Perspectives on a new educational system for dental hygiene students in Japan

The purpose of this article is to report changes to dental hygiene education in Japan and to evaluate the successful implementation of these changes in 2010. The legislative change that began in 2005 revised the length of education for dental hygiene students from two years to three or four years (the mandate was three years), which has led to a dramatic change in program curriculum. After a five-year moratorium, a new curriculum has been established for dental hygiene education in Japan. The new curriculum provides students the requisite knowledge to effectively perform the latest dental hygiene procedures. Although the change of the educational system from the present mandatory three-year to the new four-year programs poses many administrative problems, we believe this shift will ultimately provide a more thorough and in-depth education for students.     

Chemical composition and immunobiological properties of lipopolysaccharide and lipid-associated proteoglycan from Actinobacillus actinomycetemcomitans

Lipopolysaccharide (LPS) and lipid-associated proteoglycan (LPG) were isolated from Actinobacillus actinomycetemcomitans ATCC 29523 by the phenol-water and butanol-water procedures. The LPS was composed of 41 % neutral sugar. 8% hexosamine, 31 % fatty acid, 2% protein, and 2% phosphorus, while the butanol-water-extracted LPG was composed of 13% neutral sugar, 2% hexosamine, 14% fatty acid. 56% protein, and 1% phosphorus. The major fatty acids of LPS and LPG were β-hydroxymyristic, myristic, and palmitic acids. These preparations induced mitogenic and polyclonal responses of LPS-responsive C3H/HeN mouse spleen cells and enhanced in vitro immune responses of the spleen cells to sheep erythrocytes. Spleen cells of C3H/HeJ mouse that were nonresponsive to enterobacteriaceal LPS responded to the butanol-water-extracted LPG, but not to the phenol-water-extracted LPS. The Limulus amebocyte lysate clotting activity of A. actinomycetemcomitans LPS was comparable to that of Escherichia coli K235 LPS. These results indicate that A. actinomycetemcomitans LPS is biologically and immunochemically of Enterobacteriaceae type.     

Cytokine secretion of periodontal ligament fibroblasts derived from human deciduous teeth: effect of mechanical stress on the secretion of transforming growth factor-beta 1 and macrophage colony stimulating factor

The periodontal ligament may play an important role in tooth eruption, root development and resorption. The tissue physiologically receives mechanical force during mastication. We focused on the effects of intermittent mechanical strain on the cytokine synthesis of periodontal ligament (PDL) fibroblasts in vitro. The cells were derived from human periodontal ligament of deciduous teeth (HPLF-Y) and permanent teeth (HPLF). The two kinds of PDL cells and human gingival fibroblasts (HGF) were cultured in flexible bottomed culture plates. The cells were mechanically stretched at 5% elongation, 3-cycles/min for 24 h on d 7 in culture using a Flexercell strain unit. After the stretching, we measured DNA content and alkaline phosphatase activity in the cell layer, transforming growth factor beta 1 (TGF-beta 1) and macrophage colony stimulating factor (M-CSF) contents in the conditioned medium. The TGF-beta 1 level in the conditioned medium of HPLF was significantly higher than that of HPLF-Y and HGF. It was stimulated by mechanical stretching only on HPLF, whereas no significant effect was observed on HPLF-Y and HGF. M-CSF secretion was inhibited by the stretching on all of HPLF, HPLF-Y and HGF. 1 alpha, 25 dihydroxy vitamin D3 (D3) stimulated M-CSF secretion into the culture medium of both HPLF and HPLF-Y, but the stretching inhibited M-CSF secretion and completely blocked the enhancement by D3. These data suggest that periodontal ligament cells synthesize and secrete the molecules as autocrine or paracrine factors that affect bone remodelling and root resorption and the level of those factors change in response to mechanical stress.     

Extracellular proteinaceous substances from Haemophilus actinomycetemcomitans induce mitogenic responses in murine lymphocytes

An extracellular proteinaceous substance (ES) and lipopolysaccharide (LPS) were prepared from culture supernatants and whole cells of Haemophilus actinomycetemcomitans Y4, respectively. In addition, extracellular LPS (E-LPS) was isolated from the ES preparation by the phenol-water procedure. Both the ES and LPS induced Limulus amebocyte lysate clotting and the local Shwartzman reaction. LPS and E-LPS from the strain were mitogenic for BALB/c, BALB/c (nu/nu) and C3H/HeN mouse spleen cells, but not for C3H/HeJ spleen cells and BALB/c thymocytes. On the other hand, ES was also mitogenic for C3H/HeJ spleen cells. Polymyxin B suppressed to a lesser extent the mitogenicity of ES than that of LPS and E-LPS. The mitogenicity of ES was markedly inhibited by pronase treatment. These results suggest that H. actinomycetemcomitans produces extracellularly proteinaceous mitogenic substances as well as LPS.     

Role of interleukin-1 and prostaglandin in in vitro bone resorption induced by Actinobacillus actinomycetemcomitans lipopolysaccharide

Lipopolysaccharide (Y4 LPS) isolated from Actinobacillus actinomycetemcomitans strain Y4 induced bone resorption in BALB/c mouse calvaria organ culture. The calcium release from LPS-low responsive C3H/HeJ mouse calvaria by Y4 LPS was very low. Indomethacin almost completely inhibited prostaglandin E₂ (PGE₂) production by Y4 LPS-stimulated BALB/c mouse calvaria, but did not suppress interleukin-1 (IL-1) release from the calvaria, and partially suppressed the bone resorption. Dexamethasone strongly inhibited the PGE₂ and IL-1 production by Y4 LPS-stimulated BALB/c mouse calvaria. as well as Y4 LPS-induced bone resorption. Dexamethasone inhibited expression of membrane IL-1 on osteoblastic cells stimulated with Y4 LPS, but indomethacin did not. Furthermore, anti-IL-1 serum partially suppressed the calcium release from Y4 LPS-stimulated BALB/c mouse calvaria. These results suggest that both PGE₂ and IL-1 participate in Y4 LPS-induced bone resorption in vitro .     

Pediatric acute lymphocytic leukemia with osseous changes in jaws: Literature review and report of a case

A case of acute lymphocytic leukemia (ALL) in a child is presented. We also reviewed the recent literature of similar cases describing leukemic jaw bones involvement in Japan. Radiographic examinations of the patient disclosed diffuse osteolytic changes of the entire jaws, the corticated border of the crypts of developing teeth, loss of lamina dura, a thickened periodontal space and disappearance of the radiopaque lines that delineate the borders of the mandibular canal. Pronounced regression and restoration of the alveolar bone and the crypts were detectable on the radiographs taken after a course of the treatment for ALL. An apparent radiographic change of jaw bone after the treatment indicates that the radiographic examinations of children with leukemia in the leukemic process are of quite diagnostic value.     

Occult Risk of Broken Instruments for Endoscopy-assisted Surgery

Background

The influence of broken sophisticated surgical instruments on the safety of surgery has yet to be determined, in spite of an assumption that breakage of surgical instruments is not associated with critical incidents. The purpose of the present study was to delineate the risk from breakage of surgical instruments used in surgery assisted by endoscopy.

Methods

A retrospective analysis was conducted to determine the frequency of breakage of instruments used in 39,817 operations from 2007 to 2011. Data of breakage were collected using incident/near-incident reports and the request forms for repair of broken instruments.

Results

During the study period, 441 instruments were reported to be broken intraoperatively, and 7,541 were found to be broken on inspection. The incidence of breakage adjusted by the number of operations and the number of uses suggested that instruments for endoscopy-assisted surgery are broken more frequently intraoperatively than are any other type of instruments (visceral surgery: 0.039 versus 0.017, P = 0.0002, RR = 2.318; obstetrics/gynecology: 0.023 versus 0.0067, P < 0.0001, RR = 3.461; thoracic surgery: 0.019 versus 0.004, P = 0.0772, RR = 5.212). Inappropriate use and wearing out were two major possible causes of breakage of instruments. The predominant adverse events were suggested to be attributable to parts falling off broken instruments because of inappropriate use.

Conclusions

Our results demonstrated that surgery assisted by endoscopy has its own occult risk, which has not been previously highlighted. Minimally invasive surgery is not necessarily safe with respect to breakage of surgical instruments. Our data provide substantial evidence for higher risk of instrument breakage in endoscopy-assisted surgery, as well as its possible detrimental effect on patient safety.