肌等压区排牙法全口义齿对咀嚼肌肌电和咬合力的影响

目的比较肌等压区排牙法全口义齿（neutral zonedentures，ND）和传统全口义齿（conventional complete dentures，CD）修复后无牙颌患者咀嚼肌肌电活动和咬合力的变化差异，以期了解肌等压区排牙法全口义齿的修复效果。方法选择10例牙槽嵴严重萎缩低平的无牙颌患者，记录其分剐戴用ND和CD1个月、3个月时的咬合力和颞肌前束（temporal anterior，TA）、嚼肌（masstter muscle，MM）、二腹肌前腹（diagastric anterior，DA）在咀嚼口香糖及花生米时的肌电图。根据记录阶段分为ND1个月组、ND3个月组、CD1个月组和CD3个月组。采用配对t检验分析ND1个月-CD1个月组、ND3个月-CD3个月组之间相应指标的差异。结果（1）咀嚼口香糖：TA、MM肌电活动ND1个月组〉CD1个月组，ND组咀嚼周期（TCD）、活动期与间歇期比值（AP／RP）小于CD组（P〈0．05）；（2）咀嚼花生米：TA、MM肌电活动ND3个月组〉CD3个月组，ND组咀嚼周期、活动期与间歇期比值小于CD组（P〈0．05）；（3）咬合力：ND1个月组〉CD1个月组（P〈0．05）。结论与传统全口义齿相比，肌等压区排牙法全口义齿戴用者显示出较好的咀嚼肌功能。

Effect of neutral zone dentures on EMG of masticatory muscles and biting force

Objective To evaluate the effectiveness of neutral zone dentures （ND） and conventional complete dentures （CD） on electric activities of masficatory muscles and biting force in edentulous patients. Methods Ten edentulous patients were selected either ND or CD was worn. Biting force and surface electromyogram of temporal anterior （TA）, masseter muscle （MM） and diagastric anterior （DA） were detected in these patients during clench and chewing movement after 1 and 3 months. The patients were recorded as 4 groups ： ND-1 month group, ND-3 months group, CD-1 month group and CD-3 months group. Corresponding parameters between ND-1 month group were compared by paired t-tests. Results and CD-1 month group, ND-3 months and CD-3 months （ 1 ） In chewing gum movement, muscular activity of TA and MM were higher in ND-1 month group than in CD1 month group; total cycle duration （TCD） and ratio of activation period to relaxation period （AP/RP） were lower in group ND than in group CD. （2） In chewing peanuts movement, muscular activity of TA, MM were higher in ND-3 months group than in CD-3 months group; TCD,AP/RP in group ND were lower than in group CD. （3） The biting force in ND-1 month group was higher than in CD-1 month group. Conclusion Compared with patients wearing CD, the patients wearing ND have better masticatory muscle functions.