Prevention is the most effective way to reduce dental caries. In order to provide a simple way to achieve oral healthcare direction in daily life, dual Channel, portable dental Imaging system that combine white light with autofluorescence techniques was established, and then, a group of volunteers were recruited, 7200 tooth pictures of different dental caries stage and dental plaque were taken and collected. In this work, a customized Convolutional Neural Networks (CNNs) have been designed to classify dental image with early stage caries and dental plaque. Eighty percentage ([Formula: see text]) of the pictures taken were used to supervised training of the CNNs based on the experienced dentists’ advice and the rest 20% ([Formula: see text]) were used to a test dataset to test the trained CNNs. The accuracy, sensitivity and specificity were calculated to evaluate performance of the CNNs. The accuracy for the early stage caries and dental plaque were 95.3% and 95.9%, respectively. These results shown that the designed image system combined the customized CNNs that could automatically and efficiently find early caries and dental plaque on occlusal, lingual and buccal surfaces. Therefore, this will provide a novel approach to dental caries prevention for everyone in daily life.
Orthokeratology (OK) is becoming a mainstream modality for myopia correction and control, but its underlying mechanism is not yet fully understood. In this study, the biomechanical response of cornea under the OK lens was investigated to further understand the mechanism of OK therapy. Numerical models of the cornea and OK lens with different corneal refractive powers and myopia degrees were established to analyze features and differences of the spatial displacement and stress distribution in different areas of the anterior corneal surface by finite element method. Displacement distributions on the anterior cornea surface with refractive powers of 39.5, 43, 46 D, and myopia degrees of −1.0, −3.0, −6.0 D demonstrate similar deformation trends and nearly rotationally symmetrical attributes of different corneal parameters. Displacement of mid‐peripheral cornea was significantly high compared with that of the central and peripheral cornea, peaking at ~2.4 mm off the corneal apex. The stress increased with the increase in myopia degrees and was significantly large for the myopia degrees of −6.0 D at S1; the stress at S2 and S6 was low and stable and did not differ much at S3; the stress at S4 and S5, however, was extremely high. In summary, simulation result of orthokeratology can effectively evaluate the performance of OK lens and it properly associates with the differential map of the corneal topography. The base curve of the OK lens may also play a role in mid‐peripheral corneal steepening. The design around the OK lens' alignment curve needs to be optimized.
In order to meet the demands of myopia prevention, as well as the increasing needs of measurement for refractive and cataract operations in China, a new axial length (AL) measurement system combining an improved Twyman-Green interferometer with digital signal processing has been established. The ALs of 33 eyes of different optical refractive subjects (À8.50~0.50 D) were measured with the New AL and intraocular lens (IOL) master. The repeatability of measurements with the New AL was assessed using coefficient of variation (CoV) and intra-group correlation coefficient (ICC). Comparison, correlation, linear regression and agreement of AL between devices were analyzed. There was good repeatability (CoV = 0.0617%, ICC = 0.9999) with the New AL and great agreement has been obtained with both devices. These show that the New AL is capable of providing precise AL values over the normal AL range compared to the IOL master, and indicate that the New AL developed can be used for routine clinical AL measurements.
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