目的:评估促进具有不同粘合剂(复合材料)覆盖率的固定正畸保持器失效所需的力,并评估两种不同正畸保持器线的力传播的存在和程度。
方法:Ortho-FlexTech和Ortho-Care执行(0.0175英寸),每个15厘米长,被粘合在具有不同粘合剂表面直径的丙烯酸块上(2mm,3mm,4mm,和5毫米)。对样品(n=160)进行拉伸拉出测试,并记录脱粘力。使用两根不同的金属丝和4毫米粘合剂直径的固定固定器粘合在丙烯酸基上,类似于上颌牙弓(n=72)。在录制视频的同时,保持器在顶部被重新加载,直到出现故障的第一个迹象。提取并比较记录的各个帧。开发了力传播评分指数以量化载荷下力传递的程度。
结果:4毫米的粘合剂表面直径需要两个固定线的最高脱结力,与2毫米(P<.001;95%置信区间[CI]:8.69,21.69)和3毫米(P=.026;95%CI:0.60,13.59)相比差异显着。Ortho-CarePerformance的力传播得分明显较高。
结论:基于这种基于实验室的评估,应考虑在每颗牙齿上使用至少4毫米直径的复合材料覆盖来制造上颌固定固定器。与使用灵活的链条替代品相比,使用Ortho-CarePerform的力似乎更容易传播。这可能存在在末端处的应力累积的风险,具有在存在完整的固定保持器的情况下导致相关的不期望的牙齿移动的可能性。
To evaluate the force required to promote the failure of fixed orthodontic retainers with different adhesive (composite) coverage and to assess the presence and extent of force propagation with two different orthodontic retainer wires.
Ortho-FlexTech and Ortho-Care Perform (0.0175 inches), each of 15-cm length, were bonded on acrylic blocks with different adhesive surface diameters (2 mm, 3 mm, 4 mm, and 5 mm). The samples (n = 160) were subjected to a tensile pull-out test, and debonding force was recorded. Fixed retainers using two different wires and 4-mm adhesive diameter were bonded on acrylic bases resembling a maxillary dental arch (n = 72). The retainers were loaded occluso-apically until the first sign of failure while being video recorded. Individual frames of the recordings were extracted and compared. A force propagation scoring index was developed to quantify the extent of force transmission under load.
A 4-mm adhesive surface diameter required the highest debonding force for both retainer wires with significant differences compared with 2 mm (P < .001; 95% confidence interval [CI]: 8.69, 21.69) and 3 mm (P = .026; 95% CI: 0.60, 13.59). Force propagation scores were significantly higher for Ortho-Care Perform.
Based on this laboratory-based assessment, consideration should be given to the fabrication of maxillary fixed retainers using a minimum of 4-mm diameter composite coverage on each tooth. Force appeared to propagate more readily with Ortho-Care Perform than with a flexible chain alternative. This may risk stress accumulation at the terminal ends with potential for associated unwanted tooth movement in the presence of intact fixed retainers.