[Comparison of three-dimensional position of maxillary dentition model treated with two digital transfer methods].

Objective: To compare and evaluate the difference in maxillary dentition position using an anatomical facebow and jaw movement analyzer. Methods: From March to May 2023, 15 medical interns from Yantai Stomatological Hospital were recruited, including 9 males and 6 females, aged 20-25 years. Digital models and plaster models of maxillary dentition were obtained from the 15 medical interns. The anatomical facebow group (AFB) and jaw movement analyzer group (JMA) were used to transfer the position of the maxillary dentition to the virtual articulator. The virtual occlusal articulator module of exocad denture design software was used to measure the inclination angle of the occlusal plane of the two groups, the distance between the mesio-incisal angle of the left maxillary central incisor and the lateral center point of the lateral condylar sphere of the virtual occlusal articulator, the distance between the mesial buccal cusp of the maxillary first molar and the lateral center point of the lateral condyle sphere of the virtual articulator. The same marks (mesial incisor point of left maxillary central incisor and mesial buccal cusp point of both maxillary first molars) were measured in two groups of maxillary dentition, and the root-mean-square error between 3 points was calculated. Results: The occlusal plane inclination angle in AFB group (9.11°±3.85°) was significantly larger than that in JMA group (4.94°±2.69°) (t=10.45, P<0.001). There were significant differences between AFB and JMA groups. The distances from the mesial cusp of the left first molar to the lateral center of the left condylar, from the mesial cusp of the left maxillary central incisor to the lateral center of the left condylar[(91.75±3.05), (129.09±4.60) mm]were significantly smaller than those in the JMA group[(95.68±5.45), (132.41±5.64) mm](t=-4.48, P=0.001; t=-4.21, P=0.001). In both groups of models, the distance of the mesial cusp of the left maxillary central incisor was (8.81±2.56) mm, and the distance between mesial buccal cusp of maxillary left first molar was (7.56±2.49) mm, the distance between mesial buccal cusp of maxillary right first molar was (7.13±2.77) mm; the root mean square error was (7.93± 2.94) mm. Compared with 0, the difference was statistically significant (t=10.45, P<0.001). Conclusions: There were differences between the two methods (anatomical facebow and the jaw movement analyzer) for transferring the maxillary dentition position to the three-dimensional space position of the virtual articulator.

A novel method of identification of in-ring decay and its application in the half-life estimates of 94mRu44.

Isochronous Mass Spectrometry is a practical approach for studying decays of short-lived isomers. However, solely relying on the time stamps between the isomer and ground state does not provide clear sign of decay. To address this issue, we proposed a method for extracting decay time point by analyzing the residuals of time stamps within a window of (20µs, 180µs) after the start of data acquisition. Decay events out of the window were disregarded due to poor accuracy of revolution time. In this paper, we propose a novel approach based on the discrete Fourier transform technique, which was tested by simulation data. We found that the accuracy of the decay time point can be improved, leading to an expanded window of (15µs, 185µs). Furthermore, as the novel method was applied to experimental data, additional five decay events were identified. The newly determined half-life of 94mRu44+ is consistent with the previous value.