Quinzi Vincenzo, Mummolo Stefano, Bertolazzi Francesca, Campanella Vincenzo, Marzo Giuseppe, Marchetti Enrico
Department of Life, Health & Environmental Sciences, Postgraduate School of Orthodontics, University of L'Aquila, 67100 L'Aquila, Italy.
Department of Clinical Science and Translational Medicine, University of Rome "Tor Vergata", 00133 Rome, Italy.
J Funct Morphol Kinesiol. 2020 Aug 6;5(3):61. doi: 10.3390/jfmk5030061.
Dental crowding is more pronounced in the mandible than in the maxilla. When exceeding a significant amount, the creation of new space is required. The mandibular expansion devices prove to be useful even if the increase in the lower arch perimeter seems to be just ascribed to the vestibular inclination of teeth. The aim of the study was to compare two activation protocols of the Schwartz appliance in terms of effectiveness, particularly with regard to how quickly crowding is solved and how smaller is the increasing of vestibular inclination of the mandibular molars.
We compared two groups of patients treated with different activation's protocols of the lower Schwartz appliance (Group 1 protocol consisted in turning the expansion screw half a turn twice every two weeks and replacing the device every four months; Group 2 was treated by using the classic activation protocol-1/4 turn every week, never replacing the device). The measurements of parameters such as intercanine distance (IC), interpremolar distance (IPM), intermolar distance (IM), arch perimeter(AP), curve of Wilson (COW), and crowding (CR) were made on dental casts at the beginning and at the end of the treatment.
A significant difference between protocol groups was observed in the variation of COWL between time 0 and time 1 with protocol 1 with protocol 1 subjects showing a smaller increase in the parameter than protocol 2 subjects. The same trend was observed also for COWR, but the difference between protocol groups was slightly smaller and the interaction protocol-by-time did not reach the statistical significance. Finally, treatment duration in protocol 1 was significantly lower than in protocol 2.
The results of our study suggest that the new activation protocol would seem more effective as it allows to achieve the objective of the therapy more quickly, and likely leading to greater bodily expansion.
下颌牙列拥挤比上颌更为明显。当拥挤程度超过一定量时，就需要开辟新的间隙。下颌扩弓装置已被证明是有效的，即便下牙弓周长的增加似乎只是由于牙齿的颊向倾斜。本研究的目的是比较施瓦茨矫治器的两种加力方案在有效性方面的差异，特别是在解决拥挤的速度以及下颌磨牙颊向倾斜增加程度方面。
我们比较了两组使用不同加力方案的下颌施瓦茨矫治器进行治疗的患者（第1组方案为每两周将扩弓螺丝旋转半圈两次，每四个月更换矫治器；第2组采用经典加力方案——每周旋转1/4圈，不更换矫治器）。在治疗开始和结束时，对模型进行尖牙间距离（IC）、前磨牙间距离（IPM）、磨牙间距离（IM）、牙弓周长（AP）、威尔逊曲线（COW）和拥挤度（CR）等参数的测量。
在时间0到时间1之间，第1组和第2组在COWL变化方面存在显著差异，第1组患者该参数的增加幅度小于第2组患者。COWR也观察到相同趋势，但两组间差异略小，且方案与时间的交互作用未达到统计学显著性。最后，第1组的治疗时间显著低于第2组。
我们的研究结果表明，新的加力方案似乎更有效，因为它能更快地实现治疗目标，并且可能导致更大的整体扩弓效果。
