Visualisation of the mandibular canal by different radiographic techniques

6 mandibles were radiographically examined bilaterally to visualise the mandibular canal. 5 imaging techniques were used: periapical radiography, panoramic radiography, hypocycloidal tomography, spiral tomography and computed tomography (CT). Panoramic radiographs were obtained with 2 different X-ray machines. The CT-examinations comprised direct images and standard reconstructions based on axial slices. The specimens were subsequently sectioned for contact radiography. The visibility of the mandibular canal was estimated by 3 observers at special reference points on all radiographs and classified as clearly visible, questionable visibility or not visible. The contact radiographs served as the "gold standard". The inter-observer and the intra-observer agreement were assessed by calculating the overall agreement and the x value. Direct coronal computed tomography, as well as spiral and hypocycloidal tomography, gave better visualisation of the mandibular canal than periapical and panoramic radiography.     

Condylar shape analysis using panoramic radiography units and conventional tomography

OBJECTIVE: The objective of this study was to compare condyle shape between lateral temporomandibular joint (TMJ) images from axially corrected tomography and 3 panoramic radiography units with TMJ-specific programs. STUDY DESIGN: The TMJ from a single dry human skull was imaged with multidirectional tomography and the following 3 panoramic radiography units: Instrumentarium OP 100, Planmeca PM 2002 CC Proline, and Soredex Orthophos DS. A curve-fitting procedure (spline curves) was used to mathematically describe condyle outlines. One sample t tests were used to compare panoramic images against the tomograms (gold standard). RESULTS: A significant difference (P < .05) in condyle shape was found between TMJ tomography images and each of the 3 panoramic images. Images from the PM 2002 CC Proline demonstrated the smallest shape difference (13.4%), followed by the OP 100 (17.5%) and the Orthophos DS (24.8%). CONCLUSION: If panoramic radiography is to be used for the initial radiographic examination of the TMJ, practitioners should be aware of the potential for shape distortion of the condyle.     

Location of the mandibular canal: comparison of macroscopic findings, conventional radiography, and computed tomography

Four mandibular specimens were radiographically examined bilaterally to locate the mandibular canal. The following radiographic techniques were used: periapical and panoramic radiography, hypocycloidal tomography, and computed tomography (CT). The distance from the crest of the alveolar process to the superior border of the mandibular canal was measured in millimeters on all radiographs. The specimens were then sectioned, and the location of the mandibular canal (as measured on contact radiographs of the sections) was compared with measurements made on the other radiographs. The results showed that CT gave the most accurate position of the mandibular canal and is therefore probably the best method for preoperative planning of the implant surgery involving the area close to the mandibular canal.     

The subjective image quality of conventional and digital panoramic radiography among 6 to 10 year old children

OBJECTIVES: To compare the diagnostic quality of orthopantomographs made with the conventional unit Orthophos Siemens and the direct digital unit Planmeca 2000 cc Proline among children 6-10 years old and to investigate possible diferences on image interpretation between oral radiologists and pediatric dentists. METHODS: Study material included two independent groups of panoramic images (50 in each group) made with different panoramic modalities (digital conventional). Eight observers (four pediatric dentists and four oral radiologists) evaluated all images for diagnostic quality in 12 pre-determined areas using a 4-point rating scale. RESULTS: Digital and conventional panoramic radiography performed almost similarly as far as it concerns the specific diagnostic tasks rated with the exception of the interproximal contacts of mandibular molars where digital panoramic radiography was scored significantly higher and the periapical region of anterior mandible and anterior mandibular tooth germs where conventional panoramic radiography was found to be significantly better. Both oral radiologists and pediatric dentists graded similarly digital and conventional radiographs for a variety of diagnostic tasks. CONCLUSIONS: It can be concluded that diagnostic image quality obtained with the digital orthopantomograph unit Planmeca 2000 cc Proline was generally equal to image quality obtained with the conventional orthopantomograph unit Orthophos Plus CD. Image interpretation between oral radiologists and pediatric dentists was not substantially different     

Diagnostic ability of computed tomography using DentaScan software in endodontics: case reports

Radiographic examination is essential in diagnosis and treatment planning in endodontics. Conventional radiographs depict structures in two dimensions only. The ability to assess the area of interest in three dimensions is advantageous. Computed tomography is an imaging technique which produces three-dimensional images of an object by taking a series of two-dimensional sectional X-ray images. DentaScan is a computed tomography software program that allows the mandible and maxilla to be imaged in three planes: axial, panoramic, and cross-sectional. As computed tomography is used in endodontics, DentaScan can play a wider role in endodontic diagnosis. It provides valuable information in the assessment of the morphology of the root canal, diagnosis of root fractures, internal and external resorptions, pre-operative assessment of anatomic structures etc. The aim of this article is to explore the clinical usefulness of computed tomography and DentaScan in endodontic diagnosis, through a series of four cases of different endodontic problems.     

The evaluation of vertical heights of maxillary and mandibular bones and the location of anatomic landmarks in panoramic radiographs of edentulous patients for implant dentistry

The purpose of this study was to determine variations in the vertical height measurements in the edentulous maxilla and mandible, and to assess positions of the maxillary sinus, mandibular foramen, and the mandibular canal, which are important for implant length selection and planning using panoramic radiographs. The study sample included 346 edentulous alveolar ridges of 90 men and 83 women. Sixty-three dentate patients' panoramic radiographs were used for location of the first premolar and molar area. Panoramic radiographs were made with a Siemens Orthophos panoramic machine which had been standardized previously. All radiographs were made using a standardized manner by the same technician. Fourteen sites were measured on every panoramic radiograph whenever possible, eight sites in the maxilla and six sites in the mandible. Correlation analyses were performed between age groups and all measurements to determine if age is significant as a covariate. In order to examine the effect of gender the statistical analysis of differences between men and women was performed with Student t-test. The 5% significance level was used for statistical significancy. The height of the maxilla and the mandible in the anterior, first premolar, and first molar regions were significantly greater in men than in women. A majority of the most inferior border of the maxillary sinuses was located anterior to the first molar area (premolar regions) both in men (48.9%) and women (55.4%). Although, there was no statistically significant difference between edentulous men and women for the vertical distances from the mental foramen to the alveolar crest, and horizontal distances from mental foramen to midline, there were statistically significant differences between edentulous men and edentulous women for the vertical distances from the upper border of the mandibular canal to the alveolar crest in the first molar area. Mental foramens were located at the crest of the ridge in 7.2% of the edentulous women, and 6.7% of the edentulous men. The results of this study may guide clinicians to make primer decision of implant insertion area for implant supported prosthesis in edentulous patients.     

Evaluation of the inferior alveolar canal by cross-sectional hypocycloidal tomography

The aim of this study was to evaluate the possibility of locating the inferior alveolar canal (IAC) before mandibular posterior osteotomy or implant surgery using a computer-controlled hypocycloidal tomographic system. A 1-mm-thick cross section and a 6-mm-thick sagittal tomographic layer were made either through the proposed implant sites or through the center of the mandibular posterior teeth in 55 patients. The system used was a CommCAT IS 2000 tomographic unit in a hypocycloidal motion. The visibility of the location of the IAC was graded as excellent, good, fair, or invisible. In total, 119 sites were assessed. The visibility of the IAC was graded as excellent or good in 74% and fair in 11.7% of the sites. In 14.3% of cases, the canal was graded as invisible. Conventional hypocycloidal tomography has been shown to be a useful radiographic technique for preoperative assessment of the IAC in the posterior mandible.     

The use of 3 different imaging methods for the localization of the mandibular canal in dental implant planning

PURPOSE: The purpose of this study was to investigate the efficiency of panoramic radiography, conventional (cross-sectional) tomography, and computerized tomography for location of the mandibular canal before implant placement in the posterior region of the mandible. MATERIALS AND METHODS: Edentulous mandibles from 6 dry adult human skulls were used in this study. Four measurements (D1, D2, D3, D4) were made of 12 areas, one on each side of each mandible. Panoramic radiographs, conventional tomograms, and computerized tomograms were obtained. On each image, measurements were made for localization of the mandibular canal by one researcher. All measurements were repeated 3 times within a period of 3 weeks. Upon completion of imaging, the mandibles were surgically sectioned to provide direct measurements. The measurements obtained from the images were compared with direct measurements. Pearson correlation coefficients were calculated to detect statistical correlations between repeated measurements. The Dunnett t test was performed for statistical comparison of measurements from images and direct measurements. RESULTS: Pearson correlation coefficients showed strong linear correlation for all measurements (P < .01). No statistically significant difference was observed between direct measurement and D1, D2, or D4 (P < .05), but a statistically significant difference for D3 (buccolingual width 5 mm under mandibular crest; Dunnett t test; P > .05) between measurements was obtained from the images and direct measurements. CONCLUSION: The measurements obtained from computerized tomographic images were more consistent with direct measurements than the measurements obtained from panoramic radiographic images or conventional tomographic images.     

牙颌面锥形束CT与曲面体层X线检查对颌骨牙骨质瘤样病变诊断价值的比较研究

目的:比较牙颌面专用CBCT与曲面体层对颌骨牙骨质瘤的诊断价值。方法:对3例发生于上下颌骨中的牙骨质瘤患者,分别选用曲面体层和CBCT检查,并将检查结果进行比较分析,判断相互之间的一致性和差异性。结果:3例上下颌骨内牙骨质瘤病变,在曲面体层上均有显示,但CBCT检查可以在矢状位、冠状位和横断面上以多个层面准确地反映病变的位置及骨质破坏的情况。结论:CBCT在对上下颌骨牙骨质瘤的诊断较曲面体层更为有价值。     

An in vivo comparison of diagnostic information obtained from tuned-aperture computed tomography and conventional dental radiographic imaging modalities.

OBJECTIVE: The purpose of this study was to compare diagnostic information obtained by means of 3-dimensional tuned-aperture computed tomography (TACT) and by means of conventional radiography of patients requiring surgery. STUDY DESIGN: TACT produced digital images that yielded a series of tomographic slices viewed interactively. Controls were conventional periapical and/or panoramic radiographs. Each of 4 independent dentists performed 2 tasks, one requiring an estimation of confidence in their clinical assessments of the patient and the other requiring an estimation of the resulting diagnostic potential for altering associated treatment options. Data were analyzed through use of the nonparametric Mann-Whitney U Wilcoxon rank sum W test. RESULTS: A statistically significant difference for both tasks was observed (2-sided; P<.001). CONCLUSIONS: TACT displays were more diagnostically informative and had more impact on potential treatment options than did conventional radiographs.     

Comparison of three radiographic methods used to locate the mandibular canal in the buccolingual direction before bilateral sagittal split osteotomy

OBJECTIVE: Panoramic radiographs, computerized tomography (CT), and conventional spiral tomographic (Scanora, Soredex, Helsinki, Finland) radiographs were compared for their ability to locate the mandibular canal in the buccolingual direction. Furthermore, the relationship between the cortication of the mandibular canal in panoramic radiographs and the location of the canal in both computerized and conventional tomographic radiographs was assessed. STUDY DESIGN: The buccolingual location of the mandibular canal was determined bilaterally in twenty consecutive patients scheduled for bilateral sagittal split osteotomy. The position of the mandibular canal was evaluated by means of panoramic radiography, Scanora, and CT. The three imaging methods were compared for their ability to locate the mandibular canal in the buccolingual direction. The subjective neurosensory deficit of the lower lip and chin on both sides was registered preoperatively and at 4 days, 3 weeks, and 3 months after surgery, and the operative outcome was analyzed in relation to the distance from the mandibular canal to the buccal cortex of the mandible. RESULTS: CT gave better visualization of the mandibular canal than Scanora imaging. Cortication of the mandibular canal on the panoramic radiograph did not serve as a predictor of the proximity of the mandibular canal to the cortices of the mandible. At 3-month follow-up, there were only eight operated sides with abnormal sensation of the lower lip and chin. In seven of these sides, the distance from the mandibular canal to the buccal cortex was less than 2 mm. CONCLUSION: The buccolingual location of the mandibular canal is visualized better with CT than with Scanora or panoramic radiographs.     

Third molar position: reliability of panoramic radiography.

PURPOSE: The purpose of the present study was to determine whether panoramic radiographs could predict physical contact between the mandibular third molar and the mandibular canal on limited cone-beam computed tomography, known as dental 3D-CT (3-dimensional computed tomography [3D-CT]). PATIENTS AND METHODS: The association of images between the panoramic radiograph and the dental 3D-CT was investigated in a cross-sectional study. Seventy-three lower third molars in 65 patients were examined. Findings of absence or presence of the white line of the mandibular canal wall on panoramic radiographs and contact or separation between the tooth and the mandibular canal on dental 3D-CT were compared. RESULTS: Absence of a superior white line on panoramic radiography was associated with an increased risk of contact between the third molar and the mandibular canal on dental 3D-CT, even when the effects of tooth position, age, and gender were taken into account. The multivariate adjusted odds ratio was 10.79. Women were more likely to have contact between the 2 structures on dental 3D-CT when their panoramic radiograph showed absence of the white line. CONCLUSIONS: Panoramic radiography is useful for predicting to a limited extent physical contact between the mandibular third molar and the mandibular canal on dental 3D-CT.     

Accuracy of digital panoramic images displayed on monitor, glossy paper, and film for assessment of mandibular third molars

OBJECTIVE: The aim of this study was to compare the accuracy of 3 modalities of digital panoramic radiographs-monitor-displayed images and printed copies on glossy paper and on blue transparent film-for assessment of position and morphology of mandibular third molars. STUDY DESIGN: 164 third molars were recorded with one of 2 digital panoramic systems (Digora and Orthophos Plus) and assessed by 4 observers on 3 radiographic modalities: monitor display, glossy paper, and transparent film. The assessments were compared with surgeons' findings at the time of the operation ("gold standard"). RESULTS: Overall, the observer variation was larger than the variation between methods. A detailed paired analysis revealed some differences between the modalities for some diagnostic categories, but these were few and inconsistent. CONCLUSION: Printed images from the Kodak 1200 ink-jet printer on glossy paper and blue transparent film may be as accurate as the original monitor-displayed digital panoramic images from the Digora and Orthophos Plus systems for assessment of position and morphology of mandibular third molars.     

Demonstration of the accessory mental foramen using rotational panoramic radiography compared with cone-beam computed tomography

Objective: Rotational panoramic radiography is routinely used in dental practice. It has not been clarified, however, whether an accessory mental foramen can be demonstrated using this technique. The visibility of accessory mental foramina on rotational panoramic radiographs was compared with those on para‐panoramic images reconstructed from cone‐beam computed tomographic (CBCT) images. Materials and methods: A total of 365 patients (130 males and 235 females) were retrospectively analyzed. Para‐panoramic images were reconstructed from CBCT images with the accessory mental foramen/foramina using three‐dimensional visualization and measurement software, and then the accessory mental foramen on rotational panoramic images was compared with that on para‐panoramic images. Results: A total of 37 accessory mental foramina were observed in 28 patients on CBCT images. The rate of being able to visualize the accessory mental foramen or bony canal between the point of bifurcation from the mandibular canal and the accessory mental foramen on rotational panoramic radiographs was 48.6% (18 of 37 accessory mental foramina). Conclusion: Approximately half of the accessory mental foramina‐positive CBCT images demonstrated the accessory mental foramen, or bony canal between the point of bifurcation from the mandibular canal and accessory mental foramen on rotational panoramic radiographs. To cite this article:
Naitoh M, Yoshida K, Nakahara K, Gotoh K, Ariji E. Demonstration of accessory mental foramen using rotational panoramic radiography compared with cone‐beam computed tomography.
Clin. Oral Impl. Res. xx , 2011; 000–000.     

A study on reliability of the tomographic image of the temporomandibular joint

Summary For this study, seven different types of phantom were made simulating the condyle. The phantoms attached to a human dry skull were tomographed using the Polytome-U, under identical conditions to those of tomography for patients. There was no significant difference of the images between tube side and film side of the mandible. The images of the medial part of the TMJ were clearer than that of the lateral part. A discrepancy of contours on the focal plane between the phantom and the tomographic image occurred when the inclination of the phantom surface was larger than the maximum exposure angle. Concerning the influence of focal movements to image quality, the images obtained from hypocycloidal movements were superior with minimum superimposition, although the contrast of the image varied when the phase of the hypocycloidal movements were altered. Any sectional images were not manifested with the phantoms when the inclination of the phantom surface was larger than 23 degrees. Furthermore, 106 condyles from human dry skull were examined on the area of which the inclination of the condylar surface was less than 23 degrees. The mean latero-medial distance of the area was 14.1mm, which corresponded to 75% of whole latero-medial distance of the condyle.     

Contrast perception in digitized panoramic radiographs compared with their film-based origin

OBJECTIVES: We sought to compare the visual image quality of film-based and digitized panoramic radiographs through use of a hole-containing test wedge. STUDY DESIGN: An aluminum wedge containing 100 cells, of which 90 were given shallow holes, was exposed in the film-based Orthophos CD panoramic unit. Two radiographs subjectively exhibiting optimum contrast were selected. Films were digitized with a charge-coupled device flatbed scanner at 300 dpi. Films and digitized images were rated cellwise by 2 similar groups of 50 observers each with respect to spot perception. RESULTS: The mean sensitivity was 0.26 +/- 0.09 for film and 0.20 +/- 0.07 for digitized images (P =.000), with a pronounced decline in the latter in regions of high background density. The average specificity was 0.93 +/- 0.07 for film versus 0.92 +/- 0.08 for digitized images (P = 0.213). CONCLUSION: Film yielded a significantly higher sensitivity, but this absolute difference was actually small compared with that of the digitized images.     

Research methods in dentistry 9. Follow-up of permucosal implants in an edentate mandible using panoramic radiography

Panoramic radiographs are frequently used for routine follow-up of mandibular implants. The objective of this study was to determine whether measurement on a panoramic radiograph of the vertical dimension of the mandible near by an implant, using the known implant length as a reference, is a reliable method. In 11 patients, 2 permucosal implants were placed in the anterior part of the edentulous mandible. During the first year after implantation, 2 panoramic radiographs and 2 sets of standardized oblique lateral cephalometric radiographs were made. Oblique lateral cephalometric radiographs are the golden standard for measuring the vertical dimension of an edentulous mandible. The length of the implants and the vertical dimension of the mandible dorsally to the implants were measured on all oblique lateral cephalometric radiographs. The measured and known implant length were used to calculate the image enlargement factor. This factor was used to calculate the real vertical dimension of the mandible. The same measurement procedures were performed on the panoramic radiographs. Using a paired t-test, the calculated values of the vertical dimensions of the mandibles found on panoramic radiographs were compared with the calculated values found on oblique lateral cephalometric radiographs. No statistically significant differences were found. It was concluded that under the described circumstances, panoramic radiographs can be used for reliable measurement of the vertical dimension of the mandible near by permucosal implants.     

Accuracy of linear measurements before and after digitizing periapical and panoramic radiography images

The aim of this study was to evaluate the accuracy of linear measurements made on conventional and digitized periapical and panoramic radiographic images of dry human hemi-mandibles. Images from the posterior region of 22 dry human hemi-mandibles were obtained by conventional panoramic and periapical radiography technique. Using a digital caliper, 3 vertical measurements were marked directly on the dry hemi-mandibles (reference measurements) as well as on the tracing from the conventional radiographic images of the specimens made onto acetate paper sheet: Distance 1: between the upper limit of the alveolar ridge and the lower limit at the mandible base; Distance 2: between the upper limit of the alveolar ridge and the upper limit of the mandibular canal; Distance 3: between the lower limit of the mandibular canal and the lower limit of the mandible base. Next, the radiographs were digitized and the three measurements were made on the digital images using UTHSCSA Image Tool software. Data were analyzed statistically by one-way ANOVA (α=0.05). There was no statistically significant differences (p>0.05) between periapical and panoramic radiographs or between the measurements recorded using the digital caliper and UTHSCSA software compared with dry mandible specimens for Distances 1 (p=0.783), 2 (p=0.986) and 3 (p=0.129). In conclusion, the radiographic techniques evaluated in this study are reliable for vertical bone measurements on selected areas and the UTHSCA Image Tool software is an appropriate measurement method.     

Measurements of distances related to the mandibular canal in radiographs

Before implant surgery in the mandibular side segment, it is of utmost interest to locate the mandibular canal in radiographs to avoid interference with the neurovascular bundle during surgery. Six mandibular specimens were radiographically examined with 2 panoramic and 3 tomographic techniques. The distances between the superior border of the canal and the alveolar crest and between the mandibular base and the inferior border of the canal were measured. In addition, the height of the canal was measured. The measurements were performed by 3 or 4 observers and compared with measurements on contact radiographs of the same areas. Tomography gave more accurate values of the above distances than panoramic techniaues. The variation between observers in detecting the mandibular canal Aas large.