Background & Aim: The purpose of this study was to evaluate the micro-SHEAR bond strength of two kinds of resin-based cements with fluoride release with the usage of five adhesive systems to enamel and dentin. Materials & methods: Bovine flat enamel or dentin surfaces were used in this study. Micro cylinders of resin cement with Xeno Cem Plus (XCP) or Panavia Fluoro Cement (PFC) were bonded to enamel or dentin as followed: XCP or PFC as instructions prior to the usage of their own adhesive systems, Xeno CF II+XCP, SE Bond+PFC, or Clearfil Liner Bond II (CLB) + PFC. After the storage in 37°c water for 24 hrs, micro-SHEAR bond test was applied for all the test groups. The data were statistically analyzed using two-way analysis of variance (ANOVA). After two-way ANOVA, one-way ANOVA and multiple comparisons with Fishers PLSD test were made.Results: Are given as follow (enamel and dentin, mean±SD in MPa); XCP, 13.7±4.0 and 15.5±9.2; PFC, 23.7±10.6 and 15.0±7.3; XCP+XCF II, 35.4±11.5 and 17.1±4.0; PFC+SE, 54.2±9.8 and 41.7±12.0; PFCCLB, 31.39±3.09 and 15.09±4.35. ANOVA (α=0.05) analyze revealed the usage of SE Bond under PFC significantly increased the bond strength to both enamel and dentin. Bonding of Xeno CFII was only improved the bonding to enamel with the application of XCP.Conclusion: Light-cure adhesive systems significantly improve the bonding of current resin cements.

Objectives: Rebonding of isolated brackets is an economic option that can be conducted using available in-office or commercial recycling methods. Nowadays, lasers are known as an efficient modality for composite REMOVAL, but there is not much information available about using lasers for REMOVAL of adhesive remnants from the ceramic bracket base. Materials and Methods: Fifty human premolar teeth were divided into five groups. Samples in all groups were bonded to ceramic brackets. Brackets in four groups were debonded and the remaining adhesive was removed by Er: YAG laser, Er; Cr: YSGG laser, sandblasting or direct flame. After removing adhesives from the tooth surfaces by carbide bur, the recycled brackets were bonded again. in the control group, new ceramic brackets were bonded. Finally, all brackets were debonded by universal testing machine and their SHEAR bond strength (SBS) was measured. The adhesive remnant index (ARI) was calculated under a stereomicroscope at x10 magnification. Data were analyzed using one-way ANOVA and Tukey’ s test. Results: SRS values showed no significant difference among the five groups (P=0. 568). The highest SRS was noted in the control group (7. 46± 1. 4 MPa), followed by Er: YAG laser group (7. 40± 1. 24 Mpa) and the lowest was noted in the flame group (6. 32± 2. 3 Mpa). ARI scores indicated that most of the adhesive remained on the tooth surface in all groups Conclusions: Recycling of ceramic brackets with Er: YAG laser is an efficient in-office method which causes the least damage to the bracket base. However, all methods of bracket recycling showed acceptable SBS.

Background and Aim: Achieving adhesion between restorative materials and dentin as a wet and dynamic surface is an important topic in restorative and especially in conservative dentistry. Adhesion of new dentin bonding systems depends on the formation of hybrid layer and micromechanical retention. Nevertheless, an ideal adhesive system has not yet been introduced recent studies reveal an increase in bonding stability when the collagen is removed from demineralized dentin surfaces. This study investigates the effect of collagen REMOVAL on the SHEAR bond strength of four single bottle dentin bonding systems regarding their structural differences. Materials and Methods: This experimental study was performed on 56 intact human premolar teeth. Smooth surfaces of dentin were prepared on buccal & lingual aspects of teeth, providing 112 dentin surfaces. The dentin surfaces were etched with 37% phosphoric acid for 15 seconds and then rinsed. The specimens were divided into 8 groups. Single bottle adhesive systems [Single Bond (3M), One-Step (Bisco), Prime & Bond NT (Dentsply), and Excite (Vivadent)] were then applied on the dentin surfaces of 4 groups using the wet bonding technique. In the other 4 groups, the demineralized dentin surfaces were treated with a 5.25% solution of sodium hypochlorite for one minute in order to remove the surface organic components. The adhesive systems mentioned before were applied to these 4 groups with the same wet bonding technique. A cylinder of Z100 (3M) dental composite with a 3 mm diameter and 2 mm height was placed on the adhesive covered dentin surface of all groups and light-cured (400 mW/cm2 ,40 sec on each side). The specimens were kept in distilled water at room temperature for one week and then thermocycled for 3000 times (5-55 °c). SHEAR bond strength of specimens was measured using an Instron (1495) universal mechanical testing machine with cross-head speed of 0.5 mm/minute and chisel form SHEARing blade. Data were analyzed by Two Way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance. Results: The mean & standard deviation of SHEAR bond strengths (in Mpa unit) of all groups were as follows: One-Step = 19.60 ±1.83            One-step +H = 19.72 ±2.01 Single Bond =21.44±3.94           Single Bond +H =18.26±2.85 Prime& Bond NT=26.51±5.02      Prime& Bond NT+H=26.98±5.70 Excite =29.78 ±3.85                   Excite +H = 19.07 ±9.94 Analysis of the results revealed that the use of 5.25% sodium hypochlorite for one minute on the surface of demineralized dentin significantly decreased the SHEAR bond strength of Excite and Single Bond (P<0.05). For Prime & Bond NT and One-Step, SHEAR bond strength increased with this treatment but was not statistically significant (p>0.05). Conclusion: Based on the results of this study, collagen REMOVAL from demineralized dentin surface caused a significant decrease in SHEAR bond strength of alcohol & water/alcohol based bonding systems, while the bonding strength of the acetone based systems was not affected. Therefore, the effect of collagen REMOVAL on SHEAR bond strength depends on the bonding system applied and its solvent type.    

Background & Aim: The goal of many researchers conducted nowadays is to achieve adhesive materials that exhibit good bonding capability, simplified application and easy handling. In this regard, self - etching primer systems were introduced to the market. The aim of this study was to evaluate the micro- SHEAR bond strength of two new self - etching materials compared to an already established bonding materials. Methods & Materials: Sections of human third molars (1.5 mm) were used in this study. The tooth surfaces were polished with 600 grit SiC paper nder running water and randomly divided into three groups. In group I Clearfil Protect Bond (Kuraray Japan), in group II, Clearfil SE Bond (Kurary Japan) as control group, and in group ill, Clearfil Tri - S Bond (KUrary Japan) were used due to manufacturer's instruction. Hollow tygon tubes (0.7×0.5mm) were placed on the enamel and dentin surfaces and Clearfil AP-X composite was inserted into the tubes. After 40 seconds light curing, the tygon tubes were removed and samples were stored in distilled water for 24 hours. Micro – SHEAR bond strength was measured (EZ-test, Shimadzu Co., Kyoto, Japan) and the data was statistically analysis by one - way ANOVA and multiple comparison with LSD.Result: Mean bond strength in enamel was 35.76±6.89 mpa in group I; 33.62±5.59 mpa in group II, and 34.65±5.65 mpa in group III. Their difference was not statically significant. Mean bond strength in dentin was 34.47±6.0 mpa in group I, 45.20±10.3 mpa in group II, and 35.99±6.13 mpa in group III. The bond strength in group II was higher than group I and II (P<0.05), and the difference between group I and II was not statistically significant.Conclusion: After 24 hours, the SHEAR bond strength of two new adhesive systems to enamel was similar to SE Bond, however, SE Bond exhibited a higher bond strength to dentine.

Background and Aim: Sodium hypochlorite can remove the organic phase of the demineralized dentin and it produces direct resin bonding with hydroxyapatite crystals. Therefore, the hydrolytic degradation of collagen fibrils which might affect the bonding durability is removed. The aim of this study was to evaluate the effect of collagen fibrils REMOVAL by 10% NaOCl on dentin SHEAR bond strength of two total etch and self-etch adhesive systems.Materials and Methods: Sixty extracted human premolar teeth were used in this study. Buccal surface of teeth were grounded until dentin was exposed. Then teeth were divided into four groups. According to dentin surface treatment, experimental groups were as follows: Group I: Single Bond (3M) according to manufacture instruction, Group II: 10% NaOCl+ Single bond (3M), Group III: Clearfil SE Bond (Kuraray) according to manufacture instruction, and Group IV: Clearfil SE Bond primer. After that, the specimens were immersed in 50% acetone solution for removing extra monomer. Then the specimens were rinsed and dried. 10% NaOCl was applied and finally adhesive was used. Then composite was bonded to the treated surfaces using a 4´2 mm cylindrical plastic mold. Specimens were thermocycled for 500 cycles (5-55oC). A SHEAR load was employed by a universal testing machine with a cross head speed of 1mm/min. The data were analyzed for statistical significance with One-way ANOVA, Two-way ANOVA and Tukey HSD post-hoc tests.Results: The mean SHEAR bond strengths of groups were as follows: Single Bond=16.8±4.2, Clearfil SE Bond=23.7±4.07, Single Bond+NaOCl=10.5±4.34, Clearfil SE Bond+NaOCl=23.3±3.65 MPa. Statistical analysis revealed that using 10% NaOCl significantly decreased the SHEAR bond strength in Single Bond group (P=0.00), but caused no significant difference in the SHEAR bond strength in Clearfil SE Bond group (P=0.99).Conclusion: Based on the results of this study, NaOCl treatment did not improve the bond strength in self-etch adhesive and caused a significant decrease in the bond strength of total etch adhesive system.

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.

Statement of Problem: There is no enough published data about the SHEAR bond strength of resin modified glass ionomer adhesives on caries-affected primary tooth dentin excavated using minimally invasive systems.Objectives: To evaluate the SHEAR bond strength of 2 different adhesives (one resin modified glass ionomer and one resin) using two caries REMOVAL techniques on healthy and caries-affected primary dentin.Materials and Methods: Two caries REMOVAL methods including mechanical (handpiece) and chemomechanical (Carisolv) techniques and two types of adhesives including one resin adhesive (Clearfil SE Bond; CSEB, Kuraray) and one resin-modified glass ionomer adhesive (Riva Bond LC; RBLC, SDI) were used in this study. Ten extracted healthy primary teeth were used for the control group. The teeth were sectioned bucco-lingually and mesio-distally in order to obtain four specimens from each tooth. Thirty suitable specimens were selected as the “control” and randomly divided into two groups of “sound dentin” based on the type of the adhesive used. Sixty extracted caries affected teeth were used for the carious group; sectioned as mentioned above and sixty suitable specimens were selected as the “treatment”. Then the specimens were arbitrarily divided into four groupsbased on caries REMOVAL techniques and the type of adhesive used (n=15). After bonding with either CSEB or RBLC, the specimenswere restored with a resin composite by means of PVC tubes and subjected to the SHEAR bond strength test. The data was analyzed using ANOVA and Tukey’s test.Results: The specimens in Carisolv group bonded with CSEB (11.68±3.1) showed a statistically significant higher mean bond strength followed by those in handpiece group bonded with CSEB (9.4±2.7), which exhibited higher mean values than those groups with RBLC (p<0.05). SHEAR bond strength values for Clearfil SE Bond was not significantly higher than Riva Bond LC when used in sound dentin.Conclusions: The lowest SHEAR bond strengths for both adhesives were observed on caries-free dentin.

Background: Since three decade ago, the application of the concept of finite element analysis (EEA) have received a keen interest among dental investigators. In practice the FEA provides detailed stress information regarding to a non-homogenious body such as craniofocal skeletal growth, tooth post ceramo-metal crowns and etc. The aim of this study was the determination of the influence of stress distribution at the cement interface of metal ceramic restoration-dentin. Materials and Methods: An idealized metal-ceramic crown model was developed. The model was divided into very small segments. Various loading conditions was applied to the model. A super sap software was used for analyzing the stress distribution. Results & Conclusion: The results of this study suggest that the higher SHEAR stress was developed in the cervical region by two dimensional methods.

Background and Aim: Considering the high failure rate of bracket bonding in orthodontics treatment, in the event of either the patient accidentally applying inappropriate forces to the bracket or poor bonding techniques, the objective of this study was to determine the effect of resin REMOVAL methods on enamel surface and SHEAR bond strength of rebonded brackets.Materials and Methods: A total of 76 fresh human premolars were used in this experimental (in vitro) study, seventy of which were divided into three experimental groups (N:20) and one control group (N:10). (Simple random sampling). After the bonding procedure in the experimental groups using No-mix composite and mesh base brackets, debonding was performed with use of plier. Buccal surface of each sample was examined by an optical microscope (×10) to determine the location of the bond failure interface, using an Adhesive Remnant Index (ARI). The remnant adhesives were cleaned up with three methods: 1- High speed-Tungsten Carbide Bur (TCB), 2- Low speed-TCB, 3- Sandblast with Microetcher. For rebounding procedure each experimental group divided into two subgroups of 10. A- With use of new bracket, B- Sandblasted bracket. Rebounding was performed on 70 samples in experimental and control groups and the second set of SBS and ARI were calculated and statistically evaluated. In six samples, the buccal surface of each tooth divided into four groups for bonding composite to observe the effect of the above interventions on the enamel structure by SEM (×1000). The data was analyzed with (One-way & Two-way) ANOVA, Dunnett t and Kruskul-Wallis.Results: No significant difference was found between control and experimental groups reading SHEAR Bond Strength (SBS) and ARI detachment levels with respect to resin cleanup methods and bracket type. (P>0.6) But SEM studies showed complete destruction of enemal surface as a result of sandblasting with micro etcher. enamel surface preservation was found to be closest to it normal morphology in TCB group.Conclusion: Enamel damage after rebounding seems to be inevitable but with TCB it can be reduced and also reasonable SBS should be achieved.