Mutinelli Sabrina, Cozzani Mauro, Manfredi Mario, Bee Marco, Siciliani Giuseppe
Department of Orthodontics, University of Ferrara, Italy.
Eur J Orthod. 2008 Oct;30(5):469-76. doi: 10.1093/ejo/cjn045. Epub 2008 Sep 12.
The purpose of this research was to evaluate changes in upper arch dimension and form following rapid maxillary expansion (RME) using a modified Haas appliance in the primary dentition. The sample comprised 49 children [17 males, 32 females, mean age 7 years 5 months, standard deviation (SD) 1 year 1 month] with a crossbite or maxillary crowding. Twenty patients had a normal SN-GoGn angle (7 males, 13 females, mean 33.25 degrees, SD 2.10), three were low angle (1 male, 2 females, mean 27.67 degrees, SD 2.31), and 22 were high angle (8 males, 14 females, mean 39.95 degrees, SD 3.15). The vertical dimensions of four patients could not be measured, due to the unavailability of radiographs. Expansion was undertaken to either correct a crossbite or treat maxillary crowding. The upper dental casts were analysed using a computerized system: before treatment (T1), at appliance removal (T2), and 2 years 4 months after appliance removal (T3). Using bootstrap statistical analysis applied to distance ratio values [Euclidean distance matrix analysis (EDMA)], it was found that 48 patients showed a change in arch form. In 40.82 per cent (n = 20, group A), the arch form changed from T1 to T2, T1 to T3, and T2 to T3. In 32.65 per cent (n = 16, group B), it varied from T1 to T2 but relapsed at T3 to the form of T1. For 24.5 per cent (n = 12, group C), it changed from T1 to T2 but maintained the same form at T3. The favourable characteristics for obtaining expansion, identified by logistic regression analysis, were being male, of an immature stage of dental development (lateral incisor not fully erupted) and the presence of a lateral crossbite. Intercanine and intermolar widths, arch length, and the distance between the interincisive point and the line joining the canines (depth of the intercanine arch) at the different time points were analysed using a two-tailed t-test (P < 0.05). For the whole group, the increase in intercanine and intermolar width and in the depth of the intercanine arch was significant. Comparison between groups A, B, and C was undertaken using an analysis of variance, but there was no significant difference between the groups. This modified type of Haas appliance was able to increase the transverse dimension of the maxillary dental arch in the mixed dentition. The most appropriate timing for treatment appears to be before the eruption of the permanent lateral incisors.
本研究的目的是评估在乳牙列中使用改良型哈斯矫治器进行快速上颌扩弓（RME）后上颌牙弓尺寸和形态的变化。样本包括49名患有反牙合或上颌拥挤的儿童[17名男性，32名女性，平均年龄7岁5个月，标准差（SD）1年1个月]。20例患者的SN-GoGn角正常（7名男性，13名女性，平均33.25度，SD 2.10），3例为低角（1名男性，2名女性，平均27.67度，SD 2.31），22例为高角（8名男性，14名女性，平均39.95度，SD 3.15）。由于无法获得X线片，4例患者的垂直尺寸无法测量。扩弓的目的是纠正反牙合或治疗上颌拥挤。使用计算机系统对上颌石膏模型进行分析：治疗前（T1）、矫治器拆除时（T2）以及矫治器拆除后2年4个月（T3）。应用自抽样统计分析方法对距离比值[欧几里得距离矩阵分析（EDMA）]进行分析，发现48例患者的牙弓形态发生了变化。40.82%（n = 20，A组）的患者牙弓形态从T1到T2、T1到T3以及T2到T3均发生了改变。32.65%（n = 16，B组）的患者牙弓形态从T1到T2发生了变化，但在T3时复发为T1的形态。24.5%（n = 12，C组）的患者牙弓形态从T1到T2发生了变化，但在T3时保持相同形态。通过逻辑回归分析确定的有利于获得扩弓效果的特征为男性、处于牙齿发育未成熟阶段（侧切牙未完全萌出）以及存在侧方反牙合。使用双侧t检验（P < 0.05）分析不同时间点的尖牙间宽度、磨牙间宽度、牙弓长度以及切牙间点与连接尖牙的线之间的距离（尖牙间牙弓深度）。对于整个组，尖牙间宽度、磨牙间宽度以及尖牙间牙弓深度的增加具有统计学意义。使用方差分析对A、B、C组进行比较，但各组之间无显著差异。这种改良型哈斯矫治器能够增加混合牙列中上颌牙弓的横向尺寸。最合适的治疗时机似乎是在恒牙侧切牙萌出之前。
