Accuracy and Reliability of Orthopantomogram and Cone Beam Computed Tomography in Assessing Mandibular Buccal Shelf Anatomy Across Various Skeletal Malocclusions and Vertical Growth Patterns

This study was aimed at determining the specific signs of close relationship between impacted mandibular third molar (IMTM) root and inferior alveolar nerve (IAN) canal as visualised on digital panoramic radiograph or orthopantomograph (OPG) which should indicate as well as contraindicate the need for cone beam computed tomography (CBCT) imaging based on hierarchical model of Fryback and Thornbury. The sample consisted of 120 individuals (200 IMTM) who had undergone OPG as well as CBCT imaging as preoperative radiographic evaluation before surgical extraction. On panoramic radiographs; Rood and Sheehab's radiographic signs of IMTM root and IAN canal, impacted third molar position based on Winter's classification and depth of impaction based on Pell and Gregory's classification were evaluated. On CBCT; presence/absence of corticalization and the status of the buccal and lingual cortices (thinning/perforation) were evaluated. These findings of OPG were compared to CBCT findings to determine the better modality based on hierarchical model of Fryback and Thornbury. Statistically significant association was found between radiographic signs of Rood and Sheehab such as 'no relation' and 'superimposition' on OPG and presence of corticalization between IMTM root and IAN canal on CBCT. Statistically significant association was also found between 'mesioangular' and 'vertical' positions of Winter's classification as well as 'class 1A' of Pell and Gregory's classification of IMTM on OPG and presence of corticalization on CBCT. CBCT was found to be having lesser variance and greater F value as compared to OPG for evaluation of IMTM. On OPG; Rood and Sheehab's radiographic signs such as 'no relation' and 'superimposition', Winter's 'mesioangular' and 'vertical' and Pell and Gregory's 'Class 1A' are not indicative for CBCT examination before surgical extraction is attempted. On OPG; Rood and Sheehab's radiographic signs such as interruption of white line, darkening of root, darkening of canal, deflection of root, narrowing of canal as well as diversion of canal are all frequently associated with absence of corticalization between IMTM root and IAN canal and hence require CBCT examination before surgical extraction is attempted so that post-operative neurological complications can be minimised. Also, Winter's horizontal, distoangular and others as well Pell and Gregory's classes 1B,1C,2A,2B,2C,3A,3B,3C are indicative for CBCT examination before surgical extraction is attempted. Fryback and Thornbury model-based comparison proves that CBCT is a better radiographic modality as compared to OPG for evaluation of IMTM relation with IAN canal.

BackgroundThe 3D position of the mental foramen (MF) is of significant clinical value in dental implantology and mandibular surgeries or in local anesthesia. Despite its importance, it is not clearly known how the position of MF can alter in different individuals, since the literature on the associations between the MF position with vertical growth patterns is non-existent and those on links between the MF position and skeletal malocclusions are scarce. Therefore, we aimed to investigate these, for the first time, on cone-beam computed tomographies (CBCTs).MethodsArchival CBCTs of 9 sub-groups (i.e., 3 skeletal Classes I, II, and III × 3 vertical growth patterns ‘long face, short face, normal face’) were collected by evaluating patients’ SNA, SNB, ANB, facial angle, lower facial height, and FMA (n = 9 × 40 = 360). Included cases were older than 17 years and without any history of orthodontic/orthognathic treatments (243 women, 117 men, mean age: 22.28 ± 2.80 years). Perpendicular distances between the MF and 3 fixed bony structures (the mandibular symphysis [S/width], the mandibular ramus [R/length], and the mandibular lower cortex [C/height]) were measured on different sectional planes on both hemimandibles. Left- and right-side measurements were combined. Data were analyzed using the 3-way ANCOVA, Bonferroni, one-way ANOVA, Tamhane, Pearson, and t-test (α = 0.05).ResultsWidth was the smallest in Class II and greatest in Class III cases (all P values < 0.000001, Bonferroni). It was the shortest in long faces and longest in short faces (all P values ≤ 0.00008). The inferior-superior height was larger in Class III than both Classes I and II (both P values ≤ 0.003); there was no significant difference between Classes I and II in terms of height (P = 0.684). Height was the largest in long faces and smallest in short faces (all P values < 0.000001). The anterior-posterior length was the largest in Class III and smallest in Class II (all P values < 0.000001). Length was larger in short-face people versus normal- or long-face individuals (P ≤ 0.00003); nevertheless, long and normal faces did not differ in terms of length (P = 0.448). Subjects’ age was not correlated with their MF positions (P ≥ 0.579, Pearson coefficient). Sex dimorphism existed only for height (P = 0.009, t-test) but not for length or width.ConclusionsThe MF position may considerably differ in various horizontal or vertical growth patterns and sexes. This should be noted in mandible surgeries.

The objective of the research was to evaluate the location, size, variability, and morphologic features of mental foramen (MF) and the inferior alveolar nerve canal (IAN) on cone-beam CT. We evaluated the morphologic findings of mental foramen (MF) and inferior alveolar nerve (IAN) canal of 88 mandibular hemiarches of 65 Caucasian subjects (35 males, 30 females; age range 25-75 years) using cone beam CT. The most common horizontal position of MF was type 3 (53.4%), followed by type 4 (39.8%), type 1 (2.3%), type 2 (2.3%), and type 5 (2.3%). Regarding the vertical position, in 71.6% of cases (63/88) we found type 3 position, followed by type 2 (22.7%) and type 1 (5.7%). MF presented as oval in 51.1% and round in 42%, with double oval and triple foramens having been observed in 5.7% and 1.1% respectively. In 36.9% of cases, we found an anterior loop of the IAN. The mean depth of MF was 6.12±1.65mm; width and height were 3.7±0.83mm and 3.14±0.78mm. Width and height of the IAN distal to MF were 2.27±0.53mm and 2.74±0.51mm, while those of the incisive nerve canal mesial to MF were 1.37±0.44mm and 1.54±0.58mm, respectively. An increase in the width of MF was correlated to oval shape (r=0.45; P < 0.01), and there was a low but significant correlation (r=0.23; P < 0.05) between the round shape of MF and the size of the IAN. MF shape appears to be correlated to MF width and size of the IAN. The individual anatomical variability of this structure is a factor that must be considered when dealing with mandibular surgery.

Objective: This study aimed to compare sinus volume and dimensions in patients with high-, low-, and normal-angle vertical growth patterns using cone-beam computed tomography (CBCT).Materials and methods: According to skeletal vertical face growth patterns, 60 adults (31 female, 29 male, average age: 29.90 ± 10.91 years) were divided into three groups equally: high-angle, low-angle, and normal-angle groups. Cephalometric tracings were obtained from CBCT images and SN-GoGn (angle between Sella–Nasion line and Gonion–Gnathion line) cephalometric angular measurements used for the classification of skeletal vertical pattern evaluations. Morphological and dimensional changes in the maxillary sinuses were evaluated on CBCT images. Data were analyzed using the one-way ANOVA, Kruskall–Wallis, and Mann–Whitney U statistical tests.Results: There were no statistically significant differences among the groups in terms of age (p > .05). The low-angle vertical growth pattern group showed significantly better results than the high-angle group in the right maxillary sinus length parameter (p < .05).Conclusion: According to the results, the high-angle subjects showed statistically lower values in terms of maxillary sinus length and width than the low-angle subjects. There were no effects of vertical face development on right and left maxillary sinus volumes. The results of this study may be useful in maxillary sinus evaluation when planning for orthognathic surgery and orthodontic mini screw application in various vertical face patterns.

Objective This study aimed to compare cranial base angulations in subjects with high-angle, low-angle, and normal-angle vertical growth patterns using cone beam computed tomography (CBCT). Design This study is a retrospective clinical research. Settings This study was carried out at the Dentistry Faculty of Eskisehir Osmangazi University. Participants According to skeletal vertical face growth patterns, 78 subjects (48 females and 30 males, average age: 13.19 ± 1.73 years) were divided equally into three groups: high angle, low angle, and normal angle groups. Main Outcome Measures Cephalometric images were derived from CBCT, and patients were classified according to the SN-GoGn angle (sella-nasion, gonion gnathion angle). Sagittal, axial, and coronal cranial base angulations were measured in three-dimensional (3D) CBCT images. Data were analyzed using the Kolmogorov-Smirnov normality, Kruskal-Wallis, and Mann-Whitney U statistical tests. Results There were statistically significant differences between the low-angle and high-angle groups according to sagittal cranial base angulation parameters ( p = 0.01). Conversely, there were no statistically significant differences between vertical facial growth patterns according to coronal and axial cranial angle variables ( p > 0.05). Conclusion According to the study results, there were no effects of cranial base angulations in two planes (coronal and axial) on different vertical skeletal growth patterns. In the sagittal cranial base angulation parameter, the high-angle group showed greater angulation values than the low-angle group. CBCT may be helpful for evaluating, diagnosing, and predicting 3D cranial base differences.

The aim of this study was to evaluate the diagnostic potential of periapical radiograph, panoramic radiograph, and cone-beam computed tomography (CBCT) in detecting implant-related perforation of the inferior alveolar canals. In this ex vivo study, a total of 45 dental implants were placed in 15 sheep hemimandibles simulating two types of injuries to the inferior alveolar canal: pilot drill injury and implant penetration into the canal. Fifteen implants were placed as the control group with 1 mm distance from the inferior alveolar nerve (IAN) canal roof. An imaging phantom was prepared by placing implant-containing blocks in the posterior mandibular area on both sides of an artificial model of the cranium. Panoramic and periapical radiographs as well as CBCT scans were obtained from the imaging phantom. Two independent observers repeated image analysis over two sessions. The area under the receiver operating characteristic curve (AUC) was used to determine diagnostic accuracy. Interobserver and intraobserver agreements were obtained using Cohen's kappa (α = 0.05). For detection of pilot drill injuries by observer 1, CBCT (AUC = 1) and periapical radiograph (AUC = 0.889) were significantly better than using panoramic radiographs (AUC = 0.694) (P < 0.001 and P = 0.014, respectively). For observer 2, CBCT (AUC = 0.897) was also superior to panoramic radiography (AUC = 0.683) for this purpose (P = 0.018). For detection of penetrative injuries to the IAN canal, periapical radiography had an AUC of 0.995 and 0.986 for observers 1 and 2, respectively, while the AUC for panoramic radiography was 0.990 and 0.948 for observers 1 and 2, respectively. The corresponding values using CBCT were 1.000 and 0.995, respectively. No significant difference was observed between the three modalities for detection of penetrative injuries (P > 0.05). CBCT was better in detecting pilot drill injuries to the IAN canal compared to panoramic radiograph. Therefore, in cases where clinical presentations suggest IAN disturbances, CBCT scan should be preferred. However, the diagnostic potential of periapical radiograph, panoramic radiograph, and CBCT was not significantly different for detection of penetrative injuries to the IAN canal.

Objectives The objectives of this article were to analyze the bone thickness and bone depth in the mandibular buccal shelf area at four sites, that is, a mesiobuccal section of mandibular first and second molar and distobuccal section of first and second molar and to analyze the bone thickness and bone height with respect to the spatial position of inferior alveolar nerve canal (IANC) at the right and left side and in males and females. Material and Methods Cone-beam computed tomography scans of 34 individuals were analyzed at four sites, that is, mesiobuccal section of the mandibular first and second molar and distobuccal section of first and second molar at both right and left sides and bone thickness as well as the bone depth of buccal shelf and IANC was measured and compared between right and left side and in between males and females. Results Bone thickness increased progressively in the distal direction. The highest bone depth was recorded in the distobuccal section of the second molar. IANC was also mapped and the result showed that the bone height from the cementoenamel junction (CEJ) to IANC decreased posteriorly but the bone depth was &gt;18 mm at all sites. Very few parameters showed statistically significant differences between the right and left sides. Bone height to IANC from CEJ showed statistically significant differences between genders at a few sites with male subjects having higher values. Bone thickness in the IANC region showed no gender dimorphism. Conclusion The appropriate site for mandibular buccal shelf mini-implant placement is the distobuccal region of the mandibular second molar.

A<sc>BSTRACT</sc>Background:The continuous evolution in orthodontics introduces innovative materials and methods to enhance treatment efficacy. Among these advancements, orthodontic anchorage screws, particularly miniscrews, have revolutionized treatments by offering diverse nonsurgical solutions for managing space discrepancies and certain skeletal malocclusions. The success of miniscrews is influenced by various factors including patient-related factors (age, sex, skeletal pattern, and oral hygiene), miniscrew-related factors (diameter, length, shape), and treatment-related factors (technique, applied forces, and insertion site).Materials and Methods:This study used Cone Beam Computed Tomography (CBCT) to evaluate the mandibular buccal shelf area for miniscrew placement across different sagittal and vertical skeletal patterns in 63 subjects, categorized based on the ANB angle and Jarabak ratio into Class I, II, III, and horizontal, average, and vertical growth patterns, respectively. Measurements were taken at specific sites related to the mandibular first and second molars, focusing on angulation, buccal bone depth (4mm and 6mm from the cementoenamel junction), and buccal bone thickness (6mm and 11mm from the cementoenamel junction).Results:There were no significant statistical differences in any measurement between the right and left hemiarches. The values for the bone around the distal root of the mandibular second molar were significantly greater than the other values. With regard to Sagittal Skeletal Pattern, Class I cases showed greater values as compared to Class II and Class III with a significant difference in the angulation, bone depth, and thickness at 11 mm from CEJ. Although values tended to be greater in patients with horizontal growth pattern, the difference was not statistically significant.Conclusion:Mandibular buccal shelf provides an optimal bone site for miniscrew insertion with better osseous characteristics at the distal root of the mandibular second molar. Subjects with skeletal Class I and horizontal growth pattern exhibit the most favorable osseous characteristics in the MBS area. However, in terms of bone thickness at 6 mm from CEJ Class III cases showed significant difference compared to Class I and Class II.

Medial sigmoid depression (MSD) is an anatomical variation located just below the deepest point of the sigmoid notch (SN). The etiology of MSD is unknown. It has been reported that increased maximum bite force affects the occurrence of MSD, and vertical growth pattern affects SN morphology. The aim of this study was to investigate the effects of these malocclusions on the presence and morphology of MSD and SN, since bite force can change with vertical and sagittal growth patterns. This is the first study to investigate the effects of vertical growth pattern on the presence and morphology of MSD, and the effects of sagittal growth pattern on SN morphology. Panoramic and lateral cephalometric radiographs of a total of 634 (427 female, 207 male) patients aged from 18 to 35 years (mean 19.58) were included in this retrospective study. MSD and SN shapes, SN depth and width were evaluated on panoramic radiographs. Mann Whitney-U, Kruskal-Wallis and Chi-square tests were used for data analysis. Sagittal and vertical growth patterns were not significantly associated with the presence and shape of MSD (p&gt;0.05). SN depth was greater in individuals with class III malocclusion, and both SN depth and width were lower in hyperdivergent individuals. There was no significant relationship between SN shapes and vertical and sagittal growth patterns (p&gt;0.05). SN depth is affected by both vertical and sagittal growth pattern, and SN width is affected only by vertical growth pattern. The presence of MSD was not associated with growth pattern.

Localization of mandibular canal by buccal object rule

ObjectivesTo assess the validity of the vertical tube-shift method using intraoral periapical radiography (IOPAR) for determining the relationship between the mandibular third molar roots and the inferior alveolar nerve (IAN) canal in comparison with cone-beam computed tomography (CBCT).Materials and MethodsFifty impacted mandibular third molars were analyzed using the IOPAR vertical tube-shift method and CBCT. The relationship of the IAN canal to the impacted mandibular third molar was recorded as buccal, lingual or in line with the apex and was compared with CBCT findings. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the vertical tube-shift method in depicting the relationship (buccal/lingual/in line with the apex) of the IAN canal to the third molar root apex was calculated.ResultsThe sensitivity and specificity PPV and NPV of the IOPAR vertical tube-shift technique was found to be highest for a lingual relationship (100%) followed by buccal (94.4%, 92.3%, 97.1%, and 85.7%) and in line with the apex relationship (88.9%, 95.0%, 80.0%, and 97.4%) of the IAN canal with the third molar root apex, respectively. A statistically significant association was observed between the IOPAR vertical tube-shift method and the CBCT with a P-value <0.01.ConclusionThe vertical tube-shift method can be used as an effective diagnostic tool in assessing the relationship of the IAN canal to the third molar root apex with high sensitivity, specificity, PPV, and NPV.

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To evaluate the position of the root apices of posterior teeth of mandible with inferior alveolar nerve canal and the cortical bone on cone beam computed tomography. The retrospective study was conducted from September to October 2021 at the Aga Khan University Hospital, and comprised cone beam computed tomography scans between November 2017 and October 2021 scans of healthy individuals of either gender aged 18-71 years with healthy, untreated, mandibular posterior teeth bilaterally. Shortest distance from apices of the mandibular posterior teeth to the border of inferior alveolar nerve canal, and to the mandibular buccal cortex were measured on the scans. Data was analysed using SPSS 23. Of the 106 scans, 55(52%) were males and 51(48%) were females. Of the 746 33teeth in the scans, 385(51.6%) were present in the scans of males and 361(48.4%) in those of the females. For all mandibular posterior teeth, the distances in females were shorter than males, but for the distance from root apices to the IAN canal, the difference between genders was significant for the roots of second premolar and second molar only on the left side (p≤0.05). Regarding the distance from the root apices to the buccal cortex, no significant difference was found between the genders, for each type of tooth, (p>0.05). Correlations between the distance from apex to inferior alveolar nerve (r<0.30) and between age and apex to buccal cortex distance (r<0.28) were weak. Procedures planned apical to second premolar and second molar teeth can potentially damage the inferior alveolar nerve.

The mandibular buccal shelf area is an extra-alveolar anchorage site that has high quality and quantity of bone, provides biomechanical benefits and has low failure rates. It is essential to place the implant in the region of bone with optimal thickness. The aim of this study was to determine the suitable site of the mandibular buccal shelf for bone screw insertion at 90 degrees and 30 degrees angles of insertion and various heights, angulations, areas of the buccal shelf in prognathic and retrognathic mandibles, and vertical and horizontal growth patterns. In this retrospective study, we evaluated the cone-beam computed tomography (CBCT) images of 48 patients in the age range of 18-30 years, divided into four groups. Seven sectional sites were examined at 3, 5, and 7 mm from the alveolar crest at 90 degrees and 30 degrees. The angulation and area of the buccal shelf were examined. Cortical bone thickness increased distally from the first to the second molar in all four groups. The preferred site for buccal shelf implant placement was distal to the mandibular second molar. The maximum amount of cortical bone was observed distal to the second molar, 7 mm vertically from the alveolar crest, when the buccal shelf implant was placed at 30 degrees angulation to the long axis of the tooth.

This study aimed to investigate the association between skeletal malocclusions and dental maturity in aGerman population. Aretrospective cross-sectional study was conducted with 542 patients (274 males, 268 females) aged 6-16years from Germany. Skeletal sagittal malocclusions were classified as classI,II, orIII according to the ANB, and vertical growth patterns of the mandible were determined using the Articulare-Gonion-Menton angle. Dental maturity was estimated using the Demirjian method on panoramic radiographs, and the deviation between dental age and chronological age (delta) was calculated. Among the sample, 43.9% presented skeletal classI, 41.5% classII, and 14.6% classIII malocclusions. In our study population, mandibular vertical growth patterns were distributed as 53.5% normodivergent, 43.4% hyperdivergent (vertical), and 3.1% hypodivergent (horizontal). The mean chronological age was 11.6 years, while the mean dental age was 11.7years, with an average delta of 0.08 (standard deviation = 1.2) years. No significant correlations were found between dental age deviation and the chosen cephalometric variables (p > 0.05). No significant associations were found between dental age deviation and sagittal and vertical malocclusions (p > 0.05). Skeletal malocclusions were not associated with deviations in dental maturity in this German sample. These findings indicate that dental development occurs independently of skeletal discrepancies, supporting the reliability of the Demirjian method across clinical and research contexts.