This study compared the microtensile bond strength (μTBS) and microscopic change of two 2-step and two 1-step self-etching adhesives to dentin according to storage times in distilled water.

Occlusal dentin was exposed in 48 human molars. They were divided to four groups by different adhesives: SE Bond group (Clearfil SE Bond), AdheSE group (AdheSE), Adper group (Adper Prompt L-Pop), and Xeno group (Xeno III). Each group was stored in 37℃ distilled water for 1, 15, and 30 days.

Resin-bonded specimens were sectioned into beams and subjected to μTBS testing with a crosshead speed of 1 mm/minute. For SEM observation, one specimen was selected and sectioned in each group after each stroage time. Resin-dentin interface was observed under FE-SEM.

In all storage times, mean μTBS of SE group was significantly higher than those of other groups (p < 0.05). There was no significant difference between mean μTBS of SE group and AdheSE group among all storage times, but significant difference between 1- and 30-day storage in mean μTBS of Adper group and Xeno group (p < 0.05). For 1-and 15-day storage, all groups showed the close adaptation between resin-dentin interfaces. For 30-day storage, resin-dentin interfaces showed wide gap in Adper group and separate pattern in Xeno III group.

Established microleakage tests have their own disadvantages. In this study, 3D reconstruction method was tried to overcome these disadvantages.

Four types of microleakage tests were used and relationships among them were estimated: penetrated dye volume; marginal adaptability; degree of dye penetration and relative penetrated length to cavity wall.

Twenty-four Class V cavities were bulk filled with composite (Esthet X) following surface treatments: N group (no treatment); E group (etching only); T group (etching + Prime & Bond NT). 50% silver nitrate was used as a dye solution after thermocycling (5℃ & 55℃, 1,000 times). Teeth were serially ground with a thickness of 0.2 mm. Volume of dye penetration was estimated from a three-dimensionally reconstructed image with a software (3D-DOCTOR). Percentage of margin without gap was estimated from SEM and degree of dye penetration and the relative length of dye penetration to overall cavity wall were also estimated.

ANOVA and Scheffe test for dye volume, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships among methods were used.

The results were as follows:

1. Dye penetration could be seen from several directions, furthermore, its volumetric estimation was possible.

2. Reverse relationship was found between dye volume and marginal quality (r = -0.881 / p = 0.004).

3. Very low relationship was seen between dye volume and two-dimensional tests (degree of dye penetration and relative length). However, 2D evaluation methods showed high relationship (p = 0.002-0.054) each other.

4. Three times vertical section could be recommended as a 2D test.

The aim of this study is to compare the adaptability of thermoplasticized injectable gutta-percha technique to the canal walls in ribbon-shaped canals.

Thirty resin models simulated ribbon-shape canals were instrumented to #40 using .06 taper Profile systems. Three groups of each 10 resin models were obturated by the lateral condensation technique(LC) and the two thermoplasticized injectable gutta-percha technique; Ultrafil Endoset+Obtura II(EO) and Ultrafil Firmset(UF), respectively.

After resin model were kept at room temperature for 4 days, they were resected horizontally with microtome at 1, 2, 3, 4 and 5mm levels from apex. At each levels, image of resected surface were taken using CCD camera under a stereomicroscope at ×40 magnification and stored. Ratio of the area of gutta-percha was obtained by calculating area of gutta-percha cone to the total area of canal using digitized image-analyzing program. The data were collected then analyzed statistically using One-way ANOVA.

The results were as follows.

1. At 1mm levels, there was no statistically significant difference in the mean ratio of gutta-percha among the groups.

2. At 2mm level, EO showed the highest mean ratio of gutta-percha (p<0.05) and there was no significant difference between LC and UF.

3. At 3, 4, 5mm levels, EO and UF had significantly greater mean ratio of gutta-percha than LC(p<0.05) and there was no significant difference between EO and UF.

In conclusion, the thermoplasticized injectable gutta-percha techniques demonstrated relatively favorable adaptability to canal walls than lateral condensation technique in ribbon-shaped canals except for 1mm level.