Mitra Rajat, Londhe S M, Kumar Prasanna
Associate Professor (Orthodontics), Dept. of Dental Surgery, AFMC, Pune - 40.
DDGDS (E & S), O/o DGDS, IHQ, MOD (Army), L Block, New Delhi - 11001.
Med J Armed Forces India. 2011 Apr;67(2):152-6. doi: 10.1016/S0377-1237(11)60017-8. Epub 2011 Jul 21.
Aim of this study was to compare the rate of space closure between E-chain mechanics in one side of upper arch and by elastomeric module with ligature wire on the contralateral side in same patient.
Thirty bimaxillary dentoalveolar protrusion cases were taken up for comprehensive fixed orthodontic treatment after extraction of all first premolars to retract both upper and lower anterior teeth. After initial alignment and levelling, alginate impressions were made for upper and lower arches and models constructed. In the upper arch model a vernier caliper was used to measure the extraction space in both sides from middle point of distal surface of canine to the middle most point of mesial surface of second premolar. This is the amount of space present before the onset of retraction mechanics. During space closure procedure two different retracting components were applied in right and left sides of each case. On right side elastic chain (E-chain) applied in both upper and lower arches and on left side elastomeric module with steel ligature (0.010") stretched double its diameter fixed in both arches. Both the mechanisms produced approximately 250-300 g of force as measured by a tension gauge. After onset of retraction mechanism all patients were recalled after every six weeks for three visits. In all these three visits modules and E-chains were changed. In all three visits impression was made, models constructed, and the remaining available space was measured by a vernier caliper up to 0.1 mm level variations.
Mean value for total space closure in case of E-chain was 2.777 mm whereas in case of module with ligature wire the value increased to 3.017 mm. Mean value for rate of space closure in case of E-chain was 0.2143 mm, whereas in case of module with ligature wire the value increased to 0.2343 mm with a standard deviation of 0.001104 and 0.001194, respectively. The standard deviation for total space closure was 0.1305 for E-chain and 0.1487 for module with ligature wire.
Space closure by elastomeric module with ligature wire is better than the E-chain.
本研究的目的是比较同一患者上颌弓一侧使用E链力学装置与对侧使用带结扎丝的弹性模块进行间隙关闭的速率。
选取30例双颌牙列前突患者，拔除所有第一前磨牙后进行全面的固定正畸治疗，以内收上下前牙。在初始排齐整平后，制取上下颌藻酸盐印模并制作模型。在上颌模型中，使用游标卡尺测量两侧从尖牙远中面中点到第二前磨牙近中面最中点的拔牙间隙。这是内收力学装置开始使用前的间隙量。在间隙关闭过程中，对每个病例的左右两侧应用两种不同的内收部件。右侧上下颌均应用弹性链（E链），左侧上下颌均固定使用直径拉伸两倍的0.010英寸钢丝结扎的弹性模块。两种装置通过张力计测量产生的力均约为250 - 300克。在内收力学装置开始使用后，每6周召回所有患者进行三次复诊。在这三次复诊中均更换模块和E链。每次复诊均制取印模、制作模型，并使用游标卡尺测量剩余可用间隙，精确到0.1毫米水平变化。
E链组间隙关闭总量的平均值为2.777毫米，而带结扎丝模块组该值增至3.017毫米。E链组间隙关闭速率的平均值为0.2143毫米，而带结扎丝模块组该值增至0.2343毫米，标准差分别为0.001104和0.001194。E链组间隙关闭总量的标准差为0.1305，带结扎丝模块组为0.1487。
带结扎丝的弹性模块关闭间隙的效果优于E链。
