Abstract：
OBJECTIVE: To evaluate the effects of repeated cut-off and rescan procedures on the trueness of three intraoral scanners (IOS).
METHODS: A tooth model (#16) with a standard class II cavity was prepared, and the complete-arch was scanned using a laboratory scanner (D2000, 3Shape A/S) to obtain a reference scan. Then the typodont was scanned with three IOSs (3Shape TRIOS 3, CEREC Omnicam, and Medit i500) under two rescanning strategies (full-cut and partial-cut), with varying numbers of repeated cut-off and rescanning procedures (0, 1, 3, 5, 7, or 10). The trueness discrepancy between the reference and experimental digital scan was estimated using root mean square (RMS) calculations. Three regions of interest were selected to represent the rescanning, identification, and non-rescan area. And the discrepancies were analyzed using a linear mixed model (α=0.05).
RESULTS: Cut-off and rescanning procedures significantly decreased the trueness of digital scans in all test conditions compared to the reference. However, no progressive increase in discrepancy was observed under any rescan conditions. Significant influences on trueness were found based on the IOS used, with the 3Shape system exhibiting lower RMS values. The partial-cut strategy showed lower RMS values compared to the full-cut strategy, albeit without statistical significance.
CONCLUSIONS: While repeated cut-off and rescanning procedures led to a decline in the quality of digital impressions, they did not result in discrepancy accumulation with repeated rescanning.
CONCLUSIONS: To ensure high scanning accuracy in dental practice, it is advisable to minimize the rescanning area when correcting imperfections in digital scans. Additionally, selecting an appropriate scanner can help mitigate the negative effects of the rescanning technique.
METHODS: A tooth model (#16) with a standard class II cavity was prepared, and the complete-arch was scanned using a laboratory scanner (D2000, 3Shape A/S) to obtain a reference scan. Then the typodont was scanned with three IOSs (3Shape TRIOS 3, CEREC Omnicam, and Medit i500) under two rescanning strategies (full-cut and partial-cut), with varying numbers of repeated cut-off and rescanning procedures (0, 1, 3, 5, 7, or 10). The trueness discrepancy between the reference and experimental digital scan was estimated using root mean square (RMS) calculations. Three regions of interest were selected to represent the rescanning, identification, and non-rescan area. And the discrepancies were analyzed using a linear mixed model (α=0.05).
RESULTS: Cut-off and rescanning procedures significantly decreased the trueness of digital scans in all test conditions compared to the reference. However, no progressive increase in discrepancy was observed under any rescan conditions. Significant influences on trueness were found based on the IOS used, with the 3Shape system exhibiting lower RMS values. The partial-cut strategy showed lower RMS values compared to the full-cut strategy, albeit without statistical significance.
CONCLUSIONS: While repeated cut-off and rescanning procedures led to a decline in the quality of digital impressions, they did not result in discrepancy accumulation with repeated rescanning.
CONCLUSIONS: To ensure high scanning accuracy in dental practice, it is advisable to minimize the rescanning area when correcting imperfections in digital scans. Additionally, selecting an appropriate scanner can help mitigate the negative effects of the rescanning technique.
摘要：
目的：评估重复切断和重新扫描程序对三种口内扫描仪（IOS）的真实性的影响。
方法：制备了具有标准II类腔的牙齿模型（＃16），并且使用实验室扫描仪(D2000,3ShapeA/S)扫描完整牙弓以获得参考扫描。然后用三个IOS（3ShapeTRIOS3，CERECOmnicam，和Mediti500)在两种重新扫描策略(全切和部分切)下，具有不同数量的重复切断和重新扫描程序(0、1、3、5、7或10)。使用均方根(RMS)计算来估计参考数字扫描与实验数字扫描之间的真实性差异。选择了三个感兴趣的区域来代表重新扫描，identification,和非重新扫描区域。并使用线性混合模型(α=0.05)分析差异。
结果：截止和重新扫描程序与参考相比，在所有测试条件下都显着降低了数字扫描的准确性。然而,在任何重新扫描条件下,均未观察到差异逐渐增加.根据使用的IOS，发现对真实性有重大影响，与3Shape系统表现出较低的RMS值。与全切策略相比，部分切策略显示出较低的RMS值，虽然没有统计学意义。
结论：虽然反复的切断和重新扫描程序导致数字印象质量下降，它们没有导致重复重新扫描的差异积累。
结论：为了确保牙科实践中的高扫描精度，当校正数字扫描中的缺陷时，建议最大限度地减少重新扫描区域。此外,选择合适的扫描仪可以帮助减轻重新扫描技术的负面影响。
方法：制备了具有标准II类腔的牙齿模型（＃16），并且使用实验室扫描仪(D2000,3ShapeA/S)扫描完整牙弓以获得参考扫描。然后用三个IOS（3ShapeTRIOS3，CERECOmnicam，和Mediti500)在两种重新扫描策略(全切和部分切)下，具有不同数量的重复切断和重新扫描程序(0、1、3、5、7或10)。使用均方根(RMS)计算来估计参考数字扫描与实验数字扫描之间的真实性差异。选择了三个感兴趣的区域来代表重新扫描，identification,和非重新扫描区域。并使用线性混合模型(α=0.05)分析差异。
结果：截止和重新扫描程序与参考相比，在所有测试条件下都显着降低了数字扫描的准确性。然而,在任何重新扫描条件下,均未观察到差异逐渐增加.根据使用的IOS，发现对真实性有重大影响，与3Shape系统表现出较低的RMS值。与全切策略相比，部分切策略显示出较低的RMS值，虽然没有统计学意义。
结论：虽然反复的切断和重新扫描程序导致数字印象质量下降，它们没有导致重复重新扫描的差异积累。
结论：为了确保牙科实践中的高扫描精度，当校正数字扫描中的缺陷时，建议最大限度地减少重新扫描区域。此外,选择合适的扫描仪可以帮助减轻重新扫描技术的负面影响。
