A methodology for quantitative evaluation of root canal instrumentation using microcomputed tomography

AIM: The aim of this paper was to present an objective methodology for quantitative evaluation of root canal instrumentation using microcomputer tomography, together with developed software based on a constructed mathematical model. METHODOLOGY: A desktop X-ray micro-CT scanner (SkyScan 1072) was used to provide data sets of an extracted mandibular molar before and after instrumentation (ProFile 0.04 Taper instruments, Dentsply Maillefer, Ballaigues, Switzerland) that were stored for later use by software. A volume visualization package (T3D) was applied to obtain 3D renderings of the molar to illustrate the qualitative visualization capacity. Next, medical image volume fusion software was used to allow alignment of pre and post image volumes. Finally, software was developed to make quantitative measurements and to provide additional qualitative information on the registered image volumes. This procedure implemented a true 3D mathematical model for quantification of instrumentation effects. Using a local co-ordinate frame, perpendicular reslices were made at five different levels within the mesio-buccal canal to evaluate transportation and centring ability. RESULTS: At first accurate and detailed 3D renderings were obtained. The general and local canal shape before and after preparation could visually be examined in 360 degrees rotation. Numerical values were obtained for volume, volume changes and transportation. Centring ability was calculated by centring ratio and centre movement. CONCLUSIONS: This methodology is a new and objective way for quantitative evaluation of root canal instrumentation using microcomputer tomography and dedicated software.     

Rationale for the use of low-torque endodontic motors in root canal instrumentation

Abstract – Fracture of nickel‐titanium rotary files is an iatrogenic error which can seriously jeopardize root canal therapy. If a high‐torque motor is used, the instrument‐specific limit‐torque (fracture limit) is often exceeded, thus increasing the risk of intracanal failure. A possible solution to this problem is to use a low‐torque endodontic motor which operates below these values. If the torque is set just below the limit of elasticity for each instrument, the risk of fracture is likely to be markedly reduced. The purpose of this paper was to discuss mechanical properties of NiTi rotary instruments, the rationale for selecting low torque values, and to use clinically a new endodontic motor (step‐motor) which operates below the limit of elasticity of each rotary file. The step‐motor was found to be helpful in reducing the risk of instrument fracture. Irreversible material damage (plastic deformation) and instrument fracture were rarely seen. Low‐torque instrumentation also increased tactile sense and, consequently, mental awareness of rotary instrumentation.     

A cone-beam computed tomography study of root canal morphology of maxillary and mandibular premolars in a Turkish population

Aim. The aim of this study was to evaluate the root canal number and configuration of maxillary and mandibular premolar teeth by gender, intervals for decades, tooth position and unilateral or bilateral occurrence in a Turkish population using Cone Beam Computed Tomography(CBCT) scanning. Methodology. CBCT images of 5496 maxillary and mandibular premolars from 849 patients were evaluated. The following was evaluated in all the images: numbers of roots and root canals, the morphology of the root canal configuration according to the Vertucci classification, male–female differences in the tooth position and male–female differences in unilateral or bilateral occurrence. The reliability data were analyzed with a chi-square test. Results. The most prevalent root canal frequency was the two canals (86.2%) and type IV (76.9%) configuration for maxillary first premolar, one canal (59.7%) and type I (54.5%) canal configuration for second premolar. The incidence of one canal was higher in females and the occurrence of two or three canals was more common in males. The incidence of one canal was higher on the left side of maxillary premolars and the incidence of two canals was higher on the right side. Most mandibular first (93.5%) and second (98.5%) premolars had one canal. In general, females had one root canal of the mandibular premolar, whereas males had two or three canals. The type I configuration was most common and the incidence was higher on the right side. There were some differences found in the frequency distribution of the number of root canals and configuration of maxillary and mandibular premolar teeth according to intervals for decades. Conclusion. CBCT scanning provides comprehensive information about the root canal morphology of maxillary and mandibular premolar teeth. These data may help clinicians in root canal treatment of premolar teeth.     

锥束CT评价下颌第二恒磨牙牙根和根管解剖形态研究

目的:用锥束CT扫描评估下颌第二恒磨牙牙根和根管解剖形态。方法:收集305例锥束CT影像,分别记录病人的性别、牙位、牙根和根管的数目和形态,采用Vertucci分类法对根管构型进行分类描述。结果:在受检样本中,47.21%的下颌第二恒磨牙为融合根,C形根和C型根管的检出率均为41.64%。在两个根的下颌第二恒磨牙中,66.03%近中根管是Ⅳ型,92.31%的远中根管是I型。左、右侧下颌第二恒磨牙C形牙根和C型根管的发生率没有统计学差异(P>0.05),男性和女性的C形牙根和C型根管的发生率也没有统计学差异(P>0.05)。结论:中国西部人群中,下颌第二恒磨牙通常为双根或融合根,C形牙根和C型根管的发生率均较高。     

Evaluation of root canal morphology of maxillary premolars: a cone‐beam computed tomography study

The aim of this study was to evaluate the root canal configuration of maxillary premolars using cone‐beam computed tomography (CBCT). CBCT images of 999 maxillary premolars from a database were analysed to determine the frequency of the number of roots, root canals and Vertucci's classification. The associations among these variables were evaluated by Chi‐square test (P < 0.05). In the first premolars, 42.2% of single‐rooted teeth had a type II configuration, whereas 98.7% of 2‐rooted teeth showed type IV. In the second premolars, type I was the most prevalent (49.9%). The presence of two roots was more prevalent in first premolars, and the presence of one root was more prevalent in second premolars (P < 0.05). Male patients had a higher percentage of two roots compared with female patients (P < 0.05). Type IV and I was more prevalent in first and second premolars respectively (P < 0.05). There was a high frequency of 2‐rooted and single‐rooted teeth among maxillary first and second premolars respectively.     

CBCT法研究上颌第一磨牙根管形态

目的：探讨应用锥形束CT研究上颌第一磨牙牙根及根管形态的价值。方法选取70例患者83颗上颌第一磨牙的锥形束CT（cone beam computed tomogaphy,CBCT）影像,分析其牙根数目、根管数目及根管系统的解剖结构。参照Vertucci分类法对根管形态进行分类,统计近中颊根第二根管（the seconal mesiobuual canal, MB2）率。结果83颗上颌第一磨牙均为3个独立牙根,其中MB2的发生率为38.6%,近中颊根根管VertucciⅠ型（1?1）、Ⅳ型（2?2型）、Ⅱ型（2?1）、Ⅲ型（1?2?1）所占百分比分别为61.4%、18.1%、15.7%和4.8%。结论上颌第一磨牙根管系统复杂,CBCT影像可反映真实根管形态,为根管治疗提供参考。     

不同器械根管预备效果的实验研究

目的：比较临床常用扩锉器械的根管清理效果。方法：将60个离体牙随机分为6组，分别为空白对照组、K型钻组、K型钻和锉组、K型钻和H型锉组、K型锉组和超声扩锉组，采用逐步后退法预备根管。扫描电镜观察根管内壁。结果：根管壁碎屑面积比较，K型锉组＞K型钻组＞K型钻和锉组＞空白对照组＞K型钻和H型锉组＞超声扩锉组，且前3组与其余各组之间具有显著性差异（P＜0．05），而后3者之间无显著性差异（P＞0．05）。结论：超声扩锉与K型钻和H型锉效果最好；K型钻与K型锉交替使用次之；单纯扩或锉不能有效进行根管清理。建议临床采用K型钻和H型锉交替预备根管。     

显微CT在测量根管解剖结构中的方法应用

近年来,显微CT(micro-CT)在显示根管解剖结构中的微细变化,以及离体牙在根管预备前后结构变化中的应用,越来越受到关注。本文对micro-CT的测量方法进行综述。     

锥形束CT在下颌第二磨牙C形根管治疗前中后的应用

下颌第二磨牙C形根管存在根管变异和不规则峡区,容易造成根管清理不彻底和充填不足。锥形束CT(CBCT)可清晰地显示C形根管在矢状面、冠状面和横断面的解剖形态。CBCT空间分辨率高,图像清晰;可选择合适的视野,小视野图像更清晰;可以光盘形式最大限度的保存图像信息,方便临床医生在计算机上多层面、多方位的仔细观察;金属伪影少,辐射剂量低,扫描时间短;所显示下颌第二磨牙C形根管图像的矢状面、冠状面和横断面无前后重叠、无变形和无放大等情况,可为了解下颌第二磨牙C形根管形态提供清晰的三维影像。下颌第二磨牙C形根管预备的难度主要有相对独立的根管间有大量的副根管、交通支和根管弯曲,传统器械难以进入峡区;将显微镜和CBCT共同使用,可提高下颌第二磨牙C形根管的治疗效果。在根管预备前行CBCT检查,可提醒术者避免过度切削并防止侧穿。本文就CBCT在下颌第二磨牙C形根管治疗前中后的应用等研究进展作一综述。     

Symmetry of root anatomy and root canal morphology in maxillary premolars analyzed using cone-beam computed tomography

ObjectiveThis study aimed to use cone-beam computed tomography (CBCT) to evaluate the root anatomy and canal morphology of maxillary premolars in a Chinese population and determine their degree of bilateral symmetry.Design774 CBCT images were retrospectively analyzed, representing 1387 maxillary first premolars and 1403 second premolars. The number of roots and canals were recorded. The morphology of root canal systems was determined according to Vertucci’s classification. The symmetry of root and canal anatomies between maxillary contralateral premolars was further evaluated.ResultsThe most common anatomy of maxillary first and second premolars was one-rooted with two canals (58.0%) and one-rooted with one canal (50.3%), respectively. The typical canal morphology was type IV (42.7%) in maxillary first premolars and type I (50.3%) in maxillary second premolars. One-rooted maxillary premolars exhibited a higher variability in the canal morphology, compared to two-rooted or three-rooted teeth. Maxillary second premolars exhibited greater anatomic symmetry than first premolars. The root and canal numbers showed bilateral symmetry between 80.2% of maxillary first premolar pairs and 81.8% of second premolar pairs. Bilateral symmetry in both number and morphology of roots and canals was observed for 72.3% of maxillary first premolar pairs and 73.2% of second premolar pairs.ConclusionThe root anatomy and canal morphology of maxillary premolars in a Chinese population were quite diversified. Maxillary contralateral premolars demonstrated a high degree of symmetry in root and canal anatomies, which enables practitioners to better determine the nature of the root canal system during treatment of opposite homonymous teeth.     

Effect of root canal filling materials on dimensions of cone-beam computed tomography images

Objective

To evaluate the discrepancy of root canal filling (RCF) measurements obtained from original root specimens and cone-beam computed tomography (CBCT) images.

Material and Methods

Seventy-two human maxillary anterior teeth were prepared up to an ISO #50 K-File 1 mm short of the apical foramen. Thus, the teeth were randomly divided into 8 groups, according to the root canal filling material: Sealapex^®, Sealapex^®+gutta-percha points, Sealer 26^®, Sealer 26^®+gutta-percha points, AH PlusTM, AH PlusTM+gutta-percha points, Grossman Sealer, and Grossman Sealer+gutta-percha points. After root canal preparation and RCF, CBCT scans were acquired and the specimens were sectioned in axial, sagittal and coronal planes. The RCF measurements were obtained in different planes and thicknesses to determine the discrepancy between the original root specimens (using a digital caliper) and the CBCT images (using the scanner''s proprietary software). One-way analysis of variance and Tukey tests were used for statistical analyses. The significance level was set at α=5%.

Results

Measurements of the different endodontic filling materials were 9% to 100% greater on the CBCT images than on the original root specimens. Greater RCF dimensions were found when only sealers were used, with statistically significant difference among the groups.

Conclusions

RCF dimensions were greater on CBCT images than on the original root specimens, especially when only sealer was used.     

根管形态定量研究的方法

对于牙形态的研究早在20多年前就基本结束了,但在此基础上关于根管解剖形态的研究近10年来仍是一个热点,而且已由定性逐步向定量研究发展。下面拟就目前国内外用于根管形态定量研究的方法进行阐述。     

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目的利用锥形柬计算机断层扫描（CBCT）研究上颌第一磨牙近中颊根第二根管（MB2）发生率、根管解剖形态以及根管口位置分布。方法随机选取2011-2013年航天中心医院口腔科20～30岁患者CBCT影像160张（男80张、女80张）。平行近中颊根长轴平面观察其根管形态,并按照Vertucci分类统计。水平面观察根管口的位置,记录MB、MB2及腭根根管口间距离以及MB、MB2根管口分别到腭根根管口连线夹角,并比较不同性别间差异。结果本研究观察了279颗上颌第一磨牙,其中存在MB2牙齿233颗,检出率为83．5％,不同性别间差异无统计学意义（P〉0．05）。不同类型的根管出现概率不同,各类型出现率男女间无差异。MB与MB2根管口间距男性为（2．195±0．504）mm,女性为（1．966±0．419）mm,差异有统计学意义（P〈0．05）。结论上颌第一磨牙MB2发生率高,不同类型MB2发生概率不同,男性与女性之间无差异。MB与MB2根管口间距在两性之间存在统计学差异。     

根管封闭剂和锥形束CT拍摄参数对牙根纵裂诊断的影响

目的 研究根管封闭剂和锥形束CT(CBCT)拍摄参数对牙根纵裂(vertical root fractures,VRF)诊断的影响。方法 收集人前磨牙40颗,去冠,随机均分为4组:iRoot SP、AH Plus、载银锌介孔钙硅纳米粒子(Ag-Zn-MCSNs)和对照组。根管充填后制备VRF模型,然后将牙根置入人上颌前磨牙牙槽窝内,拍摄CBCT,视野(field of view,FOV)和体素分别为:12 cm×8 cm、0.30 mm;12 cm×8 cm、0.15 mm;8 cm×8 cm、0.15 mm;8 cm×8 cm、0.30 mm。由2名观察者对CBCT图像进行判读。结果 各实验组之间的准确性均无统计学差异(P＞0.05)。医师正确诊断根纵裂的部位均是在轴面冠1/3区。结论 不同根管封闭剂和CBCT拍摄参数诊断VRF的准确性无显著影响,建议应用CBCT诊断根充牙齿的VRF时,在满足诊断需求的前提下,选择较小FOV及较大的体素,以尽量降低辐射剂量。     

Comparative debridement study between hand and sonic instrumentation of the root canal

Abstract The cleaning efficiency of hand and sonic instrumentation with MM Sonic 3000 in 60 single-rooted human straight teeth was evaluated using light and scanning electron microscopy. The root canals were instrumented with K-type files and Shaper Sonic files, respectively, and manually irrigated with 1 % sodium hypochlorite. The results showed no statistically significant difference between hand and sonic instrumentation. In both groups a smear layer, untouched predentin and pulp tissue debris were generally observed.     

Mandibular mesial root canal morphology using micro‐computed tomography in a Brazilian population

To assess the root canal system morphology of mandibular molars by means of micro‐computed tomography, one hundred and four mandibular first molars were investigated and the following were evaluated: Vertucci's classification, the presence of lateral canals and the number of apical foramina. Mesial root canal surface area and volume were obtained by the CTAn and CTvol software. The type of root canal isthmi was classified applying the Hsu & Kim and Fan criteria. The most frequent root canal configuration was Vertucci type IV (46.2%). Lateral canals were observed in all root canal thirds and the average number of apical foramina was 3.15 ± 1.77. Regarding the presence of isthmus, Types I and II were the most prevalent, according to Hsu & Kim and Fan et al. criteria, respectively. Mesial root canals of mandibular molars showed high morphology variability.     

Flat-oval root canal preparation with self-adjusting file instrument: a micro-computed tomography study

Introduction

The aim of this study was to evaluate the root canal preparation in flat-oval canals treated with either rotary or self-adjusting file (SAF) by using micro-tomography analysis.

Methods

Forty mandibular incisors were scanned before and after root canal instrumentation with rotary instruments (n = 20) or SAF (n = 20). Changes in canal volume, surface area, and cross-sectional geometry were compared with preoperative values. Data were compared by independent sample t test and χ² test between groups and paired sample t test within the group (α = 0.05).

Results

Overall, area, perimeter, roundness, and major and minor diameters revealed no statistical difference between groups (P > .05). In the coronal third, percentage of prepared root canal walls and mean increases of volume and area were significantly higher with SAF (92.0%, 1.44 ± 0.49 mm³, 0.40 ± 0.14 mm², respectively) than rotary instrumentation (62.0%, 0.81 ± 0.45 mm³, 0.23 ± 0.15 mm², respectively) (P < .05). SAF removed dentin layer from all around the canal, whereas rotary instrumentation showed substantial untouched areas.

Conclusions

In the coronal third, mean increases of area and volume of the canal as well as the percentage of prepared walls were significantly higher with SAF than with rotary instrumentation. By using SAF instruments, flat-oval canals were homogenously and circumferentially prepared. The size of the SAF preparation in the apical third of the canal was equivalent to those prepared with #40 rotary file with a 0.02 taper.