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"nBackground and Aim: Pit and fissure sealant therapy, is one of the most effective methods, in prevention of occlusal caries. Saliva contamination before curing the resin can increase the risk of failure in this method. The purpose of this study was to evaluate the effect of saliva contamination prior to curing on microleakage of pit and fissure sealants. "nMaterials and Methods: In this experimental in vitro study 21 sound human pre molars were selected and two standardized V-Shaped fissures were prepared on both buccal and lingual surfaces, then they were randomly divided into two equal groups. In the control group, the sealant was cured without any saliva contamination and in the case group, the sealed teeth were immersed in artificial saliva for ten seconds before curing. After thermocycling the samples were immersed in 2% fouchsin solution for 24 hours and then sectioned longitudinally in bucco - lingual direction. The specimens were then fixed and assessed under stereomicroscope to determine microleakage and dye penetration using paired student t. test. P

Background and Aim: The need for recrimping precrimped stainless steel crowns by the dentist in clinic is controversial. This study aimed to evaluate the rate of marginal circumference and marginal thickness change of precrimped stainless steel crowns after recrimping. Materials and Methods: In this experimental study, 30 primary photos were taken from margins of 30 S.S.Cs (3M, Ni-Cr) related to tooth 85 with a digital camera fixed at a determined distance. Margins of crowns were crimped by 114 and 137 pliers with a controlled force (0.2 N) and then 30 secondary photos were taken in the same conditions. The circumference of crown margins in primary (group A) and secondary (group B) photos were assessed by a digitizer system. Comparing the circumferences of crown margins in primary and secondary photos showed a significant decrease after crimping. Thickness of 30 random points on the crown margins of a crown similar to mentioned cases was measured by SEM (×150). Then similar procedures including taking a primary photo, crimping and taking a secondary photo was done for the sample crown. After significant reduction in margin circumference, thickness of 30 other random points on the crown margin were measured by SEM. Data were analyzed by paired sample t-test with p

Statement of Problem: Previous experiences and clinical observations indicate that enamel hypoplasia and hypocalcification of first permanent molars, among infants born in Cessarian Section Delivery (C/S) is more common than those born in Normal Vaginal Delivery (NVD). Moreover, the first permanent molar is the only tooth that its "cusp tip calcification" starts exactly at the time of delivery. Purpose: The aim of this research was to investigate the relationship between delivery type and clinical feature of the first permanent molar. Meanwhile, the different effects of the elective and selective types of cessarian, on the clinical feature of first permanent molar, were studied."nMaterials and Methods: Birth files, relation to the year 1994 and before, were extracted from a gynecologist clinic. One hundred patients with NVD, 50 patients with selective cessarian delivery and 50 patients with elective cessarian delivery were chosen to examine clinical feature of the first permanent molars of their children. The children, 6 years old or more, were examined. The medical information of the mother were extracted from her file and that of child, were asked from the mother. To analyze the"nresult, X lest- was used."nResults: The prevalence of enamel defects (hypoplasia and hypocalcification) of the first permanent molar among children born by C/S, were significantly different from the children born by NVD (P=0.0002). Mean while, the prevalence of these enamel defects in the selective cessarian delivery was more than elective cessarian delivery (17% vs. 9%), which was not statistically significant (P-0.07) Conclusion: It is suggested that gynecologists, pediatricians and pedodontists provide the parents with necessary information about the child's first permanent tooth and ask them to pay enough attention to keep this tooth which is considered as the key of occlusion.

In this study, by cluster simple random sampling, the prevalence of ectopic of first permanent molar in 8 years old Tehran school children is considered and determined as 0.87 percent The involvement of maxilla was more than mandible and the difference was significant. Bilateral involvement was more than unilateral and boys were more- than girls, how ever the differences were not significant."nAs for as the geographical distribution is considered, the differences were not noticeable, either.

One patient with Ellis Von Creveld syndrome contains: dwarfism, congenital heart"ndisease, ectodermal dysplasia, polyductyly, an abnormally wide labial frenum and maxillary"nmolars with single root.

Statement of Problem: DMFT and OHI- S indices are two of the most important quantitative factors, measuring tooth health and oral hygiene, respectively. Propose: The aim of this study was to study of correlation between these indices in 12- year old school girls of Kashan. Materials and Methods: A cross sectional study on the correlation between these indices were carried out on 242, twelve year- old school girls in Kashan and the results, have been presented in this paper. Results: The findings were as follows: Average and standard deviation of decayed, missed and filled teeth were (1.12, 1.5), (0.05, 0.25) and (0.28, 0.92), respectively. Average and standard deviation of DMFT was 1.45 and 1.73, respectively, with 45.5 percent of the cases being caries free (DMFT= O). OHI- S index, on the other hand, showed an average of 1.46 with a standard deviation of 0.42. Conclusion: The result of the 2.test, carried out on the measured data, showed no correlation between the DMFT and OHI-S indices.

Statement of Problem: Nowadays, evaluation of the development of occlusion in deciduous teeth for creating corrective occlusion in permanent teeth is one of the most important objectives of pediatric dentistry. In other countries, a vast number of researches have been accomplished on the details of occlusion in deciduous teeth. But, unfortunately, there is still no accurate information about this in IRAN. Purpose: The aim of this study was to evaluate the occlusion and interdental spaces of kindergarten children of Tehran. Materials and Methods: On this basis, some information were gathered by means of a cross-sectional, descriptive, analytic study on 248 children during their 4-5 years of age. All kinds of deciduous molar and canine occlusion were studied and registered. Anterior and posterior interdental spaces by means of a gauge with an accuracy of 0.05 mm were also measured. Collected data was analyzed by t-student and variance analysis. Results: In most children, the facial feature was mesoencephalic and the profile was convex. The incidence of occlusion was Fluch Terminal Plane (FTP), Distal Step (DS) and Mesial Step (MS), respectively. There was a statistical significant relationship between the FTP, DS and MS molar occlusion and the occlusion of Class I, II and III canine (P