[Weighted-averaging multi-planar reconstruction method for multi-detector row computed tomography].

Development of multi-detector row computed tomography (MDCT) has enabled three-dimensions (3D) scanning with minute voxels. Minute voxels improve spatial resolution of CT images. At the same time, however, they increase image noise. Multi-planar reconstruction (MPR) is one of effective 3D-image processing techniques. The conventional MPR technique can adjust slice thickness of MPR images. When a thick slice is used, the image noise is decreased. In this case, however, spatial resolution is deteriorated. In order to deal with this trade-off problem, we have developed the weighted-averaging multi-planar reconstruction (W-MPR) technique to control the balance between the spatial resolution and noise. The weighted-average is determined by the Gaussian-type weighting function. In this study, we compared the performance of W-MPR with that of conventional simple-addition-averaging MPR. As a result, we could confirm that W-MPR can decrease the image noise without significant deterioration of spatial resolution. W-MPR can adjust freely the weight for each slice by changing the shape of the weighting function. Therefore, W-MPR can allow us to select a proper balance of spatial resolution and noise and at the same time produce suitable MPR images for observation of targeted anatomical structures.

Automatic segmentation of teeth from dentomaxillofacial 3D-CT images.

CT is an effective tool for image diagnosis because it enables noninvasive observation of internal organs. In the course of CT, 3D-CT, such as a helical scanning CT and a multi-detector row CT, has been developed. With the use of 3D-CT, organs can be observed from several viewing directions. Even now, however, 3D-CT images are generated by manual procedures to extract objective organs using the threshold method. These procedures waste time and effort. Therefore, development of highly automated and effective extracting techniques has been desired. The region growing (RG) method is one of the effective techniques of extracting internal organs. The conventional RG method, however, has some defects. Extracted regions are strongly affected by the threshold value for segmentation. A break point on a region contour yields a leakage of region. To overcome these defects, we formulated a modified region growing method with edge detection (MRGWED) which combines a three-dimensional region growing technique and an edge detection technique. Using the MRGWED, we tried to extract teeth from dentomaxillofacial 3D-CT image data.

Antimicrobial activity of super-oxidised water against oral microorganisms.

OBJECTIVE: The radical anion of oxygen (O(-)) is extremely oxidative and shows high reactivity. In this study, the antibacterial activity of water super-oxidised water containing high concentration of O(-) (O(-)-water) was tested against cultured planktonic cells of cariogenic bacteria, periodontopathic bacteria and Candida albicans. METHODS: O(-)-water was prepared using the AOE-750 (Oxy Japan Corporation, Japan) and its antibacterial activity against pure culture of Streptococcus sobrinus, Porphyromonas gingivalis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and C. albicans evaluated. Each oral microorganism (10(4) to 10(8)CFU/ml) was exposed to three concentrations of O(-)-water at room temperature or 37 degrees C for 15s to 24h. RESULTS: Exposure to O(-)-water resulted in a bactericidal effect against all cariogenic and periodontopathic bacteria tested. No significant fungicidal effect was observed on C. albicans, however. CONCLUSION: The results demonstrate that O(-)-water exerts an antibacterial effect on cariogenic and periodontopathic bacteria.

Adenomatoid odontogenic tumor arising from the mandibular molar region: a case report and review of the literature.

This case report describes a rare case of an adenomatoid odontogenic tumor (AOT) arising in the mandibular third molar region of a 20-year-old female. The tumor was a well-circumscribed intraosseous lesion with an embedded tooth. Histologically, the induction of extensive globular calcification was evident in addition to the characteristic histological features of AOT. The present case lends support to the categorization of AOT as an odontogenic tumor consisting of a disorderly mixture of odontogenic epithelium and odontogenic ectomesenchyme with calcification.

Genetic aberration on chromosome 10 in human oral squamous cell carcinoma.

Recently a tumor suppressor gene, a deleted in malignant brain tumor gene (DMBT1), was detected on chromosome 10. In some types of tumors, the frequent deletion of DMBT1 locus have been reported as well as loss of heterozygosity (LOH) on chromosome 10. However, little is known relating to human oral squamous cell carcinoma (OSCC). To study the genetic aberrations on chromosome 10 in OSCC, we performed polymerase chain reaction (PCR) analysis of microsatellite polymorphisms corresponding to 16 loci, containing 2 DMBT1 loci. We examined 38 oral primary squamous cell carcinoma (SCC) tissues and corresponding normal tissues. Microsatellite instability (MI) was detected at least on 1 of the 16 loci in 15 (39.5%) of 38 cases, and loss of heterozygosity (LOH) at least 1 of the 16 loci was also observed in 28 (73.7%) of 38 cases. LOH was accumulated at D10S202 (34.6%) and D10S217 (28.6%), suggesting the presence of two putative tumor suppressor genes associated with OSCC. The 2 DMBT1 loci, D10S209 and D10S587, had comparatively high frequent LOH (20.0 and 22.7%, respectively), maybe indicating the important role of DMBT1 in OSCC. No significant correlation between histological differentiation and LOH was found. These results suggest that genetic aberrations on chromosome 10 play important roles in the oncogenesis of OSCC.