Efficacy of sonic and ultrasonic activation for removal of calcium hydroxide from mesial canals of mandibular molars: a microtomographic study

Background

The purpose of this study was to use micro-computed tomography (micro-CT) scanning to evaluate the efficacy of sonic and passive ultrasonic irrigation (PUI) on calcium hydroxide (Ca[OH]₂) removal and to measure the volume and percentage of Ca(OH)₂ remaining in the root canal system.

Methodology

The root canals of 46 extracted human mandibular molar teeth were prepared with rotary instruments and randomly assigned to two experimental groups (n = 40) as well as positive and negative controls (n = 6). In each experimental group, 20 teeth were assigned to each irrigation protocol, sonic or passive ultrasonic irrigation. All experimental teeth and the positive controls were filled with Ca(OH)₂, whereas the negative control teeth did not receive Ca(OH)₂. All teeth were scanned using micro-CT scanning to determine the dressing volume. After 7 days, the Ca(OH)₂ was removed in the experimental groups using rotary instrumentation only, and the teeth were again scanned using micro-CT scanning to calculate volume and percentage of Ca(OH)₂ removed. Positive control teeth were not subjected to rotary instrumentation. Experimental samples were then irrigated using either sonic or passive ultrasonic and the volume of remaining Ca(OH)₂ was calculated using micro-CT.

Results

Remnants of Ca(OH)₂ were found in all experimental groups. No Ca(OH)₂ was found in the negative controls, whereas a mean of 8.7 mm³ of Ca(OH)₂ was recorded in the positive controls. Rotary plus passive ultrasonic irrigation removed significantly more Ca(OH)₂ (85.7%) than rotary plus sonic irrigation (71.5%) (p < 0.001).

Conclusions

The combination of rotary instrumentation and passive ultrasonic activation for 3 periods of 20 seconds results in significantly lower amounts of Ca(OH)₂ remnants in the canal compared with sonic irrigation.     

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。     

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。     

口腔锥形束CT在下颌第二磨牙C形根管诊治中的应用

目的探讨口腔锥形束CT(cone-beam computed tomography,CBCT)在根管治疗中诊断治疗下颌第二磨牙C形根管的临床应用。方法选取初次根管治疗失败的下颌第二磨牙62颗,根尖片不能确定根管解剖形态以及可疑遗漏根管,患牙采用CBCT进行扫描三维重建。结果使用CBCT确定下颌第二磨牙中52颗为C形根管,C形根管发生率达83.87%,C形根管中28颗为C1型变异根管(53.84%),18颗为C2型变异根管(34.62%),6颗为C3型变异根管(11.54%)。52颗患牙除2颗因根管侧穿导致根管治疗失败外,其余50颗患牙通过热牙胶充填与垂直加压技术将软化的牙胶充入不规则的根管系统,达到严密充填根管,根管再治疗后患牙成功治疗的有50颗(96.15%),均无不适症状。CBCT在根管治疗中辅助定位变异根管,定位准确率较高。结论 CBCT影像精密度高,可从三维角度分析根管,在根管治疗中诊断治疗下颌第二磨牙C形根管具有临床指导意义。     

Anomalous mandibular premolars: a mandibular first premolar with three roots and a mandibular second premolar with a C‐shaped canal system

Aim To describe unusual variations in the root morphology and root canal systems of mandibular first and second premolar teeth extracted for orthodontic reasons. Summary Normally mandibular first and second premolar teeth have single roots with single canals. A 15‐year‐old patient presented for orthodontic treatment and two mandibular premolar teeth were examined post‐extraction. The mandibular first premolar exhibited three distinct, separate roots and the mandibular second premolar exhibited a C‐shaped root canal system. The coronal morphology of each of the mandibular premolars revealed dimensions and anatomy within normal limits. The incidence of a three‐rooted mandibular first premolar is approximately 0.2%. Key learning points ? Thorough clinical and radiographic interpretation is important in recognizing anomalous root and root canal systems. ? The most common forms of root and canal systems and its aberrations must be understood to realize variations from normal do occur. ? Successful root canal treatment requires an accurate diagnosis of the root canal system using all available aids. ? Value of microcomputed tomography in the study of anatomy ex vivo and cone‐beam tomography in clinical endodontics of complex premolar cases is increasing.     

下颌第二磨牙C形根管水平投照X线影像特点

目的探讨下颌第二磨牙C形根管水平投照x线影像特点。方法对77颗离体下颌第二磨牙进行水平投熙，两周后集中读片，将x线表现与离体牙牙根、根管形态和分型情况进行比较，总结离体牙C形根管水平投照x线影像特点。结果具C形根管的下颌第二磨牙的水平投照X线影像在牙根、髓腔、根管三方面有共同特点。牙根影像：①牙根影像呈单根，根尖锥形或结节状，中间有条索状或棒锤状X线低密度区；②似双根，根尖呈较宽的方圆形，“两根”之间由X线密度降低区连接，X线低密度区由根分歧处较窄渐向根尖区轻度增宽，“两根”尖部较圃钝。髓腔影像：髓腔深窄，髓室底近远中根管口距离近，一般不大于髓室底水平处牙根直径的1／3。根管影像：双根管或三根管影像，在根尖1／3汇合，或者有靠近趋势后又分开。除外粗大单根管影像。结论下颌第二磨牙C形根管X线影像具有一系列特点，对临床判断有一定帮助。     

Identification of root canals in molars by tuned-aperture computed tomography

AIM: To compare the tuned-aperture computed tomography system of imaging to conventional D-speed film for their ability to identify root canals in extracted human molars. METHODOLOGY: Thirteen maxillary and six mandibular human molars were mounted in acrylic blocks to simulate clinical conditions by surrounding the teeth with a radiodense structure. The teeth were then imaged with conventional D-speed film using a standard paralleling technique, and with a modified orthopantomograph OP100 machine using a Schick no. 2 size CCD sensor as the image receptor. The source images were registered and TACT slices were generated using TACT Workbench Software. Three observers were asked to identify the number of canals in the conventional film group and the TACT image group using specific criteria. Ground truth was established by cross-sectioning the teeth at the coronal, middle, and apical thirds of the roots and directly visualizing the root canal morphology. RESULTS: TACT imaging detected 36% of 4th canals in maxillary molars and 80% of third canals in mandibular molars. Conventional film detected 0% of fourth canals in maxillary molars and 0% of third canals in mandibular molars. The differences in canal detection between the two techniques were statistically significant (Wilcoxon matched pair sign rank test, P = 0.001). CONCLUSIONS: In this study, the TACT system of digital imaging was superior to conventional film in the detection of root canals in human molars and may be useful for the detection of root canals that will probably be missed upon conventional X-ray examination.