Evaluation of retromolar space for mandibular molar distalization: A retrospective cross-sectional CBCT study of vertical skeletal patterns and panoramic diagnostic accuracy.

To analyze the mandibular retromolar space among normal-divergent adult patients with different sagittal skeletal patterns by cone-beam computed tomography (CBCT). CBCTs of a total of 120 normal-divergent adult patients were investigated. Patients were categorized into the following three groups according to their ANB angle: skeletal Class I (48 patients), skeletal Class II (36 patients), and skeletal Class III (36 patients). Four different planes parallel to the mandibular occlusal plane were used to measure the retromolar space. The retromolar space was measured by two reference lines and then compared between different sagittal skeletal patterns groups. The incidence of root contact with the inner lingual cortex was compared among the three groups. The retromolar space of the Class III patients was significantly larger than that of Class I patients and Class II patients. Compared with Class I and Class III patients, Class II patients had a smaller retromolar space and higher incidence of contact with the inner cortex of the mandible. Class III patients had a larger retromolar space than Class I patients and Class II patients in four different planes. The mandibular retromolar space should be evaluated by CBCT in patients who need mandibular molar distalization.

The aim of this study was to compare the difference in length and width of the mandibular retromolar space (RMS) stratified by the different eruption and impaction statuses of the third molars in patients with skeletal Class I malocclusion. The right mandibular RMS in 186 adult patients categorized according to the different statuses of the third molar was analyzed by using cone-beam computed tomography (CBCT). The shortest distances between the inner lingual cortex of the mandibular body and second molar root were measured parallel to the posterior occlusal line (POL) at depths of 2, 4, 6, 8, and 10mm (mandibular retromolar space length in root level, RLin2,4,6,8,10) on the axial slices with the cementoenamel junction (CEJ) as the reference level. The width of the RMS and second molar root was measured vertical to the POL at the terminal point of the molar distalization at depths of 2, 4, 6, 8, and 10mm (width of the mandibular retromolar space, BW2,4,6,8,10/ width of the second molar distal root, TW2,4,6,8,10) from the CEJ. RL in different measurement planes was 2.72 ± 2.22 ~ 3.74 ± 2.26 for Group A, 5.27 ± 1.68 ~ 9.10 ± 2.04 for Group B, 1.94 ± 2.34 ~ 5.71 ± 4.37 for Group C, 1.83 ± 2.95 ~ 5.05 ± 4.24 for Group D, and 5.93 ± 3.97 ~ 10.52 ± 2.16 for Group E. The BW measurement results for A ~ E group were 9.71 ± 1.41 ~ 10.51 ± 1.81, 9.83 ± 1.39 ~ 12.55 ± 2.11, 9.96 ± 1.21 ~ 12.17 ± 1.62, 9.82 ± 1.47 ~ 12.28 ± 2.77, and 10.02 ± 1.20 ~ 12.75 ± 0.82, respectively. There was no significant difference between men and women in any measurements (P > 0.05). Patients with normal third molars erupted and those vertically impacted possessed larger RMS lengths than those in which the third molars were missing, horizontally impacted or mesially impacted (P < 0.05). In each measurement plane, TW was significantly smaller than BW (P < 0.05). Sex had no effect on the length or width of the mandibular RMS. Different statuses of third molars can also differentially affect the mandibular RMS. The mandibular RMS width is not a limit for mandibular molar distalization. When considering the distalization of mandibular molars, more attention should be directed to the lingual cortex of the mandible, and CBCT scans are recommended for patients who require significant mandibular molar distalization. The mandible buccal shelf and retromolar area maybe a safe zone to insert the miniscrew for molar distalization.

Objective. To compare the diagnostic accuracy of panoramic imaging, stereo-scanography and cone beam computed tomography (CBCT) for assessment of mandibular third molars. Material and methods. One hundred and twelve patients (147 third molars) underwent radiographic examination by panoramic imaging, stereo-scanography and CBCT. Tooth angulation, root morphology, number of roots and relation to the mandibular canal were assessed. The same variables were assessed intra- and post-operatively and served as reference for the radiographic assessments. The diagnostic accuracy for each variable was compared between the three modalities and accuracy was further expressed as sensitivity and specificity and tested between the modalities for identifying the relation to the mandibular canal. Results. There were no significant differences between the modalities regarding tooth angulation, root morphology and number of roots. However, CBCT was more accurate than stereo-scanography for determining root bending in the bucco-lingual plane (p = 0.02). Moreover, sensitivity for direct contact to the mandibular canal (panoramic imaging: 0.29, stereo-scanography: 0.57, CBCT: 0.67) was higher for CBCT than for panoramic images (p = 0.05) and specificity for no direct contact to the mandibular canal (panoramic imaging: 0.78, stereo-scanography: 0.53, CBCT: 0.68) was higher for panoramic images and CBCT than for scanograms (p < 0.001). Conclusion. Panoramic imaging, stereo-scanography and CBCT seem equally valuable for examination of tooth angulation, number and morphology of roots of mandibular third molars. However, CBCT was more accurate for assessment of root bending in the bucco-lingual plane and more accurate than panoramic images to identify direct contact to the mandibular canal.

To investigate the differences in mandibular retromolar space among skeletal Class I subjects with different vertical divergence using cone-beam computed tomography (CBCT). A total of 123 skeletal Class I patients (aged 20-40 years) were categorized into hypodivergent, normodivergent, and hyperdivergent groups based on S-N/Go-Me and facial height index (FHI). Mandibular retromolar space was measured at four planes parallel to the occlusal plane along the sagittal line and molar cuspal line, respectively. The mandibular retromolar space was compared among the three vertical groups. The hyperdivergent group had a significantly smaller mandibular retromolar space compared with the other two groups, while the hypodivergent group had the largest retromolar space. In addition, the hyperdivergent group had a larger number of subjects whose roots contacted the lingual cortex of the mandibular body. The hyperdivergent group tends to exhibit the smallest mandibular retromolar space and highest risk of cortex contact. Clinicians should keep in mind that successful molar distalization requires sufficient retromolar space, especially for hyperdivergent subjects, which should be verified with CBCT.

We aimed to compare the effectiveness of panoramic radiography (PR) and cone beam computed tomography (CBCT) in radiographic diagnosis of maxillary sinus (MS) diseases. MS diseases (mucosal thickening, mucus retention cyst, polyp sinusitis, mucocele and tumoral formations) was carried out on both PR and CBCT images belonging to 625 patients. Analyzes were performed separately for right and left maxillary sinus, and total of 1250 PR and CBCT images. While a diagnosis of disease was made in 42.96% of a total of 1250 MS according to CBCT. According to PR, diagnosis was made in 58.72%. The 537 diagnoses where lesion presence was determined on CBCT in our study were compared over PR, and it was observed that, there was the right diagnosis (true positive) in 106 (19.73%) of these including respectively mucus retention cyst (n = 88), polyp (n = 16), 1 sinusitis and 1 tumor, and there was an incorrect diagnosis (false positive) in 221 (41.15%). In 42.92% of the MS that were identified as healthy based on CBCT, the correct diagnosis was also made on PR (true negative). The use of CBCT instead of PR in the diagnosis of pathological or inflammatory diseases contributes to a more accurate radiographic differential diagnosis.

Alveolar bone loss (ABL) and periodontal lesions are common diseases that have an undeniable effect on teeth maintenance and health. Current diagnostic methods include probing, intraoral radiography, and panoramic radiography; each has its limitations. In this study, we aimed to assess the diagnostic accuracy of panoramic radiography in the diagnosis of interdental ABL. In this cross-sectional study, panoramic and cone-beam computed tomography (CBCT) images from 80 patients were collected from the archives of an oral and maxillofacial radiology center. The amount of ABL was obtained by measuring the distance from the Cemento-Enamel Junction (CEJ) to the alveolar bone crest on both panoramic and CBCT images. Patients were divided into healthy (ABL ≤ 2 mm) and diseased (2 mm < ABL) groups in terms of periodontal disease. There was no statistically significant difference in the average ABL in the premolar, maxillary molar, and mandibular molar areas between the two techniques. However, in other areas, the ABL size was significantly lower in the panoramic view (p < 0.05). Also, the panoramic technique correctly recognized 89.1% of normal and 88.4% of ABL cases. The overall accuracy of panoramic radiography in the diagnosis of ABL was 85%, indicating the good accuracy of this technique. In maxilla, the highest diagnostic accuracy of the panoramic technique was in the molars, and the lowest was in the incisors. In the mandible, the highest and lowest diagnostic accuracy of the panoramic technique was related to molars and premolars, respectively. According to the kappa statistic, there was a significant good to very good agreement between the two types of techniques in all maxillary areas (p < 0.001). Panoramic radiography is accurate in showing ABL. Measuring ABL in the posterior mandibular areas in panoramic radiographs is quite reliable; however, in general, digital panoramic radiography shows less ABL than the actual amount.

In the current literature, cone beam computed tomography (CBCT) seems to be more accurate in detecting apical lesions (AL) than two-dimensional radiographs. Cortical bone thickness might have an influence on AL visibility. Therefore, the purpose of the study was to directly compare the diagnostic accuracy of panoramic radiography (PANO) and CBCT in detecting AL in the upper jaw and determine the influence of cortical bone thickness on AL visibility. Anonymised digital images of 351 patients who received a CBCT image and a panoramic radiograph within 90days were examined for AL in the upper jaw. The analysis was conducted by a trained examiner and reviewed by an expert in dental radiology. Further, the dimensions of AL and cortical bone thickness in the region affected by AL were measured to determine their influence on visibility. Statistical analysis was carried out by means of statistical software (IBM SPSS 25; Armonk, NY, USA). The mean age of the patients was 58.9years with an almost equal gender distribution. A total of 2223 teeth in the upper jaw were included in the final analysis. CBCT detected AL on 144 teeth (6.5%), of which only 23 were also visible on a PANO. The difference between both methods was significant (p < 0.001). The dimensions of AL measured within a PANO were approximately twice as high as those measured by CBCT. However, the difference was not significant (p ≥ 0.005). Cortical bone thickness had no influence on AL visibility. Panoramic radiographs are unsuitable for a reliable diagnosis of AL in the upper jaw, while CBCT leads to a better visualisation of AL. Bone thickness has no significant influence on AL visibility with either imaging method.

BackgroundThe anatomical position of the mandibular third molars (M3s) is located in the distal-most portions of the molar area. In some previous literature, researchers evaluated the relationship between retromolar space (RS) and different classifications of M3 in three‑dimensional (3D) cone—beam computed tomography (CBCT).MethodsTwo hundred six M3s from 103 patients were included. M3s were grouped according to four classification criteria: PG-A/B/C, PG-I/II/III, mesiodistal angle and buccolingual angle. 3D hard tissue models were reconstructed by CBCT digital imaging. RS was measured respectively by utilizing the fitting WALA ridge plane (WP) which was fitted by the least square method and the occlusal plane (OP) as reference planes. SPSS (version 26) was used to analyze the data.ResultsIn all criteria evaluated, RS decreased steadily from the crown to the root (P < 0.05), the minimum was at the root tip. From PG-A classification, PG-B classification to PG-C classification and from PG-I classification, PG-II classification to PG-III classification, RS both appeared a diminishing tendency (P < 0.05). As the degree of mesial tilt decreased, RS appeared an increasing trend (P < 0.05). RS in classification criteria of buccolingual angle had no statistical difference (P > 0.05).ConclusionsRS was associated with positional classifications of the M3. In the clinic, RS can be evaluated by watching the Pell&Gregory classification and mesial angle of M3.

The aim of this study was to assess the effects of twin block functional appliance three dimensionally on mandibular third molars angulation and eruption space. This retrospective study included cone beam computer tomography (CBCTs) of 34 Class II females (11.84 ± 0.94 years) who were divided into 2 groups. The first group received a standard twin block appliance (intervention group), while the other was considered as a control. CBCT images were obtained for all patients before the start of the intervention (T0) and after the active phase (9.4 ± 1.33 months) in the intervention group and at the beginning (T0) and after the observation period (T1) in the control group (8.12 ± 2.72 months). Measurements for the retromolar space were performed on the axial views, while those for molar angulation were performed on sagittal views as well as CBCT panoramic reformatted images. Both twin block and control groups showed non-significant changes in the angular measurements (sagittal L8/MP° and panoramic L8/MP°) denoting lack of change in the angulation of the third molars in relation to the mandibular plane after treatment. On the other hand, retromolar spaces showed a statistically significant increase (P ≤ .05) in both groups. The change was much significant for the twin block group, measuring 1.95 mm and 1.56 mm on the right and left sides, respectively, as compared to the control group which revealed less than 1 mm increase in the retromolar space on both the right and left sides. In spite of their positive impact on the retromolar space, twin block bite jumping appliances have a non-significant influence on the angulation of the developing mandibular third molars.

To interpret a correlation between buccolingual inclination of molars and palatal depth in hyperdivergent patients and to identify importance of determining inclination of molars in assessing transverse discrepancies (as skeletal or dental). This was a retrospective cone beam computed tomography (CBCT) study. The study was conducted in the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. This was a retrospective CBCT study of 79 patients who underwent diagnostic CBCT for treatment purposes. The CBCT scans were evaluated systematically and the required parameters were accessed with suitable reference planes. Student's t-test (95% confidence interval) was performed to determine buccolingual inclination of first molars between the right and left sides. Only patients with a vertical growth pattern and skeletal class I relation were included and they were classified into three groups based on their palate depth. In patients with palatal depth > 22 mm, the mean inclination of molars was 7.4°; with palatal depth in the range of 19-22 mm, the mean inclination of molars was 5.23°; and with palatal depth < 19 mm, the mean inclination of molars was 2.9°. Results showed that there was a significant correlation between the buccolingual inclination of molars and the palate depth in vertical growers (P < 0.05). The buccolingual inclination of first molars is increased in patients with greater palatal depth. This parameter is helpful in classifying crossbites as skeletal or dental. The amount of compensation required to correct the cross bite can be adjusted using Korkhaus Index.

BackgroundThis study aims to evaluate the reliability of panoramic imaging in assessing styloid process (SP), using cone beam computed tomography (CBCT) as the reference standard. CBCT is preferred for assessing SP as it displays the dimensions and morphology of the SP without superimpositions.MethodsSP elongation, calcification type (type 1: elongated, type 2: pseudoarticulated, type 3: segmented, and type 4: distant), and calcification pattern (calcified outline, partially calcified, nodular, and completely calcified) were evaluated on both panoramic and CBCT images of the same 407 patients. All measurements were recorded for the left and right sides independently. The efficacy of panoramic imaging in assessing SP was analysed through sensitivity, specificity, positive predictive value, and negative predictive value, accompanied by their 95% confidence intervals, with a significance threshold of about 0.05 for all studies.ResultsThere were 113 (27.8%) male and 294 (72.2%) female, for a total of 407 patients with a median age of 43 years (18–69). The prevalence of elongated SP was 43.5% in panoramic images, whereas in CBCT images, it was 52.6%. When compared to CBCT imaging, panoramic imaging exhibited good specificity, with values of 81.2% on the right side and 83.7% on the left side, but demonstrated low sensitivity, recording 67.3% on the right side and 64.4% on the left side.ConclusionsAlmost one-third of the elongated SP cases were detected as false negative in panoramic images. Considering these findings, it is advisable to assess the region using CBCT in situations where SP examination is critical.

To investigate diagnostic accuracy of panoramic radiography in detecting maxillary sinus floor septa by means of a multi-observer receiver operating characteristic (ROC) analysis and a standardized protocol for reporting (STARD protocol; Clin Chem 49(1):1-6, 2003). From our database, 25 cone beam computed tomographies (CBCTs) were selected with one maxillary sinus floor septum (height ≥2.5 mm). For the same patient, a recent panoramic radiograph (PAN) had to be available in the database. As controls, 28 CBCTs plus corresponding PANs without evidence of a sinus septum were selected. Using the CBCTs as ground truth, 17 observers from our dental school on a five-point confidence scale rated both sinuses in all 53 PANs with respect to presence/absence of a sinus septum. Areas beneath ROC curves (Az-values), sensitivity/specificity (SNT/SPF), positive/negative predictive values (PPV, NPV), and positive/negative likelihood ratios (LR+, LR-) were computed for each observer and pooled over all observers. Inter-rater reproducibility was assessed by means of the intraclass coefficient (ICC) using a two-way random effects model. A pooled Az-value of 0.839 was observed (SNT 84.6%, SPF 73.5%). PPV ranged between 0.492 and 0.824 (median 0.627) and NPV between 0.838 and 0.976 (median 0.917). A median LR+ of 3.567 was computed (LR- median 0.193). Inter-rater reliability revealed an ICC of 0.55 (95% confidence interval 0.48 to 0.62). Our results indicate that PAN is a moderately accurate method for sinus elevation planning for the purpose of septum detection. Ruling out a septum by PAN seems to work more accurately than ruling in. For the purpose of maxillary sinus floor septa detection, panoramic radiography can be relatively safely advocated, particularly for judgment of a septum-free sinus.

Is Panoramic Radiography an Accurate Imaging Technique for the Detection of Endodontically Treated Asymptomatic Apical Periodontitis?

A 3-dimensional evaluation of available retromolar space for the application of ramal plates

BackgroundLower third molars (L3M) are the last teeth to erupt in the oral cavity. Uneruption of these teeth still raises questions about its causes, in the literature (1) genetic factors, (2) dental lamina activity and, mainly, (3) insufficient growth and development of the bone bases are included. While the lack of space theory influenced by mandibular morphology and size of L3M was argued to be the main reason for L3M impaction, there is a limitation in the literature in examining such association using more accurate tomographic analysis obtained from CBCT. This work aimed to evaluate the relationship between mandibular morphology and the eruption of L3M.MethodsIn this regard, 85 Cone Beam Computed Tomographies (CBCT), with 147 L3M, were selected from the archives of the Department of Surgery, Stomatology, Pathology and Radiology, Bauru School of Dentistry, obtained using an Accuitomo® Morita device and using the Dolphin Imaging 11.9 software. L3M eruption was related to linear measurements of jaw length (Co-Gn), retromolar space dimension (D2R), mesiodistal width of the L3M crowns, mandibular first molars (L1M) and mandibular canines (LC) and the angle mandibular (Ar-Go-Me). Independent samples t-test, chi-square tests and logistic regression were performed adopting a significance level of 5%.ResultsThe average mandible length of 116.446 mm + 6.415 mm, retromolar space of 11.634 mm + 2.385 mm, mesiodistal size of the L3M of 10.054 mm + 0.941 mm, sum of the mesiodistal widths of the L1M and LC of 15.564 mm + 1.218 mm and mandibular angle of 127.23° + 6.109. There was no statistically significant association between these factors and the eruption.ConclusionWith the results obtained in this study, we conclude that the length and angle of the mandible, teeth size and dimension of the retromolar space are not associated with the L3M eruption.