فهرست مطالب پروین میرزاکوچکی بروجنی

Amalgam is a safe and effective restorative material in direct restorations. One of the conservative methods for the repair of a fractured amalgam restoration is the use of adhesive materials like composite resin. Therefore the aim of this study was to evaluate the bond strength of composite resin to amalgam with the use of different bonding agents.
In this in vitro study, 52 acrylic cylinders were made and amalgam containing 43% Ag was condensed into these cylinders. After keeping the amalgam samples at room temperature for 24 hours, the amalgam surfaces were abraded with a diamond bur and all the samples were immersed in an ultrasonic bath. Then the specimens were divided into 4 groups of 13 samples, and each group was treated with different boding agents as follows: group (1), amalgam alloy primer total etch (Single Bond); group (2), amalgam alloy primer self-etch (G Bond); group (3), amalgam G Bond; and group (4), amalgam Single Bond. Composite resin was bonded to prepared amalgam specimens with the use of translucent polyethylene mold and cured by LED Turbo, followed by testing with an Instron machine for shear bond strength. Finally data were analyzed with one-way ANOVA and LSD tests.
In this study, the highest bond strength value was recorded in specimens bonded with G Bond bonding agent (9.06 MPa) and the lowest value was recorded in specimens bonded with Single Bond bonding agent (5.14 MPa). The mean shear bond strength values in 4 groups exhibited statistically significant differences (p value = 0.001).
G Bond bonding agent yielded higher bond strength between amalgam and composite resin than other bonding agents used in this research.

The most important features of dental materials is physical surface. One of these features is interfacial effect of solid–fluid that evaluated in standard situation with contact angle and the surface tension is directly related to it. This study was aimed to evaluate two mouth-rinse contact angle with difference base on two restorative materials.
Method & Material: In this experimental study we has made 15 composites dick, 15 Glass Ionomers) disk with 6mm diameter and 2mm thickness and good surface roughness and used artificial saliva as control group, chlorhexidine and persica mouth-rinse and Contact angle of each instilled drop of liquids on the surface of restorative materials was measured whit profile imaging in the same condition. The obtained data were analyzed by ANOVA and Tukey.
the most contact angle was in artificial saliva on composite surface (55.7 ͦ) and the least of them was chlorhexidine in Glass Ionomer surface (33 ͦ). Also there was Significant differences between all conditions studied (P in this study Between two restorative materials, composite (hydrophobic) and glass ionomer (hydrophilic) contact angle of artificial saliva, persica and chlorhexidine on the more hydrophilic material (glass ionomer) is lower and among the solutions used, chlorhexidine contact angle on the both restorative material is less.

Sensitivity is one of the most common complications of vital tooth bleaching and different materials such as fluoride can be used to reduce such tooth sensitivity. The aim of this study was to evaluate the effect of fluoride on tooth color changes before and after using bleaching materials.
In this clinical trial, 24 students aged 18‒25 years were selected. Initially, the color of 6 sound anterior maxillary and mandibular teeth was recorded under the same environmental condition and then photographic records were provided. The subjects were randomly divided into 3 groups. The subjects in group 1 used carbamide peroxide (CP) for at least 6 hours every night during sleep; the subjects in group 2 used phosphate fluoride (PF) before using CP and subjects in group 3 used phosphate fluoride (PF) gel after having used CP. After the tooth bleaching period, the tooth colors were recorded using Vita shade guide and the digital RGB (red, green, blue) method to evaluate the effect of the time of fluoride use on tooth color changes. Data were analyzed with paired t-test and ANOVA (α = 0.05).
Statistically there was no significant difference between groups in term of color changes using vita (p value = 0.154) and the RGB method (p value = 0.147).
The results of this study showed that use of PF gel before and after tooth bleaching did not affect the color change process.

Composite Resins with different chemical structure are affected by lots of stimulus within mouth's environment that make them degenerated by the time, change their characteristics. The purpose of this research is to evaluate the effect of five different Food-Stimulating liquids on water sorption and the solubility of Methacrylate and Silorane based Composite resins.
Methods and materials: In this in vitro study, twenty five discs with 1mm thickness and 6mm diameter were prepared by filling aluminum molds with two kinds of composites, Filtek Z350 and P90. Samples were light- activated from top surface, then stored in coded dishes with silica gel, and transferred to the oven with 37c̊ to desiccate them for 24h. Samples were weighed by digital balance (M1) after 24h, and then stored in five Food-Stimulating liquids (Acid citric %2 N, distilled water, Ethanol %75, Heptan, and artificial saliva). After one week, samples were weighed again and the result (M2) was recorded. Samples were placed in silica gel containers until the mass variation became less than ±0.1mg (M3). After last desiccation to get the V (body mass) of samples, the diameter and the thickness of discs were calculated. Results were analyzed with Tukey test.
Results In this research, the solubility of composite Z350 in heptan was the highest (0.040 µg/ mm³) and in distilled water had the lowest solubility (0.009 µg/ mm³).Differences between distilled water, alcohol and heptan were statistically significant (p0.05). The amount of solubility of P90 in different solutions had no statistically significant difference (p>0.05). But, water sorption in artificial saliva was higher than other solutions (P The results showed that solubility of P90 was lower than Z350 but there is no statistical difference between water sorption of two materials.

Today, the high silver amalgam has been mentioned because of its appropriate properties so purpose of this study was the evaluation of bond strength of composite to high silver amalgam by using different bonding agents.
Methods and materials: In this experimental study, 52 acrylic cylinders were made and amalgam which contains of 60%Ag were condensed into this cylinders, amalgam surfaces were roughened by diamond bur and all samples were immerged in ultrasonic bath. Then specimens divided into 4 groups of 13 samples: group (1) Amalgam Alloy primer single bond, group (2) Amalgam Alloy primer G.bond, group (3) Amalgam single bond .bond, group (4) Amalgam G.bond. Resin composite was bonded to prepared amalgam specimens by using translucent polyethylene mold and cured by LED Turbo and tested by universal testing machine for shear bond strength and finally data were analyzed with one-way analysis of variance and LSD test.
In this study, the greatest values of bond strength were related to bonded specimens of use of Alloy primer G.bond bonding agent and lowest values were related to bonded specimens use of single bond bonding agent and mean shear bond strength in 4 groups had statistically significant difference (P=0.002).
Combination of alloy primer and G.bond. bonding agent increased the bond strength between composite and high silver amalgam significantly

Intracanal medicaments can affect the bond strength of composite to dentine. The aim of this study was to evaluate the effect of 2% chlorhexidine (CHX) gel as an intracanal medicament on shear bond strength of three different composite resins to dentin. In this in-vitro study, 60 intact extracted human premolars were utilized. Each tooth was sectioned vertically and dentin of the buccal surface was exposed. Then, specimens were divided into six groups of 10 teeth. In groups 1-3, dentin was exposed to CHX and in groups 4-6, dentin was exposed to saline. All prepared surfaces were rinsed with distilled water and dentin bonding agent specific for each composite was applied on the dentin surfaces. Z100, Z350 and P90 composites were applied to the treated surfaces and cured. The shear bond strength was recorded in Newtons and converted to MPa. Data were analyzed using the Kruskal-Wallis and MannWhitney U tests. The lowest mean shear bond strength was reported for normal saline and Z100 composite group (18.47 MPa) and the highest for CHX and Z350 group (42.26 MPa). No statistically significant difference in bond strength values was found between normal saline and CHX groups (p>0.05). There was a significant difference in bond strength values of different composite resins in normal saline (p<0.05) and also in CHX groups (p<0.05). chlorhexidine gel 2% slightly but not significantly increases the mean shear bond strength of composite to dentin. The type of composite influences the shear bond strength to dentin.

Fissure sealants are applied in order to obliterate the fissures and isolated them from surrounding decay-causing environment. If these materials are lost، they should be repaired to provide protection from tooth caries. The aim of this study was to evaluate microleakage of repaired fissure sealants after using preparation methods such as prophylaxis، enameloplasty، air abrasion، application of bonding agents and beveling of fissures. In this in vitro experimental study، fifty caries-free third molars were used. After cleaning by prophylaxis and acid etching، the fissure sealant (Fissurit FX) was placed on the teeth while a periodontal probe was placed on one half of the occlusal surface to create a break point sealant before curing، which was removed after light-curing. The sealant of one half of the surface was removed and the teeth were randomly placed in one of the five groups: 1) prophylaxis and etching (control); 2) enameloplasty with a round carbide bur and etching; 3) air abrasion and etching; 4) etching and application of the bonding agent; 5) beveling the margins of the buccal aspect of the occlusal fissure and etching. After thermocycling and sealing the teeth، they were immersed in 1% methylene blue for 48 hours. Then the teeth were sectioned longitudinally in a mesiodistal direction. The sections was examined under a stereomicroscope for microleakage. Data were analyzed with Kruskal-Wallis test. The highest and lowest rates of microleakage were seen in group 2 (enameloplasty) and group 5 (bevel of the buccal fissure)، respectively. Statistical analysis with Kruskal-Wallis test showed no significant differences between the groups (p value = 0. 19). This study did not demonstrate any one single method of repair to be superior to the control method for reapplication of the sealant. It seems that persistence of each of these methods depends on the results of future studies، especially clinical studies.

Composite resins require time to complete their polymerization. This process usually reaches its maximum rate after 24 hours. On the other hand، immediately after restoration، water sorption results in hygroscopic expansion of composite resins and the mentioned two factors usually reachequilibrium after a week. Considering the effect of mentioned processes on the microleakage of composite restorations، the purpose of the present study was to evaluate the effect of finishing and polishing time on the mean microleakage of composite restorations. In this in-vitro experimental study، 60 sound human premolar teeth were selected. A standard Class V cavity was prepared measuring 1. 5 mm in depth، 3 mm in width and 2 mm in length on the buccal surface of each tooth and incrementally restored with composite resin. Next، the teeth were randomly divided into 4 groups. The teeth in groups 1، 2، 3 and 4 were finished and polished immediately، 15 min، 24 h and one week after storage in distilled water at 37°C، respectively. Specimens in each group were subjected to 500 thermal cycles. The teeth were then coated with adhesive wax and nail varnish and immersed in 2% fuchsin solution for 24h. The specimens were washed and each sample was longitudinally sectioned in half by a diamond saw. Both halves were evaluated in terms of dye penetration under a stereomicroscope at 28X magnification. For each sample، the section with greater degree of microleakage was selected. Kruskal Wallis test and Mann Whitney U test were used for data analysis with a 99. 1% confidence interval. The lowest mean microleakage was observed in the occlusal margin of group 3 teeth; while the highest mean microleakage belonged to the occlusal and gingival margins of teeth in group 2. A significant difference was noted between the 4 groups in occlusal margin microleakage (P<0. 009). However، no such difference was found in gingival margin. This study showed that the finishing and polishing timewas effective on the mean microleakage in the enamel margin of composite restorations. The best time of finishing and polishing was 24h after the restoration. Time of finishing and polishing had no effect on microleakage in dentin margins of restorations.

Posterior composite restorations are the one of the most usual dental treatments among patients. The goal of this study was determining dentists’ problems during and after treatment of posterior – composite restorations in the city of Isfahan. In this descriptive-analytical study، we used a questionnaire including questions about the problems of posterior composite treatments during and after operation among dentists in Isfahan in 2009-2010. The data were analysed by chi-Square test. The most frequent problem during composite restoration was achieving good proximal contact (30. 8%) and after it، sensitivity of teeth while chewing which would not be repaired by correct occlusion (34. 8%). Most of the dentists pushed the matrix strip toward the adjacent teeth while polymerization، applied the composite in different layer، did the company instructions for bonding layer and used wet polishing during restoration. Most of the dentists (55. 8%) used two step total etch dentinal bonding and selected the composite because of its ability in making isolation and good restoration (42. 5%). Providing correct education for the dentists and increasing their knowledge about these restorations result in reduction of associated problems during and after the operation.

Along with improvements in aesthetics and longevity of restorations, finishing and polishing, can produce potentially injurious temperature rise within the pulp chamber. The purpose of the current study was to find whether different polishing methods and thickness of composites have any effect on temperature rise of composite restorative materials. Sixty composite resin specimens 9 mm in diameter were prepared and assigned to three experimental groups with three sample thicknesses (2, 3 and 4mm). Each group was divided into four subgroups randomly. Polishing in subgroups 1 and 2 (continuous and intermittent dry polishing) and subgroups 3 and 4 (continuous and intermittent wet polishing) was carried out with a slow speed contra-angle hand piece at a medium speed for 120 seconds in a roll on motion. Immediately after polishing, temperature was measured on the top and bottom surface of each sample using a laser thermometer. One and two way ANOVA, Duncan, and paired T-test was used to analyze the data. The mean temperature rise after polishing in different methods was significant; continuous dry polishing produced the maximum temperature rise. In addition, increasing the thickness of composite resin up to 4mm did not significantly affect thermal transfer from the top surface to the base during polishing. Copious use of water coolant during finishing and polishing procedures is considered a simple and effective method for pulpal protection. Increasing the thickness of composite resin does not have a significant role in compensating the heat generated during polishing procedure.

Self-etching fissure sealants have been introduced recently, leading to elimination of etching and rinsing, reducing working time and consequently increasing child cooperation. This clinical study was conducted to compare the retention rate, caries occurrence and marginal integrity of a self-etching fissure sealant (Prevent Seal) with a conventional sealant (Concise) over a12-month period. In this clinical trial 192 first permanent molars of 48 children aged 7-9 years were selected. Self-etching sealants were randomly used for first permanent molars on one side of the mandible and contralateral side of the maxilla and conventional sealants (etch-and-rinse) were placed on the remaining first permanent molars. Clinical evaluation was performed at 3-, 6-, and 12-month intervals by a single blind examiner. The retention was classified as complete retention, partial loss and total loss. Caries incidence was assessed. Marginal integrity of sealants was also evaluated with modified U.S. Public Health Service (USPHS) codes. Data were analyzed with Friedman’s, Wilcoxon’s signed rank and McNemar’s tests using SPSS statistical software (α=0.05). At the end of 12 months Concise had higher retention rates (87.5%) than Prevent Seal (12.5%), with statistically significant differences (p value < 0.001). Regarding marginal integrity of the sealants, Concise yielded significantly better results than Prevent Seal at all the follow-up examinations (p value < 0.001). However, there were no significant differences in caries incidence between the two groups (p value = 0.99). The results indicated that retention rate and marginal integrity of self-etching sealants are less than those of conventional ones at 12-month evaluation period.

After orthodontic treatment, certain cases have high potential of relaps.These cases reqire fixed retainers.Fixed lingual retainers were introducsd in 1970s and In the last 20years several different techniques for bonding fixed retainers have evolved.Review report: This review carried out by use of searching in various databases including Pubmed and Google Web of Science from 1973 to 2011 on combination of the terms orthodontic retainer and resin bonded retainer. The indirect method requires a laboratory procedure for holding the retainer´s wire on teeth surfaces for bonding but in the direct method,the retainer´s wire needs to be prefabricated for fit the lingual surface of the teeth.Several methods have been used to hold the wire on the teeth surfaces. In this article,we introduce some methods. Perception of advantages and disadvantages of several methods of placing lingual retainer, which are simple and cost-effective,enable the dentist to choose the most suitable method.

Shear bond strength is one of the most important mechanical characteristics involved in clinical durability of tooth-colored restorations, which is directly related to polymerization shrinkage. This study evaluated the efficacy of two light-curing units (LED2 & QTH) and two types of dentin bonding agents (Excite & Clearfil SE bond) on composite resin shear bond strength to dentin. Forty caries-free sound human premolars were randomly divided into 4 groups of 10 after being disinfected with sodium hypochlorite. The occlusal surface of dentin in each specimen was exposed and flattened by a fissure bur; composite resin was bonded with Excite or Clearfil SE bonding agents and polymerized with QTH or LED2. Shear bond strength values of the specimens were tested in a Dartec universal testing machine. Data were analyzed by one-way ANOVA, two-way ANOVA and Dunkan test (α = 0.05). Maximum shear bond strength values were recorded in composite restorations bonded with Clearfil SE bonding agent and polymerized by LED2; minimum values were recorded in composites restorations bonded with Excite and polymerized by QTH. Statistical analysis showed statistically significant differences between the experimental groups (p value = 0.03). Under the limitations of this study, it can be concluded that two curing systems of LED2 & QTH are equally effective on shear bond strength of different bonding agents, whereas Clearfil SE bonding agent produces higher shear bond strength than Excite total-etch regardless of the type of light-curing unit.

Bleaching may cause decrease in Calcium, Phosphate and Fluoride content of enamel. However, the topical use of fluoride can help reabsorb those minerals. The aim of this study was to determine the effect of fluoride therapy before and after bleaching on enamel dye penetration. Sixty extracted carries-free human premolars were selected. All teeth surfaces were covered by nail varnish, except a square about 6 mm² on the buccal surfaces for exposure to fluoride and bleaching agent. The teeth were randomly divided into 5 groups (n=12) and then stored in artificial saliva at 37ºC for 7 days. Each group was processed as below: Group1: Specimens with no treatment were immersed in 50% silver nitrate solution. Group2: Specimens were bleached by 45% carbamide peroxide for 30 minutes twice a day for 5 days. Group3: the sodium fluoride varnish was used on specimens for 5 minutes. Group4: After bleaching like group2, specimens were stored in artificial saliva. Fluoride therapy was performed next like group3. Group5: All processes were conducted like group4 after fluoride therapy. All specimens were cut bucco-lingually along the longitudinal axis and stored in developer solution for 6 hours. Stereotactic microscope images were captured by digital camera for dye penetration assessment. Data was analyzed using SPSS (11.5) software and ANOVA and Kruskal Wallis tests. Data showed that bleaching can significantly (P=0.001) increase dye penetration. However, fluoride treatment can significantly decrease dye penetration (P=0.001). Fluoride therapy is highly recommended after bleaching process.

Microleakage is one of the most important complications of direct tooth-colored restorations. One of the described methods to reduce microleakage is the use of bonding agents after finishing restorations.The purpose of this study was to evaluate microleakage associated with class V composite restorations while using rebonding on restorative margins.Method and materials: A total of 48 extracted caries-free human premolars were selected. Class five cavities were prepared on the buccal surfaces of all samples. Occlusal margins were placed in enamel while gingival margins were placed in dentin.Teeth were randomly divided into four groups of 12. Group 1 was considered as the control group, which was restored without rebonding. In groups 2, 3 and 4, after finishing and polishing, rebonding was performed by Prompt L-Pop, permaseal and Clearfil SE Bond on the restoration margins respectively. Specimens were thermocycled for 500 cycles, sealed with two layers of fingernail polish except for the occlusal and gingival margins, and immersed in fuschine 2% for 24 hours. Specimens were longitudinally sectioned with diamond disk and studied under stereomicroscope. The data were analyzed with Kruskal-Wallis and wilcoxon tests. (α = 0.05). Kruskal-wallis test showed no statistically significant differences for microleakage on occlusal (P value = 0.075) and gingival margins (P value = 0.281) among the groups. Wilcoxon test showed significant differences between occlusal and gingival margins in Prompt L-Pop (P value = 0.023) and permaseal (P value = 0.026) groups, but between the other groups, this difference was not significant. (P < 0.05). The three bonding agents applied in this study do not seem useful in decreasing microleakage into enamel and dentin margins.

Bleaching teeth can lead to decreased calcium, phosphate and fluoride content of enamel which may cause decreased enamel micro-hardness. Reportedly, the topical use of fluoride can help regaining those minerals. The aim of this study was to evaluate the effect of fluoride therapy on enamel micro-hardness when used before or after bleaching.

Total of 60 premolar teeth were divided into 5 groups. The occlusal surface in all teeth were flattened and covered with nail varnish. Initially, all specimens were inserted in artificial saliva for 7 days. Group 1 used as negative control. Samples in group 2 were bleached 2 times with 30 minutes interval for 5 days, using %45 carbamid peroxide. Group 3 samples were exposed to fluoride varnish for 5 minutes. Group 4 exposed to fluoride varnish for 5 minutes, bleached 2 times for 30 minutes in 5 day intervals. Group 5 samples were treated same as group 4, however, followed by fluoride varnish for 5 minutes. Micro hardness for each group measured in 3 points after cleaning the occlusal section. The LSD and ANOVA tests were used for data analysis.

This study showed, reduction in enamel surface hardness can be compensated by fluoride application. Group 2 (bleached only) showed the minimum micro hardness (294.38), and group 3 (exposed to fluoride only) showed the maximum micro hardness (455.36).

Fluoride therapy can affect enamel micro-hardness before and after bleaching. The application of fluoride varnish is recommended after exposing teeth to bleaching agents.

Dentin hypersensitivity is a common condition of transient tooth pain associated with a variety of exogenous stimuli. The clinical cause of dentin hypersensitivity is exposed dentinal tubules as a result of gingival recession and subsequent loss of cementum on root surfaces. Two principal treatment strategies are used; Dentinal tubules can be covered by gingival grafts or dental restorations and desensitization of the nerve tissue can be done within the tubules using potassium nitrate. The Purpose of this study was to compare effect of two desensitizing agent nitrate potassium and sodium fluoride after peridontal surgery. In this clinical trial 12 patients that had peridontal surgery at minimum 3 quadrants, in each there was one sensitive tooth, were selected. The degree of sensitivity measured before using nitrate potassium and sodium fluoride the same as control group. Potassium and sodium fluoride gels used on the quadrants (upper or down. The degree of sensitivity measured after 7 and 14 days. Data analysis was done in SPSS software by Freedman and Willcoxon tests. After 7 and 14 days in the all groups, decrease of sensitivity was statistically significant. But after 14 days, between three groups, there were no statistically significant differences. Even though using of nitrate potassium 3% and sodium fluoride 2% cause significant reduction of tooth sensitivity in a 2 weeks period but in compare to the control group did not show any superiority. Further study is needed to confirm this result.

In patients requesting to bleach their teeth, bleaching treatment might affect microleakage of present restorations. Technique and concentrations of applied bleaching and bonding agents are some effective factors on microleakage of composite restorations. The aim of this study was to evaluate the effect of bleaching method on microleakage of resin composite restorations.Methods and Materials: 48 extracted carries free human premolars were selected and randomely divided into 4 groups. Class V cavities were prepared on buccal and lingual surfaces, with gingival margins located 1 mm below CEJ. In group one Cleatfil, SE- bond and Single bond applied on buccal and lingual surfaces respectively, and cavities restored by Z 250 resin composite. In group two, the cavities were restored as in group one and then were kept in distilled water for a period of one month. In group three, all the stages resembled group two and home bleaching regimen was used. In group four, all the stages resembled group two, but samples subjected to in office bleaching regimen. All the samples were thermocycled and examined for microleakage. Data analyzed using Wilcoxon, Kkruskal-wallis and Man-Whitney U tests (a = 0.05). Single bond compared to SE- bond provided the best post bleaching results regarding microleakage. The amount of microleakage was higher in office bleach technique in both margins. Single bond showed the best results regarding post bleaching microleakage. Bleaching had a negative effect on microleakage that was higher in office technique.