Clinical Application of CAD/CAM Customized Zirconia Abutment in Maxillary Anterior Region

[Objectives]To explore the difference between the CAD/CAM customized zirconia abutment and the finished titanium abutment in the maxillary anterior region.[Methods]A total of 60 implants were selected from 60 patients who had undergone maxillary single anterior implant implantation in the Department of Oral and Maxillofacial Surgery,Affiliated Hospital of Qingdao University from July 2017 to July 2018.They were randomly divided into an observation group and a control group(30 patients/group).The observation group used CAD/CAM customized zirconia abutment and all-ceramic crown,while the control group used finished titanium abutment and all-ceramic crown.Twelve months after the crown restoration,mechanical complications,pink esthetic(another spelling of aesthetic)score(PES)and white esthetic score(WES),and patient satisfaction were used as clinical observation indicators to evaluate the restoration effect.[Results]For 12 months after crown restoration,the implant survival rate of the two groups of patients was 100%,and there was no abutment breakage,loosening,falling off,or screw loosening and breakage.The PES and WES of the observation group were significantly higher than those of the control group(P<0.05).The patient satisfaction of the observation group was significantly higher than those of the control group(P<0.05).[Conclusions]CAD/CAM customized zirconia abutment implant restoration in the maxillary anterior region can obtain good esthetic restoration effect in a short term,and has good clinical application effect.

Conformational change-modulated spin transport at single-molecule level in carbon systems

Controlling the spin transport at the single-molecule level,especially without the use of ferromagnetic contacts,becomes a focus of research in spintronics.Inspired by the progress on atomic-level molecular synthesis,through firstprinciples calculations,we investigate the spin-dependent electronic transport of graphene nanoflakes with side-bonded functional groups,contacted by atomic carbon chain electrodes.It is found that,by rotating the functional group,the spin polarization of the transmission at the Fermi level could be switched between completely polarized and unpolarized states.Moreover,the transition between spin-up and spin-down polarized states can also be achieved,operating as a dual-spin filter.Further analysis shows that,it is the spin-dependent shift of density of states,caused by the rotation,that triggers the shift of transmission peaks,and then results in the variation of spin polarization.Such a feature is found to be robust to the length of the nanoflake and the electrode material,showing great application potential.Those findings may throw light on the development of spintronic devices.

Survey of Temporomandibular Disorder in Male Candidates of Conscription Age

[Objectives] To study the temporomandibular disorder(TMD) in male candidates of conscription age. [Methods] The TMD was surveyed in 2 152 young males who participated in 2015, 2016 and 2017 physical examinations for conscription in Qingzhou City, Weifang of Shandong Province. [Results] Cases with previous positive symptoms and with positive clinical signs respectively accounted for 5.02% and 18.91% of the whole respondents. Among the three major symptoms, the occurrence of clicking, accounting for 17.7% of the total case amount, ranked the first; among 407 cases with positive clinical signs, the top two symptoms were simple clicking(50.86%) and clicking with abnormal mandibular movement(36.85%). [Conclusions] TMD occurs in male candidates of conscription age with a relatively high occurrence, but most cases are mild with clicking as the major symptom.