مجله تحقیق در علوم دندانپزشکی
سال چهارم شماره 2 (پیاپی 12، تابستان 1386)

in anthropology, one way to find the relations between communities and races, is evaluation of prevalence rate of the structural and genetic traits in each communities and races. The goal of this study was to determine the prevalence rate of carabelli trait in the maxillary first molar and it’s relation in the dental branch of Islamic Azad University as a source of in formations in the anthropological study. this discriptive study was carried out on the study cast of 360 sample (180 mal, 180 female) based on random sampling for each person we prepared a data sheet and at last we evalvated the prevalence rate of this trait with this data. Result with respect to the relative factors (sex) was evaluated. The result was classified in two main group of present and absence and four subgroup of unilateral, bilateral, developed, non developed. Data were analyzed using chi-square. 66.9% of evaluated group have carabelli trait and 33.1% of them haven’t this trait and from the group which have the carabelli trait 77.2% are bilateral, 22.8% are unilateral 116 sample of 180 male sample and 125 sample of 180 female sample have carabelli trait which according to Chi-square and PValue test are more than 0.05 and in 241 sample which have carabelli trait, 101 sample (49.9%) have develop form of this trait in the form of cusp. Present of this trait in the Iranian community are noticeable which was usually bilateral a have no specific relation with sex.

Dental alloys have a close contact to oral tissues. Following the corrosion phenomen the possibility of changes in surrounding tissues will exist. Due to different applications and suitable properties, dental alloys are very usefull, because of close relationship to restorative dentistry between alloys and tissues; they should be biocompatible & should not be cytotoxic. Base metal alloys are used in construction of prostheses frequently and are manufactured in Iran as well. Existence of some alloying elements such as Nickel or Beryllium has suitable effects like Protection against undesirable Oxidation or strengthening connection and also other profits. In parallel manner, they have some defects such as release Ion in oral environment and creation histotoxicity. The purpose of this study was to investigate and compare cytotoxicity of three types of nickel – chromium base metal alloys (Wirron 99, Verabond II, Supercast). With regard to different amounts of beryllium that have unique Delaminating properties, on mouse fibroblast cell (L922) In experimental study, 12 disks of each alloy with 5mm diameter and 2.5 mm thickness were prepared and placed in RPMI culture medium for 48 hours & 72 houres (extract medium). Then the extract mediums were diluted in two different dilutions of 200 & 40 and their cytotoxicity were evaluated by MTT assay and compare with two control groups consist of only culture media & culture media with teflon. The amount of Nickel, chronium, copper, zinc & silver released from each alloys were measured by flame atomic abosorption device. After 48 hours, no significant difference in cytotoxicity was found between samples and control groups (P>0.05). After 72 hours samples were not significantly different from each other in cytotoxicity, but there was a significant difference between samples and control groups. There was no significant difference in cytotoxicity with two dilutions of 200 & 40 between samples. Maximum release of nickel and chromium were observed from VeraBond II and zinc from Supercast. the cytotoxicity of three Nickel-Chromium alloys and one high noble which were used in this study was not different. There was some degree of cytotoxicity when the time duration of contact between cells and sampels were increased.

Root canal therapy, like other dental treatments, faces a number of unexpected complications, perforations being the most important of all. The main goal of perforation management is to rapidly and securely seal the perforated area to prevent bacterial influence and leakage. With this regard, this study aimed to compare the amount of microleakage between three brands of MTA (ProRoot MTA, White MTA and Iranian MTA. This experimental study was conducted on 51 human mandibular extracted molars. After sealing the perforated area by MTA, microleakage was evaluated using dye penetration and then clearing technique. Results were statistically analyzed using SPSS software and Kruskal Wallis test. Microleakage found to be least in ProRoot MTA and equal in MTA White and Root MTA. Differences, however, were not statistically significant (P=0.6). The most involved teeth belonged to MTA White and the least belonged to ProRoot MTA. Again differences were not significant. This study revealed the high efficiency of MTA in sealing the perforated forcations and the Iranian brand would not be exception. Due to the low number of available studies on the subject of Iranian MTA`s efficiency in sealing the perforations, it is highly recommended to conduct more investigations in this regard and compare the results.

Mandibular fractures depend in many factors like: muscle traction, force direction, … Traffic accident and fall from height are the most common reason for maudibular fractures.Matrials and The aim of this study is to determine type and site of mandibular fracture and its relation to eatiology of fractures. This study was done in 358 patients with mandibular fracture (maxillofacial clinic, Shariati hospital1999- 2004). From 358 patients with mandibular fracture, 192 patients with complex fracture,124 cases with simple fracture and 42 cases accompany with other fractures. The male were 297 (82.96%) and female were 61 (17.04%) cases. The most common type of fracture was body fracture and less common type was coronoid fracture. Car accident is the major reason of fracture and the most fractures happened in summer (specialy in September). To control of drivers and license examination, Can improve and decrease the rate of mandibular fractures also to use the cascade in motorcycle driver is very important.

Recent studies have shown a relation between some ABO blood groups and increased susceptibility to fungal infections. The aim of this study was to determine the frequency of blood groups in patients with denture sore mouth. In this descriptive cross-sectional study, diagnosis of Denture sore mouth in patients with complete dentures, was made by direct clinical examination and confirmed by culture of microorganism. Type of blood groups, were determined by direct agglutination method, using monoclonal antibodies against A and B antigens. Data's were studied with SPSS software version. Among 100 (53 male, 47 female)53 patients that studied, so had a O blood group, 17 had A, 18 had B, and 12 had AB blood group The frequency of the O blood group had a higher percentage in patients with Denture sore mouth in comparison with the other blood groups.

Numerous studies have shown that NiTi rotary instruments can effectively produce a well-tapered root canal form, with minimal risk of transportation. This study aimed to compare of dentin removal from mesiolingual canal walls of human extracted mandibular first molars using liberator and K-FlexoFile. In this experimental study, the initial images of 40 mesial roots of extracted mandibular first molars were scanned at 2, 4.5 and 7 mm from the apex by CT Scan system. Samples were divided in two groups. F group was prepared with K-FlexoFile and L group was prepared with Liberator files. Post-instrumentation images was recorded. The amount of dentin removal and canal transportations were evaluated and analyzed by ANOVA and t-test. At the coronal level of F-group, the most removal was done from distobuccal wall (0/17 0/07mm)and it had significant difference with the least removal from mesial wall (0/10 0/07mm)(p<0.005).L group had the most removal from distal wall(0.18 0.07mm) and the difference from mesial(0.09 0.04mm)and lingual walls was significant(p<0.05).At The middle level, F group did the most removal from lingual wall which had significant difference with mesial and distobuccal walls(p<0.05). But there was no significant difference between dentin removal in L group at this level.At the apical level, in both of the groups, the most removal was done from lingual and mesial walls with no significant difference between them(p>0.05). At the coronal level,there was no significant difference between two groups in dentin removal and both of them especially Liberator,attacked danger zones.. At the middle and apical levels,both of the groups well did the most removal from the lingual thick wall.

TMD is a complicated and prevalent disorder in the dental and Maxillofacial patients. Some of the clinical signs and symptom of TMD that involve the TMJ and its associated structure are pain, click and limited mouth opening. One of the modes of management is the use of low level laser therapy. LLLT for TMD has been controversial. The aim of this study was to evaluate the effectiveness of LLLT in TMD patients. we performed a single-bind clinical trail on 48 TMD patients. The patients were randomly divided into experimental and placebo groups. In the study group, the patients were treated with LLL (980 nm, 80 Hz, 6 J) at tree points over the TMJ (ie, 2 J per point and 1.5 J at the other sites of muscle pain) for 1 min. in the placebo group, the laser device was adjusted in the same positions but without power emission. Effectiveness of LLLT for pain and clicking in the groups was evaluated. To compare the magnitude of click, the chi-square test was used, and for pain severity the Mann-Whitney U-test was used to analyze the results. the pain severity after treatment on day 4 in the experimental group was 2.4±1.36, which was significantly less than placebo group’s results of 4.4±1.84 (p < 0.001). Click reduction was 23.1% in the placebo group and 76.3% in the experimental group. The results were statistically significant for both pain and clicking without recurrence up to the 2-year follow-up period (p < 0.001). Low-level laser therapy (980 nm) was effective in management of TMD signs and symptoms and induced considerable reduction or elimination of pain severity and clicking. LLL applications can be an effective mode of management for selected patients with TMD.