Apical leakage continues to be a topic of great interest, because in spite of the advances in Endodontics, clinical failures still occur. Most failures are probably attributed to the proliferation of bacteria that remain viable after chemical-mechanical preparation and cause periapical tissue irritation. Coronal leakage has aroused researchers’ interest over the last few years, since canals may be re-contaminated after loss of coronal sealing or fracture of the remaining tooth. In this review, the various methodologies used for assessing root canal sealing capacity are critically analyzed, as they are not standardized, which makes it difficult to compare the results obtained when different methodologies are used, even though the same substrate is being assessed. (J. Oral Sci. 48, 93-98, 2006)
To evaluate the effectiveness of Carisolv™ and different auxiliary chemical substances in root canal smear layer (SL) removal. SL was produced in the centre of 40 hemi-disks of bovine root dentine. The samples were divided into four irrigation groups (G): GI (control) - 0.9% NaCl; GII - 1% NaOCl + 0.9% NaCl; GIII - Carisolv™ + 0.9% NaCl; GIV - 1% NaOCl + 10% citric acid solution + 0.9% NaCl. The photomicrographs (SEM analysis) were coded (0 - absence of SL; 1 - moderate SL; 2 - dense SL with visible tubules; 3 - dense SL with no visible tubules). GIV was more effective in SL removal (P < 0.01). It should be noted that GI and GIII obtained score 3 in 100% of the samples (P > 0.01). Conclusion: NaOHCl, citric acid and NaCl solutions, when used together, presented a better performance in the removal of SL when compared to the other solutions. (J. Oral Sci. 48, 99-103, 2006)
Although carcinogenesis of oral squamous cell carcinoma (OSCC) has been studied by many investigators in the past decade, the available evidence about its molecular mechanism is inconclusive. The objective of the present study was to compare expression of Smad4, a signaling molecule of the transforming growth factor β (TGF-β) pathway, between OSCC and normal oral mucosa. We assayed expression of Smad4 in OSCC and normal oral mucosa by performing immunohistochemistry using paraffin-embedded tissue samples. We also compared expression of Smad4 protein between OSCC lines and normal oral keratinocytes, using Western blot analysis. Smad4 expression was observed in only 60% of OSCC tissue samples, whereas it was observed in 82% of normal oral mucosa samples. Reduced Smad4 expression was clearly observed in all OSCC lines, compared with normal oral keratinocytes. These findings suggest that aberration of the TGF-β pathway, as indicated by a reduction or absence of Smad4 expression, promotes carcinogenesis of OSCC. (J. Oral Sci. 48, 105-109, 2006)
The aim of this study was to evaluate the clinical efficacy and safety of a dental drug delivery system (3DS) for the selective reduction of mutans streptococci. Twenty patients with high levels of mutans streptococci in saliva participated. The efficacy of 0.2% chlorhexidine (CHX) delivered by 3DS in reducing the salivary levels of mutans streptococci compared with total streptococci and lactobacilli was investigated. Each subject was treated by professional mechanical tooth cleaning (PMTC) and subsequently individual trays with CHX for 5 min. Salivary bacterial samples were taken at the baseline and weeks 1-12. A significant reduction in the colony count of mutans streptococci was observed during the first 4 weeks compared with the baseline count, while no significant decrease in the count of total streptococci or lactobacilli was found during 12 weeks. In particular, the proportion of mutans streptococci in total streptococci remained low after 12 weeks. Our results indicate that the new 3DS used in combination with PMTC appears to be a promising intraoral drug delivery system which, when used with a low CHX concentration selectively, effectively reduces mutans streptococci in the oral cavity with no adverse effects. (J. Oral Sci. 48, 111-116, 2006)
A study was conducted to compare the efficiency of crude aqueous (CA) and solvent extracts (CM) of clove on the caries-inducing properties of Streptococcus mutans. The cariogenic properties investigated included the cell adhesion, cell-surface hydrophobicity and glucan synthesis activities of S. mutans. There was a significant difference between the effect of the CA and CM extracts on the adhesion of S. mutans (P < 0.05) within a concentration range of 5-15 mg/ml, the CM extract demonstrating a slightly higher inhibitory effect. However, the effect of the CM extract on the cell-surface hydrophobicity of S. mutans was weaker than that of the CA extract. The two extracts were found to reduce the synthesis of water-insoluble glucan (WIG) by almost 50% at a concen-tration as low as 0.5 mg/ml and the CM extract exhibited a significantly higher inhibitory effect than the CA extract (P < 0.05). The present findings indicate that both the CA and CM extracts exert inhibitory effects on the cariogenic properties of S. mutans and that the CA extract is as equally effective as the CM extract. (J. Oral Sci. 48, 117-123, 2006)
The objective of the present study was to assess the influence of the roughness of a loaded surface on crack formation in a mica-based glass-ceramic bonded to a resin composite base. Five different surface roughnesses were created on glass-ceramic discs by serial wet-grinding with silicone carbide abrasives. The thicknesses of the ceramic discs were 1.50 ± 0.01 mm. Resin composite discs were bonded to the ceramic surfaces opposite to the ground surfaces using an adhesive resin composite cement and a silane coupling agent. A compressive load was then applied at the center of the ground ceramic surface. The loads at initial radial and cone crack formations in the ceramic were measured macroscopically. In three of the five groups, the initial radial crack formations could not be observed due to the high roughness of these surfaces. Statistical analysis was performed using Student's t test for initial radial cracks and one-way ANOVA for the cone cracks. There were no significant differences between the two groups for the initial radial cracks or among the five groups for the cone cracks (P < 0.05). The roughness of the loaded surface had no influence on crack formation in the bonded mica-based glass-ceramic. (J. Oral Sci. 48, 125-130, 2006)
This study was conducted to clarify the influence of dentin surface moisture on bond strength of single-step self-etch adhesive systems. The adhesive systems used were Adper Prompt L-Pop (AP), Clearfil tri-S Bond (CT), Fluoro Bond Shake One (FB), G-Bond (GB), and One-Up Bond F Plus (OF). Bovine mandibular incisors were wet-ground with #600 SiC to expose the labial dentin. After rinsing with tap water, the dentin surface was dried with air for 10 sec (Dry condition) or blotted (Wet condition). Adhesives were applied according to each manufacturer's instructions, followed by resin composite polymerization. Ten samples per test group were stored in distilled water at 37°C for 24 h, then shear tested at a crosshead speed of 1.0 mm/min. The data were analyzed by Student's t test and Tukey HSD test at a probability level of 0.05. The mean bond strengths for Dry condition ranged from 13.9 MPa to 18.2 MPa, and those for Wet condition ranged from 7.1 MPa to 18.4 MPa. Significantly lower bond strengths were obtained for the Wet condition for GB, FB, and OF. Failure after the test was commonly due to adhesive breakdown associated with partial cohesive failure in the dentin. These data suggest that air-drying of the dentin surface is appropriate for the adhesive systems tested. (J. Oral Sci. 48, 131-137, 2006)
The aim of the present study was to compare results obtained using the manual point-counting method with results obtained using the semi-automated segmentation method, in the quantitative evaluation of histological sections by light microscopy. The tongues of 40 rats (Ratus norvergicus) were processed using the paraffin technique, in which a 5-μm-thick tissue slice cut from each tongue is stained with picrosirius and methyl green. Three digital images were captured randomly from each section, which were later converted to black-and-white. The collagen fibers shown in each image were quantified using the semi-automated segmentation method and the manual point-counting method. The results obtained using the 2 different quantification methods were compared using the paired t-test and Pearson's correlation test, with statistical analysis using the methods of Bland and Altman. The t-test indicated that there was no significant difference in results between the 2 different quan-tification methods. Pearson's correlation test indicated a strong correlation (r = 0.987), and a comparison of the methods using the Bland and Altman plot indicated no significant error. These findings indicate that both quantification methods can be reliably used to evaluate tissue sections, without discrepancies between the 2 methods. (J. Oral Sci. 48, 139-143, 2006)
Nucleotide sequences of the hypervariable region in the D-loop of mitochondrial DNA (mtDNA) were analyzed using DNA extracted from 140 old dental pulp samples. These sequences were compared with the sequence reported by Anderson et al. Nucleotide substitution in the HV1 region was identified at 77 positions. A C-to-T transition at position 16223 (C16223T) was most frequently detected (77.9%). Fourteen types of C-stretch sequence patterns were detected and the same sequence as Anderson had the highest frequency (57.9%). In the HV2 region, base transitions were identified at 56 positions. A263G was identified in all samples. Seven types of C-stretch were detected, but none had the same sequence as Anderson. In the HV3 region, base transitions were identified at 21 positions. T489C was most frequently identified (64.3%). Five types of C-stretch were detected, and the same sequence as Anderson accounted for 92.9%. The 140 samples were classified into 128 kinds by the sequence patterns of the HV region. Next, using the blood and oral mucosa epithelium from 23 subjects comprising four generations in a family line, the hereditary relationship of mtDNA was examined. All mtDNA types of the first-generation mother were infallibly inherited by the fourth generation. (J. Oral Sci. 48, 145-152, 2006)
The aim of this work was to investigate the association between recurrent aphthous stomatitis (RAS) and salivary thiocyanate levels. The sample comprised men and women of age ranging from 15 to 55 years, who were allocated to four groups: 28 patients in RAS active phase (group 1); 28 patients in RAS remission phase (group 2); 29 smokers (group 3); 26 non-smokers without RAS (group 4). Samples of whole saliva mechanically stimulated were collected, and thiocyanate levels were measured. The results were analyzed by ANOVA and paired t-test. Mean salivary thiocyanate values were 0.55 mM, 0.64 mM, 2.36 mM and 0.96 mM in groups 1 (active RAS), 2 (remission RAS), 3 (smokers) and 4 (control), respectively. There was no significant difference in thiocyanate levels when groups 1 and 2 were compared with group 4. Group 3 showed a significantly higher thiocyanate concentration when compared with groups 1, 2 and 4 (P < 0.05). There was no significant difference in thiocyanate levels between groups 1 and 2 (P > 0.05). It is therefore suggested that there is no association between RAS and salivary thiocyanate levels. (J. Oral Sci. 48, 153-156, 2006)
An unusual case of isolated plexiform neurofibroma arising in the oral cavity without other clinical manifestations or family history of neuro-fibromatosis-1 (NF-1) is described. The tumor was histopathologically analyzed and an immunohisto-chemical panel comprising S-100 protein, epithelial membrane antigen (EMA), collagen IV, and CD34 was performed. Typical features of plexiform neurofibroma characterized by enlarged nerve fascicles composed of elongated nuclei and scant cytoplasm cells were identified. Subjacent to the oral epithelium, tactile-like bodies were also detected. On the basis of this report, we would like to emphasize that plexiform neurofibroma can occur in the oral cavity as a benign isolated tumor in patients without other stigmata of NF-1. (J. Oral Sci. 48, 157-160, 2006)
Cleidocranial dysplasia (CCD) is a rare syndrome usually caused by an autosomal dominant gene, although 40% of cases of CCD appear spon-taneously with no apparent genetic cause. This condition is characterized by several cranial malformations and underdevelopment, absence of the clavicles, and mul-tiple supernumerary and impacted permanent teeth. The diagnosis of this condition is usually based on the presence of the main features (supernumerary teeth, partial or total absence of one or both the clavicles, and bony malformations) and on clinical and familial evidence. The bony and dental features of CCD may be visualized on radiographic images of the face and skull. Here, we present a familial case of CCD and discuss the importance of dental radiographs in diagnosis of the condition. (J. Oral Sci. 48, 161-166, 2006)
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