Faculty of Dental Medicine, George Emil Palade University of Medicine, Pharmacy, Science, and Technology of Targu Mures, 38 Gh. Marinescu Str., 540142 Targu Mures, Romania.
Independent Researcher, SC Fusion Dental Clinic SRL, 520089 Sfantu Gheorghe, Romania.
Medicina (Kaunas). 2023 Jan 27;59(2):244. doi: 10.3390/medicina59020244.
: Appropriate tooth preparation is mandatory to obtain a perfect marginal fit of fixed restorations. The heavy chamfer is the most commonly used finish line, especially for minimally invasive tooth preparation. The aim of the study was to compare the width of the finish line obtained during tooth preparation performed by experienced (university lecturers) and inexperienced persons (dental students) in different working times and positions. : Forty left upper-second molars were prepared on the simulator by each participant, totalizing 160 prepared teeth. A new round-end tapered diamond was used to obtain the 0.5 mm width of the heavy chamfer. The prepared teeth were photographed using a Canon D5300 camera with a macro lens attached to a tripod. The measurements were made with the Image-Pro Insight software selecting the same eight reference points. From these points, perpendicular lines were drawn above the finish line to the axial walls and the distance between the chamfer's outer edge and the axial wall's inner edge was measured. GraphPad Instat and NCSS Dowson Edition software were used. The statistical significance was set at < 0.05. The mean (M) and standard deviation (SD) were calculated. The used tests: one sample t-test, ANOVA test, and Tukey-Kramer Multiple Comparisons Test. : Statistically significant differences were obtained according to the experience of the participant, preparation time, patient's position, and the chamfer width on the prepared tooth different surfaces. Daytime or weeklong tiredness and patient position do not affect the width of the heavy chamfer prepared by experienced and inexperienced persons. The experience and the operator's working position influence the width of the prepared finish line.
适当的牙体预备是获得固定修复体完美边缘适合的必要条件。深凹形边缘是最常用的边缘终止线，尤其适用于微创牙体预备。本研究的目的是比较有经验（大学讲师）和无经验（牙科学生）的操作人员在不同工作时间和位置时获得的边缘终止线的宽度。
四十颗左上第二磨牙在模拟器上由每位参与者预备，共计 160 颗预备牙。使用新的圆头锥形金刚石获得 0.5 毫米宽的深凹形边缘。使用佳能 D5300 相机和安装在三脚架上的微距镜头拍摄预备好的牙齿。使用 Image-Pro Insight 软件选择相同的八个参考点进行测量。从这些点，在边缘终止线上方的轴向壁上绘制垂直线，测量边缘倒角的外边缘和轴向壁的内边缘之间的距离。使用 GraphPad Instat 和 NCSS Dowson Edition 软件。统计显著性设置为 < 0.05。计算平均值（M）和标准差（SD）。使用的测试：一个样本 t 检验、方差分析和 Tukey-Kramer 多重比较检验。
根据参与者的经验、预备时间、患者的位置以及预备牙不同表面的边缘倒角宽度，均获得了统计学上的显著差异。白天或一周的疲劳和患者的位置不会影响有经验和无经验的操作人员预备的深凹形边缘的宽度。经验和操作人员的工作位置会影响预备边缘终止线的宽度。
