Objective: To evaluate the efficiency of maxillary expansion with clear aligners and to analyze the possible influence factors. Methods: Thiry-one clear aligner cases (Invisalign) with maxillary expansion were enrolled in this study. The three-dimensional (3D) digital models of pre-treatment, planned in Clincheck software and post-treatment were collected. Upper dental arch width, buccal inclination of posterior teeth, and the expansion efficiency (expansion acquired/expansion planned) were measured and calculated. The impact of factors such as planned buccal inclination, planned expansion amount, attachment, and the mode of expansion on the expansion efficiency were analyzed. Results: The increases of upper arch width in canine, 1st and 2nd premolar, 1st and 2nd molar were (2.0±1.3), (2.8±1.5), (3.0±1.4), (1.8±1.0) and 0.5 (0.1, 1.1) mm, with their efficiency of 68%, 70%, 68%, 55% and 29%, respectively. The posterior teeth showed significantly more buccal inclination than the planned position (P<0.05). However, the most buccally inclined tooth detected in 1st molars was only 3.1°±3.9°. When the planned inter-molar width increase was less than 2 mm (n=15), the expansion efficiency of premolars was higher compared with those cases with the planned inter-molar width increase more than 2 mm (n=16, P<0.05). The planned buccal inclination, attachments, and the expansion mode had no significant effect on the expansion efficiency (P>0.05). Conclusions The expansion of maxillary arch with clear aligners was achieved by the buccal movement of the posterior teeth with limited buccal inclination. The efficiency of expansion declines from 1st premolars to second molars. The planned inter-molar width had a significant influence on the efficiency of premolar expansion.

Objective To improve the stability and practicability of field liquid transfusion control system.Methods SPCE062A 's high accurate AD was used to acquire the dropping speed,and a new method for weight sensor 's self proofread was applied.Results The infrared photoelectric sensor was removed,so the monitoring part could work with any appropriate sensor.Conclusion The system cost is decreased and its stability and availability are enhanced.[Chinese Medical Equipment Journal,2008,29(2):66-67]

Objective To design a more rapid and convenient infusion monitoring system.Methods Pentium series were used as its master and the MCU as its slaves.The management was based on RS232 standard.Results In the nursing station,nurses can monitor the fusion state of all patient rooms in the hospital.Conclusion It is proved that this system is simple,cheap and practical.[Chinese Medical Equipment Journal,2008,29(3):61-62,65]