Influence of scan setting selections on root canal visibility with cone beam CT

Objectives

The aim of this study was to assess the influence of scan setting selection, including field of view (FOV) ranging from small to large, number of projections and scan modes on the visibility of the root canal with cone beam CT (CBCT).

Methods

One human mandible cadaver was scanned with CBCT (Accuitomo 170; J Morita MPG Corp., Kyoto, Japan) using six different FOVs (4×4 cm, 6×6 cm, 8×8 cm, 10×10 cm, 14×10 cm and 17×12 cm) with either 360 or 180 projections in standard and high resolution. The right canine was selected for evaluation. Ten observers independently assessed the visibility of the canal space and overall image quality on a five-point scale.

Results

The results indicate that both selections of FOV and number of projections have significant influence on root canal visibility (p = 0.0001), whereas scan mode, whether standard or high resolution, was less relevant (p = 0.34).

Conclusions

The smallest FOV available should always be used for endodontic applications, and it is not recommended to reduce the number of projections to 180. Using the standard scan mode instead of high resolution does not negatively influence the visibility of the root canal space and is therefore recommended.     

Influence of the exomass on the detection of simulated root fracture in cone-beam CT – an ex-vivo study

Objectives:To evaluate the influence of exomass-related metal artefacts on the detection of simulated vertical root fracture (VRF) in cone-beam computed tomography (CBCT).Methods:20 teeth were endodontically instrumented and VRF was induced in half of them. All teeth were individually placed in an empty socket of a human mandible. Metallic materials were differently arranged in the exomass [zone outside of the field of view (FOV) but between the X-ray source and the receptor] and/or endomass (zone inside of the FOV), and CBCT scans were obtained. Four radiologists evaluated the presence of VRF using a 5-point scale. Sensitivity, specificity, and area under the receiver operating curve (AUC) were compared using ANOVA. Also, the tooth of interest was replaced with a tube filled with a radiopaque solution and all CBCT scans were repeated to analyse the data objectively. Mean grey and noise values were obtained from the tube and compared using ANOVA followed by Tukey’s test (α = 0.05).Results:Mean grey values were significantly lower and noise was significantly higher when metallic materials were present in the endomass or both the exomass and endomass. Sensitivity, specificity, and AUC were not influenced by the artefacts from the metallic materials irrespective of the arrangement condition.Conclusions:Exomass-related metal artefacts did not influence the diagnosis of simulated VRF in CBCT.     

Objective assessment of the combined effect of exomass-related- and motion artefacts in cone beam CT

Objectives:To assess quantitatively the combined effect of exomass-related- and motion artefacts on voxel value parameters in cone beam CT (CBCT).Methods:A cylindrical phantom was manufactured, containing 21 tubes filled with a radiopaque solution, allowing the inclusion of three titanium implants in the periphery to induce exomass-related artefacts. The phantom was mounted on a robot simulating 0.75-, 1.5-, and 3 mm movements (nodding/lateral rotation/tremor). CBCT images with/without exomass and with/without movements were acquired in duplicate in three units: Cranex 3Dx, Orthophos SL-3D, and X1 (with motion-artefact correction). A cylindrical volume of interest was defined in each tube and voxel value mean and standard deviation were assessed. For each CBCT volume, the 21 mean voxel values were averaged providing the overall mean voxel value (MVV), and the standard deviation (among the 21 values) was calculated providing overall voxel value inhomogeneity (VVI). The standard deviation from each of the 21 volumes-of-interest were averaged, providing overall image noise (IN). The effect of the diverse tested situations was inferred from a repeated-measures analysis of variance, followed by Sidak’s test (α = 0.05).Results:Overall, images acquired with exomass showed significantly (p ≤ 0.05) lower MVV, and higher VVI and IN. Motion artefacts aggravated exomass-related alterations. MVV and VVI were mostly affected by 3 mm nodding movements. Motion-artefact correction eliminated the deleterious effect of movement.Conclusions:CBCT voxel-value parameters are altered by exomass-related artefacts, and this finding is aggravated in the presence of motion artefacts. Motion-artefact correction effectively eliminated the deleterious impact of movement.     

Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal

Objectives

The aim of this study was to assess the reliability of four panoramic radiographic findings, both individually and in association, in predicting the absence of corticalization between the mandibular canal and the third molar on cone beam CT (CBCT) images.

Methods

The sample consisted of 72 individuals (142 mandibular third molars) who underwent pre-operative radiographic evaluation before extraction of impacted mandibular third molars. On panoramic radiographs, the most common signs of corticalization (darkening of roots, diversion of mandibular canal, narrowing of mandibular canal and interruption of white line) and the presence or absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were evaluated.

Results

Darkening of roots and interruption of white line associated with the absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were statistically significant, both as isolated findings (p = 0.0001 and p = 0.0006, respectively) and in association (p = 0.002). No statistically significant association was observed for the other panoramic radiographic findings, either individually or in association (p > 0.05).

Conclusion

Darkening of roots and interruption of white line observed on panoramic radiographs, both as isolated findings and in association, were effective in determining the risk relationship between the tooth roots and the mandibular canal, requiring three-dimensional evaluation of the case.     

一次性与多次根管填充术治疗牙髓炎临床对照研究

目的探讨一次性根管填充术治疗牙髓炎的方法和疗效,并与传统多次根管填充术进行对照分析。方法选取2013年10月至2015年10在大连市口腔医院口腔内科就诊的慢性牙髓炎患者126例(153颗患牙),按随机数字表分法将所有患者分为研究组和对照组。其中,研究组64例患者(76颗患牙)采取一次性根管填充术治疗,对照组62例患者(77颗患牙)采取多次根管填充术治疗。术后3个月对所有患者进行随访,并对两组患者治疗有效率进行对比。结果术后3个月,研究组60例患者(71颗牙)完成随访,有效率为97.2%(69/71);对照组60例患者(74颗牙)完成随访,有效率为85.1%(63/74);两组患者治疗总有效率比较,差异有统计学意义(P<0.05)。结论一次性根管填充术是治疗牙髓炎的有效方法,与多次根管填充术比较,具有治疗时间少、治疗次数少的优点。     

Widening of the spinal canal and dural ectasia in Marfan's syndrome: assessment by CT

We describe a method for diagnosing dural ectasia (DE) and spinal canal widening (SCW) using CT. We examined 23 patients with Marfan's syndrome (MFS), 17 with Ehlers-Danlos syndrome (EDS) and 29 normal subjects, using six axial slices at the level of the L1-S1 pedicles. Transverse diameters of the vertebral bodies, spinal canal and dural sac were measured and indices were defined to differentiate patients with DE and SCW from normal. Statistical significance was assessed using Student's t -test, χ ²-test and Pearson's correlation coefficient. DE and SCW occurred in 69.6 % and 60.9 % of cases of MFS and in 23.5 % and 35.3 % of EDS respectively. In MFS, prevalence was significantly higher than in the control group. DE was significantly more frequent in MFS than in EDS. A strong correlation existed between DE and SCW in MFS and the control group, but not in EDS. Our system enables quantitative assessment of SCW and DE. The latter is particularly important in subjects suspected of having MFS, in whom it is a common and characteristic sign. Received: 28 September 1998 Accepted: 16 March 1999     

Bifid mandibular canal: confirmation of limited cone beam CT findings by gross anatomical and histological investigations

Objectives

The aims of this study were (1) to assess the validity of limited cone beam CT (CBCT) in detecting the distribution of bifid mandibular canals in the retromolar region by comparing its findings with those of panoramic radiography and spiral CT imaging, and (2) to confirm the contents of such canals depicted on limited CBCT images by using gross anatomical and histological methods.

Methods

Bilateral bifid mandibular canals of a Japanese cadaver were investigated. The canals depicted on panoramic radiography, spiral CT and limited CBCT images were compared. Cross-sectional limited CBCT images of these canals were compared with gross anatomical sections of the mandible and their contents were confirmed histologically.

Results

The spiral CT and limited CBCT images showed the bilateral bifid mandibular canals in the retromolar region whereas the panoramic radiographs indicated the presence of only the left bifid mandibular canal. The canal distribution was more distinct in the limited CBCT images than in the spiral CT images and the cross-sectional limited CBCT images were consistent with the gross anatomical sections. Histologically, the canals contained several nerve bundles and arteries among which the largest nerve and artery were of a similar size.

Conclusion

Limited CBCT is valuable for assessing the distribution of bifid mandibular canals. It is clinically significant to accurately localize a bifid mandibular canal of the retromolar region because it contains a nerve bundle and artery.     

Evaluation of volumetric changes of teeth in a Brazilian population by using cone beam computed tomography

The purpose of this study was to test the usefulness of some morphometric parameters of the teeth in 5 different age groups through images of Cone Beam CT. 118 upper central incisors clinically acquired of 60 women and 58 men aged between 22 and 70 years were selected. The hard tissue volume and the pulp cavity volume of each tooth was obtained and computed by the software DentalSlice^® and the measures were assessed (pulp cavity volume, hard tissue volume, tooth volume and pulp cavity/tooth volume ratio). The pulp cavity volume and the pulp cavity/tooth volume ratio showed significant differences between age groups (p < 0.001). Linear regression analysis showed a coefficient of determination of 0.21 which suggests that there is a weak correlation between the pulp cavity/tooth volume ratio and age.     

显微超声技术治疗磨牙中上段不完全钙化根管的疗效分析

目的:评价显微超声技术在不完全钙化根管扩通治疗中的疗效。方法:采用显微超声技术对不完全钙化根管进行治疗,统计成功率。结果:70个不完全钙化根管中:44个为根管口,成功扩通43个,成功率为97.7%;20个为根中1/3处,成功扩通10个,成功率为50%;6个为根尖1/3,扩通1个,成功率为16.7%。3组间差异有统计学意义(P<0.01)。结论:显微超声技术为根管治疗提供了行之有效的方法,其中,根管口钙化疗效最好,根尖1/3处疗效最差。     

Cone beam CT image artefacts related to head motion simulated by a robot skull: visual characteristics and impact on image quality

Objectives:

The aim of this study was to assess artefacts and their impact on cone beam CT (CBCT) image quality (IQ) after head motion simulated by a robot skull.

Methods:

A fully dentate human skull incorporated into a robot simulated pre-determined patient movements. Ten head motion patterns were selected based on the movement of the C-arm of the CBCT units (no motion as reference). Three CBCT units were used [a three-dimensional eXam (K) (KaVo Dental GmbH, Biberach, Germany), a Promax 3D MAX (P) (Planmeca Oy, Helsinki, Finland) and a Scanora^® 3D (S) (Soredex Oy, Tuusula, Finland)]. Axial images were qualitatively assessed at three levels: mental foramen (MF), infraorbital foramen and supraorbital foramen, and artefacts characterized as stripe-like, double contours, unsharpness or ring-like. A 100 mm visual analogue scale (VAS) was used to quantitatively assess IQ. Cross-sectional images of the lower third molar and MF bilaterally were also evaluated by VAS. Four blinded examiners assessed the images.

Results:

For all units and motion patterns, stripe-like artefacts were the most common. The four observers agreed on the presence of at least one artefact type in 90% of the images. Axial images showed lower overall IQ after motion (VAS = 72.4 ± 24.0 mm) than reference images (VAS = 97.3 ± 2.6 mm). The most severe artefacts were seen at the MF level. For cross-sectional images, IQ was lowest after tremor. The mean IQ range was 74–89 and 57–90 for isolated (tilting, rotation and nodding) and combined (nodding + tilting and rotation + tilting) movements, respectively. IQ for MF was lower than for third molar for any movement except tremor.

Conclusions:

Head motion of any type resulted in artefacts in CBCT images. The impact on IQ depended on the region and level in the skull.     

高原藏族下颌切牙根管形态的研究

目的 :了解高原藏族下颌切牙根管形态 ,为下颌切牙的根管充填提供理论依据。方法 :采用拔除的下颌切牙经透明标本制备 ,在自然强光下观察根管的形态。结果 :74 4%为单根管口、单根尖孔 (1-1) ;6 4%为双根管口、双根尖孔 (2 -2 ) ;13 2 %为单根管口、双根管和单根尖孔 (1-2 -1) ;2 2 %为双根管口、单根尖孔 (2 -1) ;3 8%为单根管口、双根尖孔 (1-2 ) ;2 5 5%有侧、副根管。结论 :不同种族间的根管解剖形态确有差别     

Influence of cone beam CT enhancement filters on diagnosis ability of longitudinal root fractures

Objectives:

To determine whether cone beam CT (CBCT) enhancement filters influence the diagnosis of longitudinal root fractures.

Methods:

40 extracted human posterior teeth were endodontically prepared, and fractures with no separation of fragments were made in 20 teeth of this sample. The teeth were placed in a dry mandible and scanned using a Classic i-CAT® CBCT device (Imaging Sciences International, Inc., Hatfield, PA). Evaluations were performed with and without CBCT filters (Sharpen Mild, Sharpen Super Mild, S9, Sharpen, Sharpen 3 × 3, Angio Sharpen Medium 5 × 5, Angio Sharpen High 5 × 5 and Shadow 3 × 3) by three oral radiologists. Inter- and intraobserver agreement was calculated by the kappa test. Accuracy, sensitivity, specificity and positive and negative predictive values were determined. McNemar test was applied for agreement between all images vs the gold standard and original images vs images with filters (p < 0.05).

Results:

Means of intraobserver agreement ranged from good to excellent. Angio Sharpen Medium 5 × 5 filter obtained the highest positive predictive value (80.0%) and specificity value (76.5%). Angio Sharpen High 5 × 5 filter obtained the highest sensitivity (78.9%) and accuracy (77.5%) value. Negative predictive value was the highest (82.9%) for S9 filter. The McNemar test showed no statistically significant differences between images with and without CBCT filters (p > 0.05).

Conclusions:

Although no statistical differences was observed in the diagnosis of root fractures when using filters, these filters seem to improve diagnostic capacity for longitudinal root fractures. Further in vitro studies with endodontic-treated teeth and research in vivo should be considered.     

对比剂相关X线束硬化对CT值测量的影响

目的 探讨CT血管成像(CTA)对比剂所致X线束硬化对CT值测量的影响.方法 用26支注射针筒编号(1～26),1、4、7、23、20号针筒先分别抽取碘浓度为300 mg I/mL的对比剂1 mL、0.8 mL、0.6 mL、0.4 mL、0.2 mL,再抽取0.9％生理盐水配成20 mL含不同碘浓度的溶液,余针筒各抽取20 mL 0.9％生理盐水,作为实验组模拟颈动脉CTA检查.再用26支注射针筒编号并各自抽取20 mL 0.9％生理盐水,作为对照组模拟平扫.先后行CT扫描,检测、统计分析2组生理盐水CT值的差异.结果 实验组vs对照组生理盐水CT值的均数、最大值、最小值分别为(-0.139±10.322)HUvs (5.585±2.939) HU、14.6 HU vs 9.7 HU、-23.8HUvs-2.4HU,差异有统计学意义(t=2.695,P＜0.05).高浓度碘溶液周围针筒内生理盐水的CT测量值波动较大.结论 高浓度对比剂相关的X线束硬化,可使CT值的测量产生明显波动.     

超声荡洗对根管预备后疼痛及疗程的影响

目的探讨超声荡洗对根管预备后疼痛及疗程的影响。方法采用临床对照研究的方法,将40例牙髓根尖周病患者随机分为超声荡洗组和注射器冲洗组,观察两组根管预备后疼痛程度及疗程。结果对于慢性根尖周炎患者,超声荡洗组在根管预备后疼痛和患者的复诊次数上分别轻于及少于注射器冲洗组（P〈0．05）;对于慢性牙髓炎患者,两组在根管预备后疼痛和复诊次数上差异均无统计学意义（P〉0．05）。结论在根管预备过程中,采用超声荡洗,能够减轻慢性根尖周炎患者根管预备后出现的局部疼痛,同时减少患者根管治疗复诊次数。     

乳牙根尖周炎根管治疗疗效及对恒牙发育影响的临床观察

 对诊断为下颌乳磨牙根尖周炎行根管治疗的31名患儿,年龄3～7岁,共52颗患牙进行回顾性调查,结果表明:轻、中型乳牙根尖周炎行根管治疗术,无碍于继承恒牙胚的正常发育,重型乳牙根尖周炎,应拔除患牙,以便恒牙正常发育及替换.     

Influence of windowing and metal artefact reduction algorithms on the volumetric dimensions of five different high-density materials: a cone-beam CT study

Objective:To assess the influence of windowing and metal artefact reduction (MAR) algorithms on the volumetric dimensions of high-density materials using two CBCT systems.Methods:Four cylinders of amalgam, cobalt-chromium, gutta-percha, titanium and zirconium, were manufactured and their physical volumes (PV) were measured. A polymethyl methacrylate phantom containing the cylinders was submitted to CBCT acquisitions with Picasso Trio and OP300 units with their MAR enabled and disabled. The tomographic volume (TV) of all the cylinders was obtained by semi-automatic segmentation using two windowing adjustments: W1—large window width and upper window level; W2—narrow window width and low window level. Volumetric distortion was expressed as the difference between TV and PV. Statistics comprised intraclass correlation coefficient (ICC) and analysis of variance (ANOVA) for repeated measures with Tukey post hoc test (α = 5%).Results:The ICC values ​​indicated excellent reproducibility of TV. Gutta-percha and titanium resulted in the smallest volumetric distortion. Using W1 provided less volumetric distortion for almost all experimental conditions (p < 0.05). Activating MAR algorithm of Picasso Trio underestimated gutta-percha and titanium TV (p < 0.05) and was inefficient in significantly reducing the volumetric distortion of the other materials (p > 0.05). Disabling MAR algorithm of OP300 resulted in smaller volumetric distortion for almost all experimental conditions (p < 0.05).Conclusions:The TV of gutta-percha and titanium were closer to the PV. In general, the MAR algorithms of both systems were inefficient in significantly reducing the volumetric distortion of high-density materials. We encourage the use of large window width and upper window level to evaluate high-density materials.     

Effect of Er:YAG laser irradiation using SWEEPS and PIPS technique on dye penetration depth after root canal preparation

BackgroundThis study aimed to investigate the penetration depth of two different dyes after root canal preparation using PIPS and SWEEPS methods.Materials and methodsA total of 60 single-rooted human teeth which were extracted for periodontal reasons were collected and stored in the sterile saline until using in the study. The crowns of the teeth were cut such that the remaining piece was 12 mm long. The root canals were prepared. Teeth were divided randomly into two initial groups (n = 30): indocyanine green solution (ICG) and methylene blue solution. Then, these teeth were divided into final subgroups (n = 10): Er:YAG laser irradiation with PIPS(photon-induced photoacoustic streaming) technique, Er:YAG laser irradiation with SWEEPS(shock-wave enhanced emission photoacoustic streaming) technique, and no irradiation. The penetration depth measurements were done by the stereo microscope in three zones of each specimen.ResultsThe difference between ICG in the control group and PIPS and SWEEPS in the coronal area was not significant. In the middle section the difference between PIPS and the control group was marginally insignificant (P = 0.053). In the methylene blue group, PIPS had significantly higher penetration depth in the apical area compared to the control group (P = 0.004). In the middle section, both PIPS and SWEEPS showed significantly higher penetration than the control group.ConclusionAccording to the results of this study, the laser has the potential to increase the penetration of methylene blue. Root canal preparation with the PIPS technique can increase the dye penetration. However, the SWEEPS technique and the conventional method have a similar outcome in terms of dye penetration.     

吸烟人群肺部MDCT形态和容积量化评估及与肺功能的相关性研究

目的 分析吸烟人群肺部多排螺旋CT(MDCT)形态学特点,测量CT肺容积量化参数,研究二者与肺功能检查(PFT)指标的相关性.方法 选取59例吸烟者,其中14例为慢性阻塞性肺疾病(COPD)患者,另纳入39例不吸烟者作为对照组.所有受试者接受MDCT双气相扫描及PFT.分析并比较3组人群中与吸烟相关的11种肺部CT征象.测量肺气肿指数(EI)和平均肺密度(MLD).分析上述参数与PFT指标的相关性.结果 ①小叶中心型肺气肿、间隔旁型肺气肿、支气管扩张或管壁增厚的评分及发生率在3组间存在统计学差异(P均＜0.01).②吸烟COPD患者间隔旁型肺气肿与一氧化碳弥散量(DLCO)/肺泡容积(VA),支气管扩张或管壁增厚与DLCO实测值与预计值比值[DLCO SB(％P)]、DLCO与VA比值的实测值与预计值之比[DLCO/VA(％P)],EI与25％最大呼气量实测值与预计值的比值[MEF25％(％P)]、DLCO SB(％ p)、DLCO/VA(％P)均呈负相关.吸烟非COPD者小叶中心型肺气肿与第1秒用力呼气量与用力肺活量的比值(FEV1/FVC)、MEF25％(％P)、50％最大呼气量实测值与预计值的比值[MEF5％(％P)]、DLCO SB(％P)及DLCO/VA(％P),间隔旁型肺气肿与DLCO SB(％P)、DLCO/VA(％P),支气管扩张或管壁增厚与DLCO/VA(％P),EI与FEV1/FVC、MEF5％(％P)均呈负相关,MLD与FEV1(％P)、MEF25％ (％P)呈正相关.结论 MDCT可用于分析吸烟人群的肺部形态异常,其形态学特点及容积量化参数对肺功能有很好的预测价值.     

The effect of horizontal X-ray beam angulation on the detection of furcation defects of mandibular first molars in intraoral radiography

Objectives

The aim was to investigate the effect of changes in horizontal X-ray beam angulation in intraoral radiography on the detection accuracy of furcation defects in the mandibular first molar, and to examine the anatomical relationship between the roots and furcation area as a possible cause of changes in detectability.

Methods

Simulated furcation defects with various depths were created in five mandibular first molars. Intraoral radiographs were taken at various horizontal angulations of the projection beams. The diagnostic accuracies were determined based on receiver operating characteristic analysis. The geometric relationship that might influence the accuracy was investigated through use of a compact cone beam CT in 59 first molar areas.

Results

Although the horizontal angulations showing the highest accuracies were shifted mesially, no differences were found between the angles of −10° and 20°. The relationship between the roots and the furcation area was relevant to the range of angulations showing high detectabilities.

Conclusions

The angulations traditionally used for detecting proximal caries are also suitable for detecting furcation defects.     

Influence of CBCT parameters on the output of an automatic edge-detection-based endodontic segmentation

Objectives:

To determine the optimal CBCT settings for an automatic edge-detection-based endodontic segmentation procedure by assessing the accuracy of the root canal measurements.

Methods:

12 intact teeth with closed apexes were cut perpendicular to the root axis, at pre-determined levels to the reference plane (the first section made before acquisition). Acquisitions of each specimen were performed with Kodak 9000^® 3D (76 µm, 14 bits; Kodak Carestream Health, Trophy, France) by using different combinations of milliamperes and kilovolts. Three-dimensional images were displayed and root canals were segmented with the MeVisLab software (edge-detection-based method; MeVis Research, Bremen, Germany). Histological root canal sections were then digitized with a 0.5- to 1.0-µm resolution and compared with equivalent two-dimensional cone-beam reconstructions for each pair of settings using the Pearson correlation coefficient, regression analysis and Bland–Altman method for the canal area and Feret''s diameter. After a ranking process, a Wilcoxon paired test was carried out to compare the pair of settings.

Results:

The best pair of acquisition settings was 3.2 mA/60 kV. Significant differences were found between 3.2 mA/60 kV and other settings (p < 0.05) for the root canal area and for Feret''s diameter.

Conclusions:

The quantitative analyses of the root canal system with the edge-detection-based method could depend on acquisition parameters. Improvements in segmentation still need to be carried out to ensure the quality of the reconstructions when we have to deal with closer outlines and because of the low spatial resolution.