Yasunori Sumi

Stability of voxel values from cone‐beam computed tomography for dental use in evaluating bone mineral content

OBJECTIVESnThe objective of this study was to investigate the stability of voxel values from cone-beam CT (CBCT) using a flat panel detector in changing surrounding circumstances mimicking clinical situations.nnnMATERIALS AND METHODSnSeven hydroxyapatite (HA) rods (0, 40, 80, 120, 160, 199, and 239xa0mgxa0Ca/cm(3) ) were set in a 16xa0cm diameter water phantom and scanned with CBCT (FineCube) and also with multislice CT (MSCT) used as reference. The voxel values from CBCT were measured by the obtained images with OsiriX software (http://www.osirix-viewer.com), and compared with the CT numbers from MSCT. We examined the correlation between the voxel values and the HA contents, the variance of voxel values, and the influence of changing surrounding circumstances on the voxel values.nnnRESULTSnThe voxel values from CBCT were different from the CT numbers from MSCT, but there was a linear Pearson correlation between the voxel values and the HA contents. The voxel values were greatly influenced when the samples were scanned surrounded in air. However, the voxel values were not affected significantly in the existence of materials simulating oral hard tissues and/or a metal core post.nnnCONCLUSIONSnThere was a linear correlation between the voxel values of CBCT and the contents of HA rod samples. Our study indicated that it might be possible to evaluate bone mineral content(BMC) from the voxel values of CBCT for dental implant treatment.

Ultrasonic root-end preparation: clinical and radiographic evaluation of results.

PURPOSEnThis study evaluated the results of periradicular surgery performed using ultrasonic root-end preparation.nnnPATIENTS AND METHODSnThe course of healing during observation periods ranging from 6 months to 3 years was examined in 157 teeth.nnnRESULTSnOne hundred forty-five teeth were successfully treated, for a success rate of 92.4%.nnnCONCLUSIONnIt was concluded that the ultrasonic root-end preparation technique for periradicular surgery is a simple procedure that provides excellent results.

In vivo imaging of human labial glands using advanced optical coherence tomography.

OBJECTIVEnOptical coherence tomography (OCT) has emerged as a high-resolution noninvasive clinical imaging application. The purpose of this study was to show OCT images of human labial glands obtained using a swept-source (SS) OCT system.nnnSTUDY DESIGNnLabial gland OCT imaging was carried out using our new SS-OCT system for 5 healthy volunteers using a hand-held in vivo OCT scanning probe. The labial tissue was scanned in a superior to inferior direction in 2 and 3 dimensions.nnnRESULTSnThe resulting 2- and 3-dimensional ultrahigh-resolution images of in vivo OCT human labial minor salivary glands revealed the epithelium, connective tissue, lobes, and duct. OCT was capable of providing simultaneous and noninvasive structural information with high resolution.nnnCONCLUSIONnThis clinical imaging modality promises to have clinical impact in the diagnosis of such conditions as Sjögren syndrome and xerostomia.

Evaluation of oral vascular anomalies using optical coherence tomography

Optical coherence tomography (OCT) is a new method of biomedical imaging that can generate high-resolution, cross-sectional images of microstructures. The purpose of this study was to present the first OCT images of oral vascular anomalies using a new advanced OCT scanner that we have developed, and to discuss the application of our system for oral soft tissues. Knowledge of the size and area of the vascular structures can be useful for the diagnosis and choice of the best treatment. Before excision, oral vascular malformations were assessed by OCT in vivo. Histopathological sections were taken and compared with the OCT images to make clinicopathological correlations. OCT provided clear images of all the vascular lesions examined. Oval to roundish, signal-poor areas sharply demarcated by a surrounding signal-rich layer correlated well with the histopathological diagnosis. OCT images provide information about subsurface structure non-invasively that is otherwise obtainable only by examination of a biopsy specimen. The analysis of oral vascular lesions by OCT provides new insights into non-invasive diagnosis and can be helpful in the selection of the most appropriate treatment.

Factors influencing oral health-related quality of life (OHRQoL) among the frail elderly residing in the community with their family

The purpose of the present study was to identify factors that influence quality of life (QoL) among frail elderly individuals residing in the community, in order to improve the level of home care related to oral health. Participants were 100 pairs comprising elderly individuals requiring care and their family caregivers. Questionnaire items for the family caregivers related to demographic variables, hours spent caregiving per day, and duration of caregiving. Questionnaire items for the elderly recipients of care concerned demographic variables, activities of daily living (ADL), and cognitive status. According to bivariate analysis, oral health-related quality of life (OHRQoL) was significantly related to basic ADL, communication ADL (CADL), dysphagia risk, and duration of caregiving. From multiple regression analysis, dysphagia risk and CADL were extracted as factors influencing OHRQoL. Assessment of OHRQoL will be useful not only to detect oral health needs but also to evaluate the effect of oral health care in the elderly.

Postoperative irradiation after reconstructive surgery: comparative study of radiosensitivity between free-skin grafts and skin flaps

Radiation effects after reconstructive surgery (free-skin grafts and skin flaps) were studied in the rat, and the optimum time for irradiation was determined. The radiosensitivity of both free-skin grafts and skin flaps showed the same trend depending on time of irradiation after operation. The grafts or flaps irradiated in the hypervascular stage showed severe reactions to irradiation, whereas those irradiated in the hypovascular stage showed milder reactions in gross and microangiographic observation. Vascular damage should be given primary consideration when deciding the proper time for irradiation after reconstructive surgery. In general, free-skin grafts showed more severe reactions than skin flaps, especially in the grafts irradiated in the early stage after operation. The experimental results of this study cannot be readily transferred to a clinical setting, but they suggest that postoperative irradiation could be begun 3 to 4 weeks after operation with respect to graft or flap survival, and the results of the clinical cases almost coincide with these experimental results.

Blue rubber bleb nevus syndrome with oral hemangiomas

A case of blue rubber bleb nevus syndrome with oral hemangiomas is reported. Attention is directed to this syndrome because, although rare, it is usually associated with oral lesions. The blue rubber bleb nevus syndrome should always be considered a possibility in patients with oral hemangiomas and bluish skin nodules.

Effects of irradiation on grafted skin

The reaction of grafted skin to irradiation was studied in the rat and the optimum time for irradiation postoperatively was determined. There was a close correlation between the radiosensitivity and the vascularity of the graft and its recipient bed. Grafts showed different reactions depending on the time of irradiation after grafting. Those in the early hypovascular stage showed reactions similar to those of normal control skin. Severe reactions were observed in the hypervascular stage. Grafts in the late hypovascular stage showed more moderate reactions.

Location dependency of the spatial resolution of cone beam computed tomography for dental use

OBJECTIVEnThis study evaluates the spatial resolution of cone beam computed tomography for dental use (CBCT) via modulation transfer function (MTF) analyses.nnnSTUDY DESIGNnTwo models of CBCT system, 3DX FPD8 and FineCube v.12, were used. MTF analysis was applied to each CBCT system using a thin tungsten wire technique.nnnRESULTSnThe MTF curves in the radial direction on the XY-plane were concordant regardless of position, whereas the curves in the azimuthal direction tended to decrease as the distance from the rotation center increased. In the Z-axis direction, the MTF curve of the medial level of the field of view was superior to that of any other level.nnnCONCLUSIONnThe spatial resolution of CBCT systems depends on the location within the field of view. Because the spatial resolution was the highest in the medial level and rotation center position, an object should be placed at this position during a CBCT examination.

Localizing the mandibular canal on dental CT reformatted images: usefulness of panoramic views

PurposeThe aim of this study was to compare panoramic and paraxial views of dental CT reformatted images to detect the mandibular canal, and to evaluate the usefulness of the dental CT software function of “Outlining the Mandibular Canal in the Panoramic View”.MethodsOne hundred and fifty-five patients (310 sides), who underwent multi-slice computed tomography examination for pretreatment planning of dental implant were analyzed. After scanning, two types of dental CT reformatted image, panoramic and paraxial views were obtained. Two oral radiologists evaluated both views for the visibility of the mandibular canal using a 5-point rating scale: score 5, 100–80xa0% visible, to score 1, 20–0xa0% visible. The visibility scores of the two views were evaluated and compared by Wilcoxon’s signed rank test.ResultsThe meanxa0±xa0standard deviations of panoramic and paraxial views were 4.2xa0±xa01.1 and 3.5xa0±xa01.2, respectively, and the former was significantly higher than the latter (pxa0<xa00.001). On the basis of these results, we attempted to apply the function of “Outlining the Mandibular Canal in the Panoramic View” to cases with poor visibility of the canal (score 1, 2 or 3) on paraxial views. Consequently, we could reduce the number of such cases from 128 (41xa0%) to 56 (18xa0%).ConclusionsThe detectability of the mandibular canal was significantly higher in panoramic views than in paraxial views. Using the function of “Outlining the Mandibular Canal in the Panoramic View”, the precision for identifying the canal on paraxial views was considered to be improved.