Accuracy in defining a disease makes it easier to study and understand. Similarly, with injuries to the teeth, a comprehensive classification is an aid to correct diagnosis and treatment planning. A thorough review of various classifications of tooth fractures shows that, despite an emphasis on traumatic dental injuries, a consensus needs to be arrived at, especially among clinicians and general/family dentists. The ideal classification would be applicable to both primary and permanent dentition, based on tooth fractures in both the horizontal and vertical planes, encompassing all possible sites, easy to comprehend, communicable amongst health professionals and clinically relevant. With recent improvements in conservative techniques, it is now clinically possible to preserve natural teeth even if they have been horizontally or vertically fractured, and thus an in-depth understanding and knowledge of tooth fractures, together with a simplified classification, is now more than ever essential. (J Oral Sci 52, 517-529, 2010)
Zirconium dioxide (zirconia) ceramics are currently used for fixed restorations as a framework material due to their mechanical and optical properties. This review article describes the current status of zirconia-based fixed restorations, including results of current in vitro studies and the clinical performance of these restorations. Adaptation of zirconia-based restorations fabricated with CAD/CAM technology is within an acceptable range to meet clinical requirements. In terms of fracture resistance, zirconia-based fixed partial dentures (FPDs) have the potential to withstand physiological occlusal forces applied in the posterior region, and therefore provide interesting alternatives to metal-ceramic restorations. Clinical evaluations have indicated an excellent clinical survival of zirconia-based FPDs and crown restorations. However, some clinical studies have revealed a high incidence of chipping of veneered porcelain. Full-coverage zirconia-based restorations with adequate retention do not require resin bonding for definitive cementation. Resin bonding, however, may be advantageous in certain clinical situations and is a necessity for bonded restorations, such as resin-bonded FPDs. Combined surface treatment using airborne particle abrasion and specific adhesives with a hydrophobic phosphate monomer are currently reliable for bonding to zirconia ceramics. Further clinical and in vitro studies are needed to obtain long-term clinical information on zirconia-based restorations. (J Oral Sci 52, 531-539, 2010)
Adult stem cells are multipotent and can be induced experimentally to differentiate into various cell lineages. Such cells are therefore a key part of achieving the promise of tissue regeneration. The most studied stem cells are those of the hematopoietic and mesenchymal lineages. Recently, mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, and dental follicle. The dental follicle is a loose connective tissue that surrounds the developing tooth. Dental follicle stem cells could therefore be a cell source for mesenchymal stem cells. Indeed, dental follicle is present in impacted teeth, which are commonly extracted and disposed of as medical waste in dental practice. Dental follicle stem cells can be isolated and grown under defined tissue culture conditions, and recent characterization of these stem cells has increased their potential for use in tissue engineering applications, including periodontal and bone regeneration. This review describes current knowledge and recent developments in dental follicle stem cells and their application. (J Oral Sci 52, 541-552, 2010)
This in vitro study aimed to analyze the effects of application of xylitol varnishes and solutions to protect against enamel erosion. Twelve bovine enamel specimens were pre-treated with 5% NaF-Duraphat varnish, 10% xylitol varnish, 20% xylitol varnish, placebo varnish, 5% NaF solution, 10% xylitol solution or 20% xylitol solution. The varnishes and solutions were applied for 6 h and 1 min, respectively. Controls remained untreated (n = 12). Specimens were then subjected to erosive demineralization (Coca-Cola, 4 × 90 s/d) and remineralization (artificial saliva, 2 h) cycling for 10 days. After 5 days, the varnishes and solutions were reapplied. After reapplication, two specimens per group were analyzed by SEM. Enamel loss was measured profilometrically after the 5th and 10th days. Data were then analyzed statistically by ANOVA and Tukey's post-hoc test (n = 10, P < 0.05). After the 5th day, all varnishes and 20% xylitol solution significantly reduced the enamel loss when compared to the placebo varnish/control. After 10 days of erosive pH cycling, both xylitol varnishes and solutions significantly reduced the enamel erosion when compared with the control. However, 10% xylitol solution produced a smooth layer on eroded enamel and significantly reduced the enamel erosion when compared to the placebo varnish/control. Xylitol thus appears to be a good option to partially reduce enamel erosion. (J Oral Sci 52, 553-559, 2010)
The Gram-negative anaerobic bacterium Porphyromonas gingivalis is a major causative agent of periodontal disease. Although P. gingivalis is an anaerobic bacterium, it exhibits aerotolerance and can survive in periodontal pockets, indicating that it must possess a mechanism for protection against oxidative stress, although the precise details are still unclear. Recently, phosphorylation signaling has been implicated in the regulation of bacterial virulence. In the present study, to examine the effect of oxidative stress on phosphorylation of proteins in P. gingivalis, we analyzed oxidative stress-induced alterations of phosphorylated proteins using two-dimensional electrophoresis with phosphoprotein staining coupled with MALDI-TOF mass spectrometry analysis. Among the phosphorylated proteins analyzed, we identified an increase in phosphorylation of the ABC transporter, ATP-binding protein (PG0258). Since the ABC transporter family is known to be involved in lipopolysaccharide (LPS) biosynthesis, we examined the level of LPS using an endotoxin assay and found that LPS production was increased in P. gingivalis. Our present findings suggest that the early response of P. gingivalis to oxidative stress could trigger the development and progression of periodontal disease through enhancement of LPS production by phosphorylation of the ABC transporter, ATP-binding protein. (J Oral Sci 52, 561-566, 2010)
The aim of this study was to evaluate the seal of a 4-mm Mineral Trioxide Aggregate (MTA) filling after post space preparation. Forty single-rooted premolar teeth without curved root anatomy and fractures were selected. The root length was standardized to 12 mm by removing excess from the apical end. The roots were instrumented to a 50 K-file by the step-back technique. The roots were randomly divided into groups A and B, of fifteen each. In group A, the canals were obturated with 7 mm of white MTA. After 24 h, 3 mm of MTA was removed to simulate post space preparation using a long shank diamond round bur. In group B, the canals were filled with 4 mm of white MTA. All samples were attached to a fluid filtration device. Measurements (μl min-1 cm H2O-1) were taken every 2 min, for 10 min and data were analyzed by an independent t-test (P > 0.05). Fluid transport averaged in groups A and B at 9.2 × 10-4, and 11.8 × 10-4 μl min-1 cm H2O-1, respectively. Independent t-test showed no significant difference between the groups (P < 0.05). Removing set MTA using a round bur for post space preparation does not affect its sealing ability, when 4 mm of MTA remains. (J Oral Sci 52, 567-570, 2010)
The present study was conducted to evaluate the effect of acidic primers on adhesive bonding to sintered alumina. Alumina disk specimens were primed with one of the following acidic materials: Acryl Bond, All Bond II Primer B, Alloy Primer, Estenia Opaque Primer, Eye Sight Opaque Primer, M.L. Primer, MR. Bond, and Super-Bond Liquid. The disks were bonded with an adhesive resin (Super-Bond) initiated with a tri-n-butylborane (TBB) derivative, and bond strengths were determined. Average bond strength before thermocycling varied from 42.9 to 44.3 MPa, whereas post-thermocycling bond strength ranged from 22.0 to 42.8 MPa. Of the nine groups assessed, reduction of bond strength after thermocycling was not significant in three: Alloy Primer, Estenia Opaque Primer, and Eye Sight Opaque Primer. It can be concluded that phosphate-based primers are recommended for bonding sintered alumina with Super-Bond resin. (J Oral Sci 52, 571-576, 2010)
Polyamide denture base materials are more flexible than the commonly used poly (methyl methacrylate) (PMMA). However polishability of polyamides has not been examined adequately. This study investigated the surface roughness (Ra) and clinical acceptability of samples of a polyamide denture base material and PMMA fabricated by injection moulding and traditional heat processing systems, respectively. Half of each sample surface was polished using the conventional technique (lathe with pumice followed by high shine buffs) and the other half was left unpolished. A profilometer was used to measure Ra along 3 tracks on each surface before and after polishing. Two-way ANOVA was used to compare the two surfaces of the two materials for variations in Ra values. Polyamide denture base material when polished with conventional laboratory technique became more than 7 times smoother whereas processed PMMA when polished became more than 20 times smoother using the same polishing technique. However the surface roughness of polyamide is well within the accepted norm of 0.2 μm Ra. Polyamide produces a clinically acceptable smoothness after conventional polishing by lathe. (J Oral Sci 52, 577-581, 2010)
In periodontal disease, gingival fibroblasts activated by the Gram-negative anaerobic bacterium Porphyromonas gingivalis induce overexpression of matrix metalloproteinase-2 (MMP-2), which is involved in inflammatory progression. This process is followed by tissue destruction and bone loss. In the present study, we investigated the in vitro effect of the ethanolic Kaempferia pandurata Roxb. extract on expression of MMP-2 in P. gingivalis-treated human gingival fibroblast-1 (HGF-1) cells. In addition, we utilized gelatin zymography, Western blotting, and reverse transcription-PCR analysis to elucidate the molecular mechanisms underlying MMP-2 inhibition via the mitogen-activated protein kinase (MAPK) and cyclic AMP response element-binding protein (CREB) signaling pathways. Treatment with K. pandurata extract (1-10 μg/ml) dose-dependently suppressed the activity, secretion, and protein expression of MMP-2 in HGF-1 cells exposed to P. gingivalis. At the transcriptional level, inhibition of MMP-2 gene expression by K. pandurata was mediated by phosphorylation of c-Jun N-terminal kinase (JNK) and CREB signaling pathways in P. gingivalis-treated HGF-1 cells. These results suggest that K. pandurata extract suppresses MMP-2 expression at the protein and gene levels via downregulation of the principal JNK and CREB signaling pathways. Due to its efficacy in inhibiting MMP-mediated periodontal destruction, K. pandurata might represent a new, potent periodontal therapy. (J Oral Sci 52, 583-591, 2010)
To assess the diagnostic accuracy of cone beam computed tomography (CBCT) in comparison with conventional radiography for vertical root fractures, 50 of 100 teeth were subjected to vertical root fracture (VRF) and then placed in dry mandibles. 3D scans were obtained for all teeth, and conventional radiographs were used as control images. All the images were assessed by 6 observers, who determined the presence of root fractures by using a 5-point confidence rating scale. The mean area under the curve (Az) for CBCT was 0.91, and that for conventional radiography was 0.64. The difference between the modalities was statistically significant (P = 0.003). On the basis of interclass coefficient, inter-observer agreement for CBCT was 0/750, and that for conventional radiography was 0/637. Thus CBCT was shown to be significantly better than conventional periapical radiography for diagnosis of vertical root fractures in vitro. (J Oral Sci 52, 593-597, 2010)
This study evaluated the effects of the specular component mode of specular component included (SCI) and specular component excluded (SCE), and the grit size of final polishing with SiC paper on color of different types of resin composites and shades. Resin disks of 2 mm in thickness were made with regular, opaque and enamel shades for each of the following: supra-nano spherical filled Estelite Σ Quick (EQ), organic filled hybrid Clearfil Majesty (CM), and S-PRG filled nano-hybrid Beautifil II (B2). One week after curing, the surface roughness and color were measured. Color differences between 3000- and 1000-grit, and between 3000- and 180-grit final polishing groups were calculated. Comparison of L*a*b* between SCI and SCE modes showed that the L* values with SCI were significantly higher than those with SCE in 1000- and 3000-grit groups for EQ and CM, and in 3000-grit group for B2. Comparison of total color differences (ΔE*ab) between SCI and SCE modes for all resin composites and shades in all polishing groups showed that the ΔE*ab with SCE were higher than those with SCI except for opaque shade of EQ with white background in 1000-grit group in which the ΔE*ab values were same. The effect of the specular component mode and polishing on color differed among the resin composites and shades. (J Oral Sci 52, 599-607, 2010)
Calcifying odontogenic cyst (COC) is a developmental odontogenic cyst in the jaw. Because of its diverse histopathologic features and biological behavior, there has long been confusion with regard to its nature as a cyst or neoplasm. This study evaluated the proliferative activity of 57 COC samples, including simple cyst (10 cases), cystic neoplasm (34 cases), solid neoplasm (6 cases) and combined lesion (7 cases) by p53 and PCNA immunohistochemical staining. For assessment of p53 and PCNA positivity, the number of positively stained cells with brown-stained nuclei was counted in 1000 cells from each sample. p53 and PCNA expression in the solid neoplasm subtype were significantly higher when compared to cystic neoplasm and simple cyst (P < 0.05). The lowest p53 and PCNA expression was found in the simple cyst subtype. p53 and PCNA expression in the basal and suprabasal layers was significantly higher in the solid subtype when compared to others, and the difference between COC groups was significant. The results demonstrated that within benign types of COC, the amount of p53 and PCNA in proliferative epithelium is significantly higher when compared to non-proliferative epithelium. p53 and PCNA markers are possible parameters for differentiation of COC subtypes. (J Oral Sci 52, 609-613, 2010)
Periodontal disease is associated with specific periodontal pathogens and may persist as gingivitis or progress to more severe disease. The bacteria involved in disease initiation and progression have not been identified. We used quantitative polymerase chain reaction (PCR) to compare the levels of Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola, and total bacteria detected by different sampling methods. On the basis of the results of clinical examinations, 57 patients were divided into 3 groups: healthy group (group A), gingivitis group (group B), and periodontitis group (group C). Bacterial samples were collected from saliva, mouthwash, and by paper-point sampling of gingival crevicular fluid (GCF), and the samples were analyzed with quantitative PCR targeting 16S rRNA. The numbers of total bacteria in samples of GCF, saliva, and mouthwash were 105 to 106, 108, and 107, respectively, per milliliter. The number of P. gingivalis in GCF samples was lower than 10 in group A; however, in groups B and C, the values were 103 and 104, respectively, indicating that the number of P. gingivalis increased with worsening clinical status. Findings were similar in the samples of saliva and mouthwash. The numbers of T. forsythia showed a pattern similar to that of P. gingivalis in all 3 samples. These results suggest that saliva and mouthwash samples are clinically useful for bacterial testing of periodontal diseases by quantitative PCR. In addition, mouthwash sampling is more feasible and straightforward than saliva sampling. (J Oral Sci 52, 615-621, 2010))
Heat shock proteins (Hsps) 27 and 47 are involved in the control of apoptosis, cell migration, and collagen synthesis. There is some understanding of the immunolocalization of these proteins during the repair process in skin and gastrointestinal mucosa, but their expressions in normal and injured oral mucosa are unknown. The aim of this study was to analyze the immunolocalization and intensity of these proteins in oral ulcers induced in rats and to compare these expression levels with those reported in skin and gastric mucosa. Ulcers were induced on the ventral surface of the tongues of rats. The rats were then euthanized at 0, 24, 48, 72, and 120 h. Hsp27 expression remained low in the first hours of repair, but was higher at 72 h, mainly in the migrating epithelium. Expression of Hsp47 was high at 48 h, mainly in fibroblasts, cells of the vascular wall, and basal keratinocytes of migrating epithelium. In the control group, expressions of these proteins were low, which indicates that these Hsps are constitutive proteins in oral mucosa. Expression levels were similar to those reported in the healing of skin lesions and gastric ulcer, suggesting a common mechanism of Hsp activation in the repair of these tissues. (J Oral Sci 52, 623-631, 2010)
β-Catenin acts as a structural protein at cell-cell adherens junctions and as a transcription activator mediating Wnt signal transduction. Altered β-catenin expression has been associated with loss of cell differentiation and acquisition of an invasive phenotype. In the present study, β-catenin expression was compared immunohistochemically between oral squamous cell carcinoma (30 cases) and verrucous carcinoma (30 cases), and correlated with different histological grades of oral squamous cell carcinoma. Positivity for β-catenin was seen in 17 cases (56.6%) of oral squamous cell carcinoma and 25 cases (83.3%) of verrucous carcinoma, and was significantly correlated with the grade of oral squamous cell carcinoma, whereas no significant correlation of β-catenin expression was observed between oral squamous cell carcinoma and verrucous carcinoma. In oral squamous cell carcinoma, the number of β-catenin-positive cases and the intensity of expression decreased as cancers became more poorly differentiated. Decreased membranous localization and intense cytoplasmic staining were observed in poorly differentiated squamous cell carcinoma. In verrucous carcinoma, β-catenin was demonstrable mainly in the membrane. Down-regulation of β-catenin was significantly correlated with lack of differentiation in oral squamous cell carcinoma. Reduced membranous expression and predominant cytoplasmic localization were prominent among higher-grade tumors, suggesting stabilization of β-catenin and its role as a signaling molecule. Predominant membranous expression in verrucous carcinoma was similar to that observed in well differentiated squamous cell carcinoma, thus corroborating its role in cell adhesion in these subgroups. (J Oral Sci 52, 633-640, 2010)
Legionella pneumophila and Pseudomonas aeruginosa are common colonizers of water environments, particularly dental unit waterlines. The aim of this study was to assess whether the technical, functional and structural characteristics of dental units can influence the presence and the levels of opportunistic pathogens. Overall, 42 water samples were collected from dental units in a teaching hospital in Palermo, Italy, including 21 samples from the 21 taps supplied by the municipal water distribution system and 21 samples from oral rinsing cups at 21 dental units. L. pneumophila was present in 16 out of 21 water samples (76.2%) from dental units, and the median concentration was higher in samples from oral rinsing cups than in those from taps (P < 0.001). P. aeruginosa was equally distributed in water samples collected from oral rinsing cups and from taps. Some characteristics of dental units (age, number of chairs per room, number of patients per day and water temperature) were slightly associated with the presence of P. aeruginosa, but not with contamination by L. pneumophila. Our experience suggests that L. pneumophila is frequently detected in dental units, as reported in previous studies, whereas P. aeruginosa is not a frequent contaminant. As a consequence, microbiological control of water quality should be routinely performed, and should include the detection of opportunistic pathogens when bacterial contamination is expected. (J Oral Sci 52, 641-646, 2010)
The purpose of the present study was to evaluate the effect of cooling rates after firing procedures of veneering porcelain on shear bond strength between veneering porcelain and a zirconium dioxide (zirconia; ZrO2) ceramic material. A total of 48 ZrO2 disks were divided equally into three groups. Two veneering porcelains that are recommended for ZrO2 material – Cerabien ZR (CZR), IPS e.max Ceram (EMX) – and one that is recommended for metal ceramics – Super Porcelain AAA (AAA) were assessed. Each group was then further divided into two subgroups (n = 8) according to cooling time (0 or 4 min) after porcelain firing. Specimens were fabricated by veneering the porcelain on the ZrO2 disks, after which shear bond testing was conducted. Bond strength differed significantly by cooling time in ZrO2-AAA (P < 0.001) and ZrO2-EMX (P = 0.001) specimens. There was no significant difference in shear bond strength with respect to cooling time in ZrO2-CZR specimens (P = 0.382). The duration of cooling from firing temperature to room temperature may affect the shear bond strength of veneering porcelain to a zirconia material depending on porcelain material used. (J Oral Sci 52, 647-652, 2010)
This article describe a rare case of multiple taurodontism involving all molars in a 17-year-old male. Volumetric cone-beam computed tomography was used to investigate internal and external root morphology, including that of a maxillary first molar which required endodontic treatment and retreatment. Medical history was not contributory; however, Klinefelter syndrome was the diagnostic hypothesis in this case. (J Oral Sci 52, 653-658, 2010)
We describe the successful use of a combination of nonsurgical root canal treatment and ultrasonic irrigation for collaborative management of a maxillary left lateral incisor with perforation of the apical third of the root. During the endodontic treatment procedure, the ultrasonically activated tip was used for intracanal irrigation. The area of perforation in the apical third of the root and the main root canal space were obturated with gutta-percha and root canal sealer, using a lateral condensation method. A follow-up clinical and radiographic examination at 5 years after treatment showed an asymptomatic tooth with excellent osseous healing. (J Oral Sci 52, 659-663, 2010)
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