Statement of Problem: Evaluation of new adhesives efficacy in BONDing orthodontic brackets to enamel has led to different results. The new measuring method, micro-shear BOND STRENGTH, is preferred as an accurate method due to its ability to reduce confounding factors.Purpose: The purpose of this study was to evaluate and compare the micro-shear BOND STRENGTH of three different adhesive systems for enamel surface preparation before bracket BONDing.Materials and Method: In this experimental study, 90 extracted premolars were randomly divided into three groups of 30. TransBOND XT was BONDed to enamel after enamel surface preparation with acid etch in the first (control) group, TransBOND plus self-etch primer in second group, and Adper prompt L-pop self-etch adhesive in third group. Then each group was randomly divided into two subgroups of 15. Micro-shear BOND test was performed after 24 hours (T1) and 3-months (T2). BOND failure mode was also evaluated according to Adhesive Remnant Index (ARI). Two way ANOVA and Tukey tests were used for BOND STRENGTH evaluation in groups, and mode of BOND failure was analyzed with Kruskall Wallis and Mann Whitney tests.Results: The highest BOND STRENGTH was found in acid etch group (29.17 MPa). Difference of BOND STRENGTH at two intervals was statistically significant in all groups ( p <0.001). BOND STRENGTH difference between T1 and T2 was also significant in three groups ( p <0.001). However changes over time in three groups did not reveal any significant differences ( p = 0.091). BOND failure analysis demonstrated significant differences in ARI between groups.Conclusion: BOND STRENGTH of acid etch group was the highest and self etch primer showed higher BOND STRENGTH than self etch adhesive group. Less adhesive remnant was found in self etch group.

Background & Aim: More than 30 years has passed since introduction of glass-ionomer cement as a dental restorative material, luting cement and liner. Although they are sensitive to moisture and desiccation during the initial setting stages, relative poor physical properties because of chemical BONDing to tooth substrate, and long-term esthetic quality, they are recommended for restoring anterior and posterior primary teeth, cervical lesions and root caries of permanent teeth. In this study, shear BOND STRENGTH of Fuji II was compared with of ariadent glass-ionomer cements. Materials & Methods: Thirty intact extracted primary molars were prepared for this study. Selected teeth were divided in two groups of 5. Sample were free of caries, fracture, crack, discoloration or any structural abnormality. The dentin of buccal surface of teeth were exposed by microtome apparatus. The surface was conditioned by polyacrylic acid (10%) for 20 seconds. Glass ionomer cements (Fuji II, and Ariadent) were prepared in a plastic cylinders (15 of each) and attached to the dentin of teeth horizontally. Shear BOND stength of materials was measured by instron (Model 1159).Results: Mean shear BOND STRENGTH of Ariadent cement was 4.2±1.9 Mpa while 7.4±1.5 Mpa was of Fuji II cement (P=0.000).Failure mode was similar between two cements (P=ns). The most prevalent type of failure mode was cohesive failure leaving a firmly attached thin and homogenous layer of cement to dentin, in both groups.Conclusion: It appears that shear BOND strenght of Ariadent cement to primary tooth is much lower than of Fuji II.

Aim: The aim of this study was to compare the etching effect of porcelain with Hydrofluoric acid (HF) one shear BOND STRENGTH using one coat BOND and self cure composite.Methods & Materials: The study was conducted experimentally using observation as its technique. 40 porcelain cubes were prepared and assigned into 4 groups. Group I specimens were treated with 35% phosphoric acid.Subsequently one coat BOND was applied to BOND the bracket, group II specimens were made fresh with fine diamond bur, treated with a 35% phosphoric acid and one coat BOND was applied to BOND the bracket, group III specimens were treated with a 20% hydroflouric acid (HF) and Nomix composite BOND was applied to BOND the bracket, group IV specimens were treated with a 40% HF acid and the same procedure in the group III was followed. The Instron machine was used at a crosshead speed of 0.5 mm/min to test the shear BOND STRENGTH.Result: The shear STRENGTH was 2.47±1.8Mpa for group I, 5.64±2.6Mpa for group II, 3.28±1.8Mpa for group III and 3.03±2.6 for group IV. The overall difference between the four groups was statistically significant (P<0.05). Conclusion: The use of fine diamond bur and 35% phosphoric acid for Etching and use of one coat BOND can achieve a successful BOND between either use only phosphoric acid or 20% HF acid-Etched with No mix composite and 40% HF acid etched with No mix composite.

Background and Aim: Nonmetallic tooth- colored posts adhere to canal walls by dentin BONDing agents and resin cements. Better retention and proper distribution of stress result from enough and proper BONDing. The purpose of this study was to evaluate BOND STRENGTH of D.T. Light - post with two different resin cements (selfcure & dual-cure) and to investigate the effect of irrigating solutions applied in root canal on BOND STRENGTH of the resin cements and D.T.Light- post to root canal wall.Materials and Methods: In this experimental study 40 single root teeth (maxillary canine & central) were selected and stored in 0.1% thymol solution for one week and transferred to distilled water. The teeth were decoronated 2mm above CEJ. The canal space was mechanically enlarged using k-files (up to # 70). The teeth were randomly divided into two groups. The first group was irrigated with 2.6% NaOCl, and the second was irrigated with normal saline. After drying, the teeth were filled with gutta percha cones using lateral condensing method. After two weeks the post space was prepared and D.T.Light- post was inserted in each subgroup using self or dual-cure cements according to manufacturer's instructions. After thermocycling, the apical part was cut 1cm below CEJ. The remained length was divided into 9 equal sequential sections. Each section was submitted to shear push-out test in universal testing machine. Statistical analysis of the BOND STRENGTH data was performed using ANOVA and post hoc tests with p<0.05 as the level of significance. All failed specimens were examined under stereomicroscope. Degrees of conversion (DC) of the cements were determined by FTIR.Results: Significant difference in BOND STRENGTH values were found among sites (P=0.001) and cements (P=0.03). With increasing in depth, BOND STRENGTH decreased. The mean BOND STRENGTH value in dual-cure resin cement was higher than self-cure cement. The irrigating solutions caused no significant difference in BOND STRENGTH (P=0.46). DC% had significant difference in various depths.Conclusion: According to the results of this investigation, BOND STRENGTH of dual-cure cement is higher than self-cure one in D.T Light- post because of post's translucency. 2.6% sodium hypochlorite does not affect the BOND STRENGTH.

Introduction: The aim of this in vitro study was to evaluate the effect of calcium hydroxide mixed with different vehicles on the push-out BOND STRENGTH of mineral trioxide aggregate.Materials and Methods: The study was conducted on 80 extracted single-rooted human maxillary incisor teeth who secrowns had been removed. The root canals were instrumented and divided into 4 groups according to the vehicle of the calcium hydroxide paste: Group I – distilled water; Group II – propylene glycol; Group III – 0.2% chlorhexidine; Group IV – control. After placement ofthe root canal dressings, the teeth were washed with EDTA and sodium hypochlorite and sealed with MTA. After 7 days, the push-out test was carried out using a universal testing machine. Data were analyzed with one-way ANOVA and gomes-howell tests.Results: The maximum and minimum BOND STRENGTH values were recorded in the propylene glycol and distilled water groups, respectively. There was significant differences in push out BOND STRENGTH between chlorhexidine and propylene glycol groups (P=0.015). There were significant differences in resistance to dislodgement between group control - propylene glycol (P=0.032) and group control-chlorhexidine (P=0.012).Conclusion: Placement of propylene glycol before placement of MTA in root canal improves the push-out BOND STRENGTH of this material.

Aim: The aim of this study wasto investigatethe effectofHEMA as a primingagentonshearBONDSTRENGTHof composite resin to dentin before the application of an enamelBONDing agent. Occlusal dentin of thirty six intact extracted premolars were exposed, etched and blot dried. Teeth were divided in four groups each consisted at a specimens. In group one, a mixture of 35% HEMA and acetonewas used to prime the dentine before enamel BOND. In group two, a mixture of35% HEMA and water was used as priming agent. In group threy only enamel BONDing agent was applied on dentin. In group four, scothBOND multipurposesystem was employed as BONDing agent. Shear BOND STRENGTH test was carried out one week after preparation using an instron testing machine at a ckossheasspeed of 15 mm/min. Results: The results indicated that group four exhibited significantlyless shear BOND STRENGTH than the orthers ans orther differences were not statisficaly significant. Conclusion: It was concluded that utilizing HEMA as a primingagent preceding the appliceation of enamel BOND significantly increased the shear BOND streugth of compositeresin to dentin.

Background & Aim: This study was carried out to compare the microshear BOND STRENGTH of Clearfil SE BOND between the two different regions of primary tooth: incisal and cervical.Methods & Materials: In this experimental study which was controlled in vitro trial, 20 extracted primary canines without any caries, fracture and structural anomalies were disinfected and stored in normal saline of a room temperature. Every tooth was hemisectioned buccolingually via ground section. From the two resultant mesially and distally sections, one was chosen for the test, randomly. The composite resin material (Ap-x;A2) was placed and packed into the micro bore tygon tubing with the height of 1mm and internal diameter of 0.7 mm. After application of self - etching primer (according to the manufacturers' instructions) over the incisal and cervical (buccal aspect) dentin, tygon tubes containing composite, were placed over these areas and cured for 40". Microshear BOND STRENGTH was determined using the microshear machine and also mode of failure was investigated by stereomicroscope in addition. From incisal and cervical regions of primary canines, two specimens were chosen randomly to investigate the dentinal tubules orientation in these regions by SEM.Results: SEM observations revealed that the dentinal tubules were oblique, both in incisal and cervical, so there was no difference in dentinal tubules orientation between these two regions. Mean microshear BOND STRENGTH was 33.88±1:10.67 MPa for incisal and 28.79±11.72 Mpa for cervical region. Adhesive failure was the most predominant mode of failures being observed in both regions.Conclusion: There was no statistically significant difference in microshear BOND STRENGTH of Clearfil SE BOND between the incisal and cervical dentin in primary tooth.