Department of Adult Restorative Dentistry, University of Nebraska Medical Center College of Dentistry, Lincoln, Nebraska, USA.
Fourth-Year Dental Student, University of Nebraska Medical Center College of Dentistry, Lincoln, Nebraska, USA.
Clin Exp Dent Res. 2024 Feb;10(1):e827. doi: 10.1002/cre2.827.
Fabricating clear aligners by thermoforming three-dimensional printed dental models requires a high degree of accuracy. It is unknown whether model thickness affects the accuracy when used to thermoform aligners.
This research utilizes three-dimensional printed models made with differing wall thicknesses to determine its effect on their ability to withstand deformation during aligner fabrication.
A total of 50 models of different wall thickness (10 each of 0.5, 1.0, 1.5, 2.0 mm, and solid) were printed using model resin (Model V2, Formlabs) on a low-force stereolithography printer (Form 3B, Formlabs). Aligners were then fabricated using a thermal pressure forming machine (Biostar V, Great Lakes Dental Technologies) utilizing 25 s cycles to adapt 0.030″ acrylic sheets (Invisacryl, Great Lakes Dental Technologies), then removed from the models and sprayed with a contrast powder (Optispray, Dentsply Sirona) to aid in scanning with an intraoral scanner (CEREC Primescan, Dentsply Sirona). Each aligner's data was then compared to the original file used for printing with 3D comparison software (Geomagic Control X, 3D Systems).
The results show model thickness greater than or equal to 2.0 mm produced clinically acceptable results within the margin of error (0.3 mm). A total of 0.5 mm thickness failed to withstand thermal forming in 4 of the 10 trials. A total of 0.5 mm produced 27.56% of results in tolerance, 1.0 mm produced 75.66% of results in tolerance, 1.5 mm had 80.38% of results in tolerance, 86.82% of 2 mm models were in tolerance, and solid had 96.45% of results in tolerance.
Hollow models of thicknesses 2.0 mm and solid models produced clinically acceptable aligners while utilizing less resin per unit compared to solid models, thus being more cost effective, time efficient and eco-friendly. Therefore, a recommendation can be made to print hollow models with a shell thickness of greater than 2.0 mm for aligner fabrication.
通过热成型三维打印的牙科模型制作透明矫正器需要高度的准确性。目前尚不清楚模型厚度是否会影响矫正器制造过程中使用时的准确性。
本研究使用具有不同壁厚度的三维打印模型来确定其对模型在矫正器制造过程中抵抗变形能力的影响。
使用模型树脂（Formlabs 的 Model V2）在低力立体光刻打印机（Formlabs 的 Form 3B）上打印总共 50 个不同壁厚度的模型（每个厚度 10 个，分别为 0.5、1.0、1.5、2.0 毫米和实心）。然后使用热压力成型机（Great Lakes Dental Technologies 的 Biostar V）制造矫正器，使用 25 秒的循环将 0.030 英寸的丙烯酸片（Great Lakes Dental Technologies 的 Invisacryl）适应，然后从模型上取下并喷洒对比粉末（Dentsply Sirona 的 Optispray）以帮助用口腔内扫描仪（Dentsply Sirona 的 CEREC Primescan）进行扫描。然后使用 3D 比较软件（3D Systems 的 Geomagic Control X）比较每个矫正器的数据与其用于打印的原始文件。
结果表明，厚度大于或等于 2.0 毫米的模型在允许误差范围内（0.3 毫米）产生了可接受的临床结果。在总共 10 次试验中，有 4 次厚度为 0.5 毫米的模型未能承受热成型。总共 0.5 毫米的厚度有 27.56%的结果在公差范围内，1.0 毫米的厚度有 75.66%的结果在公差范围内，1.5 毫米的厚度有 80.38%的结果在公差范围内，86.82%的 2.0 毫米模型在公差范围内，实心模型有 96.45%的结果在公差范围内。
厚度为 2.0 毫米的空心模型和实心模型在使用较少的树脂比单位制造出可接受的矫正器的同时，因此更加经济高效、省时省力且环保。因此，建议为矫正器制造打印厚度大于 2.0 毫米的空心模型。
