Showing 57 results for Strength
Abdolrahim Davari, Soghra Yassaei, Alireza Daneshkazemi, Mohadeseh Khosravanian,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: Orthodontic bracket failure during treatment is a common problem. With the introduction of low shrinkage composites the question is that whether: this sufficient has coefficient bond strength for bonding bracket during orthodontic treatment. The aim of this study was to compare the shear bond strength (SBS) of silorane-based and metacrylate-based composites to metal brackets.
Materials and Methods: 30 human premolar teeth were collected and divided into 2 groups. In group 1, 15 orthodontic brackets were bonded using silorane-based composite, in group 2, 15 orthodontic brackets were bonded using metacrylate-based composite. The shear bond strength of each specimen was determined in an Instron machine. Amount of residual adhesive remaining on each tooth was evaluated using a stereomicroscope. Data were analyzed using T-test to compare the shear bond strength between groups and LSD method to compare the Adhesive Remnant Index (ARI) scores.
Results: There was significant difference in the SBS between the test groups (P<0.001). The mean bond strength of bonding brackets to silorane-based composite was (42.42 ± 7.03) MPa, and the mean bond strength of bonding brackets metacrylate-based composite was (21.08±2.97 ) MPa. No significant difference in the ART was found between groups (P=0.66).
Conclusion: Silorane-based composite provided higher bond strength to orthodontic metal brackets.
Mehdi Araghbidikashani, Elham Esmaili, Gholamreza Eslami, Mohsen Nuori, Hasan Ghaffari, Abbas Salehi,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: The aim of this descriptive longitudinal study was to determine the type of teeth that were more prone in accidental bracket debonding and also to investigate the relationship between broken bracket bond and intervening factors such as age, type of malocclusion and sex.
Materials and Methods: We used a pilot study to determine the correct sample size for this study. According to the pilot study which consisted of 20 records of patients, it was concluded that 576 patient’ records was needed. The mean time for a bracket before it fails was also measured using Kaplan-Meier method. Cox regression analysis was done to examine the effect of age, gender, and class of malocclusion on each tooth with broken bracket. Data were analyzed using the software SPSS 20.
Results: Results showed that the percentage of unexpected broken bracket bond for each tooth varied and they were significantly related only in second premolars in both jaws with malocclusion that was different for each tooth (P=0.037, P=0.004).
Conclusion: Maxillary second premolars and mandibular second premolars had the highest rate of unexpected broken bracket bond in CL II CL I malocclusion respectively. Age, gender and malocclusion had no effect on the unexpected broken bracket bond for other teeth.
Alireza Daneshkazemi, Abdolrahim Davari, Farnaz Farahat, Neda Pazhoohi,
Volume 28, Issue 2 (7-2015)
Abstract
Background and Aims: The purpose of this study was to compare the effect of chlorhexidine 2%, ethanol 70% and sodium ascorbate 10% and delayed bonding for 1 week on the shear bond strength of composite resin to enamel after bleaching.
Materials and Methods: 90 human central incisors were divided into 6 equal groups: Group 1: no bleaching Group 2: bleaching with carbamide peroxide 45% for 45 minutes Group 3: bleaching + restoring specimens in distilled water for 1 week. In group 4, 5 and 6, after bleaching, 1 cc of chlorhexidine 2%, ethanol 70% and sodium ascorbate 10% were applied for 15 minutes. Composite cylinders were bonded on the buccal surfaces. Specimens were thermocycled for 1000 cycles and the shear bond strength test was done. Specimens were examined under stereomicroscope and SEM. Data were analyzed a sign ANOVA and Bonferroni test.
Results: The shear bond strength values were not significantly lower in the bleached teeth (group 3, 4, 5 and 6) than that of negative control group (group 1) (P=1.000, P=0.069, P=0.081, P=1.000) Bonferroni test results show significant difference between test groups (3, 4, 5 and 6) and group 2 (P<1.000, P=0.007, P=0.008, P<1.000) Under SEM, resin tags in group 2 was thinner and lesser than group 3, 4, 5 and 6. The most adhesive failures were in group 2.
Conclusion: Bleaching with carbamide peroxide and immediate bonding of composite decreased the shear bond strength. Sodium ascorbate 10% and delayed bonding for 1 week were the most effective way.
Mehran Bahrami, Maryam Memarian, Farinaz Khodadad Kashi,
Volume 28, Issue 3 (10-2015)
Abstract
Background and Aims: Residual ridge resorption is an unpredictable, unavoidable and time-dependent process which occurs in denture-wearing patients especially those who use mandibular dentures. This process causes more problems in mandible because of its less support, tongue forces and more resorption. Inserting implants in many of these patients requires bone grafts. Overdentures are also more expensive. Denture adhesives are the last option to improve retention and masticatory function in denture-wearers with severe resorption of alveolar ridge. Nowadays only a few denture adhesives are used in Iran and there is not much information about their standard features including, pH, bond strength and washability. The objective of this study was to examine and compare the mentioned characteristics of four denture adhesives (Professional, Corega, Fittydent and Fixodent) and to introduce the most suitable denture adhesive for clinical use.
Materials and Methods: All the methodologies of ISO 10873:2010 were applied. To measure the pH value, 1±0.1g of each denture adhesive was diluted with 5g of propylene glycol and mixed with water. Using pH meter, pH of each group was measured separately for 4 times (n=4) and results were recorded. For the washability test, 4 dentures were fabricated (n=4) and each group of denture adhesives was placed on a denture according to manufacture instructions. For simulating mouth environment specimens were placed in water at 37±2 ̊C bath for 1 hour and then washed with a plastic brush. Specimens were examined for any residual adhesive and the results were recorded. For bond strength test, a sample holder was gently filled with denture adhesives and was attached to the holding arm of bond strength testing device (Santam, STM 20, Iran). Specimens were placed in 300ml water bath at 37±2 ̊C for 10 minutes, and then shaken to be dried and placed in the bond strength testing device. 10N force with 5mm/min rate was applied to the specimen. The force was maintained for 30s and then device arm was pulled back and the highest number was recorded with computer software (Santam Machine Controller v4.19, Iran). The test performed 8 times (n=8) for each adhesive and 8 results were recorded. Data were analyzed using ANOVA test for comparing the bond strength with a significant level fixed
at 0.05.
Results: Professional and Corega adhesives had more neutral pH than that of Fittydent and Fixodent which were more acidic. Washability test showed no remaining mass of any adhesive and there was not any statistically significant difference between groups (P>0.05). Fittydent and Corega adhesives showed higher bond strength than that of Professional and Fixodent and this difference was statistically significant (P<0.05).
Conclusion: Professional and Corega adhesives had less acidity. Thus they cause less harmful effects on the oral mucosa than that of Fittydent and Fixodent and should be indicated in patients with little-tolerant oral mucousa such as diabetous, iron-deficiency anemia and hypertention. All the groups had acceptable washability. Fittydent and Corega had higher bond strength than that of Professional and Fixodent. Therefore in complete-denture-wearers who require more retention as a result of severe ridge resorption, macrotruma, and maladaptiivity, Fittydent and Corega seems to be more acceptable.
Nina Rahshenas, Mohammad Hasan Salari, Maryam Koukabi Salehi, Mahshad Mohebbi,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Debonding at the cement-dentine interface is the main reason of failure in restoration of endodentically treated teeth with fiber posts. The aim of this study was to compare the effect of Starfill 2B danville and Panavia F2 kuraray cements on the retention of fiber posts to root canal dentin.
Materials and Methods: Twenty extracted mandibular premolar teeth which had single root canal were endodentically treated and decoronated. Teeth were randomly divided into 2 groups, (n=40). Fiber posts were cemented using 2 dual cure resin cements. Group A was cemented with Starfill 2B Danville and group B was cemented with Panavia F2 Kuraray. Each root was mounted in acrylic resin and then sliced in 2 parts. The retention strength of each specimen was determined using push-out test using a universal testing machine. Data was analyzed using T-test.
Results: The retentive strength for groups A and B were 48.16±12.11 and 61.44±9.16 MPa, respectively. There was significant difference in the retentive strength between group A and B (P<0.05).
Conclusion: It seems that type of cement had effect on the retention of fiber posts. Panavia F2 Kuraray resin cement significantly provided higher retention than that of Starfill 2B Danville cement.
Ali Eskandarizadeh, Shahram Farzin Ebrahimi, Niloofar Shadman, Saeed Rahmani,
Volume 30, Issue 2 (8-2017)
Abstract
Background and Aims: Delay in light irradiance can improve the polymeric structure and mechanical properties of resin cement and uniform stress distribution. The aim of this study was to evaluate the effect of light activation modes (immediate, 5 and 10-minute delay) on the push-out bond strength of cemented fiber posts with two types of resin cements in different of root canal regions.
Materials and Methods: In sixty extractedsingle canal and endodontic therapied roots, FRC Postec Plus were cemented with two resin cements, Nexus3 and Panavia F2.0, in three curing methods, immediate, 5, and 10 minute delay. After 24 hours storing in a dark place, they were cut into three sections: coronal, middle and apical. The push-out bond strength test was performed using the universal testing machine. Failure modes were evaluated using stereomicroscope. Data were analyzed by ANOVA and Tukey post hoc test with P<0.05 as the level of significance.
Results: In Nexus3, the immediate light curing had significantly higher bond strength (11.18±4.32) than delay methods (P=0.001). In Panavia F2.0, the 5-minute delay had significantly the highest bond strength (13.34±4.62) (P<0.05). There was no correlation between the different light curing methods and root canal regions. In Nexus3, the coronal region had higher bond strength (11.83±3.7) than that of middle (9.12±3.1) (P=0.015), and middle than of apical (5.65±2.77) (P=0.00), and coronal than that of apical (P=0.002). In Panavia F2.0, there were not significant differences among regions (P>0.05).
Conclusion: Delay in light curing of dual-cure resin cement's had different effects on the push-out bond strength.
Mohammad Hosain Lotfi Kamran, Mahnaz Hatami, Abbas Fallah Tafti, Mohammad Malekzadeh,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: To create a good adhesion between porcelain veneers and zirconia restorations has been important issues is the prosthesis. The aim of this study was to identify an effective way to prepare the zirconia surface infrastructure to increase its shear bond strength to the porcelain veneer.
Materials and Methods: 75 samples of zirconia (Y-TZP) cylinders (diameter of 7 mm and a thickness of 3 mm) were fabricated. Based on the surface treatment, specimens were randomly divided into 3 groups: control, air abrasion and
Er-YAG laser. After surface treatment, the specimen surfaces were examined by SEM. Using a metal mold, the porcelain was veneered on the zirconia surface and then fired. After thermocycling, the shear bond strength of porcelain to zirconia was measured and then the failure mode of each specimen was analyzed using a stereo-microscope. Data were analyzed by one-way ANOVA and Tukey test.
Results: Significant differences were observed between the mean shear bond strength of different groups (P=0.001). The greatest amount of shear bond strength was observed in the group (S) and the lowest bond strength in the control group. Analysis of failure modes showed no statistically significant difference in the type of failure among study groups. The adhesive failure was predominating failure at the intersection of porcelain veneers.
Conclusion: The highest shear bond strength between zirconia and porcelain was achieved by sandblasting the zirconia surfaces compare with that of Er_YAG application.
Rahim Asghari Salavat, Ahad Samadi,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: Poor adhesion between porcelain and some of the dental alloys is one of the most challenges to select the desirable alloy in dental restorations. Therefore, the aim of this study was to evaluate the bond strength of porcelain to some of the commercial alloys. This can help in selection of desirable alloy.
Materials and Methods: The shear bond strength of porcelain to the three of the most widely used nickel-base dental alloys commercially named as: Verabond, Damcast and Noritake were evaluated according to standard ASTM E4. The results were analyzed based on the statistical method of independent t with the meaningful level of P<0.05. Then, the bonding interface of the fired samples was evaluated using SEM equipped with EDX analyzer and X-ray diffractometry.
Results: The average bonding strength of porcelain to each of the above mentioned alloys were determined as: 27.54±5.48, 22.46±4.99 and 26.18±4.27 MPa, respectively. Due to the existence of Be and Al in the chemical composition of Verabond and Damcast and their higher appetencies to form the different surface oxides in preference to Cr2O3, not only the bond strength of porcelain to two these alloys was increased about 20 percent (compared with the Noritake), but also the color of their porcelain was not changed.
Conclusion: To replace the replacing of deleterious elements from the chemical composition of dental alloys. The added new elements should control through the oxide layer and the formation of Cr2O3 in porcelain-alloy interfaces for adequate bond strength.
Ramin Mosharraf, Aref Sadeghian,
Volume 31, Issue 3 (11-2018)
Abstract
Background and Aims: In endodontically treated teeth, the fiber posts are used to retain a core restoration. The purpose of this study was to evaluate the effect of different resin cements on the bond strength of fiber reinforced composite posts to root canal dentin, and comparing the bond strength in different sections of root.
Materials and Methods: In this in-vitro experimental study, 48 extracted single-canal central incisors were endodontically treated. For the push out test, the posts were divided into 3 groups according to one of the following three different cement materials (n=16) (Bifix SE, Bifix QM, Rebilda). Three slices with a thickness of 2-mm were prepared of each root. The push-out tests were performed at a cross-head speed of 1 mm/minute using a universal testing machine. Data were analyzed by two-way and one-way ANOVA test followed by Tukey post hoc test (α=0.05).
Results: There was no significant differences between the mean push out bond strength of three experimental groups (P=0.650), but there were significant differences between the mean push out bond strength of root dentin regions (P<0.001).
Conclusion: Under the conditions of this study, there was no significant difference between the mean push out bond strength of 3 different resin cement systems. The coronal region of root dentin showed significantly higher mean bond strength values than that of the middle and apical thirds.
Fatemeh Ensafi, Tabassom Hooshmand, Maryam Pirmoradian,
Volume 32, Issue 1 (7-2019)
Abstract
Background and Aims: Today, resin composites are one of the most commonly used materials in restorative dentistry. However, failure in resin treatments is also common due to its chemical nature and its high talent for decay recurrence. According to conservative approaches, "conservative" treatments are more likely to be considered than "Replacement" of damaged remedies. The purpose of this study was to compare different surface preparation methods on composite surfaces to achieve the highest bond strength between the old and new composites after accelerated aging.
Materials and Methods: First, composite cylinders with a diameter of 6 and a height of 5 mm were prepared using an incremental technique and a microhybrid resin composite. The specimens were stored in distilled water for 6 months at 37°C and then the surfaces of all aged compsites were roughened using diamond milling followed by phosphoric acid etching. The specimens were randomly subjected into five groups. Group 1: GC Composite Primer. Group 2: Universal bonding containing silane (Kuraray). Group 3: Self etching adhesive (SE bond; Kuraray) Group 4: silane (Ivoclar Vivadent) + Second bottle of SE bond bonding system (Kuraray). Group 5: control group with no treatment. Then, 5 mm incremental of new composite (similar to the aged composite with different color) were placed on the surfaces of specimens, sectioned, and thermocycled for 3000 cycles for the microtensile bond strength evaluation. The specimens were evaluated using a stereomicroscope after failure. Data were analyzed by one-way ANOVA and Post Hoc Tukey test.
Results: The specimens in which silane and SE bond were used showed the highest mean microtensile bond strength and those treated by universal bond showed the least bond strength which were significantly different (P=0.02). All samples had cohesive failure patterns in all groups and the percentage of failures in old and new composites did not differ significantly (P=0.69).
Conclusion: : Based on the results, all surface preparations used in this study could provide an appropriate bond strength for repair of old composite restorations. Also, the microtensile bond strength between the old and new composites was higher than the cohesive strength of resin composite itself. However, the mean microtensile bond strength value for the group treated by universal bond was significantly lower than those treated by silane and hydrophobic containing bonding system.
Abdolrahim Davari, Alireza Daneshkazemi, Farnaz Frahat, Fatemeh Kohestani,
Volume 32, Issue 1 (7-2019)
Abstract
Background and Aims: Despite patient’s demand increased for tooth color restorations, the stable bond between dentin and composite is a challenge in dentistry. Dentin protease activation is responsible for dentin-resin bond failure. The aim of this study was to determine the best pretreatment agent to inhibit matrix metalloproteinase and increase resin-dentin bond durability.
Materials and Methods: After collecting 24 intact third molars, the dentin surfaces were exposed immediately under DEJ. After acid etching of dentin rewetting was done with CHX 2%, EDC 0.3 M for 60 and water (control group). Then the adhesive (Single bond, 3M ESPE, USA) and composite (Filtek Z250 XT, 3M ESPE, USA) were applied. 48 sectioned dentinal specimens were prepared. The specimens were divided into 3 groups. Each group was divided into 2 sub groups (n=8). In half of each group, the micro tensile bond strength test was done immediately and another part half 6 months. Then, the specimens were evaluated by stereomicroscope and SEM. Statistical analysis was performed using SPSS23 software, two-way ANOVA and multiple Tukey and T-test comparisons. P<0.05 was considered as a significant level.
Results: There were not significant differences between immediate micro tensile bond strength of CHX, EDC and control groups (P=0.97). However, there was significant differences between CHX, EDC compared with the control group (P≤0.0001). Comparison between the immediate and 6-month bond strengths in each group, only in EDC group, there was no significant after 6 months’ difference (P=0.64).
Conclusion: EDC and CHX t did not have any effect on the immediate microtensile bond strength. After 6 months, EDC prevented bond strength deterioration, but the bond strength was decreased after CHX usage.
Sajjad Pezeshki, Saharnaz Hassanzadeh Kourandeh,
Volume 33, Issue 4 (1-2021)
Abstract
Background and Aims: Poly methyl methacrylate (PMMA) is still the most commonly used material in prosthetic dentistry. However, there are problems with the mechanical properties of this type of material including low flexural strength. Addition of nanoparticles into the polymer is one way to improve the mechanical properties of acrylic resin. In the present study, the effect of silicon dioxide (SiO2) nanoparticles addition into the heat-cured acrylic resin in different concentrations was investigated. Because of the controversy had been observed in previous articles, the aim of this study was to investigate the mechanical properties of PMMA/SiO2 nanoparticle obtained from different percentages of SiO2.
Materials and Methods: In this in-vitro study, acrylic resin specimens containing 0, 1, 3 and 5% silicon dioxide (SiO2) were prepared. The specimens were placed inside the gypsum molds and placed under pressure for three times. The mold cured in boiling water for 30 min. A trimmer was used to remove the additives. Sandpapers with 180, 320 and 600 grains of silicon-carbide were used for final finishing and polishing. Finally, the flexural strengths were measured using a universal testing machine. Data were finally analyzed by ANOVA and Tukey tests at a significant level of 5% using SPSS software.
Results: The mean flexural strengths and standard deviations of control group, 1% filler, 3% filler, and 5% filler, were 57.24±8.30, 69.98±7.26, 60.16±9.18, and 61.59±9.28 MPa, respectively. After comparing significant values between each group with the control group, a significant difference was observed between the control and 1% filler group (P=0.021). However, no significant difference was observed between 3 and 5% fillers with the control group or each other. The significant differences (P-value) between 3% filler and control group were 0.892 and between 5% filler and control group was 0.975.
Conclusion: The results of the present study showed that the use of low percentage of silicone dioxide (SiO2) nanofiller could improve the flexural strength of poly methyl methacrylate acrylic resin.
Abdolrahim Davari, Hengameh Zandi, Farnaz Faraahat, Zahra Haddadi,
Volume 34, Issue 0 (5-2021)
Abstract
Background and Aims: Nowadays, new techniques are used to control dental caries that have the ability to kill cariogenic bacteria. Recently, the addition of antibiotics to glass ionomers has been proposed to reduce the overall number of saliva bacteria. The aim of this study was to compare the antimicrobial effect and compressive strength of resin- modified glass ionomer (RMGI) containing different antibiotics on Streptococcus mutans.
Materials and Methods: A total of 120 specimens were prepared in 3 groups (n=40) including RMGI containing doxycycline with a concentration of 1.5%, RMGI containing a combination of ciprofloxacin, metronidazole and minocycline with a concentration of 1.5%, and RMGI without antibiotics as control group. To measure the antibacterial effect, the disk diffusion method and counting of Streptococcus mutans bacterial colonies were used and then the compressive strength test was performed. Data were collected into SPSS25 and analyzed by ANOVA and Kruskal-Wallis tests and the significance level was considered α=0.05.
Results: The mean number of bacterial colonies in the RMGI group containing doxycycline in all three time intervals 1, 24 hours and 7 days was significantly lower than the specimens in the RMGI group containing the triple antibiotic (P<0.001). The mean compressive strength of the two experimental groups was lower than the control group but was not statistically significant (P=0.326).
Conclusion: The addition of antibiotics at a concentration of 1.5% to RMGI resulted in a favorable antibacterial property with no significantly change in the compressive strength.
Abdolrahim Davari, Farnaz Farahat, Sanaz Abbasi,
Volume 34, Issue 0 (5-2021)
Abstract
Background and Aims: Restoration of non-carious cervical lesions (NCCLs) is challenging due to the difficulty of adhesion of dental tissues. The aim of this study was to investigate the effects of three methods of surface treatments using diamond bur, Er: YAG laser and sandblasting on the microtensile bond strength of resin composite to the noncarious dentin in cervical lesions.
Materials and Methods: In this in vitro study, 48 canine and premolar extracted human teeth with NCCLs at the buccal surface were selected and randomly divided into 4 groups of twelve each: control group without any treatment, Er: YAG laser group, diamond bur group and sandblasting group. For all groups, the bonding agent used was Clearfil SE Bond and then the cavities were filled with
the Filtek Z250 resin-composite. After this step, the teeth were cut and then subjected to the microtensile bond strength test. Data were analyzed by the Kruskal Wallis test.
Results: According to the obtained results, the microtensile bond strength, from the highest to the lowest values were in the sandblast group (24.57±10.24 MPa), the diamond bur group (19.19±10.8 MPa), laser group (18.59±9.05 MPa) and the control group (18.56±9.27 MPa), respectively. Although, no statistically significant difference was found between any of the groups (P=0.266).
Conclusion: It seems that in teeth with NCCLs, the sandblasting method had a much better effect on the bond strength, although no statistically difference between surface treatment methods was found.
Abdolrahim Davari, Farnaz Farahat, Mahnaz Mehranfar,
Volume 35, Issue 0 (5-2022)
Abstract
Background and Aims: Recently, the addition of nanoparticles into the restorative materials and tooth preparation by laser for improving the bond strength have been concidered by researchers. The aim of this study was to investigate the shear bond strength of the bioactive glass ionomer containing titanium particles and a conventional glass ionomer with two surface treatments by Er-YAG laser and conventional methods.
Materials and Methods: In this in-vitro study, 64 sound extracted premolars were collected. For conventional method, the specimens were prepared in such a way that dentin surfaces with a depth of 0.5 millimeter created at distance of 2 mm from the joint of CEJ at the root or crown. In the laser group, after preparing the teeth, the surface area was prepared by Er-YAG laser. Then, in the middle part of the buccal surface, a cylindrical mold with dimensions of 3.5 mm in diameter and 4 mm in height was placed and for each group was filled with its own glass ionomers. The specimens were divided into 8 groups by simple random sampling (n=8): A (laser, conventional glass ionomer, coronal dentin)/ B (laser, glass ionomer containing titanium nanoparticle, coronal dentin)/C (conventional, conventional glass ionomer, coronal dentin)/ D (conventional, glass ionomer containing titanium nanoparticle, coronal dentin)/ E (laser, conventional glass ionomer, root dentin)/ F (laser, glass ionomer containing titanium nanoparticle, root dentin)/ G (conventional, conventional glass ionomer, root dentin)/ H (conventional, glass ionomer containing titanium nanoparticle, coronal dentin). Finally, the shear bong strength by a universal testing machine was measured at a cross-head speed of 1 mm/min. For data analysis, Two-way ANOVA test was used to evaluate the effect of each variable and their interaction on the shear bond strength and Tukey test was used to compare the two groups.
Results: There was significant difference only between groups B with C (P=0.002), E (P=0.007), G (P=0.001) and H (P=0.01). The highest bond strength was found for group B (laser, glass ionomer containing titanium nanoparticle, coronal dentin) and the lowest bond strength for group G (conventional, conventional glass ionomer, root dentin).
Conclusion: All three factors of Er-YAG laser, glass ionomer containing titanium nanoparticle and coronal dentin had a positive effect on the improvement of the bond strength.
Abdolrahim Davari, Farnaz Farahat, Haleh Davoudi,
Volume 36, Issue 0 (5-2023)
Abstract
Background and Aims: Insufficient adhesion between fiber post and root canal is the main reason for the failure of the restoration and the fiber post surface treatment can imprive the bond strength. Additionally, there is disagreement about the ideal method of preparation to achieve the desired bond. The aim of this study was to compare the effect of two surface treatment methods on push-out bond strength of fiber posts to root canals.
Materials and Methods: In this study, 45 healthy incisor teeth underwent root canal treatment. After preparing the post space, they were divided into 3 groups of 15, based on the surface treatment methods of the fiber post. In the first group as control group, no surface treatment was done on the fiber post. In the second and third groups, sandblasting with Cojet sand particles and 810 nm diode laser were used for surface treatment, respectively. Then, fiber posts were placed in all root channels by a self-adhesive resin cement. Then, the roots were cut in such a way that from each, 3 pieces with a thickness of 1.5 mm were obtained. Finally, the push-out bond strengths were measured using a universal testing machine. Data were analyzed by ANOVA using SPSS software. The level of significance was considered at P<0.05.
Results: The average bond strengths in three groups were as follows: control group, 2.877 ±1.430, sandblast group 6.318±3.444, and laser 4.224 ±1.890 MPa ± SD. The difference in the bond strength between the sandblast group and the control group was significant (P=0.001). However, the average of the bond strength of laser group was not significantly different from the control group. (P=0.03).
Conclusion: The findings of this study showed that unlike diode laser radiation, the use of Cojet sand particles for sandblasting the fiber post surfaces significanlty improved the bond strength.
Maryam Saadat, Marzieh Moradian, Zahra Akbari, Parisa Ghodati,
Volume 37, Issue 0 (3-2024)
Abstract
Background and Aims: The bond strength of direct composite restoration to the caries affected dentin is a challenging issue. Preparation of dentin with an antibacterial agent is a method for creating durable bonded restorations. The aim of this study was to investigate the effect of curcumin photosensitizer on the bond strength of a universal adhesive to the caries-affected dentin (CAD).
Materials and Methods: In this experimental in vitro study, forty-four decayed human molar teeth were selected. After removing the surface enamel and dentin by a water-cooled saw, the decayed mid-coronal dentin was stained with a caries detection solution. The green and soft infected dentin was removed and CAD and hard and healthy surrounding dentin were left. Then, the remaining dentin surfaces were treated by 600 grit silicon carbide papers and polished. The specimens were divided into two groups (n=22): dentin pretreatment group by curcumin and control with no dentin pretreatment group by curcumin. Each group was divided into two subgroups based on the method of application of All-Bond Universal adhesive (Bisco, USA) (etch and rinseand self-etching methods). After placing the Aelite All Purpose Body (Bisco, USA) composite, all specimens were placed in a universal testing machine for microshear bond strength (µSBS) test. The failure mode of the isolated surfaces was evaluated under a stereomicroscope. Two-way ANOVA analysis was used for statistical analysis.
Results: Based on the obtained results, intervention with the adhesive application method and surface pretreatment with curcumin had no significant effect on the bond strength. Also, there was no significant difference in the bond strength of the curcumin group in both etch and rinse and self-etching methods (SE=56.3±27.11 MPa; ER=52.4±84.11 MPa) (P=0.847). In the curcumin-free group, there was no significant difference between the two different adhesive application methods (P=0.187).
Conclusion: The results obtained in the present study showed that the pretreatment of dentin affected by caries with light-sensitive curcumin and also use of a universal adhesive by either self-etching or self-etchinf methodshad no influence on the microshear bond strength of the composite restoration.
