Juxta-apical radiolucency: relation to the mandibular canal and cortical plates based on cone beam CT imaging

Proximity of mandibular third molar root(s) to surrounding cortical bone: cone beam computed tomography (CBCT) and panoramic findings

PURPOSE

We evaluated the relationship between mandibular third molar roots (M3Ms) and surrounding cortical bone using cone beam computed tomography (CBCT) and panoramic findings. We studied (a) the location of mandibular third molar roots in relation with cortical bone in terms of contact, penetration, and perforation on CBCT; (b) the relationship between characteristics of a root in panoramic findings and the CBCT image (entire and segmentally); and (c) the relationship of the root plane in panoramic findings vs. CBCT.

MATERIAL AND METHODS

One hundred five teeth with 224 roots of mandibular third molar from 73 patients were evaluated by using cone beam computed tomography and panoramic image.

RESULT

The relationships were assessed using 105 images of impacted M3Ms: 104/105 (99%) showed cortical bone involvement (30.4% penetration and 68.6% perforation). The more apical the segment, the higher the proportion of perforation. Most (79.9%) of the M3M roots involved a lingual cortex with 46.9% penetration and 49.2% perforation. The panoramic signs of segmental root images-viz. clear and blurred-were not associated with cortical penetration or perforation. Panoramic signs of individual root images-in the same and different planes-could be used to predict root plane M3M roots. The same appearance in the panoramic image was significantly related to the same plane of the root in CBCT (p-value 0.048).

CONCLUSION

These findings could contribute to enhanced radiological assessment and surgical planning.

Evaluating the presence of IAN injury in patients with juxta-apical radiolucency after third molar surgery: a retrospective cohort study

Background

Juxta-apical radiolucency (JAR) has been presented as a radiographic sign, suggestive of the IAN injury through third molar surgery. This study aimed to evaluate the relation of JAR with IAN injury in cone-beam computed tomography (CBCT) images and to determine whether the presence of JAR is related to tooth angulation, proximity to the mandibular canal, position to the IAN, and thinning of the cortical plates.

Methods

Of an initial sample of 545 mandibular third molars, a total of 75 JAR⁺ and 75 JAR⁻ teeth were evaluated by CBCT. We assessed the relationship between the presence of JAR in cone-beam computed tomography (CBCT) images and the presence of IAN injury after mandibular third molar surgeries. Moreover, we investigated whether the presence of IAN injury is related to tooth angulation, proximity to the mandibular canal, position to the IAN, and thinning of the cortical plates. Descriptive statistics, Chi-square test, and Fisher’s exact test were performed for statistical analysis.

Results

A significant relationship was found between JAR and temporary IAN injury (P = 0.036). However, there was no case of permanent IAN injury. IAN injury showed no significant relationship with the tooth angulation, position to IAN and proximity to the mandibular canal, lingual cortical plate thinning, sex, and age.

Conclusions

JAR is generally in contact with the mandibular canal, and some degree of cortical thinning can be found in most cases. In this study, JAR was significantly related to temporary IAN injury. JAR may increase the risk of nerve injury during the surgical removal of third molars.

Imaginological characterization of multiple myeloma lesions of the jaws through cone-beam computed tomography

PURPOSE

To establish an evaluation protocol for the identification and description of the variations in multiple myeloma (MM) lesions of the jaws, by means of cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Tomography exams from 33 MM patients were evaluated in this retrospective observational study. The reconstructions were analyzed simultaneously, according to the established protocol, with the following description criteria: anatomic location, size, margins, inner aspect, relationship with adjacent structures, and presence or absence of a punched-out aspect. The exams were further subdivided into groups of patients using, or not bisphosphonates.

RESULTS

There were osteolytic lesions in 100% of cases, most of which were extended to more than one anatomical region. Poorly defined margins were more frequent in the maxilla than in the mandible. Extensive bone resorption presenting multilocular areas was the most frequently observed aspect, being 86.2% for maxilla and 87.9% for mandible. In relation to bisphosphonates, patients who used the medication had more poorly defined bone margins and contortions (68.6%) than those who did not undergo drug therapy (31.4%). No well-defined lesions were observed (p = 0.34%).

CONCLUSION

It was possible to establish a protocol for evaluation of MM lesions in CBCT images and to identify that when evaluated three-dimensional, lesions tend to be poorly defined and have no pattern of description, as described in two-dimensional "punched-out".

Is juxta-apical radiolucency a reliable risk factor for injury to the inferior alveolar nerve during removal of lower third molars?

The aim of this study was to find out if juxta-apical radiolucency (JAR) is a reliable risk factor for injury to the inferior alveolar nerve (IAN) during removal of lower third molars. We designed a cohort study of patients whose dental panoramic tomograms (DPT) had shown JAR before complete removal of lower wisdom teeth. The outcome variable was postoperative permanent neurosensory disturbance of the IAN. A total of 39 patients (50 lower third molars) were identified and screened for permanent neurosensory disturbance. None reported any permanently altered sensation 18 months after the operation. Based on our group, the presence of JAR does not seem to be a reliable predictor of the risk of permanent injury to the IAN during removal of lower third molars.

Comparison of panoramic radiography and cone beam CT in the assessment of juxta-apical radiolucency

OBJECTIVES

To compare the performance of panoramic radiography (PAN) and cone beam CT (CBCT) in the detection of juxta-apical radiolucency (JAR), as well as to investigate, in CBCT images, if there are factors associated with the detection of JAR on PAN.

METHODS

Two oral radiologists assessed the presence of JAR in PAN and CBCT images of 175 individuals (308 mandibular third molars). The cortical plates involvement and the JAR size and location were assessed on CBCT to evaluate if these factors were related to JAR detection on PAN. McNemar's test and multiple logistic regression were performed.

RESULTS

PAN and CBCT differed significantly in the detection of JAR (p = 0.001). On PAN, JAR was identified on 24% of the patients while on CBCT its detection increased to 32.6%. JAR was detected only on CBCT and only on PAN in 26 and 7 cases, respectively. Distal/mesial surfaces of dental roots were where JAR was mostly located (84.5%), cortical thinning was found in 59.2% of cases and the mean (SD) of JAR size was 5.03 (±1.8) mm. However, these factors were not associated with JAR detection on PAN (p > 0.05). On the other hand, the location of the cortical involvement (if buccal or lingual) was associated with JAR detection on PAN, which was more detectable when the thinning was on buccal cortical.

CONCLUSIONS

Juxta-apical radiolucency is more often detected on CBCT than on PAN. JAR detection on PAN was improved when it was related to the buccal cortical plate of the mandible.

Mandibular canal visibility using a plain volumetric interpolated breath-hold examination sequence in MRI

OBJECTIVES

To evaluate the validity of plain volumetric interpolated breath-hold examinations (VIBEs) for detecting the course of the mandibular canal, and to compare the results with contrast-enhanced (CE) VIBE images.

METHODS

From our imaging archives, we collected 28 cases taken with a VIBE sequence both before and after intravenous administration of gadolinium hydrate, and then two observers evaluated neurovascular bundle (NVB) visibility in the VIBE images. For the invisible NVB cases, we identified the invisible areas and analysed the causes of invisibility. For cases that also had corresponding CT thin slice images, we obtained a fusion image between MRI and CT, and investigated the relationship between the NVB in VIBE and the mandibular canal in CT images.

RESULTS

The visibility of the NVBs in plain VIBE was 89%, the same as on CE VIBE. There were three invisible cases in each plain and CE VIBE images. The invisible areas were premolar in three cases, and molar in one case, and the causes of the invisibility were a metallic artefact in one case and motion artefacts in the other two cases.

CONCLUSIONS

A plain VIBE can depict the NVB at the same rate as CE VIBE, and is suitable for detecting NVBs.