Abstract：
OBJECTIVE: To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors.
METHODS: Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student\'s t-test, with a statistical significance level of 5%.
RESULTS: Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008).
CONCLUSIONS: CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.
METHODS: Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student\'s t-test, with a statistical significance level of 5%.
RESULTS: Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008).
CONCLUSIONS: CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.
摘要：
目的：比较宫颈进入腔（CervAC）和传统进入腔（TradAC）对根管预备的影响，根管充填，下颌切牙的骨折阻力。
方法：首先使用Micro-CT设备扫描了20个最近摘除的完整下颌切牙。将标本进行解剖学匹配以创建两组(n=10)。使用双面分段金刚石盘在所有牙齿的颊侧形成楔形非龋齿宫颈病变（NCCL）。在第1组中，准备了TradAC，在第2组中，使用圆形钻石钻1012通过模拟的NCCL创建访问。用Rotate仪器15/0.04、20/0.04和25/0.04进行根管准备后，再次扫描牙齿并评估根管体积和表面积。静态体素，去除的牙齿组织的体积，和牙本质厚度。之后,使用单锥技术填充根管，用复合树脂修复牙齿，并随后重新扫描以计算填充材料和空隙的体积。然后，使用万能试验机对修复后的牙齿进行抗断裂性测试。组间统计比较采用Mann-Whitney检验或Student/t检验,具有5%的统计显著性水平。
结果：统计比较表明，在根管体积方面，组间没有显着差异，表面积,静态体素，去除牙本质，根管充填量,空隙的百分比，或抗断裂载荷(p>.05)。相反，与CervAC组相比，用TradAC制备的牙齿显示从牙冠去除的牙齿组织百分比明显更高（p=.001），并且牙髓腔中的填充材料残留物体积更大（p<.001）。在TradAC组中，仅在1级的根内侧观察到牙本质厚度的减少百分比显着降低（p=.008）。
结论：CervAC可以被认为是下颌切牙中存在NCCL的可行替代方法。
方法：首先使用Micro-CT设备扫描了20个最近摘除的完整下颌切牙。将标本进行解剖学匹配以创建两组(n=10)。使用双面分段金刚石盘在所有牙齿的颊侧形成楔形非龋齿宫颈病变（NCCL）。在第1组中，准备了TradAC，在第2组中，使用圆形钻石钻1012通过模拟的NCCL创建访问。用Rotate仪器15/0.04、20/0.04和25/0.04进行根管准备后，再次扫描牙齿并评估根管体积和表面积。静态体素，去除的牙齿组织的体积，和牙本质厚度。之后,使用单锥技术填充根管，用复合树脂修复牙齿，并随后重新扫描以计算填充材料和空隙的体积。然后，使用万能试验机对修复后的牙齿进行抗断裂性测试。组间统计比较采用Mann-Whitney检验或Student/t检验,具有5%的统计显著性水平。
结果：统计比较表明，在根管体积方面，组间没有显着差异，表面积,静态体素，去除牙本质，根管充填量,空隙的百分比，或抗断裂载荷(p>.05)。相反，与CervAC组相比，用TradAC制备的牙齿显示从牙冠去除的牙齿组织百分比明显更高（p=.001），并且牙髓腔中的填充材料残留物体积更大（p<.001）。在TradAC组中，仅在1级的根内侧观察到牙本质厚度的减少百分比显着降低（p=.008）。
结论：CervAC可以被认为是下颌切牙中存在NCCL的可行替代方法。
