Madarati A A, Watts D C
Restorative Dental Sciences Department, College of Dentistry, Taibah University, Madinah, Saudi Arabia.
Endodontics & Operative Dentistry Department, Faculty of Dentistry, Aleppo University, Aleppo, Syria.
Clin Oral Investig. 2014 May;18(4):1135-1140. doi: 10.1007/s00784-013-1066-4. Epub 2013 Aug 8.
To investigate the temperature rise (TR) on the external root surface while preparing a staging platform, for removing intra-canal fractured instruments, using Gates Glidden (GG) drills.
Thirty extracted mandibular incisors were decoronated and 3-3.5 mm of F3 ProTaper files were fractured 3 mm from the most coronal end of the root. Roots were divided into three groups. GG drills were used in a size-2 to size-5 sequence to prepare the staging platform coronal to the fractured segment. They were rotated at three speeds according to the study groups: group A for 2,000 revolutions per minute (rpm); group B for 4,000 rpm; and group C for 8,000 rpm. Temperature changes were recorded at the proximal and buccal or lingual external root surfaces while preparing the staging platform. Data were analyzed using the paired sample T, one- and two-ways ANOVA tests at p ≤ 0.05.
Overall, TR at the proximal root surface (5.44 °C) was significantly higher than that at the buccal or lingual surface (3.25 °C) (p < 0.001). Generally, TR increased significantly as the size of GG drills or the revolution speed increased (p < 0.05). GG5 drills rotated at 8,000 rpm produced the highest TR (10.85 °C). There was no interaction effect of the GG drill size and the revolution speed on TR (p = 0.272).
The highest TR on the external root surface, associated with preparation of a staging platform and produced by using GG drills size-5 rotating at up to 8,000 rpm, was lower than the damaging threshold.
A staging platform can be performed by modified GG drills (no 2 to 5) rotating at 8,000 rpm without generating a hazardous TR.
研究使用盖茨-格利登（GG）钻制备台阶平台以取出根管内折断器械时，牙根外表面的温度升高情况。
选取30颗拔除的下颌切牙，去除牙冠，将F3 ProTaper锉在距牙根最冠方末端3mm处折断3 - 3.5mm。牙根分为三组。按照2号到5号的顺序使用GG钻在折断段冠方制备台阶平台。根据研究组，以三种速度旋转：A组每分钟2000转（rpm）；B组每分钟4000转；C组每分钟8000转。在制备台阶平台时，记录牙根近中面以及颊侧或舌侧外表面的温度变化。使用配对样本T检验、单因素和双因素方差分析对数据进行分析，p≤0.05。
总体而言，牙根近中面的温度升高（TR）（5.44℃）显著高于颊侧或舌侧表面（3.25℃）（p<0.001）。一般来说，随着GG钻尺寸或转速增加，TR显著升高（p<0.05）。以8000 rpm旋转的5号GG钻产生的TR最高（10.85℃）。GG钻尺寸和转速对TR没有交互作用（p = 0.272）。
使用5号GG钻以高达8000 rpm旋转制备台阶平台时，牙根外表面的最高TR低于损伤阈值。
使用改良的2号至5号GG钻以8000 rpm旋转可以制备台阶平台，而不会产生有害的TR。
