scholarly journals In Vitro Cytotoxicity of Self-Adhesive Dual-Cured Resin Cement Polymerized Beneath Three Different Cusp Inclinations of Zirconia

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Chang-Yuan Zhang ◽  
Yi-Ling Cheng ◽  
Xin-Wen Tong ◽  
Hao Yu ◽  
Hui Cheng
Keyword(s):  
In Vitro Cytotoxicity ◽  
Resin Cement ◽  
Curing Time ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Extract Solution ◽  
Significant Difference ◽  
Light Curing ◽  
Post Hoc

The aim of the present study was to evaluate the in vitro cytotoxicity of self-adhesive dual-cured resin cement (SADRC) polymerized beneath three different cusp inclinations of zirconia with different light curing time. A commercial SADRC (Multilink Speed) was polymerized beneath zirconia (ZrO2) with three different cusp inclinations (0°, 20°, and 30°) for 20 s or 40 s. After being stored in light-proof box for 24 h, the ZrO2-SADRC specimens were immersed in DMEM for 72 h and then we got the extract solution, cultured the human gingival fibroblasts (HGF, 8 × 103 per well) with 100% or 50% concentrations of the extract solution for 24 h, 72 h, and 120 h, respectively, and evaluated cytotoxicity of the polymerized SADRC with CCK-8 assay in optical density (OD) values, relative growth rates (RGR), and cytotoxicity grades. Statistical analysis was conducted using a two-way ANOVA followed by post hoc Student–Newman–Keuls test. The OD values varied from 0.8930 to 3.2920, the RGR varied from 33.93% to 98.68%, and the cytotoxicity grades varied from 0 to 2. There was significant difference in the OD values among the different cusp inclinations of zirconia (P < 0.001), and there was significant difference in the OD values between the different light curing times in some situations (P < 0.05). The cusp inclination of zirconia affects the in vitro cytotoxicity of SADRC. Prolonging the light curing time from 20 s to 40 s can reduce the in vitro cytotoxicity of SADRC when the cusp inclination of zirconia is smaller than 20°.

The Effect of Different Light-Curing Methods on Temperature Changes of Dual Polymerizing Agents Cemented to Human Dentin

2008 ◽  
Vol 9 (2) ◽  
pp. 57-64 ◽  
Author(s):  
Nadia Malek Taher ◽  
Yousra Al-Khairallah ◽  
Sheikha Hamed Al-Aujan ◽  
Maha Ad'dahash
Keyword(s):  
Resin Cement ◽  
Luting Cements ◽  
Temperature Changes ◽  
Luting Cement ◽  
Significant Difference ◽  
Human Dentin ◽  
Curing Methods ◽  
Light Curing ◽  
Recorded Temperature

Abstract Aim This in vitro study aims to measure the temperature changes of resin luting cements cemented to human dentin when using different light curing systems for photo-activitation. Methods and Materials The three different types of light-curing units (LCUs) used for photoactivation were quartz-tungsten halogen (QTH), light emitting diode (LED), and plasma arc (PAC). Two types of dual cure resin cements were used [Variolink II™ (VL) and Choice™ (CH)]. Feltik Z250™ composite resin material was used to prepare composite discs. Thirty human dentin specimens were prepared for each resin luting cement (ten for each light source). A total of 60 specimens were fabricated. Resin cement was applied on a dentin bridge and covered with the prepared composite disc where specimens were fabricated. Temperature change was recorded with a digital thermometer. Results: The lowest temperature was recorded when VL and CH were photo-activated with the PAC unit. The PAC unit produced significantly lower recorded temperatures than the LED and QTH units. No significant difference appeared between QTH and LED units in terms of recorded temperature. Results The lowest temperature was recorded when VL and CH were photo-activated with the PAC unit. The PAC unit produced significantly lower recorded temperatures than the LED and QTH units. No significant difference appeared between QTH and LED units in terms of recorded temperature. Conclusion The PAC unit produced significantly lower temperature changes compared to QTH and LED curing units. The risk for temperature rise should be taken into consideration during photo-polymerization of adhesive resins with LED or QTH in deep cavities when dentin thickness is 0.5 mm. Citation Taher NM, Al-Khairallah Y, Al-Aujan SH, Ad'dahash M. The Effect of Different Light-Curing Methods on Temperature Changes of Dual Polymerizing Agents Cemented to Human Dentin. J Contemp Dent Pract 2008 February;(9)2:057-064.

Development of a Cavity Disinfectant Containing Antibacterial Monomer MDPB

2016 ◽  
Vol 95 (13) ◽  
pp. 1487-1493 ◽  
Author(s):  
N. Hirose ◽  
R. Kitagawa ◽  
H. Kitagawa ◽  
H. Maezono ◽  
A. Mine ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bond Strength ◽  
Bacterial Species ◽  
Oral Bacteria ◽  
Resin Cement ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Significant Difference ◽  
Adhesive Resin Cement

An experimental cavity disinfectant (ACC) that is intended to be used for various direct and indirect restorations was prepared by adding an antibacterial monomer 12-methacryloyloxydodecylpyridinum bromide (MDPB) at 5% into 80% ethanol. The antibacterial effectiveness of ACC and its influences on the bonding abilities of resin cements were investigated. To examine the antibacterial activity of unpolymerized MDPB, the minimum inhibitory and bactericidal concentrations (MIC and MBC) were determined for Streptococcus mutans, Lactobacillus casei, Actinomyces naeslundii, Parvimonas micra, Enterococcus faecalis, Fusobacterium nucleatum, and Porphyromonas gingivalis. Antibacterial activities of ACC and the commercial cavity disinfectant containing 2% chlorhexidine and ethanol (CPS) were evaluated by agar disk diffusion tests through 7 bacterial species and by MIC and MBC measurement for S. mutans. The effects of ACC and CPS to kill bacteria in dentinal tubules were compared with an S. mutans–infected dentin model. Shear bond strength tests were used to examine the influences of ACC on the dentin-bonding abilities of a self-adhesive resin cement and a dual-cure resin cement used with a primer. Unpolymerized MDPB showed strong antibacterial activity against 7 oral bacteria. ACC produced inhibition zones against all bacterial species similar to CPS. For ACC and CPS, the MIC value for S. mutans was identical, and the MBC was similar with only a 1-step dilution difference (1:2). Treatment of infected dentin with ACC resulted in significantly greater bactericidal effects than CPS ( P < 0.05, analysis of variance and Tukey’s honest significant difference test). ACC showed no negative influences on the bonding abilities to dentin for both resin cements, while CPS reduced the bond strength of the self-adhesive resin cement ( P < 0.05). This study clarified that the experimental cavity disinfectant containing 5% MDPB is more effective in vitro than the commercially available chlorhexidine solution to eradicate bacteria in dentin, without causing any adverse influences on the bonding abilities of resinous luting cements.

scholarly journals Effect of Light-Sources and Thicknesses of Composite Onlays on Micro-Hardness of Luting Composites

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6849
Author(s):  
Francesco De Angelis ◽  
Mirco Vadini ◽  
Mario Capogreco ◽  
Camillo D’Arcangelo ◽  
Maurizio D’Amario
Keyword(s):  
High Power ◽  
Resin Composite ◽  
Composite Layer ◽  
Resin Cement ◽  
Specimen Thickness ◽  
Light Sources ◽  
Curing Time ◽  
Resin Cements ◽  
Halogen Light ◽  
Light Curing

The aim of this study was to compare three different light-curing-units (LCUs) and determine their effectiveness in the adhesive cementation of indirect composite restorations when a light-curing resin cement is used. Two resin composites were selected: Enamel Plus HRI (Micerium) and AURA (SDI). Three thicknesses (3 mm, 4 mm and 5 mm) were produced and applied as overlays and underlays for each resin composite. A standardized composite layer was placed between underlay and overlay surfaces. Light curing of the resin-based luting composites was attained through the overlay filters using LCUs for different exposure times. All specimens were allocated to experimental groups according to the overlay thickness, curing unit and curing time. Vickers Hardness (VH) notches were carried out on each specimen. Data were statistically evaluated. The curing unit, curing time and overlay thickness were significant factors capable of influencing VH values. The results showed significantly decreased VH values with increasing specimen thickness (p < 0.05). Significant differences in VH values were found amongst the LCUs for the various exposure times (p < 0.05). According to the results, a time of cure shorter than 80 s (with a conventional quartz–tungsten–halogen LCU) or shorter than 40 s (with a high-power light-emitting diode (LED) LCU) is not recommended. The only subgroup achieving clinically acceptable VH values after a short 20 s curing time included the 3 mm-thick overlays made out of the AURA composite, when the high-power LED LCU unit was used (VH 51.0). Composite thickness has an intense effect on polymerization. In clinical practice, light-cured resin cements may result in insufficient polymerization for high thickness and inadequate times. High-intensity curing lights can attain the sufficient polymerization of resin cements through overlays in a significantly shorter time than conventional halogen light.

scholarly journals The Effect of the Bioactive Glass and the Er:YAG Laser on the Remineralization of the Affected Dentin: A Comparative In Vitro Study

2020 ◽  
Vol 11 (2) ◽  
pp. 160-166
Author(s):  
Mohammad Javad Moghaddas ◽  
Horieh Moosavi ◽  
Sara Yaghoubirad ◽  
Nasim Chiniforush
Keyword(s):  
Bioactive Glass ◽  
In Vitro Study ◽  
Control Group ◽  
Dentinal Tubule ◽  
Glass Ionomer ◽  
Significant Difference ◽  
Post Hoc ◽  
Caries Lesions ◽  
Cavity Floor

Introduction: The purpose of this study was to compare the effect of the bioactive glass, the glass ionomer, and the Erbium YAG laser as liners on the remineralization of the affected dentin. Methods: The present study was conducted on 64 healthy extracted human molars divided into 4 groups, 1 control group and 3 experimental groups. After artificially inducing dentinal caries lesions, each of the experimental groups was applied to the cavity floor and then restored with a composite. The samples were stored after thermocycling in an incubator for two months. Finally, the hardness of the cavity floor was measured at 3 depths of 20, 50 and 100 μm by the Vickers microhardness tester. The dentin conditions underneath the liners were also evaluated with FESEM. Statistical analysis was performed by two-way ANOVA and the post-hoc Games-Howell test (P<0.05). Results: Among the groups, the lowest microhardness value was in the control group (P<0.05) except at a depth of 100 μm; therefore, there was no significant difference between the control group and the bioactive glass (P>0.05). The laser group had the highest microhardness value, which was significantly different from the control group (P<0.05). There was a significant difference between the laser and bioactive glass (P<0.05), except at a depth of 20 μm. The laser and glass ionomer had only a significant difference at a depth of 100 μm (P<0.05). The microhardness value induced by glass ionomer was higher than bioactive glass, which in no depth was significant (P>0.05). Partial dentinal tubule occlusion was observed with FESEM in each of the experimental groups as compared to the control group. Conclusion: The microhardness values were higher in all groups than in the control group. The laser might be more successful in remineralization than the other ones.

scholarly journals Effect of Delayed Light-Curing Through a Zirconia Disc on Microhardness and Fracture Toughness of Two Types of Dual-Cure Cement

2019 ◽  
Author(s):  
Pouran Samimi ◽  
Sara Kaveh ◽  
Maryam Khoroushi
Keyword(s):  
Fracture Toughness ◽  
Delay Group ◽  
Fracture Toughness Test ◽  
Irradiation Group ◽  
Significant Difference ◽  
Group A ◽  
Light Curing ◽  
Group B ◽  
Post Hoc ◽  
Group D

Objectives: Photopolymerization immediately sets dual-cure cements and prevents the continuation of chemical polymerization. Delayed light-curing allows the chemical process to continue up to the point before starting irradiation; however, there is a controversy in this respect. The present study evaluates the effect of delayed light-curing through a zirconia disc on the microhardness and fracture toughness (KIC) of two types of dual-cure cement. Materials and Methods: Samples measuring 25×5×3 mm3 were prepared for fracture toughness test, and discs measuring 5 mm in diameter and 3 mm in thickness were prepared for microhardness test using Bifix and BisCem cements. Light-curing protocols were as follows: immediate light-curing (group A), a 2-minute delay (group B), a 5-minute delay (group C), direct irradiation (group D), and no irradiation (group E). In groups A to C, light-curing was carried out through a zirconia disc. Data were analyzed by two-way and one-way analysis of variance (ANOVA), post-hoc Tukey's test, and Kruskal-Wallis test at 95% confidence interval. Results: There was a significant difference in the microhardness of the cements (P=0.00). Delayed light-curing had no effect on microhardness (P=0.080). The microhardness of BisCem in group E was significantly lower than that in group D (P=0.015). The fracture toughness of Bifix in groups B and C was significantly different than that in group E and BisCem groups. Conclusions: Under the limitations of our study, delayed light-curing had different effects on microhardness and fracture toughness. Differences in light-curing protocols resulted in different effects based on the cement type. Light-curing is recommended to achieve optimal mechanical properties.

scholarly journals Influence of curing mode of resin luting cements on bond strength to dentin

2017 ◽  
Vol 15 (4) ◽  
pp. 258
Author(s):  
Marcelo Giannini ◽  
Andreia Assis Carvalho ◽  
Ariovaldo Stefani ◽  
Wladimir Franco de Sá Barbosa ◽  
Lawrence Gonzaga Lopes
Keyword(s):  
Bond Strength ◽  
Testing Machine ◽  
Resin Cement ◽  
Control Group ◽  
Resin Cements ◽  
Luting Cements ◽  
Halogen Light ◽  
Significant Difference ◽  
Tooth Surfaces ◽  
Light Curing

Self-adhesive, dual-polymerizing resin cements require no treatment to the prepared tooth surfaces before cementation. Aim: The aim of this study was to evaluate the influence of curing mode on bond strength (BS) of three cementing systems to bovine dentin. Methods: The buccal enamel surfaces of 50 bovine incisors were removed to expose dentin and to flat the surface. The teeth were divided into five groups (n=10), which consisted of two resin cements (Multilink and Clearfil SA Cement) that were tested in dual- (halogen light for 40 s) and self-cured modes, and a control (RelyX ARC). Two cylinders of resin cements (1.0 mm X 0.75 mm) were prepared on each bonded dentin surface. After 24h at 37oC, resin cylinders were subjected to micro-shear testing in a universal testing machine (4411/Instron - 0.5 mm/min). Data were statistically analyzed by two-way ANOVA, Tukey and Dunnett`s test (5%). Results: Multilink showed higher BS than those observed on Clearfil SA. Light-curing resulted in higher BS for both Multilink and Clearfil SA. When Multilink was light-cured, no significant difference on BS was demonstrated between it and RelyX ARC. Conclusions: The highest BS values were obtained in control group and light-cured Multilink resin cement.

scholarly journals Shear Bond Strength Comparison between Two Orthodontic Adhesives and Self-Ligating and Conventional Brackets

2007 ◽  
Vol 77 (4) ◽  
pp. 701-706 ◽  
Author(s):  
Rodney G. Northrup ◽  
David W. Berzins ◽  
Thomas Gerard Bradley ◽  
William Schuckit
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Orthodontic Adhesives ◽  
Significant Difference ◽  
Conventional Brackets ◽  
Group 3 ◽  
Group 2 ◽  
Post Hoc ◽  
Group 1

Abstract Objective: To evaluate and compare the shear bond strengths of two adhesives using two types of brackets: a conventional and a self-ligating bracket system. Materials and Methods: Sixty extracted human premolars were collected. The premolars were randomly divided into three groups of 20 teeth. All three groups were direct bonded. Groups 1 and 2 used light-cured adhesive and primer (Transbond XT) with a conventional (Orthos) and a self-ligating bracket (Damon 2), respectively. Group 3 used a light-cured primer (Orthosolo) and a light-cured adhesive (Blūgloo) with a self-ligating bracket (Damon 2). The specimens were stored in distilled water at 37°C for 40 ± 2 hours, after which they were debonded and inspected for Adhesive Remnant Index (ARI) scoring. Results: The mean shear bond strength was 15.2 MPa for group 1, 23.2 MPa for group 2, and 24.8 MPa for group 3. A one-way analysis of variance and post hoc Tukey test showed significant differences in bond strength (P &lt; .001) between group 1 and groups 2 and 3 but no significant difference (P &gt; .05) between groups 2 and 3. A Weibull analysis demonstrated that all three groups provided sufficient bond strength with over 90% survival rate at normal masticatory and orthodontic force levels. A Kruskal-Wallis test showed no significant difference (P &gt; .05) in ARI scores among all three groups. Conclusions: All three groups demonstrated clinically acceptable bond strength. The Damon 2 self-ligating bracket exhibited satisfactory in vitro bond strength with both adhesive systems used.

Selection for crude protein content in Phalaris tuberosa L. I. Response to selection and preliminary studies on correlated responses

1969 ◽  
Vol 20 (4) ◽  
pp. 643 ◽  
Author(s):  
RJ Clements
Keyword(s):  
Crude Protein ◽  
Nutritive Value ◽  
Breeding Population ◽  
In Vitro Digestibility ◽  
Seedling Vigour ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Selection For ◽  
Pasture Plant

In a highly variable breeding population of P. tuberosa, marked responses were obtained to three generations of selection for high and low crude protein concentration (percentage nitrogen x 6.25) in whole tillers at heading. Total response was similar in each direction, and realized heritability estimates were h2 = 0.25 and h2 = 0.20 in the high and low directions respectively. The responses were accompanied by positively correlated changes in in vitro digestibility and in characters commonly used as indicators of nutritive value of herbage. However, there were large negatively correlated changes in seedling vigour, relative growth rates, and other morphological and physiological characters. The implications of the results for pasture plant breeding are discussed.

scholarly journals Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories

2013 ◽  
Vol 18 (6) ◽  
pp. 112-116
Author(s):  
Sergio Luiz Mota Júnior ◽  
Márcio José da Silva Campos ◽  
Marco Abdo Gravina ◽  
Marcelo Reis Fraga ◽  
Robert Willer Farinazzo Vitral
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Light Exposure ◽  
Orthodontic Brackets ◽  
Light Refraction ◽  
New Device ◽  
Halogen Light ◽  
Significant Difference ◽  
Light Curing

OBJECTIVE: development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. METHODS: One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI) was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. RESULTS: The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05) and the ARI (p > 0.05) between the subgroups. CONCLUSION: The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

scholarly journals Effects of delivering the same radiant exposures at 730, 1450, and 2920 mW/cm2 to two resin-based composites

2017 ◽  
Vol 11 (01) ◽  
pp. 022-028 ◽  
Author(s):  
Maan M. AlShaafi
Keyword(s):  
Fourier Transform ◽  
Degree Of Conversion ◽  
Attenuated Total Reflectance ◽  
Curing Time ◽  
Total Reflectance ◽  
Metal Rings ◽  
Significant Difference ◽  
Light Curing ◽  
Knoop Microhardness ◽  
Different Depths

ABSTRACT Objective: To evaluate the effects of curing two resin-based composites (RBC) with the same radiant exposures at 730, 1450, and 2920 mW/cm2. Materials and Methods: Two types of RBC, Filtek Supreme Ultra and Tetric-EvoCeram-Bulk Fill, were light-cured to deliver the same radiant exposures for 5, 10, or 20 s by means of a modified Valo light emitted diode light-curing unit with the light tip placed directly over each specimen. The RBC was expressed into metal rings that were 2.0 and 4.0 mm in thickness, directly on an attenuated total reflectance Fourier transform infrared plate heated to 33°C, and the degree of conversion (DC) of the RBC was recorded. The specimens were then removed and the Knoop microhardness (KHN) was tested at both the bottom and the top of each specimen. The KHN was tested again after 24 h and 7 days of storage in the dark at 37°C and 100% humidity. The DC and KHN results were analyzed with Fisher's protected least significant difference at α = 0.05. Results: The DC values for the specimens cured at the three different irradiance levels were similar. However, at different depths, there were differences in the DC values. In general, there were no clear differences among the samples cured in the three different groups, and the KHN was always greater 24 h and 7 days later (P < 0.05). Conclusions: Despite the curing time, and as long as the samples were cured with the same radiant exposures, there were no significant effects on the DC and KHN of both RBCs.

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