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。     

Asymmetry of the root canal foramen

Deviation of the major apical foramen from the anatomical root apex is a recognized phenomenon. To determine the frequency, position and mean distance of the major apical foramen from the anatomical root apex, 230 roots of permanent teeth were examined stereomicroscopically and radiographically. Radiographic analysis was used to establish how accurate the conventional radiograph was in displaying such a deviation. The frequency of deviation of the major foramen, determined stereomicroscopically, was 76%, and depended on the type of teeth examined. Radiographic analysis of the same sample revealed 57% of root canals had asymmetry of the root canal foramen. Agreement of stereomicroscopic and radiographic findings was found to be 61%. The most frequent deviation of the major foramen was on the distal root surface (29%), but this was not statistically significant. The mean distance between the deviation of the major foramen and the anatomical root apex was 0.99 mm. The study indicates that the clinician should consider deviation of the foramen during root canal treatment, as the deviation could not easily be detected radiographically.     

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C形根管是一种根管形态的变异,主要特征是根管横截面形态呈弧形,好发于黄种人.C形根管的特殊形态给临床治疗如根管疏通、清理和充填带来了挑战,本文将详细介绍C形根管的形态、识别及处理方法.     

Anatomic evaluation of the retromolar canal by histologic and radiologic analyses

ObjectivesThe aim of this study was to identify the detailed anatomic morphology of the retromolar canal using histologic sections and cone-beam computed tomography (CBCT) images.Materials and methodsTwenty-two sides of the mandible obtained from cadavers and CBCT images of 72 patients (144 sides) were analyzed. All mandibles were prepared using conventional methods of tissue processing, stained with hematoxylin-eosin, and measured to elucidate the composition and dimensions of the retromolar canal with the aid of a light microscope. In addition, the prevalence, course, opening position, and distance of the retromolar canal from the second molar were measured on CBCT images.ResultsThe retromolar neurovascular bundle in the retromolar canal originated from the inferior alveolar neurovascular bundle, and the mean areas of the neurovascular bundle and each artery and nerve contained within it were 0.59, 0.07, and 0.05 mm², respectively. The mean horizontal and vertical diameters of the neurovascular bundle were 0.82 and 0.90 mm, respectively. The retromolar canal was detected more often on CBCT images (43.1%, 31 out of 72 patients). It mainly arose vertically (71.0%) from the mandibular canal and opened in the middle portion (57.9%) of the retromolar triangle at a mean distance of 13.13 mm from the second molar.ConclusionsThe retromolar canal is a normal anatomic structure that is relatively common and contains both a relatively large artery and a nerve. Clinicians need to pay closer attention to vascular problems as well as nerve damage when they are performing surgical procedures in the retromolar area.     

Clinical and anatomical study of retromolar foramen and canal.

PURPOSE: The retromolar canal is a rare anatomic variation of the mandible. The neurovascular content of the mandibular retromolar canal is very important for surgical procedures involving the retromolar area and there has been a lack of information on this subject. This study consists of anatomic research of the retromolar foramen and canal, planned after an impacted third molar tooth extraction operation in which we encountered a retromolar neurovascular bundle. MATERIALS AND METHODS: Eighty sides of 40 mandibles were evaluated and the presence of the retromolar foramen and its relation to the last teeth, the transverse and sagittal distances of the retromolar trigone, and the distance of the retromolar foramen to the last socket of the arch were measured. RESULTS: The neurovascular bundle includes striated muscle fibers, thin myelinated nerve fibers, numerous venules and a muscular artery. Of the 40 mandibles included in this study, retromolar foramens were found in 10 (25%). The presence of the retromolar foramen is not dependent on the last teeth of the arch. The dimensions of the retromolar trigone were measured and the presence of the retromolar foramen was found to be nonrelevant to the dimensions of the retromolar trigone. Retromolar foramen distance from the distal edge of the last socket of the arch was found to be 11.91 +/- 6.71 mm and 4.23 +/- 2.30 mm, respectively, from the second and third molars. CONCLUSIONS: This study therefore clearly establishes the incidence and importance of the retromolar canal. This study shows that the retromolar foramen and canal can be seen occasionally in routine dental surgery. Due to the neurovascular bundle passing through it, the retromolar canal and foramen must be kept in mind in all anesthetic and surgical approaches regarding the retromolar area and mandible.     

The position and topography of the apical canal constriction and apical foramen

Abstract. Two hundred and seventy extracted human teeth of unknown age were evaluated for apex to foramen and apex to constriction distances, in addition the topography of the apical portion of the root canal was studied under × 20 magnification. The mean A–F distance was 0.38 mm and the mean A–C distance 0.89 mm, although it must be stressed that a wide range of values was observed. Four distinct types of apical constriction were routinely found, whilst a proportion of canals were apparently blocked. The study confirms the view that it is impossible, with complete certainty, to establish the position of the apical canal constriction during root canal therapy, but indicates that a combination of methods might be more successful than reliance on one.     

牙槽上颌窦动脉骨孔的CBCT研究

目的 运用CBCT影像观察统计牙槽上颌窦动脉骨孔的发生率、直径,与剩余牙槽骨、上颌窦外侧壁的关系,为临床提供参考.方法 选择2016年1月2016年12月来首都医科大学附属北京口腔医院种植科要求行上颌后牙区种植手术的患者172名,拍摄CBCT测量其牙槽上颌窦动脉骨孔直径,上颌窦外侧壁的厚度,剩余牙槽嵴高度,骨孔下缘至剩余牙槽嵴顶间距,对各测量值进行统计分析.结果 入选172名患者中牙槽上颌窦动脉骨孔的发现率为53.3％(112/210).骨孔的平均直径为(1.27±0.36)mm;上颌窦外侧壁的厚度平均值为(1.81±0.55)mm;剩余牙槽嵴高度平均值为(7.85±3.09)mm;骨孔下缘距剩余牙槽嵴顶间距均值为(17.49±3.64)mm.经采用独立样本t检验,发现性别对骨孔直径影响差异无统计学意义(P>0.05).牙槽上颌窦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,牙槽上颌窦动脉骨孔直径与上颌窦外侧壁的厚度显著正相关.结论CBCT在检测牙槽上颌窦动脉具有较明显的优势,能为手术中避免血管出血提供参考.     

Variations of the bony canal in the mandibular ramus using cone-beam computed tomography

The location and configuration of the mandibular canal are important in surgical procedures involving the mandible. Previously, we reported that bifid mandibular canals could be classified into four types: retromolar, dental, forward, and bucco-lingual canals, using cone-beam computed tomography (CBCT). Herein we report three Japanese patients with a bony canal in the mandibular ramus, which was independent of the mandibular canal, using CBCT images. A CBCT unit with a flat panel detector and exposure volume of 102 mm in diameter and 102 mm in height was used. Two-dimensional (2D) and three-dimensional (3D) images in the mandibular ramus region were reconstructed using 3D visualization and measurement software packages. Three bony canals in two patients were considered to correspond to a temporal crest canal, which was raised from the mandibular notch, and reached the antero-inferior region of the coronoid process. One bony canal in one patient, ran bucco-lingually in the mandibular ramus. It is important for variations in the mandibular and bony canals to be carefully observed, by use of CBCT images, in surgical procedures involving the mandible.     

Study of the inferior alveolar canal and mental foramen on digital panoramic images

Objectives: To study the radiographic location of the mental foramen and appearance of the inferior alveolar canal and the relationship between image gray values and the clarity of inferior alveolar canal on the digital panoramic images and to evaluate if the histogram equalization of the digital image would improve the visualization of the inferior alveolar canal outline on the digital panoramic images in the mandible. Methods: Five hundred digital panoramic images were evaluated by two examiners using a specific inclusion criteria. Only the right side of the mandible was studied. Chi-square analyses were used for comparisons of distributions. Mean and median pixel values were analyzed separately with a one-way analysis of variance. Also, percentages were calculated to report the usefulness of the histogram equalization for visualization of canal. Results: Results show variation in location of mental foramen. Most frequent location of the mental foramen was reported as first and second premolar region. Chi-square analysis showed that the frequency of occurrence of the mental foramen was equally probable for any of the three locations. The study did not find significant usefulness of the gray values obtained from the histogram equalization in predicting the clarity of inferior alveolar canal outlines. Clinical significance: Knowing the normal relationship and the anatomical variation of the maxillofacial structures for each patient is important for surgical implant treatment planning to avoid future complications. It is also important to be familiar with the advantages and limitations of diagnostic aids available before making treatment planning decisions based on such findings. Keywords: Digital imaging, Panoramic, Inferior alveolar canal, Mental foramen. How to cite this article: Pria CM, Masood F, Beckerley JM, Carson RE. Study of the Inferior Alveolar Canal and Mental Foramen on Digital Panoramic Images. J Contemp Dent Pract 2011;12(4):265-271. Source of support: Nil Conflict of interest: None declared.     

Comparison of posterior alveolar canal location measured on computer tomography scan with cadaveric measurement of posterior superior alveolar foramen in Japanese samples

The aim of this study was to analyse anatomical characteristics of the most posterior alveolar canal (PAC) on computed tomography (CT) images and the posterior superior alveolar foramen (PSAF) physically identified in cadaveric samples, to avoid injuring the posterior superior alveolar artery (PSAA) during surgery in the maxillary tuberosity region. The study included 125 hemi-heads of 64 Japanese cadavers. Simple CT data of the maxillary bone region of the samples were obtained and analysed using measurement software. The alveolar crest (AC) and the PAC were identified to calculate the shortest distance between the AC and the PAC (AC-PAC). Then the samples were dissected to measure physically the shortest distance between the AC and the PSAF (AC-PSAF). The data were analysed statistically. The mean value and standard deviation were 20.7 ± 4.2 mm for AC-PAC and 20.7 ± 4.3 mm for AC-PSAF. The intraclass correlation coefficient between AC-PAC and AC-PSAF was 0.98. The CT-measured PAC locations were found to be almost identical to the PSAF positions identified physically in the samples. Preoperative CT localization of the PAC aids in avoiding injury to PSAA, while preoperative CT evaluation is important for each case due to significant individual variability in the anatomical PAC and PSAF locations.     

Analysis of radiologic factors in determining premolar root canal systems

OBJECTIVES: Certain tooth groups pose problems as to radiologic determination of root canal morphology. For example, the premolars may have superimposed roots that give the appearance of a single canal when 2 are actually present. This study examined the effect of X-ray tube inclination so as to visualize the complete root canal system in premolars. STUDY DESIGN: One hundred extracted premolars were divided into 4 groups of 25 teeth each: 1MxP (first maxillary premolar), 2MxP (second maxillary premolar), 1MdP (first mandibular premolar), and 2MdP (second mandibular premolar). A total of 10 radiographs were made of each tooth in the horizontal and vertical planes (horizontal angles of 0, 20, and 40 degrees, then vertical angles of 0, 15, and 30 degrees). Logistic regression analysis was used for the statistical analysis of the results--the dependent variable being the number of canals visualized. RESULTS: On varying the horizontal angle (20 and 40 degrees), the number of root canals observed in the case of 1MxP, 2MxP, and 1MdP coincided with the actual number of canals present. In the case of 2MdP, only the 40 degree horizontal angle correctly identified the number of canals regardless of the vertical angle (although only 4% had more than 1 canal). CONCLUSIONS: Varying the horizontal angle improved the visualization of additional (superimposed) canals in premolars. Changing of the vertical angle had no statistically significant influence except for the first mandibular premolars.     

The retromolar canal (foramen retromolare). Overview and case report

A 19-year old female patient was referred for removal of her wisdom teeth. The panoramic radiograph showed bilateral retromolar canals in the mandible. Since the retromolar canal is neglected in anatomical textbooks and is rarely documented in scientific publications, the case prompted us to perform further diagnostic examinations with informed consent by the patient. A limited cone beam computed tomography was made and, during the surgical removal of the patient's lower right wisdom tooth, a biopsy of the soft tissue bundle emerging from the retromolar foramen was taken. In accordance with the literature, the histology revealed myelinated nerve fibers, small arteries and venules. The limited data available in the literature about the retromolar canal report that this bony canal may convey an aberrant buccal nerve. In addition, sensory nerve fibers entering the retromolar canal from above and branching to the mandibular molars may evade a block anesthesia at the mandibular foramen. These rare anatomic features may explain why the elements of the retromolar canal account for failures of mandibular block anesthesia or postsurgical sensitivity changes in the supply area of the buccal nerve.     

Observation of the retromolar foramen and canal of the mandible: a CBCT and macroscopic study

Objectives  

The retromolar foramen (RMF) is an anatomical structure on the alveolar surface of the retromolar area. This foramen runs consecutive to the retromolar canal (RMC), which diverges from the mandibular canal. It is important to confirm the RMF and canal locations prior to surgical procedures, such as extraction of an impacted molar and bone harvesting as a donor site for bone graft surgery. This aim of this study was to investigate the RMF in Japanese cadaver mandibles using cone-beam computed tomography (CBCT) images and anatomical observations.     

The importance of apical patency and cleaning of the apical foramen on root canal preparation

The apical limit of root canal instrumentation has always been a matter of great controversy. Despite the large number of published studies on this subject, a consensus has not yet been reached. In fact, the recent discussion on apical patency and cleaning of the apical foramen, as well as the incorporation of these procedures to the endodontic treatment, seem to have raised even more polemics. It is likely that all this polemics has its roots in the lack of interrelation between the theoretical knowledge of pulp stump and periapical tissues and the real clinical practice. By addressing the most important aspects of this theme, this paper aims to present news concepts about the importance of apical patency and cleaning of the apical foramen during root canal preparation.     

Influence of apical foramen lateral opening and file size on cemental canal instrumentation

Since instrumentation of the apical foramen has been suggested for cleaning and disinfection of the cemental canal, selection of the file size and position of the apical foramen have challenging steps. This study analyzed the influence of apical foramen lateral opening and file size can exert on cemental canal instrumentation. Thirty-four human maxillary central incisors were divided in two groups: Group 1 (n=17), without flaring, and Group 2 (n=17), with flaring with LA Axxess burs. K-files of increasing diameters were progressively inserted into the canal until binding at the apical foramen was achieved and tips were visible and bonded with ethyl cyanoacrylate adhesive. Roots/files set were cross-sectioned 5 mm from the apex. Apices were examined by scanning electron microscopy at ×140 and digital images were captured. Data were analyzed statistically by Student's t test and Fisher's exact test at 5% significance level. SEM micrographs showed that 19 (56%) apical foramina emerged laterally to the root apex, whereas 15 (44%) coincided with it. Significantly more difficulty to reach the apical foramen was noted in Group 2. Results suggest that the larger the foraminal file size, the more difficult the apical foramen instrumentation may be in laterally emerged cemental canals.