Department of Endodontics, School of Dentistry, State University of Rio de Janeiro (UERJ), Rio de Janeiro, Brazil.
Department of Endodontics, School of Dentistry, Grande Rio University (UNIGRANRIO), Rio de Janeiro, Brazil.
Int Endod J. 2022 Jan;55(1):113-123. doi: 10.1111/iej.13642. Epub 2021 Oct 21.
To evaluate the influence of traditional and conservative access cavity preparations on the remaining dentine thickness in the coronal third of mesial canals of extracted mandibular molars prepared with reciprocating instruments using micro-computed tomography as the analytical tool.
Seventy extracted mandibular molars were scanned at a pixel size of 19 μm. From this initial sample, 20 teeth were selected, pair-matched and distributed into two groups (n = 10) according to the access cavity preparation: traditional (TradAC) or conservative (ConsAC). The root canals were sequentially enlarged with Reciproc Blue R25 (size 25, 0.08v taper) and R40 (size 40, 0.06v taper) instruments. A new scan was performed and the postoperative stacks were coregistered with their respective preoperative datasets. A colour-coded cross sections of the roots were created and used to identify and measure the smallest dentine thickness related to both MB and ML canals at 1.0-mm intervals from the furcation level of up to 5 mm in the apical direction, in both mesial and distal aspects of the roots, before and after preparation. The statistical analyses were performed with paired-samples t-test, independent-samples Student T-test and Chi-Square test with a significance level of 5%.
At all levels of both groups, dentine thickness before preparation was greater than after preparation (p < .05). No difference in the percentage of dentine reduction was observed between TradAC and ConsAC groups (p > .05), but a significantly greater reduction was observed to the distal aspect of the roots (p < .05). After root canal preparation, dentine thinner than 0.5 mm was observed mostly along the distal aspect of the root (10% to 15%) of the MB and ML canals, with no influence of the access cavity type on its incidence to either mesial (X = 1.66; p = .2) or distal (X = 0.40; p = .5) directions. In the TradAC group, dentine thickness in most slices was greater than 1.0 mm after preparation (n = 124) whilst, in the ConsAC, it ranged from 0.5 to 1.0 mm (n = 136).
Traditional or conservative access cavity preparation in extracted mandibular molars did not influence the remaining dentine thickness in the coronal third of mesial canals enlarged with thermomechanically treated nickel-titanium reciprocating instruments.
使用微计算机断层扫描作为分析工具，评估传统和保守的入口腔预备对使用往复器械预备的下颌磨牙近中根管冠三分之一剩余牙本质厚度的影响。
对 70 颗下颌磨牙进行了 19μm 像素的扫描。从这个初始样本中，选择了 20 颗牙齿，根据入口腔预备的情况，配对并分为两组(n=10)：传统(TradAC)或保守(ConsAC)。用 Reciproc Blue R25(25 号，0.08v 锥度)和 R40(40 号，0.06v 锥度)器械依次扩大根管。进行了新的扫描，并将术后堆栈与各自的术前数据集进行了配准。创建了根的彩色编码横截面，并用于在根的近中和远中面，从分叉水平开始，在根尖方向上以 1.0mm 的间隔，识别和测量与 MB 和 ML 管相关的最小牙本质厚度，直到 5mm 处，在预备前后。使用配对样本 t 检验、独立样本学生 t 检验和卡方检验进行统计学分析，显著性水平为 5%。
在两组的所有水平，预备前的牙本质厚度均大于预备后的牙本质厚度(p<.05)。传统入口腔预备和保守入口腔预备组之间观察到的牙本质减少百分比无差异(p>.05)，但根的远中面观察到的牙本质减少明显更大(p<.05)。根管预备后，观察到 MB 和 ML 管的远中面牙本质厚度小于 0.5mm(10%至 15%)，入口腔类型对其发生率没有影响，无论是近中(X=1.66;p=.2)还是远中(X=0.40;p=.5)方向。在 TradAC 组中，预备后大多数切片的牙本质厚度大于 1.0mm(n=124)，而在 ConsAC 组中，牙本质厚度范围为 0.5 至 1.0mm(n=136)。
在使用热机械处理镍钛往复器械扩大的下颌磨牙近中根管冠三分之一，传统或保守的入口腔预备并不影响剩余牙本质厚度。
