MODELING OF TEMPORAL AND VERTICAL CHANGES IN 137Cs CONCENTRATION IN LAKE ONUMA.

According to the observed data of the activity concentration of $^{137}$Cs in Lake Onuma on Mount. Akagi, located in Gunma Prefecture, the decrease of the activity concentration slowed down since 2 years after the accident of Fukushima Daiichi Nuclear Power Plant. In the present study, we applied the time fractional diffusion equation to reproduce long-term changes in the time series of the activity concentration. In addition, we also reproduced the vertical distribution of the activity concentration with the parameter values, estimated by the time series data. We found that the model fit the observed data well for both time series and vertical distribution.

Long-term prediction of [Formula: see text]Cs in Lake Onuma on Mt. Akagi after the Fukushima accident using fractional diffusion model.

The Fukushima Daiichi Nuclear Power Plant accident also contaminates lakes in Japan. Especially in closed lakes, there is a problem of prolonged low-level [Formula: see text]Cs contamination because the activity concentration of [Formula: see text]Cs declines sharply immediately after the accident, but then begins to decrease slowly. In this paper, we derived a long-term prediction formula based on the fractional diffusion model (FDM) for the temporal variation in [Formula: see text]Cs activity concentrations of the water in Lake Onuma on Mt. Akagi, one of the closed lakes, and of pond smelt (Hypomesus nipponensis), a typical fish species inhabiting in the lake. The formula reproduced well the measured [Formula: see text]Cs activity concentration of the lake water and pond smelt for 5.4 years after the accident. Next, we performed long-term prediction for 10,000 days using this formula and compared it with the prediction results of the two-component decay function model (TDM), which is the most common model. The results suggest that the FDM prediction will lead to a longer period of contamination with low-level [Formula: see text]Cs than the TDM prediction.

Clinical and dental computed tomographic evaluation 1 year after coronectomy.

PURPOSE: Coronectomy is performed when contact between the mandibular third molar apex and the inferior alveolar nerve is suspected. The efficacy of coronectomy compared with conventional tooth extraction has been recognized in recent years. However, few studies have reported the postoperative prognosis of roots remaining in the bone or surrounding tissue. Therefore, a clinical evaluation was performed with dental computed tomographic imaging of the coronectomy sites 1 year after the procedure. PATIENTS AND METHODS: This study investigated 101 patients (116 teeth) who underwent a coronectomy from March 2006 through December 2009. They were recalled 1 year later for a clinical evaluation and dental computed tomographic imaging of the coronectomy sites. The clinical evaluation was based on palpation and macroscopic findings. RESULTS: In 99.2% (115 teeth) of the studied cases, the soft tissue distal to the mandibular second molar was healthy and the retained roots were covered by bone. In 1 case (0.8%), an eruption of roots into the oral cavity was observed; however, no inflammation was observed in the nearby soft tissue. In all 116 teeth, no transmission images indicative of periapical lesions, which usually result from necrosis of the pulp, were observed in the apical area of the retained roots. CONCLUSIONS: The absence of transmission images indicative of periapical lesions and the presence of bone covering more than 99.2% (115 teeth) of the retained roots showed a safe postoperative course at the 1-year follow-up after coronectomy.

Enterococcus faecium WB2000 Inhibits Biofilm Formation by Oral Cariogenic Streptococci.

This study investigated the inhibitory effect of probiotic Enterococcus faecium WB2000 on biofilm formation by cariogenic streptococci. The ability of E. faecium WB2000 and JCM5804 and Enterococcus faecalis JCM5803 to inhibit biofilm formation by seven laboratory oral streptococcal strains and 13 clinical mutans streptococcal strains was assayed. The Enterococcal strains inhibited biofilm formation in dual cultures with the mutans streptococcal strains Streptococcus mutans Xc and Streptococcus sobrinus JCM5176 (P < 0.05), but not with the noncariogenic streptococcal strains. Enterococcus faecium WB2000 inhibited biofilm formation by 90.0% (9/10) of the clinical S. mutans strains and 100% (3/3) of the clinical S. sobrinus strains. After culturing, the pH did not differ between single and dual cultures. The viable counts of floating mutans streptococci were lower in dual cultures with E. faecium WB2000 than in single cultures. Enterococcus faecium WB2000 acted as a probiotic bacterial inhibitor of cariogenic streptococcal biofilm formation.

Association between oral malodour and psychological characteristics in subjects with neurotic tendencies complaining of halitosis.

OBJECTIVE: To assess the psychosomatically subjective symptoms of subjects with neurotic tendencies complaining of halitosis. DESIGN: Breath malodour was measured in 368 patients using organoleptic test and gas chromatography. Neurotic tendency and subjective symptoms were assessed using the Cornell Medical Index (CMI). RESULTS: Of the 79 subjects who met the criteria for neurotic tendencies according to CMI scores, 58 (73.4%) had oral malodour, whereas 21 (26.6%) did not. Coated tongue, periodontal pocket, and daily drinking were significantly more common in subjects with oral malodour. On the CMI questionnaire, subjects with no oral malodour more frequently responded 'yes' to questions about fatigue and psychological problems in their families. Additionally, many answered that they had perceived their own bad breath. CONCLUSIONS: Difficulties experienced by subjects with neurotic tendencies and oral malodour may manifest primarily in oral conditions, whereas those experienced by individuals with neurotic tendencies and no oral malodour may manifest primarily in psychosomatic symptoms.

Effects of postoperative radiotherapy for temporomandibular joint ankylosis after gap arthroplasty: an animal study using sheep.

PURPOSE: The aim of the present study was to examine the effects of postoperative irradiation on reducing heterotopic bone formation after gap arthroplasty release of temporomandibular joint ankylosis. MATERIALS AND METHODS: Five sheep underwent induction of right temporomandibular joint ankylosis. After 3 months, the ankylosis was released by gap arthroplasty. At 24 hours after the release, they received a single radiation dose of 10 Gy. All sheep were sacrificed at 3 months after gap arthroplasty release. The body weight, jaw opening amount, and radiographs were measured at key intervals, with histologic assessment after death. The findings were compared with those in a control group treated with gap arthroplasty without irradiation. RESULTS: The clinical measurements, radiographs, and histologic findings all revealed less evidence of reankylosis in the irradiated sheep. CONCLUSION: The results of the present study have shown that a single radiation dose at 24 hours after gap arthroplasty for temporomandibular joint ankylosis inhibits heterotopic ossification.

Clinical evaluations of coronectomy (intentional partial odontectomy) for mandibular third molars using dental computed tomography: a case-control study.

PURPOSE: Studies have suggested that coronectomy reduces the risk of inferior alveolar nerve injury (IANI) when a close relationship with the inferior alveolar canal is indicated on panoramic imaging. However, the relationship between the inferior alveolar canal and the root are unclear on panoramic imaging. Our aim was to compare coronectomy with traditional extraction for the treatment of mandibular third molars that had clear high IANI risks as evaluated by dental computed tomography. PATIENTS AND METHODS: We designed a case-control study of subjects with high-risk signs of IANI on panoramic images evaluated by dental computed tomography before enrollment. The 220 patients enrolled were assigned to extraction (control group, n = 118) or coronectomy (case group, n = 102). RESULTS: The mean follow-up time was 13 months in the extraction group and 13.5 months in the coronectomy group. Six IANIs (5%) were found in the extraction group. In the coronectomy group, 1 patient (1%) had symptoms of neurapraxia, which disappeared within 1 month. Four remaining roots had signs of postoperative infection, and the patients underwent extraction of the root. No nerve damage resulted in these patients after repeat extraction. CONCLUSIONS: Coronectomy might reduce the risk of nerve injury for patients at true high risk of IANI as evaluated by dental computed tomography. A long-term postoperative review is needed to assess the incidence of root migration and the root extraction and infection rates after coronectomy.

A Case Report of Tooth Wear Associated with a Patient's Inappropriate Efforts to Reduce Oral Malodor Caused by Endodontic Lesion.

Here, we report a case of severe tooth wear associated with a patient's inappropriate efforts to reduce oral malodor. A 72-year-old male patient visited our breath clinic complaining of strong breath odor. Former dentists had performed periodontal treatments including scaling and root planing, but his oral malodor did not decrease. His own subsequent breath odor-reducing efforts included daily use of lemons and vinegar to reduce or mask the odor, eating and chewing hard foods to clean his teeth, and extensive tooth brushing with a hard-bristled toothbrush. Oral malodor was detected in our breath clinic by several tests, including an organoleptic test, portable sulphide monitor, and gas chromatography. Although patient's oral hygiene and periodontal condition were not poor on presentation, his teeth showed heavy wear and hypersensitiving with an unfitted restoration on tooth 16. Radiographic examination of the tooth did not reveal endodontic lesion, but when the metal crown was removed, severe pus discharge and strong malodor were observed. When this was treated, his breath odor was improved. After dental treatment and oral hygiene instruction, no further tooth wear was observed; he was not concerned about breath odor thereafter.