Exploratory Study of Growth of Circumference of Mandibular Fossa Adjacent to Petrous Portion of Temporal Bone Using Dried Skulls

The morphogenetic process of development of the circumference of the mandibular fossa during tooth eruption, which involves the replacement of deciduous teeth with permanent teeth, is strongly affected by occlusion. To the best of our knowledge, no studies have investigated the effect of occlusion on this process. This study investigated the morphogenetic process of development during tooth eruption using dried skulls harvested from Indian donors. The average distance between the ala-major-squamosa suture and the foramen ovale according to age group was as follows: 3.24 mm in the 8-month-old group and 8.92 mm in the adult group. The average distance between the ala-major-squamosa suture and the apex of the articular tubercle according to age groups was as follows: 10.38 mm in the 8-month-old group and 19.34 mm in the adult group. The average distance between the point of intersection of the petrosquamous fissure and petrotympanic fissure located on the perpendicular line drawn posteriorly from the shortest distance of the medio-lateral axis between the ala-major-squamosa suture and the apex of the articular tubercle according to age group was as follows: 9.68 mm in the 8-month-old group and 14.3 mm in the adult group. These results suggest that the mandibular fossa is strongly affected by load due to occlusion, unlike the growth of the neurocranium. This indicates that the effect of occlusion is a secondary element in the morphogenetic process of development of the circumference of the mandibular fossa.

Assessing the Articular Eminence Asymmetry in Dentate, Partially Edentulous and Edentulous patients Using Cone-Beam Ct

Background and Objectives:

The relationship between the articular eminence (AE) inclination and masticatory system in the biomechanics of temporomandibular joint (TMJ) is defined by the degree with normal values of 30°–60° obtained between the posterior wall of the AE and a horizontal reference plane. The purpose of this study was to assess the asymmetry of the AE in dentate, partially edentulous, and edentulous patients using cone-beam computed tomography (CBCT) imaging and to compare the determined asymmetry in the dentulous with partially and completely edentulous patients.

Materials and Methods:

CBCT images of 120 TMJ joints in sixty patients were evaluated. AE inclination and height values were traced on the central sagittal slice of right and left TMJ. The patients were grouped as dentate, partially edentulous, and edentulous with an age range of 20–80 years. Statistical analysis included student's paired and independent t-test, analysis of variance, and Tukey's post hoc test, and P < 0.05 was considered statistically significant.

Results:

AE inclination revealed highest value in dentate patients (60.98 ± 5.42) followed by partially edentulous (53.40 ± 7.91) and lowest in the edentulous patients (51.43 ± 3.63). P < 0.001 was statistically significant between these groups.

Conclusion:

The results obtained in the present study showed steep inclination of AE in dentate followed by partially edentulous and edentulous subjects. No significant differences among the age, gender, and sides were found.

Verification of mechanical load generated by functional orthodontic appliances

Functional appliances are widely used for promoting mandibular growth by utilizing a construction bite position. We aimed to measure the mechanical load generated by movement of functional appliances and determine the factors influencing this load. Thirteen patients aged 8-12 years were selected for the study, and the load was measured using a previously developed measurement device. To investigate the factors affecting the load, the temporomandibular joint morphology and muscles related to the mandible were examined using cone-beam computed tomography. The standard regression coefficients of the factors affecting the load per millimeter of movement distance were 0.64 and 0.66 for (a) the inclination of the articular eminence and (b) the angle between occlusal plane and posterior temporalis, respectively. Measurement of the occlusal plane to the posterior temporalis and the inclination of the articular eminence were significantly different (p < 0.05). The angle of inclination of the articular eminence emerged as a strong influencing factor. Similarly, the influence of measurements from the occlusal plane to the posterior temporalis was considerable since the posterior temporalis muscle is the most active when the mandible is extended forward. We also found a possible relationship between the occlusal force and load at the construction bite position. To our knowledge, this is the first study to determine the actual load associated with the angle of the temporalis muscle to the occlusal plane, inclination angle of the articular eminence, angle between the occlusal plane and the Frankfort plane, and the angle between the geniohyoid muscle and the occlusal plane. Therefore, mechanical considerations need to be more accurate to facilitate safe orthodontic treatment.

Cone-beam Computed Tomographic Evaluation of the Anatomical Changes of Temporomandibular Joint Use of Pre-post Dentures: A Time-control Study

AIM AND OBJECTIVE

The growth of the temporomandibular joint (TMJ) gets affected by multiple factors like aging, occlusion state, and by the movement of the jaw while masticating and swallowing. Radiographic imaging is often utilized as a vital diagnostic adjunct in the evaluation of certain examinations of the TMJ.

MATERIALS AND METHODS

In this in vivo study, 30 male participants with mean age 55 years, having edentulous maxillary and mandibular arches from the Outpatient Department of Prosthodontics, were randomly selected. Group I (n = 30) patients who were edentulous for the last 4-5 years but without wearing dentures. Whereas group II (n = 30) patients who were edentulous for the last 4-5 years but were wearing dentures for this period. Maxillary and mandibular dentures were fabricated and delivered to subjects. Subjects were subjected to the TMJ analysis with the help of CBCT. Radiological images of dentomaxillofacial structures were analyzed by a specialist with a dual monitor inside a darkened silent room. On the monitor, three times measurements were recorded followed by calculation of mean value. The recordings were taken on both sides and thus, 210 sites were analyzed altogether, followed by the statistical analysis using SPSS software version 15.0.

RESULTS

The mean ages of group I and II were 59.00 ± 6.74 and 58.27 ± 6.75 years, respectively. The intra- and intergroup comparisons were done using a one-sample t-test. Differences in mean intercondylar width in groups I and II were not found to be statistically significant. The difference in mean length of glenoid fossa was not statistically significant at any of the above observation periods. A continuous decline in mean length of glenoid fossa was observed with time in both groups. The range of change in articular eminence length was found to be statistically significant for both the groups (p < 0.05).

CONCLUSION

This study shows that the articular eminence flattening is correlated with age; on the other hand, the rate of deformation was found significantly more in total edentulous subjects as compared to subjects having normally maintained occlusion. The anatomical changes inside the TMJ have been much greater expressed within the completely edentulous subjects in whom the angle of sagittal condyle path declines and so does the articular eminence height.

CLINICAL SIGNIFICANCE

It is essential to provide the edentulous patient with early prosthetic and occlusal rehabilitation after extractions to prevent the anatomical changes in TMJ.

MRI investigation of TMJ disc and articular eminence morphology in patients with disc displacement

PURPOSE

The aim of this study was to evaluate the morphology of the temporomandibular joint (TMJ) articular eminence and disc and the relationship between morphology and inclination in patients with disc displacement.

METHODS

TMJ magnetic resonance images (MRI) of 30 patients with disc displacement with reduction (DDWR) on one side and disc displacement without reduction (DDWOR) on the other side were analyzed. Articular eminence morphology was subdivided as box, sigmoid, flattened and deformed. Articular disc configuration was characterized as biconcave, biplanar, biconvex, hemiconvex and folded. The articular eminence inclination was measured as the angle between the Frankfurt plane and a line drawn from the glenoid fossa roof to the lowest point of the articular eminence.

RESULTS

Regarding articular eminence shape, in both DDWR and DDWOR groups, the most frequent articular eminence shape was flattened shape. Regarding to the disc morphology, biplanar shape was the most frequently observed in both DDWR side and DDWOR side. The mean articular eminence inclination was 32.62 and 33.85 in the DDWR and DDWOR side, respectively.

CONCLUSIONS

Disc and articular eminence morphology was found to have no relationship with TMJ internal derangement except the relationship between flattened type and internal derangement. The articular eminence inclination have no influence on disc reduction.

Evaluation of structural skeletal asymmetry of the glenoid fossa in adult patients with unilateral posterior crossbite using surface-to-surface matching on CBCT images

OBJECTIVES

To compare, using surface-to-surface (StS) matching, any shape differences between the crossbite and noncrossbite side of the glenoid fossa and articular eminence in adult patients affected by posterior unilateral crossbite (PUXB) and compare them with unaffected controls.

MATERIALS AND METHODS

32 cone beam computed tomography (CBCT) scans of patients (mean age: 23.72 ± 3.74 years) undergoing surgical maxillary expansion were analyzed to obtain three-dimensional models of the left and right glenoid fossae that were superimposed using stable anatomical reference points and then compared using StS matching to evaluate the presence of any shape differences. These findings were compared with those obtained from 16 CBCT scans of unaffected controls (mean age: 23.72 ± 3.73 years).

RESULTS

A mean difference of >11% was found between the study group and controls when comparing the matching percentages of the two sides of the glenoid fossa and articular eminence at all three levels of tolerance selected for this study. These differences were found to be highly statistically significant (P ≤ .0001).

CONCLUSIONS

According to the shape analysis findings, adult PUXB patients exhibit a higher degree of glenoid fossa and articular eminence shape differences compared to unaffected controls.

Flattening of the articular eminence is associated with the loss of occlusal support: radiological study

BACKGROUND

Degenerative changes in the temporomandibular joint might be associated with ageing and/or with the loss of occlusal support.

OBJECTIVE

The aim of the study was to evaluate whether the inclination of the posterior slope of the articular eminence changes in association with: (i) ageing in patients with maintained occlusal support zones (OSZs); and (ii) the loss of OSZs in elders.

METHODS

In this retrospective radiological study, selected orthopantomograms were allocated into the following groups: I-age 18-35, maintained OSZs, II-age 36-60, maintained OSZs, III-age >60, at least one OSZ per side maintained, IV-age >60, loss of all OSZs. The inclination of the articular eminence was measured relative to the Frankfort plane.

RESULTS

The mean values of the inclination of the slope of the articular eminence amounted 34.05° ± 5.17°, 36.68° ± 5.65°, 34.86° ± 6.26° and 26.31° ± 5.12° for group I, II, III and IV respectively. There were no significant differences between the groups I to III. Group IV differed significantly from each of the previous groups.

CONCLUSIONS

Flattening of the articular eminence is associated with the loss of OSZs rather than ageing.

Evaluation of pneumatic cavities surrounding temporomandibular joint by cone beam computed tomography

OBJECTIVE

The purpose of this study was to detect the prevalence and characteristics of pneumatization in the roof of the glenoid fossa (PRGF) and articular eminence (PAT) by using cone beam computed tomography (CBCT) images.

MATERIAL AND METHOD

CBCT images of 378 patients (756 TMJ) were analyzed to determine the PRGF and PAT. Twenty-eight patients were excluded due to some reasons such as trauma, degeneration, previous surgical operation of temporomandibular joint (TMJ). Pneumatization was detected in 297 of 350 patients, but not pneumatization in 53 patients. Age, gender, laterality (unilateral, bilateral) and lacunarity (unilacunar, multilacunar) were recorded. Unilateral types were also noted as right and left localization. Chi-square test was used to evaluate relationship between pneumatization and gender, lacunarity and laterality.

RESULTS

PRGF and/or PAT were diagnosed in 491 (70%) TMJ components whom 178 (51%) were male and 172 (49%) were female with mean age of 40.38±18.34 years. In total, 103 (35%) of the patients had unilateral and 194 (65%) patients had bilateral pneumatization.

CONCLUSION

CBCT provides reliable and precise images to detect pneumatization surrounding TMJ structure in comparison to 2D images. Evaluation of TMJ components accurately before surgical intervention is crucial to prevent complication or increase the success of therapy.

Spatial analysis of mandibular condyles in patients with temporomandibular disorders and normal controls using cone beam computed tomography

OBJECTIVES

The aim of the study is to investigate the condylar position and its relation to articular eminence and axial condylar angle in temporomandibular joint disorder (TMD) patients and in normal controls using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

CBCT temporomandibular joint (TMJ) images of 70 participants (38 males and 32 females, mean age 26.4 years) were analyzed. They were divided into control group (including 35 subjects) and study group (including 35 subjects). Linear measurements of joint space and condyle determined the condylar position of each TMJ. Articular eminence height and inclination were also measured with axial condylar angle to determine its relation to condylar position. Independent and paired sample t-test was applied to compare between the groups and TMJ sides of the same group at significance level of 0.05.

RESULTS

Statistical significant differences were found between males and females of both groups regarding superior joint space (SJS), lateral joint space, A-P, and M-L condyle distance (P < 0.05). SJS, medial joint space (MJS), and eminence angle were greater (P < 0.01) in male's joints with TMD with flatter axial condylar angle (P < 0.05), when compared with normal TMJ counterpart. Females TMJs showed significantly higher values of MJS of affected side when compared with normal counterpart with flatter axial condylar angle (P < 0.05).

CONCLUSION

Superior and MJS parameters were the ones that showed significant differences between affected and nonaffected joints. The mean axial condylar angle was smaller in joints with abnormal TMJ. This indicates that the condyles of the affected joints may rotate inward.

Prevalence of pneumatization of the articular eminence and glenoid fossa viewed on cone-beam computed tomography examinations in a Turkish sample

OBJECTIVE

The aim of this study is to evaluate the prevalence of the pneumatization of the articular eminence and glenoid fossa (PAT and PGF, respectively) using cone-beam computed tomography (CBCT).

METHODS

CBCT images of 1000 patients (511 females and 489 males) representing 2000 regions of interest (the glenoid fossa and articular eminence of each patient) were examined retrospectively with regard to age, gender, laterality, and type of pneumatization. The mean age of the female patients was 39.66 and that of males was 39.79. Suitable images from patients aged 16 years and over found in the archives of CBCT images were included in the study. The data were assessed using IBM SPSS 20 and statistical comparisons between two categorical variables were conducted using Chi square tests.

RESULTS

It was observed that 14.7% of the patients had PAT and 47.1% had PGF. There was no significant difference in PAT and PGF prevalence between ages, age ranges, and gender in our study (p > 0.5).

CONCLUSIONS

It is important to evaluate the pneumatic cells in the articular eminence and glenoid fossa regions before surgery. It was also found that CBCT is more helpful in detecting pneumatization than plain film.

Prevalence and characteristics of pneumatizations of the articular eminence and roof of the glenoid fossa on cone-beam computed tomography

OBJECTIVE

The aim of this study was to determine the prevalence and characteristics of pneumatization of the articular tubercle (PAT) and pneumatization of the roof of the glenoid fossa (PRGF) in a large population using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

This study was designed to evaluate the CBCT images of 1000 patients. The prevalences of the pneumatizations by age, sex, locularity, and laterality were determined. The significance of differences between variables was evaluated by the Chi-square test and analysis of variance.

RESULTS

PAT was detected in 28.4% of the zygomatic bone sides and PRGF in 29.6%. Bilateral PAT was detected in 176 (17.6%) patients and bilateral PRGF in 195 (19.5%). The mean age of patients with PAT was 47.33 years and that of patients with PRGF was 45.62 years. Multilocular appearance was observed significantly more often than unilocular type for both pneumatizations (p < 0.01). Unilateral PAT cases were slightly, but significantly, higher than bilateral PAT cases (p = 0.047), while no significant difference was observed between unilateral and bilateral PRGF cases.

CONCLUSIONS

In conclusion, PAT and PRGF can be assessed more accurately on CBCT images than on plain radiographs. During routine radiological investigations, maxillofacial radiologists should be aware of zygomatic air cells.

Do we need a high resolution computed tomography-based novel risk classification for eminectomy?

INTRODUCTION

Besides mastoid air filled cells, pneumatizations (PN) occasionally occur in the articular eminence (AE) of the temporomandibular joint (TMJ). These findings represent no pathological character but may increase the risk of perforating the AE during eminectomy with potential harming the skull base. Various classifications catagorize the degree of temporal PN without focussing solely on the AE. Panoramic radiograph (PR) and computed tomographie (CT) are both described as suitable for diagnosing PNs. Are the common ways of imaging capable for precise diagnosis and do we need a risk pattern for eminectomy?

METHODS

A 4-year retrospective study evaluated high resolution computed tomographie (HRCTs) of 300 patients. We screened digitalized skull images for PN of the AE. The frankfort horizontal was determined as the reference mark for measurements. Images were assessed by a craniomaxillofacial surgeon and a radiologist.

RESULTS

300 patients (600 AEs) were investigated. We detected 60 PNs (10% of all AEs) in 44 patients (14.7%). We subdevided the findings according to the extent of PN. 10 AEs showed PNs of less than 20% (type 1); n=18: 21-40% (type 2); n=18: 41-70% (type 3). n=14: 71 to 100% (type 4). In 32 cases (72.7%) with 42 PNs a PR existed. Of the 42 AEs, corresponding PN could be detected in 21 cases (50%).

DISCUSSION

PNs are a potential threat when performing TMJ surgery. Sufficient preoperative imaging is required to avoid severe endangerment for the patient. CT imaging is most suitable detecting PNs. PR seem to fail in diagnosing PNs of different degree. Our novel HRCT-based classification shows the distribution of PNs and provides a risk pattern.

CONCLUSION

HRCT exceeds the diagnostic accuracy of PR in detecting pneumatized AEs. PR is not capable for detecting PNs of different degree. A novel classification may increase the prediction of perforation risk. Restricting eminectomy to reduce height only to a certain amount reduces the risk of complications.

Prevalence and Characteristics of Articular Eminence Pneumatization: A Cone-Beam Computed Tomographic Study

Purpose

The temporal bone represents a variety of pneumatization patterns with clinical significance for planning surgical procedures in this area. The purpose of the present study was to assess the prevalence and characteristics of the glenoid fossa and articular eminence pneumatization and to classify the pattern of pneumatization using CBCT images.

Methods

CBCT images of 327 patients (654 temporal bones) were evaluated to determine pneumatized articular eminence prevalence and characteristics. Gender, age, laterality, type and grade of pneumatization were recorded for the left and right sides. Chi-square test was used to evaluate the relationship between pneumatized articular tubercle and gender, grade and type.

Results

PAT was identified in 251 (76.7%) patients of whom 139 (55.4%) were male and 112 (44.6%) were female with a mean age of 30.31 ± 10.32 years. Bilateral PAT occurred in 175 (69.7%) patients. Three hundred and ninety-six (93%) of areas were multilacunar, and 30 (7%) were unilacunar. Of 654 areas, 228 (34.8%) had grade 0, 299 (45.7%), grade 1, 92 (14.1%), grade 2 and 35 (5.4%), grade 3. No statistically significant correlation was found between prevalence of pneumatization, gender, type and grade.

Conclusion

The present study emphasized the need to assess PAT before surgical intervention of TMJ. CBCT provides reliable and accurate information to determine the characteristics, the exact extension of pneumatization and its relationship to the adjacent structures. The preoperative temporal bone CBCT is a crucial component of the evaluation of PAT in patients candidate for surgical intervention of TMJ.

An in vitro study to evaluate the accuracy of orthopantomograph as an aid to determine condylar guidance

PURPOSE

The study was conducted to evaluate the accuracy of orthopantomograph (OPG) as an aid to determine condylar guidance.

METHODOLOGY

The condylar guidance was measured using the impressions of glenoid fossae and radiographs (OPG) on thirty dried human skulls. Frankfurt horizontal plane (FHP) was used as a reference plane in both the methods and wire markers were adapted to make the contours of glenoid fossae discernible for both the methods. The condylar inclination angle was measured between FHP and a line joining the most concave point on the glenoid fossa with the most inferior point on the articular eminence on both right and left sides.

RESULTS

Pearson correlation was used for statistical analysis, and it showed a strong correlation between anatomic and radiographic methods (r = 0.864 for the left side, r = 0.873 for the right side) as well as between right and left sides (r = 0.830). The data were also subjected to regression analysis (linear and panel estimation approach) which showed that OPG could be effectively used to predict the condylar guidance (r2 = 0.6160).

CONCLUSION

Although OPG shows a higher value than anatomic method, it can be used as an aid to set condylar guidance on semi-adjustable articulator.

ZACD: A Retrograde Panoramic Analysis among Indian Population with New System of Classification

INTRODUCTION

Zygomatic Air Cell Defect (ZACD) has been considered as a normal radiographic variant with a spare knowledge. This should be judged before any surgical procedure of the temporal region as lack of which can lead to infections of cranium and may other complications.

AIM

The present study was undertaken to estimate the prevalence and characteristics of ZACD and to propose a classification for the same using digital panoramic radiography.

MATERIALS AND METHODS

A total of 6825 digital panoramic radiographs were evaluated retrospectively of subjects aged between 4-90 years from both genders. The radiographs were evaluated by 4 (four) oral radiologists and the ZACD was recorded only when the decision was indisputable.

RESULTS

Out of 6825 digital panoramic radiographs evaluated ZACD was noticed in 133 subjects with an overall prevalence of 1.94%. A male predilection was noted in the present study with the maximum prevalence during the second, third and fourth decade of life and as the age increases its prevalence decreases. Most commonly it was found to be unilateral and the unilocular presentation being more common.

CONCLUSION

Most of the finding of the present study is in acceptance with those conducted previously, but some of the finding contradicts those in the previous ones. It can be because of low sample size of the previous studies. Moreover this study gives a new system to classify these defects to help diagnose the nature of the defect.

A clinico-radiographic analysis of sagittal condylar guidance determined by protrusive interocclusal registration and panoramic radiographic images in humans

PURPOSE

To evaluate the correlation between sagittal condylar guidance obtained by protrusive interocclusal records and panoramic radiograph tracing methods in human dentulous subjects.

MATERIALS AND METHODS

The sagittal condylar guidance was determined in 75 dentulous subjects by protrusive interocclusal records using Aluwax through a face bow transfer (HANAU™ Spring Bow, Whip Mix Corporation, USA) to a semi-adjustable articulator (HANAU™ Wide-Vue Articulator, Whip Mix Corporation, USA). In the same subjects, the sagittal outline of the articular eminence and glenoid fossa was traced in panoramic radiographs. The sagittal condylar path inclination was constructed by joining the heights of curvature in the glenoid fossa and the corresponding articular eminence. This was then related to the constructed Frankfurt's horizontal plane to determine the radiographic angle of sagittal condylar guidance.

RESULTS

A strong positive correlation existed between right and left condylar guidance by the protrusive interocclusal method (P 0.000) and similarly by the radiographic method (P 0.013). The mean difference between the condylar guidance obtained using both methods were 1.97° for the right side and 3.18° for the left side. This difference between the values by the two methods was found to be highly significant for the right (P 0.003) and left side (P 0.000), respectively. The sagittal condylar guidance obtained from both methods showed a significant positive correlation on right (P 0.000) and left side (P 0.015), respectively.

CONCLUSION

Panoramic radiographic tracings of the sagittal condylar path guidance may be made relative to the Frankfurt's horizontal reference plane and the resulting condylar guidance angles used to set the condylar guide settings of semi-adjustable articulators.