Stress Propagation in the Craniofacial Skeleton on Frontal Impact-A Virtual Simulation Study.

Background: The research paper emphasizes on virtual simulation of craniofacial skeleton to understand its Biomechanics. Methods: In this study, a 3D finite element model of the skull was created using CT scan data. All complexities of the skull geometry are simulated using ABAQUS software. The model was validated and then, subjected to frontal impact. Energy plots for the same were obtained. Impact analysis was done, and weak areas susceptible to fracture and hence, failure are identified. Results & Discussion: One of the emerging areas of applications of computational bio-mechanics is to understand the behavior of the skull during a traumatic injury, such as head impact during accidents. Finite element study is one such part where significant amount of research is being carried out to understand and predict the craniofacial injuries. For the head and brain trauma analysis, there are many software packages available, including ANSYS, LS-DYNA and ABAQUS. Research is being carried out towards developing high-fidelity human models, especially of the human skull to understand the bio-mechanical behavior when subjected to external impact. Impact analysis done in our study showed that a small change in impact velocity can result in a large change in damage that can happen. Conclusion: The study is expected to complement the existing treatment methodologies. Further, appropriate knowledge of fracture biomechanics can be used to design and develop safety measures in automobiles, sport guards, helmets to prevent and reduce facial injuries.

An Analysis of the Stress induced in the Periodontal Ligament during Extrusion and Rotation Movements- Part II: A Comparison of Linear vs Nonlinear FEM Study.

BACKGROUND: Optimal orthodontic forces are those which stimulate tooth movement with minimal biological trauma to the tooth, periodontal ligament (PDL) during and alveolar bone. Among various types of tooth movements, extrusion and rotational movements are seen to be associated with the least amount of root resorption and have not been studied in detail. The mechanical behavior of the PDL is known to be nonlinear elastic and thus a nonlinear simulation of the PDL provides precision to the calculated stress values. Therefore in this study, the stress patterns in the PDL were evaluated with extrusion and rotational movements using the nonlinear finite element method (FEM). MATERIALS AND METHODS: A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modelling software. Stresses in the PDL were evaluated with extrusive and rotational movements by a 3D FEM using ANSYS software with nonlinear material properties. RESULTS: It was observed that with the application of extrusive load, the tensile stresses were seen at the apex whereas the compressive stress was distributed at the cervical margin. With the application of rotational movements, maximum compressive stress was distributed at the apex and cervical third whereas the tensile stress was distributed on cervical third of the PDL on the lingual surface. CONCLUSION: For rotational and extrusion movements, stress values over the periodontal ligament was within the range of optimal stress value as proposed by Lee, with a given force system by Proffit as optimum forces for orthodontic tooth movement using nonlinear properties. During rotation there are stresses concentrated at the apex, hence due to the concentration of the compressive forces at the apex a clinician must avoid placing heavy stresses during tooth movement.

An Analysis of the Stress Induced in the Periodontal Ligament during Extrusion and Rotation Movements: A Finite Element Method Linear Study Part I.

BACKGROUND: Orthodontic tooth movement occurs due to various biomechanical changes in the periodontium. Forces within the optimal range yield maximum tooth movement with minimum deleterious effects. Among various types of tooth movements, extrusion and rotational movements are seen to be associated with the least amount of root resorption and have not been studied in detail. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with extrusion and rotational movements using the finite element method FEM. MATERIALS AND METHODS: A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with extrusive and rotational movements by a 3D FEM using ANSYS software with linear material properties. RESULTS: It was observed that with the application of extrusive load, the tensile stresses were seen at the apex, whereas the compressive stress was distributed at the cervical margin. With the application of rotational movements, maximum compressive stress was distributed at the apex and cervical third, whereas the tensile stress was distributed on cervical third of the PDL on the lingual surface. CONCLUSION: For extrusive movements, stress values over the periodontal ligament was within the range of optimal stress value as proposed by Lee, with a given force system by Profitt as optimum forces for orthodontic tooth movement using linear properties. During rotation there are stresses concentrated at the apex, hence due to the concentration of the compressive forces at the apex a clinician must avoid placing heavy stresses during tooth movement.

Anxiety and Depression in Facial Injuries: A Comparative Study.

BACKGROUND: This study was performed to identify the presence of anxiety and depression in patients who had sustained facial injuries; additionally we aimed to identify other variables that may modify the psychological response to trauma that include gender and age. MATERIALS AND METHODS: The participants were 153 patients from multimodal trauma centers in Bangalore city who sustained disfiguring facial injuries were taken up. Of the 153 patients, 81 patients were male (51 less than 50 years of age and 30 more than 50 years of age) and 72 patients were female (40 less than 50 years of age and 32 more than 50 years of age) and 111 patients with non-disfiguring facial injuries out of which 54 were male patients and 57 were female patients. The assessments were carried out at 3 time intervals (the date of discharge [DOD], 1-month post-operatively and 6 months post-operatively) of the follow-up. The hospital anxiety and depression scale (HADS) was used to assess the anxiety and depression of the facial trauma patients. RESULTS: Statistically significant higher means of HADS both for anxiety and depression were present in patients with disfiguring facial injuries compared to non-disfiguring facial injuries, female patients compared to male patients after the 1-month and 6 months post-operatively, the mean anxiety and depression scores of males and female patients were significantly higher for those who aged less than 50 years compared to those who aged more than 50 years. CONCLUSION: The results of this study led to the conclusion that in comparison with patients who had facial disfiguring injuries and non-disfiguring facial injuries, the mean HADS scores were significantly higher in the disfiguring facial injury patient. This indicates increased Anxiety and Depression levels and this was observed at all three study intervals (DOD, 1-month and 6 months post-operatively). The HADS was higher in female patients who were lesser than 50 years age compared to male patients of the same age group, which implies higher anxiety and depression levels.

Stress Induced in Periodontal Ligament under Orthodontic Loading (Part II): A Comparison of Linear Versus Non-Linear Fem Study.

BACKGROUND: Simulation of periodontal ligament (PDL) using non-linear finite element method (FEM) analysis gives better insight into understanding of the biology of tooth movement. The stresses in the PDL were evaluated for intrusion and lingual root torque using non-linear properties. MATERIALS AND METHODS: A three-dimensional (3D) FEM model of the maxillary incisors was generated using Solidworks modeling software. Stresses in the PDL were evaluated for intrusive and lingual root torque movements by 3D FEM using ANSYS software. These stresses were compared with linear and non-linear analyses. RESULTS: For intrusive and lingual root torque movements, distribution of stress over the PDL was within the range of optimal stress value as proposed by Lee, but was exceeding the force system given by Proffit as optimum forces for orthodontic tooth movement with linear properties. When same force load was applied in non-linear analysis, stresses were more compared to linear analysis and were beyond the optimal stress range as proposed by Lee for both intrusive and lingual root torque. To get the same stress as linear analysis, iterations were done using non-linear properties and the force level was reduced. CONCLUSION: This shows that the force level required for non-linear analysis is lesser than that of linear analysis.

Stress Induced in the Periodontal Ligament under Orthodontic Loading (Part I): A Finite Element Method Study Using Linear Analysis.

BACKGROUND: Orthodontic tooth movement is a complex procedure that occurs due to various biomechanical changes in the periodontium. Optimal orthodontic forces yield maximum tooth movement whereas if the forces fall beyond the optimal threshold it can cause deleterious effects. Among various types of tooth movements intrusion and lingual root torque are associated with causing root resoprtion, especially with the incisors. Therefore in this study, the stress patterns in the periodontal ligament (PDL) were evaluated with intrusion and lingual root torque using finite element method (FEM). MATERIALS AND METHODS: A three-dimensional (3D) FEM model of the maxillary incisors was generated using SOLIDWORKS modeling software. Stresses in the PDL were evaluated with intrusive and lingual root torque movements by a 3D FEM using ANSYS software using linear stress analysis. RESULTS: It was observed that with the application of intrusive load compressive stresses were distributed at the apex whereas tensile stress was seen at the cervical margin. With the application of lingual root torque maximum compressive stress was distributed at the apex and tensile stress was distributed throughout the PDL. CONCLUSION: For intrusive and lingual root torque movements stress values over the PDL was within the range of optimal stress value as proposed by Lee, with a given force system by Proffit as optimum forces for orthodontic tooth movement using linear properties.

Traumatic impact loading on human maxillary incisor: A Dynamic finite element analysis.

BACKGROUND: The most vulnerable tooth is the maxillary incisor, which sustains 80% of dental injuries. Dynamic Finite element analysis is used to understand the biomechanics of fracture of maxillary incisor under traumatic impact loading. AIM: The aim was to investigate the stress patterns of an upper incisor in a three-dimensional (3D) model under traumatic impact loading in various directions. MATERIALS AND METHODS: A 3D finite element model of the upper incisor and surrounding tissues was established. A sinusoidal force of 800N was applied over a period of 4 ms. RESULTS: Software performs a series of calculations and mathematical equations and yields the simulation results. During the horizontal impact (F1), stresses were concentrated in the cervical area of the crown, reaching peak stress of 125 MPa at 2 ms. CONCLUSION: A horizontal force exerted on the labial surface of the tooth tends to cause cervical crown fractures, oblique crown root fractures, and oblique root fractures.

Post-traumatic Stress Disorder in Facial Injuries: A Comparative Study.

AIM: The aim of the study was to identify the presence of post-traumatic stress disorder (PTSD) in patients who had sustained facial injuries, additionally, we aimed to identify other variables that may modify the psychological response to trauma that include gender, age and presence of disfigurement post-treatment and visible scars/orthopedic injuries. MATERIALS AND METHODS: Participants comprised of 460 patients from several multinodal trauma centers in Bengaluru City, Karnataka, who had sustained facial injuries that had healed either with or without significant disfigurement or scarring and with visible/orthopedic injuries. One hundred and eleven patients of the chosen 460 had sustained nondisfiguring facial injuries while 153 patients sustained disfiguring facial injuries, 64 patients who sustained facial injury (i.e. 19.5%) were lost to follow-up and were not included in the study. One hundred and thirty-two had sustained orthopedic/visible injuries; however, in this group, 18 (i.e. 13.6%) patients were lost to follow-up and were excluded from the study. The impact of events scale (IES) was used to check the presence of PTSD. RESULTS: Statistically significant higher means of IES were present in patients with disfiguring facial injuries compared to nondisfiguring facial injuries, female patients compared to male patients, patients with disfiguring facial injuries compared to orthopedic/visible injuries and patients who were younger than 50 years of age compared to patients who were older than 50 years of age and the results observed were similar at all three study intervals (date of discharge (DOD), 1 month and 6 months postoperatively). CONCLUSION: Patients with disfiguring facial injuries had significantly higher PTSD levels compared to patients with nondisfiguring facial injuries, patients with orthopedic/visible injuries had statistically significant lower IES scores which could not be strictly termed PTSD when compared to patients with disfiguring facial injuries who had high scores of IES corresponding to high levels of PTSD and these results were observed at all three study intervals (DOD, 1 and 6 months postoperatively). Female patients with disfiguring facial injuries had significantly higher PTSD levels compared to male patients (at all the study intervals) and patients younger than 50 years of age had significantly higher PTSD levels compared to older patients.

A Comparative Study of Post-traumatic Stress Disorder, Anxiety, Depression and Change in Sexual Functioning of Patients with Facial Injuries and Patients with Extremity Injuries.

BACKGROUND: This study was performed to identify and compare the presence of and the levels of post-traumatic stress disorder (PTSD), anxiety, depression and if any change in sexual functioning is present in patients with disfiguring facial injuries, nondisfiguring facial injuries and visible extremity injuries. MATERIALS AND METHODS: A total of 378 patients from multi modal trauma centers in Bengaluru city were included for the study. A total of 153 patients were those who had disfiguring facial injuries, 111 patients with nondisfiguring facial injuries and 114 patients had sustained a visible extremity injury that was not covered by clothing (disfigurement /scarring). The assessments were carried out at three time intervals (the date of discharge, 1 month postoperatively and 6 months postoperatively) of the follow-up. The impact of events scale (IES), the hospital anxiety and depression scale (HADS) and changes in sexual functioning questionnaire (CSFQ) were used. RESULTS: Statistically significant higher means of IES, HADS (both for anxiety and depression) were present in patients with disfiguring facial injuries compared to patients with nondisfiguring facial injuries and visible extremity injuries and this was present at all three study intervals (date of discharge,1 st postoperative month and 6th postoperative month). There was a statistically significant change in the means of CSFQ scores of visible extremity injuries compared to other groups at the date of discharge bordering on sexual dysfunction, there was a raise in CSFQ scores among all three groups at the 1st postoperative month and the 6th postoperative month which was above the dysfunction cut-off. CONCLUSION: The results of this study led to the conclusion that in comparison with patients who had sustained disfiguring facial injuries, nondisfiguring facial injuries and visible extremity/ orthopedic injuries, the mean IES scores, HADS scores for both anxiety and depression of the facial disfiguring injury patients was higher at all three study intervals (date of discharge,1st postoperative month and 6 months postoperatively), indicating higher PTSD levels, anxiety and depression in patients with disfiguring facial injuries, CSFQ scores were above the cutoff suggested at the 1st month and 6th month postoperative indicating no sexual dysfunction in all the three groups.

Validation of a Kannada version of the Impact of Events Scale (IES).

BACKGROUND: This study presents a Kannada translation and validation of the Impact of Event Scale in a population of men and women exposed to maxillofacial trauma and orthopedic/ general trauma. MATERIALS & METHODS: A total of 96 study subjects from multi modal trauma centers in Bangalore city completed the Kannada translated questionnaire at the time of discharge, the first post- operative month and the sixth month of follow up. RESULTS: The Kannada IES is reliable when analyzed with the students T-test, it has good internal consistency with Cronbach's α-coefficients ranging from .970 to .974, the test-retest reliability with Karl Pearson's correlation of the scale at all three time intervals showed significant correlation. A principal component analysis was conducted to ascertain the validity and two components were derived from the 15 questions which were able to explain 88% of the variation and the two were retained (intrusion and avoidance). CONCLUSION: The Kannada version of the IES has satisfactory reliability, internal validity, test-retest reliability and the factor structure was similar to the proposed theoretical structure of the IES. How to cite this article: Tavane PN, Raghuveer HP, Kumar RD, Shobha ES, Rangan V, Dutt CS. Validation of a Kannada version of the Impact of Events Scale (IES). J Int Oral Health 2013; 5(5):38-47.

An experimental study of arch perimeter and arch width increase with mandibular expansion: a finite element method.

AIMS: The objective of this study was to estimate the increase in arch perimeter associated with mandibular lateral expansion, To estimate the increase in intermolar width with mandibular lateral expansion and to find out the changes of tooth inclination with mandibular expansion. MATERIALS AND METHODS: The mandibular bone with dentition of indian skeletal specimen was obtained. The computer tomogram (CT) slices of the mandible were taken. Finite element model (FEM): Numerical representation of the geometry was created by dividing the geometry into finite number of elements and the elements were connected together with nodes at the junction. RESULTS: The result of the study showed when 10° of lateral expansion was applied to the lower buccal segment at the center of rotation found at 4.3 mm below the root apex of first molar, a space of 1.3 mm between the canine and first premolar, and thus an increase in arch perimeter of 2.6 mm. CONCLUSION: The tip of the mesiolingual cusp of the first molar moved 4.2 mm laterally, resulting in a change in intermolar width by 8.4 mm. Three-dimensional simulation showed that 1 mm of intermolar expansion increased the arch perimeter by 0.30 mm. CLINICAL SIGNIFICANCE: As the finite element method evolves and scientists are able to more clearly define physical properties of biological tissues, more accurate information can be generated at the level that other analytical methods cannot fully provide data.This result would be of value clinically for prediction of the effects of mandibular expansion.

Gorham's massive osteolysis of the mandible - a progressive radiographic presentation.

Massive osteolysis is well known under the synonyms Gorham's disease, vanishing bone disease and phantom bone disease. It is a rare condition of unknown aetiology and results in the progressive destruction of bony structures. Only a few cases have been reported in the jaws. Considering the rarity of the condition, we report here an interesting and unique case of massive osteolysis of the lower jaw that initially affected the mandibular basal and alveolar bone, and subsequently involved the rami and the condyles. The clinical and radiological findings were consistent with the criteria for the diagnosis of Gorham's massive osteolysis.

Solitary, central neurofibroma of the mandible: a case report.

A case of Solitary Central Neurofibroma in a 53 years old female is reported. This is an apparently single primary lesion, in which physical and Radiological examination failed to reveal other bony lesions or the stigmata of multiple neurofribomatosis.