Influence of microhardness and fluoride content of tooth structure by fluoride-containing restorative materials / 대한치과보존학회지

The purpose of this study was to compare the microhardness and the fluoride content of enamel and dentin around fluoride- or non fluoride-containing restorations. Forty extracted human teeth were used and prepared cervical cavities on proximal surface. Experimental teeth were divided into five groups. Group 1 : Prime & Bond NT and Z100, Group 2 : Prime & Bond NT and F2000, Group 3 : Scotchbond Multi-Purpose and Z100, Group 4 : Scothcbond Multi-purpose and F2000, Group 5 : Fuji II LC. The cavities were filled with dentin adhesives and restorative materials. After each tooth was bisected, one half was tested microhardness and the other half was analyzed the fluoride at the enamel and dentin by an EPMA-WDX device. The results were as follows: 1. There was no statistical difference among the microhardness of enamel surface in all group. 2. The microhardness at dentin of 100 microm point in Group 2 and 20 microm point in Group 4 was lower than that of normal dentin (p>0.05). 3. There was no statistical difference among the fluoride content of enamel surface in all group. 4. The fluoride content at the dentin of 30 microm point in Group 2 and 5 were higher than those at 100 microm and 200 microm point in Group 2 and normal dentin (p<0.05). 5. At the dentin of 30 microm point, Group 2 showed higher fluoride content than Group 1 and 3, and Group 5 showed higher fluoride content than other groups.

Influence of appication time of self-etching primers on dentinal microtensile bond strength / 대한치과보존학회지

This study evaluated the influence of application time of self-etching primers on microtensile bond strength (microTBS) to dentin using three self-etching primer adhesive systems. Dentin surfaces were exposed from forty-eight human molars. They were conditioned with three self-etching primers (Clearfil SE Bond [SE], Unifil Bond [UF], Tyrian SPE + One Step Plus [TY]) and different primining times (10s, 20s, 30s and 40s). Composite resins were bonded to dentin surfaces and specimens were made. microTBS was tested and statistically compared using by one-way ANOVA and Tukey's Test The results of this study presented that priming time for 10s in SE and UF groups and for 30s and 40s in TY group was highly decreased microTBS to dentin.

Marginal microleakage of single step adhesives / 대한치과보존학회지

This study evaluated the marginal microleakage of five single step adhesives. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on both buccal and lingual surfaces of extracted human molar teeth. Prepared teeth were randomly divided into five groups and restored using one of the single step adhesives and composite resins: Prompt L-Pop/Filtek Z-250 (Group 1), AQ Bond/Metafil CX (Group 2), One-Up Bond F/Palfique Toughwell (Group 3), Futurabond/Admira (Group 4), Xeno III/Spectrum TPH (Group 5). The restored teeth were thermocycled. Microleakage was assessed by dye penetration using 2% methylene blue dye solution. The teeth were bisected buccolingually and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kruskal-Wallis test and Mann-Whitney tests. The results of this study were as follows; 1. Microleakage of enamel margins in group 3 was statistically higher than that in groups 1, 2, 4, 5 (p < 0.05). 2. Microleakage of dentin margins in group 1 was statistically higher than that in groups 2, 5, and that in group 3 was statistically higher than that in groups 2, 4, 5 (p < 0.05). 3. Dentin marginal microleakage was higher than enamel marginal microleakage in all experimental groups. In conclusion, Prompt L-Pop showed the least leakage at enamel margin, and AQ Bond showed at dentin margin in this study. Marginal miroleakage in dentin was higher than that in enamel.

Effect of rewetting agent on dentinal microtensile bond strength / 대한치과보존학회지

This study investigated that the effect of rewetting agent on dentinal microtensile bond strength (microTBS). Human molars were sectioned to expose the superficial dentin surfaces. Samples were divided into two groups according to type of adhesives-Single Bond (S) and One-Step (O)], and again subdivided into five groups by different dentin surface treatment-dry for 15s (D), blot dry (BD) or dry for 15s, and rewet with different rewetting agents [distilled water (DW), Gluma Desensitizer (GD) and Aqua-Prep (AP)] for 30s. After application of adhesive, composite resin was built up on the bonding surface. Each tooth was sectioned to obtain stick with 1 mm2 cross sectional area and the microTBS was determined by EZ test. In the S group, the mean microTBS of GD, AP and BD group was significantly higher than that of DW and D group (p < 0.05). In the O group, the mean microTBS of AP, GD, BD and DW group was significantly higher than that of D group (p < 0.05). The data suggested that Gluma Desensitizer and Aqua-Prep could be successfully used as rewetting agents, and Distilled water could be acceptable in aceton based adhesive system only.

The effect of delayed composite resin filling on microtensile bond strength / 대한치과보존학회지

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (microTBS) after applied the adhesive. The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces, and composite resin were constructed immediately (group 1) or 5 min., 10 min., 15 min., 20 min. and 30 min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about 1mm2. The microTBS test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95% significance level. The results suggested that the microTBS of Single-Bond to dentin was decreased when the composite resin was constructed 20 min. and 30 min. after Single-Bond was applied. But the microTBS of One-Step was not affected by delayed composite resin filling.

Effect of wetness on the enamel bonding / 대한치과보존학회지

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface. V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups: D group (air dry for 10-15 s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15 s and rewet with Aqua-Prep F for 20 s). Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p 0.05). At the enamel-resin interface, group D showed the gap of 2 microm thickness, but group BD and DR showed close adaptation. In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

The Anatomy of the Lumbar Epidural Space using Magnetic Resonance Imaging / 대한마취과학회지

MRI(Magnetic Resonance Imaging) have provided for greater image resolution, detailed tissue contrast without use of contrast media and images acquired in any plane. The purpose of this study was to examine the anatomy and dimension of the epidural space using MRI(Magnetic Resonance Imaging) and to compare the information obtained with that from other investigative technique. The anatomy of the lumbar epidural space was studied retrospectively using lumbar MRI scans of 90 patients. The epidural width(E.W.) is divided into three distance between the anterior surface of the ligamentum flavum and the dura at the caudal end of the lumbar segment(A), at the mid point of the ligamentum flavum(B) and at the cranial end of the lumbar segment(C). The distance from skin to supraspinous ligament(S-L) and from supraspinous ligament to epidural space(L-E) were measured. And then with adding both the distance, We measured the distance from skin to epidural space(S-E). Results were as follows; I) Posterior to the dural sac, epidural fat which is of high signal(white) on Tlw(T1 weighted) image is demonstrated at levels Tl I-T12 to L5-Sl giving 'Saw toothed' pattem to the epidural space. The fat is divided into segments by the interposing laminar, and the epidural space is deeper at cranial end than caudal end. 2) It was the relatively wide epidural space in L2-3 and L3-4 level, and the narrowest epidural space in L5-Sl level. 3) The distance from skin to supraspinous ligament was noted marked variation(2-40mm) according to the individual disparity. And the distance from supraspinous ligament to epidural space is 17-43mm. In distance from skin to epidural space, the most narrow place is Ll-21evel (37.95+/-7.65mm). The most deep place is IA-5 level(46.35+/-7.20mm). As the age increase, epidural width is decreased at L3-4 level (p<0.05).