Dry Human Skulls Research Articles

Biomechanical behavior of adhesive cement layer and periodontal tissues on the restored teeth with zirconia RBFDPs using three-kinds of framework design: 3D FEA study

PurposeTo investigate stress and strain concentrations on resin-bonded fixed dental prostheses (RBFDPs) frameworks of different design using finite element analysis. MethodsA human dry skull was scanned and models were produced using three-dimensional printer. After abutment preparation, three frameworks, including a three-unit RBFDP, and two-unit cantilevered RBFDPs using #21 and #23 for the abutment tooth, were fabricated. Scanned data were subtracted to define boundary of each structure. Occlusal force (200N) was loaded at 45° to long axis of the pontic. The distributions of shear stress and principal strain in the RBFDP models were measured to evaluate the risk for framework-debonding from the abutment teeth and the impact on periodontal tissue. ResultsThe percentage voxels with shear stress >11MPa in adhesive cement layer of three-unit RBFDP using #21 and #23 were 4.16% and 2.25%, respectively; in two-unit cantilevered RBFDPs, it was 19.25% using #21, and 23.4% using #23. The maximum principal strain on periodontal ligaments in two-unit cantilevered RBFDPs using #21 was the largest, and smallest in the three-unit RBFDP. The maximum principal strain in framework was largest in the two-unit cantilevered RBFDP using #23, and smallest in the three-unit RBFDP. ConclusionsThe risk for framework-debonding in three-unit RBFDPs was substantially lower than that in two-unit RBFDPs. In difficult cases with indication for three-unit RBFDPs, two-unit cantilever design using the canine would be more advantageous for preservation of periodontal tissue, while for risk of framework-debonding, the design using the central incisor would be more advantageous.

The Morphological Grading and Comparison of Sutural Patency Among Cranial Sutures in Dry Human Skulls.

To investigate the degree of fusion (patency) among cranial sutures in human dry skulls in the Anatolia. One-hundred fifty-eight human dry skulls that were accepted as adults according to the teeth eruption were macroscopically examined and photographed with Canon 400B (55 mm objective). The grades of fusion of coronal, sagittal, and lambdoid were quantitatively analyzed by using the modified grading scale. According to the extent of patency, the sutures were graded as grade-0 (open), grade-1 (fused but not obliterated), grade-2 (50%< obliterated), grade-3 (50% > obliterated), and grade-4 (100% obliterated). The authors determined and compared the rate for each grade of sutural patency on coronal, sagittal, and lambdoid sutures. The cranial sutures of 4 cranii (4/158; 2.53%) had grade-4 fusion, whereas there were no any cranii with sutures of grade-0 fusion. The number of each grade of fusion among cranial sutures of 158 skulls, in descending order, was as follows: 171 (grade-3), 145 (grade-1), 133 (grade-2), and 25 (grade-4). The grade-4 fusion was significantly less observed than the others. The grade-1 and grade-4 fusion of lambdoid sutures were established as the most (66/41.8%) and least (5/3.2%) common fusions among cranial sutures, respectively. The frequencies of each grade of fusion for each cranial suture were determined in a descending order: coronal (grade-3 > 2 > 1 > 4), sagittal (grade-3 > 2 > 1 > 4), and lambdoid sutures (grade-1 > 3 > 2 > 4). The frequency of grade-1 fusion of lambdoid suture (66/41.8%) was significantly different when compared with coronal (39/24.7%) and sagittal sutures (40/25.3%), respectively. The grades of fusion (or sutural patency) vary among cranial sutures.

Complete Type of Metopism in Adult Human Dry Skull – Anatomical Variation

Complete Type of Metopism in Adult Human Dry Skull – Anatomical Variation

Strain Distribution and Amount of Force Required During Pterygomaxillary Dysjunction: A Comparison of Pterygoid Versus Shark-fin Osteotome.

This study was conducted to compare the efficacy of Obwegeser's pterygoid osteotome and Laster shark-fin osteotome by measurement of strain adjacent to the pterygomaxillary suture and the amount of force required for dysjunction. Two popular instruments Obwegesser's pterygoid and shark-fin osteotome were tested on dry human skulls. The external force required for separation of the pterygomaxillary suture with these osteotomes was generated by an electronically controlled 'Instron' tester Bi-06-108. Tests were performed with pterygoid osteotome placed on one randomly chosen side and shark-fin osteotome on the other side of the same specimen. The amount of strain developed by each of these instruments was recorded using two strain gauges on the right and left lateral pterygoid plates. [Table: see text]. Based on the distribution of strain, from this study, we conclude that Laster shark-fin osteotome is efficacious over Obwegeser's Pterygoid osteotome, in Le fort I osteotomy.

EVALUATION OF INCISIVE FOSSA DIMENSIONS ON HUMAN DRY SKULLS BY OCCLUSAL RADIOGRAPHS AND CONE-BEAM COMPUTED TOMOGRAPHY

To analyze the average dimensions of the incisive fossa and the frequency of cystic lesions at the nasopalatine region on human dry skulls, by occlusal radiographs and cone beam computed tomography (CBCT).

Accuracy and Reproducibility of Radiographic Images for Assessing Crestal Bone Height of Implants Using the Precision Implant X-ray Locator (PIXRL) Device.

Assessment of crestal bone levels around implants is essential to monitor success and health. This is best accomplished with intraoral radiographs exposed at 90 degrees to the long axis of the implant, but this can be challenging to achieve clinically. Radiographic paralleling devices produce orthogonal radiographs but traditionally have required access to the implant body for each exposure. This study was conducted to determine if use of the Precision Implant X-ray Locator (PIXRL), a radiographic paralleling device that indexes the implant at the time of surgical placement, can produce orthogonal radiographs of dental implants more accurately than traditional radiologic techniques for assessing crestal bone levels. Three dental implants were inserted in dry human skulls in supracrestal positions to simulate crestal bone loss (maxillary right first premolar [site 14], maxillary right central incisor [site 11], and mandibular left second premolar [site 35]). The implants were masked with a soft tissue moulage and restored with provisional restorations. Four dental assistants exposed six radiographs using their usual and customary technique and six using the PIXRL device for each implant. A single examiner measured crestal bone levels on the radiographs relative to the implant platform shoulder on the mesial and distal of each implant. Recorded measurements were compared to the known values. Statistical analysis was completed using a generalized linear regression model to analyze the differences, and post-hoc comparisons with pairwise adjustment were applied. The images produced using the PIXRL device were more accurate overall compared to traditional techniques and were also more consistent. The greater degree of accuracy was statistically significant for all sites with the exception of the mesial measurements of the implant at site 11. This study demonstrates that the use of the PIXRL device can assist clinicians in obtaining more accurate orthogonal radiographs for assessing crestal bone height and would be a useful tool for researchers utilizing radiographic imaging of implants as a longitudinal measure of implant success and stability.

Morphometric Analysis of Foramen Magnum in Adult Dry Skulls in Dakshina Kannada

The objectives of the present study were to determine the type and morphometric measurements of Foramen magnum (FM) in dry human skulls of Dakshina Kannada district of Southern India. Material and Methods: The present study included 50 adult human skulls of which 32 were males and 18 females. The type of foramen magnum observed macroscopically. Antero-posterior (APD) and transverse diameters (TD) were measured by using stainless steel electronic digital callipers. Foramen magnum Index (FMI) was calculated by using formula FMI = APD/TD. Results: Present study observed 4 types of shapes of foramen magnum, among them ovoid type was found higher frequency (48%). Antero-posterior diameter is a distance between Basion and Opisthion 34.95 mm in males and 34.58 mm in females out of 34.81 mm. The transverse diameters 28.66 mm in males and 28.84 mm in females out of 28.73 mm. Foramen magnum index ≥ 1.2 was considered as ovoid and found in 56% of skulls. Conclusion: We believe that the present study provided additional information about the morphology and morphometric analysis of foramen magnum which is important to radiological, and neurosurgical literature.

Influence of CT parameters on STL model accuracy

PurposeAdditive manufactured (AM) skull models are increasingly used to plan complex surgical cases and design custom implants. The accuracy of such constructs depends on the standard tessellation language (STL) model, which is commonly obtained from computed tomography (CT) data. The aims of this study were to assess the image quality and the accuracy of STL models acquired using different CT scanners and acquisition parameters.Design/methodology/approachImages of three dry human skulls were acquired using two multi-detector row computed tomography (MDCT) scanners, a dual energy computed tomography (DECT) scanner and one cone beam computed tomography (CBCT) scanner. Different scanning protocols were used on each scanner. All images were ranked according to their image quality and converted into STL models. The STL models were compared to gold standard models.FindingsImage quality differed between the MDCT, DECT and CBCT scanners. Images acquired using low-dose MDCT protocols were preferred over images acquired using routine protocols. All CT-based STL models demonstrated non-uniform geometrical deviations of up to +0.9 mm. The largest deviations were observed in CBCT-derived STL models.Practical implicationsWhile patient-specific AM constructs can be fabricated with great accuracy using AM technologies, their design is more challenging because it is dictated by the correctness of the STL model. Inaccurate STL models can lead to ill-fitting implants that can cause complications after surgery.Originality/valueThis paper suggests that CT imaging technologies and their acquisition parameters affect the accuracy of medical AM constructs.

Technical note: Intra-alveolar morphology assessed in empty dental sockets of teeth missing post-mortem

Dental human identification relies on distinctive traits detected and compared between ante-mortem (AM) and post-mortem (PM) data. Several distinctive traits may be found in dental roots, such as dilacerations and bifurcations. However, teeth are often dislodged during the manipulation of skeletal remains, charred bodies and bodies retrieved from water. In these situations the identification process is hampered. The present study aims to retrieve information of teeth missing PM through the investigation of intra-alveolar morphology in empty dental sockets using different dental impression materials. This study was conducted using a dry human skull and 6 techniques for intra-alveolar impression, namely: (1) alginate using a dental tray; (2) heavy-body condensation silicone (HBCS) using manual compression; (3) HBSC using a blunt tip probe; (4) HBCS using a dental tray; (5) light- and HBCS using a syringe and a dental tray; and (6) polyether using a syringe and a dental tray. These techniques were evaluated based on 5 criteria: (I) intra-alveolar flow; (II) registration of apical morphology; (III) tensile strength; (IV) complexity; and (V) cost. The best outcomes considering the cost and benefit relation of each technique were observed in the following order: techniques #3>#2>#5>#6. Techniques #1 and #4 did not reach satisfactory outcomes for application in the forensic routine. Forensic dentists must be aware of the possibility of retrieving PM dental information even in the absence of teeth. The impression of intra-alveolar morphology may contribute significantly as source of PM dental information for human identifications.

FORENSIC STUDY FOR DETERMINATION OF THE INCIDENCE OF PERSISTENT METOPIC (FRONTAL) SUTURE AND ITS RELATION TO AGE AND SEX AMONG SAMPLE OF EGYPTIAN SKULLS

Introduction: At birth the frontal bone contains two portions, separated by the metopic (frontal) suture. Metopism is the condition of having a persistent metopic suture. Aim of the present study was to determine the incidence of persistence of metopic suture, their shape and its relation to age and sex in Egyptian human skulls. Material and Method: The study was conducted on 147 human dry skulls which belong to the museum of the department of Anatomy, Faculty of Medicine, Menoufia University. The metopic sutures were classified as complete and incomplete types. Incomplete metopic sutures were divided into three groups as present in the lower part of the frontal bone, in the upper part and in the middle part. The incomplete lower metopic sutures were further subdivided into linear, ‘V’ shaped and ‘U’ shaped. Results: From this study, absence metopic sutures were observed in 84 (57.1%) skulls, while it was present in 63 (42.9%) ones. The complete metopic suture (metopism) was seen in 12 (8.2%) skulls and incomplete one in 51 (34.7%). Among the incomplete ones, linear, ‘U’ and ‘V’ shaped was found in 36 (24.5%), 9 (6.1%), and 6 (4.1%), respectively. All incomplete metopic sutures were found in the lower part of frontal bone, but no suture remnant was found in the upper and middle part of frontal bone. Incomplete lower V shaped metopic suture presented in all female skulls. There were statistical significant relation between absent, complete, incomplete lower linear and incomplete lower V shaped metopic suture regarding age. Also there was statistical significant relation between metopism regarding age and sex. There was sensitivity and specificity for both age and sex with metopic suture. Conclusion and recommendation: The incidence of metopism was 8.2% while incomplete metopic sutures were 34.7%. This incidence may be valuable information for identification of the person and for radiologists and neurosurgeons in practice to concern about metopic suture in emergency diagnosis of frontal bone fractures.

Extensiometric analysis of strain in craniofacial bones during implant-supported palatal expansion.

Palatal expansion has several orthodontic and orthopedic applications, such as increasing maxillary transverse dimensions and correcting maxillary atresia, oral breathing, and skeletal cross-bites. Little is known about the strain to which craniofacial bones are submitted when a palatal expander is loaded. The objectives of the present work were to propose a new palatal bone-borne titanium device (expansion screw), to determine patterns of strain distribution in craniofacial bones during palatal expansion and to show the clinical results of a new palatal expander supported by implants. For in vitro testing, the palatal expander supported by two commercially pure titanium (cp Ti) implants was inserted parallel to the median palatine suture of four dry adult human skulls. Uniaxial and triaxial strain gauges were attached to craniofacial bones and connected to a signal acquisition system. An expansion screw was turned and strain data were collected during palatal expansion. The results showed that the bone strain distribution in craniofacial bones loaded by the palatal bone-borne titanium device was complex: the strain was tensile in the palatine cortical bone and compressive in pterygopalatine processes, nasal bones, and orbital floor. The maximum compressive strain occurs in the upper portion of the pterygopalatine processes and the strain changes from compressive to tensile in the zygomatic process. The experimental results suggest that the bone strain due to the palatal expander is distributed over all craniofacial bones and that the upper portions of pterygopalatine processes are the main sites of resistance to palatal expansion. The new palatal expander supported by two cp Ti implants proposed was employed on adult patient as an illustrative report, where adequate palatal expansion was achieved. The new protocol proposed was less invasive, risky, painful and costless for the correction of moderate maxillary transverse deficiency.

Incidence, number and laterality of epipteric bones in the pterion in dry human skulls of south india

Incidence, number and laterality of epipteric bones in the pterion in dry human skulls of south india

Effect of changing the head position on accuracy of transverse measurements of the maxillofacial region made on cone beam computed tomography and conventional posterior-anterior cephalograms.

This study aimed to assess the effect of head position on the accuracy of transverse measurements of the maxillofacial region on CBCT and conventional posteroanterior (PA) cephalograms. The second objective of this study was to find skull positions with the greatest and smallest effect on transverse measurements in the maxillofacial region. PA cephalograms and CBCT scans were obtained from 10 dry human skulls in 7 positions, namely the central position, 10° and 20° rotations, 10° and 20° tilts and 10° and 20° tips. The CBCT scans were converted to PA cephalograms on which distances from six landmarks, namely the nasal cavity, zygomatic arch, jugale, antegonion, condylion and zygomaticofrontal suture to the mid-sagittal plane, were measured on both sides using Dolphin two-dimensional software. The paired t-test was used to compare the mean values separately in each position (for each landmark) with the gold standard (central skull position). The interclass correlation coefficient and the Bland-Altman plot were used to compare the mean values measured by two observers. The mean values of the distances measured on CBCT PA cephalograms were greater than those measured on conventional PA cephalograms; this difference was statistically significant for some landmarks (p < 0.005). The rotated position (as compared with the central position) caused the greatest change in values for most landmarks on both sides (p < 0.005). The CBCT PA cephalogram was more accurate than the conventional PA cephalogram, and landmarks farther from the midline exhibited greater changes on cephalograms compared with those closer to the midline. Patients are at risk of improper positioning when undergoing extraoral radiography such as PA cephalograms. Changes in head position may affect the transverse measurements and thus the treatment plan.

Morphometric analysis of occipital condyle in human adult dry south indian skulls

Morphometric analysis of occipital condyle in human adult dry south indian skulls

Accuracy of linear measurements around dental implants by means of cone beam computed tomography with different exposure parameters.

The aim of this study was to determine the accuracy of linear measurements around dental implants when using CBCT unit devices presenting different exposure parameters. Dental implants (n = 18) were installed in the maxilla of human dry skulls, and images were obtained using two CBCT devices: G1-Care Stream 9300 (70 kVp, 6.3 mA, voxel size 0.18 mm, field of view 8 × 8 cm; Carestream Health, Rochester, NY) and G2-R100 Veraview® (75 kVp, 7.0 mA, voxel size 0.125 mm, field of view 8 × 8 cm; J Morita, Irvine, CA). Measurements of bone thickness were performed at three points located (A) in the most apical portion of the implant, (B) 5 mm above the apical point and (C) in the implant platform. Afterwards, values were compared with real measurements obtained by an optical microscopy [control group (CG)]. Data were statistically analyzed with the significance level of p ≤ 0.05. There was no statistical difference for the mean values of bone thickness on Point A (CG: 4.85 ± 2.25 mm, G1: 4.19 ± 1.68 mm, G2: 4.15 ± 1.75 mm), Point B (CG: 1.50 ± 0.84 mm, G1: 1.61 ± 1.27 mm; G2: 1.68 ± 0.82 mm) and Point C (CG: 1.78 ± 1.33 mm, G1: 1.80 ± 1.09 mm; G2: 1.64 ± 1.11 mm). G1 and G2 differed in bone thickness by approximately 0.76 mm for Point A, 0.36 mm for Point B and 0.08 mm for Point C. A lower intraclass variability was identified for CG (Point A = 0.20 ± 0.25; Point B = 0.15 ± 0.20; Point C = 0.06 ± 0.05 mm) in comparison with G1 (Point A = 0.56 ± 0.52; Point B = 0.48 ± 0.50; Point C = 0.47 ± 0.56 mm) and G2 (Point A = 0.57 ± 0.51; Point B = 0.46 ± 0.46; Point C = 0.36 ± 0.31 mm). CBCT devices showed acceptable accuracy for linear measurements around dental implants, despite the exposure parameters used.

Evaluation of the diagnostic efficacy of two cone beam computed tomography protocols in reliably detecting the location of the inferior alveolar nerve canal.

Reliable three-dimensional localization of the inferior alveolar nerve canal (IANC) is valuable for a variety of dentoalveolar procedures. Although conventional CBCT offers three-dimensional information at a reasonably low dose, it is still a significant amount of radiation. In this ex vivo study, we evaluated the ability of a 180° rotational CBCT acquisition protocol with lower number of basis projections to create a CBCT data set for reliable localization of the IANC compared with a conventional 360° rotational CBCT acquisition. 50 dry human skulls were imaged using 180° and 360° rotational CBCT protocols. Measurements of the IANC throughout its course in the mandible were carried out. Two raters evaluated the measurements and rated the scans based on their ability to visualize the IANC, and the measurements were carried out. The IANC length measurements for the 180° and 360° protocols were identical. There was no difference between evaluations by the two raters for the two protocols. Interexaminer reliability values were >90% for the two protocols. The sensitivity values for the two protocols were >95%. The specificity for both protocols was 100%. 180° CBCT acquisition protocol is able to accurately locate the IANC with high reliability and is comparable to a conventional 360° protocol.

Elongated Styloid Process: A Morphometric Study, with Radiological Evaluation in Dry Human Skulls, with its Clinical Implications

Elongated Styloid Process: A Morphometric Study, with Radiological Evaluation in Dry Human Skulls, with its Clinical Implications

Effectiveness of digital subtraction radiography in detecting artificially created osteophytes and erosions in the temporomandibular joint.

PurposeErosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ.Materials and MethodsFive intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods.ResultsThe area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes.ConclusionThe accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.

Sutural Morphology of the Types of Asterion: A Study on Dry Human Skulls

Sutural Morphology of the Types of Asterion: A Study on Dry Human Skulls

Morphometric study of foramen magnum in human dry skulls

Morphometric study of foramen magnum in human dry skulls