The bond strengths in treated with air-powder polished group and phosphoric acid etched group were significantly higher than that of the group in laser irradiation alone.

Wound healing is a dynamic process, and a variety of growth factors have a significant impact on the process. Although the WNT family has a multitude of effects on the state of various physiological pathways, the expression and role of WNT in wounded tissue have remained an enigma. The aim of this study was to assess the expression and localization of WNTs in a murine model of wound healing. RNA isolated from fullthickness cutaneous wounds from day 1 to day 21 postwounding were subjected to reverse transcriptionpolymerase chain reaction, and expression of WNT3, 4, 5a, and 10b were observed. Immunohistochemistry localized WNT10b to regenerating epithelial cells on day 1 and 3, and WNT4 on day 3 and 5. WNT4 also reacted with fibroblast-like cells beneath the epithelium. The cytoplasmic staining of b-catenin, a WNT signaling molecule, in the epithelial cells indicates an activation of the WNT signaling pathway. Among target genes downstream of the pathway, matrix metalloproteinases (MMPs) degrade and remodel the extracellular matrix during wound healing. Gelatin zymography showed that MMP9 was expressed from day 1 to day 5. MMP-2 was continuously expressed, but maximally up-regulated at day 5. Activation of MMP-2 coincided with expression of membrane-type 1 MMP, suggesting an involvement of WNTs in this proteolytic cascade. Therefore, WNTs may contribute to the process of wound healing in a spatiotemporal manner. (WOUND REP REG 2005;13:491-497) ECM Extracellular matrix GAPDH Glyceraldehyde 3-phosphate dehydrogenase MMP Matrix metalloproteinase MT1-MMP Membrane type 1-MMP RT-PCR Reverse transcription-polymerase chain reactionWound healing is a dynamic and interactive process requiring the collaboration of effector molecules from many different tissues and cell lineages. The behavior of each component contributes cell types during the phases of proliferation, migration, matrix synthesis, and contraction, as well as growth factor and matrix signals present at a wound site. Numerous studies have indicated that the combined actions of various growth factors, properly timed, are indispensable for complete wound closure and new tissue formation. 1,2 Although the use of recombinant growth factors could be a next avenue to accelerate the wound healing process, clinical application of these factors has just begun. 2 Understanding detailed molecular mechanisms for the processes of wound repair is a prerequisite for the development of novel therapeutic strategies. The WNT family of genes has been identified as an oncogenic gene family that transmits its signals through binding of the translated protein products to cell surface receptors. WNT members are classified into two groups, canonical and other, according to their downstream signaling pathway. 3 WNT3 and WNT10b activate the canonical signaling pathway by inhibiting the kinase activity of glycogen synthase kinase 3-b and increasing the cytoplasimc pool of free b-catenin. 4,5 WNT5a stimulates G protein-dependent Ca þþ signaling machinery. 6 Downstream signaling

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The purpose of this study was to examine the ability of Er:YAG laser to remove root canal filling materials. The root canals of 21 extracted human anterior teeth were enlarged, and then obturated with gutta-percha points and sealer by lateral condensation. Filling materials were removed from root canals using Er:YAG laser irradiation at three energy output levels (30, 40, and 50 mJ/ pulse), and the corresponding time required for material removal at each energy output level was recorded. The amount of remaining filling material and the degree of dentin ablation in the canal wall were assessed using microfocus X-ray CT before and after removal. At 30 mJ, the time required for root canal filling material removal was significantly longer than at energy outputs of 40 and 50 mJ (p<0.01). On filling material remnants and the degree of dentin ablation, these parameters were not significantly different among the three energy outputs. In conclusion, these results suggested that Er:YAG laser irradiation is capable of removing root canal filling materials.

This study sought to investigate the setting progress and sealing ability of hydraulic temporary sealing materials used in endodontic treatment: Lumicon, Caviton, and HY-Seal. To evaluate setting progress, the materials were filled into glass tubes with one end sealed and immersed in water. After immersion, a measurement apparatus was inserted from the nonimmersed end and the set area was determined by subtracting the unset area from the sample thickness. To evaluate sealing ability, materials were filled into glass tubes and divided into four groups based on different immersion times. Thermal cycling and dye penetration were performed. At 7 days, the setting depths of HY-Seal and Caviton were almost equivalent to full sample thickness, while that of Lumicon was only half of full sample thickness (p<0.01). On sealing ability, Lumicon ranked the highest followed by Caviton, whereas HY-Seal was unstable (p<0.01). These results suggested that there was no correlation between setting progress and sealing ability.