https://www.selleckchem.com/products/hexa-d-arginine.html This paper introduces these recent developments in CAD/CAM of RPD.Objective To investigate the effectiveness of a digital virtual simulation training system applied in the preclinical teaching of access and coronal cavity preparation. Methods Twenty dental undergraduate students from Peking University School and Hospital of Stomatology were recruited and divided randomly and equally into two groups according to the random number method after being unified with theory training, including access and coronal cavity preparation skills assessment form and Simodont system operation manual. Tests for access and coronal cavity preparation skills by using standard simulation plastic teeth were performed and the scores were recorded as baseline for each student. Students in group of virtual simulation priority were trained using Simodont virtual simulation system, while those in group of phantom-simulator priority were trained using conventional phantom-simulator system. Access and coronal cavity preparation skills of standard simulation plastic teeth were assessed once again and recl simulation system has the characteristics of repeatability, multi-dimension and multiple practice, and provides me with more attention to details" [80% (16/20)], however "it needs to be improved and upgraded to be close to the conventiaonl phantom-simulator system" [90% (18/20)]. Conclusions Compared with using the conventional phantom-simulator system only, the preclinical teaching effectiveness of access and coronal cavity preparation could be effectively improved by using Simodont virtual simulation system combined with the phantom-simulator training system and might influenced by the training sequence.Objective To provide a scientific basis for the standardized operation of clinical disinfection by comparing and analyzing the influence of disinfection times on the accuracy of digital intraoral scanning. Methods The author prepared 10