Age estimation using pulp/enamel volume ratio of impacted mandibular third molars measured on CBCT images in a northern Chinese population.

The present study aims to evaluate the relation between chronological age and the ratio of pulp volume (PV) to enamel volume (EV) of impacted mandibular third molars (IMTMs) by using cone-beam computed tomography (CBCT) images and an improved 3D image segmentation technique. A sample of CBCT images of IMTM was collected from 414 northern Chinese subjects (214 male and 200 female clinical patients) ranging in age from 20 to 65 years. The GrowCut effect image segmentation (GCEIS) module algorithm was used to calculate the PV and EV from CBCT images. The total sample was divided into a training group and validation group in a ratio of 7 to 3. The PV/EV ratio (PEr) in the training sample was used to develop a mathematical formula for age estimation as follows: age = - 5.817-21.726 × Ln PEr (p < 0.0001) (Ln, natural logarithm). The mean absolute error (MAE) and root mean square error (RMSE) were used to determine the precision and accuracy of the mathematical formula in the validation group and all samples. The MAEs in the male, female, and pooled gender samples were 9.223, 7.722, and 8.41, respectively, and the RMSEs in the male, female, and pooled gender samples were 10.76, 9.58, and 9.986, respectively. The precise and accurate results indicate that the PEr of IMTM in CBCT images is a potential index for dental age estimation and is possible to be used in forensic medicine.

Environmental cue difference and training duration modulate spatial learning and cue preference in detour task.

In this study, we investigated how different environmental cue and the proficiency of body motion influenced detour learning behaviour and cue preference in cue conflict situations. Domestic chicks were trained to detour around an obstacle and follow a fixed route to rejoin with their partners. When the environmental cue was red versus blue vertical stripes, the chicks learned the detour task quicker, and as the number of training trials after route acquisition increased, they switched their preference from the environmental cue to a body-motion cue in the cue conflict test. On the other hand, when the environmental cue was vertical versus horizontal blue stripes, the chicks learned the detour task slower and showed a dependence on the body-motion cue regardless of the number of training trials performed after route acquisition. When the environmental cue was removed, most chicks could still successfully detour according to the specific route on which they had been trained. Furthermore, a significant difference in detour latency was found between chicks using the environmental cue and chicks using the body-motion cue, suggesting separate neuronal circuits responsible for processing the two types of information. Our results demonstrated that young domestic chicks could use both environmental cue and body-motion cues to memorize the route during the detour learning task; however, the detour route preference could be dynamically modulated by difference of the environmental cue and the number of training trials they received.

Knowledge, attitude and willingness of different ethnicities to participate in cadaver donation programs.

Knowledge, attitude and willingness of ethnic minorities in China towards cadaver donation programs were assessed. Questionnaire and interviews were conducted to investigate Yi, Bai, Hani, Dai and Han ethnicities. Educational level and per capita income of ethnic minorities were lesser than those of Han ethnicity (p<0.01). Agriculture was the primary occupation and proportions of technical personnel and public officials was lesser among ethnic minorities (p<0.01). Surveyed ethnic minorities universally practice religious traditions, Bai and Dai ethnicities practice Buddhist beliefs also (p<0.01). Knowledge of Yi, Bai, Hani and Dai ethnic respondents was lesser than those of Han ethnicity (p<0.01). Over 83.8% of Yi, Bai, Hani and Dai ethnicity residents were unwilling to register for body donation programs with receiving a driver's license (p<0.01). Less than 46.9% of ethnic minorities supported use of honorary certificates (p<0.01). Ethnic minorities were supportive of financial compensation for body donations and denied that financial compensation led to the commercialization of cadaver donation (p<0.01, p<0.01). Willingness of ethnic minorities to participate in cadaver donation programs was primarily related to religious beliefs (p<0.01), economic status (p<0.01). Knowledge, attitude and willingness of ethnic minorities to participate in cadaver donation programs were markedly different from those of Han ethnicity, and the religious belief and economic status played a decisive role. To increase participation, programs based on respecting religious belief should be developed to support improvements in economy, education, medical care and social security system.