Alnahwi Hassan H, Donly Kevin J, Contreras Claudia I
Gen Dent. 2015 Nov-Dec;63(6):e1-4.
This study was designed to evaluate the amount of space loss (SL) caused by premature loss of primary second molars, determine whether the eruption status of permanent first molars is an important factor in the amount of SL, and evaluate the effectiveness of space maintainers (SMs) in SL prevention. SL associated with 100 prematurely extracted primary second molars was evaluated in 87 healthy patients. Teeth were divided into groups based on the use of SMs (36 with SM and 64 without SM). Bitewing and periapical radiographs taken before extraction and 6, 12, 24, 36, and 48 months after extraction were used to determine the amount of SL. Not every patient attended every recall appointment, so the sample size varied at different evaluation times. The most significant amount of SL occurred in the first 12 months after extraction. In patients who did not use an SM, at 6 months there was a mean SL of 2.12 mm (SD, 1.65 mm) and at 12 months there was a mean of 4.02 mm (SD, 1.65), with significantly more SL in the first 6 months (P < 0.001). There was no statistically significant difference in the amount of SL found at 12 and 24 months (P > 0.05). When patients without an SM were grouped by the eruption status of the permanent first molar, there was significantly more SL in the groups with unerupted first molars than there was in the groups with erupted first molars at both 6 months (P < 0.001) and 12 months (P < 0.05). At both 6 and 12 months, the amount of SL in patients who had an SM (n = 13 and n = 14, respectively) was not significantly different from the amount of SL in those who did not have an SM (n = 33 and n = 23, respectively). SMs should be placed as soon as possible following tooth extraction to prevent undue SL. Placement of an SM a year or more after extraction has minimal benefit, since most SL takes place within the first year. SL does occur even when SMs are used.
本研究旨在评估乳磨牙早失导致的间隙丧失（SL）量，确定恒牙第一磨牙的萌出状态是否为间隙丧失量的重要影响因素，并评估间隙保持器（SMs）在预防间隙丧失方面的有效性。对87例健康患者中与100颗早失乳磨牙相关的间隙丧失情况进行了评估。根据间隙保持器的使用情况将牙齿分为两组（36例使用间隙保持器，64例未使用间隙保持器）。拔牙前及拔牙后6、12、24、36和48个月拍摄的咬合翼片和根尖片用于确定间隙丧失量。并非每位患者都参加了每次复诊，因此在不同评估时间样本量有所变化。间隙丧失量最大的阶段出现在拔牙后的前12个月。在未使用间隙保持器的患者中，6个月时平均间隙丧失量为2.12 mm（标准差，1.65 mm），12个月时平均为4.02 mm（标准差，1.65），前6个月的间隙丧失量显著更多（P < 0.001）。12个月和24个月时的间隙丧失量无统计学显著差异（P > 0.05）。当未使用间隙保持器的患者按恒牙第一磨牙的萌出状态分组时，在6个月（P < 0.001）和12个月（P < 0.05）时，第一磨牙未萌出组的间隙丧失量均显著多于第一磨牙已萌出组。在6个月和12个月时，使用间隙保持器的患者（分别为n = 13和n = 14）的间隙丧失量与未使用间隙保持器的患者（分别为n = 33和n = 23）的间隙丧失量无显著差异。拔牙后应尽快放置间隙保持器以防止过度间隙丧失。拔牙后一年或更长时间放置间隙保持器益处甚微，因为大多数间隙丧失发生在第一年。即使使用间隙保持器也会出现间隙丧失。
