Zimmer Bernd, Rottwinkel Yvonne
Orthodontic Practice, Kassel, Germany.
J Orofac Orthop. 2002 Sep;63(5):400-21. doi: 10.1007/s00056-002-0208-0.
Orthodontic space closure in situations with bilateral aplastic lower second premolars without maxillary extractions is a rarely practiced treatment method. Due to the high risk of severe side effects, preference is currently given to the maintenance of deciduous second molars and subsequent prosthodontic solutions. As a combination of Class I push and Class II pull mechanics seemed likely to reduce secondary effects by transferring the anchorage site from the reactive lower anterior teeth to the more resistant upper arch, a clinical study was carried out in order to investigate effects and secondary effects of the mechanics.
Casts, panoramic radiographs and lateral headfilms of 13 consecutively treated, non-selected adolescents (seven boys, six girls, mean age at start of treatment 13 years 4 months) were evaluated. In six patients a Jasper Jumper trade mark was inserted in addition for a mean period of 6 months.
The treatment outcome after a mean period of 3 years and 1 month showed in almost all cases the desired Class III molar occlusion of one cusp width (+/- 1/4 cw) with overbite and overjet within the normal range. Analyses of static and dynamic occlusion revealed anterior/canine protected articulation and a satisfactory number of centric contact points. A significant space gain (p </= 0.01) distal to the lower second molars (right side: 4.9 mm, left side: 5,3 mm) confirmed a relevant movement of the lower molars to mesial and an increased probability of being able to save the lower third molars as a natural substitute for the aplastic second premolars. Mean reductions in incisor inclination were low (0.5 degrees ) in the upper and moderate (4.3 degrees ) in the lower arch.
Bearing in mind that supporting anchorage measures may be needed to compensate for unfavorable cofactors, the investigated treatment method can be recommended for those patients giving preference to a prosthetic-free dentition and to avoiding surgical interventions.
在双侧下颌第二前磨牙发育不全且不拔除上颌牙齿的情况下进行正畸间隙关闭是一种很少采用的治疗方法。由于严重副作用的风险较高，目前更倾向于保留乳牙第二磨牙并采用后续的修复治疗方案。由于I类推和II类拉力学的组合似乎有可能通过将支抗部位从反应性较强的下前牙转移到抗力更强的上牙弓来减少副作用，因此开展了一项临床研究以调查该力学的效果和副作用。
对13名连续接受治疗的非选择性青少年（7名男孩，6名女孩，治疗开始时平均年龄为13岁4个月）的模型、全景X线片和头颅侧位片进行了评估。6名患者额外佩戴了平均时长为6个月的Jasper Jumper矫治器。
平均3年1个月的治疗结果显示，几乎在所有病例中都实现了理想的III类磨牙咬合，尖对尖宽度为一个牙尖宽度（±1/4牙尖宽度），覆合和覆盖在正常范围内。静态和动态咬合分析显示前牙/尖牙保护式咬合以及令人满意的正中接触点数量。下颌第二磨牙远中显著的间隙增加（p≤0.01）（右侧：4.9毫米，左侧：5.3毫米）证实了下颌磨牙向近中方向的相关移动，以及能够保留下颌第三磨牙作为发育不全的第二前磨牙的天然替代物的可能性增加。上颌切牙倾斜度的平均降低幅度较小（0.5度），下颌牙弓的降低幅度适中（4.3度）。
考虑到可能需要采取支持性支抗措施来补偿不利的协同因素，对于那些倾向于无修复体牙列并避免手术干预的患者，可以推荐所研究的治疗方法。
