O'Grady Paul W, McNamara James A, Baccetti Tiziano, Franchi Lorenzo
Graduate Orthodontic Program, University of Michigan, Ann Arbor, Mich 48109-1078, USA.
Am J Orthod Dentofacial Orthop. 2006 Aug;130(2):202-13. doi: 10.1016/j.ajodo.2004.12.023.
The aim of this prospective longitudinal clinical study was to evaluate the short-term and long-term changes in dental-arch dimensions in patients treated with either an acrylic splint rapid maxillary expander alone (RME-only) or a rapid maxillary expander combined with a mandibular removable Schwarz plate (RME-Sz) in the early mixed dentition, followed later by fixed appliances in the permanent dentition.
The dental casts of 27 RME-only patients were compared with those of 23 RME-Sz patients and 16 untreated controls (CTRL) with constricted maxillary arches at 4 times: pretreatment (T1), after expansion but before fixed appliance therapy (T2), after fixed appliance therapy (T3), and at long-term observation (T4). The mean ages for the treated groups were approximately 9 years at T1, 12 years at T2, 14 years at T3, and 20 years at T4. Arch width, arch depth, arch perimeter, and molar angulation were assessed in all subjects at all observation times. T1-T2, T2-T3, T3-T4, and T1-T4 changes were compared statistically in the treated groups with respect to the CTRL.
Treatment with an RME-only or an RME-Sz followed by fixed appliances produced significant short-term and long-term increases in maxillary arch widths compared with the CTRL. The RME-Sz led to significantly more favorable results than the RME-only protocol: (1) significantly greater increases in the transverse width of the mandibular arch and mandibular arch perimeter in the long term, and (2) uprighting of the mandibular posterior teeth buccally, thus allowing for an amount of maxillary expansion that was clinically effective for the correction of moderate tooth size-arch size discrepancies. In the overall observation interval, the significant increases in maxillary and mandibular arch perimeters in the RME-Sz group were 3.8 and 3.7 mm, respectively, when compared with the CTRL. The RME-only protocol produced modest long-term increases in maxillary arch perimeter (2.6 mm); the average long-term increase in mandibular arch perimeter (2.0 mm) in the RME-only group was not statistically significant.
The RME-Sz led to significantly more favorable results than the RME-only protocol.
这项前瞻性纵向临床研究的目的是评估在乳牙混合早期仅使用丙烯酸夹板快速上颌扩弓器（仅RME）或快速上颌扩弓器联合下颌可摘式施瓦茨矫治器（RME-Sz）进行治疗的患者牙弓尺寸的短期和长期变化，随后在恒牙列期使用固定矫治器。
将27例仅使用RME治疗的患者的牙模与23例使用RME-Sz治疗的患者以及16例上颌弓狭窄的未治疗对照者（CTRL）的牙模在4个时间点进行比较：治疗前（T1）、扩弓后但在固定矫治器治疗前（T2）、固定矫治器治疗后（T3）以及长期观察时（T4）。治疗组在T1时的平均年龄约为9岁，T2时为12岁，T3时为14岁，T4时为20岁。在所有观察时间点对所有受试者的牙弓宽度、牙弓深度、牙弓周长和磨牙角度进行评估。在治疗组中，将T1-T2、T2-T3、T3-T4以及T1-T4的变化与CTRL进行统计学比较。
与CTRL相比，仅使用RME或RME-Sz后使用固定矫治器治疗在短期和长期均使上颌牙弓宽度显著增加。RME-Sz比仅使用RME方案产生了明显更有利的结果：（1）长期来看，下颌牙弓横向宽度和下颌牙弓周长显著增加更多；（2）下颌后牙颊向直立，从而允许进行临床上对纠正中度牙齿大小与牙弓大小差异有效的上颌扩弓量。在整个观察期内，与CTRL相比，RME-Sz组上颌和下颌牙弓周长的显著增加分别为3.8和3.7mm。仅使用RME方案使上颌牙弓周长有适度的长期增加（2.6mm）；仅使用RME组下颌牙弓周长的平均长期增加量（2.0mm）无统计学意义。
RME-Sz比仅使用RME方案产生了明显更有利的结果。
