[Show abstract][Hide abstract] ABSTRACT: Aim: The aim of this in vitro study was to investigate the synergistic effect of chemical degradation (erosion) and three-body abrasion (mechanical degradation) on the surface roughness (Ra) and hardness (KHN) of two nanorestorative materials and two conventional materials. Methods: Discshaped specimens (5 mm in diameter, 2 mm thick) of Filtek Z350™ and TPH Spectrum™ composites and Ketac Nano™ and Vitremer™ light-curing glass ionomer cements, nanomaterials and conventional materials were prepared according to the manufacturer's instructions. After 24 h, polishing procedures were performed and initial measurements of Ra and KHN were taken in all specimens. The specimens were divided into 12 groups (n = 10) according to material and storage media: artificial saliva, orange juice, and Coca-Cola®. After 30 days of storage, the specimens were submitted to mechanical degradation and re-evaluated for Ra and KHN. Data were tested for significant differences by repeated-measure three-way ANOVA and Tukey's tests (p<0.05). Results: Erosion and abrasion wear significantly decreased hardness of all materials. Only Filtek Z350 roughness, however, was not affected by erosion and abrasion. All materials showed a significant increase in surface roughness after erosion and abrasion, except for Filtek Z350. After chemical and mechanical degradation, the KHN of all samples had decreased significantly. After mechanical degradation, the acidic drinks (Coca-Cola® and orange juice) were more aggressive than artificial saliva to all materials. Conclusions: A synergistic effect was observed by the increase in roughness for all materials, except for Filtek Z350; hardness values decrease for all materials, regardless of whether they were nanofilled or not. The RMGICs were more susceptible to degradation than the composites, considering both hardness and roughness surface parameters.
Full-text · Article · Jun 2015 · Brazilian Journal of Oral Sciences
[Show abstract][Hide abstract] ABSTRACT: This study evaluated the effects of chemical agents on the physical properties and structure of primary pulp chamber dentin using surface roughness, microhardness tests, and scanning electron microscopy (SEM). Twenty-five primary teeth were sectioned exposing the pulp chamber and were divided into five groups (n = 5): NT, no treatment; SH1, 1% sodium hypochlorite (NaOCl); SH1U, 1% NaOCl + Endo-PTC®; SH1E, 1% NaOCl + 17% EDTA; and E, 17% EDTA. After dentin treatment, the specimens were submitted to roughness, microhardness testing, and SEM analysis. Roughness and microhardness data were submitted to one-way ANOVA and Tukey's test (P < 0.05). The SH1E group showed the highest roughness, followed by the E group (P < 0.05) when compared with the NT, SH1, and SH1U groups. Microhardness values of SH1 and SH1U showed no significant difference as compared to the NT (control) group (P > 0.05). Microhardness values could not be obtained in the EDTA groups (SH1E and E). The presence of intertubular dentin with opened dentin tubules was observed in the NT, SH1, and SH1U groups. SH1E showed eroded and disorganized dentin with few opened tubules and the intertubular/peritubular dentin was partially removed. Considering the physical and structural approaches and the chemical agents studied, it can be concluded that NaOCl and NaOCl associated with Endo-PTC® were the agents that promoted the smallest changes in surface roughness, microhardness, and structure of the pulp chamber dentin of primary teeth.
Full-text · Article · Apr 2014 · Microscopy Research and Technique
[Show abstract][Hide abstract] ABSTRACT: Objective: To evaluate antibacterial effect of a triclosan methacrylate monomer added to an experimental resin composite on S mutans biofilm growing
Method: Triclosan metacrylate monomer was synthesized by esterification chemical process. Experimental resin composites were prepared using: C1: 50% BISEMA, 35% TEGDMA and 65% BaAlSi fille and C2: C1+30% triclosan monomer. Photo initiator system was comprised by 2% BAPO and 0.1% BHT for both composites. Ten specimens were obtained from each material. The antibacterial activity of triclosan metacrylate was assayed against mature Streptococcus mutans biofilms. Streptococcus mutans strains were grown for 24 h, adjusted to an optical density (OD550nm) of 1.0, and diluted 20-fold in brain heart infusion broth supplemented with 0.1% sucrose. Biofilms were statically formed during 24 h on specimens. Specimens were washed for 5 min and biofilms disrupted by vortexing. Cell suspensions were serially diluted and plated onto mitis salivarius agar. After incubation for 48 h, cell counting was performed. Experiment was conducted in triplicate. Data were submitted to one way ANOVA (p<0.01).
Result: Bacterial counting (Log) in the control group was significantly higher than (Log 8.9 ±0.29) C2. Triclosan methacrylate provided a 19.1% reduction on bacterial growing. That difference was statistically significant (p<0.01), showing an antibacterial effect against Streptococcus mutans of 19.1% reduction.
Conclusion: Triclosan metacrylate monomer demonstrated inhibition effect against Streptococcus mutans when added to experimental resin composite.
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to evaluate the nanoleakage patterns in indirect composite restorations bonding to dentin using different combinations of Resin Coating, after thermal and load cycling. Twenty five extracted third molars were used in the study; two box-like Class II cavities were prepared in each tooth (mesial and distal surface). The 50 cavities were distributed in 5 groups according to the RC materials combinations: G1: Etch-rinse 2 steps/Hydrophobic monomer; G2: Etch-rinse 2steps/Flow composite-resin, G3: Self-etch 1step, G4: Self-etch1step/Flowable composite resin liner, G5: Self-etch 2step/Flowable composite-resin liner. The cavities were molded with a vinyl polysiloxane impression material and the molds were poured with stone plaster. The fillings were confectioned using the Sinfony composite system (3 M/ESPE) and cemented with resin luting cement (Rely X ARC). After 24 hours, the teeth were submitted to thermocycling (2000 cycles, 5° to 55°C) and load cycling (250,000 cycles, 30 N). Past 24hours, the restored teeth were sectioned into serial slabs and immersed in 50% ammoniacal silver nitrate for 24 h, exposed to photo-developing solution for 8 h, carbon coated and observed in SEM using backscattered electron mode. Diverse nanoleakage patterns were observed for the different RC combinations. Silver accumulation were observed in the entire thickness of the hybrid layer in G1 and G2 groups, while in the “all in one” self-etch groups (G3 and G4) silver accumulations similar to “water trees” within the adhesive layer were observed. In G5 group, less nanoleakage than other groups was observed and it was limited to the hybrid layer. The group G5 presented a superior behavior and revealed less nanoleakage compared to the other groups.
[Show abstract][Hide abstract] ABSTRACT: Objective: The aim of this study was to evaluate bacterial inhibition promoted by a novel triclosan methacrylate monomer added to an monomeric experimental material.
Method: Triclosan methacrylate monomer was synthesized by esterification chemical process. Experimental materials were prepared using (1) TEGDMA - control group, and (2) TEGDMA+30% triclosan methacrylate monomer (TEG-TM). Both groups contained the following photoiniciator system: 2% BAPO and 0.1% BHT . Ten specimens were obtained from each material after photocuring for 40s using the Bluephase curing unit. The antibacterial activity of triclosan methacrylate was evaluated against mature Streptococcus mutans biofilms. Cultures of Streptococcus mutanswere grown for 24 h, adjusted to an optical density (OD550nm) of 1.0, and diluted 20-fold in brain heart infusion broth supplemented with 0.1% sucrose. Biofilms were statically formed during 24 h over the specimen surface. Specimens were washed for 5 min and biofilms disrupted by vortexing. Cell suspensions were serially diluted and plated onto mitis salivarius agar. After incubation for 48 h, cell counting was performed. Four independent experiments were conducted in triplicate. Data were analyzed with ANOVA (p<0.01).
Result: Bacterial counting (log) in the control group (8.7±0.27) was significantly higher than TEG-TM (6.9±0.37). That difference was statistically significant (p<0.01), showing an antibacterial effect against Streptococcus mutansof 1.8 log order reduction.
Conclusion: The triclosan metacrylate monomer demonstrated inhibition effect against Streptococcus mutans when added to TEGDMA and can be added to resinous materials to control the bacterial colonization on material surface.
[Show abstract][Hide abstract] ABSTRACT: To evaluate in the laboratory the roughness (Ra) and micromorphology surface of the nanofilled resin-modified glass-ionomer (Ketac N100) subjected to biomechanical degradation, compared to Vitremer, Ketac Molar Easymix and Fuji IX.
Specimens obtained from the ionomers were divided into two storage groups (n = 10): relative humidity and S. mutans biofilm (biodegradation). After 7 days, Ra values and micrographs were obtained. Then, the brushing abrasion test (mechanical degradation) was conducted with dentifrice slurry (three-body) and the specimens were reassessed. Data were submitted to repeated measures three-way ANOVA and Tukey tests (P < 0.05).
There was significant interaction among the factors: material, storage and abrasion (before/after). Vitremer showed similar Ra values between storage groups, while the other materials presented higher Ra values after biodegradation test. Concerning biomechanical challenge, Ketac N100 presented the lowest Ra values. Ketac Molar Easymix and Fuji IX presented undesirable roughening of their surfaces under the detrimental conditions tested. The eroded aspect after biodegradation with filler exposure after mechanical degradation was evident.
Full-text · Article · Dec 2012 · American journal of dentistry
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES: To evaluate: 1) the in vitro antibacterial, cytotoxic and mechanical properties of a resin-modified glass ionomer cement (RMGIC) containing different concentrations of chlorhexidine (CHX) and 2) the in vivo microbiologic action of the best concentration of CHX associated with the RMGIC applied on remaining dentin after indirect pulp treatment (IPT). METHODS: For the in vitro studies, RMGIC was associated with 0.2, 0.5, 1.25 and 2.5% CHX. Microbiologic evaluation consisted of an agar diffusion test on cariogenic bacteria for 24h. Odontoblast-like cell metabolism and morphology analyses measured the cytotoxic effects of the RMGIC groups after 24h. The same groups were submitted to compressive and diametral tensile strength. The in vivo treatment consisted of IPT using an RMGIC associated with the best CHX concentration. Clinical and microbiologic evaluations were performed before and after 3 months. RESULTS: The use of 1.25% CHX significantly improved the antibacterial effects of the evaluated RMGIC, without causing any detrimental effects to the odontoblast-like cells and on the mechanical properties. This RMGIC and CHX combination completely eliminated mutans streptococci after 3 months of IPT. CONCLUSION: The RMGIC and 1.25% CHX mixture showed great biological and mechanical behavior and could be a good treatment against caries progression. CLINICAL SIGNIFICANCE: The association of CHX with a liner RMGIC opens a new perspective for arresting residual caries after IPT.
Full-text · Article · Oct 2012 · Journal of dentistry
[Show abstract][Hide abstract] ABSTRACT: This study evaluated the influence of material combinations used in the resin coating technique (RCT) on the marginal adaptation of indirect restorations with gingival margins in enamel (EM) and cement (CM). Eighty third-molars were used. Two cavities were prepared in each tooth. The cavities were distributed into 16 groups. Cavities with EM were filled with the following material combinations: G1: Single-Bond 2 (Sb2), G2: Sb2 + Bond/Scotchbond-Multipurpose (Sb2B), G3: Sb2 + Filtek-Flow Z350 (Sb2Fl), G4: Scotchbond-Multipurpose (SBMP), G5: Clearfil-S3 (CS3), G6: CS3 + Bond/Clearfil-SE Bond (CSE3B), G7: CS3 + Protect Liner F (CS3PL) and G8: Clearfil SE Bond + Protect Liner F (CSEBPL). The same combinations were applied to the cavities in CM: G9, G10, G11, G12, G13, G14, G15, G16, respectively. The fillings were performed with the Sinfony-System (3M/ESPE). After 24 h, the teeth were submitted to thermocycling (2,000 cycles, 5° to 55°C) and load-cycling (50,000 cycles, 50 N). Next, the Caries-Detector (Kuraray) was applied to the restoration margins. Images from the proximal margin were evaluated using the Image-Tool 3.0 software. The results were submitted to ANOVA and Tukey's test (α=0.05). The mean values (%) for the groups were: EM: G1=46.68, G2=15.53, G3=19.83, G4=27.53; G5=59.49, G6=25.13, G7=34.37, G8=15.20; CM: G9=38.38, G10=23.25, G11=26.97, G12=25.85, G13=37.81, G14=30.62, G15=29.17, G16=20.31. The highest percentages of marginal gap on EM or CM were found in the groups that did not use a liner. It can be concluded that the most appropriate RCT combinations were the groups that used a liner.
Full-text · Article · Jan 2012 · Brazilian dental journal
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to assess Knoop hardness at different depths of a dual-cured self-adhesive resin cement through different thicknesses of Empress Esthetic® ceramic.Flattened bovine dentin was embedded in resin. The cement was inserted into a rubber mold (0.8 x 5 mm) that was placed between two polyvinyl chloride plastic films and placed over the flat dentin and light cured by Elipar Trilight-QTH (800 mW/cm2) or Ultra-Lumelight-emitting diode (LED 5; 1585 mW/cm2) over ceramic disks 1.4 or 2 mm thick. The specimens(n=6) were stored for 24 hours before Knoop hardness (KHN) was measured. The data were submitted to analysis of variance in a factorial split-plot design and Tukey's test (a=0.05).There was significant interaction among the study factors. In the groups cured by the QTHunit, an increase in ceramic thickness resulted in reduced cement hardness values at all depths, with the highest values always being found in the center (1.4 mm, 58.1; 2 mm, 50.1)and the lowest values at the bottom (1.4 mm,23.8; 2 mm, 20.2). When using the LED unit, the hardness values diminished with increased ceramic thickness only on the top (1.4 mm,51.5; 2 mm, 42.3). In the group with the 1.4-mm-thick disk, the LED curing unit resulted in similar values on the top (51.5) and center(51.9) and lower values on the bottom (24.2).However, when the cement was light cured through the 2-mm disk, the highest hardness value was obtained in the center (51.8), followed by the top (42.3) and bottom (19.9),results similar to those obtained with the QTH curing unit (center > top > bottom). The hardness values of the studied cement at different depths were dependent on the ceramic thickness but not on the light curing units used.
No preview · Article · Dec 2011 · Operative Dentistry
[Show abstract][Hide abstract] ABSTRACT: To characterize the mechanical and biological properties of a resin-modified glass ionomer cement (RMGIC) containing doxycycline hyclate.
The antibacterial effect of RMGIC containing 1.5, 3.0 and 4.5% doxycycline hyclate was assessed using two experiments - agar diffusion test for 24h and biofilm assay for 24h and 7 days - against some cariogenic bacteria. Briefly, base layers of BHI agar and 300μL of each inoculum were prepared in Petri dishes with 6 wells that were completely filled with materials. After 24h incubation, zones of bacterial growth inhibition were measured using a digital caliper. Biofilm assays were conducted using RMGIC specimens immersed in 24-well plates containing the inoculum in BHI broth. After 24h and 7 days, each specimen were removed, vortexed and the suspension diluted and inoculated in BHI plates for subsequent bacterial counting. Cytotoxicity tests used 50 specimens made in sterilized metal molds, including Vitrebond as positive control. Extracts from every specimen were applied on the MDPC-23 odontoblast-like cells for 24h. The MTT assay and SEM evaluation determined cell metabolism and morphology, respectively. 80 cylindrical specimens were made from the previously cited groups, and were submitted to testing with a universal testing machine (Instron 4411) using a crosshead speed of 1.0mm/min for compressive strength and 0.5mm/min for diametral tensile strength, respectively. Data from antibacterial and cytotoxic effects, and mechanical properties were submitted to appropriated statistical tests.
All tested groups showed growth inhibition of all tested strains (p<0.05) in 24h for both microbiological tests, but only 4.5% doxycycline have antibacterial effect after 7 days. None of doxycycline concentrations caused toxic effect to the MDPC-23 cells or presenting alterations to mechanical properties.
The incorporation of up to 4.5% doxycycline hyclate into RMGIC inhibits important oral microorganisms, without modifying biological and mechanical characteristics of the dental material, suggesting a new alternative for the treatment of dental caries.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass ionomer, Ketac N100 and a composite, Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by scanning electron microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way analysis of variance (ANOVA) and Tukey tests (p<0.05). There was statistically significant interaction among factors: material, storage (humidity/biofilm), and abrasion (before/after). After biodegradation (S mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100, and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. This study demonstrated that the nanotechnology incorporated in restorative materials, as in composite resin and resin-modified glass ionomer, was important for the superior resistance to biomechanical degradation.
[Show abstract][Hide abstract] ABSTRACT: Objectives: The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass-ionomer - Ketac N100) and a composite - Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Methods: Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days storage, roughness values (Ra) and micrographs by Scanning Electron Microscopy (SEM) was obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way ANOVA and Tukey's tests (p<0.05). Results: There was statistically significant interaction among factors: material, storage (humidity/biofilm) and abrasion (before/after). After biodegradation (S. mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100 and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. Conclusions: The nanotechnology incorporated in the materials studied was important for the superior resistance to biomechanical degradation observed.
[Show abstract][Hide abstract] ABSTRACT: Objectives: The aims of this study were to evaluate the antibacterial activity and mechanical properties of a liner resin-modified glass-ionomer cement (RMGIC) containing chlorhexidine digluconate. Methods: 0.2%; 0.5% and 1.25% chlorhexidine digluconate were added to RMGIC Fuji Lining LC. The antibacterial activity was assessed by the agar diffusion test. Inoculums of Streptococcus mutans, Lactobacillus acidophilus, Lactobacillus casei and Actinomyces viscosus were cultivated in BHI broth and incubated at 37 C for 24 h. Base layers of BHI agar and 300L of each inoculums were prepared in Petri dishes. Six wells per plate were made at equidistant points and immediately filled with the test or control (RMGIC) materials. After incubation of the plates for 24 h, zones of bacterial growth inhibition were measured using a digital caliper. Data were submitted to Wilcoxon and Mann-Whitney tests. For mechanical tests, ten round-shaped specimens (2 mm x 4 mm) of experimental and control groups were prepared using silicone molds. Specimens were light-cured for 30 seconds, stored in plastic containers and stored at 37 C and relative humidity for 24 hours. Then, the specimens were submitted to compressive strength at a 0.5 mm/min, and diametral tensile strength at a crosshead speed of 1.0 mm/min in an universal testing machine (Instron 4411). Data were submitted to ANOVA and Tukey tests (p<0.05). Results: Concerning the antibacterial effect, all experimental groups showed growth inhibitions of all strains compared to the control group (p<0.05). For compressive strength test, RMGIC containing 2.5% chlorhexidine digluconate (23.09MPa) was statistically different from control (30.61MPa) (p<0.05). No significant difference was found for diametral tensile strength test. Conclusion: The addition of chlorhexidine digluconate up to 1.25% to liner glass ionomer enhanced the antibacterial effect without alteration of mechanical properties of cement.