Mandibular incisive canal-related prevalence, morphometric parameters, and implant placement implications: a multicenter study of 847 CBCT scans.

BACKGROUND: This study evaluated the epidemiological and morphological features of the mandibular incisive canal (MIC) using cone beam computed tomography (CBCT) in a significant sample of subjects in Brazil. MATERIAL AND METHODS: This retrospective, multicenter study assessed 847 CBCT scans performed at four oral imaging centers. The sample comprised CBCT images acquired from dentate individuals who presented at least from tooth 35 to tooth 45 in the anterior mandible region. Data regarding patient sex and age, and MIC linear measurements (length and diameter in mm), anatomical distances (to the alveolar, buccal and lingual cortexes, inferior border of the mandible, and adjacent teeth apexes), and location were obtained. RESULTS: The MIC was more prevalent in women (76.3% [p<0.001]) between the fourth and sixth decades of life (p<0.001). It was present bilaterally (p<0.001) and exhibited a mean length of 7.7 mm (standard deviation [SD]=3.7 mm). Spearman correlation and logistic regression analysis revealed collinearity between age and linear measurements (p<0.05). The mean distances varied from the initial to the final portion of the MIC, respectively, in relation to the buccal cortex (mean=2.6 mm, SD=1.27; mean=3.96 mm; SD=1.43), to lingual cortex (mean=5.13 mm; SD=1.7; mean=4.61 mm, SD = 1.65), and to the inferior mandibular border (mean = 9.32 mm, SD=1.92; mean=8.76 mm, SD=2.07 mm). The difference in the proximity of the MIC to the apex of the inferior lateral incisor was statistically significant (p<0.05). CONCLUSIONS: Results of this study revealed a high prevalence of MIC with a bilateral pattern in women who were between the fourth and sixth decades of life. Both the distance between the MIC and the lingual cortex of the mandibular alveolar bone, and the diameter of the MIC, decreased as its trajectory assumed a more anterior position.

Infrared thermography assessment of patients with temporomandibular disorders.

OBJECTIVES: To assess patients with and without temporomandibular disorders (TMD) infrared thermography according to the differences in thermal radiance using quantitative sensitivity and specificity tests; and to evaluate the thermal asymmetry and the correlation of the thermal intensity with the intensity of pain upon palpation. METHODS: This cross-sectional study performed a quantitative evaluation of clinical and thermographic examinations. The volunteers were evaluated for the presence of TMD using RDC/TMD (Diagnostic Research Criteria for Temporomandibular Disorders), and were divided into two groups: TMD group (n = 45); control group (n = 41), composed of volunteers without TMD, according to the Fonseca Anamnestic Index. The images were assessed for selected regions of interest for the masseter, anterior temporal and TMJ muscles. The mean values ​​of the areas of both groups were compared under the receiver operating characteristic curve. Spearman correlation analysis (non-parametric data) between pain level and mean temperature, by region, and the Pearson's χ2 test was used to verify the association between the presence of temperature and pain asymmetry. The level of significance was set at p < 0.05. RESULTS: Both Groups, with and without TMD, presented with absolute and non-dimensional mean temperature without statistical differences (p>0.05). When correlating temperature with intensity of pain upon palpation, a negative correlation was observed for the masseter muscle. CONCLUSION: Infrared Thermography resulted in low area under the curve, making it difficult to differentiate TMD via thermographic analysis. The intensity of pain upon palpation in patients with TMD may be accompanied by a decrease in local temperature.

Assessment of artefacts produced by metal posts on CBCT images.

AIM: To evaluate artefact intensity in cone beam computed tomography (CBCT) images of two alloys used in metal posts scanned using different exposure parameters. METHODOLOGY: The sample consisted of 20 single-rooted teeth divided into two groups for use with either a NiCr post or AgPd post. All teeth were scanned with and without their corresponding metal posts and with and without the presence of an extra restored tooth in the arch. The samples were scanned using CS 9000 3D scanner with two exposure protocols: 85 kV 6.3 mA and 85 kV 10 mA. Voxel size and FOV were fixed at 0.100 mm and 5 cm × 3.75 cm. The presence of artefacts was assessed qualitatively by two calibrated observers using the CBCT volume and paired 2D images, and quantitatively by one trained observer, using ImageJ software. Wilcoxon's signed rank, Mann-Whitney, kappa and chi-square tests were used for qualitative analyses. Two-way anova and Tukey's tests were used for quantitative analyses. All analyses were conducted considering the 95% confidence level (α < 0.05). RESULTS: For the CBCT volume qualitative analysis, significant differences were observed between the metal alloys in the presence of an extra restored tooth, with higher artefact intensity for AgPd when assessing hypodense halos and lines (P = 0.006). Images with two restored teeth had significantly more hypodense and hyperdense lines (P = 0.033). When evaluating exposure parameters and number of restored teeth, the paired image quality analysis revealed significant disagreement between observers for diagnostic image quality (P = 0.001). Quantitative artefact analysis revealed higher artefact intensity for the AgPd posts in the presence of two restored teeth. CONCLUSION: Although the exposure parameters tested did not interfere with artefact intensity, post alloys with a higher atomic number and the presence of another metal structure in the arch increased artefact intensity and impaired the diagnostic quality of CBCT images.

Influence of exposure parameters on the detection of simulated root fractures in the presence of various intracanal materials.

AIM: To investigate how the exposure parameters used when producing CBCT scans affect diagnostic accuracy when detecting simulated vertical root fractures and how various filling materials affect image quality. METHODOLOGY: A total of 160 extracted single-rooted human teeth were divided into four groups based on the materials within the root canals: unrestored, gutta-percha, metallic post and fibreglass post. Half of the sample of each group was selected for the induction of vertical root fractures. Each tooth was placed in an empty socket of a dry skull which was scanned on a CBCT unit (9000 3D scanner; Kodak Dental Systems, Carestream Health, Rochester, NY, USA) using the following exposure parameters: 74 kV/12 mA; 74 kV/10 mA; 74 kV/8 mA; 74 kV/6.3 mA; 70 kV/12 mA; 70 kV/10 mA; 70 kV/8 mA; 70 kV/6.3 mA. Two observers assessed all images using a 5-point confidence scale for fracture detection and a 4-point score for the presence of artefacts. Sensitivity, specificity, accuracy and area under ROC curve were compared by two-way anova and Tukey's test. Artefact formation was evaluated by descriptive statistics. RESULTS: There were no significant differences in the sensitivity (P = 0.370), specificity (P = 0.660), accuracy (P = 0.084) and area under the ROC curve (P = 0.674) values amongst the various exposure parameters within the same group. There were some significant differences when the groups were compared for each intracanal material. The sensitivity and accuracy of the group containing metallic posts were significantly lower than the unrestored and fibreglass post groups (P ≤ 0.017). CONCLUSION: The variations in exposure parameters did not interfere with the diagnosis of vertical root fractures, independent of the root canal restorative status. Metallic posts were associated with greater artefact formation and compromised the diagnostic performance. It is possible to decrease the kVp/mA settings to reduce the probability of biological effects due to radiation, without losing diagnostic accuracy.

Correlation between temporomandibular joint morphology and disc displacement by MRI.

OBJECTIVES: The aim was to evaluate the morphology of the temporomandibular joint's (TMJs) disc and condyle as well as its correlation with disc displacement, using MRI. METHODS: 190 TMJs were retrospectively analysed. The condyle morphology of each TMJ was evaluated by two observers using both axial and coronal views, as were their disc morphology and displacement, using sagittal view. Condyle morphology was classified as flat, convex, angled or rounded in the coronal sections and as anterior side flat/posterior side convex, biconvex, anterior side concave/posterior side convex, flat or biconcave in the axial view. Disc morphology was determined as biconcave, biplanar, biconvex, hemiconvex or folded. χ2, Fisher exact and Bonferroni correction tests were used to evaluate the data. ANOVA followed by post hoc Tukey's test was used to evaluate the interaction between age and disc displacement. RESULTS: Anterior disc displacement with reduction; convex condyle morphology in the coronal view; anterior side concave/posterior side convex morphology in the axial view; and biconcave discs were found to be the most prevalent findings. An association was observed between disc morphology and disc displacement (p<0.001). No correlation between condyle morphology and TMJ disc displacement was found (p=0.291 for axial and p=0.14 for coronal views). CONCLUSIONS: The results of this study suggest that TMJ disc morphology is associated with disc displacement.

Magnetic resonance imaging findings of true bifid mandibular condyle with duplicated mandibular fossa.

Bifid mandibular condyle (BMC) is a rare asymptomatic morphological alteration with no predilection for age group or gender. Its morphology varies from a shallow groove to two condylar heads with separate necks, oriented mediolaterally or anteroposteriorly. This report describes an unusual case of anteroposterior bifid condyle in a 39-year-old female patient with the main complaint of mouth-opening limitation and a deviation of the mandible to the left side. Magnetic resonance imaging (MRI) findings revealed a bifid condyle on the left side and duplicated mandibular fossa, with the articular disc over the anterior head. The MRI images in the open-mouth position revealed minimal movement of the condyle. Despite the increased number of mediolateral bifid mandibular condyle cases described in the literature, none of previously reported cases of BMC included an anteroposterior bifid condyle case with two distinct mandibular fossa.

Comparison of digital systems and conventional dental film for the detection of approximal enamel caries.

OBJECTIVES: The aims of this study were (1) to compare the accuracy of the detection of approximal enamel caries lesions using three intraoral storage phosphor plate digital systems and one conventional film-based radiographic system; and (2) to determine whether there is a correlation between the histological and radiographic measurements of enamel caries. METHODS: 160 approximal surfaces were radiographed under standardized conditions using three storage phosphor stimulable systems (DenOptix and Digora FMX with white and blue plates), and one film system (Insight film). 17 observers scored the images for the presence and depth of caries using a 4-point scale. The presence of caries was validated histologically (gold standard). Two-way analysis of variance was used to test the differences in sensitivity, specificity and overall accuracy (TP + TN). The data from the radiographic and histological measurements were statistically analysed by Spearman's rank correlation coefficient. RESULTS: Two-way analysis of variance and the post hoc t-test demonstrated that Digora (white plate) had higher specificity and overall accuracy values than DenOptix (P = 0.021); there was no statistically significant difference among the other imaging modalities (P > 0.05). There was no significant correlation between the histological depth measurements and the radiographic measurements from Digora (blue plate) (P = 0.43), Digora (white plate) (P = 0.15), DenOptix (P = 0.17) and Insight film (P = 0.06). CONCLUSIONS: The results suggest that (1) the performance of the three storage phosphor image plate systems was similar to that of the Insight film for detection of approximal enamel caries, and (2) the increase in histological depth of enamel caries was not significantly correlated with radiographic measurements.

Effect of alternative photostimulable phosphor plates erasing times on subjective digital image quality.

OBJECTIVE: To evaluate the influence of alternative erasing times of DenOptix(R) (Dentsply/Gendex, Chicargo, IL) digital plates on subjective image quality and the probability of double exposure image not occurring. METHODS: Human teeth were X-rayed with phosphor plates using ten different erasing times. Two observers evaluated the images for subjective image quality (sharpness, brightness, contrast, enamel definition, dentin definition and dentin-enamel junction definition) and for the presence or absence of double exposure image. Spearman's correlation analysis and ANOVA was performed to verify the existence of a linear association between the subjective image quality parameters and the alternative erasing times. A contingency table was constructed to evaluate the agreement among the observers, and a binominal logistic regression was performed to verify the correlation between the erasing time and the probability of double exposure image not occurring. RESULTS: All 6 parameters of image quality were rated high by the examiners for the erasing times between 25 s and 130 s. The same erasing time range, from 25 to 130 s, was considered a safe erasing time interval, with no probability of a double exposure image occurring. CONCLUSIONS: The alternative erasing times from 25 s to 130 s showed high image quality and no probability of double image occurrence. Thus, it is possible to reduce the operating time of the DenOptix(R) digital system without jeopardizing the diagnostic task.