The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT).
Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired
The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (
The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.
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.