فهرست مطالب بهنام میرزاکوچکی

Nowadays, the use of dental implants in people with osteoporosis is increasing. The consequences of osteoporosis can be important to the success of osteosynthesis devices, prosthetics and dental implants. Using bisphosphonates, which with impressing bone remodeling and decreasing bone catabolic activity lead to increase bone formation can be used as a solution to increase bone density in patients with osteoporosis, which normally osteoporosis is considered as a risk to the acceptance of dental implants by alveolar bone. This study examines the effect of different concentrations of bisphosphonates on bone remodeling. By improving bone remodeling model and taking into account the drug concentration effect on bone resorption, drug effect will be considered. For this purpose, 5, 10 and 20 mg of alendronate per implant and control sample are simulated for a period of 360 days. By comparing the results with control sample, with increasing the drug dose, decrease in bone stress, increase in bone density and thus increase in young's modulus was observed.

Computer aided education can compensate for some deficiencies and limitations of traditional education. The aim of this study was to evaluate the effect of e-learning, as an adjunctive method of traditional education, in the form of video clips and PowerPoint presentations on the skills of fabricating the wire components of removable orthodontic appliance in the preclinical course of dental students.
This prospective quasi-experimental study was performed on 40 eighth semester dental students who were taking the course practical orthodontics 1 in Tabriz School of Dentistry in 2012-13 academic year. Participants were selected through convenience sampling and randomly divided into two groups. The control group received traditional trainings including practical training of fabricating the wire components of removable orthodontic appliance, and the experimental group received the same plus e-learning. The skills in fabricating three major components of removable orthodontic appliance namely Z spring, Adams clasp and labial bow were evaluated using a 21-item checklist. Data were analyzed by means of independent and paired t-tests.
The mean scores of the control and the experimental groups were 14.2±1.4 and 15.5±1.8 (out of 20) respectively and their difference was statistically significant (P=0.026, t=2.31). The mean score of labial bow fabrication was higher in the experimental group than that of the control group (p=0.01, t=2.72). However, the mean scores of Z spring and Adams clasp fabrication were not significantly different in the two groups.
Using E-learning as an adjunctive method of traditional education can improve the practical skills of fabricating the wire components of removable orthodontic appliances.

Periodontal ligament (PDL) is a soft fibrous tissue which is located between tooth and alveolar bone. Because the tissue is softer than the surrounding tissue, tooth movement is forced to follow the movement of the soft tissue. The goal of this study is comparison of periodentium related to single and two root teeth behavior with applying different loads. The modeling of the real 3D geometry of incisor and premolar periodentium is carried out using micro CT scan. PDL is considered as hyperelastic material and stress-strain distribution was investigated by applying different loads. The results of finite element simulation show that tooth displacement with different loading is not necessarily in direction of loading and also stress distribution show that PDL absorbs the stresses, consequently alveolar carry less stresses. Strain distribution in PDL and alveolar bone stress represents uniform distribution of force in two root tooth. The analogy of results shows the accommodation with pervious studies.

Orthodontic specialists interest in study of tooth movement mechanic, such as the relationship between applied force and the rate of tooth movement in orthodontic treatment. It is because of the complexity and variety of factors that can affect orthodontic treatment. The friction force at the contact surfaces with an undetermined magnitude, makes the orthodontic treatment unpredictable. In this study, friction coefficient and forces were investigated in new designed bracket that had beveled edge which has been modeled based on standard bracket. Torque, tip and angulations angles of the brackets slot are designed. Arch wires were modeled by two rectangular and circular cross-sections and the effect of geometry on the stress distribution and the friction force was investigated using Finite Element Method (FEM). The results have showed that the stress concentration generated in the bracket which has been the most curvature, decreased compared to the standard bracket at the contact wire and bracket braces. In addition, results have showed that friction in the beveled edge bracket was significantly decline compared to the standard bracket and also are less than the type with minor curvature. Results of investigation of friction between the two types of round and square wire, have revealed that the round wire has lower friction and confirmed previous studies. Finally, due to the reduced friction in the brackets which have been the most curvature, this type of design is appropriate to decrease friction force.

Cleft lip (CL) and cleft palate (CP) are among the most common congenital anomalies. Constituting 65% of head and neck anomalies in isolated or syndromic forms, they are considered as the most common head and neck congenital deformities in children. 15 children from the Tabriz Children Hospital were evaluated in this descriptive-analytic cross sectional study that possessed unilateral and bilateral cleft lip and palate with inclusion criteria. The effect of nasal floor reconstruction on the size of alveolar cleft and palatal anterior fistula formation were evaluated in primary unilateral and bilateral cleft palate. There were 11 (73.3%) male and only 4 (26.7%) female patients in the sample group. The mean duration from first consult to reconstructive surgery was 3.4±1.8 months (1 to 9 months range). The width of alveolar cleft and alveolar ridge angle on cleft side compared to normal side in sagittal and coronal axis was significant after nasal floor reconstruction (P=0.001, P=0.02), while septal angle changes were not significant (P=0.26), which means no increase in septal deviation has been documented. Considering the significant changes of alveolar cleft width and alveolar ridge angle on cleft side compared to normal side in sagittal and coronal axis after nasal floor closure, this method can be applied as a new interventional surgery in primary unilateral and bilateral cleft palate.