[Reliability and validity of the Persian version of dental student learning education questionnaire and a researcher made questionnaire about interest of dental students in their field of study]

Improving the quality of dental education significantly enhances the quality of services and promotes public health. The purpose of this study was to assess the reliability and validity of the Persian version of dental student learning education questionnaire [DSLES] and a researcher made questionnaire about interest of dental students in their field of study. A questionnaire composed of two major components was designed for this study. The first part, was a researcher made questionnaire related to students' interest in their field of study and the second part was the Persian translation of the DSLES. Delphi approach was used for content validation. Cronbach's Alpha and the Kappa coefficients were determined by SPSS for assessing reliability. All indicators of content validity [except for 6 items in the second part] and the inter-rater agreement were higher than %75. The Cronbach's alpha for all subscales was higher than %75 and the Kappa for all items was higher than%73. According to the results of 375 questionnaires, Cronbach's alpha for the first part was 79% for the second part was 85% and for the entire questionnaire was 86%. The designed questionnaire can serve as an acceptable instrument in the Iranian educational settings

[Effect of solvent removal on microtensile bond strength of etch and rinse systems under vigorous application to wet and dry dentin]

Adhesive systems are commonly used for restorative dental procedures. Solvent removal may be effective for increasing the microtensile bond strength of etch and rinse systems to dentin. The aim of this study was to evaluate the effect of solvent removal on microtensile bond strength of etch and rinse systems to wet and dry dentin. This in-vitro study was conducted on 40 intact human extracted third molars. A flat superficial dentin surface was exposed by wet abrasion. The specimens were randomly assigned to five groups. Two coats of the solvent-based [SB] and solvent-free [SF] adhesives were applied to dry [D] or rewetted [W] surfaces, under vigorous rubbing action after phosphoric acid etching according to the manufacturer's instructions. The examined groups included: group one: adhesive with solvent on dry dentin, group two: adhesive without solvent on dry dentin, group three: adhesive with solvent on wet dentin, group 4: adhesive without solvent on wet dentin and group 5 [control group]. After light curing [600mW/cm[2]/10 s], composite build-ups were constructed incrementally and specimens were stored in water [37[degree sign]C/24 h]. They were longitudinally sectioned in the "x" and "y" directions to obtain bonded sticks [1mm[2]] for immediate testing at a crosshead speed of 1 mm/min. The resultant bond strength was expressed for different fracture patterns. The microshear bond strength test was carried out in a Universal Testing Machine. The data were analyzed using two-way ANOVA. All statistical analyses were performed using SPSS version 2 software. P<0.05 was considered significant. The highest bond strength was achieved in group 1 and the lowest in group 4; but the differences among groups in this respect were not statistically significant Within the limitations of this study, the results showed that presence of solvent was not essential to achieve high bond strength values to dry and wet dentin when applied vigorously

[Microleakage evaluation of silorane-based composites versus low shirinkage methacrylate-based composites]

Determining the best restorative material to decrease microleakage in class V restorations is of great importance in operative dentistry. The aim of this in-vitro study was to evaluate the microleakage of silorane-based composites compared to low shrinkage methacrylate-based composites in class V restorations. In this in vitro study, class V cavities were prepared on the buccal and lingual surfaces of 24 human premolars and molars [48 cavities]. The specimens were divided into four groups of 6[12 cavities] as follows: group 1 [LS System Adhesive, Primer and Bond + Filtek P90], group 2 [Kalore-GC+ Clearfil SE bond], group 3 [Clearfil SE bond + Grandio] and group4 [Clearfil SE bond + Aelite LS Posterior]. All the specimens were thermocycled for 2000 cycles [5-50°C]. The teeth were then immersed in 0.5% basic fuchsin dye for 24 hours at 37°C, sectioned and observed under stereomicroscope. Data were analyzed using Kruskal-Wallis and Wilcoxon tests at a P<0.05 level of significance. There were no significant differences in microleakage among the four groups at the occlusal margin [P>0.05]. But, there were statistically significant differences in microleakage between Silorane and Aelite at the gingival margin [P<0.05]. Statistically significant differences were also found in microleakage between occlusal and gingival margins [except for Kalore and Silorane] [P>0.05] Silorane was not superior to the conventional low shrinkage methacrylate-based composites except for Aelite in terms of microleakage

Effect of sodium hypochlorite on microleakage of three-step total etch bonding systems with different solvents

some recent research have reported increased stability in mechanisms of adhesion to dentin in remove of collagen fiber of the dentin surface.The aim of this study was to evaluate the effect of sodium hypochlorite in microleakage of three step total etch dental adhesives with different solvents. this experimental study on 80 intact bovine incisor teeth, were prepared class V cavities on buccal surface of teeth, box shap and all walls on enamel. Then the specimens were randomly divided into eight groups [n=10]. NaOCl+etching+ SBMP [waterbase], NaOCl+etching+ All Bond[2] [Acetonebase], etching+ NaOCl+ SBMP, etching+ NaOCl+ All Bond[2], NaOCl+ SBMP, NaOCl+ All Bond[2], etching+ SBMP, etching+ All Bond[2]. Then the cavities were restored using Z[250] [3M] composite and Coltolux 75 light curing unit [350 mw/cm2]. The specimens were thermo cycled for 1000 times on water baths of 5 and 55[Oc]. After thermocycling, the specimens were immersed in a 2% aqueous solutions of basic fuchsin for 24 hours, then longitudinal section of each restoration was obtained and examined with a stereomicroscope for evaluation of micro leakage. The data were analyzed using kruskal-walls test and the mean of micro leakage of samples were compared by two- way ANOVA test. The findings showed that the higher rate of micro leakage was detected in hypo+Acid and lower rate of micro leakage was detected in Acid+hypo in different treatment method. The finding was different in hypo+Acid procedure, the higher rate of micro leakage was in SBMP. In hypo groups, the microleakage with ALL Bond 2 was higher than SBMP. In control groups, the microleakage with SBMP was higher than ALL Bond 2. Application of Naoci before dentin etching for removal organic materials increase the rate of microleakage of All Bondz, SBMP to that of control group

[ effect of different bonding agent curing times on microleakage of composite restorations in enamel and dentin margins using two curing systems]

Lack of appropriate seal is one of the major problems in composite restorations. Properties of the bonding system can play a crucial role in sealing ability of these restorations. The aim of this study was to evaluate the microleakage of composite restorations with varying irradiation time for curing dentin bonding agents with two different curing devices in class V cavities. In this experimental study, 60 intact extracted human molars and premolars were subjected to standard class V cavity preparations. Cavities were divided to six groups. Following etching, Excite bonding agent was applied and light cured using QTH and LED systems for 20, 30 and 40 seconds and cavities were filled with composite. The filled cavities were subjected to 3000 thermal cycles with 5-55 degree temperatures. Teeth were immersed into 0.5% basic fushin dye and sectioned occlusogingivally from the restoration middle area and the microleakage was determined using stereomicroscope by a 5-scaled rankings. Data were analyzed by Mann-Whitney and Kruskal-Wallis tests with p<.0.05 as the level of significance. No leakage was found in enamel margins. The type of light curing device did not have any significant effect on dentin margins microleakage [p>0.05]. Furthermore, no significant reduction in microleakage scores were observed in the restorations irradiated with different curing times [p>0.05]. QTH and LED curing units in 20, 30, and 40 s curing time did not have any significant effect on microleakage of class V composite restoration margins

[Effect of mechanical load cycling on class V glass- ionomer and composite restorations; a microleakage and scanning electron microscopic evaluation]

Microleakage is an important problem with direct restorations and familiarity with its contributing factors is of utmost importance. The aim of this study was scanning electron microscopic evaluation of marginal integrity in three types of class V tooth-colored restorations and the effect of load cycling on their microleakage. In this in vitro study, class V cavity preparations were made on the buccal and lingual surfaces of 30 bovine incisors [60 cavities]. The specimens were divided into three groups [n=10 each or 20 cavities] and restored as follows: group 1: with Filtek Z350[nanocomposite], group 2: Fuji IX/G Coat Plus[CGIC], and group 3: Fuji II LC[RMGI]. All specimens were finished and polished immediately and were thermocycled [_2000,5-50 °C]. In each group, half of the teeth were load cycled .Epoxy resin replicas of 12 specimens were evaluated under FE-SEM and interfacial gaps were measured. Finally the teeth were immersed in 0.5% basic fuchsine dye for 24 hours at room temperature, sectioned and observed under stereomicroscope. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests and a comparison between incisal and cervical microleakage was made with Wilcoxon test. It was shown that the mechanical load cycling caused a statistically significant increase in cervical microleakage of Fuji IX and Fuji II LC and in incisal microleakage of Fuji II LC. Microleakage in Z350 with load-cycling and Fuji IX with and without load-cycling was significantly higher in cervical compared with incisal area. Both incisal and cervical microleakage were significantly different among these materials under load-cycling.[Fuji II LC>Fuji IX>Z350]. It was concluded that the marginal sealing ability of Fuji IX under loadcycling was better than that of Fuji II LC. Z350 showed better marginal integrity while being load-cycled than both Fuji II LC and Fuji IX

[Laboratory assessment of fracture resistance of endodontically treated teeth restored with three different post and core systems]

Prefabricated posts are advantageous in restoring endodontically treated teeth because of their lower cost and operation time. Since selecting a suitable restoration is important in the survival of these teeth, in this study fracture resistance and the mode of failure of endodontically treated teeth restored with three different post and core systems were evaluated. In this in vitro study, 36 human premolars were divided into three groups; namely, group 1, non precious cast post and core; group 2, prefabricated metal post with amalgam core; group 3, FRC post and composite core. All groups received crowning. Specimens were thermocycled and loaded until definite failure. The fracture resistance and failure modes were analyzed with one way ANOVA and Fisher Exact tests. The mean failure load for the three groups was 794, 647 and 724 N, respectively. Statistical analysis did not show any significant differences between the fracture resistance of the three experimental groups [P=0.0579]. All failures in group 1, eight in group 2 and three in group 3, were unrestorable. Fisher's Exact test showed significant difference between group 3 and the two other groups [P<0.05]. If there is a 2-mm ferrule, the type of post and core does not have a significant effect on the fracture resistance, but it has a significant effect on the failure mode

[In vitro evaluation of Fuji IX glass ionomer to microleakage after exposure to hydrogen peroxide 35% in class V restoration]

Fuji IX packable glass ionomer has anti-carious properties by adhesion to tooth structure. It seems to provide adequate seal between tooth structure and restoration due to the development of ionic crosslinks. Furthermore, bleaching may affect the marginal seal of restorations, subsequently increasing the leakage of oral fluids and bacteria into the restored structure. The aim was to evaluate the effect of packable glass ionomer [Fuji IX] on the microleakage of Class V restoration exposed with and without H2O2 35%. Forty sound human molars and premolars were selected and class V standard cavities were prepared on each tooth. The specimens were assigned in two case and control groups while cases were exposed to H2O2 35% for the subsequent 5 days [30 minutes each day thrice] and the controls were stored in serum physiology. The specimens were thermocycled, stained with fushin and sectioned longitudinally. The microleakage scores were determined and subjected to Mann-Whitney U and Friedman tests in both groups. The mean and median of leakage scores in four regions of control specimens were 1.588 and 1.625 while the ratios were 1.913 and 2.25 for the teeth exposed to H2O2. The teeth exposed to H2O2 35% leaked higher than control specimens in the mesial region [p<0.04], while no significant differences were observed between two groups in the other areas. The use of Fuji IX glass ionomer cements in the restoration of class V cavities is an acceptable treatment modality for the restoration of bleached teeth

Influence of surface treatment on microtensile bond strength of self-adhesive resin cement to zirconia

Different alternative surface treatments, which have not been fully investigated, have been suggested to improve bonding to zirconia. The aim of this study was to compare microtensile bond strength of self-adhesive resin luting cements to zirconia following different surface treatments., Three blocks of zirconia [Cercon, Degussa, Germany] and three composite blocks [Z100, 3M, ESPE, USA] with 11x11x5 mm dimension were made. The blocks were divided into three groups. The ceramic blocks were cemented to the composite blocks using G-Cem [GC, Japan] according to the manufacturer's specifications. All samples were stored in 37°C distilled water for 24 hours and later sectioned in two axes using diamond disk to obtain bar shape specimens with a cross-sectional area of approximately 1mm[2] and 10mm long [n=12]. Specimens were stored in 37°C distilled water for 72 hours and thermocycled for 2000 cycles [5°C/55°C]. Each specimen was then attached to a microtensile test device. Bond strength was measured with crosshead speed of Imm/min. Failure modes were examined under stereomicroscope [x40]. Representative specimens were observed by scanning electron microscopy [SEM]. Bond strength data were analyzed with one way ANOVA and Tukey tests [a-0.05]. Alloy Primer subgroup [49.64 +/- 7.02] had a significantly higher bond strength than silane [42.12 +/- 4.2] and silicoating with silanopen [21.78 +/- 4.7] [p<0.0001]. Silanopen had the lowest bond strength in this group. SEM observation indicate that ceramic surface in silanopen group had fewer irregularities. Primers containing MDP functional monomer like Alloy Primer affect the durability of self adhesive resin cement [G-Cem] bond strength to zirconia

[ effect of incorporation of different concentrations of ethanol as a solvent on the microshear bond strength of a solvent-free dentin bonding agent]

Different studies have demonstrated that resin penetration into collagen fibers is influenced and promoted by the presence of a solvent in the bonding agents, but in order to create a reliable bond, it should be removed before curing. This study investigates the effect of adding ethanol as a solvent on the microshear bond strength of a solvent-free dentin bonding agent. After removing the occlusal enamel of 20 caries-free human third molars, midcoronal dentin slices, each about 2 mm thick were prepared then polished by slicion paper. The superficial dentin surfaces were randomly distributed into four groups and treated with James-2 containing different concentrations of ethanol [0, 5, 10, and 20 wt%] in two layers and then light-cured. The micro shear bond strength [micro SBS] was testes using a universal testing machine. The data were finally subjected to one-way ANOVA followed by Tukey's post-hoc test. James-2 containing 5 wt% ethanol provided the highest micro-shear bond strength [32.1 +/- 6.69 MPa]. There were no statistical differences in micro SBS values between other groups [25 +/- 5.8 MPa, 24.8 +/- 4.93 MPa and 21.8 +/- 4.51 MPa, respectively]. Adding ethanol as a solvent resulted in increased micro shear bond strength to dentin. At higher solvent concentrations no significant change was observed indicating that the solvents may not have been completely removed leading to poor polymerization and porosity reflected as lower bond strengths

Effect of the thermal and mechanical load cycling on microleakage of packable composite resin

Some studies have reported packable composite has good mechanical properties including less stress, polymerization shrinkage and lower coefficient in thermal expansion, but it's adaptation to cavity walls is not so good. This study evaluated the thermal cycling and Mechanical loading on microleakage of packable composite using in-vitro method. Forty eight bovine incisors were selected; Cl II cavity preparations were performed. The teeth were etched with 37% phosphoric acid. After etching, the teeth were rinsed with distilled water and dried with cotton pellet. Single bond [3M] adhesive system was applied next according to the manufacturer's instructions. The surface was light-cured [Intensity 520 MW/cm[2] and the cavities were filled with P 60 composite [3M]. The teeth were randomly divided into two groups and two subgroups [n=12]. Each group was treated with different thermal and mechanical load cycling. The entire surface of each tooth was coated with three layers of Nail polish, except for the 1- mm width around the cervical margin. The teeth were immersed in 2% fushin solution for two hours and then embedded in acrylic resin. Then they were hemi-sectioned longitudinally in a mesio-distal direction through the center of the restoration. The half tooth specimens were evaluated according to the amount of dye microleakage by means of a 40xmagnification. Statistical analysis was conducted using SPSS software, and Kruskal-Wallis test. No significant difference was detected between the four groups [P>0.05]. According to the results of this study, thermo cycling and mechanical loading showed no effect on microleakage

[Effect of curing time and application of one bottle bonding on shear bond strength of composite to dentin]

Bonding type and curing time may affect shear bond strength of composite to dentin. This study was conducted to evaluate the effect of these factors on composite to dentin bond strength. The buccal dentin of seventy-two intact extracted premolar and molar teeth were etched with phosphoric acid 37% for 5 seconds [S] and washed with water, for 15S and dried for 2-3S. The teeth were randomly assigned to six groups. Group 1: Dentin Bonding [DB] was applied once and not cured; Group 2: DB was applied once and cured for 10S; Group 3: DB was applied once and cured for 20S; Group 4: DB was applied twice and not cured; Group 5: DB was applied twice and each layer cured for 10S; Group 6: DB was applied twice and each layer was cured for 20S. Then composite blocks were placed on bonded surfaces and cured for 40S. The specimens were thermo-cycled and the shear bond strength was measured using Instron testing machine. The data were analyzed with two-way ANOVA and Tukey HSD tests. Mean shear bond strengths of the groups in MPa were as follows: Group 1: 15.57; Group 2: 16.22; Group 3: 16.68; Group 4: 17.39; Group 5: 18.18 and Group 6: 20.02. [P<0.001] Additionally the mean bond strength of groups cured 20S was significantly higher than other groups [P<0.05]. Adequate polymerization time and increased adhesive layer thickness could improve bond strength of composite to dentin

[Antiviral effects of different sterilization and disinfection methods on internal tubes of dental handpiece]

Dental handpieces are the most commonly used instruments in dentistry and their cross contamination is very high due to their direct contact with blood and saliva. The purpose of this study was to evaluate the antiviral effects of formalin tablets and autoclave on internal lumens of dental handpieces. This experimental study was designed in order to evaluate the effect of different materials and methods of sterilization and disinfection on virus elimination from internal spaces and interior chambers of dental turbines. Four study groups were composed of: 1] Vacuum autoclave, 2] Non vacuum autoclave, 3] Ten Para Formaldehyde tablets, and 4] Twenty Para Formaldehyde tablets. Nine turbines were tested in each group after preliminary washing, drying and autoclaving. The internal tubes and spaces were then contaminated with Polio and Herpes Simplex virus type I. Antiviral agents and devices were used according to the manufacturers' instructions. Two cell culture samples were obtained from each handpiece, after washing them with sterile distilled water and MEM [Minimum Essential Medium]. In each group one handpiece was designated as control. The culture results were recorded after one week. Autoclaving was perfectly effective on both Polio and Herpes Simplex virus type I in all groups [vacuumed, non-vacuumed, with or without lubricant]. Formalin tablets were 100% effective only on polio virus, and in the 20 tablet group turbines without lubricant. These tablets killed the Herpes Simplex virus in all groups. According to the results of this study, autoclaving is the best method of virus elimination in dental handpiece

[Color stability of dental composite materials after exposure to staining solutions: a spectrophotometer analysis]

The success rate of composite restorative materials depends very much on their color stability in the oral cavity. The purpose of this study was to investigate the color changes of four different brands of dental composite resin materials by using four staining solutions. A total of 128 disk-shaped specimens of 15-2 mm were prepared out of 4 composite resin materials. Two nanocomposites: Filtek supreme, Tetric Evoceram and two micro hybrid composites: Filtek Z250 and Tetric ceram, were prepared. The specimens were then divided into 4 groups of 8 specimens each and they were immersed in 4 staining solutions [Coffee, Tea, Cola, and Artificial Saliva] for 3 hours daily over a 24 day testing period. The color of specimens was measured with a spectrophotometer using CIELab color space relative to illuminant D65 at baseline and after staining. The color differences [delta E] were calculated. The delta E=3.3 was used as an acceptable value in subjective visual evaluations. Data was analyzed using ANOVA and Post-hoc test at significance level of 0.05. All tested materials showed unacceptable color change in coffee and tea groups [delta E>3.3]. The greatest color change was observed in Filtek supreme in coffee. The specimens in cola and artificial saliva didn't cause a notable color change clinically. Coffee and tea can significantly influence the discoloration of dental resin composite materials under investigation. The nanocomposite Filtek supreme color change was significantly more than other composites when exposed to coffee. Therefore, color stability of composite restorative materials depends very much on dietary habits

[EDTA dentin conditioning and Micro-shear bond strength using SE and SEM]

The main objective of using adhesive material is the improvement of restorative materials bonding to dentin surface in clean environment. The aim of this study was to investigate the effect of EDTA on bond strength of composite resin to dentin surface when used at different times and concentrations prior to application of adhesive systems by employing Scanning Electronic Microscope [SEM]. A total of 100 dentin samples were prepared from 50 human premolars. These samples were divided into two groups according to bonding type [Clearfil SE Bond =group I, Futurbond NR=group II] and each one was classified 5 subgroups according to time and concentration of EDTA as follows: 1 - Control. 2- EDTA 15%, 30 seconds. 3 - EDTA 15%, 60 seconds. 4 - EDTA 24%, 30 seconds. 5 - EDTA 24%, 60 seconds. These samples were conditioned and composite cylinders were adhered to them. After 500 cycles of thermocycling, the testing for micro-shear bond strength was conducted on these samples. Another 10 samples were demineralized for 30 seconds with 6NHCL and deproteinized with 2.5% Naocl for 10 minutes, air dried with desiccators and viewed under SEM. Data were analyzed using one-way as well as three-way ANOVA and Tukey tests. The mean Micro-shear bond strength in group I [Clearfil SE bond] were: 31.88 [ +/- 13] for subgroup 1, 28.4 [ +/- 13] in subgroup 2, 29.8 [ +/- 9] in subgroup 3, 29.2 [ +/- 11] in subgroup 4, and 32.7 [ +/- 12] in subgroup 5. The mean Micro-shear bond strength in group 2 [Futurbond NR]: were: 22.6 [ +/- 10] for subgroup 1, 28.5 [ +/- 9] in subgroup 2, 27.3 [ +/- 10] subgroup 3, 32.4 [ +/- 15] in subgroup 4, and 31.1 [ +/- 14] in subgroup 5. There were no significant differences between the samples conditioned and the ones not conditioned with EDTA, time and the concentration of EDTA applied and also the two bonding types. EDTA conditioning prior to use of the two bonding agents under investigation in this study did not improve the bonding strength of the self etch systems, neither did the time and the concentration of EDTA applied

Postoperative thermal sensitivity reduction after amalgam fillings; A clinical evaluation and presentation of a new method

Prepared cavities are usually treated with liners prior to amalgam placement. Light cured glass ionomer [RMGI] have been widely used for this purpose. The aim of this study was to compare the effect of RMGI on decreasing postoperative sensitivity with a new method of applying self etch bonding and glass ionomer simultaneously. In a blind randomized clinical trial study, A total of 36 patients with 2 deep caries in their posterior teeth [cavities with less than 2 mm distance from pulp in radiography] were included. Diagnostic tests [cold-heat, percussion, electric pulp test] were performed for each tooth prior to final restoration. After cavity preparation, one tooth was treated by light cured glass ionomer, the next one with SE bond and glass ionomer randomly, followed by amalgam restoration. Diagnostic tests were performed three days, thirty days and three months after amalgam restoration. The statistical analysis was performed using SPSS software version 11.5 as well as Friedman and Wilcoxon signed-rank tests. In second follow up, the sensitivity to cold was significantly less than the conventional method [P < 0.05] in our suggested compound method. However, there was no significant difference between the two groups when using the other vitality tests. Using SE bond and light cured glass ionomer simultaneously was an effective new method of decreasing the postoperative sensitivity in short term, [1 month] although, there was no difference between the two groups in the long term

Effect of saliva and blood contamination on shear bond strength of cured dentin adhesives

Achieving good moisture control is a common problem encountered in restorative dentistry, especially after applying and curing dentin bonding agents over dentin tissue. The aim of this study was evaluation of the effect of saliva and blood contamination on shear bond strength of cured dentin adhesives. Thirty-five extracted sound human molars and premolars were collected and after debridement, stored in 0.5% chloramine solution for one week and preserved in distilled water, afterwards. The buccal and lingual surfaces were ground flat to expose the dentin. These surfaces were etched with 37% phosphoric acid for [5 seconds, rinsed for 20 seconds and dried with a cotton pellet. A single-bottle dentin-bonding agent was applied on the etched surfaces and cured for 20 seconds. This procedure was repeated in order to achieve excellent bonding. The specimens were divided into five groups of 7 each: Group 1 [Control] was not contaminated; in Group 2, bonding surfaces were contaminated with blood and saliva without any other treatment; Group 3 was contaminated and then rinsed and dried completely; Group 4 was contaminated, then rinsed and dried and re-etched for IC seconds; Group 5 was contaminated, rinsed and completely dried, re-etched for 10 seconds, rinsed, dried, re-bonded and cured for 20 seconds. A composite cylinder built in a plastic mold [2 mm high < 10 mm wide] was placed on the treated surfaces and cured for 40 seconds. After thermocycling, the shear bond strengths of all specimens were measured using an Instron testing machine. The data were subjected to one-way ANOVA, with 95% coefficient of confidence. A significant difference was observed between the mean shear bond strength of the contaminated and uncontaminated groups [P=<0.001]. Contamination of cured dentin bonding agents with blood and saliva, significantly reduced the shear bond strength of composite to dentin

Effect of phosphoric acid on the self etching primer bond strength and its relation on oral health status

Self etching primers, due to ease of manipulation, have been extensively used in recent years. These self etching primers containing a relatively weak acid, may not provide an optimal bond strength. The purpose of the present in-vitro investigation was to evaluate the effects of 37% phosphoric acid application prior to applying self etching primers on composite bond strength. In this experimental study a total of 48 premolar and molar teeth, free of caries, filling, abrasion, crack or other dental defects were selected. The extracted teeth were immediately stored in physiologic serum and divided randomly into two equal groups [n=24].Each group was also divided into two subgroups of twelve teeth each as follows: Subgroup A: enamel was not acid-etched, subgroup B: enamel was acid-etched [group I].Subgroup C: dentin was not acid- etched, subgroup D: dentin was acid-etched [group II].In acid-conditioned groups, water rinsing was followed by the application of a bonding agent [Etch and Primer 3], however for non-acid-treated groups, just the bonding agent was used. Then composite resin blocks [1.5'2 mm and 2.5 mm in diameter] were formed and light cured at all directions for 40 seconds, following this the specimens were placed in an Instron universal testing machine to determine shear bond strength. The data were analyzed by t-test. Results showed that no statistically significant differences were between the mean values of etch and un-etch enamel [P=0.232], similarly those of etch and un-etch dentin [P=0.148]. In this investigation we concluded that acidic components employed in self-etching primers were of weak type, but self-etching primers could be used without phosphoric acid conditioning

Comparison of shear bond strength between composite resin and porcelain using different bonding systems

Ceramics as in ceramo-metallic and all ceramic tooth restorations have grown popular owing to their high tissue compatibility and esthetic advantages. Such restorations have the capability to deliver valuable services over a long period of time; however, failures under intraoral conditions are not unanticipated. The purpose of this in-vitro study was to investigate the shear bond strength of composite resin to porcelain using different bonding system materials.In this experimental study forty porcelain blocks were prepared and randomly divided into four equal groups. The porcelain surfaces were then etched with HF for 2 minutes, washed with water for 2 minutes and treated with a silane layer. The silane treated porcelain surfaces were left for one minute and then the specimens were bonded to composite resin as follow: Group 1 [control group], hybrid composite Z100 was applied and light cured from four directions for 20 seconds. Group 2, flowable composite was applied and light cured for 20 seconds. Group 3, unfilled resin was used and photo cured for 20 seconds. Group 4, [Dentin bonding agent] adhesive resin was used followed by 20 seconds photo curing. Hybrid composite resin Z100 was subsequently applied on all porcelain surfaces of groups 2, 3 and 4, and light cured for 20 seconds from four directions. Specimens were then subjected to thermocycling 1000 times. Shear bond strength was determined by a Universal testing machine. The data obtained was subjected to a one-way ANOVA test.The results indicate that there is a statistically significant difference between adhesive group and the other three groups of hybrid, flowable and unfilled resin [P<0.05]. The results from this study showed that the shear bond strength of composite resin to porcelain was significantly higher for porcelain bonded surfaces using a dentin bonding agent than that of other materials tested

Comparison of BOP and PPD indices in restored posterior teeth with composite. P60 [3M] and natural [intact] teeth

Composite Resin is a kind of polymer that has been recently substituted for Amalgam; therefore biocompatibility of Composite with periodontal tissue should be acceptable and also should not clinically induce inflammation and irritation symptoms in gingival tissue over a long time. The objective of this research is to investigate biocompatibility of posterior composite with periodontal tissue by means of PPD and BOP indices in teeth which have been filled with Composite and intact ones. This is a clinical trial research and a kind of case control in which 40 teeth of 20 patients -15 men and 5 women - were selected from students of Dentistry Faculty of Tehran Medical Science University as the case group with cl II caries in posterior teeth [4,5,6,7] and the outline of preparation was near or 0.5 coronal to gingival which were filled with posterior composite Resin [P60]. PPD indices based on ranking of 1 to 4 and BOP based on Muhlemann category were measured and recorded exactly before operation and 3 and 6 months after in 40 restored case group and 40 control group [intact teeth in opposite quadrant]. Then the results were analyzed by means of SPSS software and tested by Friedman and Wilcoxon Tests. There was no significant difference between BOP Indices in To-Ti and T[2] in case group and also in control group. Further more there was no significant difference in PPD Indices in To-Ti and T; in case and control groups. There was no significant difference between BOP indices in case and control teeth groups in To [exactly before operation]. Also there was no significant difference between mentioned teeth groups in Tl [3 months after operation]. But a significant difference was found between them in T2 [6months after operation] [P=0. 035] Furthermore there was no difference between PPD indices in case and control teeth groups in proximal side of buccal surface in To, Tl and T2 and also no significant difference on the proximal side of lingual surface in To, Tl and T2. Regarding biocompatibility of new generation posterior Composite Resin [like P60] with periodontal tissue, they have not been able to compete with the intact surface of tooth