| Abstract: | 近幾年來隱形矯正蓬勃發展，過去主要是靠傾斜牙齒移動為主，所以只能 使用在輕度或中度困難的案例中， 隨著材料的發展，模片的改良及不同附件的 研發，讓醫師能更有效地控制牙齒的運動。因為裝置的包覆性，一般認為這對 前牙下壓移動是有優勢的，但目前關於這方面的生物力學研究較少，因此，本 研究目的以體外模型，於前牙角度正常情況下，模擬四顆外挺(extruded)的前牙 在不同角度下下壓(intrude)回正常角度之四顆門牙的移動變化。
研究使用 SCHEU 的 DURAN!T 的模片，分別在正常、唇傾(flare)及內傾
(retroclined)的前牙角度下，對四顆前牙進行下壓，透過量測牙冠水平及垂直的 移動量，以及牙齒角度的變化量來觀察牙齒移動。並將預測的前牙下壓量與實 際臨床下壓測量值進行比較。了解軟體設計的精確度可以幫助醫師未來預測過 度矯正的需要，從而減少中途修改的需要和治療時間。實驗先掃描前牙角度正 常的齒模，進行牙齒移動規劃，3D 列印序列移動的齒模，以模片壓印出矯正牙 套，於體外齒模進行各階段之裝載模片，以 3Shape trios scanner 掃描記錄各階 段的齒列影像，進行分析前牙之移動變化。 研究結果顯示:以正中門齒為例， 在 Normal 組，垂直向移動-1.992±0.322mm，水平向位移-0.362±0.139mm，角度 變化為 2.07±1.636°，結果比軟體設計的更下壓，而水平向略往外傾，角度也略 大(proclined)。前傾(Flare)組則是垂直向移動-1.212±-0.106 mm，水平向位移- 0.783±0.029 mm，角度變化為-2.468±0.293°，垂直及水平方向的位移和軟體設 計較為一致，但角度較外展(proclined)。Retroclined 組的垂直向移動-1.319±0.158 mm，水平向位移 0.28±0.15mm，角度變化為 1.992±0.308°，與軟體設計相比較 微外挺及內傾，但都還在可接受的誤差範圍，而角度卻有明顯偏小(retroclined)
結語:在未添加其他附件的情況下，做前牙下壓時會發現與 Flare 組的牙齒 移動與電腦軟體設計之差異最小，但其移動量也相對較其他兩組小。此外，研 究也發現在未添加附件下，模片對牙齒的頰舌向角度修正最不準確，因此建 議，臨床上先調整好上顎前牙頰舌向角度再進行下壓。
Clear aligner therapy(CAT) has been booming in the past few years. In the past, clear aligners were used to treat patients by tipping the teeth. Therefore, they can only
be used in mild or moderate malocclusion cases. With the development of material technology and the different types of attachments, the clinicians can more effectively control the movement of the teeth. Because the aligners cover all the surface of the teeth, it is generally considered that it is advantageous for intrusion. However, there are few biomechanical studies on this aspect. Therefore, this study uses an in vitro model to simulate the intrusion of four extruded anterior teeth under different angles.
In this study, SCHEU"s DURAN? foil was used to move the four anterior teeth
under normal, proclined, and retroclined inclination. We can observe the series of the tooth movement by measuring the the horizontal and vertical movement of the crown and also the inclination. Furthermore, this study also compare the virtual anterior teeth movement value created by 3Shape Ortho Analyzer with the actual clinical anterior teeth movement value. Understanding the accuracy of the software design can help clinicians predict the need for overcorrection in the future, thereby reducing the need for mid-course modifications and treatment time. We scanned the dental model with normal anterior inclination, planned the tooth movement, printed the series of dental models, thermoformed the aligners and carried out the experiment. Use 3Shape trios scanner to scan and record the dentition images of each stage to calculate, analyze, and compare the movement changes of the anterior teeth.
The research results show that for the Normal group, the vertical direction is more intruded than the software design, while the horizontal direction is slightly inclined outward and the angle is slightly larger (proclined). The Flare group results are rather more coincident with the software design in vertical and horizontal direction. While the angles are also slightly larger (proclined). The vertical direction of the Retroclined group is more extruded than the software design, while the horizontal direction is slightly inclined inward and the angle is slightly smaller (retroclined) |
