Journal of Dentistry, Shiraz University of Medical Sciences
Volume:8 Issue: 2, 2007

Statement of problem: Basically as a matter of fact, it is important to determine the status of third molars before many of the children's dental treatment. The pattern of development and growth of face, jaw and teeth differs from race to race. Therefore, studies on the third molar status in each population seem to be an important issue. This study was performed to determine the pattern of the third molar development in a group of Iranian children and adolescents, in order to province a suitable reference for clinical use and future studies. In this descriptive study, 757 panoramic radiographs of patients, 6-16 years old, were investigated and the development of the third molars was categorized based on nine stages. The data were analyzed with chi-square and paired samples tests. The most important results of this study were:1. The earliest and latest ages with the possibility of observing the signs of wisdom tooth crypt in panoramic radiographs, were six and 14 years respectively. 2. Among the investigated ages, the highest possibility of observing finding the first sign of third molar crypt emergence was found to be at the age of nine.3. Possibility of the third molar existence after age of 10 reduces about 53% in comparison to the earlier ages.4. There was a significant difference between age and the third molar developmental stage in each four quadrant (p=0.000). Determination of the pattern of third molars development stages is useful in clinical diagnosis and comprehensive treatment plan.

Statement of problem: Management of open apices teeth is one of the most serious problems for dentists. Contemporary endodontics proceeds to single step techniques such as apical plug and customized cone for management of these cases. The purpose of this study was to compare apical microleakage between customized cone and apical plug techniques on open apices polyester made root canals. In this in vitro experimental study, 68 clear models were made from polyester in two different forms: S models (round canals), and L models (oval canals). Thirty models (15 S and 15 L) were obturated with customized cone technique and 30 models (15 S and 15 L) were obturated with apical plug technique using Ca(OH)2 as an apical barrier. Eight models were considered as positive and negative control groups. Models were immersed in methylene blue for 48 hours and maximum linear dye penetration of each was measured by three separate observers. Student t test was used for statistical analysis of the findings. The results illustrated that the mean leakage of the customized cone group was statistically greater than apical plug group (p<0.05). In addition, when comparing L and S models in customized group, L models showed more linear leakage than S models (p<0.05), but this difference was not significant in apical plug technique. The finding of this study indicated that the apical plug technique, when using Ca(OH)2 plug as a barrier may produce a better apical seal than the customized cone technique in short term.

Statement of problem: Taking impression plays an important role in prosthodontic treatments. Alginate impression materials are very common in this regard. With due attention to the importance of setting time and consistency of impression materials, researches for comparison the properties of different impression materials are necessary. This study was conducted to investigate the setting time and consistency of two Iranian alginates (Regular Iralgin and Super Iralgin) in comparison with one imported brand, Bayer alginate using ADA (No.18) and ISO (1563) specification. In this in vitro study, 51 samples (17 samples of each alginate, Bayer, Regular Iralgin and Super Iralgin) were prepared. Setting time and consistency of these materials were compared according to Iranian standard Institute, specification 1563. To analysis the data, t-test and ANOVA were used. Mean of consistency and seting time from maximum to minimum was including Bayer, Regular Iralgin and Super Iralgin. According to the result of this experiment, the three materials showed acceptable setting time and consistency according to Iranian Standard Specifications. ANOVA analysis showed no significant differences in consistency among these materials (p>0.05) whereas there were significant differences in setting time between Bayer alginate and Iranian brands (p<0.05). The three impression materials used in this study showed acceptable setting time and consistency. There was significant difference in setting time among them, which could be related to the composition of these materials. More studies are needed to be conducted on other properties of these materials.

Statement of problem: As for other dental treatments, root canal therapy may lead to failure. Correction of these conditions will be faced with problems and complexities, particulary if any periapical lesion is peresent. The aim of this study was to evaluate the success rate of retreament in teeth with apical lesions.Materilas and In this descriptive study 60 teeth with failed root canal therapy which had been retreated by an endodontist were reevaluated clinically and radiographically between 6 to 12 monthis after retreatment. Clinical examinations were performed by a clinician and comparison with the primary symptoms, recorded in patiants file, was obtained. Periapical radiographs were prepared by parallel technique and E speed film with the same proccessing conditions. Periapicel lesion size was evaluated and comparison was made before and 6-12 month after retreament, using photoshop software (version7). The data were analyzed by chi-square test and agreemental tables. Statistically, there was no correlation between variables and success rate. The success and failure percentage of retreatment was 81.7% and 5%, respectively and 13.3% of cases were uncertain. The most success rate was observed in group of 31-40 years old (95%), keeping in mind that most patients were in this age group. The least success was in group over 50 years old According to this study, the high success rate could be expected in retreatment of teeth with periapical lesion.

Statement of Problem: Tooth size discrepancies (Bolton ratio) affect the best possible esthetic and functional results at the end of treatment. The extraction decision is the most critical decision when planning treatment, and the premolars are the most common teeth in this decision. The purpose of this study was to compare the effect of different patterns of premolar extraction on tooth size discrepancy at the end of orthodontic treatments. This cross-sectional study was carried out on 200 study models of the patients (145 females and 55 males) who were selected through available selective sampling method. The greatest mesiodistal width of all teeth were measured except for the second and third molars. The measuring was done by a digital caliper with 0.01mm accuracy. According to calculated Bolton overall ratios, the patients’ casts were divided into three groups: NB (Normal Bolton), DB (Decreased Bolton), and IB (Increased Bolton). This classification was based on the overall Bolton normal values plus or minus one standard deviation. The Bolton overall ratios of each group were measured before and after hypothetical extractions of different four premolars. The data was analyzed using one way ANOVA, and the paired t-test was used for comparing the ratios between males and females. The results showed that there was no significant difference between males and females in Bolton overall ratios. Significant differences were found between overall ratios for different combinations of premolar extraction before and after extractions. The Bolton overall ratios showed to be smaller after premolar extractions in each group. After premolar extractions, some patients in the NB and IB groups were transferred to the DB, and NB group respectively. According to the results of this study four premolars extraction causes a decrease in Bolton overall ratio and in some patients, increased overall ratios could be corrected to normal values after removal of second mandibular premolars.

Statement of Problem: Successful endodontic therapy depends on a well-adapted filling in conjunction with root canal. The proper restoration requires the placement of a post and core. Therefore, the time of post space preparation, and its possible effect on the quality of the apical seal is important. The purpose of this study was to compare the effect of immediate and delayed post space preparations on apical seal using two currently used sealers; AH26 and Apexit sealers. Seventy six extracted anterior teeth were used in this experimental study. Teeth were randomly divided into four groups and all canals were prepared by step back method, and then filled with gutta percha by lateral condensation technique. AH26 was the sealer used in groups 1 and 2, while in groups 3 and 4 Apexit sealer was used. In groups 1 and 3, post spaces were immediately prepared. But in groups 2 and 4 they were prepared after one week. After preparation, the teeth were immersed in India ink for 3 days and finally, were cleaned. The extent of dye penetration was determined by stereomicroscope. The data were obtained and analyzed statistically with ANOVA, Tukey and T.tests. The results showed that the lowest and highest rates of dye penetration were detected in groups 1 and 4 respectively. There was significant difference in apical leakage between the AH26 immediate, and Apexit delayed post space preparation. According to the results of this study, the immediate preparation of post space after obturation and before setting of the sealer is recommended.

Statement of Problem: Candida is an opportunistic organism which will become pathogen if predisposing factors are present. One of the predisposing factors for increasing prevalence of candida is the use of corticosteroids. Researches on candida infections in treated patients with inhaled corticosteroids are controversial. The purpose of this study was evaluating the effect of two inhaler corticosteroids (Fluticasone and Beclomethasone) on the number and frequency of candida species in saliva and its comparison with normal subjects. This experimental research was performed on three groups of individuals. The first group was 30 asthmatic patients used inhaler Fluticasone, the second group with the same number of patients used inhaled Beclomethasone and the third group was composed of 60 normal individuals as control. Subjects were selected after evaluating the medical history and assurance of absence of the predisposing factors. Subjects’ saliva were gathered in sterilized tubes and cultured in chromagar media for evaluating the type of candida. The results were analyzed with oneway and tukey tests. Based on this study, the number of candida species was significantly different among the three groups. The number of candida species in patients used fluticusone was higher in comparison with the other two groups (p<0.001). This study showed that the number of candida species in patients treated with corticosteroids inhaler was high in comparison with the control group. Thus for avoiding candida infection, proper oral heath and prevention of predisposing factors in these patients are recommended.

Statements of problems: While there are multiple components of preventive programs developed for caries prevention in children, perhaps none is as important and effective as the appropriate use of fluoride. The primary caries preventive effects of fluoride result from its topical contact with enamel and through its antibacterial actions. Till now bulk of research exists which has compared the antibacterial effects of ordinary topical fluoride gels & solutions. Little or no evidence is seen to tell us which topical fluoride including varnishes is more antibacterial. We suggested further research about antibacterial effect of APF gel and NaF varnish against cariogenic microorganisms (streptococcus mutans & lactobacillus), so use of these may have benefit in reduction of caries. Comparison of inhibitory effect of NaF-varnish versus APF-gel on concentration of cariogenic bacteria (streptococcus mutans & lactobacillus), was the primary goal of this research. In this exprimental study, twenty premolars were sectioned buccolingually. With the use of "window method" certain surfaces of enamel were covered with APF-gel and NaF-varnish. Then, the number of streptococcus mutans and lactobacillus were counted after 18, 24 and 48 hours. In the "Disk diffusion" method the streptococcus mutans with the concentration of 108/ml and volume of 0.1cc were introduced to the M.S.Media culture after application of APF gel and NaF varnish. Then the inhibition zone, measured. Statistical analysis in this research was multilevel modeling. The comparison between gel and varnish after 18, 24 and 48 hours showed that gel has more effect than varnish over the number of lactobacillus. The difference with lactobacillus was statistically significant (p<0.005), but with streptococcus Mutans was not. APF gel was more effective (70.23%) than NaF varnish. Based on the obtained results, APF gel can be used with more thrust than NaF varnish in caries prevention.

The aim of this case report is to present an unusual maxillary first molar with a single root and a single canal. The significance of this case is that, according to most endodontics and dental anatomy textbooks, the human maxillary first molar usually has three roots and three or four canals. Based on our literature search, this case report is the second reported maxillary first molar with single root in the world and the first in Iran. A 42 years old lady with acute pulpits of the left maxillary first molar was referred to our clinic. The probability of the presence of single root and single canal of the first molar was considered based on her panoramic view. Access opening revealed a single wide canal orifice extending from buccal to lingual side. The presence of a single root and canal was proved by preparing several periapical radiographs with different horizontal angulations during root canal therapy.