Orthodontic Clinic, Public Dental Health, Växjö.
Department of Orthodontics, University of Malmö, Gävle.
Eur J Orthod. 2021 Apr 3;43(2):152-158. doi: 10.1093/ejo/cjaa077.
Retention of the maxillary anterior teeth is commonly recommended to maintain the teeth in their corrected positions. Both fixed and removable retention methods are used, but the certainty of evidence is low.
To evaluate post-treatment changes in irregularity of the maxillary six anterior teeth and single tooth contact point discrepancy (CPD) of three different retention methods.
Three-arm parallel group single-centre randomized controlled trial.
Ninety patients, 54 girls and 36 boys, were recruited to the study. The inclusion criteria were adolescent patients treated with fixed appliances at least in the maxilla. After gaining informed consent from the patient and their custodians, the patients were randomized to one of three groups: bonded retainer 13-23, bonded retainer 12-22, and removable vacuum-formed retainer (VFR) covering the maxillary teeth including the second molars. The randomization, prepared by an independent person, used blocks of 30. The primary outcomes were changes in single CPD and Little's irregularity index (LII) measured on digitalized three-dimensional study casts before and after 2-year retention. The study casts were anonymized before assessment and the changes were blinded for the assessor. Data were evaluated on an intention-to-treat basis. Thus, all randomized patients were incorporated into the final analysis.
The LII and CPDs increased slightly in all three groups without any statistically significant differences between the groups. The VFR group showed a small intercanine width increase and some more changes of canine rotations than in the other groups.
No harm was observed in any subjects and none of the patients needed retreatment.
The trial was a single-centre study and short-term changes were evaluated.
All three retention methods showed equally effective retention capacity and all the changes found in the three groups were small and considered clinically insignificant. Thus, the null hypothesis was confirmed. All three methods can be recommended.
NCT04616755.
保留上颌前牙通常被推荐用于保持牙齿在矫正后的位置。固定和可摘保持器都有使用，但证据确定性低。
评估三种不同保持方法对上颌六前牙的不规则性和单个牙接触点差异（CPD）的治疗后变化。
三臂平行分组单中心随机对照试验。
招募了 90 名患者，其中 54 名女孩和 36 名男孩，纳入标准为青少年患者，上颌至少接受固定矫治器治疗。在获得患者及其监护人的知情同意后，患者被随机分配到三个组之一：13-23 粘结保持器、12-22 粘结保持器和覆盖上颌牙齿（包括第二磨牙）的可摘真空成型保持器（VFR）。由独立人员准备的随机化使用 30 个块。主要结局是在 2 年保持后，通过数字化三维研究模型测量的单个 CPD 和 Little 不整度指数（LII）的变化。在评估之前，研究模型被匿名化，并且评估者对变化是盲法的。数据基于意向治疗进行评估。因此，所有随机分组的患者都被纳入最终分析。
所有三组的 LII 和 CPD 都略有增加，但组间无统计学差异。VFR 组的尖牙间宽度增加较小，犬牙旋转变化较多。
所有受试者均未观察到任何危害，也没有患者需要再次治疗。
该试验为单中心研究，仅评估了短期变化。
三种保持方法均具有同等有效的保持能力，三组中发现的所有变化都很小，被认为临床意义不大。因此，零假设得到证实。所有三种方法都可以推荐。
NCT04616755。
