Development of dento-maxillofacial cone beam X-ray computed tomography system

We have developed a cone beam X-ray computed tomography (CT) system to make more accurate three-dimensional (3-D) images for diagnosis of dento-maxillofacial region. The developed system has sufficient spatial resolution, resolution of 3-D images and image distortion for diagnosis of dentomaxillofacial region.     

锥形束CT的特点及其在正畸专业中的应用

在正畸治疗中,X线检查对明确患者的错袷类型、制定错[牙合]畸形患者的矫治计划等具有重要的价值。长期以来,医生使用的曲面断层片和头颅侧位片,均为二维影像,且存在着重叠、图像放大等缺点。传统的扇形CT,因其占地面积大、设备价格高、操作复杂、射线量大、费用昂贵等因素,无法成为正畸患者常规的检查方法。近年来,随着锥形束CT（CBCT）的引入,对正畸患者的诊断和治疗,以及在医患沟通方面均带来了很大的帮助。本文就CBCT的起源和技术特点及其在正畸专业中的应用作一综述。     

Comparison of cone‐beam computed tomography and panoramic imaging in assessing the relationship between posterior maxillary tooth roots and the maxillary sinus: A systematic review

The objective of the present systematic review was to analyze research articles that compare the accuracy of panoramic imaging to cone‐beam computed tomography (CBCT) in assessing the relationship between posterior maxillary tooth roots and the maxillary sinus. A comprehensive literature search was conducted using various databases. Initial searching yielded 64 results, and after exclusion, five full‐text articles were eligible. All were cohort studies, and the CBCT and panoramic images were either obtained from a pre‐existing database or patients were recruited specifically for the study. Analysis showed that a panoramic image is sufficient for accurately detecting when the roots are at distinct distance from the sinus. However, if the roots are either laterally or medially projecting over the sinus and “just touching” it, panoramic images generally misinterpret this position, and instead make the root appear to be in the sinus. There were mixed results for when the root tip penetrates the sinus. Some studies claimed there was high agreeance between both modalities in this situation, while others had a low level of agreeance. In these situations, ordering a CBCT should be strongly considered to properly assess oral surgery risk with regard to maxillary posterior teeth.     

Detection accuracy of root fractures in cone‐beam computed tomography images: a systematic review and meta‐analysis

The aim of this review was to evaluate whether CBCT is reliable for the detection of root fractures in teeth without root fillings, and whether the voxel size has an impact on diagnostic accuracy. The studies published in PubMed, Web of Science, ScienceDirect, Cochrane Library, Embase, Scopus, CNKI and Wanfang up to May 2014 were the data source. Studies on nonroot filled teeth with the i‐CAT (n = 8) and 3D Accuitomo CBCT (n = 5) units were eventually selected. In the studies on i‐CAT, the pooled sensitivity was 0.83 and the pooled specificity was 0.91; in the 3D Accuitomo studies, the pooled sensitivity was 0.95 and pooled specificity was 0.96. The i‐CAT group comprised 5 voxel size subgroups and the 3D Accuitomo group contained 2 subgroups. For the i‐CAT group, there was a significant difference amongst the five subgroups (0.125, 0.2, 0.25, 0.3 and 0.4 mm; P = 0.000). Pairwise comparison revealed that 0.125 mm voxel subgroup was significantly different from those of 0.2, 0.25 and 0.3 mm voxel subgroups, but not from the 0.4 mm voxel subgroup. There were no significant differences amongst any other two subgroups (by α′ = 0.005). No significant difference was found between 0.08 mm and 0.125 mm voxel subgroups (P = 0.320) for the 3D Accuitomo group. The present review confirms the detection accuracy of root fractures in CBCT images, but does not support the concept that voxel size may play a role in improving the detection accuracy of root fractures in nonroot filled teeth.     

Evaluation of root canal morphology of maxillary premolars: a cone‐beam computed tomography study

The aim of this study was to evaluate the root canal configuration of maxillary premolars using cone‐beam computed tomography (CBCT). CBCT images of 999 maxillary premolars from a database were analysed to determine the frequency of the number of roots, root canals and Vertucci's classification. The associations among these variables were evaluated by Chi‐square test (P < 0.05). In the first premolars, 42.2% of single‐rooted teeth had a type II configuration, whereas 98.7% of 2‐rooted teeth showed type IV. In the second premolars, type I was the most prevalent (49.9%). The presence of two roots was more prevalent in first premolars, and the presence of one root was more prevalent in second premolars (P < 0.05). Male patients had a higher percentage of two roots compared with female patients (P < 0.05). Type IV and I was more prevalent in first and second premolars respectively (P < 0.05). There was a high frequency of 2‐rooted and single‐rooted teeth among maxillary first and second premolars respectively.     

Prospective study to estimate mandibular cancellous bone density using large‐volume cone‐beam computed tomography

Objective: Because pixel or voxel values obtained from cone‐beam computed tomography (CBCT) images are not absolute values, the bone density cannot be evaluated. Hence, the regression line between voxel values of CBCT and the bone mineral density (BMDs) of multislice CT (MSCT) was prospectively evaluated to investigate the mandibular cancellous bone density. Also, the usefulness of a reference bone block was evaluated on assessing a low mandibular bone density. Materials and methods: A total of 15 (two males and 13 females) patients who had undergone postoperative imaging for mandibular dental implant treatment with a bone graft using CBCT and MSCT were enrolled in this investigation. Voxel values of region of interests in CBCT were transformed to BMDs using a regression line from a previous study, and differences between BMDs obtained using CBCT and MSCT were calculated. Also, the voxel values of CBCT at the selected sites, in which the bone density was measured between 100 and 300 mg/cm³ of hydroxyapatite (HA) in MSCT, were assessed regarding whether they were higher or lower than the BMD of the reference bone block. Results: The mean overall difference was 38 mg/cm³ of HA. Thirty‐eight of the 45 sites (84%) were accurately assessed using the reference bone block. Conclusion: The usefulness of a regression line for BMD estimation in CBCT was prospectively confirmed in mandibular cancellous bone. Also, the reference bone block was useful to assess the low bone density of mandibular cancellous bone on CBCT with a large volume. To cite this article:
Naitoh M, Hirukawa A, Katsumata A, Ariji E. Prospective study to estimate mandibular cancellous bone density using large‐volume cone‐beam computed tomography.
Clin. Oral Impl. Res. xx , 2010; 1309–1313.
doi: 10.1111/j.1600‐0501.2010.01950.x     

Maxillary sinus unilateral aplasia as an incidental finding following cone‐beam computed (volumetric) tomography

This paper presents a case of maxillary sinus unilateral aplasia, an uncommon condition in adults, diagnosed as an incidental finding during cone‐beam computed tomography (CBCT) examination for an endodontic case analysis. The patient was referred to a specialist endodontic practice for management of an upper right central incisor tooth. A CBCT scan was performed. The images of the left maxillary sinus showed a total lack of pneumatisation, prompting the diagnosis of aplasia. The patient's otolaryngologist was made aware of the findings. Clinical evaluation of volumetric images should be performed by an adequately trained dentist or radiologist so the maximum amount of information is gathered for the patient. This requires a systematic approach to ensure that no relevant information is missed and should include the paranasal sinuses and other surrounding structures as incidental findings can be observed during CBCT analysis.