X-ray diagnosis of impacted upper canines in panoramic radiographs and computed tomographs

Ten orthodontists were asked to diagnose the number of impacted upper canines and the number of resorbed lateral and/or central incisor roots in 30 panoramic radiographs (P1) from 30 patients. In order to objectify these diagnoses, transversal CT images of all 30 patients were examined in addition. Addition of the recordings in the 30 patients revealed that the 10 orthodontists had diagnosed 350 impacted/displaced canines. On comparison of the P1 and CT results, the latter revealed that, in fact, 390 canines were impacted or displaced, not just 350. Addition of the recordings further showed that, based on P1, the investigators had diagnosed 73 resorptions in the 1,200 incisors examined. However, the CT showed 160 resorptions; this corresponds to a sensitivity value of 45.6%. The CT showed 1,040 incisors with no resorptions, whereas the investigators diagnosed only 925 teeth as not resorbed in the P1. The specificity was thus 88.9%. These results show that, due to their low reliability, panoramic radiographs are not an appropriate means of diagnosing resorptions in front teeth in connection with impacted canines.     

Image quality of two different mobile cone beam computed tomographs for maxillofacial surgery

PurposeWe evaluated two mobile cone beam computed tomographs (mCBCT) comparing image quality with respect to radiation dosage. Image quality was analyzed by using different scanning modes.Materials and methodsThe skulls of three human cadavers were scanned by use of conventional Computed Tomography (CT) as well as with two mobile cone beam computed tomographs (Siemens Arcadis Orbic 3D and Ziehm Vision Vario 3D). Six different acquisition modes with different radiation dosages were used. The axial views of all scans were evaluated by five medical doctors regarding image quality by identifying predefined anatomical structures of the skull. A five-point ranking scale was used. The inter-rater reliability was statistically depicted by Cohen’s Kappa coefficient. A Wilcoxon signed rank test was used to evaluate the rater’s results. For evaluating the signal-to-noise ratio (SNR) a Catphan 600 reference body with two different inlays was used.ResultsComparing the mCBCTs, the image quality of the Siemens Arcadis Orbic 3D in high-dosage mode received the best score (median: 2.27). The inter-rater reliability was fair (Kappa = ?0.030 to 0.328). The Wilcoxon test showed significant (p < 0.05) different median rating values in 18 out of 21 imaging modes. The SNR was higher (better) in the high-dosage modes.ConclusionIntra-operative 3D imaging by using mCBCT for maxillofacial surgery in low-dose mode acquisition is adequate in terms of signal-to-noise ratio and image quality. The image quality does not correlate in a linear manner with a higher radiation dosage. Surgeons using this technique should gather their own experience with the different acquisition modes.     

曲断片磨牙段线性测量放大率的比较

目的比较曲断片各磨牙区域的横向放大率和纵向放大率,评价横向及纵向线距测量的精确性。方法选择六个磨牙段完全萌出的成人干颅,用直径0.75mm 的不锈钢珠在各磨牙的三个横向平面(牙(牙合)面、牙颈部、根尖部)进行磨牙区域间标记,并构成牙冠部和牙根部两个纵向平面。拍摄曲断片,计算各横向线距和纵向线距曲断片放大率,进行统计分析。结果个体间磨牙区域横向放大率和纵向放大率差异都有显著性(P<0.05)。个体内第一磨牙后的各磨牙区域横向线距放大率在同一横向平面内无显著性差异,在不同平面间差异有显著性,颈部比牙(牙合)面小。个体内同一纵向平面各纵向线距放大率在上颌牙冠部差异无显著性而在牙根部差异有显著性。在下颁牙冠和牙根部都有显著性差异(P<0.05),有随着磨牙位置的后移纵向放大率均值逐渐减小的趋势。上颌在不同纵向平面间放大率差异有显著性,下颌无显著性。结论曲断片测量牙弓后部线距,个体之间无论横向还是纵向线距测量都没有可比性。个体内横向线距在同一平面第一磨牙之后的磨牙区域具有可比性。     

Dental maturity in children with chronic renal failure assessed from dental panoramic tomographs

Children with chronic renal failure are known to lag behind normal children for both height achievement and bone age. In the present study, dental maturity was assessed by scoring dental panoramic tomographs using two methods. The method of Dermirjian gave closer estimates of the chronological age than that of Leinonen. With the former method, dental maturity was found to be slightly delayed in children with chronic renal failure, although this was not statistically significant.     

Comparative dosimetry of dental cone beam computed tomography, panoramic radiography, and multislice computed tomography

Objectives  

The aim of this study was to compare the effective organ doses from cone beam computed tomography (CBCT), multislice computed tomography (MSCT), and panoramic radiography.     

颌骨侧位曲面断层片在上颌骨埋伏多生牙定位中的应用:25例报道

目的：探讨全景机颌骨侧位曲面断层片在上颌骨埋伏多生牙定位中的应用价值。方法：对25例上颌骨埋伏多生牙患者采用ORTHOPHS全景机行侧位曲面断层片，分析、判断埋伏多生牙的位置，采取不同的手术径路拔除埋伏多生牙。结果：(1)颌骨埋伏多生牙侧位曲面断层定位精确；(2)颌骨侧位曲面断层能显示牙弓与多生牙的关系：(3)颌骨侧位曲面断层片能显示多生牙的牙体及牙根的形态。结论：颌骨侧位曲面断层片对颌骨埋伏多生牙的定位具有重要价值。     

The accuracy of dental panoramic tomographs in determining the root morphology of mandibular third molar teeth before surgery

OBJECTIVE: The objective of this study was to assess the accuracy of dental panoramic tomograph (DPT) in the presurgical assessment of mandibular third molar teeth by correlating the radiologic interpretation with surgical findings. STUDY DESIGN: DPTs of 300 mandibular third molar teeth were assessed by 9 staff oral surgeons for root morphology and proximity to the inferior alveolar neurovascular bundle. Detailed records were made at surgery. RESULTS: The sensitivity and specificity for observation of root curvatures (+/-15%) were 29% and 94%, respectively. The sensitivity and specificity of determining an intimate relationship between the root and the neurovascular bundle were 66% and 74%, respectively. Kappa analysis demonstrated poor levels of agreement between radiologic interpretation and surgical findings when the number of roots was determined (0.191) and also when the roots were fused or separate (0.466). CONCLUSION: Using DPTs to assess mandibular third molar teeth before surgery gives poor diagnostic accuracy of anatomic form and structures.     

A survey of disease changes observed on dental panoramic tomographs taken of patients attending a periodontology clinic.

Dental panoramic tomographs (DPTs) were taken consecutively of 500 patients referred to a specialist periodontal department by general dental practitioners in order to assist in the diagnosis of the severity of the periodontal disease. Analysis of these DPTs showed 316 (63.2%) of these patients to have some form of dental abnormality unrelated to periodontal disease. The DPT was shown to be a valuable screening technique for clinical practice.     

Comparison of digital dental images yielded by digital dental casts,cone-beam computed tomography,and multislice computed tomography for measurement of dental area

Objectives

We investigated and compared the errors generated by multislice computed tomography (MSCT), cone-beam computed tomography (CBCT), and digital dental casts when used to provide digital data about dental structures.

Methods

Ten A20 skull models were scanned with MSCT and CBCT, and dental plaster cast models were optically scanned in three dimensions. The maxillary dental area was then compared. The distance between the three-dimensional scan data of the skull and each set of digital dental data were measured. Reference data were then overlapped with the experimental digital model using surface-based registration. The distance of errors was measured with the shortest distance measurement function. The distances between each experimental digital model and the reference scan data were measured, and error values were determined for all maxillary teeth and each tooth surface area. Errors were measured for all teeth from the central incisors to the second molar on both the left and right sides. Errors were measured from the mesial, distal, and labial surfaces and the tooth cusp tip area for each tooth.

Results

The digital dental casts had the smallest error (p < 0.001). The error in the digital dental casts (mean ± standard deviation) was 0.10 ± 0.12 mm. The CBCT error was 0.34 ± 0.38 mm, which was significantly greater than the MSCT error (0.19 ± 0.16 mm) (p < 0.001).

Conclusions

We recommend the use of digital dental casts with digital dental imaging for three-dimensional measurement of the dental area because this technique had the smallest errors.

     

Craniofacial computed tomography scanning: technology, applications and future trends

Author – Vannier MW Objectives – Craniofacial imaging in three dimensions depends on computed tomography (CT) and related technologies. This paper explains the state‐of‐the‐art for medical and dedicated craniofacial cone‐beam CT scanners. Method – Current medical CT scanners are surveyed, especially the recently announced 16 simultaneous slice models with subsecond source–detector rotation times and spiral/helical third generation geometry. The medical scanner technology is contrasted with dedicated low‐cost craniofacial cone‐beam CT scanners to delineate the relevant technologies and clarify the differences. Results – CT scanners performance in any task is determined by their detectors and reconstruction algorithm primarily and to a lesser extent by the X‐ray source, dose utilization, computational and display electronics, and software for post‐processing. Each of these components differs between medical and low‐cost cone‐beam scanners, and the differences are tabulated and explained. Conclusion – Low‐cost craniofacial CT scanners are significantly different from general purpose medical CT scanners, with compromises in technical performance. Despite their limitations, these instruments are remarkably useful for their intended application domain and should improve as computers continue to increase their performance.     

Imaging of mandible invasion by oral squamous cell carcinoma using computed tomography,cone-beam computed tomography and bone scintigraphy with SPECT

Objectives

The objective of this paper is to evaluate the predictability of preoperative tumour bone invasion of the mandible by squamous cell carcinoma of the oral cavity using CT, cone-beam CT and bone scintigraphy with SPECT.

Material and methods

Eighty-four patients who had received CT, SPECT or cone-beam computed tomography (CBCT), as well as a further 48 patients who undergone all these investigations for preoperative evaluation of bone invasion were included in the study. A case–control analysis and the receiver operating characteristics were performed. Histological results of bone specimens served as the gold standard for assessment of bone invasion.

Results

CBCT and SPECT showed a comparable sensitivity for bone invasion (93 % [CI 0.816–0.972] and 96 % [CI 0.867–0.990], respectively) which was significantly higher than that of CT (63 % [CI 0.488–0.752]). Further, CBCT obtained higher specificity than SPECT (62 % [CI 0.478–0.743] and 48 % [CI 0.342–0.614], respectively), whereas CT showed the best specificity among the investigation methods (81 % [CI 0.677–0.896]).

Conclusions

CT scan provides by its high specificity and positive predictive value a precise imaging technique for clinical routine. However, CBCT shows a much higher sensitivity for cortical bone invasion and a better negative predictive value. With a significantly lower exposure dose it can rule out this invasion effectively and prevent overtreatment.

Clinical relevance

Considering the high-resolution images delivered by CBCT along with minimized artefacts in the mandible it provides an alternative imaging technique, which could be combined and accomplished with another soft-tissue imaging modality like MRI to obtain optimal hard and soft-tissue visualisation in patients with squamous cell carcinoma of the oral cavity.     

Use of dental panoramic tomographs to predict the relation between mandibular third molar teeth and the inferior alveolar nerve. Radiological and surgical findings, and clinical outcome

OBJECTIVES: To compare preoperative radiological observations from dental panoramic tomographs (DPT), with surgical findings at removal of third molars with respect to the inferior alveolar nerve. STUDY DESIGN: One surgeon viewed the radiographs of 219 patients and recorded the radiological observations of the mandibular third molar tooth and the inferior alveolar nerve. The same surgeon removed the teeth and made detailed records of morphology of the root and its relation to the inferior alveolar nerve. Patients were reviewed postoperatively. RESULTS: A total of 300 teeth were removed and the neurovascular bundle was directly observed the root was grooved, or roots apices were deflected by the bundle in 35 (12%) cases. Postoperatively no patient had altered labial sensation. CONCLUSION: There was an intimate relation between the mandibular third molar tooth and the inferior alveolar nerve in 12 (51%) cases when darkening of the root was observed, and in only 11 (11%) cases when interruption of the radiopaque outline of the inferior alveolar neurovascular bundle was observed.