Zuckerman Offer, Katz Alexander, Pilo Raphael, Tamse Aviad, Fuss Zvi
The Maurice and Gabriela Goldshleger School of Dental Medicien, Tel Aviv Universisty, Tel Aviv, Israel.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003 Sep;96(3):351-5. doi: 10.1016/s1079-2104(02)91710-5.
We sought to measure the residual dentin thickness (RDT) in the mesial roots of mandibular molars after instrumentation with Lightspeed and Gates-Glidden rotary instruments. Study design Thirty extracted, untreated human mesial roots of mandibular molars were separated from the distal roots and embedded in clear polyester resin. The roots were cut horizontally at 1, 4, and 7 mm short of the anatomic apex. The diameter of each mesiobuccal canal was measured by using a stereo measuring microscope at each level in the buccolingual and mesiodistal directions. The dentin thickness was measured in each level in the mesial, distal, buccal, and lingual directions. Sections were reassembled with a muffle. The canals were enlarged to the working length with Lightspeed rotary instruments, of which the average size used was a No. 50 file. The coronal third was flared with No. 2 Gates-Glidden reamers. Slices were separated again, and the RDT and canal diameters were measured.
The minimal measured RDT after instrumentation at the 1-, 4-, and 7-mm levels was 0.70 +/- 0.28 mm, 1.04 +/- 0.18 mm, and 1.09 +/- 0.19 mm, respectively. The average diameter of the canals after instrumentation at the 1-, 4-, and 7-mm levels was 0.50 +/- 0.04 mm, 0.52 +/- 0.05 mm, and 0.74 +/- 0.08 mm, respectively. The canal diameter did not exceed one third of the root diameter at all levels.
Root canal preparation of mandibular mesial roots with Lightspeed instruments to No. 50 in the apical third and Gates-Glidden reamers to No. 2 in the coronal third does not significantly decrease the RDT.
我们试图测量使用LightSpeed和Gates - Glidden旋转器械进行根管预备后下颌磨牙近中根的剩余牙本质厚度（RDT）。
将30颗拔除的、未经处理的人下颌磨牙近中根与远中根分离，并嵌入透明聚酯树脂中。在距离解剖根尖1、4和7毫米处水平切断牙根。使用立体测量显微镜在每个水平的颊舌向和近远中向测量每个近中颊根管的直径。在近中、远中、颊侧和舌侧方向的每个水平测量牙本质厚度。切片用马弗炉重新组装。使用LightSpeed旋转器械将根管扩大至工作长度，所使用的平均型号为50号锉。冠部三分之一用2号Gates - Glidden扩孔钻扩开。再次分离切片，并测量RDT和根管直径。
在1毫米、4毫米和7毫米水平进行根管预备后测得的最小RDT分别为0.70±0.28毫米、1.04±0.18毫米和1.09±0.19毫米。在1毫米、4毫米和7毫米水平进行根管预备后根管的平均直径分别为0.50±0.04毫米、0.52±0.05毫米和0.74±0.08毫米。在所有水平根管直径均未超过根直径的三分之一。
使用LightSpeed器械将下颌近中根根尖三分之一预备至50号，冠部三分之一用2号Gates - Glidden扩孔钻进行根管预备，不会显著降低RDT。
