The aim of this study was to measure the dentinal tubular fluid flow (DFF) during and after amalgam and composite restorations. A newly designed fluid flow measurement instrument was made. A third molar cut at 3 mm apical from the CEJ was connected to the flow measuring device under a hydrostatic pressure of 15 cmH₂O. Class I cavity was prepared and restored with either amalgam (Copalite varnish and Bestaloy) or composite (Z-250 with ScotchBond MultiPurpose: MP, Single Bond 2: SB, Clearfil SE Bond: CE and Easy Bond: EB as bonding systems). The DFF was measured from the intact tooth state through restoration procedures to 30 minutes after restoration, and re-measured at 3 and 7days after restoration.

Inward fluid flow (IF) during cavity preparation was followed by outward flow (OF) after preparation. In amalgam restoration, the OF changed to IF during amalgam filling and slight OF followed after finishing.

In composite restoration, application CE and EB showed a continuous OF and air-dry increased rapidly the OF until light-curing, whereas in MP and SB, rinse and dry caused IF and OF, respectively. Application of hydrophobic bonding resin in MP and CE caused a decrease in flow rate or even slight IF. Light-curing of adhesive and composite showed an abrupt IF. There was no statistically significant difference in the reduction of DFF among the materials at 30 min, 3 and 7 days after restoration (P > 0.05).

The purpose of this study was to compare the microleakage of low and high viscosity flowable resins in class V cavities applied with 1-step adhesives.

Forty class V cavities were prepared on the cervices of buccal and lingual surfaces of extracted molar teeth and divided into four groups (n=8). Cavities were restored with AQ Bond Plus/Metafil Flo α, G-Bond/UniFil LoFlo Plus (Low flow groups), AQ Bond Plus/Metafil Flo and G-Bond/UniFil Flow (High flow group), respectively.

Specimens were immersed in a 2% methylene blue solution for 24 hours, and bisected longitudinally. They were observed microleakages at the enamel and dentinal margins.

In conclusion, the low viscosity flowable resins showed lower marginal microleakage than do the high viscosity flowable resins in class V cavities.

The purpose of this study was to evaluate the effect of soft chelating irrigant on the sealing ability of root fillings by using a glucose leakage test.

A total of 45 single-rooted teeth were selected for the study. The teeth were decoronated leaving a total length of 13mm. The root canals prepared using K3 NiTi rotary instruments to an apical dimension of size 45(0.06 taper). The specimens were then randomly divided into 3 experimental groups of 13 roots each and 2 control groups of 3 roots each. Specimen in each group were prepared with different irrigation protocols : group 1, 2.5% NaOCl; group 2, 2.5% NaOCl and 17% EDTA; group 3, 2.5% NaOCl and 15% HEBP. The root canals were filled with gutta-percha and AH Plus sealer using lateral condensation. After 7 days in 37℃, 100% humidity, the coronal-to-apical microleakage was evaluated quantitatively using a glucose leakage model. The leaked glucose concentration was measured with spectrophotometry at 1, 4, 7, 14, 21 and 28 days.

There was a tendency of increase in leakage in all experimental groups during experimental period. HEBP-treated dentin showed no significant difference with EDTA-treated dentin during experimental period. From the 21th day onward, HEBP-treated dentin showed significantly lower leakage than smear-covered dentin. HEBP-treated dentin displayed a similar sealing pattern to EDTA-treated dentin and a better sealing ability than smear-covered dentin. Consequently, a soft chelator(HEBP) could be considered as the possible alternative to EDTA.

This study examined the influence of the storage methods on the viability of oral epithelial cells using conventional cell freezing storage, slow freezing preservation, rapid freezing preservation, and slow freezing preservation with a pressure of 2 Mpa or 3 Mpa. The cell viability was evaluated by cell counting, WST-1 and the clonogenic capacity after 6 days of freezing storage. After 6 days, the frozen cells were thawed rapidly, and the cell counting, WST-1, and clonogenic capacity values were measured and compared.

The results from cell counting demonstrated that conventional cryopreservation, slow freezing under a 2 Mpa pressure and slow freezing under a 3 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p<0.05).

The purpose of this study is to compare the antibacterial effect of Listerine® on two microorganisms (P. gingivalis and E. faecalis) with various root canal irrigants (NaOCl, CHX, EDTA) and to identify possibility of using Listerine® as a root canal irrigant. Porphyromonas gingivalis ATCC 3327 and Enterococcus faecalis ATCC 29212 were used in this experiment. For the test irrigants, 0.5%, 1%, 2.5%, 5.25% NaOCl, 0.1%, 0.2%, 1%, 2% CHX, 0.5M EDTA (18.6% EDTA) and Listerine® were prepared. Distiled water was used as control. Two methods-1) Comparison of turbidity in broth and 2) Agar diffusion test-were used to determine the extent of antibacterial effect of Listerine® and to compare it with that of NaOCl, CHX, and EDTA. All solutions tested were effective against two bacterial strains compared with control (p<0.001). Any concentration of NaOCl, CHX, and EDTA showed similarly high effectiveness against all bacterial strains. In all experiment, Listerine® showed significantly low antibacterial effect compared with the other root canal irrigants (p<0.05).

In conclusion, the results reflect remarkably low antibacterial effect of Listerine® as compared with root canal irrigants in general so it is not suitable for the root canal irrigant.

The purposes of this study were to compare the efficacy of irrigation systems by removing a calcium hydroxide (Ca(OH)₂) paste from the apical third of the root canal and the effect of the patency file. Sixty single rooted human teeth were used in this study. The canals were instrumented by a crown-down manner with .04 taper ProFile to ISO #35. Ca(OH)2 and distilled water were mixed and placed inside the root canals. The teeth were divided into 6 groups according to the root canal irrigation system and the use of patency file as follows: group 1 - conventional method; group 2 - EndoActivator^®; group 3 - EndoVac^®; group 4 - conventional method, patency; group 4 - EndoActivator^®, patency; group 6 - EndoVac^®, patency. All teeth were irrigated with sodium hypochlorite. After the root canal irrigation, the teeth were split in bucco-lingual aspect. Percentage of the root canal surface coverage with residual Ca(OH)2 until 3 mm from working length was analyzed using Image Pro Plus ver. 4.0. Statistical analysis was performed using the One-way ANOVA, t-test and Scheffe's post-hoc test. Conventional groups had significantly more Ca(OH)2 debris than EndoActivator^®, EndoVac^® groups. There was no significant difference between EndoActivator^® and EndoVac^® groups. Groups with patency file showed more effective in removing Ca(OH)₂ paste than no patency groups, but, it was no significant difference. This study showed that EndoActivator^® and EndoVac^® systems were more effective in removing Ca(OH)2 paste from the apical third of the root canal than conventional method.

Clinical suggestion for the limitation of application time of NaOCl solution is needed to avoid large reductions in resin-dentin bond strength. The aim of this study was to measure the change of µ-tensile bond strength after the various application time of 5.25% NaOCl solution to pulp chamber dentin in endodontic access cavity, and to evaluate the effect of 10% sodium ascorbate application for 10 min on bond strength after the treatment of 5.25% NaOCl solution. In this experiment, there were no statistical differences(p>0.05) in bond strengths between upper chamber dentin and lower chamber dentin. NaOCl-treated group for 20 min did not show any significant decrease(p>0.05) in bond strength than non-treated control group. In contrast to that, bond strengths of NaOCl-treated groups for 40 & 80 min were significantly lower(p<0.05) than that of non-treated control group.

10% sodium ascorbate retreated group for 10 min after 5.25% NaOCl application for 40 min to chamber dentin showed the recovery of bond strength significantly. However, the bond strength of sodium ascorbate retreated group after 5.25% NaOCl application for 80 min was still significantly lower(p<0.05) compared to the non-treated control group, which means the reductions in resin-dentin bond strength were not fully reversed. On the contrary, sodium ascorbate retreated group after 5.25% NaOCl application for 5 min showed significantly higher(p<0.05) bond strength compared to the control group, which demonstrates its superior recovery effect. In SEM exminations of specimens retreated with 10% sodium ascorbate after NaOCl application for 40 & 80 min showed that resin tags were formed clearly and densely, but weakly in density and homogeneity of individual resin tag compared to the control specimen.

The aim of this vitro-study is to evaluate the effects of fluoride on remineralization of artificial dentine caries. 10 sound permanent premolars, which were extracted for orthodontic reason within 1 week, were used for this study. Artificial dentine caries was created by using a partially saturated buffer solution for 2 days with grounded thin specimens and fractured whole-body specimens. Remineralization solutions with three different fluoride concentration (1 ppm, 2 ppm and 4 ppm) were used on demineralized-specimens for 7 days. Polarizing microscope and scanning electron microscope were used for the evaluation of the mineral distribution profile and morphology of crystallites of hydroxyapatite.

The results were as follows :

When treated with the fluoride solutions, the demineralized dentine specimens showed remineralization of the upper part and demineralization of the lower part of the lesion body simultaneously.

During the last two decades, there has been an increasing interest in the impact of oral health on atherosclerosis and subsequent cardiovascular disease (CVD). To date, some periodontal pathogens including Porphyromonas gingivalis (P. gingivalis) have been reported to be relevant to CVD. Porphyromonas endodontalis (P. endodontalis), which shares approximately 87% sequence homology with P. gingivalis, is mostly found within infected root canals. However, recent studies reveal that this pathogen also resides in the dental plaque or periodontal pocket in patients with periodontitis. It has been shown that P. endodontalis invades human coronary artery endothelial cells (HCAEC) and coronary artery smooth muscle cells (CASMC). To evaluate whether P. endodontalis can participate in the progression of atherosclerosis and CVD, we examined the changes in transcriptional gene expression profiles of HCAEC responding to invasion by P. endodontalis in this study.

The following results were obtained.

Porphyromonas endodontalis was invasive of HCAEC.

Thus, these results show that P. endodontalis presents the potential to trigger and augment atherosclerosis leading to CVD.