日本人と白人における歯・顎顔面形態の特徴に基づいた矯正治療のアプローチについて

Recently, with the increasing opportunities for global travel and the immigration of peoples, orthodontists may be required to treat patients of different racial origin. It is imperative to understand the morphological difference between racial groups to appreciate the aetiology of the malocclusions, and hence, to ensure that treatment is appropriately directed. This clinical topics outlines some of the differences in the morphology, aetiology, and orthodontic treatment outcomes for Japanese and Caucasian populations

日本人skeleatl I, skeletal III症例の歯列弓と顎顔面頭蓋における形態学的関係に関する研究

Available studies about differences among races, related to prevalence of malocclusion or morphology of head and dental arches, suggest a hypothesis that the high prevalence of skeletal Class III malocclusion in Asian ancestry populations could be correlated with a tendency toward a brachycephalic head form and larger arches widths. The purpose of the present study was to evaluate anteroposterior relationship of upper and lower jaws associated to form of dental arches, maxilla, mandible, face and head. Materials in this research consisted of pretreatment lateral and posteroanterior cephalometric radiographs and orthodontic models of Japanese females with skeletal Class I and Class III. Strong correlations between head form and jaws anteroposterior relationship could not be found. However, results indicated that skeletal Class III have statistically significant smaller length of maxilla and greater length of mandible, than the skeletal Class I group. Moreover, basal arch length and width of mandible were significantly bigger in skeletal Class III group. These results suggest that skeletal Class III, at least in this sample, might be associated to local malformation factors

Occlusogramを用いたIndividualized finishing arch wireの作製

The purpose of this study was to test the premise that by tracing occlusograms at the pretreatment stage, one can construct a precise finishing arch wire. The sample consisted of 22 male and 20 female dental students with skeletal Class I and near-normal occlusion. Occlusograms were taken for all plaster dental casts with 0.018 x 0.025 slot edgewise pre-an-gulated and pre-torqued brackets attached to all teeth. Futhermore, our method was applied clinically and an illustrative case is presented. Three different arches (A-arch; a smooth line drawn through the contact points of anterior and posterior teeth, B-arch; constructed by drawing a smooth curve through the cusp tips and incisive edges and C-arch; represented the 0.016 nitinol arch wire) showed a close fit as determined by the fourth degree polynomial equation, with r＾2 of 0.99

Multicascade-linked synthetic wavelength digital holography using an optical-comb-referenced frequency synthesizer

Digital holography (DH) is a promising method for non-contact surface topography because the reconstructed phase image can visualize the nanometer unevenness in a sample. However, the axial range of this method is limited to the range of the optical wavelength due to the phase wrapping ambiguity. Although the use of two different wavelengths of light and the resulting synthetic wavelength, i.e., synthetic wavelength DH, can expand the axial range up to a few tens of microns, this method is still insufficient for practical applications. In this article, a tunable external cavity laser diode phase-locked to an optical frequency comb, namely, an optical-comb-referenced frequency synthesizer, is effectively used for multiple synthetic wavelengths within the range of 32 um to 1.20 m. A multiple cascade link of the phase images among an optical wavelength (= 1.520 um) and 5 different synthetic wavelengths (= 32.39 um, 99.98 um, 400.0 um, 1003 um, and 4021 um) enables the shape measurement of a reflective millimeter-sized stepped surface with the axial resolution of 34 nm. The axial dynamic range, defined as the ratio of the maximum axial range (= 0.60 m) to the axial resolution (= 34 nm), achieves 1.7*10^8, which is much larger than that of previous synthetic wavelength DH. Such a wide axial dynamic range capability will further expand the application field of DH for large objects with meter dimensions.Comment: 19 pages, 7 figure

Adaptive sampling dual terahertz comb spectroscopy using dual free-running femtosecond lasers

Terahertz (THz) dual comb spectroscopy (DCS) is a promising method for high-accuracy, high-resolution, broadband THz spectroscopy because the mode-resolved THz comb spectrum includes both broadband THz radiation and narrow-line CW-THz radiation characteristics. In addition, all frequency modes of a THz comb can be phase-locked to a microwave frequency standard, providing excellent traceability. However, the need for stabilization of dual femtosecond lasers has often hindered its wide use. To overcome this limitation, here we have demonstrated adaptive-sampling THz-DCS, allowing the use of free-running femtosecond lasers. To correct the fluctuation of the time and frequency scales caused by the laser timing jitter, an adaptive sampling clock is generated by dual THz-comb-referenced spectrum analysers and is used for a timing clock signal in a data acquisition board. The results not only indicated the successful implementation of THz-DCS with free-running lasers but also showed that this configuration outperforms standard THz-DCS with stabilized lasers due to the slight jitter remained in the stabilized lasers

Improvement of dynamic range and repeatability in refractive-index-sensing optical comb by combination of saturable-absorber-mirror mode-locking with intracavity multi-mode interference fiber sensor

Mode-locked fiber comb equipped with multi-mode-interference fiber sensor functions as high-precision refractive-index (RI) sensor benefitting from precise radio-frequency measurement. However, its dynamic range and repeatability are hampered by inherent characteristics in nonlinear-polarization-rotation mode-locking oscillation. In this article, we introduce saturable-absorber-mirror mode-locking for RI sensing with wide dynamic range and high repeatability. While the RI dynamic range was expanded to 41.4 dB due to high robustness to cavity disturbance, self-starting capability without the need for polarization control improves the RI sensing repeatability to 1.10×10-8 every mode-locking activation. Improved dynamic range and repeatability will be useful for enhanced performance of RI sensing