Streptococcus troglodytae sp. nov., from the chimpanzee oral cavity.

Six strains, TKU 25, TKU 28, TKU 30, TKU 31(T), TKU 33 and TKU 34, were isolated from the oral cavity of a chimpanzee (Pan troglodytes). Colonies of strains grown on Mitis-Salivarius agar were similar in morphology to that of Streptococcus mutans. The novel strains were Gram-stain-positive, facultatively anaerobic cocci that lacked catalase activity. Analysis of the partial 16S rRNA gene sequences of these isolates showed that the most closely related strain was the type strain of S. mutans (96.4 %). The next closely related strains to the isolates were the type strains of Streptococcus devriesei (94.5 %) and Streptococcus downei (93.9 %). These isolates could be distinguished from S. mutans by inulin fermentation and alkaline phosphatase activity (API ZYM system). The peptidoglycan type of the novel isolates was Glu-Lys-Ala(3). Strains were not susceptible to bacitracin. On the basis of phenotypic characterization, partial 16S rRNA gene and two housekeeping gene (groEL and sodA) sequence data, we propose a novel taxon, Streptococcus troglodytae sp. nov.; the type strain is TKU 31(T) ( = JCM 18038(T) = DSM 25324(T)).

Microtensile bond strength of self-adhesive luting cements to ceramics.

The purpose of this paper was to compare the bond strengths of the self-adhesive luting cements between ceramics and resin cores and examine their relation to the cement thickness. Three self-adhesive luting cements (Smartcem, Maxcem, and G-CEM) and a resin cement (Panavia F 2.0) for control were used in the paper. The thickness of the cements was controlled in approximately 25, 50, 100, or 200 µm. Each 10 specimens were made according to the manufacturers' instructions and stored in water at 37°C. After 24 hours, microtensile bond strength (µTBS) was measured. There were significant differences in cements. Three self-adhesive cements showed significantly lower µTBSs than control that required both etching and priming before cementation (Tukey, P < 0.05). The cement thickness of 50 or 100 µm tended to induce the highest µTBSs for each self-adhesive luting cements though no difference was found.

XPS analysis of the dentin irradiated by Er: YAG laser.

The aim of this study was to investigate the effect of Er:YAG laser irradiation on human dentin surface using X-ray photoelectron spectroscopy (XPS). 10 human dentin disks were prepared from extracted human molars for XPS analysis. These specimens were divided into two groups of five: a control group and group that were irradiated by an Er:YAG laser beam (100 mJ, 1Hz). All specimens were analyzed by XPS over a wide scanning range and narrow scanning ranges. The Ca/P ratio was calculated from the XPS results. In the results, the binding energies of Ca, P, and N in the laser-irradiated group were higher than those in the control group. The Ca/P ratio of the Er:YAG laser irradiated group (1.24+/-0.05) was significantly lower than that of the control group (1.52+/-0.16). This study showed that Er:YAG laser irradiation decreased Ca/P ratio and denatured the collagen of human dentin.

Short- and long-term in vitro study of the bonding of eight commercial adhesives to normal and deproteinized dentin.

OBJECTIVE: The aims of this study were to investigate the influence of deproteinization of dentin on the shear bond strength (SBS) mediated by eight dentin adhesives, and to evaluate the long-term durability of the SBSs. The hypotheses were that deproteinization of dentin would not affect the capacity for adherence, and that in contrast to the SBSs to collagen-rich surfaces, the SBSs to deproteinized surfaces would be stable during a 1-year period of storage in water. MATERIAL AND METHODS: Ground surfaces of human dentin were either rinsed with water (normal dentin) or treated with sodium hypochlorite (deproteinized dentin). The dentin surfaces were analyzed by Fourier transform-infrared spectroscopy (FT-IR) using horizontal attenuated total reflectance (HATR). In addition, the SBS to normal and deproteinized dentin treated with the adhesives was measured after 24 h or 1 year of storage in water. RESULTS: The IR absorption peaks at approximately 1,640, 1,560, and 1,240 cm(-1) were assigned to the collagen matrix and peaks at about 1,000 cm(-1) were assigned to the phosphate group in hydroxyapatite. From the relative magnitude of the peaks, it was determined that the utilized deproteinization method was effective. Furthermore, the normal dentin group showed SBS values ranging from 10 to 39 MPa and the deproteinized dentin group showed SBS values ranging from 13 to 30 MPa. CONCLUSIONS: According to the statistical analysis, the results only partly supported the hypotheses: it was found that the influence on bond strength of deproteinization of dentin surfaces and the effect of 1 year of storage in water depended on the composition of the dentin adhesive.

Reduced irradiation time in slow-curing of resin composite using an intensity-changeable light source.

Possibility to shorten the total irradiation time in slow-curing with an intensity-changeable light source, Curetron 7 (CT-7), was investigated for four hybrid-type resin composites. Irradiation condition with CT-7 was assigned as 10 or 20 seconds at low light intensity (230 mW/cm2) and followed by 20 or 10 seconds at high intensity (600 mW/cm2) respectively (i.e., a total of 30 seconds). For a reference, irradiation was carried out for 30 seconds using a halogen lamp (900 mW/cm2). After irradiation, mechanical properties of the cured composites--in terms of microhardness and flexural strength--were evaluated. Also, cavity adaptation was examined in standardized, cylindrical dentin cavities treated with an adhesive system. Compared to the reference irradiation, slow-curing with CT-7 produced acceptable mechanical properties and better adaptation. These results suggested that total exposure time of slow-curing with CT-7 could be shortened to 30 seconds.

In vitro sealing performance of two one-step adhesive systems in cervical cavities.

PURPOSE: To evaluate the effects of 1) wall grinding status, 2) thermal stress, and 3) time of polishing on sealing performance of two one-step bonding systems in cervical cavities. MATERIALS AND METHODS: Semicircular cavities with dimensions of 3 x 3 x 1.5 mm were prepared along the CEJ of extracted human premolars. In experiment 1, the cavity walls were additionally ground with round steel diamond burs (regularly ground) or finished with superfine diamond burs. The cavities were treated with AQ Bond (AQ) or One-up Bond F (OB) and filled with a resin composite. Then thermocycling (5 degrees C to 55 degrees C, 1000 x) was performed. In experiment 2, the regularly ground cavities were used. After restoration, the teeth were subjected to thermocycling (1,000 to 5,000 x). In experiment 3, the restorations in the regularly ground cavities were polished immediately or 24 h after filling. No thermocycling was carried out in this group. All specimens were immersed in a dye solution for 2 h. Microleakage at coronal and apical walls was evaluated on the longitudinal sections of the restorations. RESULTS: For OB, the cavities finished with superfine burs exhibited more microleakage at the coronal wall than the regularly ground cavity (p < 0.05). The leakage at the coronal walls increased with the number of thermal cycles for both systems (p < 0.05). The delayed polishing generated better adaptation at the apical wall of AQ and at the coronal wall of OB (p < 0.05). CONCLUSION: Grinding status, thermocycling, and time of polishing had influences on the sealing performance of the two one-step adhesive systems.

Comparison of bonding efficacy of an all-in-one adhesive with a self-etching primer system.

The aim of this study was to compare the bonding efficacy of an all-in-one adhesive with that of a self-etching primer system by measuring microleakage after thermocycling and the microtensile bond strength (microTBS) to enamel and dentin. Circular class V cavities along cement-enamel junctions were prepared in 20 extracted human premolars. Each 10 teeth were bonded with either AD Bond (AD) or Clearfil SE Bond (SE), and filled with a resin composite (Charisma). After thermocycling and staining with 0.5% basic fuchsin, the microleakage at the coronal and apical walls was evaluated using longitudinal sections. In addition 20 premolars were used to measure microTBS at 24 h after bonding for these adhesives to enamel and dentin that corresponded to the coronal and apical walls of the class V cavities. AD showed more microleakage than SE in the coronal walls, but there was less microleakage in the apical walls and no difference in apical leakage between the two adhesives. microTBS (SD) in MPa to enamel and dentin were 25.2 (7.3) and 68.3 (9.4) for AD, and 35.8 (7.4) and 76.4 (7.8) for SE, respectively. AD gave a lower microTBS to enamel than did SE. The results suggested that the poor adaptation at the coronal wall in AD might be caused by the lower bond strength to enamel.

Effect of slow-curing on cavity wall adaptation using a new intensity-changeable light source.

OBJECTIVE: The purpose of the study was to investigate the effects of a new intensity-changeable light source Curetron 7 (CT-7) devised for the slow-curing on cavity wall adaptation in the adhesive composite restorations, as well as the microhardness of the cured composite. METHODS: Microhardness of both top and bottom surfaces was measured by an indentation method for 2mm thick cylindrical specimens, and cavity adaptation was evaluated in cylindrical dentin cavities (slashed circle 3.5x1.5mm(2)) of human extracted molars bonded to a hybrid resin composite. The irradiation was done with CT-7, VIP or Candelux (CDX) under the following five conditions: CT1, 600mW/cm(2)x30s (CT-7); CT2, 230mW/cm(2)x20s+600mW/cm(2)x20s (CT-7); CT3, 230mW/cm(2)x20s+pause x 10s+600mW/cm(2)x20s (CT-7); VIP, 300mW/cm(2)x3s+pause x 3min+600mW/cm(2)x30s (VIP); CDX, 200mW/cm(2)x10s+600mW/cm(2)x30s. RESULTS: Five irradiation conditions had no influence on the microhardness for either top or bottom surface (Scheffe, p>0.05). In conditions CT3, VIP and CDX, top surfaces were harder than bottom surfaces (Student's t-test, p<0.05). The statistical analysis revealed no difference in adaptation among the locations along the cavity walls for each irradiation conditions (Kruskal-Wallis, p>0.05). In comparison of poled data for each condition, the best adaptation was seen in condition CT3, and the second in condition VIP (Kruskal-Wallis, p<0.05). SIGNIFICANCE: These results proved the efficacy of the slow-curing method combined with the interval between two irradiations with low intensity and high intensity. CT-7 could be useful for the adhesive composite restorations.