[In vitro microleakage evaluation of total-etch and self-etch bonding systems]

Bonded restorations have a number of advantages over traditional, non-adhesive methods. Adhesion reduces the microleakage at the restoration-tooth interface. Prevention of microleakage, or the ingress of oral fluids and bacteria along the cavity wall, reduces the clinical problems such as postoperative sensitivity, marginal staining, and recurrent caries, all of which may jeopardize the clinical longevity of restorative efforts. The aim of this study was to evaluate the microleakage in class V composite restoration with total-etch and self-etch adhesive systems. In this in-vitro study, 48 standard class V cavities were prepared in the buccal surface of human extracted premolars so that the occlusal margins of the cavities were in the enamel and the gingival margins in the dentin [cementum]. The teeth were divided into two groups of 24. In the first group, the cavities were restored with total-etch system [Excite] and composite. The teeth in the second group were restored with self-etch system [Prompt L-Pop] and the same composite. The teeth were thermocycled 500 times between 5 - 55°C and then were covered with nail-polish and adhesive wax axcept for 1 mm around cavities, and all teeth were immersed into the 2% methylene blue for 10 hours. The samples were mounted in polyester blocks, sectioned longitudinally at the middle of the cavities, and evaluated for microleakage under a stereomicroscope at 40x magnification. Dye penetration was scored between 0-3. Data were analyzed with Mann Whitney and Wilcoxon tests. In the enamel and dentin margins, microleakage for the total-etch group was found to be less than the self-etch group [p < 0.05]. A significant difference in the microleakage mean rank of the enamel and dentin margins was observed [p< 0.05]. Microleakage in the enamel margins was less than that in the dentin margins. Total-etch adhesive system showed a significant difference on the microleakage of class V composite restorations especially in the enamel margin

use of orthodontic need index [IOTN] in a referred Iranian population

IOTN index has been used in different countries for assessment of orthodontic treatment needs in recent years. This index has two components, an aesthetic component [AC] and a dental health component [DHC]. The aim of this study was assessment of orthodontic needs on the basis of IOTN index in those people who had come for orthodontic treatment. We used IOTN index in order to assess the orthodontic treatment needs of 343 applicants [262 females and 81 males] with a mean age of 18.1 [standard deviation 3.8 years]. Who had come for treatment during a certain period of time [8 months] For determining the AC we used a set of 10 pictures graded on the basis of aesthetical features of teeth. The DHC Component of Index that has five degrees was determined bases on study casts with standard preparation. If necessary and for more accuracy panoramic radiographies of patients were also used. The analysis of the obtained data was performed using Kappa, Chi-square and Spearman's tests. The results with determination of subjective needs on the basis of AC by patient's perceived need indicate a lock of significant relation between gender and the patients' perceived need for AC [p<0.05]. Most of these patients had determined their AC to be between grades 1-4, the results of AC determination through normative need assessment were the same as the results of perceived need Assessment. Which in case of DHC determination it was revealed that most subjects had a grade between 4 and 5, and there was a significant relation between DHC and type of malocclusion [p>0.05]. Subjective data of IOTN index alone can not be considered an appropriate indicator of orthodontic treatment needs determination

[Astigmatism reduction in frown incision Phacosection]

Cataract is a type of tarnish observable opacity in different layers constituting the lens and will cause light occlusion or scattering. Necessity for treatment of Cataract via surgery and its close relation with corneal astigmatism, when we applied a new method in cutting and type of cataract surgery, led us to measure the post-operation corneal astigmatism changes in frown incision Phacosection. This interventional study has been done on 73 eyes[58 patients]. These patients were gone under Cataract surgery via no stitch frown incision scleral tunnel phacosection method. In this study we have 7mm external scleral incision with no suture. They were Keratometerized in four separate periods including pre-operation, one week, one month and three months post- operation. Data was analyzed using independent and paired t-tests. Age, sex and left or right eye had no influence on astigmatism. Mean pre- operation astigmatism was 0.84 +/- 0.87D, mean astigmatism 1 week post- operation was 0.27 +/- 0.88 D, 1 month post- operation 0.06 +/- 0.82 D, and three months post-operation was -0.03 +/- 0.85 D [P= 0.0001]. Before operation, 80% of the patients did have an astigmatism rate less than 1D that increased to 94.5% in three months period after operation and in 89% of the cases, the ultimate change in astigmatism has been found lower than 1D. The obtained information revealed that there is a meaningful difference between pre-operation astigmatism and the same after one week, one month and three months post-operation[P= 0.0001]. Independent sample t and paired t-test were used to analyse data. Our study indicated that the no stitch frown incision scleral tunnel phacosection surgery can reduce pre-op corneal astigmatism, and because of induction of the slight controlled astigmatism we can apply this technique for all cataractic patients

[Evaluation of antimicrobial effects of different calcium hydroxide preparation methods with direct exposure test]

Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in the root canal and now is widely used as an intracanal medicament in endodontic therapy. The aim of this study was to evaluate the antimicrobial effect of different calcium hydroxide preparations with Normal saline, Lidocaine 2%, Chlorhexedin 2% and 0/2%, Iodine Potassium Iodide 2% and Glycerin on Entrococcus faeealis with direct exposure method. For conducting this experimental in-vitro study 375 sterile paper points were contaminated with the microbial suspension of Entrococcus faecalis. The samples were placed in sterile dishes and covered with creamy mixture of six different calcium hydroxide preparations. After 1.3, and 7 days tile paper points were immersed in test tubes containing BHI. Microbial growth was evaluated by turbidity in culture mediums. Data obtained showed that all of tested materials had perfect antimicrobial action but only in calcium hydroxide with Chlorhexidine 2% and 0.2% groups perfect antimicrobial action and no microbial growth was observed after 24 hours. Regarding the results of this study it is concluded that the vehicle of calcium hydroxide has not any significant effect on its antimicrobial activity, however, more studies on the effect of vehicles of chemical properties of calcium hydroxide such as its diffusion in similar conditions of root canal system, are needed

[ effect of light-curing time to adhesive layer on shear bond strength of composite to dentin]

For reducing light exposure time of tooth-colored restorations, and chair time reduction, different experiments have been conducted. The purpose of this study was to determine the effect of different light exposure times to adhesive layers [Excite and Prompt L-pop] on the shear bond strength of dentincomposite interface. In this in-vitro study, 72 human intact premolar teeth were mounted in acrylic casts and enamel buccal surfaces were removed. The bonding surfaces were equalized using a surface index. Teeth were divided into six equal groups each of 12 [A, B, C, D, E, and F]. According to the manufacturer instructions, Excite adhesive in groups A, B and C, and prompt L-pop in groups D, E and F was used. A and D groups were not exposed to light, but the exposure time in groups B, E and C, F was 20s, and 40s respectively. After one week of storage in 37 degree C water, synergy composite resin was applied and then was exposed to light. The specimens were loaded by shear force with 1 mm/min cross head speed. Data were analyzed by two-way analysis of variance [ANOVA]. The means shear bond strength of groups A,B,C,D,E, and F were 3.9, 13.45, 18.1, 8.3, 24.81, 24.99 Mpa, respectively. The differences between shear bond strength of groups A, B and C and between groups B, D were statistically significant [p=0.0001]. However, the differences between groups E, F were not statistically significant. In all exposure times, the bond strength of Prompt L-pop was significantly higher than that of Excite. According to the results of this study, increase in the light exposure led to the higher bond strengths in Excite groups. In Prompt L-pop groups, 20s exposure time was adequate and by increasing the light exposure time, shear bond strength was not affected. Without light exposure in both materials, the least bond strength for the composite resins was not attainable

Antibacterial substantivity of three concentrations of doxycycline on bovine root dentin infections: an in vitro study

The aim of this in vitro study was to compare the antimicrobial activity and substantivity of three concentrations of doxycycline on bovine root dentin infections. Seventy dentin tubes prepared from intact bovine incisors were infected in vitro for 14 days with Enterococcus faecalis. The specimens were divided into five groups according to the used intracanal irrigation as follows: Group 1: l00mg/ml of doxycycline hydrochloride solution [DHS] [n=20]; Group 2: 50mg/ml of DBS [n=20]; Group 3: l0mg/ml of DHS [n=20]; Group 4: positive control [infected dentin tubes] [n=10]; and Group 5: sterile saline [negative control] [n=10]. Dentin chips were removed from the canals with sequential sterile low - speed round burs with increasing diameters of ISO sizes: 025, 027, 029, 031, and 033 at experimental times of 0, 7, 14, 21, and 28 days. After culturing, the numbers of colony-forming units [CPUs] were counted. Data were analyzed using analysis of variance and covariance with repeated measures [ANOVA] to indicate differences between the experimental groups and the positive control. One-way ANOVA [Tukey's method] was used to indicate differences within each layer. The numbers of CFt/s in aJJ three experimental groups were minimum in first cultures, and the obtained results were significantly different from each other at any time period [P<0.05]. In first culture, the groups 1 [0.400 +/- 0.699] and 3 [4.700 +/- 3.683] showed the lowest and highest numbers of CPUs, respectively. In each group, the numbers of CPUs increased significantly by time lapse [P < 0.05]. Under the conditions of this study, it can be concluded that doxycycline HC1 may be useful as a substantive antimicrobial agent

Effect of salivary contamination on shear bond strength of composite resin used between teeth and brackets

Enamel contaminations with salivary proteins or blood are the major reasons for debonding of brackets. The purpose of this study was to evaluate shear bond strengths of bonded brackets with enamel surfaces under different conditions. The Concise composite [3M, Unitek] was used for adhesion of 0.018 inch standard brackets [3M, Unitek]. Fresh human saliva was used for contamination of enamel surfaces. 90 teeth were divided into 6 groups: 1- No surface contamination, 2- Contaminated after etching, 3- Contamination after application of bonding resin, 4- Contamination after etching, then re-etching, 5- Contamination after resin bond application, then re-etching and 6- Contamination after resin bond, then application of resin bond again. Surface contaminations were dried in all groups. After bracket bonding, the samples were held in distilled water in 37°C for 24 hours. Specimens were then thermo-cycled for 650 times at 5°-55°Centigrade. Shear bond strengths were measured by DARTEC machine. Data were evaluated by Duncan and variance analysis. Statistical analysis of data reveals significant differences only in groups one and four [P < 0.05]. The maximum shear bond strength was observed in the fifth group [21.61 +/- 2.6 MP] and the minimum in the third one. After salivary contamination of enamel, adequate clinical shear bond strength can be gained with drying of contaminated area and re-etching for 10 seconds. No washing is required in this case

Root canal morphology of human mandibular incisors in Yazd province

An in vitro study was performed to determine the number and the type of root canals of mandibular incisor teeth in an Iranian population. Sixty eight mandibular incisor teeth were immersed in India ink decalcified and cleared. It was found that 55.9% of the teeth had two canals that in 51.5% of them the canals merged into one canal before exiting the tooth through one apical foramen. Because of high percentage of two canals in lower mandibular incisors, there should be more attempt to detect the second canal during access preparation

Comparison between the accuracy of digital and conventional radiographies for evaluation of the curved canals length

Proper cleaning and shaping of the root canal system is one of the most important aspects of endodontic therapy. To estimate the canal length before instrumentation in endodontic treatment, traditionally, conventional radiographic techniques and, recently, Direct Digital Radiography [DDR] are applied. The application of computer technology in radiography has allowed less exposure time for image acquisition, better storage and retrieval, and transmission to remote sites in a digital format, elimination of processing, and a considerable time saving. The purpose of this study was to compare the accuracy of DDR and conventional radiography in determination of working lengths of curved canals in first mandibular molars. Forty extracted human first mandibular molars with root curvature were selected. Samples were divided into two groups: With root curvatures less and more than 25[o]. The samples were mounted in plaster blocks and their canal lengths were estimated by using DDR and conventional radiographs. Regression analysis, correlation coefficient, and t test were used for statistical analysis. In spite of the greater accuracy of conventional radiography in canals with curvature <25[o] and the greater accuracy of digital radiography in canals with curvature >25[o], the differences were not statistically significant. Both conventional radiographs and DDR can be used to determine working length during endodontic therapy

Risk factors and laboratory diagnostics for post renal transplant tuberculosis: a case-controlled, country-wide study on definitive cases

Tuberculosis [TB] is a common cause of morbidity and mortality in renal transplant recipients. It is usually misdiagnosed because of lack of medical awareness and its infrequency in renal transplant recipients. 44 cases [0.3%] with post-transplant TB out of 12820 patients who had renal transplants performed between 1984 to 2003 were found from the hospital records of 12 major kidney transplantation centers in Iran. These cases were compared with 184 healthy transplant subjects whose transplants were performed by the same surgical team as the controls. The mean age of cases and controls was 37.7 [13-63] and 35.6 [8-67] years [p=0.3], respectively. The mean duration of pre-transplantation hemodialysis was 30.3 [3-168] months in cases and 18.2[1-180] months in controls [p=0.03]. A past history of tuberculosis was detected in 2 cases and 1 control [p=0.3]. The mean doses of initial and maintenance immunosuppressive drugs in cases and controls were not significantly different. A total of 25 cases [56.8%] and 60[32.6%] controls had rejection prior to diagnosis of TB [p=0.004; OR=2.7, CI95%: 1. 3-5.6]. To our knowledge, this is the first study that demonstrated increasing risk of post-transplant TB by extending the duration of pre-transplant hemodialysis and the number of post-transplant rejection episodes. Further study is needed to clarify our new findings specifically in respect of different immunosuppressive regimens

[Levator aponeurosis resection versus Muller's muscle-conjunctival resection for the correction of minimal blepharoptosis]

Purpose: to compare the results of levator aponeurosis resection and Muller's muscle-conjunctival resection in the correction of minimal blepharoptosis

Methods: this randomized controlled study was conducted on 20 patients with minimal ptosis [<2 mm and >1 mm] and good levator function [>10 mm] which were assigned to one of two surgical groups: levator aponeurosis resection group or Muller's muscle-conjunctival resection group. Patients were visited on days 1, 3, 7, and 14 and at months 1, 2, 3, and 6, postoperatively to evaluate the symmetry, lid contour, lid crease position, lagophthalmos, lid lag, suture keratopathy, and dry eye

Results: postoperative symmetry was found in 8 cases in both group. Lid crease position symmetry was found in 9 and 5 cases in levator and Muller groups, respectively [P= 0.23 5]. Lid lag was found in 7 cases of levator group [mean= 1.15 mm] and 3 cases of Muller group [mean= 0.5 mm] [P= 0.123]. Mean lagophthalmos was 1.75 mm and 1.15 mm in levator and muller groups, respectively [P= 0.749]. No patient had abnormal contour, suture keratopathy, or dry eye symptoms or signs. Exposure keratopathy occurred in 2 cases of each group

Conclusion: Muller's muscle-conjunctival resection is at least effective as levator aponeurosis resection in correcting minimal blepharoptosis in patients with good levator function and symmetric lid crease