Branching of mandibular canal on cone beam computed tomography images

BackgroundMandibular neurovascular canal contents may be vulnerable to damage during mandibular surgical procedures. Greater knowledge of the location and configuration of the mandibular canal can help in the safe performance of these procedures in the dental clinic. Cross-sectional CBCT imaging is a good modality for studying the course, location, configuration and accessory branches of the mandibular canal. The aim of this study was to observe the branching of the mandibular canal at different segments of the mandible and mandibular tooth groups.MethodsCBCT images of 116 mandibular halves were included in this study. The presence of secondary branching of the mandibular canal in the ramus, retromolar area, molar and premolar teeth as well as the length, diameter and angle of these branches were observed.Resultssixty nine mandibular halves (59.5%), had a main canal with no branching, There were 36 IAC (31%) with one, 8 (6.9%) with two, 2 (1.7%) with three and 1(0.9%) with 5 accessory branches. Of these secondary branches, 16 (25.4%) were in the ramus, 16(25.4%) in the retromolar, and 31(49.2%) in the molar regions.ConclusionAdvanced cross-sectional imaging modalities especially CBCT is a suitable tool for observing anatomic characteristics of mandibular canal to preserve this vital structure in surgical procedures.     

The mandibular incisive canal and its anatomical relationships: A cone beam computed tomography study

Background

To avoid postoperative injuries in the interforaminal region, presence of the Mandibular Incisive Canal (MIC), its extension and canal positioning in relation to the cortical bone and alveolar process were investigated by cone beam computed tomography (CBCT).

Material and Methods

One hundred CBCT examinations obtained by means of the i-CAT CBCT imaging system were analyzed in multiple-plane views (axial, panoramic and cross-sectional) and three-dimensional representations were performed using iCAT CBCT software. The MIC was evaluated for its presence, measurement and proximity to the buccal and lingual plates, alveolar process and inferior border of the mandible.

Results

The MIC was visible in all (100%) CBCT images. The mean length of MIC was 9.8 ± 3.8 mm. The distances between the canal and buccal plate, as well as between the canal and lingual plate of the alveolar bone were 4.62 ± 1.41 mm and 6.25 ± 2.03 mm, respectively. The distances from the canal to the alveolar process, and to the inferior border of the mandible were 10.25 ± 2.27 mm and 7.06 ± 2.95 mm, respectively.

Conclusions

Due to the high prevalence of MIC, its variation in length and distance up to the cortical bone, suggested that preoperative radiographic evaluation of the MIC must be carried out case-by-case using CBCT, which could clearly show the three-dimensional structure and adjacent structure of the MIC. Key words:Diagnosis, anatomy, cross-sectional, tomography.     

下颌管分支的锥形束CT影像学分析

目的 运用锥形束CT（CBCT）分析下颌管分支发生的概率及其类型。方法 选取拍摄CBCT影像的216例（女104 例,男112例）患者为研究对象,对CBCT的下颌管分支影像进行观测并进行分类。结果 216例（432侧）患者中,39例（18.06%）50侧（11.57%）观测到下颌管分支,其中女18例（17.31%）,男21例（18.75%）。下颌管分支分为4类,第Ⅰ类17侧（3.94%）,第Ⅱ类11侧（2.55%）,第Ⅲ类20侧（4.63%）,第Ⅳ类2侧（0.46%）。结论 CBCT对下颌管分支的检出率较高,口腔颌面外科医生在进行下颌手术时应注意下颌管分支这一解剖变异。     

Assessment of variations of the mandibular canal through cone beam computed tomography

The neurovascular bundle may be vulnerable during surgical procedures involving the mandible, especially when anatomical variations are present. Increased demand of implant surgeries, wider availability of three-dimensional exams, and lack of clear definitions in the literature indicate that features of anatomical variations should be revisited. The objective of the study was to evaluate features of anatomical variations related to mandibular canal (MC), such as bifid canals, anterior loop of mental nerve, and corticalization of MC. Additionally, bone trabeculation at the submandibular gland fossa region (SGF) was assessed and related to visibility of MC. Cone beam computed tomography exams from 100 patients (200 hemimandibles) were analyzed and the following parameters were registered: diameter and corticalization of MC; trabeculation in SGF region; presence of bifid MC, position of bifurcations, diameter, and direction of bifid canals; and measurement of anterior loops by two methods. Corticalization of the MC was observed in 59% of hemimandibles. In 23%, MC could be identified despite absence of corticalization. Diameter of MC was between 2.1 and 4 mm for nearly three quarters of the sample. In 80% of the sample trabeculation at the SGF was either decreased or not visible, and such cases showed correlation with absence of MC corticalization. Bifid MC affected 19% of the patients, mostly associated with additional mental foramina. Clinically significant anterior loop (>2 mm of anterior extension) was observed in 22–28%, depending on the method. Our findings, together with previously reported limitations of conventional exams, draw attention to the unpredictability related to anatomical variations in neurovascularization, showing the contribution of individual assessment through different views of three-dimensional imaging prior to surgical procedures in the mandible.     

Evaluation of the visibility and the course of the mandibular incisive canal and the lingual foramen using cone‐beam computed tomography

Objectives: To assess the visibility and the course of the incisive canal and the visibility and the location of the lingual foramen using cone‐beam computed tomography (CBCT). Methods: In total, 100 CBCT examinations of patients for preoperative planning were used for this study. The examinations were taken using the NewTom 3G CBCT unit, applying a standardized exposure protocol. Image reconstruction from the raw data was performed using the NewTom software. Three experts were asked to assess the visibility of the incisive canal using a four‐point rating scale. The position of the incisive canal was recorded in relation to the lower, buccal and lingual border of the mandible using the application provided by the CBCT software. Results: The incisive canal was definitely visible in 83.5% of the scans and the mean endpoint was approximately 15 mm anterior to the mental foramen. The mean distance from the lower border of the mandible was 11.5 mm and its course was closer to the buccal border of the mandible in 87% of the scans. The lingual foramen was definitely visible in 81% of the scans. Conclusions: The high detection rate of the incisive canal and the lingual foramen in the anterior region of the mandible using CBCT indicates the potentional high preoperative value of CBCT scan for surgical procedures in the anterior mandible. To cite this article :
Makris N, Stamatakis H, Syriopoulos K, Tsiklakis K, van der Stelt PF. Evaluation of the visibility and the course of the mandibular incisive canal and the lingual foramen using cone‐beam computed tomography.
Clin. Oral Impl. Res. 21 , 2010; 766–771.
doi: 10.1111/j.1600‐0501.2009.01903.x     

健康成人下颌切牙管的锥形束CT测量分析

目的 利用锥形束CT测量下颌切牙管(mandibular incisive canal,MIC),了解其形态和特点,为临床提供参考.方法 观察2011年1月至2013年1月50名成人健康志愿者的锥形束CT图像,测量分析MIC的检出率、管径、长度及其与颌骨的关系.结果 在50例(100侧)锥形束CT图像中:MIC的检出率为100％(100/100),清晰率为71％(71/100);MIC的管径面积(唇舌径×垂直径)从起点至终点逐渐变小(左侧起点2.17 mm× 2.22 mm,终点0.82 mm× 0.92 mm;右侧起点2.14 mm×2.08 mm,终点0.87 mm×0.86 mm);MIC左右侧平均长度分别为17.84和17.73 mm;MIC在下颌骨唇舌向偏唇侧;在垂直方向MIC距下颌骨下缘较近,MIC到根尖的距离在尖牙最小.结论 锥形束CT对MIC有良好的检出率和清晰率;MIC在下颌骨的走行中偏向唇侧和下颌骨下缘.     

正常青年人下颌管全长三维走向及下颌骨形态的锥形束CT测量

目的采用锥形束CT（CBCT）分析正常青年人下颌管在下颌骨内的三维位置以及下颌骨的形态特征,为临床下颌骨手术提供解剖学依据。方法 对29例个别正常进行CBCT扫描,用InVivo 5软件对下颌骨进行三维重建,定位标记点,测量下颌骨形态以及下颌管在其内的三维走行。采用SPSS 17.0软件对测量值进行统计分析。结果 下颌管舌侧骨皮质厚度明显较颊侧骨皮质薄。下颌管到颊侧骨皮质的距离从近中到远中逐渐增加,到舌侧骨皮质、牙槽嵴顶的距离从近中到远中逐渐减小,到下颌下缘的距离在第一磨牙处最小,第二前磨牙处最大。下颌体截面高度、宽度、皮质骨厚度左右侧无统计学差异,从中线至远中,下颌体截面高度、舌侧下1/3皮质骨厚度逐渐减小,上截面宽度、唇/颊侧上1/3皮质骨厚度逐渐增大。部分测量项目性别间有统计学差异。结论下颌管入下颌孔后渐渐远离舌侧而向颊侧靠近,然后又逐渐远离偏向舌侧,但其总体走行还是靠近舌侧。男性下颌骨较女性更坚厚。CBCT能精确地显示下颌神经管的走行及其与周边结构的关系。     

下颌阻生第三磨牙与下颌管位置的曲面体层X线片和锥形束CT观察

目的 观察分析在曲面体层x线片上人群中下颌阻生第三磨牙(impacted mandibular third molar,IMTM)与下颌管位置关系的类型,并对二者关系密切的病例行锥形柬CT(conc beam computed tomography,CBCT)检查,了解二者实际位置关系.为临床制定IMTM拔除手术方案提供参考.方法 观察390例(645侧)曲面体层X线片,将IMTM与下颌管的位置关系的影像分为3种类型:①无接触类,二者影像无任何重叠或接触;②点状接触类,二者之间影像仅为点状接触;③部分重叠类,二者影像部分重叠或有较大范围接触.统计3种类型的构成比.曲面体层X线片显示IMTM与下颌管影像呈部分重叠或较大范围接触的部分病例行CBCT检查,观察曲面体层X线片IMTM与下颌管关系密切者中,IMTM实际突破下颌管壁所占的比例.结果 390例(645侧)IMTM的曲面体层X线片影像中,无接触类441侧(68.4%);点状接触类149侧(23.1%);部分重叠类55侧(8.5%).对31例(50侧)曲面体层X线片上显示IMTM与下颌管呈部分重叠或较大范围接触的CBCT检查发现,25侧(50%)IMTM突破下颌管壁.结论 ①曲面体层X线片可以排除90%以上IMTM与下颌管关系不密切的病例;②曲面体层X线片IMTM与下颌管影像呈部分重叠或较大范围接触表现的病例有必要行CBCT进一步检查.     

离体下颌前磨牙牙根和根管形态的锥形束CT研究

利用锥形束CT对190个离体下颌前磨牙进行扫描并选择不同方向的断层观察,按Vertucci’s分类法对根管系统进行记录。锥形束CT可以清晰显示其牙根和根管系统形态:下颌第一前磨牙根管系统变异较大,双根管率为22.8%。根管形态分别为Ⅰ型77.14%,Ⅱ型6.67%,Ⅳ型2.86%,Ⅴ型13.33%;下颌第一前磨牙的根面沟发生率较高(47/105),且此类型的下颌第一前磨牙常有双根管;下颌第二前磨牙的根管均为Ⅰ型单根管。     

利用CBCT对下颌骨切牙管的检出及对临床意义的探讨

目的 利用锥形束CT（CBCT）在活体上实现下颌切牙管（MIC）的检出和定位,并探讨其临床意义。 方法 从医院放射科CBCT数据库中,筛选符合标准的18～85岁个体。在研究对象的CBCT图像上,识别44～34根尖下方的MIC,确定可视性,测量MIC直径及到多个解剖标志的距离。 结果 第一前磨牙和尖牙区MIC可视性明显优于切牙区。下颌骨横断面上MIC多走行于垂直向中1/3段中线偏唇/颊侧。随着向正中联合部延展,MIC直径逐渐变小,绝大多数在切牙区变为不可见。 结论 MIC的临床意义可能没有想象中的重要。术前告知MIC损伤和神经功能障碍的风险是必需的,但更多是基于法律和伦理上的考虑。术前个性化三维图像检查和测量、以及术中尽量避开MIC中的血管神经束,仍是基本的临床要求。     

Evaluation of root canal morphology of mandibular premolars in a Saudi population using cone beam computed tomography: A retrospective study

Objective

To investigate the root canal morphology of mandibular first and second premolars using Cone-Beam Computed Tomography (CBCT) in a Saudi population.

Cross-sectional analysis of the mandibular lingual concavity using cone beam computed tomography

Objectives: To study the prevalence and the degree of lingual concavity in the edentulous first molar region from cone beam computed tomography (CBCT) scans of the mandibles. Material and methods: Qualified cross‐sectional images in mandibular first molar edentulous region taken from CBCT were selected. The mandible morphology 2 mm above the inferior alveolar canal (IAC) was classified into the convex (C), parallel (P) and undercut (U) type, based on the presence of lingual concavity and the shape of alveolar ridge. The prevalence of each group was determined. Subsequently, the lingual concavity characters, including the depth, the angulation and the vertical location were determined by the measurements of selected anatomic landmarks. Results: One hundred and three subjects (mean age 51 with a range of 23.7–70.4 years) were studied. The U type was the most prevalent, accounting for 66% of the study population. The mean undercut depth and angulation at the level 2 mm above IAC were on average 2.4 mm and 57.7°. The mean vertical distances from the most prominent point (P) of the lingual concavity to the cemento‐enamel junction of second premolar and the inferior border of the mandible were 11.7 and 14.9 mm, respectively. Conclusions: The anatomic location and the degree of the lingual concavity presented in this article add more information in implant treatment planning in the mandibular first molar edentulous region. To cite this article:
Chan H‐L, Brooks SL, Fu J‐H, Yeh C‐Y, Rudek I, Wang H‐L. Cross‐sectional analysis of the mandibular lingual concavity using cone beam computed tomography.
Clin. Oral Impl. Res. 22 , 2011; 201–206.
doi: 10.1111/j.1600‐0501.2010.02018.x     

Anatomic evaluation of the incisive canal with cone beam computed tomography and its relevance to surgical procedures in the mental region: a retrospective study in a Brazilian population

Background and objective

To evaluate the prevalence, location, length, diameter, and distances related to the incisive canal (IC) and the need for cone beam computed tomography (CBCT) as a complementary exam prior to surgery in the mental region.

Materials and methods

One hundred CBCT images from patients of both genders aged 27 to 73 years were evaluated. At every 3 mm, the diameter (DIAM) of the right and left ICs and their location, their distance to base of the jaw (BIC), the buccal (BAIC) and lingual (LAIC) aspects, and their length were measured.

Results

The 100 patients comprised 50 men (50%) and 50 women (50%). The IC was detected in 78 patients, more frequently in women (80%) than in men (76%). Measurements were taken in millimeters. The mean measurements for the two sides and for men and women combined were as follows: BIC?=?10.0, BAIC?=?4.0, LAIC?=?6.2, ICL?=?19.9, and DIAM?=?1.4.

Conclusions

The measurements show the need for care from professionals when performing intraosseous surgical procedures in the mental region. The distances between the IC and the references studied must be observed. Thus, CBCT becomes essential for surgical planning in the mental region.

Clinical relevance

The mental region of the mandible is considered a safe area to perform surgical procedures such as the placement of osseointegrated implants, orthognathic surgery, and the removal of bone grafts. However, this region includes important neurovascular structures that must be considered or else hemorrhage and neurologic disorders can be experienced.

     

锥形束CT与曲面断层在诊断下颌骨骨折中的比较研究

目的对比研究锥形束CT与曲面断层对下颌骨骨折的诊断特点及差异。方法收集2010年4月至2010年10月共27例因颌面部外伤行锥形束CT和曲面断层检查的患者的临床资料,比较两种方法对下颌骨不同部位骨折的诊断率。结果锥形束CT在下颌骨各部位的骨折诊断中均能明确观察骨折线及断端移位情况,而曲面断层存在漏诊现象,漏诊率为27.5%（11/40）,特别是髁突及颏部骨折,漏诊率分别为35.3%和27.3%。结论曲面断层检查存在漏诊的可能,特别是髁突或颏部骨折时,漏诊率更高。建议对下颌骨骨折应结合锥形束CT检查,以避免漏诊。同时,锥形束CT三维重建在帮助医生制定手术计划方面有很大优势和广泛应用前景。     

Assessment of simulated mandibular condyle bone lesions by cone beam computed tomography

There are many limitations to image acquisition, using conventional radiography, of the temporomandibular joint (TMJ) region. The Computed Tomography (CT) scan is a better option, due to its higher accuracy, for purposes of diagnosis, surgical planning and treatment of bone injuries. The aim of the present study was to analyze two protocols of cone beam computed tomography for the evaluation of simulated mandibular condyle bone lesions. Spherical lesions were simulated in 30 dry mandibular condyles, using dentist drills and drill bits sizes 1, 3 and 6. Each of the mandibular condyles was submitted to cone beam computed tomography (CBCT) using two protocols: 1) axial, coronal and sagittal multiplanar reconstruction (MPR); and 2) sagittal plus coronal slices throughout the longitudinal axis of the mandibular condyles. For these protocols, 2 observers analyzed the CBCT images independently, regarding the presence or not of injuries. Only one of the observers, however, performed on 2 different occasions. The results were compared to the gold standard, evaluating the percentage of agreement, degree of accuracy of CBCT protocols and observers' examination. The z test was used for the statistical analysis. The results showed there were no statistically significant differences between the 2 protocols. There was greater difficulty in the assessment of small-size simulated lesions (drill # 1). From the results of this study, it can be concluded that CBCT is an accurate tool for analyzing mandibular condyle bone lesions, with the MPR protocol showing slightly better results than the sagittal plus coronal slices throughout the longitudinal axis.