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Showing 8 results for Mandible
An evaluation on time status of functional orthopedic treatment in class II skeletal patients with cervical vertebrae maturation stage (CVMS) index
Z. Dalili , A. Miandog ,
Volume 17, Issue 3 (8-2004)
Abstract

Statement of Problem: Considerable response to functional orthopedic appliances treatment in class II skeletal patients occurs during pubertal growth spurt. Therefore, it seems necessary to investigate indices indicating mandibular growth pattern. It has been proved that analyzing cervical vertebral maturation stage is a more valid index than that of hand wrist.

Purpose: The aim of this study was to evaluate the time status of functional orthopedic treatment in class II skeletal patients using CVMS index.

Materials and Methods: In this descriptive-inferential study, lateral cephalometric radiographs of 153 class II skeletal patients with mandibular deficiency, before treatment, were studied by an oral and maxillofacial radiologist using the index of cervical vertebral maturation stage (CVMS) and were categorized in three phases: CVMS I (desirable phase of treatment), CVMS II (ideal phase), and CVMS III (undesirable phase of treatment).

Results: Statistical analysis ranked the prevalence of treatment phases as: 41.8% in desirable phase (CVMS I), 28.1% in ideal phase (CVMA II) and 30% in undesirable phase (CVMS III). No significant differences were found between the three phases using Chi-square analysis. Time status of functional orthopedic treatment was also evaluated based on age and sex. The results showed significant differences between two sexes (P=0.032).

Conclusion: The present study suggests the analysis of CVMS index, along with clinical criteria, in the determination of an ideal time for functional orthopedic treatment to prevent patients’ exhaustion during treatment Period.


Pre-implant linear tomography using film-screen and Photostimulable Phosphor Plate in mandible
M. Panjnoush , M. Mirzaey , M. Tari ,
Volume 23, Issue 2 (10-2010)
Abstract

Background and Aims: Radiographic examination prior to implant placement is often complemented with tomography for location of vital anatomic structures and evaluation of bone volume. The aim of this study was to evaluate the accuracy of Photostimulable Phosphor Plate system with that of conventional film-screen in mandibular pre-implant linear tomography

Materials and Methods: In this test evaluation study, tomograms of 2 dry human mandibles were taken using the both film-screen and Photostimulable Phosphor Plate. 10 sites were selected in each mandible and marked with gutta-percha. Distance of superior border to the mandibular canal and the total height and width of mandible were measured on the tomograms and also on the mandibles after sectioning. The radiographic values were compared with real ones.

Results: After correction of tomographic values by the magnification factor of the unit, the mean of absolute differences with reality in linear tomography using film-screen and Photostimulable Phosphor Plate for height of mandible were 0.59mm (SD=0.54) and 0.65mm (SD=0.72), respectively. The mean of absolute differences with reality in linear tomography using film-screen and Photostimulable Phosphor Plate for width of mandible were 0.34mm (SD=0.33) and 0.31mm (SD=0.33), respectively. In localization of the mandibular canal, the mean of absolute differences with reality were 0.54mm (SD=0.30 ) and 0.52mm (SD=0.56) for linear tomography using film-screen and Photostimulable Phosphor Plate, respectively. In linear tomography using film-screen, 100% of measurements for localization of the canal, 80% of height and 95% of width were with in ± 1mm error limits. In linear tomography using Photostimulable Phosphor Plate, 75% of measurements for localization of the canal, 75% of height and 95% of width were within ± 1mm error limits. There was no significant difference between linear tomography using film-screen and Photostimulable Phosphor Plate in localizing the mandibular canal and height and width estimation (P>0.05).

Conclusion: The accuracy of linear tomography using film-screen and Photostimulable Phosphor Plate in height and width estimation and localization of the canal is within acceptable limits.


Effect of mandibular plane angle on image dimensions in linear tomography
H. Bashizadeh Fakhar, A. Abbaszadeh,
Volume 24, Issue 1 (3-2011)
Abstract

Background and Aims: Accurate bone measurements are essential for determining the optimal size and length of proposed implants. The radiologist should be aware of the head position effects on image dimensions in each imaging technique. The purpose of this study was to evaluate the effect of mandibular plane angle on image dimensions in linear tomography.
Materials and Methods: In this in vitro study, the vertical dimensions of linear tomograms taken from 3 dry mandibles in different posteroantenior or mediolateral tilts were compared with actual condition. In order to evaluate the effects of head position in linear tomography, 16 series of images while mandibular plane angle was tilted with 5, 10, 15 and 20 degrees in anterior, posterior, medial, or lateral angulations as well as a series of standard images without any tilt in mandibular position were taken. Vertical distances between the alveolar crest and the superior border of the inferior alveolar canal were measured in posterior mandible and the vertical distances between the alveolar crest and inferior rim were measured in anterior mandible in 12 sites of tomograms. Each bone was then sectioned through the places marked with a radiopaque object. The radiographic values were compared with the real conditions. Repeat measure ANOVA was used to analyze the data.
Results: The findings of this study showed that there was significant statistical difference between standard position and 15º posteroanterior tilt (P<0.001). Also there was significant statistical difference between standard position and 10º lateral tilt (P<0.008), 15º tilt (P<0.001), and 20º upward tilt (P<0.001). In standard mandibular position with no tilt, the mean exact error was the same in all regions (0.22±0.19 mm) except the premolar region which the mean exact error was calculated as 0.44±0.19 mm. The most mean exact error among various postroanterior tilts was seen in 20º lower tilt in the canine region (1±0.88 mm) and for various mediolateral tilts the most exact error was seen in the canine region in 20º upper tilt (2.9±2 mm).
Conclusion: The mean exact errors in various regions and various 5º to 20º posteroanterior and mediolateral mandibular tilts were in the range of acceptable values (≤1 mm) except for the canine region. However, this effect is more considerable in mediolateral tilt compared with posteroanterior tilt, posterior region compared with anterior region, and upper tilt compared with lower tilt.


Thermal numerical assessment of jawbone drilling factor during implantology
Adel Pirjamali Neisiani, Nima Jamshidi, Mohsen Saraf Bidabad, Navid Soltani,
Volume 28, Issue 4 (1-2016)
Abstract

Background and Aims: Optimization drilling parameters in order to temperature decrease during creation of hole in the bone is an interested issue. The aim of this study was to achieve optimum values of drilling parameters based on the creation of minimum temperature during jawbone drilling.

Materials and Methods: In this study two models of mandible and maxilla was created and teeth 2, 5 and 8 from maxilla and teeth 25, 28 and 31 from mandible were removed. The drilling operation was performed under different conditions on jawbone models using finite element analysis and the maximum temperatures were measured in adjacent of holes.

Results: Drill bit head angle of 70 degrees was created the lowest maximum temperature during drilling operation. The lowest maximum temperatures were observed in the drill bit rotational speed, drill bit feed rate and the force exerted on the drill bit equal to 200 rpm, 120 mm/min and 60 N, respectively. The use of irrigation can decrease the maximum bone temperature about 7ºC. The maximum temperature differences in various regions of mandible and maxilla were approximately about 1ºC.

Conclusion: Sharpness of drill bit head angle, reduction of drill bit rotational speed, increasing drill bit feed rate and exerted force on drill bit and also the use of irrigation played effective roles in temperature decrease during jawbone drilling. Drilling site did not have important effect on the temperature changes during jawbone drilling.


Central odontogenic fibroma of mandible: A case report
Samaneh Bayat, Shirin Sakhdari, Ali Mokhtar, Ali Lotfi, Mehdi Amiri Siavashani,
Volume 28, Issue 4 (1-2016)
Abstract

Background and Aims: Central odontogenic fibroma is a rare odontogenic neoplasm that originates from odontogenic ectomesenchyme. Most cases occur in the mandible and between the ages of 11 and 39 years. The neoplasm shows a definite female preponderance, with a ratio of 2.2:1 and has a very low recurrence rate. The aim of this article was to report a case of this rare lesion which was accidentaly found.

Case Report: A 11-year-old female, during her orthodontic treatment and without any complain and any sign or symptoms, performed a panoramic image for assessing the permanent teeth buds. In the panoramic view a unilocular radiolucent lesion with well-defined and corticated borders in the right mandibular body region was evident. The lesion was treated with simple excision. Simple type of central odontogenic fibroma histopathologic features was observed in the microscopic view.

Conclusion: Although the central odontogenic fibroma is a rare benign neoplasm, however, a careful evaluation of radiographic images is important for early detection of lesions because the patient may have no clinical symptoms such as swelling, pain and paresthesia.


Biomechanical comparison between pure Ti and Zr -2.5%Nb dental implants after implantation by finite element analysis (FEA)
Adel Pirjamalineisiani, Mohsen Sarafbidabad, Nima Jamshidi,
Volume 29, Issue 3 (10-2016)
Abstract

Background and Aims: Improving dental implantation conditions in order to reduce the failure is always desirable for researchers. The aim of this study was to compare two different materials of dental implants from the viewpoint of biomechanical effect after placement and loading in the mandible.

Materials and Methods: A 3D model of mandible was designed in the MIMICS 10.01 software. Then, by using the obtained model, the end part of the mandible was designed in CATIA V5 software and a drilling operation was performed on the cortical bone of mandible by finite element analysis simulation method in DEFORM-3D V6.1 software. Thereafter, the 3D model of created hole was extract from the drilled site and an ITI dental implant model designed in the CATIA V5 software, was placed in the hole. The space remained between the implant and cavity was considered as a newly-formed cortical bone in drilled site after 6 weeks of dental implant placement and the mechanical properties of newly-formed bone were entered to DEFORM-3D V6.1 software. Then, a load was applied on the top surfaces of two dental implant models with the materials titanium and zirconium-2.5% niobium.

Results: The emerged volume changes in newly formed cortical bone around Ti and Zr-2.5 Nb dental implants were measured 0.238 and 0.242 percent, respectively. Furthermore, micro-motion of Ti and Zr-2.5 Nb dental implants were measured 0.00514 and 0.00538 mm, respectively.

Conclusion: The results of this study showed that Ti dental implant created better conditions than Zr-2.5 Nb dental implant in the mandible.


A study on the association of mandible anatomy with age and gender in panoramic radiography of patients referred to Rafsanjan dental school clinic
Zahra Tafakhori, Ghazaleh Mostafazadeh, Mahmod Sheikh Fathollahi,
Volume 29, Issue 4 (1-2017)
Abstract

Background and Aims: The purpose of this study was to evaluate the relationship between the mandible anatomy with age and gender in panoramic radiography of patients.

Materials and Methods: In this descriptive-sectional study, 322 panoramic radiography of patients at the age of 25-55 years old were evaluated. The patients were devided in three groups of 25-34, 35-44, 45-55 years old and the radiomorphometric indexes in panoramic radiography of the patients were measured. The collecting data were analyzed using independent two-sample t-test, one-way anova and multiple linear regression using SPSS statistical software (version 18).

Results: The average of radiomorphometric indexes don’t show a meaningfull statistical defference between different age groups. The average of all angles higher in females than that of males and other measured indexes were higher in males than females. Also, the mandibular foramen moved forward with the increase of age.

Conclusion: Based on the result of this study which was done on limited numbers, it can be concluded that the measured radiomorphometric indexes in this study didn’t have a high accuracy to predict Age and Gender.


Frequency assessment of maxillofacial fractures in trauma patients admitted in maxillofacial surgery ward in Sina and Shariati hospitals’ in 2018 and 2019
Maryam Mohammadi Nodeh, Majid Beshkar, Mohammad Javad Kharazi Fard,
Volume 34, Issue 0 (5-2021)
Abstract

Background and Aims: Fractures of the facial bones and jawbones could cause functional problems along with social and cosmetic problems. Various factors (including road accidents, assault, falling from height, sport injuries, and getting hit by a hard object) could cause these fractures. Collecting and reporting accurate epidemiologic data regarding the facial fractures are major steps toward planning preventive measures. The aim of this study was to collect the epidemiologic data regarding maxillofacial fractures in two referral centers (Shariati and Sina hospitals) in the city of Tehran.
Materials and Methods: The study was a cross-sectional retrospective investigation. All the necessary data were collected from the patients’ files and analyzed using SPSS 25.
Results: The present study pursued data of 454 trauma admitted patients in oral and maxillofacial surgery wards of Shariati and Sina hospitals in 1397 and 1398. These data showed that a number of 374 patients of all patients were men and the other 80 were women. The ratio of male patients to female patients was 4.5:1. In 290 of cases (64%), the fractures occurred as combined fractures and in 164 cases (36%), the fractures occurred as single fracture. These fractures happened mostly in the mandibular bone and in mandibular body, and the least of these fractures happened in Orbit. This study showed that there was a significant relation (with 95% confidence level) between the mandibular body fractures and mandibular angle fractures. This study also showed that there was another significant relation (with 95% confidence level) between the mandibular angle fractures and LeFort 2 fractures. In addition, this study also showed (by using k2 exam) a relation between the etiology of trauma and the number of fractures.
Conclusion: This present study showed that the maxillofacial fractures happened mostly in men much more than women. If we put motorcycle accidents and car accidents in a group together called road accidents, the most common etiology of maxillofacial fractures is road accidents. The results showed that the most fractures happened in the age range of 15-25 year old.
 


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