Relationships between third-molar juxta-apical radiolucencies and mandibular canals in panoramic and cone beam computed tomography images

The influence of age, sex, and tooth type on the anatomical relationship between tooth roots and the mandibular canal

Purpose

Cone-beam computed tomography (CBCT) reconstructions were analysed to elucidate factors affecting the anatomical relationship between tooth roots and the mandibular canal(MC).

Materials and Methods

Images of 300 volumetric tomography scans of patients aged between 20 and 79 years old (167 women and 133 men) were analysed. The mean distances between 2,053 dental root apices and the internal border of the MC were obtained by measuring the horizontal and vertical distances on coronal CBCT images. The actual distance was then calculated mathematically with the Pythagorean formula. The statistical significance of differences between men and women was assessed using the Mann-Whitney test. Correlations with patient age were evaluated with the Spearman rank correlation coefficient.

Results

The mean distances ranged from 2.17 mm, for single right third molar roots in women, to 8.02 mm for single left third molar mesiolingual roots in men. The mean distances measured for the mandibular right second molar mesial roots and the right second premolar roots were larger in men than in women. Age showed a significant positive correlation with the measured distances for mesial and distal roots of the first and second molar on both sides and the right third molar, mesiolingual roots of the left third molar, and single roots of the right third molar.

Conclusion

The root-to-mandibular canal distance depended on age and the type of tooth. In 2 root types, this distance was impacted by sex.

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.

Appearance of Mandibular Para-radicular Third Molar Radiolucencies on Cone-Beam Computed Tomography

Aims:

Mandibular para-radicular third molar radiolucencies (MPRs) may be mistaken for pathological lesions, leading to misdiagnosis and mistreatment. This study sought to assess the appearance of MPRs on cone-beam computed tomography (CBCT).

Settings and Design:

This was a descriptive, cross-sectional study.

Materials and Methods:

This study evaluated 770 CBCT of patients presenting to the dental school of Hamadan University of Medical Sciences. Demographic information, unilateral or bilateral presence, shape and prevalence of MPRs observed on axial and sagittal sections, their density, thinning of cortical margin, internal trabeculation, bony expansion, and mean height and width of MPRs were all evaluated.

Statistical Analysis Used:

Data were analyzed using SPSS version 22.0 and descriptive statistics. Chi-square test was used.

Results:

Seventy (9.1%) patients had a total of 82 MPRs, including 51 (72.86%) females. The prevalence of MPRs in females was more than males (P = 0.011). The majority of MPRs were unilateral 58 (70.73%), mostly round in shape 48 (58.54%), and were mostly associated with third molars with distoangular impaction 47 (57.31%); this difference was statistically significant (P < 0.001). Furthermore, in 47 (57.32%) patients, MPRs had less density than the surrounding bone. MPRs were not associated with expansion or root resorption in any patient.

Conclusion:

Differentiation of MPRs from the pathological lesions is important to make a decision about further imaging or referral for surgical treatment. MPRs are often considered normal since they do not cause root resorption or bone expansion and do not affect the lamina dura. MPRs are more commonly found adjacent to third molars with distoangular impaction.

The anatomical relationship between the roots of erupted permanent teeth and the mandibular canal: a systematic review

PURPOSE

This study reviewed the literature on the position of the mandibular canal (MC) relative to the root apices (RA) of neighbouring teeth using cone beam computed tomography (CBCT).

METHODS

The authors searched the PubMed, Scopus, EBSCO Dentistry and Oral Sciences Source, Cochrane and Lilacs databases for relevant English-language articles with no year limitations published through January 25, 2018.

RESULTS

The search identified 888 articles, 12 of which met the inclusion criteria. Three groups were found based on the measuring method: the shortest distance from the RA to the MC, the vertical distance from the RA to the MC, or the distance from the RA to the superior cortical bone of the MC. In the first and second groups, the shortest distances to the canines, first premolars, second premolars, first molars, second molars, and third molars were 3.8 mm, 4.76 mm, 1.65 mm, 1.23 mm, 0.64 mm, and 1.28 mm, respectively. In the third group, the shortest distances to the second premolars, first molars, and second molars were 2.71 mm, 3.82 mm, and 1.4 mm, respectively.

CONCLUSIONS

The distance from the MC to the RA was generally shorter in females and younger people, with decreasing distances in patients over 60 years old, and depended on the tooth type.

TRIAL REGISTRATION

The protocol for this systematic review was registered on PROSPERO (CRD42018085478).

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.