens was measured by a spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland). Three specimens in every group were filled on the background specimens. The surface color of samples was measured by a spectrophotometer in 3.0 mm and every thickness to 0.5 mm while grinding. The color difference in the background color along with 3.0 mm specimen gauged the masking effect in each thickness while grinding and polishing. The opacity was calculated in 1 mm thick specimens.

The opacity was in the decreasing order of Clearfil ST, Metafil Flo, Filtek Z350, Palpaque Estelite, Universal composite, Charisma, and Esthet-X (p < 0.05). As the thickness get reduced, L^* value showed decreasing, a^* increasing tendency. The surface color difference between pair of the 3.0 mm thick specimen and after grinding in same opaque resin was above 3.3 except Clearfil ST and Metafil Flo. The color difference (ΔE^*) between pair of background specimen and opaque resin builtup specimen showed more than 10.0 regardless kinds and thickness.

The variance in opacity characteristics and color of the opaque composites is dependent upon manufacturer. When using the opaque resin, the optical properties of each material must be considered as well as cavity.

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.