A complex aggregation of microorganisms growing on a solid substrate is termed a biofilm and is considered to be an etiological agents. Pseudomonas aeruginosa and Streptococcus mutans are representative bacteria in such biofilms. It is well known that deuterium oxide (D₂O) causes toxic effects on a number of biological systems. We investigated the effects of D₂O on growth and biofilm formation of P. aeruginosa and S. mutans. These bacteria were incubated in medium containing D₂O (100%, 75% or 0%) at 37°C for 24hr, 48hr or 72hr. Growth of P. aeruginosa was inhibited by D₂O within the first 48hr. However, after 72hr, growth rate was seen to increase in the D₂O-containing medium compared with in medium without D₂O. In contrast, the growth of S. mutans in the D₂O medium was inhibited within 72hr. The biofilm formation of P. aeruginosa was increased in the D₂O medium. Biofilm formation of S. mutans in the D₂O medium increased compared with in the medium without D₂O, but this increase was only temporary in the case of P. aeruginosa. Compared to biofilm formation in 0% D₂O medium marked as 100%, the biofilm formation rate of S. mutans in 75% D₂O medium was 143% at 24hr, 146% at 48hr and 130% at 72hr. In other D₂O concentration media biofilm formation was lower. In 100% D₂O medium, biofilm formation rate decreased from 114% at 24hr to 56% at 72hr. The biofilm formation rate of P. aeruginosa in 100% D₂O medium was 172% at 24hr, but decreased to 88% at 72hr. Biofilm formation of P. aeruginosa in 75% and 0% D₂O media showed no significant difference. We consider that these results were due to stress or alteration in bacterial metabolisms.

抄録全体を表示

The bactericidal effects of lasers with wavelengths of 1.67 and 2.94μm on cariogenic Streptococcus mutans were investigated. Temperature during irradiation was also measured to determine the mechanism underlying the bactericidal effects of the lasers. An aliquot of 2μl cell suspension of S. mutans JC-2 strain was placed on anhydrous quartz or dentin plate, covering an area of approximately 5.0 mm in diameter to a depth of approximately 0.1 mm. Cell suspension was then irradiated at a power of 0.8 W (3.1 J/cm²) at a rate of 40 pps for 30 sec. After irradiation, the plate was put into a bottle containing PBS and vigorously voltated. Solution was serially diluted and inoculated on MS agar. After incubation anaerobically for 72 hr, colony forming units on the agar were counted. The experimental group, the number of bacteria decreased significantly compared to the control group under all conditions. No significant differences were observed in effect of wavelength or plate on bactericidal activity. In conclusion, laser irradiation at a wavelength of 1.67μm for 30 sec showed a bactericidal effect on S. mutans, suggesting that this wavelength is more useful than 2.94μm due to greater tissue penetration.

抄録全体を表示

To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, p<0.005), calcium and magnesium concentrations (r=0.61, p<0.005), Ca/Mg and calcium concentrations (r=0.64, p<0.005), and sulfuric ion and magnesium concentrations (r=0.55, p<0.005). Negative correlations were found between sulfuric ion concentrations and pH levels (r=-0.31, p<0.01), and magnesium concentrations and pH levels (r=-0.32, p<0.01). This suggests that mouth rinse from employees working with sulfuric acid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure.

抄録全体を表示

The treatment of Miller class III gingival recession is considered a challenge in periodontal practice, and among the different techniques used, autogenous connective tissue graft has shown the most favorable results. In some cases, more than one procedure may be necessary. In this case report, we describe the simultaneous application of a combination of three techniques (the tunnel technique, a connective tissue graft and a laterally positioned flap) to treat a Miller class III gingival recession localized in the lower anterior region. Twelve months after surgical procedures, partial root coverage, favorable esthetic results and a gain in clinical attachment level were observed, with no periodontal pockets or bleeding on probing.

抄録全体を表示

Aberrant ectodermal tissues during the fetal period or acquired aberrant epithelial tissue due to trauma or surgery are thought to cause dermoid and epidermoid cysts. Their incidence is 7.0% in the head and neck region and only 1.6% in the oral cavity, where they mostly present in the floor of the mouth. On the other hand, they are extremely rare in the soft palate and uvula, and only six cases have been reported. Epidermoid cysts grow slowly and asymptomatically, and thus rarely cause oral dysfunction. However, cysts arising in the floor of the mouth can lead to developmental disorders due to impaired suckling and swallowing. This report describes a 4-week-old boy in whom an epidermoid cyst developed in the midline region of the soft palate close to the uvula. Decreased suckling ability led to a poor in body weight, so resection was performed at an early age. The histopathological diagnosis was epidermoid cyst.

抄録全体を表示

Core carrier techniques are unique among the various root canal filling techniques for delivering and compacting gutta-percha in the prepared root canal system. Thermafil (TF), considered the major core carrier device, is provided as an obturator consisting of a master core coated with thermoplasticized gutta-percha. We have devised a thermoplasticized gutta-percha filling technique using a polypropylene core, FlexPoint^® NEO (FP), which was developed as a canal filling material that can be sterilized in an autoclave. Therefore, FP can be coated onto thermoplasticized gutta-percha and inserted into the prepared canal as a core carrier. The FP core carrier technique offers many advantages over the TF system: the core can be tested in the root canal and verified radiographically; the core can be adjusted to fit and surplus material easily removed; furthermore the core can be easily removed for retreatment. The clinical procedure of the FP core carrier technique is simple, and similar that with the TF system. Thermoplasticized gutta-percha in a syringe is heated in an oven and extruded onto the FP core carrier after a trial insertion. The FP core carrier is inserted into the root canal to the working length. Excess FP is then removed with a red-hot plastic instrument at the orifice of the root canal. The FP core carrier technique incorporates the clinical advantages of the existing TF system while minimizing the disadvantages. Hence the FP core carrier technique is very useful in clinical practice. This paper describes the FP core carrier technique as a new core based method.

抄録全体を表示

The biologically active form of vitamin D, 1α,25-dihydroxy vitamin D₃ (VD), regulates the synthesis of the bone Ca-binding proteins osteocalcin and osteopontin. The actions of VD are mediated through the vitamin D receptor (VDR). Liganded VDR heterodimerizes with the retinoid X receptor and interacts with a vitamin D response element (VDRE). Recently, it has been demonstrated that vitamin D responses elicited in osteoblasts can be rapid as well as long-term. The purpose of this study was to elucidate the mechanism of Ca²⁺ signaling of VD in osteoblasts using intracellular Ca²⁺ ([Ca²⁺]_i) measurements. A rapid VD (10 nM)-induced increase in [Ca²⁺]_i was observed within 40sec. This increase, however, was negated with application of Ca²⁺-free Krebs' solution. These results indicate that VD induces an increase in [Ca²⁺]_i from extracellular Ca²⁺ in osteoblasts.

抄録全体を表示