Nanofilled Resin Composite Research Articles

Under-surface hardness of light-cured nanofilled resin composites of different shades

The objective of the this study was to analyze the under-surface hardness of light-cured nanofilled composite resins of different shades. The specimens were resin composites of each light (B1), medium (A3), and dark (C3) shades packed in a cylinder mold and subsequently polymerized. The hardness was tested using a Knoop system. The hardness test results for the bright (B1), medium (A3), and dark (C3) shades were 82.4+1.1, 75.9+1.2 and 65.9+1.9, respectively, and indicated significant differences between the under-surface hardness of each shade. It was concluded that resin composites of darker to brigher shades demonstrated lower to higher under-surface hardness.

Comparison of surface roughness of nanofill and nanohybrid composite resin polished by aluminum oxide and diamond particle paste

Introduction: The adequate finishing and polishing procedures might occur the restoration longivity, the color retention, and the good integrating with the surrounding environment. Methods: This study was conducted to determine the surface roughness of the nanofill composite with the nanohybrid composite polished by the aluminum oxide pastes and diamond polishing paste. This study was a pure experimental-in vitro study. The results of polishing on the resin composite surfaces was observed using the optical microscope at 500x magnification and given the score. The Krusskal-Wallis test was conducted to depict the data analysis. Result: The results showed that the resin composite group of the nanohybrid polished by both aluminum oxide and diamond particle had smoother surface than the resin composite of the nanofill. Conclusion: The conclusions of this study depicted that there were differences of polishing results using the aluminium oxide and diamond particle paste between the nanofill and nanohybrid resin composite surface roughness.

COMPRESSIVE STRENGTH AND SURFACE ROUGHNESS OF CERAMIC REINFORCED GLASS IONOMER SUBJECTED TO CHEMICAL CHALLENGE

Objective: This research was conducted to investigate the effect of chemical challenge on the compressive strength (CS) and surface roughness (Ra) of a ceramic reinforced glass ionomer in comparison to a nanofilled resin composite. Methods: A total of 60 disc specimens (6mm height x 4mm diameter) were prepared for the compressive strength testing and another 60 disc specimens (5mm diameter x 2mm thickness) for the surface roughness testing. Specimens were divided into 2 groups (n=30) according to the material used; ceramic reinforced glass ionomer (Amalgomer CR, Advanced Health Care Ltd, Tonbridge, Kent, UK) and nanofilled resin composite (FiltekTM Z350 XT, 3M ESPE, St.Paul, MN,USA). Each group was divided into 3 subgroups (n=10) according to the storage media; distilled water (control), 0.02N citric acid and 50% ethanol. Specimens were stored for 7 days at 37oC. After storage period, they were subjected to compressive loading using a universal testing machine and surface roughness testing using white light interferometer. Data were tabulated and statistically analyzed using Two-way ANOVA followed by Bonferroni’s post-hoc test.Results: Amalgomer CR recorded a significantly lower CS and higher Ra than nanofilled resin composite under different storage media. Citric acid revealed the lowest CS of Amalgomer CR followed by ethanol in comparison to distilled water with significant difference between them. For nanofilled resin composite, both citric acid and ethanol significantly decreased CS. Ethanol showed the highest Ra values for both restorative materials. Conclusions: The performance of Amalgomer CR under different storage media was inferior to nanofilled resin composite regarding compressive strength and surface roughness. Citric acid severely affected compressive strength of Amalgomer CR. Nanofilled resin composite was able to preserve its surface roughness within the clinically acceptable threshold after chemical challenge in contrary to Amalgomer CR.

Effect of bench time polymerization on depth of cure of dental composite resin

The aim of this research was to investigate the effect of bench time before light cured polymerization on the depth of cure of dental composite resin. Nanofiller composite resin (Filtek Z350 XT,3M, ESPE,China) was used in this study. Sixty samples of nanofiller composite resin were made and divided into control and test groups with bench time for 0, 15, 30, 45, and 60 min. For the test group, composite resins were stored in refrigerator with 4°C temperatures. Meanwhile, for the control groups, the composite resin was stored at room temperature. The samples were prepared using metal mould with size diameter of 6 mm and 4 mm in thickness. Samples were cured for 20 s by using visible blue light curing unit. Part of samples that unpolymerized were removed by using a plastic spatula. The remaining parts of samples were measured by digital caliper and noted as depth of cure (mm). Data were analyzed to one-way ANOVA and LSD tests (p≤0.05). Results showed there was no significance differences between test groups (p=0.5). A 60 minutes bench time group showed the highest depth of cure value among test group, and it was almost similar with control group value. It can be concluded that longer bench time can increase the depth of cure of composite resin.

KEKASARAN PERMUKAAN RESIN KOMPOSIT NANOFILLER SETELAH PERENDAMAN ALAM AIR SUNGAI DAN AIR PDAM

ABSTRACT Background :One of composite resin kinds is often used for tooth restoration, it is nanofilled composite resin. Nanofilled composite resin is a restoration material containing nano size filler particle, so that it can repair the physical characteristic of composite such as reducing the surface roughness. People in Barito Kuala especially in Desa Anjir Pasar, besides using tap water, they also still use water from river for daily use. The water of river in Desa Anjir Pasar has acid characteristic with Ph range 3-5. An acidic environment causes surface roughness of nanofilled composite resin which allow the secunder caries.Purpose : The aim of this research was to know the difference in surface roughness of nanofilled composite resin after being immersed in river water, tap water, and sterile aquades. Method :This research was a true experimental research with post test only and control group design, used nanofilled composite resin disc samples with diameter of 10 mm and 2 mm thick divided into 3 groups of treatment. Each group was immersed in sterile aquades (as control group), tap water, and river water with acid Ph for 8 days (equals to 3 years of exposure), then the surface roughness was measured using surface roughness measurement. Result : Data was tested using parametric analysis one way anova 95% ( = 0,05) and it obtained p = 0,000 (p = < 0,05). Based on the result it can be concluded that there was significant difference in surface roughness on nanofilled composite resin which had been immersed in each water sample for 8 days. Conclusion : Nanofilled resin composite immersed in river water had higher mean value of surface roughness compared to immersion in sterile aquades and tap water. Keywords: Resin Nanofilled Composite, River Water, Tap Water, Surface Roughness

PERBEDAAN PERUBAHAN WARNA RESIN KOMPOSIT NANOFILLER YANG DIPOLES DAN TIDAK DIPOLES PADA PERENDAMAN LARUTAN TEH HIJAU

ABSTRACT Background: One of composite resin kinds isoftenused for tooth restoration,it is nanofilled composite resin. Nanofilled composite resin has one major problem which is color change due to external and internal factors. Finishing and polishing are factors that determine color change and together with consumption of colored beverages in a long period of time, it can cause more significant color change. Green Tea is an herbal tea which is often consumed by people nowadays because it has many benefits. However, composition of green tea can also make restoration to change color. Purpose: Theaim of this research was to know the difference of color change between polished and non polished nanofilled composite resin immersed in greentea solutions. Method: This research was a true experimental research with pretest dan post test with control group design using disc samples with diameter of 10 mm and 2 mm thick divided into 4 groups of treatment which were polished nanofilled composite resin group, non polished group, greentea group, and sterile aquadest group. The samples were immersed in different media for 24 hours per day for 5 days. Color change at each group were measured with optical spectrometer (OPT 101 type of photo detector) and digital microvolt. Statistical tests usedpaired T-test and single T-test with a significance of 0.05. Result: Result of this research showed that there were differences in color change on polished nanofilled composite resin and non polished nanofilled composite resin after being immersed in green tea solutions and sterile aquadest. Keywords: nanofilled composite resin, color change, green tea.

PERBEDAAN PERUBAHAN WARNA RESIN KOMPOSIT NANOFILLER PADA PERENDAMAN AIR REBUSAN DAUN SIRIH MERAH ( PIPER CROCATUM) DAN OBAT KUMUR NON-ALKOHOL

ABSTRACT Background: One of resin composite type is nanofiller. Composite resin has tendency to have color change. One factor that can cause color change on the composite resin as mouthwash. Purpose: To determine the difference of color change between nanofiller composite resin that were immersed in decoction water of red bettel leaves (Piper crocatum) and non-alcohol mouthwash. Method: This study was a true experimental research design with control group design pre-test and post-test. It used disk form sample with 10mm diameters and 2mm of thickness. Total samples were 24, divided into 3 treatment groups immersed in decoction water of red bettel leaves (Piper crocatum), non-alcohol mouthwash and sterile aquadest within 24 hours in the incubator with temperature of 37C. Samples were examined by using optical spectrometer (OPT 101 type of photo detector) and microvolt digital. The statistical test was using One-way ANOVA and Post Hoc Bonferroni with <0.05 significance. Result: The result of this study showed significant color change on nanofiller composite resin after immersion in decoction water ofred bettel leaves (Piper crocatum) and non-alcohol mouthwash. Mean value of color change of resin composite immersed in aquadest (0,15Mv), non-alcohol mouthwash (0,24 Mv) and decoction water of red bettel leaves (Piper crocatum) (0,34Mv). Conclusion: There were difference of color change between nanofiller composite resin using the decoction water of red bettel leaves (Piper crocatum) and non-alcohol mouthwash. It showed that composite resin immersed in decoction water of red bettel leaves (Piper crocatum) had higher color change. Keywords : Resin composite nanofiller, color change, mouthwash

COMPARISON OF SHEAR BOND STRENGTH OF METAL AND CERAMIC ORTHODONTIC BRACKETS AFTER ADDING NANOPARTICLES OF SILVER

Objective: To evaluate effect of nanoparticles of silver (NAg) added on Nano-Bond adhesive system and its effect on shear bond strength of brackets attached to enamel. Materials and methods: Thirty extracted premolar teeth for orthodontic reasons were divided into two groups; First group metal brackets and second group the ceramic brackets were bonded by Nano-Bond adhesive system containing (NAg) with concentration 0.05%. Every group was further subdivided into 2subgroups with 5 teeth each; Groups A1, B1 (Teeth not subjected to thermocycling and cyclic loading), Groups A2, B2 [(Teeth subjected to thermocycling (500cycles) and cyclic loading (90N, 0.8-1 cycles/sec. 100,000 cycles)]Enamel etched then the adhesives were applied to the entire enamel surface according to bonding agent containing (NAg) or not, then light cured for 10 seconds with LED. The base of brackets were filled by nano-filled composite resin and placed on the tooth and cured by LED for 40 seconds. The recorded values of bond strengths in (MPa) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05.Results: shear bond strength of metal brackets bonded by Nano-Bond adhesive containing nanoparticles of silver (NAg) (Group A) was significantly higher than shear bond strength of ceramic brackets (group B).Conclusions: The adhesive shear strengths are high for metal bracket bonded by Nano-Bond adhesive system containing nanoparticles of silver (NAg) with concentration 0.05% than ceramic bracket.

Color Stability Assessment of Two Different Composite Resins with Variable Immersion Time Using Various Beverages: An In vitro Study.

Purpose of the Study:The aim of the study was to evaluate the difference in the color of microhybrid (MH) and nanofilled (NF) composite resins after 24 and 48 h in beverages such as red wine (RW), Coca-Cola, and distilled water. The specific objective of this study was to investigate the cumulative effect of the colorant solutions on the dental composites.Materials and Methods:MH and NF composite resins (A2 shade) were used in this current study. Sixty disk-shaped material specimens (10 mm in diameter × 2 mm in thickness) were prepared using a fiber mold (ring), with the desired dimensions. The specimen surfaces were polished using super-snap polishing system. Sixty specimens were divided into two groups of 30 each (Group I: MH resin composite; Group II: NF resin composite). Both the groups divided into six subgroups (Subgroup I: RW for 24 h [RW-24]; Subgroup II: RW for 48 h; Subgroup III: Coca-Cola for 24 h [CC-24]; Subgroup IV: Coca-Cola for 48 h [CC-48]; Subgroup V: Distilled water for 24 h [DW-24]; Subgroup VI: Distilled water for 48 h [DW-48]). All the samples were immersed in respective drinks for a period of 24 h, and color differences were measured using ultraviolet spectrophotometer. Once again, all the samples were immersed for another 24 h in the same drinks. After 48 h, the color change of the samples was measured. Measurements were made according to the CIE L × a × b × color space relative to the CIE standard illuminant D65. The color changes of the specimens were evaluated using the following formula: Statistical analysis was performed. The data were analyzed using the one-way ANOVA and t-test at a significance level of 0.05.Conclusion:Color stability of MH composite resin was found to be inferior than the NF resin composite irrespective of immersion medium and time. In RW, the color change observed was maximum for both composite resins followed by Coca-Cola. Immersing the resin composites in distilled water for 24 and 48 h had negligible color change. A 48-h immersion of both composite resins in all three immersion mediums showed greater color change than 24 h immersion.

Influence of Curing Light Type and Staining Medium on the Discoloring Stability of Dental Restorative Composite

Discoloration kinetics of 4 commercial nano-filled resin composites polymerized with LED and QTH source types in 4 different staining media held at 37°C are investigated. Quartz Tungsten Halogen (QTH) and Light Emitting Diode (LED) were used. Dental composites color change was monitored with a digital spectrophotometer at one, two and four weeks for quantitative comparison. The kinetics and intensities of the color change in accelerated aging tests in staining media were monitored and discussed. Discoloring followed diffusive driven kinetics. The four composites polymerized with QTH light showed higher differences in color change intensities compared to LED cured ones. All the QTH cured samples have shown significant higher variations of color changes intensities compared to LED samples (p<0.05). LED cured composite showed comparatively more stable initial shade persistence than QTH cured ones, which may be explained in terms of higher level of polymerization and surface hardness reached by the LED light cure resinous composite matrix.

English

English

PERBEDAAN KEKERASAN PERMUKAAN BAHAN RESTORASI RESIN KOMPOSIT NANOFILLER YANG DIRENDAM DALAM MINUMAN RINGAN BERKARBONASI DAN MINUMAN BERALKOHOL

Resin composite is dental material filling that is commonly used in dentistry which has good physical properties, mechanical and aesthetics. The properties that have an important role in the resistance of the composite resin surface hardness which directly involved when contact with food, drink and salivary. The purpose of this research is to evaluate the effect of carbonated soft drink and alcoholic beverages on the surface hardness of nanofiller composite resin.The method used in this research is post test only control group design. Samples were made using the mold made of stainless steel, with diameter of 6mm and tick of 2mm, composite was manipulated according to the manufacture’s instructions, and then immersed in aquades, carbonated soft drink and alcoholic beverages for 18 hours in a temperature of 37ºC. Samples were tested using Vickers Hardness Test. Data analysis using Kruskal-Walis test.The result show that the nanofiller composite resin which immersed in alcoholic beverages has higher surface (81,04±10,44 VHN), whreas the composite which immersed in aquades and carbonated soft drink has the surface hardness (70,20±16,6 dan71,10±15,96 VHN). The result of data analysis showed that the data are not distributed normally and showed a significant value of p&gt;0,05. From this research can be concluded that there is no significant differences in surface hardness of nanofiller composite resin which immersed in carbonated soft drink and alcoholic beverages.&#x0D; Keywords: Resin Komposit, nanofiller, surface hardness, mechanical properties.

Influence of Battery Level of a Cordless LED Unit on the Properties of a Nanofilled Composite Resin.

The properties of composite resins can be influenced by light activation, depending primarily on the performance of the curing unit. The aim of this study was to evaluate how different battery levels of a cordless light-emitting diode (LED) unit influence the properties of a nanofilled composite resin. First, the battery voltage and light intensity of the cordless LED unit were individually checked for all light-curing cycles. Then, composite resin discs were prepared and light-cured at different battery levels: high level (HL, 100%), medium level (ML, 50%), and low level (LL, 10%). The degree of conversion, diametral tensile strength, sorption, and solubility of the specimens were tested. Data were checked for homoscedasticity and submitted to one-way analysis of variance followed by Tukey honestly significant difference and Pearson correlation tests (p<0.05). The battery voltage and light intensity varied significantly among the groups (p<0.001). The LL group presented a lower degree of conversion than the HL and ML groups (p<0.001), which shower similar results (p=0.182). Lower diametral tensile strength was also verified for the LL group when compared with the HL and ML groups (p<0.001), which presented no difference (p=0.052). Positive correlation was observed between the light intensity and the parameters studied, with the exception of sorption and solubility (p<0.001). The ML and LL groups showed higher sorption than the HL group (p <0.001), but no difference was verified between the first two groups (p=0.535). No significant differences were found for solubility between the ML and LL groups (p=0.104), but the HL group presented lower values (p<0.001). The different battery levels of the cordless LED curing unit influenced all the properties of the nanofilled composite resin evaluated.

EFFECT OF LIGHT EMITTING DIODE (LED) VERSUS HALOGEN PHOTO- POLYMERIZATION ON SHEAR BOND STRENGTHOF THREE TYPES OF RESIN COMPOSITES

Objective: This study investigated the effect of light emitting diode (LED) and halogen (QTH) photopolymerization on shear bond strength of three types of resin composites. Materials and methods: Sixty molars were selected and randomly assigned into 6 groups. The materials used were: Hybrid resin composite, nano-filled resin composite and silorane based resin composite. The analyzed resin composites were polymerized either by LED or halogen curing sys- tems. After 24 hours storage in distilled water the specimen was submitted to push-out shear bond strength testing using a universal testing machine at cross head speed of 0.5mm/min. one debonded representative specimen of each tested group was examined using an environmental scanning elec- tron microscope to determine the mode of failure. Results: All the specimens cured by LED demonstrated higher shear bond strength than those cured by QTH. There was no statistically significant difference between the two light curing units (LCUs) except for nano-filled resin composite that showed a significant difference. Silorane based resin composite groups were statistically significant higher than nano-filled and hybrid resin com- posites groups. While nano-filled resin composites was statistically non-significant higher than hy- brid resin composite groups. Conclusions: (1) The light emitting diode is effective as halogen curing light to obtain resin- composite with shear bond strength of no significant difference. (2) The silorane-based resin-com- posite restorative material is promising material regarding bonding efficiency to dentin. Recommendation: It is advised to cure nano-filled resin composite with light emitting diode (LED) to obtain higher shear bond strength to dentin

Surface roughness and erosion of nanohybrid and nanofilled resin composites after immersion in red and white wine

Aims:This study aimed to investigate the effects of red and white wine on the surface roughness and erosion of nanohybrid and nanofilled resin composites.Materials and Methods:Sixty specimens of each resin-based composite (RBC) were prepared. Before immersion, baseline data roughness values were recorded using a profilometer. Three groups of discs (n = 20) were then alternately immersed in red wine, white wine, and deionized water (as a control) for 25 min and artificial saliva for 5 min over four cycles. The specimens were then stored in artificial saliva for 22 h. This process was repeated for 5 days following immersion in artificial saliva for 2 days. Subsequently, the process was repeated. After immersion, the specimens were evaluated and data were analyzed by two-way repeated analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) (α = 0.05).Results:Red wine caused significantly greater roughness and erosion than did white wine and deionized water (P < 0.05). Nanohybrid resin composites were significantly rougher than nanofilled resin composites (P < 0.05).Conclusion:The effects of red and white wine on the surface roughness and erosion of resin composite restorative materials depended upon the physical and chemical composition of the restorative materials and the types of wine.

Effect of the Purple Corn Beverage "Chicha Morada" in Composite Resin during Dental Bleaching.

During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3).

EROSIVE AND ABRASIVE POTENTIALS OF SOFT DRINKS AND AIR POLISHING ON NANO-FILLED COMPOSITE RESIN

introduction: Erosion is a common condition that is related to consumption of acidic food and drinks such as; carbonated drinks and fruit juices that might cause early deterioration of the dental restorations. Abrasion of dental restorations might result from physical factors such as tooth brushing or polishing. objective: This study aimed to assess the combined erosive potential of cola soft drink and orange juice, and the abrasive potential of air-polishing, on the surface of nano-filled composite resin restorations via evaluation of microhardness and surface roughness. materials and methods: A total of 60 specimens were prepared from nano-filled composite resin. Specimens were divided into 3 groups according to the immersion media (water, cola, orange juice), and each was further subdivided into 2 subgroups (unpolished or polished). Surface hard- ness was measured using a digital micro-hardness tester, and surface roughness was recorded using a profilometer. Data were analyzed by one-way analysis of variance (ANOVA) and Tukey’s post hoc test. results: A significant decrease in surface hardness was observed on immersion of nano-filled composite in either cola or orange juice. Except for the control group, the air-polished specimens had significantly higher surface hardness when compared to the unpolished ones. Cola and orange juice had a significant roughening effect on composite resin surface. Further increase in Ra values was recorded after air-polishing of both groups. Conclusion: Combining beverages immersion with air-polishing may have a profound effect on the surface deterioration of nano-filled composite resin

EFFECT OF DIFFERENT REPAIR PROTOCOLS ON BOND STRENGTH TO DIRECT AND INDIRECT RESIN COMPOSITE

Objective: This study was carried out to investigate the effect of different surface treatment protocols on bond strength of nano-composite as a repair material to two types of resin composite either direct composite or indirect resin composite blocks for CEREC system. Materials and methods: Total of 80 composite discs were prepared and were divided into two main groups (40 each) according to the type of composite used (C), nano-filled composite (C1) and composite blocks for CEREC system (C2). All specimens were aged for one month in a distilled water solution at 370C. Each group was sub-divided into four subgroups (10 each) according to the surface treatment protocol (T) that was done on the discs, either no treatment (T0) (control), application of Ortho phosphoric acid (T1), Hydrofluoric acid (T2) and Sandblasting(T3) . Each sub group was subdivided into two classes (5 each) according to silane application (S1) or without (S0). Nanofilled resin composite (Filtek Z350 XT, 3M ESPE) was used as a repair material. Microshear bond strength testing (μ-SBS) was done using Universal testing machine. Failure modes of the fractured specimens were analyzed using scanning electron microscope (SEM). μ-SBS results were analyzed using ANOVA, Tukey’s post-hoc and Student t-tests. Results: The indirect resin composite of the hydrofluoric acid group with silane showed the highest µ-Shear bond strength mean value (31.35±5.1) while the direct composite of the etchant group with no silane showed the lowest µ-Shear bond strength mean value (20.8±4.5). Regarding the composite type, C2 recorded statistically significant (P 0.05) highest µ-shear bond strength mean value (26.72±0.78 MPa) followed by T1 (25.77±2.55 MPa) then T2 (24.71±1.44 MPa) while T0 recorded statistically non- significant (P>0.05) lowest µ-shear bond strength mean value (24.54±1.7 MPa). Regarding the silane application, S1 recorded statistically non-significant (P>0.05) higher µ-shear bond strength mean value (26.28±1.57MPa) than S0(24.59±1.66MPa). Conclusions: The Cojet treatment of the resin composite improved the bond strength of different types of resin composite .The type of resin composite used for repair influences the bond strength to the repaired resin composite. Silane application to repaired resin composite affects the bond strength to it with different treatment protocols.

Color stability of nano-filled, micro-hybrid, and silorane-based dental composite resin materials

Aim: The purpose of this study was to investigate the color stability of nano-hybrid, micro-hybrid, and silorane-based composite resin restorative materials upon exposure to staining agents. Materials and Methods: One hundred twenty composites samples were prepared, 40 from each composite material (Filtek ® Z350, Filtek ® P90, and Filtek ® Z250). The specimens were randomly divided into four groups (10 of each sample). The specimens were incubated for 24 h in distilled water and then for 72 h in corresponding mediums (distilled water, red grape juice, green tea, coffee). The color of all the specimens was assessed before and after exposure with a spectrophotometer and total color change (ΔE) was calculated using ΔE* = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2. The data were analyzed with one-way analysis of variance (ANOVA) and Kolmogorov-Smirnov and the means of the solutions were compared by Tukey's honestly significant difference (HSD) (P Result: The lowest dicoloration was observed in Filtek ® LS P90 but it was not significant while the most discoloration was observed in Filtek ® Z350 and Filtek ® Z250. Also, coffee showed a highly significant (P > 0.05) discoloration compared with other media. Conclusions: Within the limitations of this study, it may be concluded that silorane-based composites are more resistant to discoloration than bis-GMA-based composites and coffee had the highest effect on composite discoloration compared to other media.

Effect of hyperbaric oxygen profiles on the bond strength of repaired composite resin.

Objective:This study was performed to evaluate the bond strength of repaired three types of composite resins under various hyperbaric oxygen (HBO) profiles with various session numbers.Materials and Methods:Sixty specimens of three types of composite resin (nanofilled composite, nanohybrid composite and microfilled composite) each type of composite was divided into four group according to various profiles of HBO treatment (control, 2bar, 3 bar and 5 bar). Then, the specimens were repaired; thermocycled, the tensile bond strength were measured. Then the data were analyzed by One-way ANOVA followed by Tukey's post hoc test (α = 0.05).Results:The highest bond strength was obtained for the repaired nanofilled composite resin specimens while; the lowest bond strength was obtained for the repaired microfilled composite resin specimens. The highest tensile bond strength was recorded for the specimens who treated with the highest pressure of HBO.Conclusion:The bond strength of repaired nanofilled composite resins is better than the other types of composite resin. The highest pressure of HBO, the highest bond strength of repaired composite resins.