Evaluation of accessory mental foramen and accessory infraorbital foramen with cone-beam computed tomography in Turkish population

It was aimed to evaluate the frequency of accessory mental foramen (AMF) and accessory infraorbital foramen (AIOF) and analyse the correlation between these two foramina using cone-beam computed tomography (CBCT). The retrospective study reviewed the CBCT images of 1020 patients. The rates of AMF and AIOF were evaluated according to sex and age distributions. Correlations between the localizations of AMF and AIOF in the right and left jaws and the correlations between the occurrences of these foramina were evaluated. In the CBCT images of the 1020 patients, AMFs were detected in 48 patients, among which 14 were in the right half jaw, and 34 were in the left half jaw. AIOFs were detected in 143 patients, among which 65 were in the right half jaw, and 78 were in the left half jaw. Recognising and detecting AMF and AIOF with CBCT is important in terms of preventing complications that may occur in surgical procedures.     

Demonstration of the accessory mental foramen using rotational panoramic radiography compared with cone-beam computed tomography

Objective: Rotational panoramic radiography is routinely used in dental practice. It has not been clarified, however, whether an accessory mental foramen can be demonstrated using this technique. The visibility of accessory mental foramina on rotational panoramic radiographs was compared with those on para‐panoramic images reconstructed from cone‐beam computed tomographic (CBCT) images. Materials and methods: A total of 365 patients (130 males and 235 females) were retrospectively analyzed. Para‐panoramic images were reconstructed from CBCT images with the accessory mental foramen/foramina using three‐dimensional visualization and measurement software, and then the accessory mental foramen on rotational panoramic images was compared with that on para‐panoramic images. Results: A total of 37 accessory mental foramina were observed in 28 patients on CBCT images. The rate of being able to visualize the accessory mental foramen or bony canal between the point of bifurcation from the mandibular canal and the accessory mental foramen on rotational panoramic radiographs was 48.6% (18 of 37 accessory mental foramina). Conclusion: Approximately half of the accessory mental foramina‐positive CBCT images demonstrated the accessory mental foramen, or bony canal between the point of bifurcation from the mandibular canal and accessory mental foramen on rotational panoramic radiographs. To cite this article:
Naitoh M, Yoshida K, Nakahara K, Gotoh K, Ariji E. Demonstration of accessory mental foramen using rotational panoramic radiography compared with cone‐beam computed tomography.
Clin. Oral Impl. Res. xx , 2011; 000–000.     

四川成年人群下颌骨体副孔解剖位置的锥形束CT研究

目的 通过对下颌骨前部区域舌侧副孔数目与位置以及其与牙槽嵴顶距离的统计,得到不同年龄、性别受试者下颌骨副孔发生情况,为临床口腔手术安全操作提供参考依据.方法 选取200名符合条件的患者锥形束CT(cone-beam computed tomography,CBCT)影像资料,获取各副孔数目和位置及其到牙槽嵴顶的平均距离...     

Zygomaticofacial foramen location accuracy and reliability in cone-beam computed tomography

Objective. This study aimed to evaluate the possibility of detecting the zygomaticofacial foramen (ZFF) in cone-beam computed tomography (CBCT). Materials and methods. This study evaluated ZFFs in 151 macerated skulls (302 zygomatic bones, ZBs) by physical inspection, in which the presence and diameters of the ZFFs were determined. These data were compared with the CBCT images of the skulls to determine the accuracy of CBCT in detecting ZFFs. The diameters were measured by insertion of steel wires with known thicknesses into the ZFFs. The CBCT images were acquired by an i-CAT Classic® (International Imaging Sciences, Hatfield, PA) connected to a workstation (Model ITOX Midtower Workstation; Imaging Sciences International®) with a 20-inch Eizo monitor. The images were generated in coronal, sagittal and axial slices to evaluate the best tomographic plane for ZFF visualization. Results. The incidence of ZFF found by physical inspection was one foramen in 44% of ZBs (n = 133), two foramina in 28% (n = 86), three foramina in 8% (n = 24) and four foramina in 1% (n = 2). ZFF was absent in 19% (n = 57) of ZBs. The average diameter was 0.57 mm (± 0.27 mm). All foramina were observed in all tomography images. Conclusion. This preliminary study supports the conclusion that a CBCT scan has excellent accuracy in evaluating ZFFs.     

On cone-beam computed tomography artifacts induced by titanium implants

Objectives: To briefly review the mathematical background of beam‐hardening artifacts in cone‐beam computed tomography (CBCT)‐reconstruction and to investigate geometrical properties relevant for these reconstruction errors. By means of simulated and experimental results, beam‐hardening effects caused by titanium implants are evaluated. Materials and methods: The geometrical and physical properties of the acquisition process of the projections used for 3D reconstruction are investigated and their effects on the CBCT images in the presence of titanium implants are derived. Beam‐hardening effects are computed for a simplified polychromatic situation (three energy subsets of 80 and 110 kV) and compared with experimental results from a hard‐plaster phantom containing two ‘implants’ (pure titanium rods; 4 mm diameter) exposed in two CBCT machines. Results: Massive absorption within a typical implant body (diameter: 4 mm) was computed for the low‐energy subset of both energies (80 kV: 99.7%; 110 kV: 90.9%), whereas the high‐energy subsets are only marginally absorbed (80 kV: 14.8%; 110 kV: 11.3%). Accordingly, phantom data revealed drastically reduced gray values in artifact‐affected regions (3DAccuitomo: ?46% to ?51%) or (3DExam: ?55%) plus increased noise (+67% vs. +73%), when compared with unaffected regions. Conclusions: Our theoretical and experimental results prove massive beam‐hardening artifacts for a typical implant diameter and typical energies of up‐to‐date CBCT machines. Meaningful artifact reduction has to be based on more sophisticated mathematical modeling of the actual physical image acquisition process rather than on postprocessing of the erroneous results obtained from the rather crude reconstruction algorithms used presently. To cite this article:
Schulze RKW, Berndt D, d'Hoedt B. On cone‐beam computed tomography artifacts induced by titanium implants.
Clin. Oral Impl. Res. 21 , 2008; 100–107.     

口腔种植术前锥形束CT影像评估上颌窦状况

锥形束CT（CBCT）在种植术中具有非常重要的作用,通过CBCT可以了解种植术前术后的情况,判断种植体植入前植入床的基本条件,判断能否进行种植、种植植入方向、方法以及术后评估等。涉及到上颌窦的种植术应常规拍摄CBCT。本文通过临床实例介绍使用CBCT进行种植术前上颌窦分析评估及判断术后可能发生的改变。     

Characterisation of additional mental foramina through cone beam computed tomography

Variations in jaw bone neurovascularisation must be identified to decrease the potential risk for haemorrhages and neural disturbances during surgical procedures such as implant placement and orthognatic surgeries. The aim of this study is to characterise additional mental foramina (AMF) through cone beam computed tomography (CBCT) images, by describing their frequency, size, location and direction of their associated bony canals, as well as to assess their corresponding ipsilateral and contralateral mental foramina (MF). CBCT images from 285 patients were analysed. Prevalence of AMF was 9·4%. From 0 to 2 AMF were observed, with two bilateral cases. Two cases of unilateral absence of MF were registered. Patients presenting AMF did not differ significantly from those without AMF regarding gender, age or ethnicity. Diameters of AMF and their corresponding ipsilateral and contralateral MF were 1·9 mm (±0·7 mm), 3·8 mm (±0·6 mm) and 4·1 mm (±0·6 mm), respectively. Ratios between diameters of AMF and corresponding ipsilateral MF ranged between 0·24 and 0·99. Location of AMF was variable, with most cases located posteriorly, posterior-inferiorly, posterior-superiorly or anterior-superiorly to their respective MF. Significant anatomical variability regarding neurovascularisation was observed among patients and CBCT examinations presented as a valuable tool for individually assessing these anatomical features.     

中国西北地区人群恒牙牙根变异的锥束CT观察

目的:分析西北地区汉族人恒牙牙根变异的规律。方法:调取在西安市第四军医大学口腔医学院放射科接受锥束CT扫描病人的CT图像资料,病人共500人(男性246例,女性254)。观察并计算各类牙根变异的牙齿发生率和个体发生率。男女组间、双侧同名牙间率的比较采用卡方检验,左右侧不对称性采用Spearman等级相关性分析。结果:双根型下颌尖牙的发生率为0.63%(3/474人)。上颌第一前磨牙多根的发生率为30.28%(132/436人),下颌第一前磨牙Tomes根为13.45%(60/446人)。双侧上颌第二磨牙3根的发生率为57.48%(219/381人),下颌第一磨牙远舌根变异为31.98%(134/419人),下颌第二磨牙融合根为41.77%(165/395人)。除3根型下颌第一磨牙外,上述其他各项牙根变异性别差异均具有统计学意义(P<0.05)。结论:熟悉掌握汉人恒牙的牙根变异规律具有重要的临床价值。     

Tomographic evaluation of the mandibular nerve in the mental region and its surgical implications: a cross-sectional study

The aim of this study was to evaluate the prevalence and length of the anterior loop (AL) of the inferior alveolar nerve, nerve emergence from the mental foramen, and prevalence of sensory disorders after implant placement in the interforaminal region. Four hundred and fifty hemimandibles (225 patients) were evaluated using cone beam computed tomography and panoramic radiographs. Information on the presence of sensory disorders was obtained from the medical records. AL prevalence was 13.6% and mean AL length was 1.25 mm. The false-negative rate for the identification of the AL using panoramic radiography was 58.6%. Straight nerve emergence from the mental foramen was the most prevalent (62.7%), followed by anterior (21.8%) and posterior (15.6%) emergence. The incidence of sensory disorders was 4.4%, and 1.1% were related to the presence of the AL. When implants were placed within the planned distance of the mental foramen or further, 1.2% had sensory problems associated with the presence of the mandibular incisive canal. In cases of distances smaller than planned, 12.9% had sensory alterations. Only five (1.1%) had the AL, with a length between 0 and 4.5 mm. However, in four cases, the planned distance was respected and, even so, there was a sensory disorder. Posterior nerve emergence from the mental foramen was associated with a higher prevalence of AL.     

Anatomy of the accessory mental foramen in a Saudi subpopulation: A multicenter CBCT study

AimThe aim of this is to evaluate the prevalence and location of the accessory mental foramen (AMF) in a Saudi population using cone-beam computed tomography (CBCT).MethodologyCBCT data were retrieved from two dental facilities at two universities located in two different cities and filtered over a period of four years. The scans were aligned when the AMF was noticed, and then the size of both the AMF and mental foramen (MF), its location, and the distance from the AMF to the MF were recorded. The AMF measurements were compared between males and females and between the two sides of the mandible.ResultsIn total, 603 CBCT scans were investigated. The percentage of scans with an AMF was 9.95% (n = 60), and AMFs were almost equally distributed on both sides. Only four cases (0.66%) of a second AMF were detected among the scans. The MFs on both sides were significantly larger in males than in females (P > 0.05), but they showed no differences in the sizes of the AMFs. The AMFs were most commonly located inferior and posterior to the MF. The distance between the MF and AMF ranged from 2.32 to 5 mm.ConclusionsThe prevalence of the AMF in this Saudi population was 9.95%, and it was significantly more prevalent in males than in females. Its proximity to the MF makes it clinically important to conduct proper detailed planning prior to performing any procedure that might risk the vital structures.     

基于CBCT成像技术的颜面部不对称分类研究初探

目的　通过锥体束CT(cone beam computerized tomography,CBCT)资料分析颜面不对称患者颌骨的三维形态特征以及其颜面部不对称的发生部位。方法　对20例标准组及41例错牙合畸形患者分别使用CBCT采集颅面部数据,使用Dolphin11.0软件对骨组织进行三维重建,选择上下颌骨的部分标记点进行不对称系数的测量。结果　上颌骨不对称发生率为20.0%,下颌支不对称发生率为50.0%,下颌体不对称发生率为30.0%。安氏Ⅲ类组上颌骨不对称发生率为38.1%,下颌支不对称发生率为47.6%,下颌体不对称发生率为61.9%。安氏Ⅱ类组不对称发生率为20.0%,下颌支不对称发生率为50.0%,下颌体不对称发生率为35.0%。安氏Ⅲ类组中2例（9.5%）患者仅发生上颌不对称。结论　颜面不对称主要表现为下颌骨形态异常,上颌骨不对称通常伴随着下颌骨的不对称,安氏Ⅲ类患者颜面部不对称的发生率较对照组高。     

Effect of different intracanal posts and exposure parameters on detection of vertical root fractures by cone-beam computed tomography

This study evaluated the effect of different amperage values and voxel sizes of two CBCT scanners on VRF detection in the presence of different intracanal posts. After post-space preparation, VRFs were induced in half of the samples of 20 maxillary premolars. Five different intracanal posts were passively placed in each root canal. Samples were scanned using CS 9300 and Cranex3D with two different voxel sizes and amperage setting in each unit. The diagnostic sensitivity, specificity and accuracy were compared using the Mann–Whitney and Kruskal-Wallis tests (α = 0.05). Changes in amperage and voxel size did not affect the detection of VRFs (p ⟩ 0.05). The VRF detection accuracy was the highest in fibreglass and the lowest in nickel-chromium group. Changes in amperage and voxel size within assessed values do not seem to influence the detection of VRF whereas different intracanal post-materials have significant effect on VRF detection.     

锥形束CT对上牙槽后动脉骨孔的测量分析研究

目的 通过锥形束CT（CBCT）影像评估上牙槽后动脉骨孔位置、大小及与剩余牙槽骨的关系。方法 选择2011年4月-2012年9月前来南昌大学附属口腔医院种植科要求行上颌窦底提升手术和(或)上颌磨牙区种植手术,并且拍摄CBCT的患者116名,测量记录其上牙槽后动脉骨孔下缘至剩余牙槽嵴顶间距、上牙槽后动脉骨孔直径、剩余牙槽嵴高度,对各测量值进行统计分析。结果 入选116名患者中上牙槽后动脉骨孔的发现率为75.14%（133/177）;骨孔的平均直径为（0.96±0.29） mm;剩余牙槽嵴高度平均值为（7.14±3.64） mm;上牙槽后动脉骨孔下缘距剩余牙槽嵴顶间距均值为（17.92±5.68） mm。经采用独立样本t检验发现性别对骨孔直径影响差异有统计学意义（F= 0.187,P<0.05）;右侧和左侧骨孔间差异无统计学意义（F=0.295,P>0.05）。上牙槽后动脉骨孔下缘距牙槽嵴顶间距与剩余牙槽嵴高度显著正相关。结论 CBCT在发现上牙槽后动脉骨孔具有较明显的优势。     

Evaluation of voxel values in mandibular cancellous bone: relationship between cone-beam computed tomography and multislice helical computed tomography

Objective: Measurements of bone density in designed sites are important in presurgical imaging for dental implant treatment. However, the pixel or voxel values obtained from cone-beam computed tomography (CT) images are not absolute values. Hence, the relationship between voxel values obtained from cone-beam CT with a limited-volume exposure field and a flat panel detector and bone mineral densities (BMDs) obtained from multislice CT was evaluated in the mandible.
Material and methods: A total of 16 (four males and 12 females) patients who had undergone imaging for mandibular dental implant treatment using cone-beam CT with Alphard VEGA and multislice CT were enrolled in this investigation.
Cross-sectional images of cone-beam and multislice CT were reconstructed, and values of regions of interest (ROIs) in images were calculated.
Results: A high-level correlation between voxel values of cone-beam CT and BMDs of multislice CT was observed ( r =0.965).
Conclusion: It was suggested that voxel values of mandibular cancellous bone in cone-beam CT could be used to estimate bone density.     

Evidence supporting the use of cone-beam computed tomography in orthodontics

BackgroundThe authors conducted a systematic review of cone-beam computed tomography (CBCT) applications in orthodontics and evaluated the level of evidence to determine whether the use of CBCT is justified in orthodontics.Types of Studies ReviewedThe authors identified articles by searching the Cochrane Library, PubMed, MEDLINE, Embase, Scopus and Cumulative Index to Nursing and Allied Health Literature databases. They searched the articles' reference lists manually for additional articles and had no language limitations. They did not search the gray literature. Inclusion criteria were CBCT use in orthodontics and that the participants be human. The lowest level of evidence accepted for inclusion was a case series with five or more participants. The authors evaluated the studies' methodological quality according to 13 criteria related to study design, measurements and statistical analysis.ResultsThe authors identified 550 articles, and 50 met the inclusion criteria. Study topics included temporary anchorage devices, cephalometry, combined orthodontic and surgical treatment, airway measurements, root resorption and tooth impactions, and cleft lip and palate. The methodological quality averaged 53 percent (range, 15–77 percent) of the maximum score.Clinical ImplicationsThe authors found no high-quality evidence regarding the benefits of CBCT use in orthodontics. Limited evidence shows that CBCT offers better diagnostic potential, leads to better treatment planning or results in better treatment outcome than do conventional imaging modalities. Only the results of studies on airway diagnostics provided sound scientific data suggesting that CBCT use has added value. The additional radiation exposure should be weighed against possible benefits of CBCT, which have not been supported in the literature. In future studies, investigators should evaluate the effects of CBCT on treatment procedures, progression and outcome quantitatively.     

Detection of the Accessory Mental Foramina on Human Mandibles Using Cone-beam Computed Tomography: A Systematic Review and Meta-analysis

IntroductionThis study aimed to perform a systematic review and meta-analysis on accessory mental foramen (AMF) research using cone-beam computed tomographic (CBCT) imaging.MethodsA systematic review was performed in PubMed, Embase, Thomas Reuter's Web of Science, Scopus, and ScienceDirect databases according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement. Articles focusing on AMF prevalence and location using CBCT imaging were selected without language restrictions. Studies reporting pooled results only or presenting any pathology in the area surrounding the mental foramen (MF) were excluded. A meta-analysis using random effects was performed.ResultsThe present meta-analysis included a total of 46 articles involving 21,761 subjects. The overall pooled AMF prevalence was 7.87% (95% confidence interval [CI], 6.69–9.24) in subjects and 4.75% (95% CI, 3.79–5.95) in hemimandibles (n = 31,158). AMF presence was most commonly unilateral, reaching 90.15% (95% CI, 82.98–94.49). AMFs were significantly more frequent in right hemimandibles (χ² = 5.20, P < .05) and were most commonly located posterior and inferior to the MF. However, AMFs superior to the MF were also observed in 47.43% (95% CI, 38.45-56.58) of cases. The studies conducted over the last 3 years showed significantly higher AMF prevalence levels (χ² = 5.12, P < .05).ConclusionsOur meta-analysis demonstrates that AMF prevalence is considerable and should not be underestimated. AMFs are most frequently located in right hemimandibles. The presence of AMFs superior to the MF is frequent. Around 3% of people present superior AMFs. This fact puts those patients at greater risk for injury when performing periapical surgery in this area.