This study evaluated the cleaning efficacy of a root canal system by Nd:YAG laser and rotary instruments. Sixty single-rooted human teeth were divided into four experimental groups (n=15). In the first group the teeth were prepared with a step-back technique using conventional K-files. In the second and third groups, tooth preparation was carried out using Nd:YAG laser and rotary NiTi instruments, respectively. Teeth in the fourth group were prepared by combined laser and rotary methods. The smear layer remaining on canal walls was then assessed by scanning electron microscopy in the coronal, middle, and apical portions. The comparison of smear layer removal efficacy between groups was carried out by Kruskal-Wallis and Mann-Whitney U tests. The mean grades of smear layer removal in rotary-laser, rotary, laser and step-back techniques were 1.34 ± 0.18, 2.2 ± 0.28, 1.91 ± 0.25, and 2.42 ± 0.19, respectively. On the whole, differences between rotary-laser and rotary groups, step-back, and the three other techniques (rotary, laser, and rotary-laser) were significant at p=0.034. Based on the findings of this study, the cleaning efficacy of rotary, laser, and rotary-laser techniques were better than the step-back technique and the combined laser and rotary technique was the most efficient method.
Background and aims. There is no report on the apoptotic impact of Allium sativum L.(Garlic) on the oral squamous cell carcinoma (KB); hence, this study was designed to survey the apoptotic effects of garlic fresh juice (GFJ) on the KB cells.Materials and methods. MTTassay (MicrocultureTetrazolium Assay) was carried out to evaluate the cytotoxicity of GFJ on KB cells. Furthermore, TUNEL(Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling)and DNA fragmentation tests were performed to determine if GFJ is able to induce apoptosis in KB cells. Also a standard kit was used to assess caspase-3 activity in KB cells. Also western blotting was employed to evaluate the effect of GFJ on Bax:Bcl-2 ratio.Results. Significant cytotoxic effects were observed for the minimum used concentration (1μg/mL) as calculated to be 77.97±2.3% for 24 h and 818±3.1% for 36h of incubation (P < 0.001). Furthermore, TUNEL and DNA fragmentation tests corroborated the apoptosis inducing activity of GFJ. Consistently, after treating KB cells with GFJ(1μg/mL), caspase-3 activity and Bax:Bcl-2 ratio were raised by 7.3±0.6 and (P <0.001) folds, respectively.Conclusion. The results of this study advanced that GFJ induces apoptosis in the KB cells through increasing caspase-3 activity and Bax:Bcl2 ratio which could be attributed to its organo-sulfurcomponents.
Background. Dental implants are utilized with an ever-increasing rate. One of the causes of abutment screw loosening has been identified as inadequate preload. The objective behind this study was to compare the maximum hand-generated torque for tightening abutment screws by professors and postgraduate dental students using a digital torquemeter with 0.1 N/cm precision. Methods. In a laboratory study conducted in Dental Implant Department of Faculty of Dentistry, Tabriz University of Medical Sciences, the maximum hand-generated torque for tightening abutment screws by professors and postgraduate dental students was investigated, using a digital torquemeter with 0.1 N/cm precision. Results. The participants consisted of 36 (41.9%) females and 50 (58.1%) males, totaling 86 participants, of whom 45 (46.87%) and 41 (53.13%) were university professors and postgraduate dental students, respectively. The mean age of the participants was 33.4±10.2 years with an age range of 25‒60 years; 50 (58.1%) participants were in the 25‒34-year, 23 (26.7%) in the 35‒47-year, and 13 (15.1%) in the 48‒60-year age range. The mean age of professors and postgraduate dental students was 41±8.3 and 25.1±3.3 years, respectively. The means of maximum torques generated by female and male professors were 14.3±3 and 20.8±4.2, respectively. The means of maximum torques generated by female and male postgraduate dental students were 14.7±3.4 and 18.7±4.3, respectively. Statistical analyses showed no significant differences between the mean maximum torques generated by professors and postgraduate dental students (P=0.051). Conclusion. In the present study, the mean maximum torque generated by professors was higher than that generated by postgraduate dental students. However, the difference was not statistically significant. The mean maximum torque generated by male subjects was significantly higher. No interaction was seen between the studied groups and sex. However, there was a statistically significant difference between the mean maximum torques generated in different age ranges; i.e., the maximum torque generated in the 25‒34-year age range was lower than that in the other two age groups. Finally, the effect of age range on the mean maximum torque was similar in both groups.
Introduction: Despite a decrease in the number of adult edentulous individuals, the number of individuals who lose all their teeth and need complete dentures is on the increase. One of the most important principles of fabrication of complete dentures is to achieve patient satisfaction. In the present cross-sectional study, the gradual trend of patients' satisfaction with complete dentures was evaluated. Materials and methods: In a descriptive study with pre-and post-test design, carried out in 2013 on 30 patients referring to the Department of Prosthodontics, Tabriz Faulty of Dentistry, the patients' gradual satisfaction with complete dentures was evaluated one week and 2 months after delivery of dentures in 7 aspects, including masticatory efficacy, satisfaction with mastication of soft and hard foods, ease of cleaning of dentures, perception of food tastes, articulation and overall satisfaction. A researcher-made questionnaire was used, whose validity and reliability had been confirmed. The questionnaire determined the patients' satisfaction by a value ranging from zero to 10. Repeated-measures ANOVA was used to analyze data. Results: Thirty subjects were included in the present study. Changes in patients' satisfaction from the first week to the second month were significant in terms of mastication of soft and hard food items, ease of cleaning the dentures, articulation and overall satisfaction (P=0.022, P=0.023, P=0.018, P=0.001 and P=0.001, respectively). Changes in patients' satisfaction with masticatory efficacy and perception of food tastes from the first week to the second month were not statistically significant (P=0.092 and P=0.144). Conclusion: In the present study, patients' satisfaction increased in all the aspects. Although such increase in satisfaction with mastication of soft and hard foods, ease of cleaning the dentures, articulation and overall satisfaction was statistically significant, it was not significant in relation to perception of food tastes and masticatory efficacy.
Background. This study aimed to evaluate the effect of an increase in fixture thread face angle on the amount and distribution of stresses in the surrounding bone of implants with four different thread shapes by three-dimensional finite element analysis. Methods. Eight different fixture designs, with v-shaped, buttress, reverse buttress, and trapezoid threads, and two face angles of 20 and 35 degrees, were modeled using a software program. Each model was affected by two static forces with different values and angles (200-N axial 0° force and 100-N 45° oblique force) to compare the distribution of stress in different fixture designs. Results. The maximum von Mises stress was detected in v-shaped threads. An increase in the angle of the threads to 35° significantly decreased maximum von Mises stress in cortical bone in v-shaped and reverse buttress threads; however, the von Mises stress in the trapezoid and buttress threads increased with an increase in the thread angle. Conclusion. Under the limitations of this study, although the shape of the thread and thread surface angle does not have a definite role in stress distribution in the bone surrounding the implant, they are effective in the amount and type of stress induced in the bone supporting the implant.
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