معصومه حسنی طباطبایی

Methicillin-resistant Staphylococcus Aureus (MRSA) is an important infection source in dentistry for different disinfectants to be used to prevent its transmission. Furthermore, a variety of chemical disinfectants are developed to remove bacterial infections from the dental care workers' hands and claims are made regarding their superiority in infection control, although all requires scientific investigations. The aim of present study was to compare the effects of chemical hand-disinfectants Micro Zed HD, Aseptoman and Decosept on MRSA (methicillin resistant staphylococcus aureus) in different periods of time. In this experimental study, the antibacterial efficacy of three hand-disinfectants on standard strain of MRSA (USA300: ATCC® BAA-1717™) was evaluated according to European standard of evaluating antiseptics (EN 1040:2005 CSN EN). First we prepared a 0.5 Mc Farland (108 CFU/ml) suspension of MRSA, and exposed to three disinfectants for 15, 30, 60 and 90 seconds. Then, they were transferred to separate plates of Mueller-Hinton medium and incubated in 37◦C for 24 hours. The plates were compared then with control plate to evaluate the efficacy of materials on bacteria by calculating the CFU/ml of plates. Three hand-disinfectants evaluated in this study had the maximum anticabterial effect on MRSA in the minimum time of exposure (15 seconds), and we found no trace of growth in any plates. The three hand-disinfectans (MicroZed HD, Aseptoman and Decosept) in the concentration suggested by their companies, showed no difference in efficacy to remove MRSA from hands.

Color is the most important and complicated part of aesthetic dentistry. The tooth color matching of restorations is considered as one of the most difficult tasks in the restorative dentistry. The aim of this study to evaluate the effect of two training methods on the dental students’ ability in determining tooth color matching. In this study, 40 dentistry students participated which randomly allocated into two groups. The first group consisted of students who learned teeth color matching methods practically. In the second group, training booklet was used for learning. Using Vita Classic shade guide series, 4 color samples were chosen and the students of each group were asked to determine samples’ color, before, after and one month after the training. Booklet learning group was more successful in determining fourth color sample. However, in no studied group and no used samples, the results of one month after learning were not better than that of before learning. Also generally, no significant relationship was found between the color matching accuracy, using glasses, and sex of participants. The use of booklet learning was more effective than practical learning in color matching accuracy for dental students. Also, using glasses and sex were not effective on their color matching accuracy

According to many uses of MTA in different treatments, studying about its properties like the setting time, is of great importance. The aim of this study was to compare the initial and final setting time of an Iranian MTA and a foreign MTA.
Seven samples were in each group; for measurement of initial and final setting time of MTAs, a mold with dimension of 2×10 mm was prepared. The cements after mixation were put into an incubator with temperature of 37ₒC and humidity of 90%. After mixing of cements, a Gilmore needle with a weight of 100 gr and active tip of 2 mm was used vertically on the surface of MTA for measurement of the initial setting time. Setting was measured by the start of cement mixation to the time the tip of the needle didn’t penetrate to the surface of MTA. For measurement of the final setting time a Gilmore needle with a weight of 456 gr and active tip of 1mm was used vertically on the surface of MTA. The ANOVA test followed by Tukey test was used for comparison of the mean setting time between an Iranian and foreign MTA. The statistical difference was considered significant at the level of 0.05.
Resultes: The mean initial setting time Angelus and Root MTAs were 13.57±0.91 and 11.14±0.92 min, the mean final setting of Angelus and Root MTA, were 48.93±1.54 and 37.86±1.5 min while the initial setting time of Angelus MTA lasted for 0.53±43.2 more min than Root MTA (P=0.001). The final setting time of Angelus MTA took longer for 110.7±0.82 min than Root MTA (P=0.001).
The initial and final setting time of the Iranian MTA was shorter than the foreign one and thus it could a more alternative option in this respect.

The aim of this study was to evaluate the effects of two fluoride containing mouth rinses on the color stability of two different resin composites.
27 specimens (2×4×5 mm) were prepared from each of the following materials: a micro filled composite (Gradia, GC) and nanohybrid (Grandio). The specimens were polished by Soflex fine and superfine disks and then incubated in artificial saliva at 37°C for 24 h. The baseline color values (L, a, b) of each specimen were measured using an Easyshade spectrophotometer according to the CIELab color scale. The specimens were immersed in 20 mL of each mouth rinse and stored in an incubator at 37°C for 12 h. After incubation, the color values of all specimens were measured again, and the color change value (ΔE) was calculated. Data were analyzed by a 2-way analysis of variance at a significance level of 0.05.
None of the mouth rinses created clinical significant color changes in the samples. There was no statistically significant difference among color susceptibility between resin composites (P=0.330). The interaction between the effect of mouth rinses and type of restorative materials was not statistically significant (P>0.05).
Accordance to the results of this study, the fluoride containing mouth rinses does not create color change in resin composites.

Despite the reduction of incidence of dental caries in recent years, this disease is common and many efforts were conducted to decrease the prevalence of dental caries. On the other hand secondary caries lesions are the main reason for replacement of direct restorations. Therefore, the aim of the current study was to evaluate suitable methods of preparation and restorative materials to reduce caries recurrence.
In this experimental study, eighty human teeth were collected and stored in normal saline. The teeth were soft-tissue debrided and cleaned with water/pumice slurry and rubber cups in a low-speed handpiece. Speciments were randomly divided in two main groups. Cavities were prepared with diamond burs or Er:YAG laser (10 Hz, 300 mJ, 3W). Each group was divided into 4 sub-groups, and restored with a glass-ionomer cement (Fuji IX), resin modified glass-ionomer (Fuji II LC), total etch bonding composite resin or self-etch bonding composite resin. The specimens were submitted to pH cycling. Speciments were then sectioned, polished and Vickers microhardness measurements were performed on each specimen. Differences among the medians were analyzed using two way ANOVA test at a 95% confidence level and Tukey test.
Statistical analysis showed significant difference in the type of substrate (enamel, dentin) in both main groups (P The Er:YAG laser used for cavity preparation and different types of restorative materials used did not show the ability to guarantee significantly more acid-resistance tooth structure against demineralization.

Debonding is the most commonly encountered failure in teeth restored with fiber posts that mainly occurs at the weakest interface (dentin-cement interface). Thus, reinforcement of this interface is mandatory. The aim of this study was to evaluate the effect of different root dentin surface treatments after post space preparation on bond strength of fiber posts cemented with a self-adhesive resin cement.
Forty extracted sound single-rooted teeth underwent root canal therapy. After post space preparation, the teeth were assigned to four group of 10 teeth according to the type of dentin surface treatment: Group 1: 2% chlorhexidine rinse, group 2: 37% phosphoric acid etching and then irrigating with saline, group 3: rinse with xylene and then irrigation with saline, group 4: rinse with saline (control group). Then, fiber posts were cemented with Total cem cement and the teeth were sectioned horizontally. Specimens were observed under a stereomicroscope at X10 magnification and failure modes of each group were determined. Results were analyzed by one-way ANOVA.
There was no significant difference between the mean bond strength of the four groups (P=0.174). The highest mean bond strength value was found in phosphoric acid group (8.18±3.19 MPa) and the lowest belonged to the control group (6.21±1.81 MPa).
Our results showed that dentin surface treatment with phosphoric acid before cementation of fiber posts with a self-adhesive cement improves the bond strength.

Hepatitis B is an important infection in dentistry necessitating the use of disinfectants to prevent its transmission. This study compared the efficacy of 2/100 sodium hypochlorite disinfectants manufactured by four different manufacturers namely Ashimashi, Paknaz, Vitex and Active against hepatitis B virus (HBV). In this experimental laboratory trial, serum of 10 hepatitis B patients was poured into microtubes and Ashimashi, Paknaz, Vitex and Active disinfectants were added to them. Polymerase chain reaction (PCR) was performed with viral diagnostic kits to diagnose the virus genome. Real time PCR was performed before and after incubation with the disinfectants. The reductions occurred in the viral load of HBV were statistically analyzed by Kruskal-Wallis and Mann-Whitney U tests. No significant antiviral efficacy was noted following the application of Ashimashi 2/100 sodium hypochlorite disinfectant. Paknaz showed the highest efficacy against HBV. Vitex and Active ranked next with significant differences (P<0.0001). Under the study limitations, Paknaz 2/100 sodium hypochlorite solution was the most effective while Ashimashi 2/100 sodium hypochlorite disinfectant did not show adequate efficacy against HBV.

Hepatitis B is an important infection route in dentistry requiring different disinfectants to prevent its transmission. The aim of this study was to compare the effects of chemical disinfectants (FD366, ISORAPID and 5% sodium hypochlorite 2/100) to remove Hepatitis B infections from the dental surfaces. In this experimental laboratory trial, serum of 10 HBV patients was poured into microtubes, FD366, ISORAPID and hypochlorite disinfectants were added to them. PCR experiments with viral diagnostic kits were used to diagnose the virus genome. Real time PCR was used to evaluate after incubation with the disinfectants. The reductions occurred in the viral load of Hepatitis B were statistically analyzed using Kruskal-wallis and Mann-Whitney U tests. No significant antiviral efficacy was noted following the application of FD366 and ISORAPID disinfectants (P=0/07). However, hypochlorite showed the most efficacy to disinfect Hepatitis B and a significant difference was found among them (P<0.0001). Under the study limitations, FD366 and ISORAPID disinfectants did not show adequate efficacy to remove Hepatitis B virus. Hypochlorite was the most effective disinfectant.

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 & 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 (5-50oC). The teeth were then immersed in 0.5% basic fuchsin dye for 24 hours at 370C, 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.

To evaluate the effect of polishing on surface roughness of silorane-based composite using profilometery and Scanning Election Microscopy (SEM) and compare it with that of a methylmethacrylate-based composite and a glass ionomer. In this study, 3 groups (n=28) were tested: specimens of two composites (Filtek P90 and Filtek P60) and a glass ionomer (Fuji IX) which were prepared in polyethylene molds (4 mm diameter×10 mm height). Half of the specimens in each group were finished with 180-grit silicon carbide paper and the remaining were finished with 180-grit, and subsequently polished with 250, 400, 800, 1000, 2000, and 2500-grit silicon carbide papers. The surface roughness was evaluated using a contact profilometer and then mean (Ra) and maximum (Rmax) of surface roughness were recorded. Then, the surface of 4 specimens of each subgroup was observed under SEM. Statistical analysis was performed with T-test, ANOVA and Dunnett T3 tests. In all materials, Ra was different between polishing with 180 and 2500-grit silicon carbide papers. In 180-grit group, only Ra of Filtek P60 and Fuji IX showed significant difference (P=0.01). In 2500-grit group, there was no significant difference between the Ra of Filtek P60 and Filtek P90 (P=0.56). Polishing is recommended for the glass ionomer and posterior composite restorations.

Polymerization shrinkage in Methacrylate-based composite is one of the most important factors in composite restorations failure. Silorane-based composite is introduced to compensate this drawback and claimed to have low shrinkage. The aim of this study was to evaluate the polymerization shrinkage of these two composites. In this experimental study, 5 disk shape samples for each resin composites were placed in the centre of metallic ring bonded to microscopic glass slab. Top surface of ring was covered by a glass cover slip. Glass slab and sample were placed on a special LVDT holder in order to light cure from bottom surface and to measure the polymerization shrinkage. In this study, Deflecting Disk method and LVDT (linear variable differential transducer) was used for dimensional change measurement of resin composites. In this study, two LED curing units were used for composite polymerization. The mean of polymerization shrinkage in Z250 cured with LED and High Power LED was 11.15±0.08µm and 11.51±0.17µm, respectively (P=0.094), and in P90 cured with LED and High Power LED was 1.08±0.06µm and 1.16±0.12µm, respectively (P=0.019). Silorane-based composite (P90) showed significantly less polymerization shrinkage than that of methacrylate-based composite (Z250). For the two types of composite, there was no significant difference between the two curing units in polymerization shrinkage.

There is concern that leached components from dental composites may cause adverse changes in the reproductive health. This study aimed to assess the effects of leached components from a hybrid resin composite on the reproductive system of male mice. In the present animal study, twenty adult Syrian male mice were divided into two groups of 10 mice each. In the test group, components which leached from samples made from Filtek Z250 resin composite into 75% ethanol were daily administered to the mice for 28 days. In the control group, the procedure was repeated in the same way as the test group but without placing composite samples in the solution. Then, the body weight, weights of paired testes, Gonado Somatic Index, sperm viability, sperm motility, epididymal sperm reserve and daily sperm production were recorded. Four male mice in each group were mated with untreated female mice for 10 days. After that, the number of pregnant females and number of infants were recorded. The data were analyzed using repeated measures ANOVA, Chi-square test and t-test. There was a significant reduction in the sperm viability and sperm motility of male mice in the test group compared to the control group (P=0.001). There was no any significant differences in other parameters between two groups (P>0.05). This study showed that the leached components from resin composites cannot cause infertility but they could potentially cause some adverse effects on the reproductive system of male mice.

Temperature rise occurs during photoactivation of dental composites due to the exothermic polymerization reaction and different curing units. The aim of this study was evaluation of temperature rise in two kinds of composites with different curing units. In this experimental study, five samples of each composite resin (Filtek Z250, Filtek P90) were placed in two-millimeter deep Teflon molds which were 4mm in diameter. Curing was done from top surface with LED, high power LED and argon laser and temperature was recorded by a thermometer placed under the samples. After reaching room temperature, samples were cured and the temperature was recorded again. The time of maximum temperature was also recorded. The data were analyzed by two-way ANOVA and Tukey HSD. Composites and curing units had statistically significant influence on the temperature rise (p<0.001) Silorane-based composites showed significantly higher temperature rise than methacrylate-based ones. A significantly lower rise in temperature occurred when illuminationwas performed by argon laser. There was no significant difference in temperature rise between the two types of LEDs. The type of composite had no effect on the time of maximum temperature and in all samples the maximum temperature was recorded at the beginning of irradiation. Silorane-based composites showed higher temperature rise than methacrylate-based ones. Argon laser revealed less heat than LEDs. The maximum temperature rise was recorded at the beginning of irradiation.

Detection of caries in early stages is necessary for prevention and conservative treatment. The aim of this study was to evaluate the accuracy of laser fluorescence (LF) using DIAGNOdent pen and to compare it with conventional Bite-Wing (BW) and Digital Radiography (DR). In this survey, eighty extracted molars and premolars were mounted in stone blocks to simulate contact points. Proximal surfaces of each tooth were examined with LF. The teeth were also diagnosed using BW and digital radiography. After these procedures, the teeth were histologically prepared and assessed for caries extension as the gold standard. Sensitivity, specificity, positive and negative predictive values and accuracy were calculated for each diagnostic system in comparison with the gold standard. Cut-off points were calculated with ROC analysis. Comparisons between the accuracy of methods were performed using McNemar test. At dentinal caries, LF had the highest sensitivity and specificity (0.82 and 0.84, respectively). For detection of early inter proximal caries, the sensitivity of LF (0.74) and specificity of DR (0.95) were the highest. The LF positive predictive values were the least and negative predictive values were the most. There was no significant difference between conventional and digital radiography in the detection of interproximal caries. DIAGNOdent might be a useful additional tool in detecting early interproximal caries, but due to the false positive responses at decision making for restorative treatments, auxiliary methods should be used.

The reported bond strengths of resin cements to metal alloys depend on the metal used, the conditioning methods and the adhesive resins. The aim of this study was to evaluate the bond strength of resin cements to two alloys (Degubond 4 and Verabond) after sandblasting or using Silano-Pen. Eighty disk shaped specimens (6mm diameter and 2mm thickness) of Verabond or Degubond 4 were cast according to the manufacturer's instructions. After mounting in auto polymerizing acryl, all samples were polished with a 600 grit silicon carbide paper under water. Half of each alloy’s samples were randomly sandblasted with 50 µ Al2O3 and the other half were flamed with Silano-Pen device after sandblasting with 110 µ Al2O3. Cylinders of composite resin (Z250) were cured and then cemented to the prepared substrates by either Panavia F2 or RelyX Unicem. All specimens were stored in distilled water at 37oC for 24 hours and were subjected to 2000 thermal cycles (5-55oC), then submitted to shear bond strength (SBS) test using Universal Testing Machine at 0.5mm/min speed, until failure. SBS was analyzed by three way ANOVA (α=0.05). Failure patterns were determined using stereomicroscope with 40X magnification. Both cements provided stronger bond to Verabond compared to Degubond 4 (p<0.001). Comparing the surface treatments, Silano-Pen provided higher SBS of RelyX Unicem to both alloys. Panavia cement resulted in higher bond strengths to sandblasted Verabond alloy (p=0.003), but after treatment with Silano-Pen device RelyX Unicem showed higher bond (p=0.011). When cementing Verabond or Degubond 4 by RelyX Unicem, Silano-Pen provided a stronger bond, but in case of using Panavia F2, treatment with Silano-Pen or sandblast resulted no difference in bond strength.

The establishment of reliable bonds at root-post-core interfaces is critical for the clinical success of post retained restorations. Severe stress concentration at post-cement interface increases the probability of post debonding from the root. The aim of this study was to investigate the effects of different surface treatments on bond strengths of a non-metallic post in the root. Fifty extracted human canines or premolars that had just one root canal were endodontically treated. D.T Light Posts (RTD/France) recieved surface treatments in five categories: 1) Application of silane 2) Sandblast with Alumina particles 3) Sandblast with Alumina particles + application of silane 4) Etching with hydrofluoric acid + application of silane The posts were cemented in roots using panavia F 2.0 resin cement. A push-out test was performed on three different sections of each root to measure bond strengths. Data were analyzed with ANOVA and Post hoc tests at P<0.05. Failure modes were observed under a stereomicroscope (10 ×). Surface treatments used in this study (silane application, sandblast, sandblast + silane, HF etching + silane) did not increase the push-out bond strengths of fiber post used in this study. (P>0.05) The most failures in different groups of surface treatments occurred at the cement material-post interface. The use of silane, sandblast method and etching with HF did not increase the push-out bond strength of fiber post used in this study.

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.

Polymerization of resin-based dental materials is not complete; and the release of unreacted monomers has undesirable effects on biocompatibility and integrity of material. The aim of this study was to evaluate the type and effect of dentin bonding agents, type of light curing unit, the distance between the tip of curing unit and surface of bonding agents on monomer leaching. This experimental study used 40 sound extracted teeth, with prepared cavities about 3x3x2 and 3x3x4 mm on the smooth surfaces. A self-etch bonding (Clearfil SE Bond Curary, Japan) and one etch and rinse (Scotch Bond multipurpose, USA) were applied on cavities according to the manufacturer’s instruction. The bonding agents were cured with halogen (Optilux 501, Colten) and LED (Ultalume 2, Vivadent) lights. The samples were saved in pure methanol with 37 ° C for 24h. Liquids were studied with gas chromatography (GC) for detection of different monomers. Data were analyzed using 3-Way ANOVA and Independent T-tests. The type of bonding agent had significant effect on monomer release. Scotch Bond released more monomer than Clearfil SE Bond (P=0.001). The effect of light curing unit on monomer leaching was not significant, but the samples of Scotch Bond with more distance released more monomer. Only HEMA monomer was detected from dentin bonding agents in this study. Scotch Bond released more HEMA than Clearfil SE Bond. Halogen and LED lights had no significant effect on monomer leaching. More distance between the tips of light causes less degree of polymerization.

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/cm2) 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 40×magnification. 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.

The main objective of this study was to determine the effect of polyethylene fibers and veneering composites in fiber-reinforced resin systems on the opacity (contrast ratio). The specimens were divided into four groups. Two groups were used as the control groups, with no reinforcement. The fibers of polyethylene (Fibre-Braid) with special basement composites were used as the reinforced framework materials. Filtek Z250 and GRADIA (shade A2) were used as veneering materials. The total thickness of samples was 3 mm with 13 mm diameter. Specimens were prepared in disk shaped metal mold. The composite materials were light-cured according to their manufacturer's instructions. The contrast ratio (CR) of each specimen was determined on black and white backgrounds using reflection spectrophotometer. Reflectance was measured at intervals of 10 nm between 400 nm and 750 nm. Data were analyzed by two-way ANOVA and Tukey HSD test. When contrast ratio were compared among the different types of materials statistically significant differences were observed in both veneering composites (P<0.05). The Z250 resin composite had the lowest CR. It was shown that CR tended to decrease as the wavelength of incident light increased from 400 nm to 750 nm. On the other hand, the most differences in CR between groups were found in longer wavelengths. It was found that polyethylene fibers reduced the amount of the translucency in FRC samples. The results of this study indicate that light reflectance characteristics, including the wavelength dependence, play an important role for the CR of a fiber-reinforced composite.

In spite of the advances achieved in the field of dentin adhesives, the longevity of bond to dentin is still a challenge. According to recent studies, Matrix Metaloproteinase (MMP) inhibitors can increase clinical longevity of bonding and decrease leakage. The aim of this study was to evaluate the amount and pattern of doxycycline release from an experimental dentin adhesive containing this MMP inhibitor. In this experimental study, specimens containing 0.25 and 0.5 loading percent of doxycycline in an experimental monomer were prepared in cylindrical moulds of 12 mm diameter and 2 mm thickness. The adhesive monomer was composed of 12 wt% Bis-GMA, 10 wt% TMPTMA, 28 wt% HEMA and 50 wt% ethanol. Camphorquinone and amine were used as initiators. Addition of 0.25 and 0.5 w% doxycycline showed linear release in both groups. Increasing the loading percent of doxycycline caused more release. The release continued during the test period. Doxycycline release was observed from the experimental adhesive. Further studies in this field will help in preparing adhesive systems with more clinical longevity.

Decreasing the hardness of dental restorative composites after curing in oral environment can influence their clinical durability. The aim of this study was to evaluate the effect of food-simulating liquids such as 25%, 50%, 75 % ethanol and 50 % heptane on surface hardness of two composites - (Gradia and P60) after curing and immersing time of 24 hours and 7 days. 45 specimens of each composite were prepared in a stainless steel mold with 6 mm diameter and 2 mm depth. 5 specimens of each composite were tested for microhardness immediately after curing as the control group. The other specimens of each composite were randomly divided into eight groups. Each specimen was immersed in one of the following solutions 25%, 50%, 75 % ethanol and 50 % heptane for either 24 hours or 7 days. Then the specimens were taken out of the solutions and washed and dried and transferred to the refrigerator until performing the test. In standard conditions, surface microhardness of specimens was evaluated by the microhardness device based on Vickers. The data were analyzed by one way ANOVA 3 way ANOVA and Tukey Post Hoc tests. The level of significance was set at p<0.05. Surface hardness of P60 composite was higher than that of Gradia. An analysis of variance in gradia and p60 showed significant difference between the control and all the other groups (P<0.05) except the 25% ethanol (P=0.514). After 24 hours all the solutions had significant effect on Gradia (P<0.05) except 50% and 75% ethanol (P=0.793). After 7 days all the solutions had significant effect on Gradia except 50% and 25% ethanol (P=0.385)and 50% and 75% ethanol (P=0.150) According to P60 after both 24 hours and 7 days all the solutions had significant effect on the hardness. 50 % heptane increased the hardness (P=0.00). 75% ethanol significantly decreased the hardness (P=0.000) followed by 50% (P=0.001) and 25% ethanol (P=0.007). Based on the results of this study, the effect of time was not significant. P60 showed to be more resistant. 75% ethanol had much more effect followed by 50% and 25% ethanol. Heptane increased the mean surface hardness.

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.