Limited cone-beam CT and intraoral radiography for the diagnosis of periapical pathology

Effectiveness of limited cone-beam computed tomography in the detection of horizontal root fracture

To compare the diagnostic accuracy of conventional film radiography, charge coupled device (CCD) and photostimulable phosphor plate (PSP) digital images and limited cone-beam computed tomography in detecting simulated horizontal root fracture. Root fractures were created in the horizontal plane in 18 teeth by a mechanical force and fragments were relocated. Another 18 intact teeth with no horizontal root fracture served as a control group. Thirty-six teeth were placed in the respective empty maxillary anterior sockets of a human dry skull in groups three by three. Intraoral radiographs were obtained in three different vertical views by utilizing Eastman Kodak E-speed film, CCD sensor, RVG 5.0 Trophy and a PSP sensor Digora, Optime. Cone beam CT images were taken with a unit (3D Accuitomo; J Morita MFG. Corp, Kyoto, Japan). Three dental radiologists separately examined the intraoral film, PSP, CCD and cone beam CT images for the presence of horizontal root fracture. Specificity and sensitivity for each radiographic technique were calculated. Kappa statistics was used for assessing the agreement between observers. Chi-square statistics was used to determine whether there were differences between the systems. Results were considered significant at P < 0.05. Cone beam CT images revealed significantly higher sensitivities (P < 0.05) than the intraoral systems between which no significant differences were found. Specificities did not show any statistically significant differences between any of the four systems. The kappa values for inter-observer agreement between observers (four pairs) ranged between 0.82-0.90 for the 3DX evaluations and between 0.63-0.71 for the different types of intraoral images. Limited cone beam CT, outperformed the two-dimensional intraoral, conventional as well as digital, radiographic methods in detecting simulated horizontal root fracture.

Void detection in root fillings using intraoral analogue, intraoral digital and cone beam CT images

AIM

To compare void detection in root fillings using different radiographic imaging techniques: intraoral analogue, intraoral digital and cone beam CT (CBCT) images and to assess factors influencing small void detection.

METHODOLOGY

Two straight root canals in canine teeth were prepared. Calibrated steel wires of five different diameters (200, 300, 350, 500, 800 microm) were inserted respectively in the canal after the injection of a sealer. To simulate filling voids of known dimensions, the wires were removed after the sealer had set. Each sample was imaged, using a Minray X-ray tube (Soredex, Helsinki, Finland) at optimal clinical settings combined with Vistascan PSP (Dürr Dental, Bietigheim-Bissingen, Germany), Digora Optime PSP (Soredex), Sigma CCD (Instrumentarium, Tuusula, Finland) and E-speed films (Agfa-Gevaert, Mortsel, Belgium). The teeth were also imaged using CBCT (3D Accuitomo, Morita, Japan). A generalized mixed model and ANOVA analysis were used on the acquired data (Tukey-Kramer correction).

RESULTS

There was no evidence that the factor 'root level' affected void detection in root fillings. 'Void size' was a main determining factor as all voids larger than 300 microm were determined with all techniques. For the smaller voids, there were significant differences between the 5 imaging techniques at different void sizes and different root levels.

CONCLUSIONS

Void size and imaging technique were main determining factors. Voids larger than 300 mum were determined with all imaging techniques. For small void detection, all digital intraoral techniques performed better than intraoral analogue and CBCT images.

[A new modality for dentomaxillofacial imaging: cone beam CT]

Cone beam CT is an imaging technique used worldwide. It is a reliable and credible alternative to CT scan for dentomaxillofacial imaging. Radiation exposure may vary from one machine to another, but it remains definitely lower than CT dose levels. This technique is compatible with dental implant software. The major diagnostic advantage is the exquisite spatial resolution. The main pitfall is the poor contrast of face and neck soft tissues, due to a lower density resolution compared to CT scan.

Clinical use of navigation based on cone-beam computer tomography in maxillofacial surgery

Image-guidance in maxillofacial surgery is based predominantly on computed tomographic (CT) images. Its main disadvantage is the considerable amount of radiation to which the patient is exposed, and dental metal artefacts. Recently, a new class of devices based on the concept of cone-beam computed tomography (CBCT) has been introduced for maxillofacial imaging, which we have investigated. In a clinical study, the first seven patients to be operated using a navigation system based on CBCT images, were evaluated. In all cases patient to image recording was uneventful and the surgical objective was reached. The guidance given by the navigation system was helpful. CBCT is an alternative to conventional CT, gives a lower dose of radiation, and costs less. Limitations in the quality of the images and the size of the field of view may restrict its use. It is suitable for image-guided surgery using a navigation system as long as the images show enough of the relevant anatomy and pathology.

Conebeam CT of the head and neck, part 2: clinical applications

SUMMARY

Conebeam x-ray CT (CBCT) is being increasingly used for point-of-service head and neck and dentomaxillofacial imaging. This technique provides relatively high isotropic spatial resolution of osseous structures with a reduced radiation dose compared with conventional CT scans. In this second installment in a 2-part review, the clinical applications in the dentomaxillofacial and head and neck regions will be explored, with particular emphasis on diagnostic imaging of the sinuses, temporal bone, and craniofacial structures. Several controversies surrounding the emergence of CBCT technology will also be addressed.

Use of cone-beam volumetric tomography in the diagnosis of root fractures

OBJECTIVES

The diagnosis of root fractures by conventional radiographs is still difficult because of limitations of 2D images. Cone-beam volumetric tomography improves the diagnosis capacity in dentistry, such as increased radiation dose to the patient and presence of artifacts on the image.

STUDY DESIGN

This study compared the images obtained on conventional periapical radiographs and 3D scans (Accuitomo 3DX) for the diagnosis of root fractures. Twenty patients with suspected root fractures were submitted to examination by periapical radiography and CBCT. Two professionals, unaware of the symptomatology, examined these radiographs and CBCT images according to pre-established scores, which were later checked against the signs and symptoms.

RESULTS

The results revealed statistical difference for cone-beam volumetric tomography compared with conventional radiographs in the diagnosis of root fractures.

CONCLUSION

It could be concluded that cone-beam volumetric tomography was better than conventional radiography in the diagnosis of root fractures, thereby constituting an excellent alternative for diagnosis in general practice.

Management of ectopic maxillary canines: variations among orthodontists

OBJECTIVE

To document and analyze factors involved in decision-making by orthodontists in managing disturbances of eruption of maxillary canines.

MATERIAL AND METHODS

The participants comprised orthodontic specialists and active members of the Swedish Orthodontic Society. Those selected for the study sample were under 65 years of age or younger and had been treating orthodontic patients for at least 1 year as a specialist. Three typical cases were presented for treatment proposals. The case notes, including radiographs and specific background data, were sent to the 182 selected orthodontists. The orthodontists were also requested to complete a questionnaire about practice profile, comprising eight questions.

RESULTS

The response rate was 86.3%; yielding 157 participants (mean age 53.8 years, SD 8.12). Analysis disclosed no differences between responders and nonresponders regarding age, gender, and years of specialist practice. For treatment plans based on panoramic radiographs, intraoral radiographs, and status and anamnesis, there was general consensus. However, when supplementary information from computer tomography (CT) was provided, disclosing root resorption half-way to the pulp or more on the lateral incisor, the orthodontists' treatment proposals varied. Gender, age, and practice profile of the orthodontists had little association with the decision-making.

CONCLUSIONS

Supplementary CT information led to variations in decision-making with respect to treatment of eruption disturbances of maxillary canines. This lack of consensus among specialist orthodontists can have negative implications for patients.

Cone-beam imaging in dentistry

Cone-beam imaging has gained broad acceptance in dentistry in the last 5 years. The purpose of this review is to describe the use in dentistry and consider issues requiring further development. Cone-beam machines emit an x-ray beam shaped liked a cone rather than a fan as in conventional computed tomography (CT) machines. After this beam passes through the patient the remnant beam is captured on an amorphous silicon flat panel or image intensifier/charge-coupled device (CCD) detector. The beam diameter ranges from 4 to 30 cm and exposes the head in one pass around the patient capturing from 160 to 599 basis images. These images are used to compute a volume from which planar or curved reconstructions can be extracted in any orientation. Voxels are isotropic and can be as small as 0.125 mm. 3-D images of bone or soft tissue surfaces can also be generated. In dentistry the most common indications for cone-beam imaging are assessment of the jaws for placement of dental implants, evaluation of the temporomandibular joints for osseous degenerative changes, examination of teeth and facial structures for orthodontic treatment planning, evaluation of the proximity of lower wisdom teeth to the mandibular nerve prior to extraction, and evaluation of teeth and bone for signs of infections, cysts, or tumors. Cone-beam images have largely replaced conventional tomography for these tasks. The effective dose from cone-beam imaging ranges from 6 to 477 microSv. The cost of the equipment is relatively low, about $150,000 to $300,000. Issues to be considered are the training of individuals making and interpreting cone-beam images, as well as means to further reduce patient exposure.

The evolution and application of dental maxillofacial imaging modalities

During the last decades, an exciting new array of imaging modalities, such as digital imaging, CT, MRI, positron emission tomography, and cone-beam CT (CBCT), has provided astounding new images that continually contribute to the accuracy of diagnostic tasks of the maxillofacial region. The most recent, cone-beam imaging, is gaining rapid acceptance in dentistry because it provides cross-sectional imaging that is often a valuable supplement to intraoral and panoramic radiographs. The information content in such examinations is high and the dose and costs are low. The increasing trend toward the use of CBCT in dental offices may be expected to result in improved diagnosis, but with increased patient dose and health care costs. Using CBCT as a secondary imaging tool helps optimize health-to-risk ratio.

A new periapical index based on cone beam computed tomography

The purpose of this study was to evaluate a new periapical index based on cone beam computed tomography (CBCT) for identification of apical periodontitis (AP). The periapical index proposed in this study (CBCTPAI) was developed on the basis of criteria established from measurements corresponding to periapical radiolucency interpreted on CBCT scans. Radiolucent images suggestive of periapical lesions were measured by using the working tools of Planimp software on CBCT scans in 3 dimensions: buccopalatal, mesiodistal, and diagonal. The CBCTPAI was determined by the largest lesion extension. A 6-point (0-5) scoring system was used with 2 additional variables, expansion of cortical bone and destruction of cortical bone. A total of 1014 images (periapical radiographs and CBCT scans) originally taken from 596 patients were evaluated by 3 observers by using the CBCTPAI criteria. AP was identified in 39.5% and 60.9% of cases by radiography and CBCT, respectively (P < .01). The CBCTPAI offers an accurate diagnostic method for use with high-resolution images, which can reduce the incidence of false-negative diagnosis, minimize observer interference, and increase the reliability of epidemiologic studies, especially those referring to AP prevalence and severity.

Detection of periapical lesion development by conventional radiography or computed tomography

OBJECTIVE

The aim of this study was to detect the development of experimentally induced periapical lesions using conventional radiography and computed tomography.

STUDY DESIGN

The root canals of dogs' teeth were exposed to the oral environment for 7 days for contamination and then sealed for 7 days (GI), 15 days (GII), 30 days (GIII), and 60 days (GIV). Immediately after each experimental period, radiographs and tomograms were taken in order to detect the occurrence of periapical bone resorption. The periapical radiographs were digitized and areas of bone resorption were measured using the VIXWIN 2000 software. Scores were assigned to the tomograms based on the progression of periapical bone resorption. The specimens were evaluated by calibrated examiners who were blinded to the groups. The radiographic results were analyzed by ANOVA and Tukey's test (P < .05) and the tomographic results were analyzed by Kruskal-Wallis and Dunn's tests (P < .05).

RESULTS

The radiographic evaluation did not reveal periapical lesions at the 7-day control. Lesions were radiographically visible at 15 and 30 days (47.4% and 77.8% of the cases, respectively) and presented similar dimensions (P > .05). At 60 days, lesions were detected in all specimens, presenting larger dimensions than those of the earlier evaluation periods (P < .05). The tomographic evaluation detected lesions at 7 and 15 days (32.5% and 83.3% of the cases, respectively). Lesions were detected in all specimens at the 30- and 60-day periods, when the greatest values of bone resorption were observed (P < .05).

CONCLUSIONS

Tomography was able to detect periapical lesion development in its initial stages, even when the lesions were undetectable radiographically.

Diagnostic accuracy of cone-beam CT in the assessment of mandibular invasion of lower gingival carcinoma: comparison with conventional panoramic radiography

PURPOSE

To evaluate the diagnostic accuracy of cone-beam CT in assessing mandibular invasion by lower gingival carcinoma and compare it with that of panoramic radiography.

PATIENTS AND METHODS

Fifty patients with squamous cell carcinoma of the lower gingiva who were examined by both panoramic radiography and cone-beam CT before surgery were included in this study. Five radiologists used a 6-point rating scale to independently evaluate cone-beam CT and panoramic images for the presence or absence of alveolar bone and mandibular canal involvement by tumor. Using the histopathogical findings as the gold standard, we calculated and compared the area under the receiver operating characteristic curve (Az value) and the sensitivity and specificity of the two imaging modalities.

RESULTS

In evaluations of both alveolar bone and mandibular canal involvement, the mean Az value for cone-beam CT (0.918 and 0.977, respectively) was significantly higher than that for panoramic radiography (0.793 and 0.872, respectively). The mean sensitivity for cone-beam CT (89% and 99%, respectively) was significantly higher than that for panoramic radiography (73% and 56%, respectively). There was no significant difference in the mean specificity. While cone-beam CT could provide high-resolution three-dimensional images, the image quality around the alveolar crest was often hampered by severe dental artifacts and image noise, resulting in difficulties in detecting subtle alveolar invasion.

CONCLUSION

Cone-beam CT was significantly superior to panoramic radiography in evaluating mandibular invasion by lower gingival carcinoma. Its diagnostic value in detecting subtle alveolar invasion, however, may be limited by severe dental artifacts and image noise.

Effective dosages for recording Veraviewepocs dental panoramic images: analog film, digital, and panoramic scout for CBCT

OBJECTIVE

The aim of this study was to evaluate the effective doses from analog film, panoramic digital, and panoramic scout for cone-beam computerized tomography (CT).

STUDY DESIGN

Three different types of Veraviewepocs machines were investigated: Veraviewepocs Conventional, Veraviewepocs Digital, and Veraviewepocs 3D (Morita, Kyoto, Japan). Organ absorbed doses were measured using an anthropomorphic phantom loaded with thermoluminescent dosimeters (TLD 100H) at 16 sites located in sensitive organs. The resulting effective organ doses (muSv) were compared by descriptive statistics.

RESULTS

The highest value (5.2 muSv) was for Veraviewepocs Conventional. The Veraviewepocs Digital (2.7 muSv) and Veraviewepocs 3D (2.95 muSv) presented low effective doses in the same range.

CONCLUSIONS

The panoramic digital system delivered the least radiation dose. The use of the panoramic scout for cone-beam CT was marginally higher in dose than its 2D counterpart.

Cone-beam computed tomography in assessment of periodontal ligament space: in vitro study on artificial tooth model

The aim of this in vitro study was to compare cone-beam computed tomography (CBCT) to conventional radiography (RG) in the assessment of the periodontal ligament space. A phantom with a variable "artificial" periodontal ligament space (0, 100, 200, 300, and 400 microm) was used as a model. The examinations were performed simultaneously with RG and NewTom 9000 digital volume tomograph. Assorted after increasing widths, 15 RGs and 15 CBCT images were presented for judgment to 20 dentists (DD), 20 dental assistants, and 20 dental students. Several weeks later, the same images were randomly mixed and presented to the same 20 DD again. The trial shows that RG gaps wider than 200 microm could be correctly identified by all participants with an accuracy of nearly 100%. A significant difference was observed between the modalities (p<0.05 and p<0.001) where conventional RGs performed better than CBCT for assessment of periodontal ligament space. Interobserver variation in relation to each technique was evaluated and no significant difference was found (p>0.05). In subjective evaluations of image quality with CBCT, the results were basically inferior for images of artificial periodontal ligament space, regardless of the experience of the observers.

Accuracy of cone beam computed tomography and panoramic and periapical radiography for detection of apical periodontitis

The aim of this study was to evaluate the accuracy of imaging methods for detection of apical periodontitis (AP). Imaging records from a consecutive sample of 888 imaging exams of patients with endodontic infection (1508 teeth), including cone beam computed tomography (CBCT) and panoramic and periapical radiographs, were selected. Sensitivity, specificity, predictive values, and accuracy of periapical and panoramic radiographs were calculated. Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic accuracy of the panoramic and periapical images. Prevalence of AP was significantly higher with CBCT. Overall sensitivity was 0.55 and 0.28 for periapical and panoramic radiographs, respectively. ROC curves and area under curve (AUC) with periapical radiography showed a high accuracy for the cutoff value of 5 for both periapical (AUC, 0.90) and panoramic (AUC, 0.84) radiographs. AP was correctly identified with conventional methods when showed advanced status. CBCT was proved to be accurate to identify AP.

The potential applications of cone beam computed tomography in the management of endodontic problems

AIM

To provide core information on cone beam computed tomography (CBCT) technology and its potential applications in endodontic practice.

SUMMARY

CBCT has been specifically designed to produce undistorted three-dimensional information of the maxillofacial skeleton as well as three-dimensional images of the teeth and their surrounding tissues. This is usually achieved with a substantially lower effective dose compared with conventional medical computed tomography (CT). Periapical disease may be detected sooner using CBCT compared with periapical views, and the true size, extent, nature and position of periapical and resorptive lesions can be assessed. Root fractures, root canal anatomy and the true nature of the alveolar bone topography around teeth may be assessed. CBCT scans are desirable to assess posterior teeth prior to periapical surgery, as the thickness of the cortical and cancellous bone can be accurately determined as can the inclination of roots in relation to the surrounding jaw. The relationship of anatomical structures such as the maxillary sinus and inferior dental nerve to the root apices may also be clearly visualized.

KEY LEARNING POINTS

CBCT has a low effective dose in the same order of magnitude as conventional dental radiographs. CBCT has numerous potential applications in the management of endodontic problems.

The use of cone beam computed tomography in the management of external cervical resorption lesions

AIM

To report the use of cone beam computed tomography in the assessment of external cervical resorption lesions.

SUMMARY

Asymptomatic external cervical resorption lesions were diagnosed radiographically in two patients. Clinical examination in both cases was unremarkable. Cone beam computed tomography scans revealed the true nature of the lesions in three dimensions. The resorption lesion in case 1 was confined predominantly to the buccal aspect of the root, the lesion had not perforated into the root canal. A mucoperiosteal flap was raised to gain access to the lesion, the resorptive lesion was excavated and the defect repaired with glass ionomer cement. In case 2 the cone beam computed tomography scan revealed that the resorptive lesion was more extensive than it appeared radiographically, making the prognosis of reparative treatment very poor. In this case, the patient was advised to have the tooth extracted.

KEY LEARNING POINTS

The true extent of external cervical resorption lesions cannot always be estimated from conventional radiographs. Cone beam computed tomography can be a useful diagnostic tool in the management of external cervical resorption lesions.

A comparative study of cone-beam computed tomography and conventional panoramic radiography in assessing the topographic relationship between the mandibular canal and impacted third molars

OBJECTIVE

To evaluate the diagnostic accuracy of cone-beam CT compared with panoramic images in predicting neurovascular bundle exposure during extraction of impacted mandibular third molars.

STUDY DESIGN

Cone-beam CT and panoramic images of 142 impacted mandibular third molars were prospectively evaluated to assess tooth relationship to the mandibular canal. These interpretations were then correlated with intraoperative findings. The sensitivity and specificity of the 2 modalities in predicting neurovascular bundle exposure at extraction were calculated and compared. The diagnostic criterion for panoramic images was defined using multivariate logistic regression analysis.

RESULTS

In predicting the exposure, the sensitivity and specificity were 93% and 77% for cone-beam CT, and 70% and 63% for panoramic images, respectively. Cone-beam CT was significantly superior to panoramic images in both sensitivity and specificity.

CONCLUSION

Cone-beam CT was significantly superior to panoramic images in predicting neurovascular bundle exposure during extraction of impacted mandibular third molar teeth.