State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, No. 14, 3rd Section of Renmin Nan Road, Chengdu, 610041, China.
BMC Oral Health. 2024 Nov 14;24(1):1379. doi: 10.1186/s12903-024-05090-z.
Virtual bracket removal (VBR) facilitates efficient retainer fabrication for fixed orthodontics in a digital workflow. This study is aimed at assessing the influence of the relative bracket base area (RBA), representing the proportion of the labial/buccal surface area intended for removal, on the surface reconstruction accuracy in the VBR technique.
196 teeth from seven resin dental models were included. The maximal bracket base surface area (MBA) was determined by the rectangular area extending to the lateral edges of the tooth labial/buccal surface. On each tooth, diverse RBA percentages (20-100% in 10% increments) of the MBA was removed, respectively. Following removal, the buccal surfaces of the teeth were digitally reconstructed. Subsequently, the root mean square (RMS) values, which represent the surface deviations between the reconstructed and original dentitions was calculated for each tooth. The obtained RMS values were compared within and among groups of different RBAs and compared with the clinically acceptable limit (CAL) of 0.05 mm.
As the RBA increased, there was a discernible trend of elevated RMS values, both for the overall dentition and each specific tooth type. Among the lower teeth, the molars consistently displayed the highest RMS values in almost all groups, with significantly higher mean/median RMS values compared to the lower incisors (P < 0.05), excluding the 0.2MBA group. Specifically, across all tooth types, the mean/median RMS values in groups with 20-80% MBA were significantly lower than CAL of 0.5 mm (P < 0.05). This trend persisted for all tooth types in the 0.9MBA group except the lower canines and molars.
The mean/median RMS values elevated as the RBA increased. VBR technique remains sufficiently accurate for retainer fabrication, provided that the RBA remains below 80% of the MBA for lower canines and molars and 90% for all the other tooth types. Notably, residual bonding materials should be considered in clinical use because they are also removed in VBR and thereby constitute a portion of RBA.
虚拟托槽去除（VBR）可在数字化工作流程中促进固定正畸保持器的高效制作。本研究旨在评估代表用于去除的唇/颊面面积比例的相对托槽基底面积（RBA）对 VBR 技术中表面重建准确性的影响。
纳入了七个树脂牙模型中的 196 颗牙齿。最大托槽基底表面积（MBA）通过延伸到牙唇/颊面侧缘的矩形区域确定。在每颗牙齿上，分别去除 MBA 的不同 RBA 百分比（20-100%，每次增加 10%）。去除后，牙齿的颊面被数字化重建。随后，计算了每颗牙齿的重建和原始牙列之间的表面偏差的均方根（RMS）值。在不同的 RBA 组内和组间比较了获得的 RMS 值，并与临床可接受限值（CAL）0.05 毫米进行了比较。
随着 RBA 的增加，整体牙列和每个特定牙齿类型的 RMS 值都呈现出明显的升高趋势。在较低的牙齿中，磨牙在几乎所有组中始终显示出最高的 RMS 值，与下切牙相比，平均值/中位数 RMS 值显著更高（P<0.05），除了 0.2MBA 组。具体而言，在所有牙齿类型中，MBA 为 20-80%的组的 RMS 值的平均值/中位数显著低于 0.5 毫米的 CAL（P<0.05）。这种趋势在除下尖牙和磨牙外的所有牙齿类型的 0.9MBA 组中均存在。
随着 RBA 的增加，RMS 值的平均值/中位数升高。只要 RBA 保持在下尖牙和磨牙的 MBA 的 80%以下，以及所有其他牙齿类型的 MBA 的 90%以下，VBR 技术仍然足够准确，可用于制作保持器。值得注意的是，在临床使用中应考虑残留的粘结材料，因为它们也在 VBR 中被去除，因此构成了 RBA 的一部分。
