Statement of Problem: Composite reins have recently become popular for posterior teeth restorations.Gap formation and subsequent microleakage are of the complications resulting from such restorations.One of the techniques to overcome polymerization shrinkage of composite resins is sandwich technique (application of glass ionomer as a base beneath the composite resin). Since polymerization patterns in two types of composite resins (light CURE and SELF CURE) differ from each other, various effects on the bond strength between glass ionomer and dentin are expected.Purpose: The aim of this in vitro study was to evaluate the effects of SELF- CURE and light- CURE composite resins in sandwich technique on the bond strength of light CURE glass ionomer and dentin.Materials and Methods: 40 extracted human premolars were selected and divided into four groups:Group 1: Light CURE glass ionomer of 1mm thickness was placed on dentin.Group 2: 1mm thickness of light CURE glass ionomer plus a mass of SELF CURE composite resin of 2mm thickness were placed.Group 3: 1mm thickness of light CURE glass ionomer plus light CURE composite resin as two separate 1mm layer were placed.Group 4: 1mm thickness of light CURE glass ionomer with 37% phosphoric acid etching followed by two separate layers of light CURE composite resin of 1mm thickness were placed.SEM was used to determine gap size at GI- dentin and GI- composite interfaces. The findings were analyzed by ANOVA and t-student tests.Results: Groups 1 and 2 showed no gap at GI-dentin interface and also cracks were not observed in all these specimens. In group 3, there was gap between light CURE GI and light CURE composite resin and cracks were seen in GI, too. Group 4 showed gap at both interfaces and more cracks were seen in GI. Groups 1 and 2 showed the least gap formation and group 4 showed the most. Statistically significant difference was found between groups 3, 4 and group 1 (control), 2.Conclusion: Base on this study, the application of SELF-CURE composite resin on light CURE GI showed no gap and crack formation on GI-dentin and GI-composite interfaces and GI itSELF. However, light CURE composite resins and glass ionomer etching aggregated crack and gap formation.

Background and aim: Inadequate bond strength of resin cements to dentin appears to be a typical cause of failure in retention of fiber posts. In restoring endodontically treated teeth with fiber posts the cement-dentin interface is the weakest link. This study aims to compare the effect of SELF-etch and SELF-ADHESIVE resin cements on shear bond strength of fiber posts to dentin.Materials and methods: This in vitro experimental study included 40 mandibular premolars with a single canal. All samples received standardized endodontic treatment after meeting the inclusion criteria. They were randomly divided into four groups and a post space was prepared in each sample. A size two Match post RTD fiber post was cemented into each sample using CoreCem (RTD) in group A, Panavia F2 (Kuraray) in group B, Bis Cem (Bisco) in group C and Maxcem Elite (Kerr) in group D as cementing agents. All samples were then cut into two pieces. Each specimen was loaded with equal force using a Universal Testing Machine. The load was applied from the apical to the coronal portion of each sample until fracture occurred. The mean shear bond strength for two each group was recorded and statistically analyzed with ANOVA (one way) and Dunnett’s tests using SPSS.Results: The mean shear bond strength was found to be as follows: Group A: (12.66 ±3.77) MPa Group B: (14.61±4.18) MPa Group C: (7.26±2.49) MPa Group D: (6.68±3.17) Mpa, Significant difference was demonstrated between shear bond strength of four groups (P=0.001). Mean bond strengths of resin cements in group A and B were not statistically different. Same results were shown when comparing cements in group C and D. However, cements in group A and B (SELF-etch) provided stronger bonds to dentin compared to group C and D (SELF-ADHESIVE), the difference being statistically significant (P<0.05).Conclusion: The use of SELF-etch resin cements results in higher shear bond strength to dentin compared to SELF-ADHESIVE resin cements.

Background and purpose: In orthodontic brackets, unlike restorative materials or porcelain, the shear bond strength of the ADHESIVEs used is important because the oblique forces from food or objects or the tension of the ADHESIVE food affect the brackets. This study aimed at measuring and comparing shear bond strength and ADHESIVE remnant index of light CURE composite, no mix (SELF-CURE) composite, and no bond composite (GC Orthoconnect). Materials and methods: A total of 27 non-carious and sound human premolar teeth were used. The samples were divided into three groups, including light CURE composite, SELF-CURE composite, and no bond composite (GC Orthoconnect). After bonding and thermocycling process, the metal brackets (American Orthodontics) were then debonded using universal testing machine. ADHESIVE remnant index (ARI) score was assessed. Results: The highest and lowest SBS mean values were seen in SELF-CURE group (18. 0402±, 5. 71665) and light CURE group (7. 7890±, 3. 98995), respectively. There were significant differences in SBS values between all groups except between the no bond group and the SELF-CURE group (P= 0. 18, P>0. 05). The highest ARI scores were 0 in the SELF-CURE group and 3 in the no bond group and the light CURE group. Conclusion: The no bond composite provided acceptable overall shear bond strength and compared to light CURE composite showed higher shear bond strength and lower bond failure.

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.

Objective: The aim of this study was to evaluate the bond strength of SELF- etch ADHESIVE system (AdheSE) with three dentin conditioning methods.Materials and Method: Sixty six human intact premolar was divided into 3 group (n=22), a flat dentin surface was made. In group 1: The tooth was etched by phosphoric acid (%35), then bonding material of AdheSE was used. In group 2: only bonding material was used. In group 3: The procedure was as the first group, but after etching, the tooth surface was deproteinized by Naocl (%5). Then with a cylindrical composite model were made. Thermolcycling was performed using 500 cycles, and subjected to a blade (cross head) with the speed of 0.5 mm/min .Collected data was analyzed using 1 way ANOVA test in addition to a Duncan test.Results: Results revealed that hypochlorite sodium (Naocl) decreased the bond strength. When acid phosphoric and then dentin bonding agent were used, mean bond strength (25.72 MPa) was the most. Excess etching increases the bond strength.Conclusion: When the SELF etching ADHESIVEs are used for repair of teeth, excess etching increases the bond strength.

Background and Aim: The bonding mechanisms of SELF etching primers, based upon the simultaneous etching and priming of dentin, simplifies the bonding technique, but the efficiency of these systems is still controversial. This study compared the shear bond strength of three SELF etch ADHESIVE systems in dry and wet conditions. Materials and Method: In this experimental study, 77 intact bovine lower incisors with flat 600 grit sanded enamel surface were fixed in acrylic molds and divided into 7 groups, of 11 teeth. The enamel surfaces were treated according to a special procedure as follows: Group 1: Prompt L-Pop (PLP) in dry condition, Group 2: Prompt L-Pop in wet condition, Group 3: Clearfield SE Bond (CSEB) in dry condition, Group 4: Clearfield SE Bond in wet condition, Group 5: iBond (iB) in dry condition, Group 6: iBond in wet condition, Group 7: Margin Bond (Control) in dry condition. Surfaces were air dried for ten seconds, or blot dried in wet condition. Composite resin was bonded on the enamel and built up by applying a cylindric teflon split mold (4 mm height 2mm diameter). After 24 hours storage in dionized water at room temperature, all specimens were thermocycled and shear bond test was employed by a universal testing machine (Instron) with a cross-head speed of 1mm/min. The shear bond strength was recorded in MPa and data were analyzed with ANOVA and Scheffe statistical tests. P<0.05 was considered as statistically significant. The mode of failure was examined under a stereomicroscope. Results: 1- Shear bond strength of CSEB in dry condition (21.5 ± 4.8 MPa) was significantly higher than PLP and iB groups (p<0.0001). 2- Shear bond strength of iB and PLP groups in dry condition (9.60 ± 2.2, 9.49 ± 3 MPa) were significantly lower than CSEB and control (2.99 ± 5.1 MPa) (P<0.0001). 3- There was no significant difference between PLP and iB groups in dry condition (P=1). 4- Shear bond strength of CSEB in wet condition (21.8 ± 3 MPa) was significantly higher than PLP and iB groups (P=0.0). 5- Shear bond strength of CSEB (10.8 ± 3 MPa) and PLP (10.6 ± 4 MPa) in wet condition were significantly lower than CSEB and Control groups (P=0.0). 6- There was no significant difference between PLP and iB groups in wet condition (P=0.99). 7- Shear bond strength of the three ADHESIVEs had no significant difference in dry and wet conditions (PLP: P= 0.53, CSEB: P= 0.84, iB: P= 0.53). The mode of failure in two groups of PLP and two groups of iB was predominantly in the ADHESIVE bond and in the two groups of CSEB, mixed failure (ADHESIVE with cohesive in composite) was predominantly observed. Conclusion: CSEB had higher while iB and PLP showed lower bond strength to ground enamel. The three SELF-etch ADHESIVEs in this study did not show technique sensitivity to wet and dry enamel.  

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: Oral candidiasis is the most common opportunistic infection of the oral mucosa with Candida spp. Candida species form a biofilm in patients who need orthodontics with removable plaque, and this structure can lead to Candidemia. It is important to find effective plant compounds, which have fewerside effects and are natural, to prevent biofilm formation. The aim of the present study was to determine the effect of adding Thymus vulgaris and Cinnamomum verum essential oils to SELF- CURE acrylic blocks on Candida albicans colonization. Methods: In this experimental study, the antifungal activity of essential oils of Thymus vulgaris, Cinnamomum verum and nystatin against of Candida albicans ATCC10231 was evaluated in order to determine MIC according to CLSI-M27S4 guidelines. Powder and monomer were poured into tablet molds to make SELF-CURE acrylic plaques. A total of 144 SELF- CURE acrylic plaques were divided into 24 groups of 6 in petri dish. Three groups contained powder and monomer, three groups contained nystatin drug, and 18 groups contained different concentrations of essential oils of Thymus vulgaris and Cinnamomum verum. Then, the samples were incubated in artificial saliva enriched, with Candida albicans at 37°C and the effects of essential oils of Thymus vulgaris and Cinnamomum verum on the binding of Candida albicans were reported by the cfu/ml count method. Statistical analysis of data was done using Stata-15 software. ANOVA and Tukey's test were used to confirm the results. Results: The evaluating the sensitivity of Candida albicans ATCC10231 to essential oils of Thymus vulgaris, Cinnamomum verum and Nystatin were obtained as MIC= 120µg/ml, MIC= 340µg/ml and MIC= 1µg/ml, respectively. The attachment of yeast cells to SELF- CURE acrylic blocks for Cinnamomum verum essential oil was significant in MIC= 340 µg/ml (p= 0.02), MIC= 680 µg/ml (p= 0.01) and nystatin 1 µg/ml (p= 0.00) compared to the negative control group. However, this amount was not statistically significant for Thymus vulgaris essential oil        (p= 0.14). Conclusion: Adding essential oil of Cinnamomum verum to acrylic resin prosthesis can be effective in controlling the proliferation of Candida albicans on the surface of the prosthesis. However, its effects on the physical properties of acrylic resin dentures need further studies.

Background and Aims: Micro leakage is a criterion proposed for assessing the success of any restorative material. Complete seal is difficult especially for dentin margins compared to enamel margins. The aim of this study was to assess the micro leakage at the enamel and dentin margins of class V cavities restored by two GIs and two SELF-etch ADHESIVE systems.Materials and Methods: This study was done on forty third molars. Class V cavities (3´2´2mm) were prepared on the buccal and lingual surfaces of teeth using high speed handpiece with 0.8 mm diamond fissure burr. The occlusal margins of the cavities in the enamel and gingival margins were placed 1 mm below the CEJ. The teeth were divided into 4 groups and the bondings were CUREd for 20 sec and the teeth were restored. The specimens were kept in distilled water at the temperature of 37°C for 24 hrs. The teeth were thermo cycled and cut in buccolingual direction using diamond disc under water. The dye penetration was evaluated using a stereomicroscope and the leakage was scored. The scores were compared using Kruskal-Wallis test while the paired comparisons were done using Bonferroni correction. P≤0.05 was regarded as significant results.Results: Micro leakage scores were similar at the occlusal and gingival walls of all test groups. At the gingival walls, the least micro leakage scores were observed. “Fuji IX + SE bond” group showed significant differences with the “Fuji IX + G bond” and “Nano glass + G bond” groups (P£0.05). At the occlusal walls, the least scores were observed in the “Fuji IX+SE bond” specimens which were significantly different from the other groups (P£0.05).Conclusion: SELF-CURE glass ionomers yielded less micro leakage scores compared to the different types of light-CUREs due to the less polymerization shrinkage.